Pseudocapacitive Vanadium Nitride Quantum Dots Modified One-Dimensional Carbon Cages Enable Highly Kinetics-Compatible Sodium Ion Capacitors

Abstract

The kinetics incompatibility between battery-type anode and capacitive-type cathode for sodium ion hybrid capacitors (SIHCs) seriously hinders their overall performance output. Herein, we construct a SIHCs device by coupling with quantum grade vanadium nitride (VN) nanodots anchored in one-dimensional N/F co-doped carbon nanofiber cages hybrids (VNQDs@PCNFs-N/F) as the freestanding anode and the corresponding activated N/F co-doped carbon nanofiber cages (APCNFs-N/F) as cathode. The strong coupling of VN quantum dots with N/F co-doped 1D conductive carbon cages effectively facilitates the ion/electron transport and intercalation–conversion–deintercalation reactions, ensuring fast sodium storage to surmount aforesaid kinetics incompatibility. Additionally, density functional theory calculations cogently manifest that the abundant active sites in the VNQDs@PCNFs-N/F configuration boost the Na+ adsorption/reaction activity well which will promote both “intrinsic” and “extrinsic” pseudocapacitance and further improve anode kinetics. Consequently, the assembled SIHCs device can achieve high energy densities of 157.1 and 95.0 Wh kg–1 at power densities of 198.8 and 9100.5 W kg–1, respectively, with an ultralong cycling life over 8000 cycles. This work further verified the feasibility of kinetics-compatible electrode design strategy toward metal ion hybrid capacitors.

A multi-chromic supercapacitor of high coloration efficiency integrating a MOF-derived V2O5electrode

“…Similar to the V 2 O 5 electrodes, the charge-discharge profiles in this case are also non-linear, which points towards the presence of surface-controlled faradaic processes. The areal capacitance values for PANI films were also extracted from CV curves according to eqn (5). The highest value obtained was 12.3 mF cm −2 at a scan rate of 10 mV s −1 .…”

“…to ameliorate the quality of life. [3][4][5][6] Electrochemical capacitors or supercapacitors (SCs) have gained widespread attention due to their fast charge-discharge rate and long life along with important advantages to meet the urgent demand of high power density. 7,8 With the recent evolution of electronic devices, the applications of SCs have been extended to multi-functional and smart devices like self-charging SCs, 9 flexible and wearable SCs, 10 shape-memory SCs, 11 thermoresponsive SCs, 12 self-healable SCs, 13 electrochromic SCs (ECSCs), 14,15 etc.…”

High‐rate sodium‐ion storage of vanadium nitride via surface‐redox pseudocapacitance

“…For all the VN materials reported to date, the cyclic voltammetry (CV) curves exhibit a rectangular shape indicating capacitive storage with no evidence of pronounced redox peaks. [ 23–31 ] The energy storage mechanism, however, does not seem to be due to double‐layer capacitance as the magnitude of energy storage shows a significant variation with sweep rate and the area‐normalized capacitance is always much greater than the 20–30 μF cm −2 which is the typical value for double‐layer storage in carbon‐based electrodes. [ 13,32 ]…”

“…Among the various transition metal nitrides, VN has received the most interest and some very impressive energy storage results have been reported. [22][23][24][25][26][27][28][29] However, the mechanism of charge storage in VN and other nitrides is not well understood. For all the VN materials reported to date, the cyclic voltammetry (CV) curves exhibit a rectangular shape indicating capacitive storage with no evidence of pronounced redox peaks.…”

Biomass-derived carbon sponges for use as sodium-ion capacitor electrodes

“…Indeed, much research is now being devoted to the design of negative electrode materials with improved power characteristics that could help mitigate the kinetic imbalance between the two electrodes. [5][6][7] Disordered carbon materials, particularly non-graphitizable or hard carbons with large mean interlayer spacings (d > 0.36 nm), are able to store sodium cations reversibly within their structural defects and pores, reaching sodium capacities greater than 300 mA h g −1 at low current densities. These features have established them as the best option for NIC negative electrodes.…”