Leveraging polymer architecture design with acylamino functionalization for electrolytes to enable highly durable lithium metal batteries

Abstract

Polymer electrolytes are considered one of the most pragmatic choices for achieving lithium metal batteries (LMBs) with enhanced energy density and safety. Nevertheless, unsatisfactory comprehensive performance in terms of inadequate mechanical properties, sluggish Li⁺ transport kinetics, and inferior electrode/electrolyte interfacial stability significantly constrain their practical utility. Herein, a rational molecular-level design is proposed to construct a novel polymer framework for gel polymer electrolytes (GPEs), which is accomplished by incorporating abundant acylamino-sites to establish a subtle hierarchical supramolecular network with permanent chemical crosslinking and reversible hydrogen bonding. The ingenious network combined with soft chain moiety regulation endows GPEs with highly enhanced mechanical strength and adaptable flexibility. Furthermore, the involvement of the unique polymer skeleton creates fast and reversible lanes for lithium-ion transport, with significant contributions from the acylamino sites and the pre-desolvation effect of the whole polymer matrix. Besides, the formation of favorable interphase compositions is conducive to dual-reinforced stable interfaces. Due to the ideal combination of accelerated Li⁺ transport and enhanced interfacial stability, an LFP||Li cell assembled with acylamino-functionalized GPEs exhibits an impressively long lifespan with capacity retention of 96.5% over 850 cycles at 1C, and an LCO||Li cell can maintain a capacity retention of 96.8% after 300 cycles at 1C. This study highlights the significance of bulk electrolytes and interface regulation in tandem and supplies novel insights into rational design for polymer architecture, ramping up the competitiveness of yielded electrolytes for prospective applications in the LMB realm.