- Francesco Lufrano added an answer:3Can someone address the two questions regarding gel electrolytes in an Electronic double layered supercapacitor?
1) Using gel electrolyte (solid state or gel state eg PVA/H2SO4) as a separator between electrodes wont cause quick self discharge of EDLC due to gel conductivity?
2) If gel electrolyte is solidified will it still be conductive enough to form double layer with electrode material according to my understanding electrolyte should reach the pores of electrode material and solid state wont?
If the capacitor is kept at rated voltage (e.g. 1V ) for about >10 min or more, the charge redistribution inside electrodes should be ended. More, probably the self-discharges is coming for faradaic shuttle reactions, which are not always reversible in particular in acid enviroment. The purity of the carbon materials also influences the shuttle irreversible reactionsFollowing
- Zameer Hussain Shah added an answer:6What is the best and reliable method to determine point of zero charge (pHpzc)?
i want to determine the point of zero charge ( pHpzc) of perovskite. in the literature there are many methods but i want to follow pH drift method (addition of salts) and method which involve the zeta potential vs different pH values. But the problem in all these methods is their variation w.r.t use of background electrolytes, concentration of electrolytes, volume of solution, time of stirring/shaking/sonication , amount of solid used.what is the standard parameters for all these methods. changing these parameters will change the value of pHpzc?
thanks Dr Jones. wt.% = [g solute/(g solute + g solvent)] x 100 so according to your statement 3wt/wt% means 0.3g for 10 ml total solution. i mean 3wt/wt%= 3 g/3 g solid+97 g water so for 10 ml aq solution will be 0.3 g soild. is that right?Following
- Artur Braun added an answer:3What is the relation between temperature of fuel cell and time?
i am trying to create a relation between temperature of fuel cell from start up to running to shut down with time? is it possible and if so how is it done ? for example a picture ha sbeen attached.
Google will help you accessing experimental data, see here for yourself
and it may also help you find some mathematical models. This will be part of your actual research for information.
I hope I could be assistance to you with this my 2nd reply here.Following
- Saeideh Hosseini added an answer:3What are the solutions to dissolve erbium oxide(Er2O3)? Does it dissolve in enthonal solution?
To prepare battery materials, i have used erbium oxide for synthesis.
you can see the attached linksFollowing
- Dalia Elgendy added an answer:21Can I do chronopotentiometry in potentiostat using a CHi 760d model?
I am doing it for a supercapacitor study. I got the data but I am not sure whether it is acceptable or not. Should I use galvonostatic charging discharging? I am attatching two of my chronopotentiometry data. Please help me.
what the function N/C and 2 Sensing electrode (Black)?Following
- Ashwani Kumar added an answer:7What is the effect of crystalline material on a pseudo capacitor?
I have deposited MnO2 nano particles but they have poor crystallinity and the BET surface area is high. the specific capacitance is lower.
- Vishal Chaudhary added an answer:6Is it possible that values of dc-electrical conductivity of amorphous chalcogenide bulk samples are less than their values for amorphous thin films?
Please, Can any one answer me
Is it possible that, the values of dc-electrical conductivity of amorphous chalcogenide bulk samples are less than their values for the amorphous thin films under the same conditions of temperature, pressure, composition and the surroundings ?
This is due to the orientation difference as suggested by Prof. ManeFollowing
- Sergio Mollá added an answer:7What is the conducting material at the cathode in a commercial lithium sulfur battery?
The lithium sulfur battery appears to be a near commercial product. There is a claim that such a battery product is an improvement over conventional commercial lithium ion batteries. In all of the announcements and papers I have read the chemical nature of the cathode is not revealed. In addition to sulfur it must contain a conducting material. What is that conducting material? Furthermore is there no carbon at the anode as there is in a commercial lithium ion battery. Is there any danger of dendrite growth at the anode. Furthermore, does anyone know what the electrolyte is?
