The effects of oxygen pressure on the discharge performance of potassium–oxygen batteries. Issue 8 (21st March 2022)

• Record Type: Journal Article
• Authors: Küpper, Jannis; Simon, Ulrich
• Is Part Of: Sustainable energy & fuels. Volume 6:Issue 8(2022)
• Page Start: 1992
• Page End: 2000
• Publication Date: 2022-03-21
• Subjects: Renewable energy sources -- Periodicals; Fuel cells -- Periodicals; Electric batteries -- Periodicals; Electrochemistry -- Periodicals; 660.297
• DOI: 10.1039/d2se00182a
• Languages: English
• ISSNs: 2398-4902

Abstract

Abstract : Applying high oxygen pressure drastically improves the discharge performance of potassium-oxygen batteries. High oxygen pressure can also prevent parasitic reactions leading towards K2 SO4 and K2 CO3 induced by oxygen depletion within the cathode. Abstract : The potassium–oxygen battery (KOB) has distinguished itself from other metal–oxygen batteries by its facile cell chemistry that enables thousands of cycles with negligible performance loss. Recently, the main discharge product KO2 was reported to undergo a reduction towards K2 O2 in the absence of oxygen, which was identified as the cause of diminished rechargeability. This raises the question how oxygen partial pressure p (O2 ) affects the discharge behavior of KOB. In this study, the influence of p (O2 ) on the discharge performance is assessed between 0.2 atm and 11 atm. The p (O2 )-dependent cell failure mechanisms are investigated by post mortem analysis of the discharge product formed on a carbon cathode. Low p (O2 ) results in insufficient oxygen transport throughout the cathode leading to low rate capability and capacity. In addition, we find that oxygen depletion promotes parasitic reactions involving the electrolyte solvent dimethyl sulfoxide. High p (O2 ) is identified as an effective approach towards preventing oxygen depletion and subsequent side reactions. Furthermore, high p (O2 ) also drastically improves the discharge performance by enabling more efficient cathode utilization. These findings suggest that a high-pressure supply of pure oxygen will be advantageous to further increase cell performance of KOB and thus open avenues for yet unexplored applications.