Self-Healing Chemistry between Organic Material and Binder for Stable Sodium-Ion Batteries

Abstract

Summary One of the major challenges for high-energy sodium-ion batteries is the mechanical fracture triggered by large volume change. To circumvent pulverization-induced capacity decay, self-healing chemistry between binder and active material is critical but is never reported. Here, we report a self-healing electrode with hydrogen bonding between an oxygen-rich active material, sodium rhodizonate dibasic (SRD), and a hydroxyl-rich binder, sodium alginate (SA). During the sodiation of microsized SRD, cracks induced by volume expansion expose a new oxygen-rich surface, whereas the SA binder fills these cracks under pressure generated by volume expansion and binds the pulverized SRD together by hydrogen bonding between SRD and SA. Self-healing between hydroxyl-rich binder and oxygen-rich active material is a universal strategy for mitigating the pulverization-induced capacity decay of active materials, as demonstrated by the longer cycle life of the SRD electrode with other hydroxyl-rich binders, polyacrylic acid, and xanthan gum than with hydroxyl-free polytetrafluoroethylene binder.