Multiplying Light Harvest Driven by Hybrid-Reflections 3D Electrodes Achieves High-Availability Photo-Charging Zinc-Ion Batteries

Independent photo-charging technologies based on aqueous zinc-ion batteries (ZIBs) are promising candidates for next-generation renewable energy systems. The conflict between light utilization and electrochemical performance in the planar electrode severely limits the availability of photo-charging ZIBs. Herein, 3D light-trapping structures (LTSs) are proposed and applied in a rigid VO₂/C@SiCuOC electrode. A hybrid-reflection effect driven by LTSs is employed to improve light-harvesting efficiency. The suitable energy levels of VO₂ and C ensure charge transport, while the rigid SiCuOC support meets the stability requirements. Such a 3D VO₂/C@SiCuOC electrode exhibits a multiplying photo-response current density of 42.2 µA cm⁻² (≈400% of the plate) and delivers a higher energy density (0.19 mWh cm⁻² at 0.51 mW cm⁻²). More importantly, in a realistic environment (dark for 16 h and light for 8 h), the photo-charging ZIBs integrated into a roof exhibit an exciting open circuit voltage of 3.176 V (three in series) and supply electricity continuously. The high strength (over 9 MPa) of the photo-charging ZIBs inherited from the 3D rigid electrode further enables its practical application. The enhanced performance of the photo-charging ZIBs obtained from structural optimization provides unique inspiration for next-generation clean energy harvest/storage systems.