Solid-State Li-O2 Battery Using a Perovskite Type Solid Electrolyte with an Improved Interfacial Property

Theoretically Li–O2 batteries can release an energy density of 11 680 W h kg-1 comparable to that of gasoline (13 000 W h kg-1) by integrating the metal lithium with readily available ambient oxygen as an active material for cathode. Even based on the entire battery system, the capacity of ~1000 W h kg-1 is still several times higher than that of Li-ion batteries. Thus, Li–O2 batteries have attracted significant attention as a possible green alternative to current lithium-ion batteries for electric vehicles. Though Li-O2 batteries have promising performance, several issues still exist in its practical operation. One major issue is the use of liquid electrolytes, which causes several problems including evaporation, leakage, flammability, low oxygen solubility and diffusion, and chemical and/or electrochemical instabilities. The use of a solid-state electrolyte can be alleviated this issue. In addition, the solid-state electrolyte can significantly improve the stability of Li–O2 batteries for long-term operation by shielding the Li anode from oxygen, CO2, and moisture in the air. The solid-state electrolyte can also protect short circuiting caused by Li dendrites during long term operation. In our study, we propose and fabricate a novel solid-state Li-O2 cell composed of a Li metal as an anode, Al2O3 as an interlayer, a perovskite-structured Al-doped Li-La-Ti-O (A-LLTO) as solid electrolyte, and a solid electrolyte integrated cathode frame covered with a carbon layer and CoO nanoparticles as catalysts for the cyclic oxygen evolution reaction and oxygen reduction reaction. In our research, we used ALD of Al2O3 as an interlayer due to its ability to prevent the direct contact between Li and A-LLTO solid electrolyte to enhance the stability of solid electrolyte against Li anode, and to form a thermodynamically stable Li ion conducting LiAlOx solid electrolyte by reacting with Li that will enhance the Li ion migration. This work demonstrates the importance of interface coupling between Li anode and solid electrolyte on the development of high performance Li−O2 batteries.