CuO-ZnO submicroflakes with nanolayered Al2O3 coatings as high performance anode materials in lithium-ion batteries

Abstract

Transition metal oxides are said to have the ability to enhance the gravimetric capacity of lithium-ion batteries by two or three times that of current state-of-the-art graphite anodes. Recent reports have demonstrated that the combined utilization of structural architecture and surface modification is an attractive strategy to improve lithium storage capability. In this study, novel CuO-ZnO@Al2O3 submicroflakes were prepared by magnetron sputtering deposition of Cu-Zn alloy films on a removable sacrificial substrate, followed by a facile thermal oxidation treatment and Al2O3 coating procedure by particle atomic layer deposition. They combine the advantages of CuO-ZnO submicroflakes, such as high lithium storage capability and fast lithium ion transportation, and Al2O3 nano-coating with effective protection of the electrode interface during cycling. When utilized as anode materials for LIBs, the CuO-ZnO@Al2O3 submicroflakes exhibit superior specific capacity, enhanced cycling stability, and outstanding rate capability compared with pristine CuO-ZnO submicroflakes, commercial CuO and ZnO powders. The CuO-ZnO@Al2O3 submicroflakes electrodes deliver a high reversible capacity of 814 mAh g−1 at a current density of 50 mA g−1, and still maintain a moderate capacity of 447 mAh g−1 at a high current density of 1000 mA g−1. Pairing with a commercial LiFePO4 cathode, full cell shows high capacity retention and stable cycling performance, suggesting the feasibility of the CuO-ZnO@Al2O3 submicroflakes in practical energy storage applications. In addition, our findings also provide a clear proof-of-concept of the surface coating technique, which might be applied widely to other materials and devices where nano-coating produces desirable properties.