Ag-Doping Effect on MnO 2 Cathodes for Flexible Quasi-Solid-State Zinc-Ion Batteries.

Rechargeable aqueous Zn/MnO₂ batteries are very potential for large-scale energy storage applications owing to their low cost, inherent safety, and high theoretical capacity. However, the MnO₂ cathode delivers unsatisfactory cycling performance owing to its low intrinsic electronic conductivity and dissolution issue. Herein, we design and synthesize a Ag-doped sea-urchin-like MnO₂ material for rechargeable zinc-ion batteries (ZIBs). Doping Ag was found to reduce charge transfer resistance, increase the redox activity, and improve the cycling stability of MnO₂. The unique sea-urchin-like structure maintains rich active sites for charge storage. As a result, the Ag-doped MnO₂-based ZIB presents a high reversible specific capacity to 315 mA h g⁻¹ at 50 mA g⁻¹, excellent rate performance, and a capacity retention of 94.4% when cycling over 500 cycles. An ex situ TEM test demonstrates the low-dissolution property of Ag-doped MnO₂. A flexible quasi-solid-state ZIB is successfully assembled using Ag-doped MnO₂ on graphite paper, which shows a stable specific capacity of 171 mA h g⁻¹ at 1 A g⁻¹ when cycled over 600 cycles. Our investigation demonstrates the significant role played by Ag doping in enhancing the ZIB performance of MnO₂, and gives some insight into developing advanced active materials by heteroatom doping. [ABSTRACT FROM AUTHOR]