ABSTRACT
As electronic devices for aviation, space, and satellite applications become more sophisticated, built-in energy storage devices also require a wider temperature spectrum. Herein, an all-climate operational, energy and power-dense, flexible, in-plane symmetric pseudocapacitor is demonstrated with utmost operational safety and long cycle life. The device is constructed with interdigital-patterned laser-scribed carbon-supported electrodeposited V5O12·6H2O as a binder-free electrode and a novel high-voltage anti-freezing water-in-salt-hybrid electrolyte. The anti-freezing electrolyte can operate over a wide temperature range of -40-60 °C while offering a stable potential window of ≈2.5 V. The device undergoes rigorous testing under diverse environmental conditions, including rapid and regular temperature and mechanical transition over multiple cycles. Additionally, detailed theoretical simulation studies are performed to understand the interfacial interactions with the active material as well as the local behavior of the anti-freeze electrolyte at different temperatures. As a result, the all-weather pseudocapacitor at 1 A g-1 shows a high areal capacitance of 234.7 mF cm-2 at room temperature and maintains a high capacitance of 129.8 mF cm-2 even at -40 °C. Besides, the cell operates very reliably for over 80 950 cycles with a capacitance of 25.7 mF cm-2 at 10 A g-1 and exhibits excellent flexibility and bendability under different stress conditions.
ABSTRACT
Vanadium oxyhydroxide has been recently investigated as a starting material to synthesize different phases of vanadium oxides by electrochemical or thermal conversion and has been used as an aqueous zinc-ion battery (AZIB) cathode. However, the low-valent vanadium oxides have poor phase stability under ambient conditions. So far, there is no study on understanding the phase evolution of such low-valent vanadium oxides and their effect on the electrochemical performance toward hosting the Zn2+ ions. The primary goal of the work is to develop a high-performance AZIB cathode, and the highlight of the current work is the insight into the auto-oxidation-induced phase transition of VOOH to V10O24·nH2O under ambient conditions and Zn2+ intercalation behavior thereon as an aqueous zinc-ion battery cathode. Herein, we demonstrate that hydrothermally synthesized VOOH undergoes a phase transition to V10O24·nH2O during both the electrochemical cycling and aerial aging over 38-45 days. However, continued aging till 150 days at room temperature in an open atmosphere exhibited an increased interlayer water content in the V10O24·nH2O, which was associated with a morphological change with different surface area/porosity characteristics and notably reduced charge transfer/diffusion resistance as an aqueous zinc-ion battery cathode. Although the fresh VOOH cathode had impressive specific capacity at rate performance, (326 mAh/g capacity at 0.1 A/g current and 104 mAh/g capacity at 4 A/g current) the cathode suffered from a continuous capacity decay. Interestingly, the aged VOOH electrodes showed gradually decreasing specific capacity with aging at low current and however followed the reverse order at high current. At a comparable specific power of â¼64-66 W/kg, the fresh VOOH and aged VOOH after 60, 120, and 150 days of aging showed the respective energy densities of 208.3, 281.2, 269.2, and 240.6 Wh/kg. Among all the VOOH materials, the 150 day-aged VOOH cathode exhibited the highest energy density at a power density beyond 1000 W/kg. Thanks to the improved kinetics, the 150 day-aged VOOH cathode delivered a considerable energy density of 39.7 Wh/kg with a high specific power of 4466 W/kg. Also, it showed excellent cycling performance with only 0.002% capacity loss per cycle over 20â¯300 cycles at 10 A/g.
ABSTRACT
Developing high-performance, safer, and affordable flexible batteries is of urgent need to power the fast-growing flexible electronics market. In this respect, zinc-ion chemistry employing aqueous-based electrolytes represents a promising combination considering the safety, cost efficiency, and both high energy and high-power output. Herein, we represent a high-performance flexible in-plane aqueous zinc-ion miniaturized battery constructed with all electrodeposited electrodes, i.e., MnO2 cathode and zinc anode with polyimide-derived interdigital patterned laser-scribed carbon (LSC) as the current collector as well as the template for electrodeposition. The LSC possesses a cross-linked network of graphitic carbon sheet, which offers large surface area over low footprint and ensures active materials loading with a robust conductive network. The LSC with high zincophilic characteristic also offers dendrite-free zinc deposition with very low Zn2+ plating stripping overpotential. Benefitting from the Zn//MnO2-rich redox chemistry, the ability of the 3D LSC network to uniformly distribute reaction sites, and the architectural merits of in-plane interdigitated electrode configuration, we report very high capacity values of â¼549 mAh/g (or â¼523 µAh/cm2) and 148 mAh/g (or 140 µAh/cm2) at 0.1 A/g (0.095 mA/cm2) and 2 A/g (1.9 mA/cm2) currents, respectively. The device was also able to maintain a high capacity of 196 mAh/g (areal capacity of 76.19 µAh/cm2) at 1 A/g (0.95 mA/cm2) current after 1350 cycles. The flexibility of the device was demonstrated in polyacryl amide (PAM) gel polymer soaked with a 2 M ZnSO4 and 0.2 M MnSO4 electrolyte, which exhibited a comparable specific capacity of â¼102-110 mAh/g in flat condition and different bending (100° or 160° bending) conditions. The device does not use any conventional current collector, separator, and conductive or polymer additives. The overall process is highly scalable and can be completed in less than a couple of hours.
