| Lithium-ion batteries (LIBs) with carbonaceous materials serving as anodes were commercialized in 1990. After nearly 25 years, LIBs have been considered as the most important rechargeable batteries because of their outstanding features such as high energy density, small self-discharge, and minimal memory effect. However, the applications of carbonaceous anode materials are limited by their low reversible lithium intercalation capacity and mutual solvent intercalation. Over the past decades, other materials such as metals, non-metals, and metal oxides, etc. have been studied as alternatives of carbonaceous anode. Among these new materials, Sn-based materials and some transition metal oxides have attracted increasing attention because of their distinct lithium reaction mechanisms and electrochemical features. But they also have some shortcomings such as severe pulverization during charge and discharge process and poor electronic conductivity of metal oxides. To overcome these shortcomings, many approaches have been explored. The most common ways are reducing the particle size to nanoscales, using porous structure, alloying with other metals and adding carbonaceous material. The researches of this dissertation focus on Sn-base material and transition metal oxide. By combining porous structure, alloying with other metal and adding of MWCNT, new methods to improve the performance of these materials are established.Chapter one summarizes the principle and application of lithium ion battery and problems need to resolve. The types of main studied anode materials and their research progresses are also reviewed. The anode materials were divided into carbon materials, metal and alloy materials, metal oxide materials, and non-metal materials. Both the advantages and disadvantages of these materials are discussed with the methods to improve their electrochemical performance summarized as well. The principle and application of porous structure and carbon doping was emphasized.In the second chapter, the instruments and reagents used in the experiments were introduced. The preparation and characterization methodes weredescribe.Chapter three focuses on Sn-Sb-based ternary alloy materials Sn-Sb-Cu and Sn-Sb-Co deposited on copper foil and treated by the post electrodissolution were tested for anodes of Li-ion batteries. It was found that the electrochemical performance of the samples after electrodissolution treatment is significantly improved. The performance improvement of Sn-Sb-Co is better than that of Sn-Sb-Cu alloy.Chapter four focus on Sn-Ni alloy material synthesizd by co-electrodeposition of Sn-Ni alloy and multi-walled carbon nanotube (MWCNTs). It was found that incorporation of MWCNT can greatly change the morphology of the deposited alloy. Both the electric conductivity and structure stability can be improved upon addition of MWCNTs. And great improvement in charge-discharge rate and capacitance retention can be achievied.The major content of chapter five is about the electrochemical performance improvement of transition metal oxide (Fe3O4). By using the the method of designing porous structure and adding carbonaceous material in combination, the electrochemical performance of the material is successfully improved. Multi-walled carbon nanotube-reinforced porous iron oxide (Fe3O4/MWCNT) is synthesized by a two-step approach with porous Cu substrate serving as current collector. Porous Cu substrate is prepared through electroless deposition with hydrogen bubble serving as template. Fe3O4/MWCNT composites are prepared by the electrodeposition of Fe3O4 in the presence of dispersed MWCNTs. Porous structure provides extra space for buffering the volume change and the conductivity of the material is improved by using porous Cu substrate and adding MWCNTs. When used as anode of Li-ion battery, the material gives improved cycling capacity and rate performance. |
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