Enhancing the Long Cycle Performance of Li-O₂Batteries at High Temperatures Using Metal-Organic Framework-Based Electrolytes

Li-O2 batteries are believed to be practical energy storage devices for electric vehicles due to their ultrahigh theoretical specific energy. The major challenges are the poor interface stability of the electrode/electrolyte caused by the degradation of the electrolyte and cathode and the formation of lithium dendrites, which drain the battery life. Meanwhile, high temperatures will accelerate the interface reaction and lead to the rapid death of batteries. Herein, we present a multifunctional quasi-solid-state electrolyte based on a metal-organic framework (MOF) and an ionic liquid (IL) to simultaneously stabilize the cathode and protect the Li anode in Li-O2 batteries at high temperatures. The electrolyte has negligible volatility and good wettability with the electrodes, and the synergistic effect of the IL and MOF suppresses the lithium dendrite growth by forming a homogeneous Li+ flux. The Li-O2 battery with this electrolyte exhibited a high discharge capacity and improved cycle life (>1100 h) with a low overpotential at 60 °C. Besides, the Li-O2 battery delivered improved electrochemical performances at a higher temperature of 80 °C due to the superior thermal stability of the electrolyte. These results indicate that the quasi-solid-state electrolyte can be a potential strategy for the commercialization of Li-O2 batteries.