Preparation And Application Of Nanosized Tin/Carbon Composites In Lithium-Ion Batteries

Recently, lithium-ion batteries have been considered as an ideal power source due to their high energy density, high operating voltage and non-pollution. Generally, the performance of any device depends intimately on the properties of the materials of which it is formed; this also holds for lithium batteries. Anode is one of the keys of lithium-ion batteries. Sn-based anode materials with a high specific capacity of 994 mAh/g have attracted immense interests. A major drawback, however, affects these materials to practice, that is, the large volume expansion that accompanies the lithium alloying-dealloying process. These volume variations result in severe mechanical strains that greatly limit the cycling life of the electrodes. One of the most promising ways is to disperse the nanometer-sized tin-based materials into a carbon matrix. However, owing to the low melting point of tin, highly dispersive tin nanoparticles in a carbon matrix are still a challenge. This experiment provides a one-step, controllable preparation method. A new Sn/C composite material for lithium-ion battery anode was synthesized by carbonization and carbothermal reduction with phenolic resin as carbon source and stannous chloride or stannous sulfate as the tin source. The morphology and structure were systematically measured by transmission electron microscope (TEM), high resolution transmission electron microscope (HRTEM), X-ray diffraction (XRD) and thermogravimetric-differential scanning calorimetry (TG-DSC) measurements. The electrochemical properties were measured via galvanostatic charge and discharge and cyclic voltammetry. The relationships between the synthesis condition, morphology and structure of composites and their electrochemical properties were revealed. It had great academic and practical essences for the promotion of anode materials with high capacity for lithium-ion batteries.The results showed that the synthesis condition and the content of tin in composites had immense influence on the morphology, structure and electrochemical properties of composites. The sample heated in 600℃for 1h shows the highest capacity and the best cycle performance. At optimized condition, stannous chloride and stannous sulfate could deliver the reversible capacities of 403 and 495mAh/g, respectively, when they were used as the source of tin, which revealed great potential application in lithium-ion batteries.