Competitive Coordination and Confinement in Rigid‐Flexible Networks for High‐Rate and Ultra‐Stable Quasi‐Solid‐State Batteries

ABSTRACT High‑voltage lithium‑metal batteries are a key route to ultra‑high energy density, yet their practical application is critically hindered by the lack of electrolytes capable of simultaneously stabilizing both the lithium metal anode and the high‐voltage cathode. Herein, a quasi‑solid electrolyte with balanced rigidity and flexibility is designed via thermally initiated polymerization. Dipentaerythritol hexaacrylate forms a highly cross‑linked rigid framework to suppress dendrite growth, while methyl methacrylate builds continuous flexible chains that provide fast ion‑transport pathways. Through competing coordination interactions and nanoscale confinement, the polymer network reshapes Li + solvation and reduces free solvent molecules, extending the electrolyte's oxidative stability beyond 4.8 V (vs. Li/Li + ). Based on the above advantages, the Li||Li symmetric cell achieves a stable cycle life for over 4 000 h at 0.5 mA cm −2 . Li full cell demonstrates exceptional high rate capability and ultra‐stable cycling performance, maintaining 88.8% of its initial capacity after 2 200 cycles at 5C rates. Furthermore, cells with this electrolyte show stable cycling performance up to 4.5 V and achieve a pouch‑cell energy density of 512.5 Wh kg −1 . This molecular design concurrently optimizes mechanical strength, ionic conductivity, and interfacial stability, offering a new framework for high‑performance high‑voltage lithium‑metal batteries.