Electrochemical Performance of B‐Type Vanadium Dioxide as a Sodium‐Ion Battery Cathode: A Combined Experimental and Theoretical Study

Abstract B‐type vanadium dioxide is a frequently investigated lithium‐ion battery material because of its appreciable gravimetric capacity, energy density, rate capability and cycling stability, but investigations of its performance with sodium working metal are scarce. We present a combined experimental‐theoretical study exploring the underlying mechanism of the electrochemical sodiation of B‐type vanadium dioxide. We find agreement between theoretical and experimental results, which complement each other and map out a detailed mechanistic picture. We are able to identify the sluggish diffusion of sodium ions in the vanadium dioxide host material, especially at low concentrations, as a key obstacle to the utilization of the pristine material as a high‐performance cathode for sodium‐ion batteries. Our findings provide context for previously reported results and can be used for a more targeted vanadium dioxide electrode design in the future.