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 LiNi_0.8Co_0.1Mn_0.1O₂ 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||LiNi_0.8Co_0.1Mn_0.1O₂ cells deliver Coulombic efficiency above 99 % at both 25 and −30 °C.