A Solid–Liquid Hybrid Electrolyte With Weak‐Solvated Solvent to Reduce Li⁺ Transfer Barrier at Electrode and Solid Electrolyte Interphase

The interface problem caused by the contact between electrode and solid electrolyte (SE) is the main factor hindering the development of solid‐state batteries. And adding liquid electrolyte (LE) at the interface to form a solid–liquid hybrid electrolyte is the common strategy. The ion transport kinetics at the SE/LE interface include an active role for the (de)solvation of ions, and the energy barrier for Li + transport between the liquid and solid phases is closely related to the solvation capacity of the solvent. Herein, the influence of the solvation structure of the electrolyte itself on the interface is investigated. Compared to dimethyl carbonate (DMC), the lower Li + binding energy of tetrahydrofuran (THF) is more easily desolvated at the solid–liquid interface, allowing the formation of abundant aggregates and the generation of inorganic‐rich interfacial phases, leading to interfacial compatibility. Using the combination of polyvinylidene fluoride (PVDF)‐based SPE and THF‐based LE, the cycle performance and rate performance of LiFePO 4 (LFP) |SPE|Li batteries are improved. The Li/Li symmetric cell can achieve stable cycling over 1000 h at a current density of 0.05 mA cm −2 , and LFP/Li half‐cell retains 93% of its initial capacity after 100 cycles at 0.5 C. This study can provide inspiration for the design of solid–LE interface.