Catholyte-free composite cathodes to improve the energy density of low-cost LiMn₂O₄-based all-solid-state lithium batteries

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.