Functional Composite Dual‐Phase In Situ Self‐Reconstruction Design for High‐Energy‐Density Li‐Rich Cathodes

Abstract

AbstractThe unique anionic redox mechanism provides, high‐capacity, irreversible oxygen release and voltage/capacity degradation to Li‐rich cathode materials (LRO, Li1.2Mn0.54Co0.13Ni0.13O2). In this study, an integrated stabilized carbon–rock salt/spinel composite heterostructured layers (C@spinel/MO) is constructed by in situ self‐reconstruction, and the generation mechanism of the in situ reconstructed surface is elucidated. The formation of atomic‐level connections between the surface‐protected phase and bulk‐layered phase contributes to electrochemical performance. The best‐performing sample shows a high increase (63%) of capacity retention compared to that of the pristine sample after 100 cycles at 1C, with an 86.7% reduction in surface oxygen release shown by differential electrochemical mass spectrometry. Soft X‐ray results show that Co3+ and Mn4+ are mainly reduce in the carbothermal reduction reaction and participate in the formation of the spinel/MO rock‐salt phase. The results of oxygen release characterized by Differential electrochemical mass spectrometry (DEMS) strongly prove the effectiveness of surface reconstruction.