Sulfide or halide solid electrolyte: Which is more suitable for co-free Li-rich Mn-based oxide cathode all-solid-state batteries?

LRNM/LIC delivers 253.4 mAh g⁻ 1 at 0.1 C, outperforming LRNM/LSPSC (168.5 mAh g⁻ 1 ). • LIC forms stable In 2 O 3 passivation layer, but LSPSC has irreversible side reactions. • VGCF enables LRNM/LIC/VGCF to retain 98.72% capacity after 100 cycles at 0.2 C. Cobalt-free lithium-rich manganese-based oxides have emerged as promising cathode materials for all-solid-state lithium batteries (ASSLBs) owing to their high energy density and cost efficiency. This study systematically evaluates the interfacial compatibility between the 0.3Li 2 MnO 2 ·0.7LiNi 0.5 Mn 0.5 O 2 (LRNM) cathode and two representative solid electrolytes—namely, the sulfide electrolyte Li 9.54 Si 1.74 P 1.44 S 11.7 Cl 0.3 (LSPSC) and the halide electrolyte Li 3 InCl 6 (LIC). The LRNM/LIC cathode achieves a high specific discharge capacity of 253.4 mAh g −1 at 0.1 C, which considerably exceeds that of the LRNM/LSPSC cathode (168.5 mAh g −1 ). Moreover, the LRNM/LIC cathode retains 87.32% of its initial capacity after 100 cycles at 0.5 C, indicating excellent cycling stability. The main reason for this improvement is that LSPSC undergoes irreversible side reactions at the interface with LRNM, generating substances such as SO 4 2- , SO 3 2- , and polysulfides. By contrast, LIC reacts with LRNM to form a stable interface layer (In 2 O 3 passivation layer), which inhibits continuous interfacial side reactions and substantially enhances interface stability. Furthermore, the influence of different conductive agents (vapor-grown carbon fiber (VGCF), carbon nanotubes, and acetylene black) on the conductivity and interfacial stability of LRNM/LIC is explored. Results indicate that the cycling stability of the LRNM/LIC/VGCF cathode is enhanced, achieving a capacity retention rate of 98.72% at 0.2 C after 100 cycles because VGCF forms a continuous three-dimensional conductive network. This study provides valuable insights for the development of low-cost LRNM-based ASSLBs with high energy density. Download: Download high-res image (227KB) Download: Download full-size image