球形 Si/carbon gel@void@C 复合材料的制备及电化学性能

商业用锂离子电池负极为石墨材料,理论容量较低,不能满足现代社会对锂电池高能量密度的要求。硅因具备高的理论容量、合适的电极电位以及地球丰度高等优势,是新一代锂电池负极材料的候选者。但作为锂电负极,硅在脱嵌锂过程中会发生巨大的体积膨胀,且本征电导率较低,限制了其实际应用。利用柠檬酸盐对L-赖氨酸体系改性,强化Fe~(3+)配体的络合效果,获得以碳为包覆层的球形Si/carbon gel@void@C凝胶电极。结果表明,在0.5A/g电流密度下,电极展示出较高的初次充/放电容量(1 828.8/1 508.3mA·h/g)和较高的初始库仑效率(82.47%),300次循环后容量稳定在1 201.3mA·h/g。同时,良好的导电性能使其展现出良好的倍率性能。

Preparation of the spherical Si/carbon gel @ void @ C and research on electrochemical properties of the composite materials

The commercial lithium-ion battery anodes are mainly composed of graphite, but its theoretical specific capacity is low, which far cannot satisfy the future market demand for high energy density lithium-ion batteries. Silicon (Si) has high theoretical capacity, appropriate electrode potential and the advantages of abundant, and is expected to replace graphite as a new generation of lithium-ion battery anode materials. However, Si as the cathode material can produce huge volume expansion in the process of reaction with lithium, and intrinsic conductivity is low, which limits the practical application. In this work, the L-lysine is used to improve the Fe3+ complexation, and a new structure of Si/carbon gel@void@C is successfully prepared. Results show that the new anode material show a prominent electrochemical performance (a high initial charge/discharge capacity of 1828.8/1508.3 mAh/g, a high ICE of 82.47% and a stable capacity of 1201.3 mAh/g after 300 cycles).