Photo-Assisted Chemical Self-Rechargeable Zinc Ion Batteries with High Charging and Discharging Efficiency

Chemical self-recharging zinc ion batteries (ZIBs), which are capable of auto-recharging in ambient air, are promising in self-powered battery systems. Nevertheless, the exclusive reliance on chemical energy from oxygen for ZIBs charging often would bring some obstacles in charging efficiency. Herein, we develop photo-assisted chemical self-recharging aqueous ZIBs with a heterojunction of MoS₂/SnO₂ cathode, which are favorable to enhancing both the charging and discharging efficiency as well as the chemical self-charging capabilities under illumination. The photo-assisted process promotes the electron transfer from MoS₂/SnO₂ to oxygen, accelerating the occurrence of the oxidation reaction during chemical self-charging. Furthermore, the electrons within the MoS₂/SnO₂ cathode exhibit a low transfer impedance under illumination, which is beneficial to reducing the migration barrier of Zn²⁺ within the cathode and thereby facilitating the uniform inserting of Zn²⁺ into MoS₂/SnO₂ cathode during discharging. This photo-assisted chemical self-recharging mechanism enables ZIBs to attain a maximum self-charging potential of 0.95 V within 3 hours, a considerable self-charging capacity of 202.5 mAh g^-1 and excellent cycling performance in a self-charging mode. This work not only provides a route for optimizing chemical self-charging energy storage, but also broadens the potential application of aqueous ZIBs.