Improving the Electrochemical Performance of Li-Ion Secondary Batteries by Optimizing the Sn/C Composite Anode Materials

Abstract

From the history of commercial anode materials, Sn/C-based material is the focus to enhance the cycling performance. A chemical solution method is used to synthesize the Sn compounds / graphite composite anodes. At the first part of this study, the cycle life was enhanced by adjusting various pH values. The multi-phase Sn compound containing Sn 6 O 4 (OH) 4 , SnO 2 , Sn 3 (PO 4 ) 2 were deposited on slices of graphite of sample pH6. They were expected to provide a higher spectator to Sn ratio for improved cycleability. These phases could be reduced to metallic Sn, resulting in buffer matrix during 1 st cycle. Therefore, the sample pH6 exhibited the best of electrochemical performance. For the cell cycled between 0.001V and 1.5V, the 1 st charge capacity was 758 mAhg-1. Even after 50 cycles, the capacity remained higher than 460 mAhg- 1 . Synthesizing Sn compounds / graphite composite anodes at pH6 with different initial Sn concentrations improved the cycling performance in the second part of this study. When the Sn concentration reached 0.12M, multi-phases of Sn compounds were deposited on the slices of graphite and the amount of Sn was the maximum. The agglomeration of Sn clusters was suppressed by buffering agent generated by the multi-phase of Sn compounds containing Sn 6 O 4 (OH) 4 , SnO 2 , Sn 3 (PO 4 )2 . Therefore, the sample Sn0.12 M exhibited the best cycling behavior among all. During cycling between 0.001 V and 1.5 V, the 1 st charge capacity was around 734 mAhg -1 . The capacity remained as high as 440 mAhg-1 even after 50 cycles.