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I'm an engineering student preparing for my graduation, in one step of my graduation project I used a rechargeable battery(1.2 volt), i was shocked when this battery is starting to recharge it self until it reach 1.04 volt (not fully) for many many cycles and immediately when the voltmeter reads 0 volt from it, when i asked my doctors they told me that maybe its chemical issue.

so is there any explanations please?

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    $\begingroup$ It depends on how it was discharged. Most batteries will recover (somewhat) and have a higher voltage after a rapid discharge. When the battery is in use, the internal resistance increases with a high discharge rate. When the battery is removed from the circuit, the internal resistance recovers. The internal resistance has a dependence on ion flow, concentrations, interactions at the electrodes and the redox reaction (there may be others). $\endgroup$ – LDC3 Aug 2 '15 at 13:59
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As the comment indicated, it is probably equilibrating. When you are discharging the battery, you are causing the materials in the electrodes and the electrolyte to rearrange. The surface of the electrodes are where the reactions are happening, so the products of the discharge reactions tend to accumulate at or near the surfaces of electrodes. This causes the measured potential to go lower.

Once the discharge stops, the contents start to homogenize within the cell bringing the discharge products away from the electrodes and bringing the material from the charged state closer to the electrodes. This in turn increases the measured potential.

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  • $\begingroup$ thank you very useful . but please how much times this cycle will repeat ? $\endgroup$ – jumana haimour Aug 4 '15 at 18:26
  • $\begingroup$ Not sure what you mean by how much. This will happen every time you discharge or charge with significant current. If you are asking how long this relaxation will take, that depends on a lot of parameters including the SOC, SOH, viscosity of the electrodes, diffusion rate of the electrolyte ions etc... $\endgroup$ – Burak Ulgut Aug 5 '15 at 6:45
  • $\begingroup$ thank you a lot :) but please can you give me a paper name or a book name that illustrates this that i can study , because i have to mention this in details on my graduation project documentation , i'm an electrical engineering so i don't have a good background about this :( $\endgroup$ – jumana haimour Aug 6 '15 at 18:09
  • $\begingroup$ Your best bet is to read basic electrochemistry books like Bard&Faulkner, particularly chapters explaining concentration gradients and controlled current experiments. I don't know of any specific document applying that to batteries. $\endgroup$ – Burak Ulgut Aug 7 '15 at 8:28

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