Fast and Reversible Surface Redox Reaction in Nanocrystalline Vanadium Nitride Supercapacitors

Abstract

Modification of the surface chemistry of nanocrystalline VN yields a new class of supercapacitors that deliver an impressive specific capacitance. The creation of surface nanolayers of VOx (poor electronic conductivity) on the electronically conductive nanocrystalline VN shown in the figure and on the cover gives rise to a series of reversible redox reactions that are thought to be responsible for the high capacitance. Application of the concept to other transition metals is expected to broaden the scope of supercapacitor materials.

Solvothermal synthesis and electrochemical charge storage assessment of Mn3N2

“…10,11 Mn3N2 was found to be highly unstable in acidic electrolytes so testing focussed on the electrochemistry in KOH solution. Titanium foils were used as the current collector as the foils themselves had very low capacitance (~0.1 F) and did not develop any new features on extended cycling in the electrolytes used.…”

“…MnO2 can deliver capacitances of ~240 F g -1 , although this is over a relatively narrow potential range and is subject to some fading during cycling. 15 An oxide surface can develop during cycling of metal nitride electrodes 11 and this prompted our interest in making nanoparticulate manganese nitrides.…”

“…6,8 Metal nitrides are a current research focus as electrode materials for electrochemical capacitors due to a number of studies that have shown useful capacities on TiN, VN and MoN. 9,10,11,12 The current redox capacitor material of choice is RuO2, which can deliver capacities of around 720 F g -1 but is too costly and toxic for widespread use. 13 A number of other oxides have also been used, but the current interest in nitrides comes from the possibility of producing materials with a high electronic conductivity nitride core and an oxide coating with a high surface area.…”

Ab Initio Molecular Dynamics Simulations of Nitrogen/VN(001) Surface Reactions: Vacancy-Catalyzed N2 Dissociative Chemisorption, N Adatom Migration, and N2 Desorption

“…46,47 Moreover, supercapacitors based upon VN deliver remarkable specific capacitance with high energy and high power densities, the properties required for developing efficient energy-storage devices. 48 VN and VN-based nanostructures are also promising anode materials for rechargeable lithium batteries. 49,50 Recently, NaCl-structure (cubic-B1) VN(001) has been identified as a novel electrode material for the synthesis of ammonia at room temperature and atmospheric pressure, a requirement for sustainable production of inorganic fertilizers.…”

Facile Synthesis of Co3O4/Mildly Oxidized Multiwalled Carbon Nanotubes/Reduced Mildly Oxidized Graphene Oxide Ternary Composite as the Material for Supercapacitors

“…Their electrode materials generally involve various metal oxides [18][19][20][21][22] and conductive polymers. [23][24][25][26][27][28][29][30] In recent years, transition metal oxides have been drawn extensive research attentions for pseudo-capacitors since they could provide higher capacitance than carbon materials and longer cycling life than conductive polymers. [31][32][33] Among these materials, Co 3 O 4 shows an inviting prospect because of its ultra-high theoretical specific capacitance of 3560 F g −1…”