Vanadium nitride nanoparticles embedded in carbon matrix with pseudocapacitive behavior for high performance lithium-ion capacitors

Lithium-ion capacitors (LICs) have attracted wide attention due to their potential of achieving merits of high-power output as well as high energy density. However, the key issue of kinetics mismatch between anode and cathode hinders the electrochemical performance of LICs. Therefore, a vanadium nitride composite with nanoparticles embedded in carbon matrix (VN-C) was prepared as an efficiently pseudocapacitive anode material with high electronic conductivity and fast Li-ion diffusion rate. The VN-C composites were synthesized through one-step ammonia heating treatment at different temperatures among which the sample annealed at 600 °C exhibits high specific capacity (513 mAh·g−1 at 0.1 A·g−1), outstanding rate performance (~ 300 mAh·g−1 at 10 A·g−1), and excellent cyclic steadiness (negligible capacity decay over 2000 cycles) in half-cell devices. A high-performance lithium-ion capacitor device was also fabricated by using VN-C-600 as the anode and activated carbon as the cathode, delivering a maximum energy density of 112.6 Wh·kg−1 and an extreme power density of 10 kW·kg−1.