Rational Design of a Cross-Linked Composite Solid Electrolyte for Li-Metal Batteries

The interfacial problem caused by solid–solid contact is an important issue faced by a solid-state electrolyte (SSE). Herein, a cross-linked composite solid electrolyte (CSE) poly(vinylene carbonate) (PVCA)─ethoxylated trimethylolpropane triacrylate (ETPTA)─Li1.5Al0.5Ge1.5(PO4)3 (LAGP) (PEL) is prepared by in situ thermal polymerization. The ionic conductivity and Li+ transference number (tLi+) of PEL increase significantly due to the addition of LAGP, which can reach 1.011 × 10–4 S cm–1 and 0.451 respectively. The electrochemical stable window is also widened to 4.68 V. Benefiting from the integrated interfacial structure, the assembled coin cell shows low interfacial resistance. The all-solid-state NCM622|PEL|Li coin cell exhibits an initial discharge capacity of 169.7 mA h g–1 and 70% capacity retention over 100 cycles at 0.2 C, demonstrating excellent cycling stability.