Catholyte-free composite cathodes to improve the energy density of low-cost LiMn 2 O 4 -based all-solid-state lithium batteries

Abstract The cost-effective manganese-based spinel oxide LiMn2O4 (LMO) is a promising cathode material for large-scale applications in all-solid-state lithium batteries (ASSLBs). However, the gravimetric energy density of all-solid-state lithium pouch batteries (ASSLPBs) with conventional catholyte-based composite cathodes containing LMO is only about 256.8 Wh kg–1, far below the target value of 500 Wh kg–1, and the Jahn-Teller distortion leads to poor cycling stability. To address this issue, the study proposes replacing the inert catholyte with an active halide cathode Li3TiCl6 (LTC) and combining it with the low-cost LMO cathode to form a design of catholyte-free composite cathodes. During deep charge and discharge cycles, the Ti in LTC inserts into the lattice of LMO, which both improves the discharge specific capacity of the catholyte-free composite cathode to 316.3 mAh g–1 and extends the cycling life by reducing the Jahn-Teller distortion. As a result, the gravimetric energy density of the ASSLPB with the catholyte-free composite cathode reaches 588.8 Wh kg–1, which is 2.3 times higher than that of conventional catholyte-based composite cathodes. Therefore, the design of the catholyte-free composite cathode effectively solves the issues of insufficient energy density and short cycling life of low-cost LMO cathodes in large-scale applications.