Molybdenum Disulfide–Zinc Oxide Photocathodes for Photo-Rechargeable Zinc-Ion Batteries

Abstract

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

Integrated Photovoltaic Charging and Energy Storage Systems: Mechanism, Optimization, and Future

“…[ 67 ] Boruah et al also chose MoS 2 as the photoactive cathode material for the zinc ion battery, in which ZnO was designed as the electron transport and hole blocking layer for the photoelectrode material ( Figure a–c). [ 135 ] The photoconversion efficiencies of the photocathode reaches 0.2% and The capacity increased by 38% under illumination. The main reason is that the conduction band of ZnO is closer to that of MoS 2 than that of MoO x , and the energy level between MoS 2 /ZnO photoelectrodes is better matched, and it is easier for carriers to transfer from high energy level to low energy level after being excited by light (Figure 9d,e).…”

“…Reproduced with permission. [ 135 ] Copyright 2021, American Chemical Society. f) Schematic illustration of our Photo‐LIB concept; Schematic representing the photocharging mechanism of Photo‐LIB.…”

“…Holes can oxidize the reduced cathode to the oxidized cathode due to the higher potential of the valence band (VB) of the semiconductor. On the other hand, the photogenerated electrons can promote the reduction reaction at the anode with the help of external [135] Copyright 2021, American Chemical Society. f) Schematic illustration of our Photo-LIB concept; Schematic representing the photocharging mechanism of Photo-LIB.…”

“…e) GCD curves at 100 mA g −1 in dark and illuminated states. Reproduced with permission [135]. Copyright 2021, American Chemical Society.…”

Photoelectrochemical energy storage materials: design principles and functional devices towards direct solar to electrochemical energy storage

“…The as-constructed battery could achieve ∼0.2% of solar-conversion efficiency and the battery capacity could be increased from 245 to 340 mA h g −1 when under illumination. 103…”