Electrostatic Force‐Tailored PEO‐Based Solid Electrolyte with Fast Li+ Transport for Ultra‐Robust Lithium Metal Batteries

Abstract Polyethylene oxide (PEO)‐based solid polymer electrolytes exhibit promising commercial prospects due to their superior processability and scalability. However, limited ion transport and unstable electrode/electrolyte interface restrict their practical application. Herein, the paraelectric strontium titanate (STO) is introduced into PEO‐based electrolytes to solve those problems. The electrostatic force originating from polarized STO weakens the coordination between EO and Li + and releases more free Li + , thus promoting ion transport inside the electrolyte. Numerous STOs form a new reverse electric field that inhibits lithium dendrites' vertical growth at the anode interface. Polarized STO triggers the generation of LiF, Li 2 O, and Li 3 N‐riched solid electrolyte interphase (SEI), contributing to interfacial stability and Li + mobility. Consequently, polarized STO‐modified PEO‐based solid electrolyte has an outstanding ion conductivity of 0.61 mS cm −1 with a superior lithium stability of 5.29 V. Li/Li symmetric battery with STO‐modified electrolyte undergoes >1200 h at 0.2 mA cm −2 . A large capacity retention of 85.3% after 850 cycles at 1 C is achieved for LFP/Li battery and be cycled 600 times even against a high‐loading cathode (LFP:6 mg cm −2 ). This study provides a novel strategy to prepare composite‐modified solid‐state electrolytes that can be utilized in lithium metal batteries.