| Lithium-ion secondary battery has arised in people expect to create the environment friendly, conservation of resources, sustained harmonious society calls at the historic moment. With its excellent electrochemical performance,Lithium-ion secondary battery get recognized gradually by people, and widely used in electronic products, transportation equipment power supply, aerospace standby power, military equipment as well as the energy storage device, and many other aspects.In today’s battery development, the anode materials for a major change, had walked to the front of the battery anode materials, so in the current stage of the development, the development speed of the lithium ion battery direct depends on the development speed of the battery anode materials.At present, commercial lithium ion battery, is still main using LiCoO2, but LiCoO2materials who lead to the environmental pollution,with not enough resource,and high cost, make the development of the lithium ion battery into the bottleneck,so looking for better battery anode materials instead of LiCoO2has become an inevitable trend.The author is so happy to get the simple modification studies in LiMn2O4and LiFePO4,which are most popular in the current lithium ion battery positive materials research, also will be the most two promising materials to replace LiCoO2to be new battery anode materials.In this paper the first chapter, analyzed and summarized lithium batteries development situation, and simple introduces the work principle of lithium ion batteries, and lithium ion battery present application status, then instructions several of the most common battery anode materials, also points to the carbon nanotubes, and introduced carbon nanotubes, and finally summarizes the research content.The second chapter basically introduced use material, equipment, process technology in this experiment, as well as the use of the testing and analysis method.In the third chapter, study on carbon nanotubes the purification process, we found that the microwave processing can remove impurities CNTs amorphous carbon,and acid treatment can go away with during the preparation of residual metal catalysts such as impurity, after these means treatment,carbon nanotubes purity could to be above97%. And then, and the way through cross contrast, after analyzed and compared all sorts of decentralized treatment process, research shows that ball mill process can control the CNTs length-diameter ratio, the airflow can make CNTs scattered scattered more thoroughly, etc.In the fourth chapter, useing CNTs as a carbon source,to research the carbon coating modification on LiMnO4.A study suggests that the materials on synthesis process and the CNTs addition amount, to the surface of the material in the positive CNTs conductive shaped grid has a great influence.In LiMn2O4study, dry high-speed ball integration into process is more advantageous to the conductive grid formation,and with1%CNTs in the LiMn2O4, electric grid is formating bestly, its circulation performance got rise significantly, circulation attenuation to obtain the very good under control.In the rate by0.2C discharge conditions, although its initial discharge capacity has a little decrease from the original125mAh/g down to the later117mAh/g, but its capacity attenuation just10times the cycle is from the original attenuation9%to modified directly dropped to3%, capacity rate attenuation has significantly down slowly, and doping1%of carbon powder capacity attenuation also have close to8%, far higher than the1%of the carbon nanotubes doping. |
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