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

摘要：

硅具有高的理论比容量、较低的嵌锂电位、来源广泛且环境友好等优点，被认为是下一代锂离子电池负极材料的有力竞争者。然而，在锂离子脱嵌过程中巨大的体积膨胀引起了活性材料的粉化和破裂，这带来了电极循环性能差、容量衰减快甚至电极失效等一系列问题。迄今为止，有大量关于改性硅基材料的报道。本文将重点介绍硅基材料的纳米结构化设计和硅/碳材料的结合。首先，分析了硅的储锂及失效机制，从机理上理解硅的失效对其电化学性能的影响。其次，从理论上阐述了纳米级硅材料对缓解体积效应的机理，从结构设计、材料合成、形态特征和电化学性能等方面论证了纳米硅材料的优势。随后，从缓解体积膨胀、提高电导率和形成稳定的固体电解质（SEI）膜等方面总结了硅碳复合材料的研究进展。此外，还讨论了将导电聚合物和金属引入硅基材料的电化学性能增强机理。最后，从提高首次库仑效率、SEI膜稳定性和质量负载量等方面对硅基材料的产业化应用提出几点建议。

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