Transparent Conducting Oxides as Cathodes in Li–O2 Batteries: A First Principles Computational Investigation

Abstract

Li–O2 batteries have traditionally used carbon-based electrodes (graphite, buckypaper) as the cathode of choice due to their good electrical conductivity, stability against nonaqueous electrolytes like dimethoxyethane, and ease of handling. But, the carbon cathode also leads to the formation of carbonate byproducts that increase overpotentials during charging, leading to degradation of the cathode and reduction of cyclability. Recent investigations have focused on using metal oxides like SnO2, TiO2 as viable cathode alternatives in Li–O2 systems. In this paper, we investigate transparent conducting oxides (TCOs) as cathodes, with focus on the interface between the TCO surfaces and the discharge product, Li2O2, in the Li–O2 battery using first principles computations. We also explore the role dopants can play in achieving a stable electrically conducting cathode that promotes discharge of Li2O2. Our results show that attention must be paid to choosing appropriate surface of these oxides. We extend the analysis to suggest possible oxide chemistries that should be investigated as cathodes in Li–O2 batteries.