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Alkaline battery question

  1. Jan 4, 2008 #1
    I read a lot of articles where says that alkaline batteries can be recharged, but it also says that they lose their capacity after 50 times of recharging? What makes them lose their capacity after 50 times of recharging?

    Here are some articles:
    afroman's article
    allaboutbatteries
     
  2. jcsd
  3. Jan 4, 2008 #2

    Jax

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    Corrosion causing unwanted reactions. A standard reduction potential difference exists that results in voltage from the electron flow from anode to cathode. However, this electron flow is not limited to simply anode/cathode as a species such as H20 can also react and you can have undesired side reactions happening on the surface of the battery.
     
  4. Jan 4, 2008 #3
    but with the charger I get back the ions that have corroded so the battery is working same like on the start.
     
  5. Jan 4, 2008 #4

    Jax

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    If this were the case then you could keep using the same battery and you would never have to buy another rechargeable battery. Some of your ions are lost, not on the inside of the battery, but on the outside surface. They can form various precipitates with other reactants that didn't come originally from the battery (such as from the air).
     
  6. Jan 4, 2008 #5
    But why alkaline battery can be charged for about hundred times, and lithium battery 2 years? What is the difference?
     
  7. Jan 4, 2008 #6

    Jax

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    Lower voltage batteries tend to last longer. Voltage means Joule/Coloumb, how badly electrons want to flow; higher voltage means more reactive (and we harness the spontaneity of the reactions). A car battery is much higher voltage but when the car's on the alternator also forces it to run in reverse to recharge it every time.

    It's all about rates, how fast does an unwanted side reaction occur and how much do we have in metal reserves before there's no more electron flow.
     
  8. Jan 4, 2008 #7
    You mean that some of the reactants reacted with air, and they are lost on the outside surface of the battery, not in the battery?
     
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