• Chodankar, Nilesh
• Qiao, Shi Zhang

Abstract

<p>Owing to the excellent physical properties of metal nitrides such as metallic conductivity and pseudocapacitance, they have recently attracted much attention as competitive materials for high-performance supercapacitors (SCs). However, the voltage window for metal nitride-based symmetric SCs is limited (0.6–0.8 V) in aqueous electrolyte due to the oxidation at high negative potentials. In this respect, ultra-small tungsten nitride particles onto the phosphorous modified carbon fabric (W₂N@P-CF) are engineered as a promising hybrid electrode for pseudocapacitors. Additionally, the fact that the W₂N@P-CF electrode can operate in the negative potential region is exploited to design asymmetric pseudocapacitors by coupling with a polypyrrole on carbon fabric (PPy@CF) as the positive electrode. Remarkably, the W₂N@P-CF//PPy@CF asymmetric cell can be cycled in a wide voltage window of 1.6 V that is almost two times higher than that of metal nitrides symmetric SCs. The pseudocapacitive behavior with matching different potential regions of W₂N@P-CF and PPy@CF, considerably enhance performance of asymmetric device. The device delivers high volumetric capacity (7.1 F cm⁻³), high energy (2.54 mWh cm⁻³), power densities, and good cycling stability (88%) over 20 000 cycles. Thus, pseudocapacitive metal nitride-based devices hold a great promise to provide high voltage and improved energy density in aqueous electrolyte.</p>

Topics

• density
• impedance spectroscopy
• Carbon
• energy density
• nitride
• tungsten