Preparation of bi-component ZnO/ZnCo2O4 nanocomposites with improved electrochemical performance as anode materials for lithium-ion batteries

The bi-component ZnO/ZnCo2O4 nanocomposites are prepared via a facile and scalable synthesis method by controlling the ratio of Zn to Co in the synthesis stage. The ZnO/ZnCo2O4 nanocomposites built from the interconnecting porous nanosheets possess loose porous nanostructures with abundant open space and electroactive surface sites. When evaluated as an anode material for lithium ion batteries, the ZnO/ZnCo2O4 nanocomposite electrode exhibits high capacity, good cycling stability (1086 mAh g−1 at 100 mA g−1 after 80 cycles and 847 mAh g−1 at 500 mA g−1 after 200 cycles), and excellent rate capability (∼538 mAh g−1 at 3200 mA g−1), which is superior to most of the previously-reported ZnO-based or ZnCo2O4-based electrode materials. The superior electrochemical performances of the ZnO/ZnCo2O4 nanocomposites are attributed to the loose porous structure, which can buffer the volume expansion and increase the contact area between the electrode and electrolyte. Moreover, a strong synergistic effect between the Zn and Co occurs during the lithiation/delithiation process, where the Zn and Co are acting as mutually beneficial matrix ions to effectively alleviate the large mechanical stress caused by the severe volume change, and thus bring about high and stable capacity.