text:
Wearable and portable self-powered units have stimulated considerable attention in both the scientific and technological realms. However, their innovative development is still limited by inefficient bulky connections between functional modules, incompatible energy storage systems with poor cycling stability, and real safety concerns. Herein, we demonstrate a flexible solar-charging integrated unit based on the design of printed magnesium ion aqueous asymmetric supercapacitors. This power unit exhibits excellent mechanical robustness, high photo-charging cycling stability (98.7% capacitance retention after 100 cycles), excellent overall energy conversion and storage efficiency (ηoverall = 17.57%), and outstanding input current tolerance. In addition, the Mg ion quasi-solid-state asymmetric supercapacitors show high energy density up to 13.1 mWh cm−3 via pseudocapacitive ion storage as investigated by an operando X-ray diffraction technique. The findings pave a practical route toward the design of future self-powered systems affording favorable safety, long life, and high energy.
The growing demand for miniaturization and multi-functionalization of portable electronics has spurred the development of integrated energy systems that can hybridize energy harvesting and storage in a flexible and even wearable fashion1. In terms of energy-harvesting modules, photovoltaic (PV) devices, especially silicon solar cells, have become ubiquitous for harnessing clean and accessible solar energy. However, due to the intermittent and unpredictable nature of sunlight, the fluctuating output energy of PV panels is highly unlikely to support the direct powering of wearable electronics; thus, energy needs to be stored in a reliable module for further use on demand. Among a plethora of emerging energy storage technologies, supercapacitors offer high power density and excellent tolerance to the variation of input current, thereby being perfect for accommodating PV modules for building efficient self-powered platforms2. Despite these meritorious properties, supercapacitors suffer from relatively low energy density when compared with metal-ion battery systems, which significantly impedes their applications in the realm of wearable technology. In this regard, developing asymmetric supercapacitors (ASCs) remains a feasible solution: their extended operating voltage favors enhanced energy density without sacrificing high power capability and good current tolerance; hence, benefiting the overall performance of PV-supercapacitor integrated systems3. Recently, Zhang et al.4 demonstrated a flexible photo-capacitor based on a Co9S8-MnO2//TiO2 asymmetric electrode design. In our previous work, a wearable photo-rechargeable lithium-ion hybrid capacitor (LIC) also demonstrated a high overall efficiency up to 8.41%5.
Safety is the primary concern for wearable energy systems, which therefore demand aqueous electrolytes along with non-flammable electrodes. Although it is difficult for an aqueous electrolyte system to achieve a high working voltage compared to organic electrolytes (2.5–4.0 V), the two order of magnitude greater ionic conductivity endows it with fast ion transport and hence, high-rate performance. Furthermore, it is interesting to note that neutral aqueous electrolyte-based ASCs can achieve a wide working voltage from ~1.6 to 2.0 V, which exceeds the theoretical limit of the water splitting potential, 1.23 V. Such a large operating voltage is achieved by high hydrogen and oxygen evolution overpotentials in a neutral aqueous system. Of particular note, these neutral electrolytes readily overcome the hazardous concerns of flammability and corrosion that occur with organic and acidic/alkaline electrolytes; thus, overcoming the substantial safety issues encountered with wearable devices. As such, exploiting neutral electrolytes with multivalent metal-ions (Mg2+, Al3+, Zn2+, Ca2+, etc.) for aqueous ASCs represents a promising strategy to synchronously address the safety challenges while boosting energy density6,7. However, until now, the development of a wearable solar-charging power unit employing multivalent metal-ion ASCs based on directly printing designs is still in its nascent stage, and hence in need of systematic exploration.
Herein, we devise aqueous Mg ion ASCs targeting the construction of wearable solar-charging integrated power units. Such flexible, quasi-solid-state ASCs (MnO2//VN) are assembled with nanoflower-like MnO2 as the positive electrode, nanowire-shaped VN as the negative electrode, and MgSO4-PAM gel as the electrolyte, synergistically achieving a wide potential window (up to 2.2 V), favorable volumetric energy density (up to 13.1 mWh cm−3), high power density (up to 440 mW cm−3), and outstanding cycling stability (capacitance retention up to 95% after 5000 cycles). The Mg ion electrochemical system developed in this work has the following attributes: (i) a superior charge storage efficiency due to the dual-electron transfer possible with Mg2+-ion intercalation in comparison with typical alkali metal-ion (Li+, Na+, K+) systems; (ii) a facile redox process enabled by the highly efficient surface ion migration and near-surface ion intercalation of nano-sized MnO2 and VN; and (iii) a wider voltage window owing to the negative hydrogen evolution reaction overpotential on VN surfaces. The Mg ion transport mechanism at the VN anode is further probed using operando X-ray diffraction (XRD) and ex situ X-ray photoelectron spectroscopy (XPS) techniques. Moreover, direct printing of such device arrays on the rear of flexible solar cells enables the fabrication of solar-charging power units with simplified configurations and mechanical robustness. Importantly, the printable and flexible integrated system thus-derived shows remarkable mechanical robustness, excellent photo-charging cycling stability (98.7% capacitance retention after 100 cycles), and efficient powering of electronic devices (e.g. a smart watch and a light-emitting diode), demonstrating great potential as self-powered wearable energy sources for safe use in practical scenarios.
Illustrating the configuration of solar-charging units
Figure 1a (i) illustrates the configuration of a flexible solar-charging self-powered unit, encompassing an energy-harvesting module (i.e. a flexible solar cell), an energy storage module (i.e. a printed quasi-solid-state ASC array on a polyimide substrate), and a plastic film capping layer. Note in Fig. 1a (ii) that the quasi-solid-state ASC is assembled by using vanadium nitride (VN) as the negative electrode, manganese oxide (MnO2) as the positive electrode, and MgSO4-polyacrylamide (PAM) gel as the electrolyte. Such an aqueous supercapacitor device is operated based on the pseudo-capacitive intercalation/de-intercalation of Mg2+ ions between VN and MnO2 electrodes. For the integrated unit, upon exposure to sunlight, the solar cell component enables the conversion of photo-irradiation into electricity and charges the supercapacitor simultaneously (photo-charging). The photo-charged supercapacitor can provide stored power for electronic devices anytime on demand (discharging). In addition, the entire integrated system complies with a thin-film planar design, which endows it with good flexibility. As a proof-of-concept demonstration, a solar-charging self-powered unit can be directly worn and function as a reliable power source for powering a portable electronic watch, as shown in Fig. 1a (iii).
Characterizing as-prepared VN nanowires
