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

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.