高性能硅基负极聚合物粘结剂的研究进展

Advances of High-Performance Polymer Binders for Silicon-Based Anodes

硅(Si)由于其具有超高理论比容量而成为最有前途的下一代锂离子电池的负极材料。但是,锂离子的嵌入和脱出会造成硅体积的巨大变化,进而导致Si的粉化,致使电极容量产生不可逆的衰减,严重限制了硅基材料的广泛应用。然而过去的大量报道表明,聚合物粘结剂可以有效克服由于硅微粒的体积膨胀而产生的“孤岛效应”,保持电极在充放电过程的完整性,进而提高电极的电化学性能。对聚合物粘结剂按结构分类,可以将其大致分为4类,即线型、支化型、交联网络型及共轭型。不同分子结构的粘结剂用作硅基负极粘结剂时,电极表现出不同的电化学性能。特别是设计出具有多种分子结构的聚合物粘结剂,极大地促进了硅基负极的实际应用。通过对比具有不同分子结构的聚合物粘结剂用于硅基负极取得的效果,可以清晰地得到最有效的分子结构,对未来硅基负极聚合物粘结剂的开发提供思路。最后,本文提出了下一代聚合物粘结剂的设计方向,以促进其向可大规模应用和工业化生产的方向发展。

Silicon(Si)has become the most promising anode material for the next generation lithium-ion battery because of its ultra-high theoretical specific capacity.However,the intercalation and removal of lithium-ions will cause a great change in the volume of silicon microparticles(SiMP),which will lead to the pulverization of SiMP and irreversible attenuation of electrode capacity,which seriously limits the wide application of silicon-based materials.A large number of reports in the past have shown that polymer binder can effectively overcome the“island effect”caused by the volume expansion of SiMP.It could maintain the integrity of the electrode in the charge-discharge process,and then improve the electrochemical performance of the electrode.According to the structure classification of polymer binders,they can be roughly divided into four categories,linear,branched,cross-linked and conjugated.When the binders with different molecular structures are used as silicon-based negative electrode,the electrodes show different electrochemical properties.Particularly,when polymer binders with multiple molecular structures are designed,the practical application of silicon-based negative electrodes will be greatly promoted.By analyzing the effects of various polymer binders on the electrochemical properties of silicon anode,the differences of binders with different molecular structures can be clearly obtained,and then provide ideas for the development of silicon anode polymer binder in the future.Finally,this paper proposes the design direction of the next-generation polymer binder to promote its development towards large-scale application and industrial production.