The synthetic route to VN nanowires was adopted from a reported recipe (Supplementary Fig. 1a)8. Scanning electron microscopy (SEM; Fig. 1b) images show the typically porous nanowire structure of VN, with uniform 120–150 nm in width and ~2 μm in length. Transmission electron microscopy (TEM; Fig. 1c) presents the detailed morphology of the porous VN nanowires, showing many interconnected open pores. Elemental mapping of the as-prepared VN reveals a homogeneous distribution of nitrogen and vanadium (Supplementary Fig. 1b). The appearance of an oxygen signal suggests the existence of surface-bound oxygen upon exposure to air. Further XPS analysis indicates the dominance of the V3+-binding state as well as the V−N signal (Supplementary Fig. 1c, d), implying the successful fabrication of VN. Note that there are no XPS peaks indicative of V4+ and V5+ states, which can be attributed to the excessive reduction from the long-term and high-temperature NH3 annealing process (600 °C for 3 h). Aberration-corrected scanning transmission electron microscopy (STEM) observations display the lattice fringes of VN (Fig. 1c inset; Supplementary Fig. 1e–g), with a lattice spacing of 0.21 nm matching well with the VN (200) plane. Figure 1d depicts the X-ray diffraction (XRD) pattern of synthesized VN samples. Characteristic peaks are found at 37.9° (111), 44.0° (200), and 64.1° (220), verifying the well-defined crystal structure of VN (JCPDS No. 25-1252). It is anticipated that such nanowire-shaped VN is key to achieving favorable electrochemical performances when used as electrodes due to: (1) the large aspect ratio, intrinsic porous structure, and nanometer sized dimensions (<20 nm) of the VN nanowires which endow them with high-rate capabilities and near-surface Mg2+ intercalation pseudo-capacitive behavior, a crucial factor for their superior rate capability and cycling stability. (2) the nanowire-shaped microstructure could become interwoven with each other thereby avoiding aggregation upon cycling, which has often been seen when using nanoparticle or nanosheet morphologies.
Investigating electrochemical properties of VN nanowires
The electrochemical performance of VN was systematically examined via a three-electrode cell system. Cyclic voltammetry (CV) measurements at a scan rate of 10 mV s−1 were carried out in various neutral aqueous electrolytes affording identical cation concentrations (Fig. 2a), including 0.5 M Li2SO4, 0.5 M Na2SO4, 0.5 M K2SO4, and 1.0 M MgSO4. It is interesting to note that the VN electrode exhibits the largest CV area in the Mg ion electrolyte. Figure 2b summarizes the gravimetric-specific capacitances calculated based on the CV profiles. The VN electrode manifests a specific capacitance of 230 F g−1 in the MgSO4 electrolyte, far superior to those achieved in Li2SO4 (120 F g−1), Na2SO4 (100 F g−1), and K2SO4 (70 F g−1). Such markedly enhanced capacitance in the Mg2+ electrolyte mainly stems from the following factors: (i) the bivalent metal-ion (Mg2+) possesses a higher theoretical capacitance due to dual-electron transfer during redox reactions. The possible Faradaic reactions of VN in an aqueous Mg2+ electrolyte can be described as follows9:
In this respect, the capacitance stored in the Mg2+ system should be twice that of other monovalent cation systems, which is in good agreement with the capacitance derived from the CV measurements. (ii) The relatively smaller ionic radius of Mg2+ ions (Mg2+: 0.72 Å, Li+: 0.76 Å, Na+: 1.02 Å, K+: 1.51 Å)10 leads to pseudo-capacitive-dominated charge storage behavior of the VN electrode.
Electrochemical impedance spectroscopy (EIS) studies offer further insights into the ionic and electronic transport properties of the VN electrode in different cation electrolytes (Supplementary Fig. 2a, b). At the low-frequency region, the steep shape of the straight lines reveals a typical capacitive behavior in various electrolytes. At the high-frequency region, the internal resistance (Rs) shows obvious differences (K+: 4 Ω, Na+: 5.5 Ω, Li+: 7 Ω, Mg2+: 8.5 Ω). Rs normally consists of the conductive resistance of the electrolyte, as well as the intrinsic contact resistance between electrode material and current collector. Since all the Nyquist plots were acquired based on the same electrode material and electrochemical cell configuration, the difference of Rs should be mainly attributed to the diverse conductive resistances of different cation electrolytes. Because of its bivalent nature and small ionic radius, Mg2+ ions exhibit relatively strong ionic bonds. Therefore, the diffusion of Mg2+ ions is more sluggish than that of monovalent cations. The higher resistance polarization of Mg2+ should result in a larger voltage hysteresis, which is helpful in extending the stable working voltage of VN in the Mg2+ electrolyte system. A Randles equivalent circuit with relative parameters is provided (Supplementary Fig. 2c; Supplementary Table 1), accompanied by the detailed discussions shown in Supplementary Note 1. Figure 2c displays the linear sweep voltammetry (LSV) polarization curves of a VN electrode in different cation electrolytes. It is evident that the Mg2+ system manifests the highest overpotential for hydrogen evolution. Along this line, the stable working voltage of the VN electrode in an Mg2+ electrolyte can be extended, corroborating the EIS analysis. Figure 2d summarizes the specific capacitances of VN in the Mg2+ electrolyte that correspond to the CV profiles at different scan rates (Fig. 2d, inset). The CV shapes are well maintained upon increasing the scan rate from 1 to 200 mV s−1, indicating the favorable rate performance of the VN electrode in the Mg2+ system. Note that the redox peak between −0.6 and −0.7 V only displays a slight shift when increasing the scan rates, indicating facile reaction kinetics during charge storage. As such, the charge stored by the Faradaic diffusion-controlled or non-Faradaic capacitive-tailored contributions can be analyzed by a b-value, which can be derived based on the equation i = aνb 11. In this sense, the b-value is respectively calculated at 0.91 and 0.90 for the anodic and cathodic peak (Supplementary Fig. 2d), implying that the contribution from capacitive behavior dominates. To further identify the contribution ratio, the current response can be expressed by combining the two separate mechanisms (surface capacitive behavior and diffusion-controlled Mg2+ insertion processes): i(V) = k1ν + k2ν1/2. Herein, k1ν and k2ν1/2 represent the capacitive- and diffusion-controlled current contributions, respectively. Figure 2e plots a capacitive current contribution at a CV scan of 10 mV s−1, exhibiting a large percentage of capacitance (72.6%). In addition, Fig. 2f presents the bar chart of calculated capacitive contributions at various scan rates. Obviously, the ratio of capacitive contribution increases (from 60% to 98%) as the scan rate is raised from 1 to 100 mV s−1, further verifying the capacitive-dominated reaction mechanism of the VN electrode.
Probing the electrochemical reaction mechanism of VN
To explore the reaction mechanism of the Mg2+ ions on the VN electrode, operando XRD analysis was performed by using VN as the target electrode and MnO2 as the counter electrode. All the XRD patterns were collected from the second cycle upon charge/discharge to avoid the irreversible reactions that occurred during the first cycle. Note that there are no new phases detected during the entire charge/discharge process. Figure 3a documents the obvious peak shift for the VN (200) plane (2θ: 44–45°). Upon charging (0–2.2 V), the diffraction peak gradually shifts toward high angles (2θ: 44.5–44.7°), indicating the contraction of the interplanar distance along the (200) direction. In response, the diffraction peak returns to the low angle position upon discharging, indicating an expansion of the lattice spacing. The interplanar distance is calculated according the Bragg equation (λ = 0.15406 nm), to reversibly increase by 0.2 Å (2.1 → 1.9 → 2.1 Å) during the charge/discharge process (as depicted in Fig. 3b). Such a periodic variation in the lattice spacing confirms the reversible pseudo-capacitive Mg ion intercalation/de-intercalation of the VN (200) plane without causing a phase transition11. At the same time, the contraction of the interplanar distance during the Mg ion pseudo-capacitive intercalation can be explained by an increase of the electrostatic attraction between the guest Mg ions and the host VN lattice12,13,14.
