关键词: 锂离子电池, 硅基负极, 纳米材料, 体积膨胀, 电化学, 优化设计

Abstract:

Silicon is considered as a strong competitor for the next generation anode materials due to its high theoretical capacity, low lithium insertion potential, wide sources and environmental friendliness. However, the huge volume expansion in the process of lithium ion deblocking leads to the pulverization and fracture of the active material, which leads to a series of problems such as poor cycle performance, fast capacity degradation and even electrode failure. So far, there are a lot of reports about modified silicon materials. This paper will focus on the nanostructured design of silicon-based materials and the combination of silicon/carbon materials. Firstly, the lithium storage and failure mechanism of silicon are analyzed, and the influence of silicon failure on its electrochemical performance is understood from the mechanism. Secondly, we theoretically explained the mechanism of nano-scale silicon materials to alleviate the volume effect, and demonstrated the advantages of nano-silicon materials from the aspects of structure design, material synthesis, morphological characteristics and electrochemical performance. Subsequently, the research progress of silicon-carbon composites was summarized in terms of relieving volume expansion, improving electrical conductivity and forming a stable solid electrolyte (SEI) film. In addition, the mechanism of electrochemical performance enhancement by introducing conductive polymers and metals into silicon-based materials is also discussed. Finally, several suggestions are put forward for the industrial application of silicon-based materials in terms of improving the first Coulomb efficiency, SEI film stability and mass loading capacity.

Key words: lithium-ion battery, silicon-based anode material, nanomaterial, volume expansion, electrochemistry, optimal design