Achieving Ultrahigh Energy Density and Long Durability in a Flexible Rechargeable Quasi-Solid-State Zn-MnO₂ Battery

Advanced flexible batteries with high energy density and long cycle life are an important research target. Herein, the first paradigm of a high-performance and stable flexible rechargeable quasi-solid-state Zn-MnO₂ battery is constructed by engineering MnO₂ electrodes and gel electrolyte. Benefiting from a poly(3,4-ethylenedioxythiophene) (PEDOT) buffer layer and a Mn²⁺ -based neutral electrolyte, the fabricated Zn-MnO₂ @PEDOT battery presents a remarkable capacity of 366.6 mA h g^-1 and good cycling performance (83.7% after 300 cycles) in aqueous electrolyte. More importantly, when using PVA/ZnCl₂ /MnSO₄ gel as electrolyte, the as-fabricated quasi-solid-state Zn-MnO₂ @PEDOT battery remains highly rechargeable, maintaining more than 77.7% of its initial capacity and nearly 100% Coulombic efficiency after 300 cycles. Moreover, this flexible quasi-solid-state Zn-MnO₂ battery achieves an admirable energy density of 504.9 W h kg^-1 (33.95 mW h cm^-3 ), together with a peak power density of 8.6 kW kg^-1 , substantially higher than most recently reported flexible energy-storage devices. With the merits of impressive energy density and durability, this highly flexible rechargeable Zn-MnO₂ battery opens new opportunities for powering portable and wearable electronics.