Hi, can anyone help me to define why the specific capacitance of the electrode has been fallen during the first few cycles of GCD stability test?
Stability test of the binder less (Ni/Graphene) electrode was recorded via GCD technique. The experiment conducted in three electrode system at loading current of 5.5 (mA/cm2) or 2.6 (A/g) for 2250 cycles (30 h). Potentials represented Vs. (Ag||AgCl) and electrolyte was 1 M of NaCl solution. a) Plot of selected cycles, and b) Respective specific capacitances of them
Capacitive deionization
Supercapacitor
Galvanostatic charge - discharge
Initially, the electrolyte was not fully penetrated in pores of the electrode material.
In a circuit, if ringing occurs it makes the circuit unstable. So, we have to do the stability test. For example, We can measure the phase margin at unity gain of the loop gain to optimize the chosen value of capacitor, resistor, and inductor in an RLC network. I wonder to know what the meaning of the stability test is in your work.
Dear Muhammad Usman,
The phenomena that you talk about has been occurring between 50 to 1000 and consequently the specific capacitance increases. But what phenomenon reduced the specific capacitance before the cycle number of 50th?
Dear Tran Tri
We have used Galvanostatic charge/discharge method to examine the stability and life cyclability of the electrode.
I am wondering if you repeat your measurement, it would be same or not!
For me it seems like that in the first a few cycles, the ions could not penetrate in the electrodes properly (due to the agglomeration of the sheets maybe?) and in the later cycles the porosity of the electrode material was increased, resulting in the higher capacity.
I am not sure how the porosity of the electrodes could be tested before and after the electrochemical tests to investigate any changes...
Hi, Hossein Jeddi
It's a good idea, could you suggest any reference about it ...
Hi Majid Talebi , maybe the non-homogeneous surface of your binder-less (Ni/Graphene) hybrid electrode ('h-WE') includes additional phases, and/or maybe there is a (new, possible,) strategy behind this 'h-WE' formation.
The surface of the 'h-WE' might contain, also, some other hollow nanospheres (GHSs) anchored[1] on Graphene showing, initially, a low(er, e.g. GO[?] and/or other non-rGO) total specific capacitance, before the 50th cycle number. Also, these 'h-WE' might be responsible for such[2] an evolution reaction, showing a recover of the total specific capacitance.
1. Ruthenium Nanoparticles Anchored on Graphene Hollow Nanospheres Superior to Platinum for the Hydrogen Evolution Reaction in Alkaline Media https://pubs.acs.org/doi/full/10.1021/acs.inorgchem.9b03201
2. Your quotation [Majid Talebi]: "The phenomena that you talk about has been occurring between 50 to 1000 and consequently the specific capacitance increases. But what phenomenon reduced the specific capacitance before the cycle number of 50th ?"
Deepak Sridhar
Yes, It's true, this is a memory effect and we can see this phenomena just at the begging of the test. I want to find why this will be happening and what is the mechanism of it ... ?
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