In literature you can find many examples of materials. Recently, Li3OX (X=Cl, Br) compositions are gaining attention as solid electrolytes. As an example of the interest of companies for this technology, please check the following link of NEI Corp. which also reports in general the kind of materials are considered.
- Nallal Muthuchamy added an answer:15What is the best substrate for supercapacitor application?
I am trying to put MnO2/C composite on Al foil, however, the foil is getting damaged after couple of days. Please suggest me some alternate.
Dear Ahmed A. Farghaly,
I want use Nickel foam as a substrate for supercapacitor application. I need some idea about fabrication methods, can you please share your experience?
Thanks in advance.......Following
- Alexander T. Morchenko added an answer:4Why imaginary part of dielectric constant Vs frequency show a decreasing behavior in low frequency region?
Why imaginary part of dielectric constant (e'') Vs frequency show a decreasing behavior in low frequency region (for ferrite) ? However in many books i found imaginary part of dielectric constant (e'') Vs frequency in low frequency region seems to be constant and equal zero.
Since the mechanisms of loss (dissipation) of energy are associated with dynamic changes in the system state, then the losses increase with increasing velocity (and amplitude) of these changes. Accordingly, the losses in the low frequency region described by the imaginary part of permeability, below\ the losses (which are described by the imaginary part of permeability) become lower at low frequencies.
In addition, some of these materials (for example, MnZn ferrites having appreciable electrical conductivity) have contribution to losses make eddy currents Foucault, which decrease with increasing frequency electromagnetic field. However, in most experiments it is impossible to clearly distinguish the value of e" deposits purely dielectric and electric (Joule effect) losses.
However, in most experiments it is impossible to clearly distinguish the contributions of purely dielectric and ‘electric” (Joule effect) losses in the value of e".
- James H Adair added an answer:1Will the existence of spinodal decomposition be altered by the homogeneity level of a mixed metal oxide (M1,M2)O_(2-x) polycrystalline ceramic?
In the studied ternary system we observe a very narrow miscibility gap (consisting of two cubic structures with slightly different oxygen content) and we are wondering whether a spinodal domain exists within it. The G-x curve suggests an extremely narrow chemical spinodal domain. The follow-up question would be - is there anything that can hint towards the existence of a coherent spinodal domain, like the kinetics of demixion or properties of the material? Would the spinodal line be altered by the physical form of the material (bulk polycrystalline or fine powder)? If the demixion (formation of the second phase) is extremely quick (due to the high mobility of oxygen and narrow shape of the gap), would it make it impossible to achieve sufficient undercooling to reach the coherent spinodal? What would be the results if we traversed the miscibility gap (during an isothermal plateau), i.e. crossed the binodal, and spinodal domains during an in-situ XRD experiment - would we observe some kind of an event while crossing the coherent spinodal line? Is the characteristic periodicity of the microstructure necessarily in the nano-scale or can it be in the micro scale for certain compounds?
Since spinodal decomposition is due to localized thermodynamically driven instabilities, homogeneity is a consistent driver. Spinodal decomposition was first discovered in glasses during the 1950-60s and was first described theoretically by Cahn and Hiliard. The net effect in glass is that regions rich in for example a sodium-silica composition relative to a pure silica phases separate leading to nano- to microscale interconnected glass of different composition. If there are heterogeneities present, nucleation driven phase separation is more likely rather than spinodal decomposition. Thus, homogeneity is critical to have spinodal decomposition rather than nucleation-growth processes.Following
- G. C. Nayak added an answer:7How can I explain the capacitance value with the attached EIS data?
I am working with the supercapacitors and studied with three of my sample with EIS in CH660D with a three electrode system and got the attached EIS. While the GA is just a combination of carbon and conducting polymer 2nd and 3rd contain some metal oxide. I got higher capacitance in the third. How can explain the capacitance value with this EIS?
Thank you very much and I will do the analysis below 1 Hz and try to find out the difference. But why for the same frequency range GNA possessed a very high Z' and Z'' value as compared to other two systems?Following
- Shuijian He added an answer:2Can we use surface contact for CV and galvanostatic charging/discharging measurement in supercapacitor device application?