The pseudo-capacitive Mg ion intercalation mechanism of the VN electrode was verified by ex situ Mg 1s XPS measurements. As shown in Fig. 3c, the seven different sampling points are taken from a CV scan with a scan rate of 5 mV s−1. The Mg 1s peak is centered at 1303.3 eV, which can be assigned to Mg2+. As for the charging process (going from point 1 to 5), a gradual increase of the peak intensity can be clearly observed, reflecting the intercalation of Mg2+ ions. During the discharging process (from −0.9 to 0 V), a decline in signal intensity signifies Mg2+ de-intercalation. Furthermore, ex situ V 2p XPS spectra reveal the valence state change of vanadium upon charge/discharge (Supplementary Fig. 3). The peaks at 515.4 and 513.2 eV represent the contribution from V3+ and V2+, respectively15, without the presence of any new signals. In this regard, one can conclude that V3+ is the stable oxidation valence state in this VN electrode, whereas V2+ is the relatively stable reduction valence state. It is worth pointing out that charge compensation will occur when the amount of positive charge in active materials increases16; in other words, during the insertion of Mg2+ ions in the VN lattice. Figure 3d summarizes the proportion of vanadium valence states from the ex situ V 2p spectra. At the initial state, the concentration of V3+ and V2+ is 64% and 36%, respectively (point 1). In turn, the ratio of V3+ decreases to 58% at the fully charged state (point 5). Upon full discharge, the proportion of V3+/V2+ returns back to 63%/37% (point 7), which is in accordance with the initial state. Considering the surface-sensitive nature of the XPS technique, these results reveal that the highly reversible surface redox reactions between V3+/V2+ also contribute to the charge storage mechanism during the electrochemical process.
Evaluating performances of Mg ion quasi-solid-state ASCs
Quasi-solid-state ASCs were assembled in typical coin cell configurations, where the MnO2@carbon (MnO2@C) composite was employed as the positive electrode for the insertion/extraction of Mg2+ ions. The synthesized composites were subject to a wide suite of characterization tools (Supplementary Fig. 4). The three-dimensional MnO2 nanoarchitecture boosts the Mg ion diffusion, while the conductive carbon matrix improves the electrical conductivity of the hybrid electrode. The electrochemical performances of the MnO2@C composites were systematically measured in a three-electrode system (Supplementary Fig. 5). The electrode delivers a specific capacitance of 240 F g−1 at a scan rate of 10 mV s−1 with a broad potential window (from −0.3 to 1.2 V vs. Ag/AgCl), which is similar to other cation electrolyte systems (Li+, Na+, and K+). The MnO2 electrode is likely to manifest a solid-state diffusion dominated charge storage mechanism, which is different from the capacitive charge storage behavior of the VN electrode (Supplementary Fig. 6)17.
To assemble a quasi-solid-state ASC, the starch/PAM/MgSO4 gel was introduced as the electrolyte18. In comparison with the commonly used polyvinyl alcohol, such a PAM-based gel matrix exhibits excellent compatibility with Mg cations. As expected, starch molecules and acrylamide molecules physically entangle and interpenetrate with each other to form an ion conductive network with favorable water absorption ability and mechanical robustness, as demonstrated in Fig. 4a. The as-prepared gel electrolyte can return to its initial state after various deformations, such as flatting, bending and/or stretching. Figure 4b presents CV curves for both a VN negative electrode and an MnO2 positive electrode at a scan rate of 10 mV s−1, indicating that the constructed asymmetric device can achieve a voltage window of 2.1 V or even larger. CV scans at different voltage ranges from 1.4 to 2.6 V were then carried out. Note that there is no obvious polarization even when the applied voltage is extended to 2.2 V (Fig. 4c, red line). Such a broad voltage range outperforms most ASCs reported recently19,20. Figure 4d shows the galvanostatic charge/discharge (GCD) curves of our quasi-solid-state ASCs at different current densities from 2 to 12 mA cm−2. At 2 mA cm−2, the discharge time reaches 637 s, corresponding to an areal capacitance of 576 mF cm−2, which is 79.2% of the identical device tested in a liquid electrolyte (Fig. 4e; Supplementary Fig. 7). Interestingly, once the current densities exceed 4 mA cm−2, the areal capacitance of the gel electrolyte is even higher than that of the liquid electrolyte-based system. The superior rate performance presented in gel electrolyte to that in the liquid electrolyte deserves further investigation. As such, comparative EIS profiles between the gel electrolyte and the liquid electrolyte systems before and after electrochemical tests have been collected (Fig. 4f; Supplementary Fig. 8). All these Nyquist plots have been fit according to a Randles equivalent circuit (Supplementary Table 2). It is evident that the Rs of the gel electrolyte system only exhibits a negligible increase (0.037 Ω) after electrochemical measurements, which is smaller than the 0.243 Ω of the liquid electrolyte system. The much steeper line at the low-frequency range in the Nyquist plots for the gel system (especially after the electrochemical tests) also indicates enhanced ion diffusion. Such a better electrolyte ion diffusion capability is the key to achieving higher rate performance. Meanwhile, exhaustive morphological and elemental characterization provides evidence that the unique porous structure, high water content ratio and tight electrolyte/electrode interface contribute to the enhanced ion diffusion features of the gel electrolyte-based system (Supplementary Figs. 9–12). Notably, 95% capacitance retention can be achieved at a high current density of 16 mA cm−2 after 5000 cycles, demonstrating an outstanding cycling stability of the assembled quasi-solid-state ASC (Fig. 4g). Furthermore, there is no distortion of the charge/discharge curves even for the last several cycles, as shown in the inset to Fig. 4g.
Figure 4h presents a Ragone plot of the volumetric energy density and the power density of our quasi-solid-state ASC (VN//MnO2) in comparison with other recently reported quasi-solid-state supercapacitors tested in neutral gel electrolytes. Our device manifests a volumetric energy density of 13.1 mWh cm−3 at a power density of 72 mW cm−3. It also preserves 79% of its energy density when the power density is increased to 440 mW cm−3. These values are markedly superior to that of state-of-the-art systems9,19,20,21,22,23,24,25,26,27,28, including VOx//VN (LiCl/PVA)9, MnO2@NG//AC (LiCl/PVA)24, VN@MOF//AC (Na2SO4/PVA)19, and V2O3@C//Fe3O4@TiO2 (LiCl/PVA)26. The high energy density and excellent rate performance of our device can be mainly attributed to the significantly extended stable voltage range of the Mg ion system and the favorable pseudo-capacitive Mg ion charge storage behavior of the VN negative electrode.
Constructing flexible micro-asymmetric supercapacitors
In pursuit of portable, miniaturized and wearable energy storage devices, we next fabricated flexible micro-asymmetric supercapacitors (MASCs) consisting of VN and MnO2 interdigitated electrodes via screen printing29,30,31,32 (Supplementary Fig. 13). Figure 5a depicts the general procedure for the direct printing of MASCs, including the pre-patterning of Au films as the current collectors33, followed by deposition of interdigitated VN and MnO2 electrodes, and the application of the PAM-MgSO4 gel electrolyte (with detailed dimensions of the screen-printing pattern shown in Supplementary Fig. 14). The electrochemical performances of the as-constructed VN//MnO2 MASCs were characterized by CV and GCD measurements. Figure 5b shows the CV profiles of the MASC at different scan rates. Note that the open circuit voltage reaches a remarkable 2.2 V, exceeding most of the recently reported in-plane micro-supercapacitors and ASCs. A couple of redox peaks can still be detected, in good agreement with the foregoing results of the quasi-solid-state asymmetric SC in a coin cell configuration. The CV shape is well preserved from 10 to 200 mV s−1, suggesting excellent rate capability of the device. Figure 5c displays the GCD curves at different current densities from 0.5 to 12 mA cm−2, showing obvious triangular shapes. As such, our printed MASC delivers an areal capacitance of 28.5 mF cm−2 at 0.5 mA cm−2, while 42% of this capacitance remains upon testing at 12 mA cm−2, as shown in Fig. 5d. The thus-derived MASCs display a slow self-discharge process (Supplementary Fig. 15) and a stable long cycle performance (a capacitance retention of 90% after 8000 cycles; see Supplementary Fig. 16). In addition, the Ragone plot drawn in Supplementary Fig. 17 demonstrates that our printed MASCs harvest an energy density of 19.13 μWh cm−2 at a power density of 0.55 mW cm−2, outperforming those of recently reported in-plane micro-supercapacitors (see Supplementary Table 3 for detailed information).
