Hybrid poly-ether/carbonate ester electrolyte engineering enables high oxidative stability for quasi-solid-state lithium metal batteries

Building safe and high-energy-density lithium metal batteries (LMBs) is currently being pursued to sustain our modern lifestyles. However, new electrolyte engineering is rigorously required that is capable of simultaneously providing good protection on lithium metal anode and sustaining high oxidative stability at the cathode, besides sufficient bulk conductivity and low interfacial resistance. Here, we report a novel hybrid poly-ether/carbonate ester quasi-solid-state electrolyte with high oxidative stability formed by a simple and efficient in situ polymerization of strategy, in which ring-opening polymerization of ether-based 1,3-dioxolane (DOL) and ester-based ethylene carbonate (EC)-ethylmethyl carbonate (EMC) is initiated by rare-earth triflate catalyst Sc(OTf)3 at room temperature. Such electrolyte engineering not only achieves a sufficiently high ionic conductivity of 5 × 10−4 S cm−1 but enables a high anodic voltage limit of 5 V while maintaining feasible battery manufacture technology. The hybrid poly-DOL/EC/EMC quasi-solid-state electrolyte is capable of producing a stable solid electrolyte interphase (SEI) featuring Li plating/stripping over 500 h at 0.5 mA cm−2 and decreased charge transfer resistance. The derived Li||LiFePO4 quasi-solid-state LMB, benefited from the enhanced oxidative stability of electrolyte, exhibits a notable capacity of 169 mAh g−1 at 1C with no capacity decay after 300 cycles.