In Situ Self-Healing of Gel Polymer Electrolytes Enhancing the Cycling Stability of Lithium Ion Batteries

Gel polymer electrolytes (GPEs) for lithium ion batteries (LiB) have received massive research attention. One critical issue for GPEs is damage of GPEs and GPE/electrode interfaces in charging/discharging cycles. To address this issue, dissociative covalent adaptable networks (CANs) are incorporated to GPEs to bring dynamic features and self-healing ability to the GPEs. Based on the thermally reversible property of Diels–Alder adducts of furan and maleimide groups, dissociative CANs were prepared by employing a trifunctional furan (TF) and a trifunctional maleimide (TMI) as monomers. The GPE was prepared through an in situ cross-linking reaction of TF and TMI in the presence of liquid electrolytes. The dissociative CANs possess amine and hydroxyl groups to enhance the compatibility between the cross-linked polymer matrix and liquid electrolytes as well as the liquid electrolyte content of the GPE. In the cycling charging/discharging operation, autonomous recovery of capacity loss was observed with the LiB cells. Moreover, the cells also demonstrated long-term stability of 500 cycles at 2 C without a significant capacity decay. The self-healing ability of the GPE, performed with the de-cross-linking and re-cross-linking behavior of TF/TMI dissociative CANs, contributes to the above-mentioned performance of the LiB cells.