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.

Garnet-based all-solid-state Li-metal batteries (ASSLBs) have garnered considerable attention due to their potential for high energy density. However, they remain severely plagued by short-circuit failures caused by Li dendrites penetration. Reducing voids that provide growth sites for Li dendrites within garnet-type solid-state electrolytes (SSEs, Li_6.4La₃Zr_1.4Ta_0.6O₁₂ (LLZTO)) is one promising strategy. Furthermore, the sacrificial powder with identical composition required in conventional sintering processes contains La and necessitates synthesis, resulting in resource wastage. To overcome this limitation, we propose using Li₂O as a sacrificial powder to enhance the densification of garnet-type SSEs, without containing La or requiring synthesis. With an appropriate Li₂O dosage, the garnet-type SSEs can attain a relative density of up to 98.6% and a critical current density of 0.9 mA cm⁻². LiFePO₄/LLZTO/Li cells showcase an average discharge capacity of 145.4 mAh g^–1 at 0.5 C and a capacity retention of 103.4% after 100 cycles at 0.2 C.