I have deposited MnO2 thin films by spin coating on ITO glass substrate. Can we use surface contact for above mentioned measurements as its back side is insulator?
Please see the paper "Fabrication and electrochemical characterization of two-dimensional ordered nanoporous manganese oxide for supercapacitor " for more information.Following
- Subrata Ghosh added an answer:2How the mass of carbon nanowalls/vertical graphene can be calculated for specific capacitance measurement?Carbon nanowalls/vertical graphene grow vertically on substrates. To calculate the specific capacitance from cyclic voltammetry measurement, I wanted to know how the mass of the samples can be calculated. Can someone provide any reference regarding that?
Dear Dr. Viscor,
Nice to get reply from you. I'm agree with you and I already started in you suggested direction.
Thank you very much for your valuable comment.
- Hae-Yoon Choi added an answer:8Is there any hydrogen storage alloy which has low melting point?
Hi. I'm planning the experiment using hydrogen storage alloy.
The experiment will be carried out like below.
First, dissolve a lot of hydrogen in alloy as possible.
Second, heat the alloy using induction heating and the alloy is melted after all.
Third, the hydrogen is emitted from the alloy.
I want to know the alloy that has low melting point..
Are there any papers that describe the information about hydrogen dissolve conditions or properties?
Thank you Ressell Barton, Alexandre A C Asselli.
I learned a lot, thanks !Following
- Tamoghna Mitra added an answer:4Does anyone know how to measure LUMO-HOMO from CV?As I searched there are different formula for it which I don't know which one I should use? And what is different between them?
1) E LUMO=-(E red (onset)+4.4)
2)E LUMO=-[4.65 V-E red(onset)]
3)E LUMO=[(E red-E 1/2 (ferrocene)+4.8 ]
4)E LUMO=-(E red (onset)-4.4)
But how do I get step 1 i.e., "..get the HOMO level as the first oxidation of the molecule using CV."
I guess HOMO = -[4.4+Eox(onset) (Vs Fc)] V
Eox(onset) (Vs Fc) = oxdidation onset compare FcFollowing
- George H. Lane added an answer:10How can I reduce a large iR drop in a nickel carbon based supercapacitor?
I am doing a galvanostatic charge discharge using the Gamry Poteniostat with a voltage window from 0-0.5 V and 3 electrode setup. When I charge my electrode it takes about 2000 seconds to reach 0.5 V however, it discharges either in 60-120 seconds. The iR drop is about 0.2 V which is pretty high. When I test it at a higher current density the discharge is in milli seconds. I would like to know how I should reduce the iR drop? I tried various concentration of electrolytes from 0.5 M- 6 M KOH but it still shows the drop. The ESR of the electrode is about 4 Ohms which is high.
Additionally, I would like to know what program in Gamry has to be used to study the effect of CD on Charge discharge behaviour? I use the Cyclic Charge discharge and calculate the specific capacitance. Is there anyother program that should be used?
Try compacting the electrode using a roll-press.
It's not clear if your system is a NiO-Ni(OH)2 redox device, or just a nickel metal double layer device.Following
- Jason Mclafferty added an answer:10From where does the electron come in the Oxygen Reduction Reaction?
When we assemble a full fuel cell, electron comes from the hydrogen oxidation.
I don't understand when we study only Oxygen reduction reaction, in a 3-electrode set-up , from where electrons come for that which we calculate from K-L plots??
I think what Juan Casado said explains your question regarding the flow of current being in the direction opposite of electrons. As he says, in electronics and electrical circuits, "conventional current" is taken as the flow of positive charge. It gets confusing in electrochemistry, because the definition of anode and cathode are referred to the flow of electrons. This makes it more complicated to understand the interfacing of electronics and electrochemical cells - you have to be careful with the "book-keeping."
