Poly(ionic liquid)@PEGMA Block Polymer Initiated Microphase Separation Architecture in Poly(ethylene oxide)-Based Solid-State Polymer Electrolyte for Flexible and Self-Healing Lithium Batteries

PEO-based solid electrolytes are eagerly anticipated for being explored in batteries with remarkable performance. Their narrower electrochemical window and weak mechanical strength, however, limit the potential for wide application in safe and high-capacity electronic devices. Herein, a self-healing solid-state electrolyte (PEO@BPIL) is fabricated by the incorporation of an imidazolium-based polymerized ionic liquid (poly(ethylene glycol) monomethacrylate (PEGMA)) block polymer into PEO, and the influence of copolymer configuration on electrochemical performances of the system is investigated in-depth. In addition to reducing the crystallinity of PEO, an inimitable orderly and orderless microphase separation structure is introduced in PEO@BPIL, which brings about a "green fast track" for Li-ion migration. This contributes to a lithium-ion transference number of 0.63 that is an unsurpassed level. The electrochemical stability window of the optimized PEO@BPIL can achieve 5.0 V (vs Li+/Li). As a result, the capacity and endurance discharge performances for PEO@BPIL based cells are significantly improved. Moreover, the bountiful charged ions on the scaffold endue the electrolyte with generous interactions, conferring the PEO@BPIL predominant adhesiveness toward lithium metal (the hanging weight = 200 g) and standout self-healing ability (recovering time <30 min, 60 °C). The restriction toward lithium dendrite is thus enhanced. The PEO@BPIL-based laminate polymer battery presents ascendant antifolding deformation ability and still exhibits good electrochemical performances after reiterative damage. In combination with the high flame retardancy of polymerized ionic liquid, this work affords a splendid idea for an emerging power supply battery.