I'm making an electrode for supercapacitor electrode and I have searched PTFE is a better binder than PVDF. I would like to know why. Thank you.
The choice of electrolyte depends on your application. As far as i know you should get a higher specific capacitance for KOH electrolyte than for H2SO4. But i am not an expert on supercapacitors. So please cross check this information with the literature.
If you want to use KOH u will have to use PTFE as binder, because PVDF will strongly degrade in alkaline environment via dehydroflurination. Besides degrading the polymer it will split "HF" (or fluoride ions) from the PVDF backbone, which will eventually cause damage to your electrode. If you want to use H2SO4 i dont see any problems with PVDF as binder. As PVDF is soluble in many aprotic solvents (e.g. N-1-Methyl-2-pyrrolidone) it is easy to make an ink from it. For PTFE you will have to use a PTFE dispersion (most commonly in water).
@Juan Casado >> Can you explain more specific, please? Or any thesis I can make a reference or to study?
You can try to find articles talking about the reactivity and stability of PVDF first...
e.g. PVDF isn't stable in alkaline environment due to dehydroflurination
@Tilman Jurzinsky >> Oh i see. But I'm using 1M H2So4 as electrolyte. A lot of thesis they use H2SO4 or KOH. I was confusing which one to use, my sample is PANI coated graphene. Which one should I use as electrolyte? I will be very very glad if you could answer or some articles i can read , I have a meeting with my professor and I really should give him a answer.
THanks !!
The choice of electrolyte depends on your application. As far as i know you should get a higher specific capacitance for KOH electrolyte than for H2SO4. But i am not an expert on supercapacitors. So please cross check this information with the literature.
If you want to use KOH u will have to use PTFE as binder, because PVDF will strongly degrade in alkaline environment via dehydroflurination. Besides degrading the polymer it will split "HF" (or fluoride ions) from the PVDF backbone, which will eventually cause damage to your electrode. If you want to use H2SO4 i dont see any problems with PVDF as binder. As PVDF is soluble in many aprotic solvents (e.g. N-1-Methyl-2-pyrrolidone) it is easy to make an ink from it. For PTFE you will have to use a PTFE dispersion (most commonly in water).
@Tilman Turzinsky >> Thank you! I will double check. Your suggestions were very helpful ! :D
In agreement with Tilman, please notice that no problems are expected for PTFE as binder, either in acid or basic media, due to its superior stability...
PTFE -poly tetra fluro ethylene and pvdf -poly vinylydene fluoride both are polymers used for hydrophobic property of the electrode to avoid from flooding of the cathode material( carbon cloth).Mostly in studies they are using PTFE solution then other type of solution....If you want to try with new type of polymer? you can try.
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