| With the rapid development of the modern technology, the increasing need of best development between human and environment and the sharp decrease of the fossil energy, there are higher request for people making use of natural energy and exploring of new energy resources. Because of the advantages of the lithium ion battery, such as high power density, high output voltage, long cycle life, no "memory effect", low self-discharge, environmental protection and portability, it gets a lot of attention of people in the area of storage power and power supply. This paper summarized the research status of the lithium ion battery and its negative materials at present in detail. From the presented data, it can be found that improving the entirety performance and reducing the cost of the lithium ion batteries are the most important research points. With the development of the storage power and power supply, more requirements are put forward. Because of the "Zero strain" performance, Li4Ti5O12 becomes more popular as the anode material of the lithium ion battery in research area. It has stable discharge voltage and excellent cycle performance, and can avoid the decomposing of the electrolyte and producing the interface film, and high security performance, which attract much interest of the science researchers. Unfortunately, due of the poor conductivity, its discharge capacity is poor. In this paper, the author focuses on improving the conductive performance to receive the high capacity and cycle steadily anode materials for lithium ion batteries. At the same time, the author picks up different cathode materials with Li4Ti5O12 as anode material to make the lithium ion battery for researching to find out the suitable cathode material for Li4Ti5O12.In the thesis, Li4Ti5O12 was synthesized by high power ball milling together with heat treatment with the nano-P25 as titanium resource. The samples were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The composite electrode of Li4Ti5O12/carbon nanotubes(CNTs) was investigated by electrochemical impedance spectrascopy(EIS), cyclic voltammetry(CV) and charge-discharge tests. The result indicated that Li4Ti5O12 with excellent cycle performance was synthesized under the heat treatment temperature of 800℃ and the treatment time of 8h adopting nano titanium reactant.Li4Ti5O12 was synthesized through doping in the raw materials with organic carbon compounds. The doping ratio chose to research was 1:1 and 2:1 of Li4Ti5O12 between dopant. The results showed that it wouldn’t introduce the impurity into the sample when doped in the raw material. And, the suitable amount of doping was benefit for getting the sample of excellent performance.Li4Ti5O12 doped with CNTs was synthesized by doping CNTs into the raw materials in the vacuum atmosphere. The doping ratio chose to research was 1:94,3:92,5:90 and 7:88 of the ratio of CNTs and Li4Ti5O12. It found that the product with doping ratio of 7:88 had the excellent performance in first charge-discharge and cycle performance. Its first discharge capacity was 182.1 mAh. g-1.Li4Ti5O12 doped with carbon was synthesized by doping CNTs or organic carbon compounds into the raw materials in the vacuum atmosphere. The doping ratio of CNTs was 1:94,3:92,5:90 and 7:88 of the ratio of CNTs and Li4Ti5O12, and the organic carbon was 1:1 and 2:1.The results with the dopant of CNTs showed that the product with the doping ratio of 3% had the best performance and the first discharge capacity was 200 mAh.g-1.And, the discharge capacity didn’t decrease with different current rate in discharge tests, which showed the excellent cyclic performance. In the study of organic carbon compounds doping, it found that the product with the larger doping ratio had smaller size and excellent first charge-discharge and cyclic performance.LiNi1/3Co1/3Mn1/3O2 was synthesized by solid state method at the different heat treatment system. The results indicated that the samples adopted two step heat treatment system with 550℃ at the first step and 900℃ at the second step had the excellent electrochemical performance.The capacity remained at 90% of first discharge capacity after 50 times charge-discharge cycle at 0.2C.The lithium ion battery was assembled by Li4Ti5O12 anode material and different cathode materials to investigate the electrochemical performance through the ways of EIS,CV and constant charge-discharge.The results showed that lithium ion battery with the anode material of Li4Ti5O12 had an advantage in cycle performance. |
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