Cobalt/Nitrogen Co-Doped Carbon Materials Enhance the Reaction Rate of Sodium-Potassium Alloy Electrodes.

Abstract

Sodium-potassium (NaK) alloy electrodes are ideal for next-generation dendrite-free alkali metal electrodes due to their dendrite-free nature. However, issues such as slow diffusion kinetics due to the large K+ radius and the loss of active potassium during the reaction severely limit its application. Here a novel cobalt/nitrogen-doped carbon material is designed and it is applied to the construction of a NaK alloy electrode. The experimental and theoretical results indicate that the confining effect of the nitrogen-doped graphitic carbon layer can protect the cobalt nanoparticles from corrosion leaching, while the presence of Co─Nx bonds and cobalt nanoparticles provides more active sites for the reaction, realizing the synergistic effect of adsorption-catalytic modulation, lowering the K+ diffusion energy barrier and promoting charge transfer and ion diffusion. The application of this electrode to a symmetrical battery can achieve more than 1800 stable cycles under a current density of 0.4mA cm-2 and a charge/discharge specific capacity of 122.64 mAh g-1 under a current of 0.5C in a full battery. This finding provides a new idea to realize a fast, stable, and efficient application of NaK alloy electrodes.