Integrated Design for in Situ Ultra-Stable Gel Polymer Electrolyte Network Enables Long-Cycling and High-Voltage Lithium Metal Batteries.

In situ polymerized electrolytes are considered as promising candidates for next-generation lithium metal batteries (LMBs) due to their conformal interface contact and compatibility with existing battery manufacturing processes. However, their application in LMBs is hindered by dendrite growth, a narrow electrochemical stability window, and low thermal stability. By constructing a cross-linked network via in situ copolymerization of 1,3-dioxolane (DOL) and S,S,S-triglycidyl isocyanurate (S,S,S-TGIC), the resulting TPDOL-based gel polymer electrolyte (GPE) effectively suppresses interfacial side reactions and significantly enhances oxidation stability. In addition, the electronegative nitrogen atoms on S,S,S-TGIC weaken ether-Li+ coordination, lowering the desolvation energy barrier and promoting uniform lithium deposition. Consequently, the resulting GPE delivers a high ionic conductivity of 1.66 × 10-3 S cm-1 and a wide electrochemical stability window of 5.7 V. The Li||Li symmetric cell achieves ultra-long cycling stability exceeding 2200 h at 1 mA cm-2. When coupled with high-voltage LiNi0.8Co0 .1Mn0.1O2 (NCM811) cathodes, the full cell retains 86.7% capacity after 200 cycles at 1 C. Even with a high NCM811 loading of 7.1 mg cm-2, the cell achieves a stable initial discharge capacity of 155.4 mAh g-1. This polymer design strategy demonstrates significant promise for the development of high-energy-density LMBs.