Tin Oxide Array Electrode Preparation And Electrochemical Performance As A Lithium Anode

Lithium-ion batteries are widely used for their excellent performance. The electrode material is critical in a battery. Traditionally, anode is made from graphite and carbon. Tin-based alloys have drawn much attention because the high capacity compared to graphite. It is one of the most promising electrode materials.Tin nano-arrays were successfully prepared by electrochemical deposition using alumina anodic oxide (AAO) as templates, with holes of 100nm in diameter. Tomography and composition of the tin nano-arrays were characterized by SEM and EDS. Crystal structure was determined by X-ray diffraction and selected area diffraction (SAED) on a transmission electron microscopy. The result showing:tin nano-arrays are standing on the surface of copper substrate; The nano wires has diameter of 330nm and length about 30μm after the deposition of 20min. The TEM observation and SAED indicate that nano-arrays have single crystal structure which preferred along the [200], [400] crystal plane. The prepared tin nano-array has tetragonal structure.Cyclic voltammetry were applied to reveal the electrochemical performance of tin nano-arrays, when it was used as electrode of Li-ion battery. The electrodes of tin nano-arrays are very active and have good structure stability, with compare to electrode of tin film. SEM observation found the tin nano-arrays keeps unchanged after tens cycling. It means the tin nano-array electrode has enough space to accommodate the volume change in the process of charging and discharging. The dynamic character such as number of electrons transferred, polarization resistance, and exchange current density of the tin electrode were calculated. The mechanism of the intercalation of Li+ into electrode was discussed.Cyclic voltammetry was also applied to tin membranes directly deposited on copper. The results showed that discharge capacity of membrane electrode gradually increases. Observation by SEM found that morphology of the electrode significantly changed after cycling. The increasing of capacity in first few cycles was correlated to the formation of porous structure. The discharge capacity of membrane electrode decreases fast because tin loose contact with the substrate. Apparent shift of the peak potential in CV scans have been found for a tin membrane electrode. While peak potential remain unchanged for tin nano-arrays electrode, indicate better dynamic capability. Tin nano-arrays electrode showed rapid response when scan faster.