One-Step Solvothermal Preparation of Mn-Doped VO₂(B) Nanosheets for High-Performance Supercapacitors

Abstract

Pure and Mn-doped VO2(B) nanosheets were prepared using a simple one-step solvothermal reaction with V2O5 and H2O2 as precursors with Mn(CH3COO)2·4H2O added directly into the precursor solution to obtain the Mn-doped variant. The powder morphology, local structures and cation oxidation states were investigated using scanning electron microscopy (SEM), powder X-ray diffraction (XRD), high-energy X-ray scattering, X-ray absorption near edge spectroscopy (XANES), and X-ray photoelectron spectroscopy (XPS). The electrochemical properties were studied using cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) and electrochemical impedance spectroscopy (EIS). The Mn-doped VO2(B) nanosheet sample, comprising a mixed phase of two polymorphs of VO2, exhibits 80% higher capacitance at 2 mV s−1 scan rate, 2X smaller charge transfer resistance, and much improved cyclic stability compared with pure VO2(B). The improved electrochemical response is attributed to the enhanced mass transfer kinetics due to slightly differing microstructures and formation of more varied oxidation states of the V and Mn ions such that the charged defects increase the electrical conductivity and charge transfer efficiency.

Understanding the Synergistic Effects and Structural Evolution of Co(OH)2 and Co3O4 toward Boosting Electrochemical Charge Storage

“…Clearly, the Co 3 O 4 / Co(OH) 2 exhibits smaller percentage of diffusion-controlled process compared with pure Co(OH) 2 . Similar results have also been obtained by comparing the b-values obtained from the slope of linear fit of log (i) versus log (v) plot at peak potential for all three samples using the method described by Gao et al [28] Typically, there are two well-defined extremes for the b-value; when b = 0.5, the electrode kinetics are controlled by the diffusion process, while b = 1.0 represents a capacitive process or nondiffusion controlled process. From Figure S17 In general, the structural characterizations and electrochemical analysis clearly show that the presence of a conductive and robust interfacial Co 3 O 4 layer can effectively improves the electrode's rate capability and cycle stability compared with pure Co(OH) 2 without significantly sacrifice its capacity.…”

A high-performance flexible energy storage device from biomass-derived porous carbon supported MnCo2O4 nanorods and MnO2 nanoscales

“…MnO 2 is also a transition metal oxide with multiple valences, a high theoretical C S value ($1109 F g À1 ), high chemical stability, natural abundance, and eco-friendliness. 17,18 Despite having so many advantages, these materials suffer from low ionic and electronic conductivities, low energy densities, agglomeration, and obliteration of morphology throughout the long cycling process. 15,17 These limitations can be overcome by rationally combining the merits of MnCo 2 O 4 and MnO 2 with biomass-derived porous carbon.…”

Polyaniline inside the pores of high surface area mesoporous silicon as composite electrode material for supercapacitors

“…[1][2][3][4][5][6][7][8][9] Typically faradaic pseudocapacitors have further two different types comprising redox pseudocapacitance (surface or near-surface redox reactions) and intercalation pseudocapacitance (electrolyte ions intercalate into the tunnels/layers of the electrode materials accompanied by faradaic charge-transfer with no phase transitions). 10,11 Transition metal oxides and hydroxides, transition metal dichalcogenides and carbon based materials have been studied as electrode materials for charge storage applications. 12 Aer the discovery of graphene, rapid development of other new emerging layered structures such as MXenes, 13 layered nanoclay, phosphorene, bismuthene and 2D graphene analogues have excellent charge storage capabilities.…”