- Sergio Mollá added an answer:What 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.
- Jian Yang added an answer:What 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.
consider your electrolyte and replace the collector by Ni foam ，TiFollowing
- Alexander T. Morchenko added an answer:Why 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:Will 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:How 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:Can 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:How 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:Is 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:Does 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:How 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:From 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:Can 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:Can 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:What 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
- Tanujjal Bora added an answer:What is the purpose of uniform thickness of titania films in Dssc? What should be the thickness value?
what is the good thickness value ?Following
- Tsvetanka Babeva added an answer:How 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:What 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.
Please visit to this journal
- Asif Mahmood added an answer:In 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:How 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:How 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
- Sai Siddhardha R. S. added an answer:How 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:Does 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
- Rasu Muruganantham added an answer:How can we improve the conductivity of the olivine structure LiFePO4 with other transition elements?Do you think that the substitution of Fe in LiFePO4 or doping Mn, Mg, Cr or Co, improves its poor conductivity?Following
- Daniel Marinha added an answer:If a material is not only ionic conductive, but also electric conductive, how to measure its ionic conductivity and electric conductivity separately?I want to measure the electric and ionic conductance of slurry.
I would be very careful in following Huggins simplistic method to determine mixed conductivity by impedance spectroscopy. see j. maier's work on the topic.Following
- Michael Dubrovsky added an answer:Can someone suggest a battery chemistry which has equilibrium concentrations very sensitive to temperature?See this google drawing I made to illustrate a hypothetical battery system where the equilibrium point (where battery is considered "dead") changes with temperature.
I am looking for battery chemistry where this shift is dramatic. Common/cheap battery chemistry preferred but exotic ones would be interesting as well.
Also, would take a suggestion for a good reference which provides experimental data on the dV curves as they relate to T for various battery reactions.
In theory this shift would be dramatic in battery chemistries that have high entropy difference between product/reactants. I can think of some examples but interested to see what others think/know empirically.
- Subbukalai Vijayakumar added an answer:Could anyone tell me how can to measure IR drop?I want to measure IR drop. Is there a way to measure it from galvanostatic charge/dicharge curve?
Charge-discharge is time against potential diagram. Straight line part in the discharge curve from maximum potential give the value of IR drop. If you want to measure IR drop means, In discharge part
1. note down the maximum potential and time (s) - V1
Consider max potential is 1 V at 60 s.
2. Note down the minimum potential in the same time -V2
low potential in 60 s is less then 1 V, say 0.98 V
The difference between V1 and V2 is IR drop. So 1 V - 0.98 V = 0.02 V is IR dropFollowing
- Mazdak Hashempour added an answer:What is the difference of Internal Resistance (Ri) & Equivalent Series Resistance (ESR) in the context of supercapacitors’ resistance & power density?
Equivalent Series Resistance (ESR) and Internal Resistance (Ri) are two measures for the evaluation of a supercapacitors' resistance. The former is evaluated through the electrochemical impedance spectroscopy (EIS) and the latter, through the cyclic charge-discharge (CCD) experiment and the potential drop on current peak at the initiation of the discharge. Disregarding the obvious distinction in the method used for their measurement/evaluation, what is their difference (if any)?
Basically, the sources of the resistance in a supercapacitor are the same independent from the method used to measure and quantify them:
The intrinsic resistance of the electrolyte (R electrolyte), diffusion resistance of the electrolyte among and into the porous structure of the active material (R diff), contact resistance between the active material and the current collector (R cont) are the most well-known sources of the resistance.
From the other hand, ESR and Ri, to the best of my knowledge, are intended to measure the same things. So, as far as the global magnitude of the cell resistance is concerned (like in the case of power density estimation, where, the specific contributions of the different components to the global cell resistance are not important, but their summation instead) why should ESR and Ri be different? and if they are, what is the criterion for the use of either ESR or Ri ? There is no reliable agreement on this in the literature (some use ESR and some other the Ri).
Yes, generally EIS is a more complicated method compared to the other technique and delicate elaborations are required to extract the data (eg., ESR) out of it. But about the precision and accuracy and reliability of the data (I mean in this case, for the overall resistance) I am not sure which one could be better.Following
- Debarati roy chowdhury added an answer:Can 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.
Dear K.P. thank you. I am really grateful to you. In that paper they have done without separator. Now I can do chronopotentiometry in potentiostat.Following
- Mustafa Kamal Mohamed yousef Kamal Kamal added an answer:How do we calculate d-spaces from SAED pattern?I have taken SAED pattern of my Titania sample. It is showing that the sample is polycrystalline with clear boundaries. I calculated d-spaces using Image-J, but the d-spaces values are not matching with the XRD pattern? I attached the electron diffraction images below. Could you suggest me how to calculate or how to match d values with XRD?
The interpretation and indexing of spot patterns from single - crystal are nearly always carried out using the concept of the reciprocal lattice originally by Ewald and Von Laue. The reciprocal lattice is one composed of a system of points , each of which represents a reflecting plane in the crystal and has the same indices as the corresponding reflecting plane.
dr = Camera constant . R it is easy to measure directly from the phtographic plate and once r is indexed , camera constant can be established . This is not eadsy to do if bthe structure is not Known . The Camera Constant will also vary with the lens current used so that camera constant must be worked out of each pattern that is obtained .
Once Camera Constant is known for the microscope the diffraction patterns may quickly indexed simply by dividing Camera Constant with the measured distances r of the spots from the origin in this way d- spacings are obtained directly .Following
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