Any other reason except the less participation of electrolyte ions (with increase in current)?
You meas current density. If so increasing scan rate or current density don't give charges enough time to migrate through pores. That produce a lower specific capacitance compared to lower rates.
Hello Tapas Das,
Normally, Increasing current density causes lower specific capacitance value in CD measurements. But If nanostructured characteristic of the material with segregated particles permits better permeation of the electrolyte ions, then the capacitance value will not vary so much.
The less capacitance value at higher current densities is principally due to the prime contribution of the Ohmic drop (ESR) and sluggish kinetics of electrochemical activities at that higher current densities. Most of your as-prepared nanostructured material can't be efficiently participate in the electrochemical reactions at high current densities, resulting in low capacitance value. You can check my recent publications too for detailed interpretation.
This can be attributed to the slow faradaic reactions occurring at the electrode. We have discussed this phenomenon in our two papers. You may read those papers, it may be helpful for understanding the matter.
1. Article Three-Dimensional Nanoarchitecture of BiFeO3 Anchored TiO2 N...
2. Conference Paper Synthesis of BiFeO3 nanoparticle anchored TiO2-BiFeO3 nano-h...
Paper 2 would be much helpful for you, I guess.
The effective thickness[1] (and morphology) of the electrical double-layer (EDL) affect strongly[2] the 1)density of the adsorbed ions, and the 2)activation energy for high values of pseudocapacitance. The effective thickness of the electrical double-layer (EDL), acting as a virtual "membrane", separating dissolved ions priorities, decreases along with the increase of the charging current. So, this is one of the main (surface catalyzer, based) reasons for a decrease in specific capacitance (in supercapacitors) with the increase in current.
1. Thickness of Electrical Double Layer: Effect of ion size http://physics.fe.uni-lj.si/publications/pdf/electrochim1.pdf
2. Carbon electrodes for capacitive technologies https://www.sciencedirect.com/science/article/pii/S2405829717307171
Dear Tapas Das , please read the articles (espcially the second one) whose links have been given in my previous answer. I hope the articles may help you in understanding the phenomenon.
i attach the Cv curve how can we integrate the curve mean we integate all the loop or specfic area of the loop
At high current density and high scan rates, very few electrolye ions can occupy the spaces in the inner spaces of the electrodes which results into a decreased charge storage or capacitance.
This trend is because at slower scan rates or low current density electrolyte ions are entirely diffused into the electrode materials. Consequently, the entire active surface of the electrode material may be used for charge storage. In contrast, at faster scan rates, diffusion restricts the motion of electrolyte ions and only the the exterior active surface is used for charge storage.
Article Jute Sticks Derived and Commercially Available Activated Car...
Article Preparation of Sulfur‐doped Carbon for Supercapacitor Applic...
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