Hi Pranjala，

Please give the detail of the metallic foam, electrolyte and the working voltage window of your supercapacitor.

The working voltage window is not only depend on the active material but also depend on the metallic foam and electrolyte. The wrong working voltage window may lead to the decomposition of the electrolyte or the irreversible reaction on the surface of the current collector (e.g., ORR). All of these can result in a high and irreversible "fake capacitance" and poor cycling performance. Moreover, some gas generated from the reversible reaction may also cause the detachment of the active material from the current collector, which also lead to the poor cycling performance.

Hello Pranjala Tiwari

It depends on the nature of the electrolyte. you haven't mentioned about your selected electrolyte. If you are using any alkaline electrolyte, then there is a sure chance to metal hydroxide during electrochemical reactions. For example, If you have use Ni foam in any alkaline electrolyte, then It will form Ni (OH)2 during electrochemical process. This can be the origin of the unstable behavior. you can check the attached file.

Moreover, metal sulfides generally suffers from poor stability. The best option to increase the stability is to prepare composite with carbon based materials(MWCNTs, rGO).

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Dear all,

Thanks alot for your valuable responses.

I have used both Copper foam as well as Nickel foam in the voltage window of -0.7 V to -0.2 V. And the electrolyte is 0.5M Na2SO4. Moreover, i have gone through the literature, this electrolyte being neutral in nature remains stable in this potential window.

I agree with the fact that metal sulfides do suffer from poor stability and adhesion problems. However, i was expecting that 3D porous nature of metallic foam could provide structural stability to my active material. But instead, the stability was worse than that on ITO substrate.

Hello pranjala,

Use of Copper as substrate forms Copper sulphate in sodium sulphate electrolyte. You should use steel as current collector, it may help.