Cobalt-decorated carbon nanofibers as a low overpotential cathode for nonaqueous Na-CO2 batteries

Abstract

As the high energy-density energy storage and greenhouse gas capture device, Na-CO2 battery development is impeded by the sluggish CO2 reduction and difficult decomposition of insulating discharge products on the cathode. Here, the cobalt (Co)-decorated carbon nanofibers accompanying with slight Co oxidation were used as the self-standing cathode for Na-CO2 battery. It greatly reduces the discharge overpotential by 500 mV and charge overpotential by 210 mV, delivers a 12 times higher discharge capacity and runs nearly 4 times cycle life than its counterpart. Experiment combined with theory calculation demonstrates that the evenly dispersive, abundant and stable active sites (Co-CoO) with an equal CO2 adsorption-desorption capability is the key to improving cell performance. This work reveals the importance of catalysts/cathodes and provides a direction to design highly efficient catalysts/cathodes for alkali metal-CO2 batteries.