Frontier Orbital Energy-Customized Ionomer-Based Polymer Electrolyte for High-Voltage Lithium Metal Batteries

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.