Eliminating interfacial O-involving degradation in Li-rich Mn-based cathodes for all-solid-state lithium batteries

In the pursuit of energy-dense all-solid-state lithium batteries (ASSBs), Li-rich Mn-based oxide (LRMO) cathodes provide an exciting path forward with unexpectedly high capacity, low cost, and excellent processibility. However, the cause for LRMO| solid electrolyte interfacial degradation remains a mystery, hindering the application of LRMO-based ASSBs. Here, we first reveal that the surface oxygen instability of LRMO is the driving force for interfacial degradation, which severely blocks the interfacial Li-ion transport and triggers fast battery failure. By replacing the charge compensation of surface oxygen with sulfite, the overoxidation and interfacial degradation can be effectively prevented, therefore achieving a high specific capacity (similar to 248 mAh g(-1), 1.1 mAh cm(-2); similar to 225 mAh g(-1), 2.9 mAh cm(-2)) and excellent long-term cycling stability of >300 cycles with 81.2% capacity retention at room temperature. These findings emphasize the importance of irreversible anion reactions in interfacial failure and provide fresh insights into constructing stable interfaces in LRMO-based ASSBs.

Automated summary

The surface oxygen instability of Li-rich Mn-based oxide (LRMO) cathodes is identified as the cause for interfacial degradation in all-solid-state lithium batteries (ASSBs). By replacing surface oxygen with sulfite, overoxidation and interfacial degradation can be effectively prevented, leading to high capacity and cycling stability.