Highest overall conversion efficiency for portable thin-film zinc-ion batteries photorecharged by flexible perovskite solar cells

The interconnection of flexible thin-film zinc-ion batteries (FTZIBs) and flexible perovskite solar cells presents an ideal system for portable photorechargeable power generation-storage system. However, the integration process of these two components still faces significant challenges. In this work, we develop a novel approach to enhance the integration compatibility between FTZIBs and flexible perovskite solar cells. Specifically, FTZIBs and flexible perovskite solar cells are fabricated on opposite sides of a polyimide (PI) substrate, aiming to improve the portability and compactness of the FTZIBs. By using Ag-Cu thin-film as the current collectors for the FTZIBs, not only suppress galvanic corrosion between the current collector and Zn but also ensure that the Ag-Cu-Zn thin-film electrode satisfies the Born-Huang stability criterion, significantly improved the electrochemical cycling stability and mechanical robustness of the thin-film electrodes. Additionally, a functional organohydrogel electrolyte with excellent mechanical strength, adhesion, and water retention is synthesized to suppress Zn dendrite formation and side reactions such as hydrogen evolution, enhancing the cycling stability and bendability of the FTZIBs. The resultant portable photorechargeable zinc-ion batteries (PZIBs) exhibit a high specific capacity of 250 mAh cm⁻³ and an overall conversion efficiency of 18.44 %, representing the best performance among similar systems.