Garnet electrolyte-based integrated architecture for high-performance all-solid-state lithium-oxygen batteries

All-solid-state lithium-oxygen (Li-O₂) battery is considered to be a promising next-generation energy storage system to address the issues related to low specific capacity, unsafety and unstable electrochemistry that exist in conventional liquid Li-O₂ batteries. However, current solid-state Li-O₂ batteries still encounter the challenge of high impedance at the electrode/electrolyte interface. In addition, the deficiency of triple-phase boundaries (containing Li⁺, e⁻ and O₂) limits the active sites for electrochemical reaction in the battery cathode. Herein, an integrated architecture based on a garnet electrolyte Li_6.4La₃Zr_1.4Ta_0.6O₁₂ (LLZTO) and a porous composite cathode for high-performance all-solid-state Li-O₂ batteries is developed. The unique internal structure effectively reduces the interfacial impedance of the battery, provides a large number of active sites at triple-phase boundaries and increases the electrochemical stability. As a result, the obtained batteries can deliver a superior high full discharge capacity of 13.04 mA h cm⁻² and an excellent cyclic performance (86 cycles). In addition, X-ray photoelectron spectroscopy, differential electrochemical mass spectrometry and theoretical calculations further demonstrate the effectiveness of this design in enhancing the interfacial performance, electrochemical performance, and stability of the battery. This study is thus expected to facilitate practical applications for truly all-solid-state Li-O₂ batteries, and even for other systems of metal-oxygen (air) batteries.