Efficient Ion Migration and Stable Interface Chemistry of PVDF‐Based Electrolytes for Solid‐State Lithium Metal Batteries

Abstract Poly(vinylidene fluoride) (PVDF)‐based electrolytes with “Li salt‐polymer‐trace residual solvent” configuration have shown great potential in solid‐state lithium metal batteries (SSLMBs). However, the interface failure initiated by the residual solvent and the sluggish Li + migration kinetics caused by the intricacy of the Li + ‐interaction environment severely precludes the large‐scale commercial application of PVDF‐based electrolytes in SSLMBs. Herein, the PVDF‐based electrolytes are fabricated by compositing the PVDF matrix and sand‐ground silicon monoxide (SiO‐a) fillers with silicon monoxide/silicon‐suboxide/silicon‐dioxide (Si/SiO x (0< x <2)/SiO 2 )heterostructure. Results show that SiO‐a not only forcefully anchors the highly reactive N, N ‐dimethylformamide (DMF) molecules, significantly alleviating the side reactions at the electrode‐electrolyte interface, but also the anchored DMF molecule dipole exhibits stronger bond dipole moment (C═ O; 7.1 × 10 −30 C m) than PVDF (C─F; 3.6 × 10 −30 C m), thus weakens the ion‐dipole interaction of Li + ···F, making Li + ‐hopping easily along polymer chains. Consequently, the obtained electrolyte exhibits dramatic electrochemical properties, including a superior ionic conductivity (0.39 mS cm −1 ) and sufficient Li + transference number (0.54). Additionally, the LFP||Li battery presents an outstanding performance at the wide temperature range of −10–60 °C. Even at a high mass loading of ≈11 mg cm −2 , the LFP||Li battery also delivers an impressive specific capacity (156.9 mAh g −1 ) along with average coulombic efficiency (99.8%).