Non-aqueous Li-O2 batteries have been the subject of intense research interest over the past decade or two, owing to their very high theoretical gravimetric energy density; potentially up to three times that of state-of-the-art lithium ion batteries. Despite this widespread effort, lithium oxygen batteries still suffer from a number of significant issues, including high overpotential on charge and poor cycle life. Part of this poor charging performance can be attributed to the insulating nature of the Li2O2 formed on discharge, which makes direct electrochemical oxidation challenging. While a number of approaches have been taken to try and catalyze the charging process of a Li-O2 battery, soluble lithium halides, such as lithium iodide and lithium bromide, in particular, have shown very promising performance. Despite this promise, there has been serious ambiguities in literature relating to the influence of lithium iodide on both the discharge and charge processes. In this talk, strategies for controlling the thermodynamics of the chemical oxidation of Li2O2 during the charging progress are discussed, based on controlling solvation energy and through the formation of halide-complexes. This work demonstrates that the charging process of a Li-O2 battery can be optimized for both energy efficiency and effective oxidation of Li2O2 through systematic electrolyte design.

Catalyzing the charging process in Li-O2 batteries using lithium halides

256th National Meeting (2018)

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