Ion-conductive self-healing polymer network based on reversible imine bonding for Si electrodes

Si electrodes have attracted considerable attention as materials for next-generation lithium-ion batteries owing to their high theoretical capacity and natural abundance. However, many limitations must be overcome before Si electrodes can be commercialized, particularly the steady degradation in battery performance caused by large volume changes in the active material. Here, an ion-conductive self-healing polymer binder is developed for high-performance silicon electrodes. Glycol chitosan with dialdehyde-terminated polyethylene glycol as a macrocrosslinker is used in a simple process to form the crosslinked polymer network based on imine double bonds, which further improves ion conductivity. Strong and reversible imine double bonds in the crosslinked polymer provide self-healing ability. Si electrodes using the developed polymer network results in an initial Coulombic efficiency of 82.2%, a discharge capacity of 2141 mAh g-1 after 150 cycles, and a reversible capacity of 2700 mAh g-1 at a current density of 3C. These outstanding electrochemical performances demonstrate that the selfhealable network and ion-conductive functionality of the developed polymeric binder significantly improves the operation of Si electrodes.