A crosslinked polycarbonate-based hybrid electrolyte enhanced by covalent bonding-driven MOF for dendrite-free solid-state lithium metal batteries

In-situ synthesizing composite polymer electrolytes (CPEs) in high-voltage Li-metal batteries is a promising strategy for achieving high energy density and safety. However, CPEs encounter several challenges, including limited ion migration ability, inferior electrochemical stability, and poor mechanical strength against lithium dendrites, which is caused by poor compatibility of organic–inorganic interface. Herein, we prepared an organic–inorganic hybrid polycarbonate-based solid-state electrolyte (denoted as PVM@PVZs) with a cross-linked structure using bis-acrylamide-based crosslinker and covalent bonding-driven V-ZIF-67 obtained by vinyl-functionalizing Metal Organic Framework (MOF). The prepared V-ZIF-67 is evenly dispersed on the surface of PVDF-HFP fibers via the Electrospinning & Electrospraying technique to improve the interfacial compatibility and help build continuous ion transport channels in the polymer matrix. Meanwhile, the presence of rich Lewis acidic sites and high specific surface area (1162.72 m 2  g −1 ) of V-ZIF-67 efficiently restricts the movement of anions to facilitate lithium-ion transport. These factors enable the optimal hybrid electrolyte (PVM@PVZ-3 containing 20 wt% of V-ZIF-67) to demonstrate high ionic conductivity (7.23 × 10 −4  S cm −1 at 25 °C) and high lithium-ion transference number (0.68). The introduction of covalent bonding and bis-acrylamide-based crosslinker provides sufficient electrochemical stability and mechanical strength for PVM@PVZ-3 to have a wide electrochemical window (5.27 V) and good Li dendrite suppression. Therefore, Li||Li symmetric cell can be stably cycled for 2400 h at a current density of 0.1 mA cm −2 , and the LiFePO 4 ||Li and LiNi 0.8 Co 0.1 Mn 0.1 O 2 ||Li full cells have excellent cycling performance, demonstrating a great prospect of the hybrid electrolyte for practical application in solid-state, high-voltage Li-metal batteries.