Hausmannite Manganese oxide cathodes for supercapacitors: Surface Wettability and Electrochemical Properties (original) (raw)
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MDPI, 2023
This investigation is motivated by the need in the development of manganese oxide cathodes for supercapacitors with high capacitance at high charge–discharge rates and enhanced capacitance retention in a wide range of charge–discharge rates. It also addresses the challenge of eliminating the time-consuming activation procedure, which limits the applications of Mn3O4 cathodes. The new approach is based on the use of environmentally friendly and biocompatible pH modifiers–dispersants, such as polyethylenimine (PEI) and meglumine (MG) for hydrothermal synthesis. In this approach, the use of inorganic alkalis is avoided. We demonstrate the benefits of this approach for the fabrication of manganese oxide nanoparticles, such as Mn-PEI and Mn-MG. Electrodes with a high active mass of 40 mg cm−2 are fabricated and electrochemically tested in 0.5 M Na2SO4 electrolyte. The method of electrode material fabrication offers benefits for the accelerated electrode activation procedure, which is practically eliminated for Mn-MG electrodes. The Mn-MG electrodes showed a remarkably high capacitance of 3.68 F cm−2 (93.19 F g−1) at a sweep rate of 100 mV s−1 and a high capacitance retention of 90.6% in the CV sweep range of 1–100 mV s−1.
Electrophoretically deposited manganese oxide coatings for supercapacitor application
Ceramics International, 2009
In the present study, manganese oxide electrodes with promising pseudo-capacitive properties were prepared by electrophoretic deposition (EPD) using needle-like manganese dioxide powders. As-deposited coating exhibited a porous microstructure where the size and shape of the starting powders can be observed. The electrochemical performance of the as-deposited coating was then evaluated by cyclic voltammetry (CV) up to 300 times. The initial specific capacitance was 236 F/g which dropped to 200 F/g after 25 CV tests, and decreased gradually to 190 F/g thereafter. The electrochemical behaviors during EPD and CV were examined by synchrotron X-ray absorption spectroscopy techniques from which it was deciphered that a reduction reaction from Mn 4+ to Mn 3+ occurred during EPD concomitant with re-oxidization during repetitive CV cycles. #
Journal of Materials Science: Materials in Electronics, 2016
problems [1]. It gives immense challenge to investigate high performance, low-cost and environmental friendly energy storage devices needed for modern civilization [1]. This can be achieved by clean energy sources and carriers, including hydrogen storage, lithium batteries and supercapacitors [2]. Amongst these, supercapacitors have attracted more attention due to their unique characteristics such as enormous power density, good reversibility, low maintenance cost, high cycling stability and environmental friendliness [3, 4]. Furthermore, supercapacitors ill the gap between conventional capacitors and secondary batteries. On the basis of energy storage mechanism supercapacitors are categorized into two groups: electric double layer capacitors (EDLCs) and pseudocapacitors. In EDLCs charges are stored by forming electric double layer of ions at the electrode-electrolyte interfaces while in pseudocapacitors charges are stored by redox reactions occurring on the surface of the electrode [5]. Carbon based materials like activated carbons, carbon nanotubes and graphene belong to EDLC's and transition metal oxides/hydroxides as well as conductive polymers are pseudocapacitive [6]. The transition metal oxides provide superior electrochemical performance with high speciic capacitances and good electrochemical stability [7]. RuO 2 based supercapacitors show good electrochemical performance, but sufer from high material cost and toxicity [8]. Therefore its comprehensive production is not beneicial. Other low-cost transition metal oxides such as SnO 2 , MnO x , NiO, CuO x , Co 3 O 4 , Fe 2 O 3 , TiO 2 , MoO 2 , and VOx are considered as ideal electrode materials in electrochemical supercapacitors [9-11]. Mn 3 O 4 and NiO materials have been studied extensively due to their superior electrochemical performance in pseudocapacitor as compared with carbon based materials. Mn 3 O 4 and NiO electrodes show low speciic capacitance due to its poor electrical conductivity.
Cathodic Electrodeposition of Manganese Oxides for Electrochemical Supercapacitors
ECS Transactions, 2019
Manganese oxide films for electrochemical supercapacitors (ES) have been prepared by cathodic electrolytic and electrophoretic deposition. The cathodic reduction of KMnO4 solutions resulted in the formation of manganese oxide deposits. In another approach electrophoretic deposition (EPD) has been utilized for the deposition of manganese oxide nanoparticles prepared by a chemical precipitation method. The films exhibited pseudocapacitive behavior in a potential window of 0-1 V versus SCE in aqueous 0.5 M Na2SO4 and 0.5 M K2SO4 solutions. The deposition methods allowed the formation of porous films which exhibited a specific capacitance (SC) in the range of up to 240 F/g. The SC decreased with increasing scan rate. The films prepared by electrolytic deposition showed higher SC compared to the SC of EPD deposits.
