Hi,
I have prepared a set of thin film electrodes for supercapacitor applications,
All the electrodes were prepared at different substrate temperatures (373 K to 673 K), in this I have got the specific capacitance values around 100 F/g (373 K sample), 180 F/g (473 K samples), 230 F/g (573 K sample) and the 190 F/g (673 K sample), here we notice that the capacitance values are gradually increasing up to 573 K and the suddenly decreasing at higher temperature (673 K sample),
Here in this case i have an doubt on WHY THE CAPACITANCE VALUE IS DECREASING AT HIGHER TEMPERATURE ..?
Dear researchers kindly give me the possible reasons for my question.
Thank you.
Dear Durai Govindarajan
is your sample porous ??? do you have any other experimental evidence such as BET, surface acoustic wave devices data and ,AFM?? if there kindly look into the surface area and porosity ..... and in the above case I think, initially increasing the processing temperature leads to enhanced active site/surface area which might assist to obtain the enhanced capacity, then the material prepared at 673 K may undergo sudden structural change or consist of less active site This might lead to decrease in capacity
Dear Gnanavel Angamuthu,
Thanks for your valuable answer on my question.
The electrode is a kind of thin film electrode, for structural and morphology studies I have taken XRD and FE-SEM investigations. From FE-SEM analysis I can see the structural changes but apart from the structural changes, Is there any specific reason ..?
Please give me your answer Bro..?
I think BET is not applicable for measuring surface area of the thin films.
Dear Prof. Artur Braun ,
Thank you for your answer,
All the elctrochemical studies were carried out at ambient temperature with KOH electrolyte.
Here, I have prepared the thin film electrodes at different substrate temperatures (373 K to 673 K), in that 573 K prepared sample only showing decreasing capacitance than 673 K sample.
Durai Govindarajan
Yah it is difficult in case of BET but some of the researchers discussed in the following link ...pls go through it and u may get some idea
Article Determination of BET Surface Areas of Porous Thin Films Usin...
https://www.researchgate.net/post/Is_it_possible_to_do_the_BET_measurement_on_thin_film_thick_ness_is_300-400_nm_for_effective_surface_area_of_the_sample
https://www.researchgate.net/post/Why_does_Krypton_work_better_than_N2_or_Ar_for_BET_surface_area_measurement_of_porous_thin_films
Dear Gnanavel Angamuthu,
Thank you for your answer with references.
This is a difficult question because a large number of parameters influence the quality of the electrodes and therefore the capacitance. It is possible in your case that above 573K, the quality of the electrode decreases (by a different crystallization or a different interfacial capacity). It is common that the electrode conditions of elaboration influence the capacitance values.
- Badges
- Science topic
- Similar topics
- Chemistry
- Nanotechnology
- Nanostructures
- Thin Films