Invited Presentation: Striving Toward an Ultrahigh Energy Density Li-Air Battery

In the pursuit to develop a practical rechargeable Li/air battery, we have studied the mechanisms of O₂ reduction and evolution reactions (ORR and OER), and the nature of the products formed, in a series of organic electrolytes and ionic liquids. The distinct ORR products formed in these disparate electrolyte solutions can be explained using a general theory based on the Hard Soft Acid Base (HSAB) concept. We have found that the electron donor property of the solvent modulates Li⁺ acidity in organic electrolytes , through the formation of complexes (or solvates)  of the formula Li(solvent)_n⁺ where, n = 2-4, and these solvates in turn influence the mechanisms and products of both catalyzed and uncatalyzed ORR in Li-air batteries.  A cobalt phthalocyanine-derived catalyst has enabled the full reduction of O₂ to Li₂O in selected solvents, and provided improved rechargeability for Li-air cells.   

Acknowledgment: The US Army US Army RDECOM CERDEC C2D, Aberdeen Proving Grounds, MD, provided financial support for this work

Dr. K. M. Abraham is Professor at Northeastern University Center for Renewable Energy Technology, Boston, Massachusetts, USA. KM has made many pioneering contributions to advance primary and secondary lithium and Li-ion batteries including the invention of the lithium-air battery.