Sn-Sb And Si-Sb Composite Anode Materials For Lithium Ion Batteries

Lithium-ion battery anode material is one the key factor for preparation of high-capacity and high-performance lithium-ion battery materials. Currently,commercialized lithium-ion battery anode materials are mainly graphite. Althought having excellent cycle performance, it can not meet the market requirements for high-capacity lithium-ion battery because of its poor theoretical capacity of 372 m Ah/g. For its high theoretical capacity, alloy anode materials have attracted much more attention. But the huge volume exchange in the lithiation/delithiation process undermine the overall structure of the material, reducing the conductivity of the electrode, thereby constraining its application. In this paper, compound method was applied to improve the electrochemical properties of Sn-Sb alloy and immscible Si-Sb alloy materials.1. Chemical corprecition method was applied to prepare the Sn Sb-Zn Ox composite anode materials.Transtition metal oxide Zn O with zero dimensional spherical structure, prepared by chemical reduction precipition method is able to effectively relieve the agglomeration of the Sn Sb alloy particles and acts as buffering matrix for Sn Sb alloy in cycling process, preventing the lost of electric contact between the collector and electrode materials induced by volume expansion. In addition, Zn O has a high theoretical capacity(978 m Ah/g), which could overall improve the specific capacity of the composite materials. The XRD, SEM and electrochemical tests demonstrat that the Sn Sb Zn O0.4 composite anode materials exhibit higher capacity, coulomb efficiency and the best cycle performance, with initial charge and discharge specific capacities of 801.6 m Ah/g and 1064.6 m Ah/g,respectively, while the initial columbic efficiency was 75.3%. The capacity remained751 m Ah/g after 100 cycles and the capacity retention ratio was 92.5%, showing excellent electrochemical performance.2. The Si0.8Sb/C nanofiber was synthesized by high energy ball milling-electrospinning method. The carbonated Si0.8Sb/C fiber has certain anisotropy,good flexibility and electric conductivity, which can not only provide good electric channels for immiscible Si0.8Sb alloy but also serve as a buffer matrix and alleviate the volume expansion of immiscible Si0.8Sb alloy during cycling. Ratio of active substance, temperature and cutoff voltage all affected the electrochemical performance and the cycle efficiency of Si0.8Sb/C composite anode materials. When the mass ratio of Si0.8Sb and PAN was 3:5, the initial discharge capacity was 1128.9m Ah/g,and the initial capacity retention ratio was 67.6%. The discharge capacity remained at 510.7 m Ah/g after 100 cycles, with a capacity retention ratio of 66.9%,demonstrating a good electrochemical performance.