Investigating the effect of the textural properties of zeolite-templated carbon air electrode on lithium-oxygen battery performance

The performance of zeolite-templated carbons (ZTCs) as air electrodes in lithium-oxygen battery was investigated, focusing on the role of their porous structure on the formation and decomposition of Li₂O₂ discharge products. Two ZTCs with different mesopore sizes were prepared and extensively characterized. Both ZTC (conventional) and HZTC (House-of-cards) demonstrated significant specific capacities of 4012 mA-h g⁻¹ and 3954 mA-h g⁻¹, respectively, at a current density of 100 mA g⁻¹. However, HZTC exhibited enhanced cycling stability and a notable improvement in both discharge and charge overpotentials, with values of -0.43 V and 0.51 V, compared to -0.74 V and 0.90 V for ZTC. The oxygen reduction reaction interface for both ZTC and HZTC changed from electrode/electrolyte to Li₂O₂/electrolyte as the discharge progressed and the charge transport resistance through the deposited Li₂O₂ particles was significantly reduced in HZTC (132.4 Ω) compared to ZTC (367.2 Ω) at a 40 % state of charge. This enhancement is attributed to the larger mesopores of HZTC, which facilitate the formation of smaller and less crystalline discharge products. In addition, the batteries' poor rechargeability was primarily attributed to the irreversible discharge products formation. These findings underscore the critical impact of carbon porosity on optimizing air electrode performance and offer a pathway for designing high efficiency Li-O₂ batteries with improved performance and extended cycle life.