Poly(ethylene oxide)/Poly(vinylidene fluoride)/Li6.4La3Zr1.4Ta0.6O12 composite electrolyte with a stable interface for high performance solid state lithium metal batteries

Polymer-ceramic composite electrolyte is an effective solution for developing high-performance and flexible all-solid-state lithium metal battery. However, the key bottleneck of composite electrolyte including low ionic conductivity and high interfacial impedance have impeded their industrialization in solid electrolyte lithium batteries. Here we present a polymer-ceramic hybrid electrolyte (polyethylene oxide (PEO)/polyvinylidene fluoride (PVDF)/Li6.4La3Zr1.4Ta0.6O12 (LLZTO)) is designed and modified by trace amount of liquid electrolyte. The addition of PVDF can not only reduce the crystallinity of PEO polymer, but also intensify the affinity between liquid electrolyte and the composite electrolyte. Furthermore, the interfacial modification can synchronously achieve the intimate connection, low interfacial impedance between the electrodes and solid electrolytes by forming the viscoelastic and stable layer. Due to the artful design, the solid-state battery deliver excellent performance. The Li symmetric cells show excellent interface stability without short circuits for 1000h. The assembled LiFePO4/Li cells exhibit a discharge capacity of 160.1 mA h g−1 after 200 cycles at 0.4C and 143.3 mA h g−1 at 5C. The composite solid electrolyte provides an effective and feasible methods to solve the interfacial issues and develop high performance solid lithium metal batteries.