Gel Polymer Electrolyte Enables Low-Temperature and High-Rate Lithium-Ion Batteries via Bionic Interface Design

Traditional ethylene carbonate (EC)-based electrolytes constrain the applications of silicon carbon (Si-C) anodes under fast-charging and low-temperature conditions due to sluggish Li+ migration kinetics and unstable solid electrolyte interphase (SEI). Herein, inspired by the efficient water purification and soil stabilization of aquatic plants, a stable SEI with a 3D desolvation interface is designed with gel polymer electrolyte (GPE), accelerating Li+ desolvation and migration at the interface and within stable SEI. As demonstrated by theoretical simulations and experiment results, the resulting poly(1,3-dioxolane) (PDOL), prepared by in situ ring-opening polymerization of 1,3-dioxolane (DOL), creates a 3D desolvation area, improving the Li+ desolvation at the interface and yielding an amorphous GPE with a high Li+ ionic conductivity (5.73 mS cm-1). Furthermore, more anions participate in the solvated structure, forming an anion-derived stable SEI and improving Li+ transport through SEI. Consequently, the Si-C anode achieves excellent rate performance with GPE at room temperature (RT) and low temperature (-40 degrees C). The pouch full cell coupled with LiFePO4 cathode obtains 97.42 mAh g-1 after 500 cycles at 5 C/5 C. This innovatively designed 3D desolvation interface and SEI represent significant breakthroughs for developing fast-charging and low-temperature batteries. This work develops an inorganic-rich SEI with a 3D desolvation interface in weakly solvating ether-based GPE to enhance fast-charging and low-temperature performance of Si-C anodes. The seaweed-like fibrous structure of PDOL intimately contacts with inorganic SEI and creates a 3D desolvation interface, enhancing Li+ desolvation at this interface. The weakly solvating ability of DOL and PDOL enables FSI- to integrate into the solvated structure of GPE, leading to a Li salts-rich and uniform SEI, which not only improves the stability of SEI but also facilitates Li+ migration through SEI. Consequently, LFP||Si-C pouch full cell retains a discharge capacity of 97.42 mAh g-1 (capacity retention: 81.54% and energy density: 226.62 Wh Kg-1) after 500 cycles at a 5 C/5 C. image