A three-dimensional co-continuous network structure polymer electrolyte with efficient ion transport channels enabling ultralong-life all solid-state lithium metal batteries

Solid polymer electrolytes (SPEs) have emerged as one of the most promising candidates for the construction of solid-state lithium batteries due to their excellent flexibility, scalability, and interface compatibility with electrodes. Herein, a novel all-solid polymer electrolyte (PPLCE) was fabricated by the copolymer network of liquid crystalline monomers and poly(ethylene glycol) dimethacrylate (PEGDMA) acts as a structural frame, combined with poly(ethylene glycol) diglycidyl ether short chain interspersed serving as mobile ion transport entities. The preparaed PPLCEs exhibit excellent mechanical property and outstanding electrochemical performances, which is attributed to their unique three-dimensional co-continuous structure, characterized by a cross-linked semi-interpenetrating network and an ionic liquid phase, resulting in a distinctive nanostructure with short-range order and long-range disorder. Remarkably, the addition of PEGDMA is proved to be critical to the comprehensive performance of the PPLCEs, which effectively modulates the microscopic morphology of polymer networks and improves the mechanical properties as well as cycling stability of the solid electrolyte. When used in a lithium-ion symmetrical battery configuration, the 6 wt%-PPLCE exhibited super stability, sustaining operation for over 2000 h at 30 °C, with minimal and consistent overpotential of 50 mV. The resulting Li|PPLCE|LFP solid-state battery demonstrated high discharge specific capacities of 160.9 mA h g-1 and 120.1 mA h g-1 at current densities of 0.2 C and 1 C, respectively. Even after more than 300 cycles at a current density of 0.2 C, it retained an impressive 73.5% capacity. Moreover, it displayed stable cycling for over 180 cycles at a high current density of 0.5 C. The super cycle stability may promote the application for ultralong-life all solid-state lithium metal batteries.