Preparation And Electrochemical Properties Of Carbon Encapsulated Si-Based Composites

This paper summarized the research situation of the Li-ion battery, and particularly reviewed the research status of silicon-based negative material for lithium ion battery. Based on summarizing the research status,the pyrolysis method was chosen to prepare Si-Grahite-prolyzed carbon material. Two ways which was treatment by dipped into NaOH solution and eaching the copper current collecter was used to improve the cyclic performance of composite. Through XRD SEM observation, surface configuration, composition and structure of the products were studied. Through the charge/discharge test and CV experiments, the electrochemical performance was investigated.Si/G/C pyrolyzed carbon material was prepared by pyrogenation process. In the experiment, the mass ratio of pyrolyzed carbon was fixed. The morphology stability of Si/G/C composite electrode is enhanced significantly in comparison with pure Si composite. It is founded that the composite with a Si:G weight ratio of 5:5, which has the first reversible capacity of 1276.5 mAh·g^-1 and remain 512.8 mAh·g^-1 after 40 cycles, shows the best performance,. After the heat treatment of electrode, the cyclic performance can be improved. The cyclic performance of prepared composites can not be obviously improved by the second pyrogenation. Additionaly, The SiMn/C composites prepared by the pyrolysis and ball milling has the first reversible capacity of 245.6 mAh·g^-1 and remain 512.8 mAh·g^-1 after 40 cycles.Two mathods was chosen to improve the electrochemical performance of the composites, which was treatment by dipped into NaOH solution and eaching the copper current collecter. The composites after the treatment of NaOH have good cyclic stability and a low reversible capacity. The cyclic performance of Si/G/C composites can be obviously improved when the copper current collecter is etched by FeCl₃ solution. . It is founded that the composite with a Si:G weight ratio of 4:4 exhibits excellent performance. The composite has the first reversible capacity of 1012.9 mAh·g^-1 and remain 660.2 mAh·g^-1 after 40 cycles.