Highly active catalytic cathode and selective separator for elevated temperature lithium oxygen batteries

Energy plays a vital role in the development of industry and human daily life. Various energy storage technologies have been investigated to meet the demands. Particularly, lithium oxygen battery (LOB) is a uniquely high energy density storage device. Theoretically, LOBs with Li2O2 and Li2O as the discharge products deliver energy densities as high as 3500 Wh kg−1 and 5200 Wh kg−1, respectively. LOB with molten salt electrolyte operating at elevated temperatures is developed which facilitates the reversible 4e−/O2 conversion to achieve Li2O as the discharge product. The molten salt electrolyte relieves the side reactions for the cases with organic solvent in the electrolyte and carbon as the component of the cathode. However, the electrochemical perfor-mance of this LOB still needs optimization. To achieve the high catalytic activity and long-term stability targets, highly active cathode catalyst and effective separator for the LOB operating at elevated temperature are the key enablers. In this work, LaNi0.5Co0.5O3 (LNCO) perovskite was introduced as the LOB cathode catalyst. The physical properties and catalytic activity of LNCO were investigated with different characterization and computational techniques. Moreover, the superior performance of LOB with LNCO cathode operating at 160 °C was demonstrated. A LNCO cathode prepared with a sol-gel method enabled a LOB with an energy efficiency as high as 98.2% and an ultra-low overall overpotential of 50 mV. The preparation of LNCO was further investigated, and a sample prepared with a coprecipitation method with nanostructure effectively reduced the amount of catalyst used to a level as low as 1 mg cm−2 with delivering comparable performance of the LOB. A LOB with a self-supported LNCO@Ni cathode achieved a long-term stability, running for 834 cycles with a 94% capacity retention. The Li2O as discharge product and the corresponding reaction pathways are also confirmed. A metal-organic framework (MOF) based membrane was employed as the separator for the LOB operating at 160 °C. The battery ran stably for over 180 cycles with a coulombic efficiency as high as 99.9%. The membrane not only provided sufficient Li+ transfer rate but also effectively impeded the cross over of discharge product during operation. The LOB with a highly active cathode catalyst and effective separator exhibited good electrochemical performance and stability at elevated temperature. The results also indicate that the LOB operating at elevated temperature is a potential strategy for future development.