The Synthesis And Modification Of Lithium Terephthalate As Anode Material For Lithium Ion Battery

Lithium-ion battery plays a very important role in the field of the battery because of its high energy density and energy conversion efficiency. Nowadays, everyone may use it every day. The electrode materials in the commercial products are inorganic materials. However, there are some critical problems for inorganic electrodes. Firstly, it will use up non-renewable resources; Secondly, it will deteriorate our environment; Thirdly, the properties of these materials are hard to be improved because of structural factors and so on; Finally, the ratio of performance to price is low. So we need to look for alternative electrode materials. To our excitement, organic materials can cover the shortages mentioned before. They are diversified, cost-saving and do little harm to our resources and environment. What is more, they have some promising properties. The energy density and energy conversion efficiency are higher and organic electrode materials can offer better safety and reliability. Among these materials, the conjugated carbonyl organic material has been intensively investigated. They not only own these advantages mentioned before but also have some flexibility on structure and function, which is good for commercial application. However, the knowledge of these materials is limited and there are some unknown issues. So in this thesis, I choose one conjugated carbonyl compound as the object of my study.In this thesis, I have investigated the properties of lithium terephthalate systematically. Firstly, I gain pure lithium terephthalate by neutralization reaction. The size of the particles is big and also their electrochemical performance is bad. The color of lithium terephthalate will change after heat treatment where the temperature is lower than its thermal decomposition temperature. So the heat treatment temperature is ranged from 400 centigrade to 500 centigrade. For the thermally treated samples, the first cycle capacity will decrease and rate performance is not improved. However, the cycling stability and the first cycle columbic efficiency are increased slightly. What is more, the sample which is heated at 400 centigrade shows the best performance. On the other hand, lithium terephthalate is suffering from the low electronic conductivity. So I choose glycine as coating resource and investigate the influence of additive amount on electrochemical behavior. The result shows that the electrochemical performance is improved gradually with additive amount increasing and the sample with 20wt% additive shows the best performance.I use spray drying method to prepare lithium terephthalate based composites. The concentration of precursor solution can determine the product’s morphology and size. The result shows that the morphology is related with the electrochemical performance. Following that, I try to combine coating method with spray drying method to further improve the performance. Here I choose glucose, glycine and sulforea as the coating resources, whose additive amount is the same(20%). After mixing with the precursor solution, the spray drying method creates sphere particles. The sample coated with glycine shows the best electrochemical performance.High energy ball milling is a common way of creating sub-micrometer and nanometer particles. By optimizing the ball-milling time, the particle size can be reduced. The electrochemical performance of the samples with 10 h ball milling is the best.