Manganese oxide films prepared by sol–gel process for supercapacitor application
Surface and Coatings Technology, 2007
In this study, manganese oxide electrodes with promising pseudo-capacitive behavior were prepared by sol-gel process using manganese acetate as the precursor. Effects of post-heat treatment on material characteristics and electrochemical properties were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), thermal analysis, synchrotron X-ray absorption spectroscopy (XAS), and cycling voltammetry (CV). Experimental results showed that manganese oxide films prepared by sol-gel technique exhibited Mn 2 O 3 and Mn 3 O 4 phases after heat treating at a temperature higher than 300°C. Meanwhile, a porous manganese oxide coating was observed due to the burnout of organics. The specific capacitance of the manganese oxide electrodes was 53.2, 230.5, 185.6, and 189.9 F/g after heat treating at 250, 300, 350, and 400°C, respectively. After three hundred charging-discharging cycles, the specific capacitance of the manganese oxide electrodes heat treated at 300°C decreased to 78.6% of its maximum. Synchrotron XAS examination revealed that manganese oxide electrodes exhibited the same trend where the trivalent manganese was transited into tetravalent manganese after cyclic voltammetry tests.
Study and optimisation of manganese oxide-based electrodes for electrochemical supercapacitors
Journal of Power Sources, 2009
A manganese oxide material was synthesised by an easy precipitation method based on reduction of potassium permanganate(VII) with a manganese(II) salt. The material was treated at different temperatures to study the effect of thermal treatment on capacitive property. The best capacitive performance was obtained with the material treated at 200 • C. This material was used to prepare electrodes with different amounts of polymer binder, carbon black and graphite fibres to individuate the optimal composition that gave the best electrochemical performances. It was found that graphite fibres improve the electrochemical performance of electrodes. The highest specific capacitance (267 F g −1 MnO x ) was obtained with an electrode containing 70% of MnO x , 15% of carbon black, 10% of graphite fibres and 5% of PVDF. This electrode, with CB/GF ratio of 1.5, showed a higher utilization of manganese oxide. The results reported in the present paper further confirmed that manganese oxide is a very interesting material for supercapacitor application.
Improved electrochemical performance of Mn3O4 thin film electrodes for supercapacitors
Materials Science in Semiconductor Processing, 2018
Fabrication of the Mn 3 O 4 thin film electrodes is an important area of research for the development of supercapacitors. Investigations were made to improve the electrochemical properties of the electron beam evaporated Mn 3 O 4 films. The films grown on stainless steel substrates at a substrate temperature of 473 K with subsequent annealing at 573 K for 4 h were in a single phase, which corresponds to the tetragonal structure of Mn 3 O 4 with I41/amd (141) space group. The Raman studies were also confirmed the single phase of Mn 3 O 4 films. The AFM data revealed that the surface of the films covered with dispersed vertical grains of size 36 nm with the rms surface roughness of 18 nm. The SEM image displayed the flower like growth of Mn 3 O 4 on the substrate. The films deposited at 573 K exhibited a specific capacitance of 568 F g −1 at a current density of 1 A g −1 in 1 M Na 2 SO 4 aqueous electrolyte with excellent capacitance retention of 93% even after 5000 cycles. The films annealed above 600 K were found to have mixed phases and corresponding capacitance decreased with annealing temperatures. The films annealed at 773 K exhibited only Mn 2 O 3 phase with a lower specific capacitance of 240 F g −1 .
Applied Sciences
MnO2 is the most favorable material in power storage due to its technological significance and potential applications in pseudocapacitance (due to various oxidative states allowing efficient charge transfer to meet energy demands), where its properties are considerably influenced by its structure and surface morphology. In the present study, a facile hydrothermal route was used to produce different phases of MnO2 (α, β, and γ) with different morphologies. The electrochemical performance of the synthesized phases was studied in aqueous sodium sulfate as an electrolyte. X-ray diffraction, UV–Vis spectroscopy, and Fourier-transform infrared spectroscopy were used to characterize the synthesized material. The surface morphology and topography were examined using field-emission scanning electron microscopy. The direct band gap of α-, β-, and γ-MnO2 was found to be 1.86 eV, 1.08 eV, and 1.68 eV, lying in the semiconducting range, further enhancing the electrochemical performance. It was f...
Thin Solid Films, 2016
Nanostructured MnO 2 films were prepared via cathodic electrodeposition under potentiostatic condition. X-ray diffraction (XRD) analyses reveal that the deposited films possess the hexagonal phase of epsilon manganese dioxide (ε-MnO 2). Fourier transform infrared (FTIR) spectroscopy studies also confirm the manganese dioxide phase of the deposited films. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) studies show that the film deposited at the potential of 0.2 V has a porous network structure which is made of sparsely distributed grains. Cyclic voltammetry studies show the maximum specific capacitance to be 259.4 F/ g at the scan rate of 5 mV/s for the film deposited at the potential of 0.2 V, while the chrono chargedischarge measurements on the film exhibit the maximum specific capacitance to be 325.6 F/g at the current density of 1 mA/cm 2. The variation in specific capacitance values of the films deposited at different potentials is attributed to different morphologies of the films.