Solid-State\nPlastic Crystal-Embedded Brush Polymer\nElectrolyte for High-Performance and Super Long-Lasting Lithium Metal\nBatteries at Room Temperature

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