To build on what other said, the potentiostat is moving electrons from the counter electrode to the working electrode or vice versa (through the wires and potentiostat circuit), depending on the reactions occurring. For example, in your case, the working electrode is supporting a cathodic reaction. The conservation of charge dictates that the electrons have to be supplied quantitatively by another reaction. This reaction occurs at the counter electrode. So for a cathodic reaction at the working electrode, there is an anodic reaction at the counter electrode. The electrons flow through the potentiostat circuit from the counter electrode to the working electrode and ions move through the electrolyte to enforce electroneutrality in the solution. So there are two kinds of current - current through the external circuit (wires and potentiostat) and current through the electrolyte. If you remove one of these paths - no current flows and you have no electrochemical reactions.Following
- Ioannis Samaras added an answer:5Can one use a Cu foam/foil/plate as current collector for testing super-capacitor electrode loaded with Ni(OH)2?
I found most reports about nickel hydroxide / oxide electrodes said that they used Ni foam as the current collector. Can one use a copper foam or foil instead for testing Ni hydroxide/oxide electrodes in alkaline solution? I found this an issue because Ni foam contributes quite a lot in the scanned potential range (0-0.4V) and shows significant redox peaks.
An alternative is Titanium Foam, "stable" in alkaline media.Following
- Francis Salzano added an answer:7Can two dimensional materials be used as electrolytes of fuel cell?
One question about solid state fuel cell: Can the van der waals heterostructure be used as electrolyte of fuel cell? In other words, van der waals heterostructure is impermeable or permeable to proton or Oxygen ion?
Please supply more information.Following
- Subramanian Ramachandran added an answer:2What kind of coolant for hydrogen storage in metal hydrides should I use?
The use of a coolant is necessary to regulate temperature in hydrogen storage tank based on metal hydrides. What kind of coolant is more efficient and most used actually?
Hi, based on my experience, for transition metal hydrides with enthalpy of absorption about 30kJ/mol H2, water as a coolant worked well in keeping the temperature constant during exothermic hydriding process as well during the endothermic dehydriding process. . However, proper designing of the heat and mass transfer aspect is important.Following
- Tsvetanka Babeva added an answer:7How can one obtain pure V2O5 films by the sol-gel method using vanadium tri-isopropoxide?
I have prepared V2O5 films by sol-gel method using vanadium isopropoxide. The calculated extinction coefficient decreases with wavelength in the range 400-550, have a minimum around 550 nm and starts to increase for wavelength greater than 550 nm. Is it possible some other oxide to be presented in the film? How to obtain pure V2O5 phase.
Thank you very much Dr. Carlos Araújo Queiroz! I will try to use acetone. Just to mention that it is not possible to use water with VTIP because even very small amounts lead to precipitation. Till now we have obtained clear sol only using isopropanol alchohol. Even the usage of ethanol leads to the same effect as using water. The problem is that the deposited thin films have a relevent absorption that lead us to the conclusion that mixed oxides exist.Following
- Zol Bahri Razali added an answer:1What are the competing technologies of shape memory polymers (SMP)?The applications of SMP in consumer durable has been very limited. No real applications can be found despite the advantages of SMP. I observed that there have been very less awareness on SMP among the decision makers (e.g. designer, product engineers) in the industry. I believe certain technology has been favored over SMP (for instance mechanical actuators) because of specific factors.
my questions is: can anyone kindly provide me examples of competing technologies of SMP in any application area.Following
- Asif Mahmood added an answer:5In asymmetric supercapacitors, metal oxides are used as which type of electrode? And what about reduced graphene oxide?
(Cathode and Positive) or (Cathode and Negative) or (Anode and Positive) or (Anode and Negative)?
Hello, These papers describe the potentials for corresponding electrode materials and tells us how to use materials.
Hope it will be helpful
- Arvinder Singh asked a question:OpenHow can one perform time limited OCP (open circuit potential) measurement in Autolab Nova 1.10 ?
I want to measure OCP of a supercapacitor device for a time period (say for 10 hours). Is it possible with Autolab Nova 1.10?
