Strongly Coupled Pyridine-V2O5•nH2O Nanowires with Intercalation Pseudocapacitance and Stabilized Layer for High Energy Sodium Ion Capacitors

Developing pseudocapacitive cathodes for sodium ion capacitors (SICs) is very significant for enhancing energy density of SICs. Vanadium oxides cathodes with pseudocapacitive behavior are able to offer high capacity. However, the capacity fading caused by the irreversible collapse of layer structure remains a major issue. Herein, based on the Acid-Base Proton theory, a strongly coupled layered pyridine-V2O5 center dot nH(2)O nanowires cathode is reported for highly efficient sodium ion storage. By density functional theory calculations, in situ X-ray diffraction, and ex situ Fourier-transform infrared spectroscopy, a strong interaction between protonated pyridine and V. O group is confirmed and stable during cycling. The pyridineV(2)O(5)center dot nH(2)O nanowires deliver long-term cyclability (over 3000 cycles), large pseudocapacitive behavior (78% capacitive contribution at 1 mV s(-1)) and outstanding rate capability. The assembled pyridine-V2O5 center dot nH(2)O//graphitic mesocarbon microbead SIC delivers high energy density of approximate to 96 Wh kg(-1) (at 59 W kg(-1)) and power density of 14 kW kg(-1) (at 37.5 Wh kg(-1)). The present work highlights the strategy of realizing strong interaction in the interlayer of V2O5 center dot nH(2)O to enhance the electrochemical performance of vanadium oxides cathodes. The strategy could be extended for improving the electrochemical performance of other layered materials.