Study on evolution process and electrochemical behavior of porous cathode in discharge process of the solid-state lithium-oxygen battery

Abstract

Solid-state lithium‑oxygen battery is one of the lithium-metal batteries with high theoretical specific capacity and strong safety. In order to explore the evolution process and electrochemical behavior of the battery, a study of combination of simulation and experiment is conducted in this paper. Firstly, solid-state lithium‑oxygen batteries with quartz tubes as the battery shell are designed for the experiment. FTIR and Raman results show that the lithium peroxide is produced as discharge products and SEM images show the product is accumulated on the surface of carbon particles and bound the carbon particles into blocks during the cathode evolution process. Then, a 1D multi-physics coupling field model referred to the experiment is established to investigate the electrochemical behavior of the battery. The calculated discharge curves are compared with the experimental discharge curves to verify the accuracy of the model. Using the model, the electrochemical behaviors, such as discharge product volume fraction, active three-phase interface, LATP phase potential and carbon phase potential, are analyzed. At last, the reasons for discharge termination are attributed to the accumulation of lithium peroxide and the decline of active three-phase interface.