Lithium-rich layered oxides are promising high-capacity cathodes for lithium-ion batteries, but their commercialization is hindered by severe capacity loss and voltage decay. Herein, we develop a full concentration gradient Li-rich Mn-based layered oxide with gradually decreased Mn and increased Ni concentration from the center to the surface. The gradient material delivers exceptional cycling stability and rate capability, offering a high capacity of 216 mAh g-1 at 1 C and outstanding retention of 91.8% after 200 cycles at 2 C. To elucidate the underlying atomic-level interaction mechanism behind them, in situ magnetism characterization is employed and reveals that the gradient design effectively stabilizes Mn-O interaction and suppresses O-O dimer formation, alleviating irreversible anionic oxygen redox and undesirable structural degradation after long-term cycling. This work affords an effective gradient strategy to regulate the Mn-O interaction, opening up a new perspective for developing Li-rich Mn-based cathode materials.
Qiu et al. (Fri,) studied this question.