Self-healable, super Li-ion conductive, and flexible quasi-solid electrolyte for long-term safe lithium sulfur batteries

A couple of self-healable polymer quasi-solid electrolytes (PSEs) were synthesized from poly(arylene ether sulfone) co-grafted with polyureidopyrimidinone and poly(ethylene glycol) (PAES-g-PU/2PEG) and PAES co-grafted with poly(1,2-bis(ureidoethylenemethacrylateethyl) disulfide) and PEG (PAES-g-PUS/2PEG) for long-term stable lithium sulfur battery (LSB) applications. The synthesized self-assemblable PSEs exhibited a high Li-ion conductivity of 0.712 mS cm −1 and tensile strength of 2.2 MPa at room temperature. As their self-healability is enabled by hydrogen and/or disulfide bondings, a high self healing efficiency of ∼95.3% in the ultrafast healing time of 5 min was achieved. The second self-healed PAES-g-(PUS/2PEG) membranes also exhibited a high conductivity of 0.659 mS cm −1 with 94.8% retention, Li-transference number of 0.412, and tensile strength of ∼2.14 MPa. Furthermore, those flexible membranes showed high thermal stability (∼200 °C) and interfacial stability without a short circuit after 1000 h cycling at 2.0 mA cm −2 . Under 0.2 C-rate, the LSB cell assembled with the second healed PAES-g-(PUS/2PEG) retained 98.7% of the original discharge capacity of 929.8 mA h g −1 and a coulombic efficiency of 99.5% after 200 cycles. Flexible polymer electrolytes exhibit high self-healing ability via hydrogen/disulfide bonds and simultaneously achieve both high ion conductivity and excellent thermal/mechanical stability via self-assembly for long-term safe lithium sulfur battery.