The Preparation And Li Storage Of Porous Structured Tin-based Electrode

The work principle and the development of lithium ion batteries have been described in this dissertation. Tin, one of the most promising candidates for high-capacity anode materials for lithium-ion secondary battery, has received attention due to its high theoretical capacity. In this dissertation, Sn-based matrials were prepared, and their properties were investigated by scanning electron microscopy (SEM), energy dispersive analysis of X-ray(EDAX), X-ray diffraction (XRD) analysis and galvanostatic charge-discharge tests.The Zn coatings were prepared by the electrodeposition using copper foil as current collector. A porous copper film was prepared after thermal treatment at relatively low temperature and chemically dealloying through being immersed in the electrolyte containing5wt%HCl. The results of SEM, XRD and ED AX showed that a three-dimensional porous copper was formed with ligament size of300nm and there were no Zn left.The Sn electrode was prepared by the electrodeposition of Sn on porous copper film. The as-prepared tin film electrode showed larger reversible capacities and obviously improved cycle performance than Sn on planar copper. It presented the reversibale capacity of540mAh/g at a0.1C rate and430mAhg-1at a0.3C rate after50cycles. It was found the volume variations upon cycling were effectively buffered by porous structure.A Ni-Sn electrode was prepared by the electrodeposition of Ni-Sn alloy on the same porous copper film. SEM showed that small Ni-Sn grain(about100nm) were dispered on porous copper film. Both porous structure and smaller size can improve cycling performance. And when cycled at0.1C, it presented the reversibale capacity of420mAh/g after20cycles and420mAh/g at a0.3C rate after50cycles. With Ni additive, the capacity was lower but the retention was higher, almost no decay from Cycle20to Cycle50.