Improving cathode/Li_6.4La₃Zr_1.4Ta_0.6O₁₂ electrolyte interface with a hybrid PVDF-HFP-based buffer layer for solid lithium battery

Solid-state lithium battery is considered as a promising solution to improve safety performance. However, huge interfacial resistance and polarization between cathode and solid electrolyte are still big challenges for further application. In this study, an improved cathode/Li_6.4La₃Zr_1.4Ta_0.6O₁₂ garnet electrolyte interface with low resistance and reduced polarization is successfully constructed by introduced a Li_6.4La₃Zr_1.4Ta_0.6O₁₂-C added hybrid PVDF-HFP-based buffer layer. The hybrid buffer layer provides ionic and electronic transport pathways simultaneously at the interface. With the improved interface, the LiFePO₄ cathode in the solid-state battery using LLZTO electrolyte displays an increased Li⁺ diffusion coefficient of 3.42 × 10⁻¹² cm² s⁻¹ and low charge transfer resistance of 345.2 Ω at 1st cycle. The LFP solid-state battery reaches an initial capacity of 152.2 mA h g⁻¹ and, in particular, displays an outstanding cycle performance with a retention of 84.6% over 200 cycles at 0.5 C and an average columbic efficiency of 99.5%.