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zinc battery info needed

Discussion in 'Electronic Projects Design/Ideas/Reviews' started by cobra1, Dec 24, 2009.

  1. cobra1

    cobra1 New Member

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    hi

    im currently working on a project that uses zinc as an anode and tungsten as a cathode, the medium is an aqueous solution of sodium hydroxide

    solution is 10g NaOH to 100ml water (not sure what this equates to in terms of strength)

    now my question is, why does this setup create a voltage potential when measured across the 2 metals??

    and is there anyway to make it stronger without adjusting the Naoh concentration??

    i am currently getting about 0.8v @ 40ma ocross the 2 metals
     
  2. jpanhalt

    jpanhalt Well-Known Member Most Helpful Member

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    I think you may be building a zinc-air battery and have substituted tungsten for the usual carbon or other inert conductor as the cathode.

    Can you provide a reference for your design?

    The approximate molarity of your NaOH solution is 2.5 molar.

    You get voltage because the zinc is being oxidized (i.e., it releases an electron). Whatever accepts that electron completes the electrochemical cell. If it is oxygen, you should get a no load voltage of about 1.65 volts. Under load, that potential will be less due to internal resistance in the cell.

    My CRC Handbook does not show any reactions for reduction of tungsten; although, Wikipedia shows two possible negative valences. They may be quite unstable in water, just like hydrides are.

    If you can confirm that the electron acceptor is not oxygen, but rather is tungsten, I will research it some more.

    John
     
  3. cobra1

    cobra1 New Member

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    jpanhalt thanks for the reply,

    this is used for the production of hydrogen, when the zinc and tungston electrodes are connected with a peice of wire then hydrogen is produced from the tungston carbide electrodes.

    i realise that the zinc does oxidize over time, but i have found a way to regenereate this zinc electrode on the fly. so the production of hydrogen can occour for far longer than it would under normal circumstances, the zinc electrode does become choked up with zincates after about 500 - 700 hours or so running time.
     
  4. dave

    Dave New Member

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  5. Sceadwian

    Sceadwian Banned

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    The zincates are probably only on the surface, so if the electrodes are thick enough you can scrape/grind the surface down and reuse them. Also to make the available current higher you can use perforated or corrugated electrodes, the amount of reaction taking place is directly related to the surface area of the electrodes.
     
  6. cobra1

    cobra1 New Member

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    Have had this idea, the idea goes like this,

    one chamber with zinc in it, (anode). another chamber with stainless steel in it (cathodes)

    fill the cell up with aquaeus solution of NaOH and add colloidal silver

    normally the anode and cathode would be connected through the solution, since the silver gives the water higher conductivity for elecricity to flow it got me thinking. when measuring the voltage potential between zinc and stainless steel electrodes you should get voltage

    could the 2 electrodes be seperated by a metal plate. so we have 2 totally isolated electrodes that are still in contact with each other electrically????

    would i still get the same voltage potential between the electrodes??

    any suggestions
     
  7. Sceadwian

    Sceadwian Banned

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    No, the transfer of energy is actually from the conversion of the chemicals from one form to another through the fluid electrolyte between the plates, no reaction can take place in the electrolyte if they're separated. Metal plates allow electrons to flow, they do NOT allow ionic fluids to flow.

    Voltaic cells are the magical borderline between electronics and chemistry. Not easy for someone based in electronics to understand, they're very different fields, however they do share some similiarities. Mainly because electrons play a major roll in virtually all chemical reactions.
     
    Last edited: Dec 27, 2009

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