Preparation And Exploration On Properties Of Anode Materials Of Novel Iron-Based Lithium-Ion Battery With High-Capacity

The demand for high output lithium secondary batteries is rising because cell phones, portable computers, power tools are getting popular, as well as the expansion of electric vehicles, energy storage market.The commercialized carbon anode material is unable to meet the demand due to its low theoretical capacity (372 mAh g’1), thus, people begin to develop other non-carbon anode materials with high-capacity actively. As one of the most promising materials, transitional metal oxides anode nanomaterials are considered an alternative to commercial carbon anode material for its high specific capacity, low cost, natural abundant storage capacity, etc. However, the practical application of the transitional metal oxides material is hampered by its relatively low electron conductivity and diffusion of lithium ion. What’s more, the intercalation/ deintercalation process of has great volume effect, leading to the poor rate performance and cycling performance. The rate performance and cycling performance can be improved by the synthesis of transitional metal oxides with special morphology nanostructures or preparation of the composite nanostructure. This is because that the nanostructure with special morphology possesses large specific surface area, expanding the contact area between the active material and the electrolytic solution, shortening electron and lithium transport path. The combination of the transitional metal oxides and carbon material has not only increased electronic conductivity of the material, but also effectively alleviated its volume expansion effect during intercalation/deintercalation process. In this paper,the main rersearch is that preparation of iron-based transition metal oxides such as Fe3O、CoFe2O4、Fe2O3 and their Lithium storage performances1) Fe3O4-PANI composites are deposited directly on the spumescent nickel surface by the in-situ polymerization of aniline followed by thermal annealing. After heating treatment, polyaniline in situ converts to amorphous carbon, which can prevent particle agglomeration caused by high temperature treatment, forming carbon-coated Fe3O4 nanoparticles. The resultant Ni@Fe3O4-C is applied as the integrated electrode without blocking agentsin lithium-ion battery. The carbonization of polyaniline makes itself a three-dimensional network structure, effectively ensuring fast-moving of electrons during charging and discharging. The unique structure of Ni@Fe3O4@C has effectively improved its electrochemical properties, At the current density of 100 mA g-1,Ni@Fe3O4-C remains the capacity of 859.3 mAh g-1 after 30 cycles. The capacity retention rate is 98.3% compared with the initial capacity, which indicates the good cycling stability and high specific capacity.2) The hollow structures of one-dimensional ternary transitional metal oxides CoFe2O4 nanotubes are prepared by the self-templating method with Kirkendall effect. Because of its unique structural features, CoFe2O4 nanotubes have good reservoir properties of lithium. At the current density of 100 mA g-1, it still maintains a high charging specific capacity of 988 mAh g-1 after 100 cycles. The capacity retention rate is 95% compared with the specific capacity (1036 mAh g-1) in the 1st cycle. In addition, the actual capacity of CoFe2O4 is higher than the theoretical value due to its particular hollow tubular structure and large surface area. Its capacity remains 680 mAh g-1 after 500 cycles at the high rate of 1 A g-1, indicating its good rate capability and excellent cycle stability.3) The porous Fe2O3 nanorods composed of carbon-shell and Fe203-core are synthesized by Stober method. Experimental results show that this particular nanomaterials of Fe2O3 with core-shell structure displays a very high lithium storage potential while decays quickly in the initial charging and discharging. However, the capacity rises along with the cycling times. For example, the capacity increases to 720 mAh g-1 after 524 cycles, representing a prospect in lithium storage.