Self‐Grading and Surface‐Preservation to Enhance the Compaction Density and Structural Stability of Li‐Rich Mn‐Based Cathode

Abstract Li‐rich Mn‐based (LRM) cathode materials are considered promising candidates for next‐generation lithium‐ion batteries due to their high specific capacity and cost‐effectiveness. However, they exhibit deficiencies in volumetric energy density, largely attributable to their lower compaction density, which constrains their application in space‐limited devices such as electric vehicles and portable devices. In this study, (NH₄)₂S₂O₈ surface treatment is proposed to enhance the compaction density and stability performance of LRM cathode materials. This (NH₄)₂S₂O₈ treatment induces the formation of surface Li/O vacancies and spinel structure, leading to an increase in the initial Coulombic efficiency (ICE) from 75.62% to 89.07%, as well as an increase in discharge capacity from 214.2 to 266.01 mAh g⁻¹ compared with the untreated sample. Furthermore, due to the self‐grading generated by the crushing of cathode particles during the treatment process, which results in the enhancement of the compaction density to 3.18 g cm⁻³ and the volumetric energy density of 3145 Wh L⁻¹, significantly surpassing the 2487 Wh L⁻¹ of commercial LRM cathode materials. The present work provides new perspectives for the development of LRM cathode materials with high volumetric energy density.