High Li<sup>+</sup> Transference Number Electrolyte Enabled by Fluoride Acceptor for Low-Temperature Li-Ion Batteries
Md. Anwar Hossain, Dezhen Wu, Qijia Zhu, Qian Liu, Jingtian Yang, Jiayi Xu, Cong Liu, Seungyeop Kang, Zhenzhen Yang, Seoung‐Bum Son, Dong‐Joo Yoo, Zhengcheng Zhang
Abstract
To enable wide-temperature operation of lithium-ion batteries (LIBs), new electrolyte formulations have been developed to enhance the performance, particularly at low temperatures. A key challenge lies in achieving both high ionic conductivity and a high lithium-ion transference number due to their inherent trade-off. In this study, we designed an electrolyte system comprising tris(pentafluorophenyl)borane (TPFPB), a fluoride acceptor, and LiF salt in ethylene carbonate (EC)-free solvents. TPFPB, with its electron-deficient boron center, facilitates fluoride transfer reactions that promote the dissociation of otherwise insoluble LiF. When methyl acetate (MA) was used as the solvent, the electrolyte exhibited a high transference number ( t Li + = 0.85) and ionic conductivity (σ = 5.0 × 10 –3 S cm –1 ). The optimized electrolyte demonstrated excellent performance at −20 °C, with no evidence of lithium plating. This work presents a new strategy for electrolyte design by leveraging cation desolvation to achieve high-performance LIBs for low-temperature and high-power applications.