Lou Xiaofei, Zhang Yuanyuan, Zhao Li, Zhang Teng, Zhang Hui
College of Mechatronic Engineering, North Minzu University, Yinchuan, 750021, Ningxia, China.
College of Pharmacy, Ningxia Medical University, Yinchuan, 750004, China.
Sci Rep. 2023 Oct 29;13(1):18560. doi: 10.1038/s41598-023-45763-3.
Silicon is considered as the most promising anode material for high performance lithium-ion batteries due to its high theoretical specific capacity and low working potential. However, severe volume expansion problems existing during the process of (de)intercalation which seriously hinders its commercial progress. Binder can firmly adhere silicon and conductive agent to the current collector to maintain the integrity of the electrode structure, thereby effectively alleviating the silicon volume expansion and realizing lithium-ion batteries with high electrochemical performance. In this paper, citric acid (CA) and carboxymethyl cellulose (CMC) are adopted to construct a covalently crosslinked CA@CMC binder by an easy-to-scale-up esterification treatment. The Si@CA@CMC-1 electrode material shows an impressive initial coulombic efficiency (ICE) at 82.1% and after 510 cycles at 0.5 A/g, its specific capacity is still higher than commercial graphite. The excellent electrochemical performance of Si@CA@CMC-1 can be attributed to the ester bonds formed among CA@CMC binder and silicon particles. Importantly, by decoupling in situ EIS combining XPS at different cycles, it can be further proved that the CA@CMC binder can tune the component of SEI which provide a new-route to optimize the performance of silicon.
由于硅具有高理论比容量和低工作电位，它被认为是高性能锂离子电池最有前景的负极材料。然而，在（脱）嵌锂过程中存在严重的体积膨胀问题，这严重阻碍了其商业化进程。粘结剂可以将硅和导电剂牢固地粘附在集流体上，以保持电极结构的完整性，从而有效缓解硅的体积膨胀，并实现具有高电化学性能的锂离子电池。本文采用柠檬酸（CA）和羧甲基纤维素（CMC），通过易于放大的酯化处理构建了一种共价交联的CA@CMC粘结剂。Si@CA@CMC-1电极材料在初始库仑效率（ICE）方面表现出色，达到82.1%，在0.5 A/g下循环510次后，其比容量仍高于商业石墨。Si@CA@CMC-1优异的电化学性能可归因于CA@CMC粘结剂与硅颗粒之间形成的酯键。重要的是，通过在不同循环下将原位电化学阻抗谱（EIS）与X射线光电子能谱（XPS）解耦，可以进一步证明CA@CMC粘结剂可以调节固体电解质界面（SEI）的成分，这为优化硅的性能提供了一条新途径。
