Constructing rapid ionic transfer layer to boost the performance of LiCoO₂ cathode with high mass loading for all-solid-state lithium battery

All-solid-state lithium battery (ASSLB) is a promising candidate in pursuit of high energy density and high security. Among those reported solid electrolytes, sulfide solid electrolyte with the merits of low synthesis temperature, excellent mechanical ductility, good interfacial contact and high ionic conductivity, shows great application potential in ASSLB. However, the instability properties of oxide cathode/sulfide solid electrolyte interface impede the practical application of ASSLB. Therefore, Ti-based materials are used as coating layers on cathode surface to avoid the direct contact between LiCoO₂ cathode and sulfide solid electrolyte. Given the feasibility of this strategy, detrimental side reactions are mitigated and the overall electrochemical performances of ASSLB are significantly improved. More importantly, the ionic conductivity effect of coating material on ASSLB performance is extensively investigated using TiO₂, Li₂TiO₃ and Li₄Ti₅O₁₂ layers with various ionic conductivity (0, 7.75 × 10⁻⁷ S cm⁻¹ and 2.5 × 10⁻⁵ S cm⁻¹). After assembling with LiSiPSCl electrolyte and Li–In anode, Li₄Ti₅O₁₂-coated LiCoO₂ cathode with high mass loading of 36.94 mg cm⁻² remains a discharge capacity of 108 mAh g⁻¹ after 200 cycles at 0.5C. As a sharp contrast, a low capacity retention of 67% is retained for TiO₂-coated LiCoO₂ cathode.