Multiple-crosslinking-reinforced ionogel electrolytes for safe and high-performance quasi-solid-state lithium metal batteries

Abstract

Quasi-solid polymer electrolytes (QSPEs) are promising electrolytes for next-generation high-energy-density lithium metal batteries, benefiting from their flexibility and intimate interfacial contact with electrodes. However, conventional QSPEs encounter challenges such as limited Li⁺ mobility and poor mechanical properties. Herein, we design a multiple-crosslinked ionogel electrolyte, featuring a high Li⁺ transference number of 0.74, superior stability against oxidation up to 4.8 V, and high mechanical strength (0.8 MPa) simultaneously. The ionogel electrolyte constructs rapid Li⁺ conductive pathways and promotes the formation of lithium fluoride (LiF), lithium nitride (Li₃N), and lithium sulfide (Li₂S)-enriched passivation layers during Li deposition, greatly enhancing the reversibility of lithium metal deposition. Consequently, the Li‖Li cell demonstrates superior lithium plating/stripping stability for 5000 h, and the Li‖LiFePO₄ cell shows stable cycling performance with 80% capacity retention after 1000 cycles at a rate of 0.5C. Remarkably, the high-voltage Li‖NCM532 cell maintains about 76% of its capacity over 200 cycles at 4.2 V.