Fast ion conductor modified double-polymer (PVDF and PEO) matrix electrolyte for solid lithium-ion batteries

Abstract

Organic-inorganic composite solid state electrolytes (SSEs), as one of the most attractive candidates for next generation SSEs, combines the both advantages of flexibility (from organic polymer) and structure rigidity (from robust inorganic constituent). In this work, a high performance three-dimensional (3D) crosslinked electrolyte with polymer poly(vinylidene fluoride) (PVDF) and polyethylene oxide (PEO) matrices is further modified by dispersing submicron fast ion conductor Li1.4Al0.4Ti1.6(PO4)3 (LATP). The optimal 3D composite SSE PVDF@10PEO-5LATP-5LiPF6 (PPLL) shows high ionic conductivities of 5.24 × 10−4 S cm−1 at 25 °C and above 10−3 S cm−1 at 50 °C. Galvanostatic cycling test demonstrates that PPLL contributes to electrochemical performances, with high capacity retention of 93.95% after 500 cycles for LiFePO4 cathode. Further investigations indicate its more benefits including excellent flexibility and superior safety. Intensive explorations imply that the interaction between dual-matrix degrades the respective crystallization through generating weak bonding, and the recombination with LATP further enhances ionic conductivity as well as structural stability of composite electrolyte via strengthening interface reaction, and reducing the organic crystallinity. This composite SSE with high conductivity and stability may be applied in next generation energy storage devices, particularly in all-solid-state secondary batteries.