Solvation‐Tailored PVDF‐Based Solid‐State Electrolyte for High‐Voltage Lithium Metal Batteries

Poly(vinylidene fluoride) (PVDF)‐based polymer electro‐lytes are attracting increasing attention for high‐voltage solid‐state lithium metal batteries because of their high room temperature ionic conductivity, adequate mechanical strength and good thermal stability. However, the presence of highly reactive residual solvents, such as N, N‐dimethylformamide (DMF), severely jeopardizes the long‐term cycling stability. Herein, we propose a solvation‐tailoring strategy to confine residual solvent molecules by introducing low‐cost 3 Å zeolite molecular sieves as fillers. The strong interaction between DMF and the molecular sieve weakens the ability of DMF to participate in the solvation of Li+, leading to more anions being involved in solvation. Benefiting from the tailored anion‐rich coordination environment, the interfacial side reactions with the lithium anode and high‐voltage NCM811 cathode are effectively suppressed. As a result, the solid‐state Li||Li symmetrical cells demonstrates ultra‐stable cycling over 5100 h at 0.1 mA cm−2, and the Li||NCM811 full cells achieve excellent cycling stability for more than 1130 and 250 cycles under the charging cut‐off voltages of 4.3 V and 4.5 V, respectively. Our work is an innovative exploration to address the negative effects of residual DMF in PVDF‐based solid‐state electrolytes and highlights the importance of modulating the solvation structures in solid‐state polymer electrolytes. Residual DMF solvents in PVDF‐based solid‐state electrolytes suffered from inevitably serious side reactions with high‐voltage NCM811 cathode and lithium metal anode which restrict the cycling performance of solid‐state Li||NCM811 cells. We proposed a novel strategy of anchoring DMF solvents by incorporating low‐cost 3 Å zeolite molecular sieves as fillers to modulate the solvation structures in PVDF‐based solid state electrolyte. Inorganic‐rich SEI and CEI derived from the tailored anion‐rich solvated structure guarantee long‐term cycling stability of the solid‐state Li||NCM811 cell at high cut‐off voltages of 4.3 V and 4.5 V.