Fabrication And Application Of Zinc Oxide (Sulfide)/Carbon Composite Anode Materials For Lithium-Ion Battery

Metal oxide (sulfur) compounds will be the ideal candidates for anode materials of the next generation lithium-ion battery because its theoretical capacity is extremely higher than traditional graphite material. However, this type of material has some drawbacks i.e. low efficiency at first cycle, poor electronic conductivity, low reactivity and volume changes during discharge-charge cycling etc. which restrict its development and applications. In the thesis, the unique structures of Zinc Oxide (Sulfide)/Carbon composites anode materials have been fabricated by confined method. The morphology and electrochemical performances of the materials have been studied. Besides, the thermal decomposition process of precursor has been expounded systematically and the relationships between material structure and performance have been explained deeply. Specific studies are as follows:1. A heterogeneous layer-structured material of layer-by-layer ZnO/Carbon was synthesized by a confined method, in which the main steps are as follows:the organic molecules as carbon source were first embedded into the galleries of zinc hydroxide hosts by intercalation method, and then it is realized to limit the in situ growth of carbon nanomaterials so as to generate the ZnO/Carbon nanohybrids with layered structure. The structure characteristic of ZnO/Carbon is that the ZnO layers and Carbon layers are arranged alternately to form a heterogeneous layered structure. When used as an anode material for Lithium-ion battery, the ZnO/Carbon nanohybrids exhibits an initial discharge and reversible charge capacities of 1289 mAh·g-1 and 766 mAh·g-1, respectively. Besides, the ZnO/Carbon nanohybrids retains a remarkable reversible capacity of 970 mAh·g-1 at the end of 100 cycles with a current density of 0.2 A·g-1. Even at very high rates, such as 3 A·g-1 and 8 A·g-1 current density, the electrode retains a specific capacity of-408 mAh·g-1 and ～200 mAh·g-1, respectively.2. A hierarchical structured material of flower-like ZnS-Al2O3/N-C was fabricated by a confined method, in which the main steps are as follows:the organic anion molecules as carbon source were first embedded into the galleries of ZnⅡAlⅢ layered double hydroxide hosts by intercalation method, and then it is realized to limit the in situ growth of carbon nanomaterials so as to generate the nanohybrids with hierarchical structure. The structure characteristic of ZnS-Al2O3/N-C is that the active component of ZnS was uniformly loaded on the carbon plates the average size is 2-3 nm to form a hierarchical flower-like structure. When used as an anode material for Lithium-ion battery, the ZnS-Al2O3/N-C nanohybrids exhibits an initial discharge and reversible charge capacities of 1142.4 mAh·g-1 and 663.7 mAh·g-1, respectively. Besides, the ZnS-Al2O3/N-C nanohybrids retains a remarkable reversible capacity of 839 mAh·g-1 at the end of 200 cycles with a current density of 0.2 A·g-1. Even at very high rates, such as 4 A·g-1 and 6 A·g-1 current density, the electrode retains a specific capacity of ～294 mAh·g-1 and ～212 mAh·g-1, respectively.