To efficiently boost the operating voltage and capacitance output of a single device, MASCs could be easily connected in series or in parallel by optimizing the printing process. Figure 5e presents the GCD curves of single, series and parallel MASCs. In this regard, a series connection enables the extension of the output voltage to 4.4 V (double the 2.2 V for a single device). Meanwhile, the capacitance can be readily doubled by adopting a parallel connection, demonstrating advanced modulation for device integration33. To further evaluate the mechanical robustness of our MASC targeting practical wearable applications, we carried out GCD measurements under bending angles of 0°, 90°, 180°, and 360° (Fig. 5f, and inset). Notably, the shapes of the GCD curves with different bending angles only change slightly, with almost 100% of the initial capacitance retained on bending at 360°, thus demonstrating excellent mechanical flexibility. Such printed MASCs with their excellent mechanical properties are thus conducive to multi-field integration with solar cell systems.
Integrating flexible solar-charging self-powered units
The rapid development of wearable smart electronics has led to a huge demand for flexible, safe, and long-life energy sources34. The printed MASCs as demonstrated above could serve as viable energy storage devices, but might still not meet the self-powered requirements with no external charging supply, especially for wearable applications. In this respect, integration with an energy-harvesting component, such as a solar cell, is a feasible solution to both capture and energy storage within a single device. We started by evaluating our flexible VN//MnO2 ASC within a solar-charging integration system. To achieve this, a low-cost polycrystalline Si solar cell was employed as the PV module (Supplementary Fig. 18a, b) and an as-assembled quasi-solid-state ASC was used as the energy storage module. Figure 6a displays the solar-charging/discharging profiles of the integrated device under varied light intensities with the same discharge current density (1 mA cm−2). The output current density of the solar cell corresponding to the light intensity is shown in Supplementary Fig. 18c. When the light intensity was increased from 4 to 950 W cm−2, the output current density responsively increased from 1.6 to 114 mA cm−2. Such an abrupt increase in light intensity (current) could significantly shorten the duration of solar-charging (e.g. to 3 s). In addition, the discharge time is correspondingly reduced, which can be attributed to an increased IR drop at the large current densities. It is worth-noting that the discharge behavior can still return to the initial state upon dialing the light intensity back to 4 W cm−2, indicative of excellent rate capability. In other words, our ASC demonstrates the ability to withstand large currents (e.g., 114 mA cm−2), outperforming emerging energy storage counterparts (such as lithium ion batteries, LIBs35,36, and capacitors, LICs5). The overall efficiency for energy conversion and storage (ηoverall) has been calculated at different light intensities, as summarized in Fig. 6b. The highest ηoverall is achieved at a light intensity of 4 W cm−2 (corresponding to typical indoor-ambient lighting conditions), reaching a remarkable 11.95%. Such a high overall efficiency and excellent indoor light performance can be attributed to the high current tolerance and high-energy storage efficiency (ηstorage) of our ASC, where the ηstorage is calculated to be ~80%. To further verify the superiority of our solar-charging system, a GaAs-ASC integrated device was fabricated by combining GaAs solar cells with assembled ASCs, demonstrating a record high ηoverall of 17.57% under 1000 W m−2 (Supplementary Fig. 19). Such a remarkable overall efficiency can be attributed to the high conversion efficiency of the GaAs solar cell (25.88%) and the high-energy storage efficiency of the ASC (67.90%). Figure 6c draws comparisons of ηoverall between our integrated unit and state-of-the-art solar-charging systems. It is obvious that the ηoverall of our Si solar cell/ASC and GaAs solar cell/ASC devices outperform the other integrated systems, such as a Si solar cell integrated LIB (c-Si-LIB, 7.61%) and a perovskite solar cell combined with a LIC (PSC-LIC, 8.41%). Detailed comparisons of the key parameters (overall efficiency, output voltage and endurance current) between the current work and other reported studies in the field of solar-charging self-powered systems is provided in Supplementary Table 4.
We then considered the practical uses of our system by assembling a flexible solar-charging integrated unit according to the configuration depicted in Fig. 1a. Notably, a flexible amorphous Si solar cell functioned as the PV module (Supplementary Fig. 20a, b). The VN//MnO2 MASC was printed directly on the bottom of the solar cell, which is buffered by a polyimide (PI) layer. Figure 6d illustrates the solar-charging/discharging curves of our flexible integrated device. Under the same solar-charging condition of 4 W cm−2, it exhibits a favorable rate performance. The ηoverall of such a flexible system reaches 5.2% (Supplementary Fig. 20c). Despite being not as high as our rigid integrated unit, this is still superior to most reported flexible photo-charging self-powered systems4,37,38,39,40,41 (see Supplementary Table 5). To envisage realistic wearable applications, we further evaluated the mechanical stability of the integrated solar-charging self-powered units. Figure 6e shows the solar-charging (4 W cm−2)/discharging (1 mA cm−2) profiles under bending angles of 0°, 90°, and 180° (as displayed by the digital photos). The observation of increased solar-charging duration as a function of bending can be mainly attributed to the decrease in the effective area of illumination of a bent solar cell. Under this circumstance, the discharge energy, indicated by the discharging time, remains constant, demonstrating good flexibility of our self-powered unit. A mechanical durability test was also carried out by repeatedly bending the integrated device at 90° for 100 cycles (Fig. 6f,inset). The capacitance retention reached 94% and 80% after 10 and 100 bending cycles, respectively. In further tests, various flexible conditions were implemented to verify the mechanical robustness of our devices (Supplementary Fig. 21). Before and after folding, rolling, and waving deformations, the integrated unit exhibited a capacitance retention of 97.50%, 85.22%, and 93.04%, respectively. All these provide evidence for the good flexibility of our self-powered unit for practical applications.
Figure 6g further presents the photo-charging/discharging cycling performance tested at a light intensity of 4 W cm−2 and a discharge current density of 1 mA cm−2, with the inset showing the first 10 cycles and last 10 cycles of photo-charging/discharging curves. Remarkably, our integrated unit maintained outstanding cycling stability with a surprisingly high capacitance retention of 98.7% after 100 cycles, thus demonstrating excellent robustness and mechanical stability. It is anticipated that our integrated solar-charging self-powered units with good flexibility, long cycle life, and high safety will be viable for many wearable scenarios. Figure 6h shows a proof-of-concept demonstration. The integrated unit can be fully charged when exposed to either natural sunlight or outdoor lighting (i.e., during the daytime). The flexible and even rollable feature of such a power unit enables the direct wearing on clothes or application to bags as an efficient self-powered energy source. The energy stored in the solar-charged MASC can be ultimately utilized to power a light-emitting-diode panel, especially for indoor use during night time.
