Unlocking recent progress in niobium and vanadium carbide-based MXenes for sodium-ion batteries

The performance of electrochemical energy storage (EES) devices is determined by the inherent characteristics of electrode materials such as anodes and cathodes. 2D materials are increasingly being studied for their unique structural and electrochemical properties. Various materials, including transition metal oxides, metal sulfides, phosphides, and metal-organic framework (MOF) compounds, have been explored as potential anodes for sodium storage. However, challenges include significant volume and conductivity changes, cyclability, low capacity, and hindered overall rate performance in sodium-ion batteries (SIBs). Employing 2D-layered transition metal carbides and nitrides (MXenes) and their functionalized/surface-modified composites provides a promising strategy for minimizing volume expansion during charge-discharge, mass-transport properties, and enhancing conductivity, thereby improving the specific capacity, rate capability, and cycling stability of SIBs. This review examines the ability of two specific MXene compounds, namely niobium carbide (Nb-C) and vanadium carbide (VC), to be advanced electrode materials for enhancing the performance of SIBs. Furthermore, it comprehensively analyses recent developments in SIB anodes based on Nb-C and VC hybrid materials, shedding light on their electrochemical and structural properties. Last, the crucial challenges of Nb-C and VC electrodes employed in SIBs are explained, and future insights into the SIB application of these electrodes are elaborated.