High-Performance Alginate-Poly(ethylene oxide)-Based Solid Polymer Electrolyte.

Solid polymer electrolytes (SPEs) have gained tremendous attention because they are expected to solve the safety problems caused by liquid electrolytes. However, the low ion-transport capacity, insufficient mechanical strength, and unsatisfying flame-retardant properties greatly limit their further application. Here, we designed a poly(ethylene oxide) (PEO)-based SPE by introducing a calcium alginate (CA) nanofiber membrane obtained by electrospinning as a framework. The abundant C═O and -OH groups in the CA macromolecules not only effectively weakened the coordination environment of lithium ions (Li) but also promoted the dissociation of LiTFSI, assisting in the transfer of Li along PEO polymer chains and providing an effective pathway for Li transfer. The introduction of calcium ions (Ca) during the cross-linking process improved the flame-retardant property of the SPE. The obtained SPE exhibited a high ion conductivity (3.86 × 10 S cm, 30 °C), excellent mechanical strength (2.01 MPa), and a wide electrochemical window (5.32 V). The assembled lithium-symmetric battery could undergo stable lithium plating/stripping for 3000 h at 30 °C. Meanwhile, LiFePO (LFP)/Li all-solid-state lithium metal battery showed excellent cycle stability over 300 cycles with a high discharge capacity (141.2 mAh g) and retention rate (92.5%) at 0.3 and 30 °C.