硅基锂离子电池负极材料的容量衰减及改进研究

Improvement of capacity fading of Si-based cathode for lithium-ion battery

硅材料的比容量(Li15Si4,3590mAh/g)是已商用化的石墨负极(LiC6,372mAh/g)的10倍,硅负极的商业化可有效提高单体电芯的容量,已成为当前研究热点。然而,由于硅负极材料在充放电循环时存在400%的体积膨胀,容易导致电极材料粉化开裂而从集流体上剥落,使得活性物质与活性物质、集流体之间失去电接触,同时不断形成新的固体电解质相界面膜(SEI膜),最终导致电化学性能的恶化。本研究从硅负极材料的储锂机理出发,提出硅负极材料锂化/脱锂化产生的体积膨胀效应导致的粉化开裂和SEI膜不稳定问题的最新调控方法和研究方向,为硅负极材料的研究应用提供支持。

Silicon has gained a huge attention in the last decade,because it has a theoretical capacity(3590 mAh·g-1 for Li15 Si4 phase)of ~10 times higher than that of representative graphite(372 mAh·g-1 for LiC6),which attribute to improve the single cell capacity heavily.However,it suffers from fast capacity fading of electrode,loss of contact with the current collector,and loss of active material contact due to continuous volume expansion and contraction of up to 400%during cycling.The mechanism of lithium storage on the issue that the latest technologies and the research progress of large volume effect during alloying/dealloying with lithium led to electrode pulverization cracking and unstable solid electrolyte interface(SEI)layer were discussed,which can provide research support for the applying of silicon cathode materials.