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 x 10-7 S cm- 1 and 2.5 x 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.

Automated summary

All-solid-state lithium batteries offer high energy density and security. By using coating materials to create a barrier between the oxide cathode and sulfide solid electrolyte, the overall electrochemical performance of the battery is significantly improved.