| Lithium-ion batteries are currently the most widely used portable power supply system. How to further improve the energy density has become an important research subject. At the same time, compared with other kinds of batteries, the raw materials cost and fabricating cost of lithium ion batteries are much higher. Meanwhile, several key component materials in the lithium ion batteries are nonrenewable or toxicity, which could make bad effects on the environmental protect. Therefore, with the purpose to improve those problems, this paper tries to use biological materials manufactured products (Rice paper) to partly replace some of the key component materials in the lithium ion batteries.Chapter1is a general introduction including the development of battery, working principle and components of lithium ion batteries, the use of natural materials in lithium ion batteries and principle of rice paper. Chapter2presents the main experimental reagents and the test equipment we used in this thesis.Rice paper is one kind of non-woven fibrous membrane which is made from fibers of some certain plants. It has been used for traditional Chinese painting and calligraphy since Tang Dynasty. Unique structure of the raw materials and papermaking process bring rice paper the unique functions, such as wettability, durability, deformation and insect resistance. Among the functions, the wettability attract our attentions well. As one of the key components in the lithium ion batteries, separator is required to have excellent wettability with the electrolyte. Therefore, in Chapter3, with the help of the wettability of rice paper, we tried to use the rice paper as the separator in the lithium ion batteries. The results of this study indicate that the rice paper membrane is electrochemically compatible with several widely used or investigated electrode materials and an electrolyte solution for lithium-ion batteries and the cells with the rice paper membrane as the separator show good electrochemical performance.In Chapter4, we carbonize the rice paper to obtain a hard carbon film through a pressure sintering method. The carbon has a three-dimensional porous structure and is used as a free-standing anode for lithium-ion batteries.In Chapter5,6and7, we tried to synthesized several kinds of carbon membrane-supported thin-film electrode materials, such as LiFePO4/C, 3/C and Li4Ti5O12/C. We get precursor of electrode materials by using solid state reaction method, and coat them on the rice paper. Then through a co-sintering process, the precursor could change to be the electrode materials and the rice paper could be carbonized at the same time. The rice paper-derived carbon can be used not only as the current collector but also as the three-dimensional electronic conduction network for active materials. These carbon-supported film electrodes not only exhibit improved rate performance but also cut down both the complexity and the cost of the fabrication process.Based on the rice paper, we prepared the separator, negative electrodes and positive electrodes for lithium ion batteries. In Chapter8, we design and assemble a new rice paper-based lithium ion battery and test its electrochemical performance.In Chapter9, lithium-ion conductor Li1.3Al0.3Ti1.7(PO4)3with an ultrapure NASICON-type phase is synthesized by a1,2-propylene glycol (1,2-PG)-assisted sol-gel method. Due to the use of1,2-PG, a homogeneous precursor solution is obtained and the well crystallized Li1.3Al0.3Ti1.7(PO4)3can be prepared at a much lower temperature. The lithium ionic conductivity of the sintered pellets is up to3.0x10-4S cm-1at50℃.Finally, in Chapter10, we make a brief summary on the achievements and the deficiency in this thesis. Some prospects and suggestions of the possible future research directions are pointed out. |
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