Surface Reconstruction\nof High-Voltage LiNi<sub>0.5</sub>Mn<sub>1.5</sub>O<sub>4</sub> Cathode\nvia the Sculpture Method toward\nEnhanced Stability

High-voltage LiNi<sub>0.5</sub>Mn<sub>1.5</sub>O<sub>4</sub> (LNMO)\ncathodes suffer from severe capacity degradation during long-term\ncycling due the manganese dissolution and their high operating voltage\n(∼4.95 V), which pose serious challenges at the surface or\ninterface. Moreover, both traditional ion-doping and passivation layer\ncoating are difficult to apply consistently to LNMO cathode because\nof their complicated procedures, especially in large-scale production.\nTo address these issues, a strategy employing HNO<sub>3</sub>/H<sub>2</sub>O<sub>2</sub> leaching in synergy with a sintering process\nat a mid-temperature of 700 °C was used to achieve selective\nsurface reconstruction. An optimal ratio of reactants was applied\nto balance the capacity and the cyclic stability of the LNMO cathode.\nThe optimized valence composition of Mn on the material surface mitigates\nthe occurrence of Jahn–Teller distortion, accompanied by a\nreasonable ratio of ordered and disordered phases and the concentration\nof oxygen vacancies after sintering, which improves the interface\nbehavior between the electrode and electrolyte. This method delivers\na high reversible capacity of 116.5 mAh g<sup>–1</sup> after\n200 cycles at 0.5 C (1 C = 147 mAh g<sup>–1</sup>) with a capacity\nretention of 91.30% and 110 mAh g<sup>–1</sup> with a remarkably\nhigh capacity retention of 86.85% after 500 cycles at 2 C. This balanced\napproach, utilizing the protective effects of oxidation (O<sub>2</sub><sup>2–</sup>) and the erosive action of acid (H<sup>+</sup>), is proposed to achieve regional surface reconstruction of advanced\nLNMO cathode. This opens up a strategy for improving oxide-based cathode\nmaterials with low cost and mass production capability, especially\nfavoring high consistency.