Self-healable solid electrolytes based on thiourea H-bonded supramolecular polymers

Polymeric systems that enable lithium transport are promising candidates for next-generation lithium metal batteries. Aiming to develop robust solid polymer electrolytes (SPEs) with high conductivity and mechanical strength, recent approaches have incorporated self-healing polymers into these systems. Here, we present a family of thiourea H-bonded self-healing SPEs, synthesized via a straightforward polycondensation reaction. These SPEs demonstrate excellent thermal stability up to 280 °C, electrochemical stability to 4.2 V, and effective self-healing capabilities. By adjusting the length of the lithium-conducting ethylene oxide spacer, both mechanical strength and conductivity can be finely tuned. Additionally, we observe a distinctive thiourea-anion complex interaction within these SPEs which enhances lithium salt solubility in the poly(thiourea-ether) matrix, significantly boosting ion conductivity. This work provides valuable insights for designing H-bonded self-healing polymer electrolytes with tailored properties for future applications in Li-metal batteries. • Novel self-healing polythiourea solid polymer electrolytes (SPEs) are developed. • Non-linear H-bonding arrays induce good self-healing and suppress crystallization. • Fundamental physico-chemical properties of thiourea-based SPEs are investigated. • A unique thiourea-anion supramolecular interaction is reported. • Thiourea-anion pathways increase salt solubility and boost ionic conductivity.