A Rotating Cathode with Periodical Changes in Electrolyte Layer Thickness for High‐Rate Li‒O2 Batteries

• Published in: Advanced materials (Weinheim) 2024-08, Vol.36 (31), p.e2403230-n/a
• Main Authors: Liang, Yu‐Long, Yu, Yue, Li, Zi‐Wei, Yang, Dong‐Yue, Liu, Tong, Yan, Jun‐Min, Huang, Gang, Zhang, Xinbo
• Format: Article
• Language: English
• Subjects: Cathodes; Current density; Decoupling; Discharge; Electrochemical cells; Electrolytes; Electrolytic cells; high rate; Li‒O2 batteries; Mass transfer; mass transfers; rotating cathodes; Rotating liquids; Rotation; Storage batteries; Thickness
• ISSN: 0935-9648; 1521-4095; 1521-4095
• DOI: 10.1002/adma.202403230

Li–O2 batteries (LOBs) possess the highest theoretical gravimetric energy density among all types of secondary batteries, but they are still far from practical applications. The poor rate performance resulting from the slow mass transfer is one of the primary obstacles in LOBs. To solve this issue, a rotating cathode with periodic changes in the electrolyte layer thickness is designed, decoupling the maximum transfer rate of Li+ and O2. During rotation, the thinner electrolyte layer on the cathode facilitates the O2 transfer, and the thicker electrolyte layer enhances the Li+ transfer. As a result, the rotating cathode enables the LOBs to undergo 58 cycles at 2.5 mA cm−2 and discharge stably even at a high current density of 7.5 mA cm−2. Besides, it also makes the batteries exhibit a large discharge capacity of 6.8 mAh cm−2, and the capacity decay is much slower with increasing current density. Notably, this rotating electrode holds great promise for utilization in other electrochemical cells involving gas‐liquid‐solid triple‐phase interfaces, suggesting a viable approach to enhance the mass transfer in such systems. It is generally believed that the rate performance of Li‒O2 batteries (LOBs) is limited by the slow mass transfer. To this end, a new type of LOB with a rotating cathode has been designed to decouple the maximum transfer rate of Li+ and O2, and consequently, the rate performance of LOBs has been significantly improved.