Zhang Guangzhao, Yang Yu, Chen Yunhua, Huang Jun, Zhang Tian, Zeng Hongbo, Wang Chaoyang, Liu Gao, Deng Yonghong
Department of Materials Science and Engineering, Southern University of Science and Technology, Shenzhen, 518055, China.
Research Institute of Materials Science, South China University of Technology, Guangzhou, 510640, China.
Small. 2018 Jun 22:e1801189. doi: 10.1002/smll.201801189.
With extremely high specific capacity, silicon has attracted enormous interest as a promising anode material for next-generation lithium-ion batteries. However, silicon suffers from a large volume variation during charge/discharge cycles, which leads to the pulverization of the silicon and subsequent separation from the conductive additives, eventually resulting in rapid capacity fading and poor cycle life. Here, it is shown that the utilization of a self-healable supramolecular polymer, which is facilely synthesized by copolymerization of tert-butyl acrylate and an ureido-pyrimidinone monomer followed by hydrolysis, can greatly reduce the side effects caused by the volume variation of silicon particles. The obtained polymer is demonstrated to have an excellent self-healing ability due to its quadruple-hydrogen-bonding dynamic interaction. An electrode using this self-healing supramolecular polymer as binder exhibits an initial discharge capacity as high as 4194 mAh g and a Coulombic efficiency of 86.4%, and maintains a high capacity of 2638 mAh g after 110 cycles, revealing significant improvement of the electrochemical performance in comparison with that of Si anodes using conventional binders. The supramolecular binder can be further applicable for silicon/carbon anodes and therefore this supramolecular strategy may increase the choice of amendable binders to improve the cycle life and energy density of high-capacity Li-ion batteries.
硅具有极高的比容量，作为下一代锂离子电池的阳极材料引起了广泛关注。然而，硅在充放电循环过程中会发生较大的体积变化，这会导致硅粉化并随后与导电添加剂分离，最终导致容量迅速衰减和循环寿命不佳。在此，研究表明，通过丙烯酸叔丁酯与脲嘧啶酮单体共聚然后水解简便合成的自修复超分子聚合物的应用，可以大大减少硅颗粒体积变化引起的副作用。由于其四重氢键动态相互作用，所获得的聚合物具有优异的自修复能力。使用这种自修复超分子聚合物作为粘合剂的电极，初始放电容量高达4194 mAh/g，库仑效率为86.4%，在110次循环后仍保持2638 mAh/g的高容量，与使用传统粘合剂的硅阳极相比，其电化学性能有显著改善。这种超分子粘合剂可进一步应用于硅/碳阳极，因此这种超分子策略可能会增加可用于改善高容量锂离子电池循环寿命和能量密度的粘合剂选择。
