Ultra-thin Al2O3 coating on the acid-treated 0.3Li2MnO3⋅0.7LiMn0.60Ni0.25Co0.15O2 electrode for Li-ion batteries

•0.3Li2MnO3⋅0.7LiMn0.60Ni0.25Co0.15O2 composites were preconditioned by HNO3.•The alumina thin film was directly coated on the electrode by an atomic layer deposition.•The acid-treated samples showed significantly higher discharge capacity.•The alumina-coated electrode showed the improved capacity retention ratio.

The Li and Mn-rich layered composites represented by Li2MnO3–LiMO2 has been attracting great interests owing to its exceptional high capacity (⩾250 mA h g−1) and enhanced structural stability. In order to improve the initial coulombic efficiency and cyclability of the composites, the material has been activated by an acid-treatment and coated with an Al2O3 using an atomic layer deposition (ALD). The acid-treated electrode showed a higher discharge capacity than the as-prepared electrode. The alumina-coated electrode provided an improved specific capacity of the electrode but also cycling stability, when compared with the bare electrode. The electrode coated with the alumina could lead to a decrease in undesirable reactions, thereby acting as a stable protecting layer that could quickly transport Li+ ions during charge and discharge process.