Succinonitrile coordination-induced in situ polymerization-based composite solid electrolytes for solid-state batteries

As a next-generation battery material, solid electrolytes (SEs) are essential to realize high stability and high energy density applications. However, SEs have poor interfacial contact between electrodes. In this study, a novel SE is fabricated via the in situ polymerization of poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) and a composite solid electrolyte (CSE) based on Ga and Rb-doped Li 7 La 3 Zr 2 O 12 (LLZO), using precursor solutions of polyethylene glycol methyl ether acrylate (PEGMEA) and succinonitrile (SN). This well-designed electrolyte exhibits high ionic conductivity (1.3 × 10 −4 S cm −1 ) at 30 °C, wide electrochemical window of 4.9 V (vs. Li/Li + ), and high Li-ion transference number of 0.84. In addition, it can maintain a stable interface with Li metal, which shows high long-term cycling stability in LFP- and NCM-based cells. Cells manufactured as pouch cells under various abuse conditions show excellent durability, demonstrating the potential of the proposed solid electrolyte for next-generation secondary batteries. • CSEs were prepared by in situ polymerization using PEGMEA, SN, and LLZO. • P(PEGMEA)-SN30 shows 1.3 × 10 −4 S/cm at 30 °C and t Li + of 0.84. • Anchored SN improves Li interface and thermal stability up to 200 °C. • Pouch cells show stable cycling and tolerance to abuse conditions.