Abstract
AbstractPhotovoltaics are an important source of renewable energy, but due to the intermittent nature of insolation, solar cells usually need to be connected to rechargeable batteries, electrochemical capacitors or other energy storage devices, which adds to the complexity and cost of these systems. In this work, a cathode design for photo‐rechargeable zinc‐ion batteries (photo‐ZIBs) is reported, that is inherently capable of harvesting sunlight to recharge without the need for external solar cells. The proposed photocathodes, comprising a composite of vanadium dioxide nanorods and reduced graphene oxide, are engineered to provide the necessary charge separation and storage for photocharging under illumination. The photo‐ZIBs achieve capacities of ≈282 mAh g−1 in the dark and ≈315 mAh g−1 under illumination, at 200 mA g−1, demonstrating the use of light not only to charge the devices, but additionally to enhance their capacity. The photo‐ZIBs also demonstrate enhanced high‐rate capabilities under illumination, as well as a capacity retention of ≈90% over 1000 cycles. The proposed photo‐ZIBs are considered a promising new technology for addressing energy poverty, due to their high performance and inherent cost‐efficiency and safety.
Highlights
Impressive, these systems often suffer from low capacities, poor cycling stability, and low energy conversion efficiency
Introduction[5] device that goes some way in addressing the above challenges and achieved conversion efficiencies of 1.2%, The development of off-grid energy harvesting and storage capacities of ≈140 mAh g−1, a capacity retention of ≈83% over systems is important to power stand-alone sensors and other 500 cycles, and relied on P3HT to support that photo-generated autonomous devices as well as for addressing energy poverty in charge separation process
Solar cells are oftentimes used in conjunc- anodes provide greater device stability and safety compared tion with batteries or supercapacitors to smooth out the intermit- to those using Li metal anodes
Summary
(photo-ZIB)[5] device that goes some way in addressing the above challenges and achieved conversion efficiencies of 1.2%, The development of off-grid energy harvesting and storage capacities of ≈140 mAh g−1, a capacity retention of ≈83% over systems is important to power stand-alone sensors and other 500 cycles, and relied on P3HT to support that photo-generated autonomous devices as well as for addressing energy poverty in charge separation process. As expected from the CV curves, the capacities of the photo-ZIBs are enhanced under illumination, for instance, the capacity increases from 282 to 315 mAh g−1 (11.7% enhancement) at 200 mA g−1 (Figure 4a) and from 71 to 134 mAh g−1 (88.7% enhancement) at higher specific currents of 20,000 mA g−1 (Figure 4b) This suggests that light can be used to recharge batteries and to increase high-rate performance, which is in agreement with the increase in zinc-ion diffusion discussed above. The resilience to change of the bandgap of VO2 in this work, is deemed advantageous for the operation of ZIBs, where the absorbance profile of the material, and the photo-enhancement, is unchanged, regardless of the state of charge This explains why increases in current are observed under illumination throughout the voltage range used in the CV and galvanostatic curves reported above.
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