Molybdenum Nitride Nanocrystals Anchored on Phosphorus-Incorporated Carbon Fabric as a Negative Electrode for High-Performance Asymmetric Pseudocapacitor.

Pseudocapacitors hold great promise to provide high energy-storing capacity; however, their capacitances are still far below their theoretical values and they deliver much lower power than the traditional electric double-layer capacitors due to poor ionic accessibility. Here, we have engineered MoN nanoparticles as pseudocapacitive material on phosphorus-incorporated carbon fabric with enhanced ionic affinity and thermodynamic stability. This nanocomposite boosts surface redox kinetics, leading to pseudocapacitance of 400 mF/cm (2-fold higher than that of molybdenum nitride-based electrodes) with rapid charge-discharge rates. Density functional theory simulations are used to explain the origin of the good performance of MoN@P-CF in proton-based aqueous electrolytes. Finally, an all-pseudocapacitive solid-state asymmetric cell was assembled using MoN@P-CF and RuO (RuO@CF) as negative and positive electrodes, respectively, which delivered good energy density with low relaxation time constant (τ) of 13 ms (significantly lower than that of carbon-based supercapacitors).