In summary, a highly flexible, safe, and durable solar-charging self-powered integrated unit has been developed. By synergistically combining an in-plane asymmetric printing technology with a multivalent ion electrochemical energy storage technology, the thus-derived integrated units show outstanding photo-charging cyclic stability (up to 98.7% capacitance retention after 100 cycles), with tolerance for a wide variation in current (from 1.6 to 114 mA cm−2), and favorable energy management for wearable devices. Moreover, the pseudo-capacitive intercalation/de-intercalation reaction mechanism of Mg2+ ions in VN electrodes has been elucidated using operando XRD and ex situ XPS, explaining both high energy density (13.1 mWh cm−3) and high power density (440 mW cm−3) of the VN//MnO2 ASCs. Such ASCs based on multivalent neutral ion electrolytes offer new insights into the design of high-energy, long-life, and safe energy sources toward the ultimate goal of creating light weight and wearable smart electronics.
Preparation of VN and MnO2@C electrode materials
Ammonium metavanadate was dissolved in 135 mL of deionized water and 15 mL of ethanol by stirring, followed by the addition of hydrochloric acid (1 mol L−1) to adjust the pH value of the solution to 2.0. The mixture was then transferred into a Teflon-lined autoclave and kept at 180 °C for 24 h. After cooling down to room temperature, a nanobelt-like VO2 product was obtained upon washing and drying. Finally, VN nanowires were produced by annealing the above-synthesized VO2 in pure NH3 at 600 °C for 3 h. As for the MnO2@C synthesis, 2 mL of an aqueous GO suspension (5 mg mL−1) was added into 58 mL of deionized water, followed by the addition of KMnO4 (316 mg) and urea (1 g). After stirring for 20 min, the above solution was transferred into a Teflon-lined autoclave and kept at 120 °C for 12 h. Nanoflower-like MnO2@C was readily obtained after washing and drying.
Preparation of MgSO4-PAM gel electrolyte
Three grams of starch was dissolved into 30 mL of deionized water by vigorously stirring at 100 °C for 1 h. After cooling, 5 g of acrylamide monomer, 25 mg of NH4S2O8, and 3 mg of N,N′-methylenebisacrylamide were added. The solution was stirred at room temperature for 2 h, followed by the elimination of surface bubbles under vacuum. The solution was then poured into a mold of a specific thickness and heated at 80 °C for 1 h. The as-prepared PAM gel was then immersed into 1.0 M MgSO4 electrolyte for more than 24 h to reach the ion balance point.
Assembly of quasi-solid-state ASCs
Mg ion quasi-solid-state ASCs were assembled using a typical coin cell structure. The negative electrode was prepared by casting onto Ti mesh a slurry containing the active material VN, conductive carbon (Super P), and binder (PVDF) in a mass ratio of 8:1:1. The mass loading was adjusted to 5–6 mg cm−2. The MnO2@C positive electrode was fabricated using a similar method, with the mass ratio at 7.5:2:0.5. The MgSO4-PAM gel was employed as the electrolyte. The optimized mass ratio of the positive and negative electrode was 1:2 (Supplementary Fig. 22). The thickness of the negative electrode, the positive electrode, and the gel electrolyte were 50, 50, and 200 μm, respectively. Moreover, a liquid electrolyte-based ASC was assembled as a control by using glass fiber as the separator with a liquid electrolyte.
The capacitance is calculated using the following equations:
According to the CV curves
In the three-electrode system, C is the capacitance (F), ν is scan rate (V s−1), I is the current response (A), V1(V2) is the starting and ending voltage (V), and ΔV is the voltage window (V). For the single electrode, the specific capacitance is calculated according the following equation:
where Cm is the mass specific capacitance (F g−1), C is the capacitance (F), and m is the mass of active material (g; without the consideration of binders and conductive agents).
In the two-electrode system, the electrochemical performance is calculated according to the GCD curves
where C is the capacitance (F), I is the discharging current (A), t is the discharging time (s), and ΔV is the voltage window (V). For the device, the specific capacitance is calculated according the following equation:
where Cm(s) is the mass or area specific capacitance (F g−1 or F cm−2), m is the total mass of positive and negative active material (g), s is the area of positive or negative electrode (cm−2, the area of positive and negative electrode is the same), and C is the capacitance (F).
The energy density (E) and power density (P) can be derived according to the following equations:
where Em is the mass energy density (Wh kg−1), Cm is the mass specific capacitance (F g−1), and V is the voltage (V).
where Ev is volume energy density (Wh cm−3), Cv is the volume specific capacitance (F cm−3, the volume is the product of electrode area and thickness, which includes the thickness of the positive electrode, the gel electrolyte, and the negative electrode), and V is the voltage (V).
As for the power density, the calculated equation is
where P is the power density (W kg−1 or W cm−3), E is the energy density (Wh kg−1 or Wh cm−3), and t is the discharging time (h).
Construction of flexible MASCs via printing
Flexible MASCs were constructed via a sequential screen-printing method. First, the PI substrate was treated with an O2 plasma. The as-treated substrate was subjected to a DC sputtering of gold for 15 min, where a printing mask was used to outline the gold deposition. Next, the VN electrode was printed with a slurry containing 80% VN, 10% conductive carbon black and 10% LA132. After drying, a second printing was applied to create the MnO2 electrode (75% MnO2@C, 15% Super P, and 10% LA132). A gel electrolyte was then coated over the patterned electrodes, with copper tape employed as the current collectors. Finally, the entire device was wrapped in a commercial thermoplastic PET film (see Supplementary Note 2 for the printing details). The encapsulation process is described as follows: First, the Cu conductive tape was pasted over the lead, the gel electrolyte was then coated on the printed pattern. Second, the micro-supercapacitor was placed between two plastic films and sealed by thermoplastic sealing. Finally, the tip of the lead was fixed using an AB glue (Supplementary Fig. 23).
Assembly of flexible solar-charging integrated units
To assemble the flexible self-powered units, flexible commercial amorphous Si solar cells were used as the energy-harvesting module. To avoid the non-smooth surface of the flexible solar cell, acrylic double-sided tape was first pasted onto the backside of the solar cell. Then, the cleaned PI substrate was attached to the other side of the acrylic tape, which was used for the printed substrate of the MASCs. After that, the MASC was fabricated by screen-printing. The gel electrolyte was then coated on the micropattern and the MASC was sealed using plastic film. Finally, the self-powered unit was packaged using the same plastic film (see Supplementary Fig. 24). To reach the matched open circuit voltage, two solar cells were connected in series to power a MASC module.
The overall efficiency of energy conversion and storage (ηoverall) can be calculated according to the following equation:
where E, P, S, and t are the discharge energy after solar-charging (Wh), the light intensity (W m−2), the effective area of solar cell (m2), and the duration of solar-charging (h), respectively.
The morphologies of samples were characterized by a Hitachi SU8010 scanning electron microscopy. STEM and HRTEM images were obtained on a Cs-corrected FEI Titan transmission electron microscopy operated at 300 kV. XPS spectra (including ex situ XPS analysis) were collected using an Escalab 250Xi Spectrophotometer using a monochromatic Al-Kα X-ray source. XRD measurements (including operando XRD) were performed at a Bruker D8 Advance Diffractometer using Cu-Kα radiation (λ = 1.5406 Å). All the electrochemical data were measured by a CHI760E workstation (CH Instruments, USA). The three-electrode tests (CV, LSV, GCD) were performed utilizing an Ag/AgCl reference electrode and a graphite rod counter electrode.
