Electrochemical properties of LATP ceramic electrolyte doped with LiBiO3 sintering additive and its derived sandwich structure composite solid electrolyte

To improve the sinterability, a new LATP-x wt% LiBiO₃ composite solid electrolyte was fabricated by adding LiBiO₃ to a NASICON-type Li_1.5Al_0.5Ti_1.5(PO₄)₃ (LATP) solid electrolyte synthesized by the sol–gel method. The results showed that the liquid phase formed by the LiBiO₃ additive promoted grain growth during the sintering process, which led to structural stability and an increased relative density of LATP. When the LiBiO₃ addition amount was 2 wt%, the relative density was 94%, and the bulk ionic conductivity was 2.91 × 10⁻⁴ S cm⁻¹. In addition, to improve the interfacial instability between the solid electrolyte and lithium metal, we prepared a PPS/LATP-LiBiO₃/PPS composite solid electrolyte with a sandwich structure using a polymer PVDF-HFP-PEO-SN (PPS) cladding method to construct an LFP/SSCEs/Li all-solid-state battery. The electrical property test results showed that the all-solid-state battery still had 92% discharging capacity and nearly 100% coulombic efficiency after 50 cycles at 25 °C and 0.1 C.