Improving the stability of ceramic-type lithium tantalum phosphate (LiTa2PO8) solid electrolytes in all-solid-state batteries

Solid-state battery (SSB) systems are among the most promising next-generation batteries for electronics and electric vehicles because of their high volumetric energy density, safety, nonflammability, and chemical stability, compared to lithium-ion batteries using conventional liquid electrolytes. However, SSBs have several limitations, including the reactivity of the electrode materials. Herein, we address these issues by synthesizing lithium tantalum phosphate (LTPO) solid-electrolyte disks through a cold sintering process and assembling them with a lithium manganese iron phosphate (LMFP) electrode into an all-solid-state battery. The SSB fabricated with LTPO/LMFP exhibited a high initial discharge capacity (~130 mAh/g) and capacity retention (70 % after 100 cycles) at room temperature (RT). The LTPO with an amorphous lithium-based composite in the grain boundaries has high ionic conductivity and stability at the interface of the LMFP electrodes. In addition, the LMFP cathodes with an adhesive layer infiltrating the pores of the electrode significantly improved the cyclic performance of the SSB system with an initial capacity of 125 mAh/g and capacity retention of approximately 98 % after 100 cycles at RT. The analysis and future experimental results proved that this novel material and approach can improve the electrochemical performance of rechargeable SSBs and contribute to the development of high-performance energy storage devices for various applications.