The data supporting the findings of this work are available within the article and its Supplementary Information files. All other relevant data supporting the findings of this study are available from the corresponding author on request.
Park, S. et al. Self-powered ultra-flexible electronics via nano-grating-patterned organic photovoltaics. Nature 561, 516–521 (2018).
Li, C. et al. Wearable energy-smart ribbons for synchronous energy harvest and storage. Nat. Commun. 7, 13319 (2016).
Shao, Y. et al. Design and mechanisms of asymmetric supercapacitors. Chem. Rev. 118, 9233–9280 (2018).
Zhang, F. et al. Highly flexible and scalable photo-rechargeable power unit based on symmetrical nanotube arrays. Nano Energy 46, 168–175 (2018).
Li, C. et al. Flexible perovskite solar cell-driven photo-rechargeable lithium-ion capacitor for self-powered wearable strain sensors. Nano Energy 60, 247–256 (2019).
Dong, L. et al. Multivalent metal ion hybrid capacitors: a review with a focus on zinc-ion hybrid capacitors. J. Mater. Chem. A 7, 13810–13832 (2019).
Li, K. et al. Aluminum-ion-intercalation supercapacitors with ultrahigh areal capacitance and highly enhanced cycling stability: power supply for flexible electrochromic devices. Small 13, 1700380 (2017).
Song, Y. et al. Synchronous immobilization and conversion of polysulfides on a VO2–VN binary host targeting high sulfur load Li–S batteries. Energy Environ. Sci. 11, 2620–2630 (2018).
Lu, X. et al. High energy density asymmetric quasi-solid-state supercapacitor based on porous vanadium nitride nanowire anode. Nano. Lett. 13, 2628–2633 (2013).
Yuan, C. et al. Investigation of the intercalation of polyvalent cations (Mg2+, Zn2+) into λ-MnO2 for rechargeable aqueous battery. Electrochim. Acta 116, 404–412 (2014).
Augustyn, V. et al. High-rate electrochemical energy storage through Li+ intercalation pseudocapacitance. Nat. Mater. 12, 518–522 (2013).
Wang., J. et al. Pseudocapacitive contributions to electrochemical energy storage in TiO2 (anatase) nanoparticles. J. Phys. Chem. C. 111, 14925–14931 (2007).
Li, K. et al. Lattice-contraction triggered synchronous electrochromic actuator. Nat. Commun. 9, 4798 (2018).
Song, J. et al. Activation of a MnO2 cathode by water-stimulated Mg2+ insertion for a magnesium ion battery. Phys. Chem. Chem. Phys. 17, 5256–5264 (2015).
Song, Y. et al. Enhanced sulfur redox and polysulfide regulation via porous VN-modified separator for Li-S batteries. ACS Appl. Mater. Interfaces 11, 5687–5694 (2019).
Jia, Z. et al. Vertically aligned α-MnO2 nanosheets on carbon nanotubes as cathodic materials for aqueous rechargeable magnesium ion battery. Ionics 24, 3483–3491 (2018).
Sun, X. et al. Investigation of the mechanism of Mg insertion in birnessite in nonaqueous and aqueous rechargeable Mg-ion batteries. Chem. Mater. 28, 534–542 (2016).
Li, H. et al. MoS2 nanosheets with expanded interlayer spacing for rechargeable aqueous Zn-ion batteries. Energy Storage Mater. 19, 94–101 (2019).
Yan, Y. et al. Facile synthesis of vanadium metal-organic frameworks for high-performance supercapacitors. Small 14, 1801815 (2018).
Yang, Z. et al. Hierarchical nanostructured α-Fe2O3/polyaniline anodes for high performance supercapacitors. Electrochim. Acta 269, 21–29 (2018).
Lu, X. et al. Oxygen-deficient hematite nanorods as high-performance and novel negative electrodes for flexible asymmetric supercapacitors. Adv. Mater. 26, 3148–3155 (2014).
Zeng, Y. et al. Advanced Ti-doped Fe2O3@PEDOT core/shell anode for high-energy asymmetric supercapacitors. Adv. Energy Mater. 5, 1402176 (2015).
Zhai, T. et al. Oxygen vacancies enhancing capacitive properties of MnO2 nanorods for wearable asymmetric supercapacitors. Nano Energy 8, 255–263 (2014).
Liu, Y. et al. Layered-MnO2 nanosheet grown on nitrogen-doped graphene template as a composite cathode for flexible solid-state asymmetric supercapacitor. ACS Appl. Mater. Interfaces 8, 5251–5260 (2016).
Huang, Z. H. et al. High mass loading MnO2 with hierarchical nanostructures for supercapacitors. ACS Nano 12, 3557–3567 (2018).
Li, R. et al. Conformal multifunctional titania shell on iron oxide nanorod conversion electrode enables high stability exceeding 30000 cycles in aqueous electrolyte. Adv. Funct. Mater. 28, 1800497 (2018).
Genovese, M. et al. Ultrathin all-solid-state supercapacitor devices based on chitosan activated carbon electrodes and polymer electrolytes. Electrochim. Acta 273, 392–401 (2018).
Xiao, X. et al. Salt-templated synthesis of 2D metallic MoN and other nitrides. ACS Nano 11, 2180–2186 (2017).
Jost, K. et al. Knitted and screen printed carbon-fiber supercapacitors for applications in wearable electronics. Energy Environ. Sci. 6, 2698–2705 (2013).
Zhang, Y. Z. et al. Printed supercapacitors: materials, printing and applications. Chem. Soc. Rev. 48, 3229–3264 (2019).
Li, D. et al. A simple strategy towards highly conductive silver‐nanowire inks for screen‐printed flexible transparent conductive films and wearable energy‐storage devices. Adv. Mater. Technol. 4, 2698–2705 (2019).
Zhang, Y. Z. et al. A simple approach to boost capacitance: flexible supercapacitors based on manganese oxides@MOFs via chemically induced in situ self-transformation. Adv. Mater. 28, 5242–5248 (2016).
Guo, R. et al. In-plane micro-supercapacitors for an integrated device on one piece of paper. Adv. Funct. Mater. 27, 1702394 (2017).
Zhang et al. MXenes stretch hydrogel sensor performance to new limits. Sci. Adv. 4, eaat0098 (2018).
Um, H.-D. et al. Monolithically integrated, photo-rechargeable portable power sources based on miniaturized Si solar cells and printed solid-state lithium-ion batteries. Energy Environ. Sci. 10, 931–940 (2017).
Xu, J. et al. Efficiently photo-charging lithium-ion battery by perovskite solar cell. Nat. Commun. 6, 8103 (2015).
Chai, Z. et al. Tailorable and wearable textile devices for solar energy harvesting and simultaneous storage. ACS Nano 10, 9201–9207 (2016).
Dong, P. et al. A flexible solar cell/supercapacitor integrated energy device. Nano Energy 42, 181–186 (2017).
Lechêne, B. P. et al. Organic solar cells and fully printed super-capacitors optimized for indoor light energy harvesting. Nano Energy 26, 631–640 (2016).
Gurung, A. et al. Highly efficient perovskite solar cell photocharging of lithium ion battery using DC-DC booster. Adv. Energy Mater. 7, 1602105 (2017).
Liang, J. et al. An all-inorganic perovskite solar capacitor for efficient and stable spontaneous photocharging. Nano Energy 52, 239–245 (2018).
This work was financially supported by the National Natural Science Foundation of China (51702225), National Key Research and Development Program (2016YFA0200103), and Natural Science Foundation of Jiangsu Province (BK20170336). The authors also acknowledge support from the Suzhou Key Laboratory for Advanced Carbon Materials and Wearable Energy Technologies, Suzhou, China and the Dr. Myung Ki Hong Chair in Materials Innovation (to R.B.K.).
The authors declare no competing interests.
Peer review information Nature communication thanks anonymous reviewers for their contribution to the peer review of this work. Peer review reports are available.
Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
About this article
Cite this article
Tian, Z., Tong, X., Sheng, G. et al. Printable magnesium ion quasi-solid-state asymmetric supercapacitors for flexible solar-charging integrated units. Nat Commun 10, 4913 (2019). https://doi.org/10.1038/s41467-019-12900-4
Nano-Micro Letters (2021)
Pseudocapacitive desalination via valence engineering with spindle-like manganese oxide/carbon composites
Nano Research (2021)
Journal of Solid State Electrochemistry (2021)
Zn Ion-Doped Amorphous NiWO4 Nanospheres as Cathode Material for High-Performance Asymmetric Supercapacitors
Journal of Electronic Materials (2021)
3D Printing of NiCoP/Ti3C2 MXene Architectures for Energy Storage Devices with High Areal and Volumetric Energy Density
Nano-Micro Letters (2020)


