In situ fabricated photo-electro-catalytic hybrid cathode for light-assisted lithium–CO2 batteries

Abstract

Severe polarization triggered by the limited electrochemical activity of carbon dioxide as well as the insulating and insoluble discharge product Li₂CO₃ significantly impedes the practical application of Li–CO₂ batteries. Herein, a light-assisted Li–CO₂ system employing SiC/RGO as the photo-electro-catalytic hybrid cathode is presented to overcome the obstacle of polarization in conventional Li–CO₂ cells. RGO is capable of transferring high-energy electrons generated on SiC after absorbing photons, inhibiting the recombination of photogenerated electrons. During the discharge process, the kinetics of CO₂ reduction reaction is promoted by the photogenerated electrons. Thus, the discharge voltage of the battery is increased to 2.77 V, which is very close to the theoretical potential for 4Li + 3CO₂ → 2Li₂CO₃ + C (2.80 V). Besides, the holes generated on the photoelectrode upon charging promote the decomposition of Li₂CO₃, effectively alleviating the overpotential of the Li–CO₂ battery. Consequently, the system exhibits an excellent energy efficiency of 84.4%. These findings demonstrate the promising potential of the photo-assisted electrochemical process in addressing the overpotential issue of Li–CO₂ batteries.