Nano-structured Anode Materials For Lithium-ion Batteries: Design, Preparation And Property Study

For its excellent performance, the lithium-ion batteries attract extensive attentionof the national research workers and enterprises. In the process of the development ofthe lithium-ion battery, electrode material has become a bottleneck restricting thelithium-ion battery to promote large-scale applications. With the wide popularity ofportable power products and the rapid development of electric vehicles，developmentof lithium secondary batteries with low-cost，high performance，and high safety havebecome the focus of lithium-ion battery industry, especially the traditional carbonanode materials have already can’t meet the need of the next generation of new type oflithium ion battery cathode materials in the specific capacity, energy, etc. Therefore,the development of new height capacity, high stability, high safety, long life, low costof lithium ion battery cathode materials is particularly urgent. And because of theirhigh theoretical capacity, low cost, environment friendly advantages, tin oxides andiron oxide as lithium-ion battery cathode materials become the focus of attention. Butthese materials at present still exist some problems such as low utilization rate, theratio discharge performance difference, circulate life short. The anode material withnanosized and peculiar structure was considered as an appropriate candidate, and atthe same time, the crystal structure, morphology and size of nanometer electrodematerial have important influence on their electrochemical performance. Therefore, itwill be a very significant research subject. In this article, hollow SnO₂@C composite,diamond Fe₂O₃nanoparticles and different morphology Fe₃O₄@C compositenanomaterials were synthesized and characterized. The main work is divided into thefollowing several parts.Using a simple and effective way to synthesis monodisperse, uniform particlesize SnO₂@C composite hollow nanoparticles, then they were characterized bymeans of X-ray diffraction （XRD）, infrared spectrum （FTIR） and transmissionelectron microscopy （TEM）. Electrochemical performance test results show that underthe range of105mA g^-1the first discharge capacity of SnO₂@C composite hollownanoparticles reach to1009mAh g^-1, after100cycle, to808mAh g^-1, which was farhigher than the traditional carbon material theory capacity and has high capacity andgood cycle performance.With cationic surfactant （CTAB） as the template, the diamond-Fe₂O₃material was synthesized by hydrothermal method. The influence of experimental conditionson the size of diamond-Fe₂O₃material was studied. We compared the nanoscale andmicron grade-Fe₂O₃material electrochemical performance, and discovery thatnanoscale material has obvious advantages than micron grade material in capacity andcycle performance. In the same situation, the capacity of nano electrode materialskeep at73%after50times cycle while the micro material is only50%, indicating thatthe nanosized electrode materials is the effective way to promote cell materialelectrochemical behavior.Using high temperature hydrolysis method, size uniformity and gooddispersibility of-Fe₂O₃nanoparticles were synthesised with no water FeCl3as rawmaterials. Then with PAA for carbon source, by controling the sintering temperatureand time, we realized the controllable synthesis of the ball, chain and ring Fe₃O₄@Ccomposite material. We tested the electrochemical performance and discuss itsstructure on the influence of the electrochemical properties. The results of the studyshow that the ring and chain assembling again from the ball Fe₃O₄@C compositematerial can effectively reduce resistance and improve circulation performance, and italso proved that nanoparticles reassembling can also improve its electrochemicalperformance.