Enhancing Catalyzed Decomposition of Na2CO3 with Co2MnO x Nanowire-Decorated Carbon Fibers for Advanced Na-CO2 Batteries.

Abstract

The metal-CO2 batteries, especially Na-CO2, batteries come into sight owing to their high energy density, ability for CO2 capture, and the abundance of sodium resource. Besides the sluggish electrochemical reactions at the gas cathodes and the instability of the electrolyte at a high voltage, the final discharge product Na2CO3 is a solid and poor conductor of electricity, which may cause the high overpotential and poor cycle performance for the Na-CO2 batteries. The promotion of decomposition of Na2CO3 should be an efficient strategy to enhance the electrochemical performance. Here, we design a facile Na2CO3 activation experiment to screen the efficient cathode catalyst for the Na-CO2 batteries. It is found that the Co2MnO x nanowire-decorated carbon fibers (CMO@CF) can promote the Na2CO3 decomposition at the lowest voltage among all these metal oxide-decorated carbon fiber structures. After assembling the Na-CO2 batteries, the electrodes based on CMO@CF show lower overpotential and better cycling performance compared with the electrodes based on pristine carbon fibers and other metal oxide-modified carbon fibers. We believe this catalyst screening method and the freestanding structure of the CMO@CF electrode may provide an important reference for the development of advanced Na-CO2 batteries.