Sodium-ion capacitors with unique characteristics such as higher energy density than electrical double-layer capacitors, higher power density than rechargeable batteries, and abundant sodium resources represent current research trend in developing large-scale electrical energy storage technology. One of the key challenges presently facing the development of this technology is the imbalanced kinetics between the sluggish Faradaic sodium insertion in the anode and the fast capacitive ion adsorption on the cathode. Here we demonstrate the sol-gel synthesis of a novel, high-rate, stable composite anode material for sodium-ion capacitors (NICs). The composite consisted of Nb2O5 nanoparticles embedded in a carbon matrix (denoted by m-Nb2O5/C). Sodium-ion capacitors employing the m-Nb2O5/C anode and a commercial activated carbon as the cathode showed an admirable performance, delivering high energy densities in a wide range of power densities (73 Wh kg−1@250 W kg-1 and 16.8 Wh kg−1@20 kW kg−1). These favourable cell characteristics are attributed to the properties of the m-Nb2O5/C anode: the mesoporous structure that facilitates electron and ion transport, the presence of the niobium carbide interlayer between the Nb2O5 nanoparticles and the surrounding graphitic carbon that additionally improves the electron conductivity, and the predominant capacitive charge storage mechanism.