Quasi-Solid-State Rechargeable Li–O₂ Batteries with High Safety and Long Cycle Life at Room Temperature

As interest in electric vehicles and mass energy storage systems continues to grow, Li–O2 batteries are attracting much attention as a candidate for next-generation energy storage systems owing to their high energy density. However, safety problems related to the use of lithium metal anodes have hampered the commercialization of Li–O2 batteries. Herein, we introduced a quasi-solid polymer electrolyte with excellent electrochemical, chemical, and thermal stabilities into Li–O2 batteries. The ion-conducting QSPE was prepared by gelling a polymer network matrix consisting of poly(ethylene glycol) methyl ether methacrylate, methacrylated tannic acid, lithium trifluoromethanesulfonate, and nanofumed silica with a small amount of liquid electrolyte. The quasi-solid-state Li–O2 cell consisted of a lithium powder anode, a quasi-solid polymer electrolyte, and a Pd3Co/multiwalled carbon nanotube cathode, which enhanced the electrochemical performance of the cell. This cell, which exhibited improved safety owing to the suppression of lithium dendrite growth, achieved a lifetime of 125 cycles at room temperature. These results show that the introduction of a quasi-solid electrolyte is a potentially new alternative for the commercialization of solid-state Li–O2 batteries.