Cai Zhixiang, Hu Shanming, Wei Yue, Huang Tao, Yu Aishui, Zhang Hongbin
Department of Polymer Science and Engineering, School of Chemistry and Chemical Engineering, Frontiers Science Center for Transformative Molecules, Shanghai Key Laboratory of Electrical Insulation and Thermal Aging, Shanghai Jiao Tong University, Shanghai 200240, China.
Laboratory of Advanced Materials, Department of Chemistry, Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Institute of New Energy, Collaborative Innovation Center of Chemistry for Energy Materials, Fudan University, Shanghai 200438, China.
ACS Appl Mater Interfaces. 2021 Dec 1;13(47):56095-56108. doi: 10.1021/acsami.1c16196. Epub 2021 Nov 3.
Silicon (Si) is an auspicious anode material in next-generation lithium-ion batteries due to its exceptional theoretical gravimetric capacity, environmental friendliness, and high natural abundance. However, the practical application of Si anodes remains a "must-solve" challenge because of its drastic capacity fading that results from the inherent property of drastic volume expansion of Si during repeated lithiation and delithiation. Developing binders employed in robust electrodes has been considered an economical and practical method to affect the electrochemical performance of Si-based electrodes. Some natural polymers have demonstrated good adhesive properties with Si-active materials. However, they have limited capacity to keep the structural integrity of electrodes because the network structures solely based on weak hydrogen bonds are susceptible to deformation during cycling. Herein, we develop an covalently cross-linked three-dimensional (3D) supramolecular network and apply it to the Si electrode to improve cycling performance. This network architecture is constructed using furan-modified branched arabinoxylan of corn fiber gum (CFG) and an ionically conductive cross-linker of maleimido-poly(ethylene glycol) (PEG) through the Diels-Alder reaction. The maleimide groups in PEG can react spontaneously with the furan groups in CFG at room temperature without any other stimulation, thus forming strong covalent bonds in the network. The cross-linked CFG-PEG binder has demonstrated robust adhesive properties with Si-active materials and the current collector. The branching of CFG and functional groups of PEG are conducive to improving the lithium-ion conductivity in the silicon anode, resulting in excellent rate performances. The Si anode with a cross-linked CFG-PEG binder exhibits superior cycling stability. As a result, an cross-linking 3D network as a novel binder has a great potential for fabricating an advanced Si anode in next-generation Li-ion batteries.
硅（Si）因其出色的理论重量容量、环境友好性和高天然丰度，是下一代锂离子电池中一种理想的负极材料。然而，由于硅在反复锂化和脱锂过程中固有体积急剧膨胀的特性导致其容量急剧衰减，硅负极的实际应用仍然是一个“必须解决”的挑战。开发用于坚固电极的粘结剂被认为是一种影响硅基电极电化学性能的经济实用方法。一些天然聚合物已证明与硅活性材料具有良好的粘附性能。然而，它们保持电极结构完整性的能力有限，因为仅基于弱氢键的网络结构在循环过程中容易变形。在此，我们开发了一种共价交联的三维（3D）超分子网络，并将其应用于硅电极以提高循环性能。这种网络结构是通过狄尔斯-阿尔德反应，使用玉米纤维胶（CFG）的呋喃改性支链阿拉伯木聚糖和马来酰亚胺-聚（乙二醇）（PEG）的离子导电交联剂构建的。PEG中的马来酰亚胺基团在室温下无需任何其他刺激就能与CFG中的呋喃基团自发反应，从而在网络中形成强共价键。交联后的CFG-PEG粘结剂已证明与硅活性材料和集流体具有强大的粘附性能。CFG的支化结构和PEG的官能团有利于提高硅负极中的锂离子传导率，从而产生优异的倍率性能。具有交联CFG-PEG粘结剂的硅负极表现出卓越的循环稳定性。因此，作为一种新型粘结剂的交联3D网络在制造下一代锂离子电池的先进硅负极方面具有巨大潜力。
