Frontier Orbital Energy-Customized Ionomer-Based Polymer Electrolyte for High-Voltage Lithium Metal Batteries
Xintong Li, Xiaoqi Han, Huanrui Zhang, Rongxiang Hu, Xiaofan Du, Peng Wang, Botao Zhang, Guanglei Cui
Abstract
The development of gel polymer electrolytes (GPEs) is considered to be an effective strategy to drive practical applications of high-voltage lithium metal batteries (HLMBs). However, rare GPEs that can satisfy the demands of HLMBs have been developed because of the limited compatibility with lithium anodes and high-voltage cathodes simultaneously. Herein, a novel strategy for constructing polymer matrixes with a customized frontier orbital energy for GPEs is proposed. The as-investigated polymer matrix (P(CUMA-NPF6))-based GPE (P(CUMA-NPF6)-GPE) obtained via in situ random polymerization delivers a wide voltage window (0–5.6 V vs Li+/Li), large lithium-ion transference number (tLi+, 0.61), and superior electrode/electrolyte interface compatibility. It is to be noted that such a tLi+ of P(CUMA-NPF6)-GPE, which is one of the largest tLi+ among high-voltage GPEs in a fair comparison, results from the high dissociation of lithium salts and effective anion immobilization abilities of P(CUMA-NPF6). Ultimately, the as-assembled HLMB delivers more enhanced cycle performance than its counterpart of commercial liquid electrolytes. It is also demonstrated that P(CUMA-NPF6) can scavenge the active PF5 intermediate generated in the electrolyte at the anode side, thus suppressing the PF5-mediated decomposition reaction of carbonates. This work will enlighten the rational structure design of GPEs for HLMBs.