Solid-State Plastic Crystal-Embedded Brush Polymer Electrolyte for High-Performance and Super Long-Lasting Lithium Metal Batteries at Room Temperature

Lithium metal batteries (LMBs) have long been regarded as promising advanced battery technology. However, due to safety concerns, there is an urgent need for the development of solid-state electrolytes. Solid-state polymer electrolytes (SPEs) offer advantages such as being lightweight, having high elasticity, and having low cost, but they are hampered by issues like low conductivity and narrow potential window. In this study, we present a series of solid-state plastic crystal-embedded brush polymer electrolytes (SPCBPEs) comprising succinonitrile (SN) and a poly(methoxy oligo(ethylene glycol) acrylate) (PMOEGA) brush polymer network. These materials are synthesized via in situ polymerization from monomers with varying numbers of ethylene oxide (EO) segments in the side chains. By carefully adjusting the polymer network structure and SN doping ratio, the optimized SPCBPE-2 exhibits high ionic conductivity (∼7.19 × 10–4 S cm–1), extremely broad electrochemical window (∼5.8 V), and excellent Li+ ions transference number (tLi+ = 0.72). A Li||SPCBPE-2||Li symmetric cell demonstrates exceptional long-term plating/stripping performance at room temperature (26 °C), withstanding 7200 h at 0.2 mA cm–2. Furthermore, Li||SPCBPE-2||LFP LMBs show impressive cycling stability, maintaining 1000 cycles at 1C rate with 80.95% capacity retention. Our SPBCPEs present a straightforward yet powerful design for SPEs and offer significant potential in the field of LMBs.