Lithium–air batteries have long been touted as the next big breakthrough in energy storage, with the potential to surpass conventional lithium-ion batteries in terms of energy storage capacity. However, despite their theoretical advantages, practical applications of these batteries have been limited by issues such as short lifespan and low performance values.
A recent study conducted by a team of researchers from China may have found a solution to these challenges. By introducing a soluble catalyst into the electrolyte of lithium–air batteries, the team was able to improve the batteries’ performance and lifespan significantly.
In traditional lithium-ion batteries, lithium ions move back and forth between two electrodes. In contrast, lithium–air batteries use a metallic lithium anode and a porous cathode with air flowing through it. As the battery is discharged, lithium ions dissolve and move to the cathode, where they react with oxygen to form lithium peroxide. Upon charging, the oxygen is released, and the lithium ions are reduced back to metallic lithium.
One of the main issues with lithium–air batteries is the phenomenon of overpotential, which slows down the electrochemical reactions. The formation and decomposition of lithium peroxide are slow processes, and the conductivity of the compound is low. Additionally, the pores of the cathode can become clogged, and the high potential required for the formation of oxygen can lead to the decomposition of the electrolyte and unwanted side reactions.
The team led by Zhong-Shuai Wu and Xiangkun Ma proposed the addition of a novel imidazole iodide salt to the electrolyte to act as a catalyst and redox mediator. The iodide ions in the salt can easily react to transfer electrons to oxygen, accelerating the reactions and reducing the overpotential of the cathode. The DMI+ ions from the salt can effectively capture lithium ions during discharge and transfer them to the oxygen at the cathode. Additionally, the DMI+ ions form a stable interface film on the anode, preventing direct contact between the electrolyte and the lithium surface.
The team’s electrochemical test cells showed promising results, with low overpotential, high cycle stability, and reversible formation/decomposition of lithium peroxide with no side reactions. This breakthrough could pave the way for the commercialization of lithium–air batteries and help to usher in a new era of high-performance energy storage solutions.
