High-performance all-solid-state polymer electrolyte with fast conductivity pathway formed by hierarchical structure polyamide 6 nanofiber for lithium metal battery

Abstract The utilization of all-solid-state electrolytes is considered to be an effective way to enhance the safety performance of lithium metal batteries. However, the low ionic conductivity and poor interface compatibility greatly restrict the development of all-solid-state battery. In this study, a composite electrolyte combining the electrospun polyamide 6 (PA6) nanofiber membrane with hierarchical structure and the polyethylene oxide (PEO) polymer is investigated. The introduction of PA6 nanofiber membrane can effectively reduce the crystallinity of the polymer, so that the ionic conductivity of the electrolyte can be enhanced. Moreover, it is found that the presence of finely branched fibers in the hierarchical structure PA6 membrane allows the polar functional groups (C=O and N−H bonds) to be fully exposed, which provides sufficient functional sites for lithium ion transport and helps to regulate the uniform deposition of lithium metal. Moreover, the hierarchical structure can enhance the mechanical strength (9.2 MPa) of the electrolyte, thereby effectively improving the safety and cycle stability of the battery. The prepared Li/Li symmetric battery can be stably cycled for 1500 h under 0.3 mA cm−2 and 60 °C. This study demonstrates that the prepared electrolyte has excellent application prospects in the next generation all-solid-state lithium metal batteries.