Highly ionic conductive, self-healable solid polymer electrolyte based on reversibly interlocked macromolecule networks for lithium metal batteries workable at room temperature

Abstract

To maximize the contribution of the amorphous polyethylene oxide (PEO) skeletons to ionic transportation without lowering the chain mobility, reversibly interlocking polymer network (RILN) based solid polymer electrolytes (SPEs) were manufactured through topological reorganization of two PEO networks respectively crosslinked by reversible imine bonds and disulfide bonds. The interlocking structure suppressed the formation of crystallites, improved mechanical strength, and enabled the intimately contacted neighboring molecules to move relative to each other within the meshes of the interlaced parent single networks. Besides, the dynamic dissociation/association of the built-in reversible crosslinkages further allowed for segmental motions and intrinsic self-healing. Consequently, the resultant SPEs exhibited superior ionic conductivity (6.97 × 10⁻⁴ S cm⁻¹), a wide electrochemical window (>4.9 V), decent mechanical strength (0.46 MPa) and failure strain (285.8%), and excellent interfacial stability. The assembled Li/LiFePO₄ cell showed a specific discharge capacity of 145.4 mA h g⁻¹ (0.1C, 25 °C), and a capacity retention of 88.4% after 300 cycles. By taking advantage of healability, the damaged SPEs could be restored as characterized by the regained mechanical strength, ionic conductivity, and cycling performance of the battery. The present work may help in developing a new route to design the SPEs for room temperature lithium-ion batteries.