Interfacial self-healing polymer electrolytes for long-cycle solid-state lithium-sulfur batteries

Abstract Coupling high capacity cathode and Li metal anode with the solid-state electrolyte has been demonstrated as an effective strategy for increasing the energy density and enhancing the safety of rechargeable batteries. However, the limited ion conductivity of the solid-state electrolyte, the large interfacial resistance of electrode/electrolyte, and the unconstrained dendrite growth of the Li metal anode are still the main challenges hindering the applications of the solid-state Li-metal batteries (SSLMB). Herein, a poly(ether-urethane) based solid-state polymer electrolyte (SPE) with self-healing property are designed to reduce the interface impedance and achieve high performance SSLMB. Benefiting from the dynamic covalent disulfide bonds rearrangement and the hydrogen bonds between urethane groups, the proposed SPE exhibits excellent interfacial self-healing ability, which can help to constantly maintain well interfacial contact between solid-state electrolyte and cathode/anode electrodes during the whole cycling life. By casting the designed SPE directly on the sulfur-based cathodes and Li metal anode, it can be easily prepared the integrated solid-state electrolyte/electrode structures, and then assembled them into full cells. As a result, the Li||Li symmetric cells achieved a long-term cycling stability of more than 6000 h, and the solid-state Li-S batteries show prolonged cycle life of 700 times accompanied with excellent C-rate properties. By using ultrasound imaging technology, it is proved that the interfacial contact of the integrated solid-state electrolyte/electrode structure is much better than traditional laminated ones. The application of the proposed interfacial self-healing SPEs and the integrated electrodes could be easily extended to mass production of high-performance solid-state batteries.