Stabilization the Electrode/Electrolyte Interphase by Reconstructing the Solvation Structure of Eutectic‐Based Polymer Electrolyte

Abstract The development of Quasi solid polymer electrolyte (QSPE) is recognized as a promising approach to achieving lithium (Li) batteries simultaneously with high energy‐density and high safety. However, the electrolytes capable of forming a stable solid electrolyte interphase/cathode electrolyte interphase (SEI/CEI) layer remain a major challenge. Herein, a novel eutectic‐based QSPE consisting of succinonitrile, Li bis(trifluoromethanesulfonyl)imide, and a rationally designed polymer network is developed. By adjusting the eutectic components in QSPEs, the Li + solvation structures can be well reconstructed, which induces the formation of an inorganic‐rich SEI/CEI layer simultaneously. As a result, the assembled Li|QSPE‐3|LiFePO 4 (LFP) cell exhibits a high‐capacity retention of 99% over 700 cycles at 0.5C, and a cell with a high mass loading LFP cathode (≈3.53 mAh cm −2 ) can stably cycle for 150 cycles at 25 °C (capacity retention 88.3%). It is found that the restricted solvation structure can induce the formation of LiF and Li 3 N‐rich SEI/CEI on the electrode surface, thus inhibiting Li dendrite growth. This study provides a new strategy for the design of QSPEs with a stabilized electrode/electrolyte interface protection layer for Li metal batteries.