text:
Only logged in customers who have purchased this product may leave a review.
Scentos Scented Twisted Crayons (8 Pack)
Delivery in 1 – 3 Working Days.
Let your kids indulge in hours of fun with this wonderful Scentos scented twisted crayons.
Twist up the fun and turn up the smells with Scentos twistable scented crayons. We’ve applied the same great nontoxic scent technology to crayons, and positioned them inside easy to use, clear twistable tubes. Each pack also comes with a clear reusable plastic pouch, allowing for clean and convenient fun, followed by easy storage. No more sharpening and no more broken crayons, Scentos twistable crayons are perfect for children and as you’ve come to expect, each brilliant colour is coupled with its own unique, long lasting scent, sure to inspire the artist in anyone!
- Orange / Orange
- Pink / Bubble Gum
- Red / Strawberry
- Yellow / Lemon
- Green / Green Apple
- Blue / Blueberry
- Purple / Grape
– Each of the 8 crayons has it’s own individual scent which is released as children use the pencils to colour and draw.
– You just twist the base to bring the crayon up ready for use.

domain: artistic


text:
From a Jeremy McCarter's review of Stefan Kanfer's biography of Marlon Brando:
International Herald Tribune, January 3-4, 2008
'Somebody': Admiring Brando, even at his worst
By Jeremy McCarter
Friday, January 2, 2009
Somebody The Reckless Life and Remarkable Career of Marlon Brando By Stefan Kanfer Illustrated. 350 pages. Alfred A. Knopf, $26.95; Faber and Faber, £20.
On the night "A Streetcar Named Desire" opened on Broadway, Tennessee Williams sent his young leading man a rapturous telegram: "From the greasy Polack you will someday arrive at the gloomy Dane for you have something that makes the theater a world of great possibilities." Looking back now, you might describe that as, word for word, the most poignant couple of lines Williams ever wrote. For one thing, "greasy Polack" reflects a pinched view of what Marlon Brando achieved. Stanley Kowalski is a brute, a vulgarian and a rapist, but Brando also gave him a canny intelligence and enough charm that the play's audiences joined him in laughing at Williams's heroine, Blanche DuBois, every night. Brando's looks also helped: thanks to the poetic face he carried atop his muscled body, his loutish Stanley could have passed for a slumming demigod.
In the end, of course, Brando never played Hamlet, nor did he exhaust the "great possibilities" that Williams and so many others detected. Though he liberated generations of actors when he brought a fresh vulnerability to his early film roles - a majestic four-year run culminating in his 1954 portrayal of Terry Malloy, the anguished ex-boxer in "On the Waterfront" - Brando had barely reached his 30s before he entered his Elvis-in-the-jumpsuit phase. He picked bad projects and gave indifferent performances, however speckled they might be with astonishing flashes. His weight ballooned, and he refused to learn his lines. Acting itself seemed ridiculous to him: "a bum's life," useful primarily as a way to pay his shrink's bills.
After more than a decade of this dud work, Brando made an astounding comeback, putting out "The Godfather" and "Last Tango in Paris" in 1972. But the eccentric decay soon resumed. Nobody needed to see his lip-lock with Larry King, or his various family tragedies, or "The Island of Dr. Moreau."
Why do the great ones so rarely have the capacity to handle their genius? Brando is not the first talent to invite the question - his contemporary Orson Welles preceded him on the path of brilliant promise, wobbly mature work and self-sabotaging obesity - but Stefan Kanfer helps establish him as the all-time Exhibit A. His new biography, "Somebody: The Reckless Life and Remarkable Career of Marlon Brando," is not as exhaustive as Peter Manso's 1,100-page endeavor, or as concisely illuminating as Patricia Bosworth's more recent short book, or as engaging as Brando's own memoir. But it is the first serious biography to appear since Brando's death in 2004, and therefore the first account to corral in one place the whole story of what Kanfer aptly calls "a life of ludicrous excess, outlandish triumphs and appalling sorrows."
The combination didn't take long to emerge. Brando arrived in New York in 1943 at the age of 19, a military school dropout from a busted Midwestern family. (His mother, a frustrated actress, drank; his father derided and brutalized him, reacting to his 4-F status in the war by sneering, "Is there anything else you could fail at?") But Brando found his way to the classes of the legendary Stella Adler, who soon declared that "this puppy thing will be America's finest actor."
His time at the New School is important and poorly understood. Though Brando's talent is frequently treated as a vindication of the Method, the memory-mining technique that Lee Strasberg sloppily adopted from the great Russian director Konstantin Stanislavsky, Kanfer points out that Brando despised Strasberg. He learned much more from Adler, though she knew better than to take credit for his success. Stanislavsky's system is meant to help actors find the inspiration that geniuses feel with no system at all. Even as a novice, Brando made other actors look as if they were painting with rollers.
Radical as Brando's charismatic immediacy seemed to people on Broadway - and, beginning in 1950, to movie audiences - he wasn't the only one making such a breakthrough. Around the same time, Jackson Pollock's art and Charlie Parker's music reflected a similar mix of casualness and intensity, technique and spontaneity. His personal life also grew chaotic enough to rival those of his fellow modernist giants, as he roamed nocturnal New York (particularly its minority neighborhoods), tended a pet raccoon named Russell and bedded everything that moved. But unlike Parker and Pollock - or his only acting rivals in those years, James Dean (who revered him) and Montgomery Clift - Brando didn't destroy himself, at least not all at once. He let himself be humiliated by Truman Capote in a 1957 interview in The New Yorker; unwisely entrusted his money to his father, who lost it; and collected enough lovers and children (at least 11, by the end) to keep him in almost constant need of cash.
It is customary at this point to tut-tut about the ways that American culture forces its leading lights to work on execrable junk to remain solvent. But Kanfer, who has written biographies of Groucho Marx and Lucille Ball, notes that Brando made dumb choices, turning down premieres of "The Iceman Cometh" and "Present Laughter" on Broadway and "Lawrence of Arabia" and "Butch Cassidy and the Sundance Kid" on screen.
The most tantalizing offer of all came from John Gielgud. After playing Cassius to Brando's Marc Antony in the film of "Julius Caesar," he invited the young American to join him and Paul Scofield for a full season in London. Here, in Brando's prime, and with the best collaborators imaginable, was a path that led to the long-awaited Hamlet. Instead, he made "The Wild One" - an iconic film, but still laughably unworthy of his talent.
However much he abused them, Brando's gifts survived the rot of his later films. Watch, in "The Godfather," how he sniffs a rose, or strokes a cat, or slaps a co-star - all on-the-spot inventions of a fertile creative mind. To the end, he was "the same man with the same extraordinary aptitude for inhabiting a character, just older and heavier," Kanfer writes. Having outgrown the handsome distress of youth, he "still allowed viewers to see the whole Brando, a man at risk, a vastly overweight, compulsive figure for whom meals had become what strong drink had been to his parents."

domain: library


text:
There is evidence that dates back more than 10,000 years which suggests that humans were bonding with canines even back then. But have you ever wondered why we are able to form such strong bonds with dogs? A recent study gets to the bottom of that question.
The study, performed at Monash University in Melbourne, Australia and published in the February 2015 edition of the journal Animal Cognition, suggests that oxytocin could be the answer. The so-called “love hormone” has been extensively studied in humans and it has been proven to increase the trust level of our species. It is also the chemical that fosters the bond between mothers and their babies.
A graduate student in biology, Jessica Oliva, is the lead author of the study. Oxytocin is a chemical that is released by the brain in reaction to close contact like cuddling. Oliva’s study shows that this chemical may be responsible for the inter-species bonding between humans and dogs, and it could be the reason that dogs pay such close attention to our social cues.
RELATED: How to Train a Puppy
In the study, 62 male and female domesticated dogs of varying breeds were used. The dogs were encouraged to find food in one of two bowls by following the hand signals of a human. They had never met the human before this study.
During the first phase of the research, the dogs were tested after being given a nasal spray containing oxytocin. A researcher stood in the middle of the room and pointed to the bowl that contained the food. After the oxytocin had worked its way out of the dog’s system, they were given a nasal spray containing only salt water and had to perform the same experiment again.
Each time the dogs were rated on their ability to find the food in the bowl. Researchers found that the dogs performed better after receiving the oxytocin spray. Not only did they perform better that day, but the performance boost continued for up to 15 days after the oxytocin spray was used.
The fact that they followed human cues better after inhaling oxytocin, suggests that the hormone enhances the dog’s ability to act on human social cues. Oliva believes that this suggests that oxytocin played a key part in the domestication of canines.
This research is certainly interesting, but it is just the first step in figuring out how oxytocin actually affects the canine brain. Experts in the field are hoping that more research will be done to look at the receptors in the dogs’ brain, and research also needs to be performed to measure the exact levels of oxytocin in the animals system during the trials.

domain: biology


text:
Ever wonder what it would be like to have a pair of shoes that could match any piece of clothing you own?
Just take a look at Jimmy Butler's closet.
(photo via Redfin
The former Bulls swingman, whose River North mansion recently went on the market for $5 million after he was traded to the Minnesota Timberwolves, has a room filled to the brim that houses nothing but sneakers — which are predominately Jordan Brand as Butler is signed to the iconic company.
"It's really all Jordan. I rep that brand," Butler said via Complex Magazine. "I don't wear too many Nikes. That's it. I'm a Jordan guy, head to toe, unless I got on moccasins."
Don't expect Butler to leave any of his shoes behind when he makes the move to Minnesota.
However, his fish tank may be another story.
Butler was the focal point of an episode of "Tanked" on Animal Planet in 2015, in which he had a 6,000-pound boombox-shaped aquarium installed in his house.
According to DNAinfo, via Dream Town Realty, there's no word on whether or not the fish tank is included in the listing price.
Check out more photos of Butler's six-bedroom, 10,000-square foot house, via Redfin below:
The latest Derrick Rose report says the 28-year-old guard will end up teaming up with LeBron James.
According to ESPN's Adrian Wojnarowski, Rose is leaning toward signing with the Cleveland Cavaliers over the Los Angeles Lakers. Discussions have been for a one-year, $2.1 million deal.
The free agent guard is meeting with Cavs officials in Ohio on Monday, according to Woj.
Rose's decision to sign with the Cavs makes more sense than the Lakers, especially after last week's report that Kyrie Irving requested a trade out of Cleveland. A minimum deal for Rose would also be a steal for the Cavs, who are seeking some solid production at a low cost.
In 64 games last season with the New York Knicks, Rose averaged 18 points, his best since the 2011-12 season with the Bulls.
CSN Chicago's Bulls analyst Kendill Gill played in The Big 3 in Chicago's UIC Pavilion on Sunday and gave CSN some inside access.
Gill was mic'd up in warm-ups and talked to CSN's Mark Schanowski after the game. Gill's Team Power picked up another win to improve to 3-1.
Watch the video above to see the behind the scenes footage and the interview with Schanowski.

