- 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 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
- Matthew Monari Ombaba added an answer:What initial charge/discharge rates should I use for Li-ion pouch cells?I am making "coffee bag" batteries, aka pouch cell batteries. The cathode and anode are LiFePO4(Al) and CMS graphite(Cu), respectively. The electrolyte is 1M LiPF6 in ethylene carbonate, dimethyl carbonate and diethyl carbonate. All materials are bought as prepared.
I made a 3 cell battery that should have ~74 mAh capacity. I originally reached this capacity, but the capacity is dropping with each subsequent charging/discharging cycle. The charging cycles are as follows:
Constant Current Charge - 8.2 mA up to 4.0 V
Constant Voltage Charge - 4.0 V until 0.1 mA
Rest - 5 min
Constant Current Discharge - 8.2 mA until 2.5 V
Rest - 2 min
The rate is ~ 0.11C.
Why would the capacity be dropping? Water contamination? Gas build up?
A rule of thumb when characterizing most batteries is to do a C/20 charge- discharge cycles. Normally, commerical batteries use this cycles to determine their capacities. I would stick to that. From my experience, dont work in a Nitrogen filled glovebox if you want to avoid errors. I would keep a potential window of between 1-3.6V. Hope this helps.Following
- 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?
What about adding some surfactant to the paste mixture? Does any body think that the addition of something like CTAB, TWEEN, SPAN, Triton X-100 or other surfactants can help?Following
- Aneeya Kumar Samantara added an answer:Can anyone help me to get a JCPDS software for XRD analysis comatible for 64bit OSI am using a laptop of OS 64bit. The JCPDS used for XRD analysis only supports the 32bit system. Kindly help me to get a JCPDS software which will be compatible for my PC(64bit).Thanks Prashant, I'll try that one. If some problem occur then I must ask you.Following
- Juan Casado added an answer:Is it time to think other catalyst than TiO2 for water splitting?There are so many papers on water splitting using TiO2 based photocatalysts. However, the yields of hydrogen production are very low. I think some compositions other than the trends need to be synthesised and tested...I would like to have your opinion on this and would like to welcome your views.Anwar, Any data on the stability of the system you have worked in?Following
- Manohar Sehgal added an answer:Can we conclude that the performance of Indium tin oxide nanoparticles are better than bare tin oxide nanoparticles for various applications?Comparison between ITO and TOThe superiority of[ ITO] over [TO] can well be authenticated from the following two references .In fact the above answer gave a “resume” of these two references for your kind perusal:
[A]Journal of Nanoparticle Research 12(7):2597-2603].
[B] J Am Chem Soc. 2009 Dec 16;131(49):17736-7].Following
- Morteza Karimzadeh added an answer:Which are the best sulphurizing reagents for SILAR deposition?I'm thinking about Na2S, but I was wondering if using any organic reagent like thiourea (it should thermally decompose at low temperatures) would be suitable too? ThanksIt may be possible to use KSCN to do sulphurizing. Such compounds can also be applicable in higher temperatures.Following
- Azrol Kassim asked a question: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.Following
- Chunhua Cui added an answer:Does anyone know the reported highest photocurrent of doped/non-doped hematite Fe2O3 photoanode without introduction of any cocatalysts by Vis light?It is driven by visible light above 400 nm. One reference please and I would like to mention and cite it.Thanks, João.Following
- Gerro Prinsloo 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?You can study this method:
Or search for similar in the search boxFollowing
- Alaa J Mahrath added an answer:Is there a simple way of converting chloride to alkoxide?I have some chlorides (zirconium, titanium and silicon) and would like a simple way to convert them into alkoxide? Is it possible? Is the reaction dangerous? If you can provide me some information or literature, it will be very welcome.This is depend on what you want to do after alkoxide formation. as you know in most cases the alkoxide can be formed by rxn of metal group (I or II) elements with alcohol this type is highly reactive ( strong base).if you look at IE of sodium , zirconium and magnesium (5.1 ,6.6 and 7.6) ev. so the Zr can be converted to alkoxide .Following
- Christopher F Buurma added an answer:What are the alternatives and workarounds for Solar Simulators in DSSC Research?I am involved with research on Dye - Sensitised Solar Cells (DSSCs) at an institution which does not currently have (and presumably cannot afford) a solar light simulator. I was wondering if there are feasible alternatives to obtaining a simulator, and possible implications on the quality of the research and data obtained. We had considered calibrating a Xenon lamp to obtain 1000W/m^2 equivalent light intensity, but the logistics involved in designing a working testbed would probably be a diversion from the main focus of the research.
The institution is a University located in the Tropics, and has clear, sunny weather for most of the year, so extended data collection (via datalogger) might be a last resort alternative.I will also warn that you should invest time/effort into properly calibrating and controlling your light source. You can save hours, days or weeks of wasted time by having reproducible and representative data. Without a proper light source there are techniques to use other light sources and a known QE curve for your device. These spectral matching methods are often used as a corrective measure on near-solar simulated light.
