Molybdenum\nDisulfide–Zinc\nOxide Photocathodes for Photo-Rechargeable Zinc-Ion Batteries

Abstract

Systems for harvesting\nand storing solar energy have found practical\napplications ranging from solar farms to autonomous smart devices.\nGenerally, these energy solutions consist of solar cells for light\nharvesting and rechargeable batteries to match the solar energy supply\nto consumption demands. Rather than having a separate energy harvesting\nand storing device, we report photo-rechargeable zinc-ion batteries\n(<i>h</i>ν-ZIBs) using a photoactive cathode composed\nof layer-by-layer grown zinc oxide and molybdenum disulfide. These\nphotocathodes are capable of harvesting solar energy and storing it\nin the same material and alleviate the need for solar cells or power\nconverters. The proposed photocathodes achieve photoconversion efficiencies\nof ∼1.8% using a 455 nm light source and ∼0.2% of solar-conversion\nefficiencies. Light not only allows photocharging but also enhances\nthe battery capacity from 245 to 340 mA h g^–1 (specific\ncurrent of 100 mA g^–1 and 12 mW cm^–2 light intensity at 455 nm). Finally, the proposed <i>h</i>ν-ZIBs also demonstrate a capacity retention of ∼82%\nover 200 cycles.