Application Research On Nano-material As Anode Electrode For Lithium-ion Battery

Nano-material has much excellent characters and potential technological applications. It becomes the research frontier in the scientific fields such as physics, chemistry, biology etc. And apply nano-materials as electrode for lithium ion battery is a very important topic in current research activities. Lithium ion battery is a new generation green non-pollution battery when it was used in the 1990s. It is widely used in portable electron apparatus and cars due to its highlights, such as high voltage, low discharge rate by itself, little volume, light weight and non memory effect, but the anode materials for lithium ion batteries are the key to constrain its whole performance. The lithium-ion batteries which used early almost select carbon/graphite as the anode material. But when discharge for the first time, there are passivation membrane on the surface of carbon, which will cause capacity lose. Moreover, the potential of carbon is very close to that of lithium, when overcharge, the metal lithium will separate out on the surface of carbon, which is the intrinsic safety we must concern. And it low in the theory capacity. The need for high-energy and lighter lithium-ion battery product promotes the search for new anode materials.In this article, we first introduce the fundamental concepts, development histories, properties and characteristic technologies of nanomaterials, and the research and development of anode materials for lithium batteries has been reviewed; as well as the main application potentials and synthetic strategies of TiO₂,NiO,Li₄Ti₅O₁₂,Sn-CNTs. The microstructure and electrochemical performance were characterized by XRD,SEM,TEM and constant current charge-discharge tests. The detailed works are as follows:(1) Nanocrystalline rutile TiO₂ particles were direct synthesized by 300—400℃pressure-thermalcrystallization method using TiCl₄ as the source material in the condition of acid. The characteristics of the powders were studied by XRD, TEM. The results showed that the high temperature and pressure are good for nanocrystalline TiO₂ forming. The size of the particles ranges from 10 to 300nm, and square apparent structure. The formation, morphology and particle size of rutile TiO₂ isn't change after treated in the high temperature. Electrochemical performance study shows that TiO₂ is not a good anode material for lithium-ion battery.(2) Anode materials NiO for Li-ion battery were synthesized by hydrothermal method with Ni (NO₃)₂ and NaOH as raw materials. Main reaction mechanism was determined by TG-DSC analysis. The structure and electrochemical performance of NiO were characterized by XRD and the constant current charge-discharge tests. NiO sintered at 400℃was cubic structure. Its initial discharge specific capacity was 1151 mAh/g at the constant current of 0.1mA/cm².The reversible capacity maintained 776 mAh/g after 20 cycles. NiO is an excellent anode material for lithium-ion batteries.(3)The precursors of L₄Ti₅O₁₂ were prepared from tetrabutyl titanzte and lithium acetate by sol-gel process. The L₄Ti₅O₁₂ samples were synthesized by calcining the gel precursors at 500～800℃in air for 10～20h. Its reaction mechanism was investigated by thermogravimetry(TG) and X-ray diffraction(XRD) and scanning electron microscopy (SEM). The results showed that the single-phase products were obtained by calcining the gel precursors at 800℃in air for 12h. Electrochemical performance shows that the lithium capacity in the first cycle reached 170.2mAh/g at the constant current of 0.30mA/cm². The reversible capacity maintained 146.5mAh/g after 20 cycles.(4) A series of Sn-CNTs composite was prepared by H₂ deoxidized of SnCl₄ and CNTs with different proportions. The microstructure and electrochemical performance were characterized by SEM, XRD and charge-discharge measurement. Results show that the size of tin particles ranges from 100nm to 300nm, and sphericity apparent structure after H₂ deoxidized in 500℃. Electrochemical performance shows that the capacity in the first cycle reached 850mAh/g at the constant current of 0.15mA/cm². The reversible capacity maintained 450mAh/g after 20 cycles. Sn-CNTs is an excellent anode material for lithium-ion batteries.