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 Li1.5Al0.5Ti1.5(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.