Superior High-Rate Ni-Rich Lithium Batteries Based on Fast Ion-Desolvation and Stable Solid-Electrolyte Interphase.

Abstract

The fast charging-discharging performance of power batteries has very practical significance. In terms of electrochemistry, this requires fast and stable kinetics for electrochemical reaction processes. Despite the great complexity of kinetics, it is clear that lithium-ion desolvation and a subsequent step of crossing through cathode-electrolyte interphase (CEI) are crucial to high-rate performance, in which the two key steps depend heavily on the working electrolyte formula. In this work, a customized electrolyte is developed to coordinate ion desolvation and interphase formation by introducing vinylene carbonate (VC), triphenylboroxin (TPBX), and fluoroethylene carbonate (FEC) but excluding ethylene carbonate (EC). Serving Ni-rich cathodes, the customized electrolyte generates a double-layered CEI, LiF-dominated inorganics inner layer, and ROCOOLi-dominated organics outer layer, which is not only stable and very efficient for lithium ion transport. Meanwhile, a PF 6 - ${\mathrm{PF}}_6^ - $ -dominated solvation structure is induced and effectively decreases the desolvation energy to 29.72 kJ mol-1, supporting fast lithium ion transport in the cathode interfacial processes. Consequently, the Ni-rich lithium-ion battery achieves a stable long cycle at a superior high rate of 10 C.