domain: sports


text: Transport Canada has just approved a flight and even mapping program at 3 of its job sites, and even starting this month the business expects to carry out drone trips a minimum of as soon as a week. Wait for your Incredible MPV Video clip right here! Canada’s AV regulation, in place considering that 2008 and also modified in 2010, makes it possible for home owner like Scott McTavish to make a living operating drones. The flourishing interest in office drones has actually also profited pastime flyers. Once Deliver Canada authorizes an application, the drone is clear to fly. Royal Dutch Covering PLC has actually examined unmanned plane for land surveying at its Jackpine and also Muskeg Stream oil sands mines. Please see Transport diy drones Canada’s Drone Safety and security Video and also fly properly. Scripps is ways to make Canadian airspace risk-free with unmanned cars in the mix.

domain: news


Lasers perform core material processing functions such as cutting, welding, drilling. And all with a precision that isn’t possible any other way. As technology advances, devices (and the parts therein) are increasingly miniaturised. The lasers we provide are responsible for the reliable production of micro parts for the solar, medical, electronic and automotive industries.
Fusing metals at such a tiny scale would be impossible without lasers. Let’s look at an example—medical device production. The first step might be to remove insulation from a thin wire before it’s cut or welded. Traditional welding would radiate so much heat as to destroy the whole part or product. With lasers, the energy is focused on the precise welding spot. The surrounding materials maintain their original characteristics, and the bond is reliable and repeatable.
Using lasers requires zero contact, unlike a traditional drill or saw. It’s impossible to find a drill bit at this miniature scale, let alone sharpen it. The benefit of the zero-contact approach is two-fold. First, the holes or cuts are precise with minimal burrs, heat-affected zone (HAZ) or debris. The walls are smooth. This level of precision means extra processing isn’t required, leading to greater efficiency in your production.
Secondly, the laser remains “sharp”—it’s not worn over time. We offer rugged laser solutions that stand up to rigorous manufacturing processes.
If we want smaller and more efficient devices (as we do), technology has to keep up with demand. The medical, electronic and automotive industries, in particular, rely on laser micromachining to produce high-quality devices and parts. If you have an application you need to fulfil and think that lasers could be the solution, talk to Raymax about our laser evaluation and process development services.
If the device you manufacture is made out of a combination of materials, that can pose a unique challenge. However, lasers can process different materials, including polymers, metals, ceramics, and even glass. You just have to find a solution that meets all your requirements. Here at Raymax, we’re the material interaction experts. We can help you solve your complex micro manufacturing dilemmas.
We supply many different lasers from a range of trusted companies for microprocessing. Optec, Lasea, Light Machinery, ATL, Amplitude, Trumpf, Edgewave, Laserline, Lumentum, TEEM, Thales Laser to name just a few. Raymax is different to many laser suppliers in that we offer research and evaluation facilities and services. We’ll help you identify the laser solution that works for your requirements.
We make laser light work for you. We’ve spent over 30 years demonstrating what’s possible with lasers. In doing so, we’ve helped modernise Australian and New Zealand industries. You’ll be working with a team of physicists and factory-trained engineers—leaders in the supply of laser solutions and photonics equipment. We’re experts in material interaction research. Wherever possible, you’ll be introduced to new technology that can improve operation in ways you might not have imagined possible.


Thierry Henry says he considered quitting international football because of the controversial goal that sent France to the World Cup finals at Ireland’s expense. The Barcelona forward’s blatant handball in the build-up to William Gallas’s extra-time equaliser last Wednesday night went unpunished and sent France through 2-1 on aggregate.
Henry has now claimed that, during reflections after the match, he seriously considered his future in the sport.
“Yes, I asked myself the question,” Henry said. “Without the support of my family, I perhaps would not have made the same decision. But I will always fight to the end - even if what just happened will be engraved. You can always forgive but you cannot always forget.”
He added: “After the 2006 World Cup, I thought…


text:
SAN FRANCISCO — Cindy Starfall will be dancing with Marica Hase at the Crazy Horse Gentlemen’s Club in San Francisco this Thursday, Aug. 18 as well as Friday, Aug. 19 and Saturday, Aug. 20. Starfall and Hase will perform six duo shows altogether over the three nights.
“It’s always a treat to go to San Francisco,” Starfall said. “The people are incredible, and the Crazy Horse is a great venue. The fans are going to have a great time. I look forward to seeing all my Club Starfall members at the show.”
Between sets, Starfall will be available for fan photos, autographs and VIP lap dances.
The Crazy Horse is located at 980 Market St.
Starfall is featured with “Workaholics” actor Eric Griffin in a photo shoot for the October issue of Hustler Magazine. Griffin time from the production of Comedy Central’s “Workaholics” to talk to Hustler about his career and the impact of the show.
The October issue of Hustler Magazine is available now, and the article can be found at this link.
For more information on Hase, follow her on Twitter.


text:
Income Tax Act provides number of deductions or schemes for tax saving. These are schemes in which you can invest and avail tax deduction. One of the deductions is under Section 80D in which a taxpayer invests their money in medical insurance premium and that amount can be availed as mediclaim deduction. This had been introduced to promote medical insurance and encourage public to buy medical insurance for future safety.
Eligibility to Avail Mediclaim Deduction
Any individual/HUF can avail deduction under section 80D. Also a person can invest money or can buy insurance on the name of
- his spouse,
- dependent child,
- dependent /independent parents
and he can still avail the deduction. The deduction of mediclaim insurance policy under section 80D is over and above the deduction availed under section 80C/ 80CCD/ 80CCC.
Quantum of deduction
Individuals/HUF: any person who bought mediclaim insurance policy can avail the deduction under section 80D maximum to –
- Rs 25000 if person’s age is less than 60 years, and
- Rs 50000 if person’s age is more than 60 years (i.e., senior citizen and very senior citizen).
Therefore, if a person is senior citizen and buy policies for himself and for his parents who are senior citizen as well, in such case that person can claim total deduction of Rs. 1,00,000.
Preventive Health Checkups
Preventive health check-up as the name itself suggests is an expense which one incurs on preventive measures for early detection and safeguard against possible exposure to any disease in future.
Any expense made by taxpayer towards preventive health check-ups will be eligible to a deduction of up to Rs.5,000, which is within the overall limit of Rs.25,000/ 50000.
This deduction can also be claimed either by the individual for himself, spouse, dependent children or parents. The payment for preventive health check-up can be made in cash.
Lump sum amount of Mediclaim Insurance Policy
If a person has paid lump sum amount in a single year for the policy which is more than one year premium then the whole amount will not be allow as a deduction in same year. The deduction will be available on a fractional basis i.e amount will be allocated to each year on the basis of total amount divided by number of years.
The resulted amount will be allowed as deduction in a single year and remaining amount in another years. Also, that amount of deduction will subject to the limit given under section 80D i.e. amount of deduction shall not be more than Rs 25,000 or Rs 50,000.
There is no document specified by Income Tax Act, 1961 to avail the mediclaim deduction under section 80D. But it will be advisable to keep the necessary document as a evidence such as medical bills, invoice or payment slip of medicine, insurance policy paper, etc in case you have been asked for proof.
If you don’t have any documents then it will become difficult to proof the deduction. However you can ask for a time to arrange papers and evidence.
Mode of payment
In case of payment of medical insurance, the payment should be made by way other than cash. If you make payments by cash than the whole expenditure will be disallowed. That means a person will not be able to claim any deduction. Therefore person can use net banking, debit card, credit card, UPI etc. for payment.
Important points to keep in mind
A. Payment should be made by any mode other than cash except for preventive health checkups.
B. Meaning of Senior citizen- Senior Citizen means an individual resident in India of the age of 60 yrs or more during the relevant financial year.
C. Premium paid on behalf of a brother, sister, grandparents, aunts, uncles or any other relative cannot be claimed as a deduction for taking tax benefit.
D. In the case of part payment by you and a parent, both of you can claim a deduction to the extent paid by each.
The author of above article is Shruti Jain.
Disclaimer:The article or blog or post (by whatever name) in this website is based on the writer’s personal views and interpretation of Act. The writer does not accept any liabilities for any loss or damage of any kind arising out of information and for any actions taken in reliance thereon.
Also, www.babatax.com and its members do not accept any liability, obligation or responsibility for author’s article and understanding of user.
For Advertising with us-
- Mail us at [email protected]
- Whatsapp us at 7024984925

domain: law