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.

Keywords: Co2MnOx nanowires; Na2CO3 decomposition; Na−CO2 batteries; catalyst screening; freestanding structure.