- Alberto Battistel added an answer:Is it possible to theoretically calculate a CV curve for a capacitor model?Is there any method by which we can get the cyclic voltammetry curve (CV curve)
theoretically?if you want to simulate the CV of a capacitor, you just need to check the equations in wikipedia about capacitor. Once you have the I-V relation, just plug in a potential ramp up and down. It is rather easy. with only a C/R system the CV comes a kind of rectangle. This becomes larger and larger increasing the scan rate.Following
- Erie H Morales added an answer:Where can I get single crystal n-type doped CdTe?I need to conduct an experiment using a wafer of n-type doped single crystal CdTe but I cannot find this available anywhere. Does anyone know where I can find this material?Hi Matthew. Then try
- Bradley Brennan 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)It looks like your equations all convert LUMO into eV vs vacuum reference. That isn't really a conventional thing to do for materials where you determine your electrochemical potentials using cyclic voltammetry (CV). It is more common for those working with inorganic semiconductors in a pure solid state device setup, and you would likely use the more solid state materials methods for determining the bandgap/Fermi levels, etc. CV is generally used for organic materials and referenced to things such as ferrocene or other common references.
If you are analyzing an organic/organometallic dye, and it functions by absorbing light and transferring an electron to something like TiO2, then you would performing the following experiments:
1. You would get the HOMO level as the first oxidation of the molecule using CV.
2. You would get the emission spectrum using a fluorimeter, and determine the excitation injection energy (in eV) for the molecule (singlet or triplet energy). You can find out how to find the exact value online if you have a large stokes shift.
The equation for the LUMO would then be LUMO = HOMO - Excitation energy(eV) , and the output values for HOMO and LUMO would be in Volts vs. your reference.
Note: Many people use CV to get the oxidation and reduction potentials, subtract them, and see that as the HOMO-LUMO gap. That is incorrect because the LUMO level doesn't contain an extra electron, and due to reorganizational energy differences, the LUMO value calculated this way can be way off.Following
- Muhammad Fahad Ehsan 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?You yourself told one of the possible answers about doping your compound with different metals such as Mn, Cr etc.
If just improving the conductivity is your aim, you can also do Au-sputtering for this!
- Qiang Wang 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.Thank you very muchFollowing
- Rajasree vjx added an answer:What is the most current catalyst suitable for fuel cell purposes?I need a suitable catalyst with high performance towards oxidation of glycerol.Following
- Alexander Eifert 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 potential of the RHE depends on the pH of the electrolyte solution. In 0.5 M H2SO4 the pH is close to 0. Therefore the potential of the RHE can be calculated to E0=0.0 - 0.059 * pH; in this case the potential of the RHE is therefore also 0.0V.
The potential of the Ag/AgCl electrode depends on the concentration of the solution used in the electrode itself. If you have a sat. solution then the potential is +0.197V. To convert now your CV data recorded with the Ag/AgCl electrode you have to shift the recorded potential according to this equation: E(RHE)=E(Ag/AgCl) + 0.197V. So you must simply add to your existing potential the shift of the Ag/AgCl electrode. If you have a Ag/AgCl electrode with 3.5M then add +0.205V or +0.210V for a electrode with 3.0M.Following
- Vishal Mahesh Dhavale added an answer:Can anyone tell me about the role of heteroatoms (S, N) during carbon dissolution in a metal matrix (Fe, Ni etc)?Some of the metals like Fe, Ni have the carbon dissolution property. In such case if we use N-doped graphene or S-doped graphene, the present heteroatom will affect the carbon dissolution property in Ni or Fe.Thanks for the clue. However, the carbon adsorption and dissolution are the simultaneous process and depend on the plane energy. However, is the hetro atom will helps to trigger the same. If anybody have such reference. Please give me the links, if possible.Following
- Subrata Ghosh asked a question: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?Following
- Nuno Vitorino added an answer:What is the theoretical density of Ca3Co4O9 and Zn0,98Al0,02O?In the frame of my internship, I'm looking for the theoretical density of Ca3Co4O9 and Zn0,98Al0,02O.Dear Ayoub
For Ca3Co4O9 theoretical density see this paper...
- BALAMURUGAN Matheswaran added an answer:Can anyone suggest a method to synthesize of Pt/CNTs nanocomposite?.Microwave assisted synthesis of Pt/CNT nanocomposite is one of the best non toxic, environment friendly grren method. Hereby, one of the best reference article is
Weimin Zhang, Jun Chen, Gerhard F. Swiegers, Zi-Feng Ma and Gordon G. Wallace, “Microwave-assisted synthesis of Pt/CNT nanocomposite electrocatalysts for PEM fuel cells”. Nanoscale, 2010,2, 282-286 (DOI: 10.1039/B9NR00140A)Following
- Alexandre Mantion added an answer:How can I identify specific phase of WO3 from XRD?Since the intense 2 theta angles from WO3 XRD peaks seems similar for monoclinic, orthorhombic, and tetragonal phases, how can they be distinguished? is there any specific observation for identification or distinguishing?Are they similar in intensity? Check with simulations!Following
- Andreas Hess asked a question:What are the concentration and temperature dependent electrolyte properties of commercial SelectiLyte LP40?I am interested in a full set of transport properties for the LiPF6 based electrolyte SelectiLyte LP40 from Merck / BASF analogously to the outstanding work of Valoen and Reimers (J. Electrochem. Soc. 152, A882, (2005)).
Are there any data available?Following
- Prakash Ramakrishnan added an answer:What are the advantages and disadvantages of using glassy carbon working electrode for supercapacitor applications?Can someone share merits and demerits of using glassy carbon electrode for supercapacitor application?I agree with Prof. George chen. Advantages: Using Glassy carbon electrode as a working electrode, one can understand the material electrochemical properties at ease since no complication in preparing electrode ink like in 2-electrode cell. However, it is simply a primary study like another 3 electrode system. Also, before going to make a full cell one should understand systematically wherther the material is suitable or not?.Following
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