Zwitterionic Polymer Binder Networks with Structural Locking and Ionic Regulation Functions for High Performance Silicon Anodes

The silicon anode suffers from significant volume expansion, low electrical conductivity, and poor long-term cycling performance, which collectively limit its potential to replace graphite as the anode material for lithium-ion batteries. In this article, a PAA-p(HEA-SBMA) binder was prepared by an in situ thermal cross-linking method, which combines strong mechanical properties and excellent reaction kinetics. The synergy of covalent bonding, dynamic hydrogen bonding, and ionic interactions in the binder structure provides excellent mechanical strength, which effectively dissipates stresses and "locks" the entire structure. In addition, the zwitterionic monomers in the binder structure improve the transport of lithium-ions and promote lithium salt dissociation, which helps to establish a stable solid electrolyte interphase (SEI). Thanks to the structural locking mechanism and dynamic ionic regulation function, the PAA-p(HEA-SBMA) binder exhibited a long cycling performance. Even after 1000 cycles at 0.5 C, it still has a discharge capacity of 981.63 mAh g^-1. The multifunctional binder designs in this work provide insights into the advancement of high energy density lithium-ion batteries.