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CsI as Multifunctional Redox Mediator for Enhanced Li–Air Batteries

Lee, Chan Kyu, Park, Yong Joon
ACS Applied Materials & Interfaces 2016 v.8 no.13 pp. 8561-8567
air, anodes, batteries, carbon, cesium, electrolytes, ions
We introduce CsI as a multifunctional redox mediator to enhance the performance of Li–air batteries. CsI dissolved in the electrolyte is ionized into Cs⁺ and I–, which perform their roles in the Li anode and air electrode, respectively. The I– ions in the electrolyte facilitate the dissolution of Li₂O₂ in the air electrode as a redox mediator, which reduces the overpotential of the cell. The low overpotential also leads to the suppression of parasitic reactions occurring in the high-voltage range, such as the decomposition of the electrolyte and the reaction between Li₂O₂ and carbon. At the same time, the Cs⁺ ions act as an electrostatic shield at the sharp points of the Li anode, hindering the growth of Li dendrite. The combined effects of reduced parasitic reactions and hindered Li-dendrite growth successfully improve the cyclic performance of Li–air cells.