Bimodal Mesoporous Titanium Nitride/Carbon Microfibers as Efficient and Stable Electrocatalysts for Li–O_2 Batteries

Abstract

The rechargeable Li–O_2 battery has been considered as a sustainable chemical power source for electric vehicles and grid energy storage systems due to the high theoretical specific energy (∼3500 Wh/kg). The practical performance of Li–O_2 batteries is, however, still far below expectations. This is mainly attributed to the (1) intrinsic sluggish reaction kinetics of the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), (2) passivation of the electrodes by electrical isolation and pore blocking, and (3) chemical instability of the organic cell components, i.e., electrolyte, polymer binder, and carbon electrode, in the presence of O_2•– and Li_2O_2. It is crucial to develop highly porous, three-dimensional, conducting cathode catalyst/gas diffusion layer (GDL) architectures possessing superior catalytic activity and stability with respect to the ORR and the OER in order to address these issues. All of these requirements prompted us to examine the catalytic performance of porous framework metal nitride electrodes for Li–O_2 batteries.