Modulating the Configuration of Air Cathodes toward the Extended Triple-Phase Boundaries of Li-O2 Batteries

Abstract

Li-O₂ batteries (LOBs), with their high theoretical energy density, are seen as the prime candidates for post-lithium-ion battery development to address the increasing energy demand. The performance of LOBs is primarily determined by the formation and decomposition behavior of their discharge product, lithium peroxide (Li₂O₂), formed at the triple-phase boundary (TPB) among Li⁺, e^–, and O₂. Traditional electrodes, however, have a limited TPB area, which restricts Li₂O₂ generation and lowers the energy density. In this study, a unique dual-sided electrode configuration, designed to extend the TPB, was suggested. By applying an active material slurry on both sides of the gas diffusion layer, this configuration enhances mass transfer and facilitates the nucleation/decomposition of Li₂O₂. Such improvements lead to increased capacity and better cyclic reversibility, effectively addressing the trade-off between capacity and efficiency. These findings highlight the crucial role of an extended TPB in boosting the reversibility and energy density of LOBs.