Designing Advanced Electrolytes for Lithium Secondary Batteries Based on the Coordination Number Rule
Xuemei Liu, Xiaohui Shen, Laibing Luo, Faping Zhong, Xinping Ai, Hanxi Yang, Yuliang Cao
Abstract
Advanced electrolytes play a key role in the development of next-generation lithium secondary batteries. However, many strong polar solvents, as a major component of the electrolyte, are incompatible with the commercialized graphite anode in Li-ion batteries. In this work, we propose a new concept of the coordination number (CN) rule to tune electrochemical compatibility of electrolytes by regulating the ion–solvent-coordinated (ISC) structure. Based on this rule, we introduced the low-coordination-number solvents (LCNSs) into the high-coordination-number solvent (HCNS) electrolytes to induce anions into the first solvation shell of Li+, forming the anion-induced ISC (AI-ISC) structure. The HCNS-LCNS electrolytes with the AI-ISC structure show enhanced reduction stability, enabling reversible lithiation/delithiation of the graphite anode. Infrared analysis and theoretical calculations confirm the working mechanism of the electrochemical compatibility in the HCNS-LCNS electrolytes based on the CN rule. Therefore, the CN rule provides guidance for the design of highly stable and multifunctional electrolytes to develop next-generation lithium secondary batteries.