A Li-rich layered oxide cathode with negligible voltage decay

With high capacity at low cost, Li- and Mn-rich (LMR) layered oxides are a promising class of cathodes for next-generation Li-ion batteries. However, substantial voltage decay during cycling, due to the unstable Li₂MnO₃ honeycomb structure, is still an obstacle to their practical deployment. Here we report a Co-free LMR Li-ion battery cathode with negligible voltage decay. The material has a composite structure consisting of layered LiTMO₂ and various stacked Li₂MnO₃ components, where transition metal (TM) ions that reside in the Li layers of Li₂MnO₃ form caps to strengthen the stability of the honeycomb structure. This capped-honeycomb structure is persistent after high-voltage cycling and prevents TM migration and oxygen loss as shown by experimental and computational results. This work demonstrates that the long-standing voltage decay problem in LMRs can be effectively mitigated by internally pinning the honeycomb structure, which opens an avenue to developing next-generation high-energy cathode materials. © 2023, The Author(s), under exclusive licence to Springer Nature Limited.