Ionic Conductive Polymer Stabilized Cathode–Electrolyte Interface for Quasi-Solid-State Dual-Ion Battery

Quasi-solid-state dual-ion batteries (QSS-DIBs), which represent an emerging part of clean decarbonization technologies, enable sustainable energy storage with metal-free anion-intercalation graphite cathodes. However, the feasibility of QSS-DIBs is constrained by the low areal capacity (<0.2 mA h cm^–2) and rapid performance decay of the graphite cathode. In this report, an anion conductive polymer (ACP) coating layer is introduced to stabilize the cathode–electrolyte interface for durable and high-areal-performance QSS-DIBs. The solvated ACP layer made from metatungstate-doped polyaniline can confine the solvent, which minimizes side reactions on cathodes and promises an exceptional lifespan with 94% capacity retention after 2000 cycles. Most importantly, the ACP accelerates the efficient anion delivery on a high-loading graphite cathode and unlocks a record areal capacity of 1.78 mA h cm^–2 in QSS-DIBs. Finally, the ACP-Gr design promotes both the performance and eco-friendliness of graphite cathodes in QSS-DIBs.