Actual composition of NiCd batteries
I started thread about NiCd batteries a few month ago and nothing more was posted in it.
I decided to start new thread because previous one got rather old. I should post this in old thread sorry in advance but i am not sure about customs
in this forum.
I have disassembled one old and dead NiCd cell. Voltage on it was 0 (checked with voltmeter) And on electrode i noticed trace of greenish dirt.
Cell was made of metal cup that i have to cut to open it. Inside i have found rolled paper strip with black paste (that was rather dry due to age of
cell).
I was unable to identify what is anode and what is cathode.
I'm confused. NiCd cell (discharged) should be made of nickel(II) hydroxide and cadmium hydroxide. Nickel(II) hydroxide is greenish and cadmium
hydroxide is white.
I found black substance.
When i putted drop of household vinegar (i did not had any better acid at this time a hand)
i noticed evolution of gas without colour nor smell. Not everything got dissolved.
Has anyone idea what this can be? How i can identify composition of this substance?
I can dissolve this paste in acid, neutralize solution and use dimethylglyoxime to check for presence of nickel. But how to check for presence of
cadmium other that by trying to precipitate yellow cadmium sulfate?
Also any ideas how to separate this two metals? I can dissolve everything and precipitate nickel and cadmium on electrodes in process similar to
electrolytic purification of copper.
Or add excess NaOH to complex cadmium filter, then add acid to solid substance that was left, dissolve in acid and then get nickel on electrode.
Thanks in advance for any information or references.
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