Modulating Interfacial Solvation via Ion Dipole Interactions for Low-Temperature and High-Voltage Lithium Batteries

Abstract

Extending the stability of ether solvents is pivotal for developing low-temperature and high-voltage lithium batteries. Herein, we elucidate the oxidation behavior of tetrahydrofuran with ternary BF4-, PF6- and difluoro(oxalato)borate anions and the evolution of interfacial solvation environment. Combined in-situ analyses and computations illustrate that the ion dipole interactions and the subsequent formation of ether-Li+-anion complexes in electrolyte rearrange the oxidation order of solvated species, which enhances the electrochemical stability of ether solvent. Furthermore, preferential absorption of anions on the surface of high-voltage cathode favors the formation of a solvent-deficient electric double layer and an anti-oxidation cathode electrolyte interphase, inhibiting the decomposition of tetrahydrofuran. Remarkably, the formulated electrolyte based on ternary anion and tetrahydrofuran solvent endows the LiNi0.8Co0.1Mn0.1O2 cathode with considerable rate capability of 5.0 C and high capacity retention of 93.12% after 200 cycles. At a charging voltage of 4.5 V, the Li||LiNi0.8Co0.1Mn0.1O2 cells deliver Coulombic efficiency above 99% at both 25 and -30 °C.