Enhanced electrochemical performance in LiNi0.8Co0.15Al0.05O2 cathode material: Resulting from Mn-surface-modification using a facile oxidizing–coating method

• LiNi0.8Co0.15Al0.05O2 was surface-modified by a novel oxidizing–coating method.
• MnO2 dispersed on the surface of Ni0.8Co0.15Al0.05(OH)2 precursor uniformly.
• The modified sample exhibited alleviated capacity fading during cycles.
• The impedance increase of the modified sample during cycles was suppressed.

Mn-surface-modified LiNi0.8Co0.15Al0.05O2 cathode material is successfully prepared from a Mn-containing Ni0.8Co0.15Al0.05(OH)2 precursor, which is obtained through a novel oxidizing–coating method based on the reaction between MnO4− and Ni2+. The structure and morphology of the as-prepared sample are characterized by XRD and SEM respectively; the distribution of Mn is detected by EDS mapping. Compared with pristine sample, the Mn-surface-modified one shows no change in crystal structure or microstructure. By electrochemical characterizations, it is proved that the capacity retention delivered by the Mn-surface-modified sample is remarkably enhanced compared with that of the pristine one. At 2C, the pristine and Mn-surface-modified samples exhibit their respective capacity retentions of 50.9% and 62.9% after 200 cycles at room temperature and the ones of 49.3% and 67.5% after 100 cycles at 55 °C. Furthermore, from the EIS results, the Mn-surface-modified sample is proved to have lower aging rate.