Hi there
Why are metal oxides used as positive electrode? Is there any theoretical explanation? I also see that there are papers on using Iron as negative to improve the voltage window[Emperically I see its true from their papers]!
Please let me know the "actual" electrochemistry behind this.
thanks
For an asymmetric/hybrid supercapacitor. Metal oxides don't easy to be oxidized and it is used as anode electrode. Carobn and iron dont easy to be reduced and it is used as cathode electrode.
Iron and carbon don't easy reduction used as cathode, metal oxides don't easy oxidation used as anode.
Dear Sridhar
the "actual physics" behind this is:
the chemical potential uei of both the
1. electrons (ue) and
2. (intercalated) ions (ui)
So, uei (=ue+ui) is suitable for many practical cell-systems for batteries and supercapacitors. The combination of high ue values in oxides is attractive, as well as, the high (mostly for batteries) density of e-states in TMO, due to TM (https://en.wikipedia.org/wiki/Transition_metal#Variable_oxidation_states).
In many practical cases the ui is small (abs(ui)
For an asymmetric/hybrid supercapacitor. Metal oxides don't easy to be oxidized and it is used as anode electrode. Carobn and iron dont easy to be reduced and it is used as cathode electrode.
Dr. Chen
Cathod is the positive electrode during discharge, isn't it? And moreover, just like iron other transition metals also tend to oxidise rather than reducing.?! Could you please explain?
regards
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