Why do alkaline batteries lose their capacity after 50 times of recharging?

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Discussion Overview

The discussion revolves around the capacity loss of alkaline batteries after multiple recharges, exploring the underlying chemical processes and comparing them to lithium batteries. Participants examine the reasons for capacity degradation, including corrosion and side reactions, while questioning the differences in longevity between battery types.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants note that corrosion leads to unwanted reactions, affecting the battery's capacity.
  • There is mention of a standard reduction potential difference that facilitates electron flow, but this flow can also involve undesired reactions with external species like water.
  • One participant suggests that charging can restore some of the corroded ions, implying that the battery can function similarly to its original state.
  • Another participant argues that if charging fully restored the battery, it would eliminate the need for purchasing new rechargeable batteries, indicating that some ions are lost externally, forming precipitates with reactants from the environment.
  • Questions arise regarding the difference in rechargeability between alkaline and lithium batteries, with one participant suggesting that lower voltage batteries tend to last longer due to the rates of unwanted side reactions.
  • There is a discussion about how the voltage of a battery relates to its reactivity and the longevity of its charge cycles.

Areas of Agreement / Disagreement

Participants express differing views on the mechanisms behind capacity loss in alkaline batteries and the comparison with lithium batteries. The discussion remains unresolved, with multiple competing explanations and no consensus reached.

Contextual Notes

Participants reference various chemical processes and external factors affecting battery performance, but the discussion does not clarify specific assumptions or definitions regarding battery chemistry.

Physicsissuef
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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:
http://www.afrotechmods.com/reallycheap/batteries/batts.htm"
http://www.allaboutbatteries.com/Alkaline-charging.html"
 
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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.
 
Jax said:
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.
but with the charger I get back the ions that have corroded so the battery is working same like on the start.
 
Physicsissuef said:
but with the charger I get back the ions that have corroded so the battery is working same like on the start.

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).
 
Jax said:
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).
But why alkaline battery can be charged for about hundred times, and lithium battery 2 years? What is the difference?
 
Physicsissuef said:
But why alkaline battery can be charged for about hundred times, and lithium battery 2 years? What is the difference?

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.
 
Jax said:
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).
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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