基于氢键交联的网络状聚合物粘结剂在锂离子电池微米硅负极中的应用

Application of netlike polymer binder based on hydrogen bond cross-linking in micron silicon anode for lithium-ion battery

硅具有极高的理论容量,被认为是最具前景的锂离子电池负极材料。然而硅负极锂离子电池目前还不能商业化应用,主要原因是硅在嵌/脱Li+过程经历剧烈的体积变化,导致电极粉碎。性能优良的粘结剂能够限制硅负极体积变化导致的电极粉碎。合成了一种葡聚糖-异氰酸酯-脲基嘧啶酮(DEX-Upy)的聚合物,并与聚丙烯酸(PAA)物理混合,制备了一种通过氢键交联的网络状聚合物粘结剂PAA-DEX-Upy。此聚合物粘结剂通过网状结构及其极性基团与硅颗粒相互作用共同限制微米硅负极粉碎。PAA-DEX-Upy相比于DEX-Upy和PAA电极表现出良好的循环性能,并且微米硅负极具有较高的首次库仑效率。以成本较低的微米硅作活性材料,更利于商业化应用。

Silicon is considered as the most promising anode material for lithium-ion batteries because of its super high theoretical capacity.However,lithium-ion batteries with silicon anodes cannot be applied in the commercial field because silicon undergoes drastic volume changes dramatically during the Li+insertion/extraction process,which causes the electrodes to be pulverized.Binders with excellent performance will be able to limit the pulverization caused by the volume change of silicon anode.In this paper,a dextran-isocyanate-ureido pyrimidinone(DEX-Upy)polymer was synthesized,then physically mixed with polyacrylic acid(PAA)to prepare a network polymer based on crosslinked bond by hydrogen bonds,named PAA-DEX-Upy.The polymer binder restricted the pulverization of the micron-size silicon anode through the interaction of its network structure and polar groups with the silicon particles.Compared with DEX-Upy and PAA electrodes,PAA-DEX-Upy electrode showed a good cycle performance,and the micron-size silicon anode had a higher first-time coulombic efficiency.In this paper,the low-cost micron-size silicon was used as an active material,which was more conducive to commercial applications.