I didn't find options for time limited OCP measurement, however, we have options for d(OCP)/dt limited OCP measurement.
- Siva Subramanian added an answer:4How do I measure charge-discharge in a supercapacitor using chronocoulometry ?
How can I perform charge-discharge measurements on a supercapacitor material in a standard 3 electrode set-up using the Chronocoulometry technique. I am using CHI604D workstation, if that helps. I have come across one article (see link below) that uses this technique for charge-discharge measurements, but the authors have not explained the details of the same.
As santimoy pointed out electrochemical charge discharge in a supercapacitor can be measured by chronopotentiometry. For further reference kindly have a look with the attached paper.Following
- Closed account added an answer:2How to convert a potential collected with reference to Ag/AgCl to Reversible Hydrogen Electrode?I have collect a cyclic voltammetric data by taking Ag/AgCl as the reference electrode. But I want to convert this one to Potential with respect to Reversible Hydrogen Electrode. Please suggest me the required conversion equation. 0.5M H2SO4 was taken as the supporting electrolyte.
- The general equation for this conversion at any pH using Ag/AgCl reference electrode is:
- E(RHE) = EAg/AgCl + 0.059 pH + EoAg/AgCl
- Where EoAg/AgCl = 0.1976 V at 25oC and E Ag/AgCl is your working potential
- Mazdak Hashempour added an answer:16Does anyone have an idea about the adhesion of a carbon paste to Al for supercapacitors?One of the methods of electrode preparation for electrochemical capacitors is to cast a paste of active material (mainly containing carbon nanostructures) on a metal sheet (Al or other metallic substrates). However, the adhesion of the carbon layer to current collector is always an issue, especially under the applied electrochemical conditions. The paste components are usually like: Activated carbon+ [CNT or Graphene or pseudocapacitive materials & etc.] + a polymeric binder (PVDF, PTFE) + an organic solvent (NMP).
So, how can we improve this adhesion?
Nice to hear from you again after Lausanne and thanks for participating the discussion.
Honestly, we have not focused deeply on the corrosion of Al substrate. We either use the direct growth of active material (mainly CNTs) on Al for supercap (like these papers: Supercapacitor electrodes by direct growth of multi-walled carbon nanotubes on Al: a study of performance versus layer growth evolution AND Growth of carbon nanotubes on aluminium foil for supercapacitors electrodes) or the paste method. In case of growth method, we have not encountered the contact and adhesion problems of the CNTs to Al and so, we have not gone through the corrosion issue though it is definitely worth investigating. Especially, considering the point that our studies have been mainly focused on the material’s capacitive behavior and therefore, we have not gone through long and severe life cycling experiments. Although below 10K cycles the systems works reasonably, in longer cycles, maybe up to 100K, there is no guarantee that it remains as good as it was. So, it should be tried. The potential window in those cases (direct growth) is usually less than 1 V (0.7-0.8 V) and the collector is high purity Al. We didn't try other alloys and we didn't observe corrosion products or color changes on collector or separator. Pitting and other microstructural checks yet remain to be carried out in case we plan to monitor the longer cycling behavior of the system.
The problem of adhesion however, refers mainly to the paste method where even before starting the electrochemical characterization, the electrodes suffer from delamination and cracking. I have seen some works using special pretreatments on substrate with special conductive adhesives (like Electrodag EB-012) to enhance the adhesion of the paste to the substrate (see the suggestion by Steffen Schlueter in this discussion and his paper: Strategies to Reduce the Resistance Sources on Electrochemical Double Layer Capacitor Electrodes). Moreover, in our work, we do not prepare the active material as a separate film to be put on gold or Al current collector, but we try to cast it on the current collector to make it more realistic in practical point of view and more similar to a supercap electrode. Here is where the problem of delamination and cracking comes up even before the start of the characterization.
Have a good time
About Materials for Energy Applications
Development and Characterization of Metallic and Ceramic Materials for Energy Applications