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

Sun, Shuo; Zhao, Chen-Zi; Yuan, Hong; Fu, Zhong-Heng; Chen, Xiang; Lu, Yang; Li, Yun-Fan; Hu, Jiang-Kui et al. · Sci Adv · 2022

basic_science · Level V

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Abstract

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 (~248 mAh g<sup>-1</sup>, 1.1 mAh cm<sup>-2</sup>; ~225 mAh g<sup>-1</sup>, 2.9 mAh cm<sup>-2</sup>) 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.