Well‐Dispersed Polydopamine In Situ Coated Lithium Montmorillonite Nanofillers Composite Polyethylene Oxide‐Based Solid Electrolyte for All‐Solid‐State Lithium Batteries

In lithium batteries, composite solid electrolytes gain their reputation owing to their great safety, excellent mechanical properties, and remarkably improved electrochemical performance. Herein, composite polyethylene oxide (PEO)‐based solid electrolytes with well‐dispersed in situ polydopamine‐coated lithium montmorillonite (PDA@LiMMT) nanofillers are successfully fabricated. The involvement of PDA@LiMMT retards significantly the crystallization of PEO, addressing a manifest enhancement in the ionic conductivity of the modified composite solid electrolyte. A conducive ionic conductivity value of 3.06 × 10 −4 S cm −1 at 60 °C is reached, while the electrochemical window widens to 4.7 V. The assembled Li/solid polymer electrolytes/LiFePO 4 battery exhibits a 158.2 mA h g −1 high discharge specific capacity at a current density of 0.5C; besides, the capacity retention rate keeps 86% after 200 cycles. The enhancement of the cycle stability of the solid‐state batteries highlights the excellent interfacial stability between the modified solid electrolytes and the lithium electrode, which originates from lithiophilicity of PDA.