3

What can be done to repair or restore an ageing/dead/failing Li-ion rechargeable battery?

As they get older; they typically, gradually lose their capacity to hold a charge. What physical and/or chemical differences are there between new and old?

voices
  • 1,069
  • 1
  • 15
  • 30
  • 1
    Recycle, replace. They ain't NiCads and many of the nicad tricks were of very limited benefit. But nicads were not (or at least not very) prone to explosions/fires... – Ecnerwal Sep 29 '16 at 19:58
  • Lithium based cells wear out through usage and age. There is no way to rejuvenate them. – Bimpelrekkie Sep 29 '16 at 20:10
  • So the actual internal physical structures literally collapse and disintegrate? – voices Sep 29 '16 at 22:55
  • I believe the microstructure of the anode degrades, which reduces the rate at which the electrochemical reaction occurs: translation, series resistance increases. There are also other effects which can cause electrolyte loss, I believe. This is also irreversible, and causes permanent capacity loss. As other say, you can't really rejuvenate a used-up lithium cell. – user57037 Sep 30 '16 at 00:40

2 Answers2

2

While there are certainly design and maintenance practices that can help to prevent or slow degradation, there's not really any practical way to repair degradation that has already happened to a given cell.

However, often a battery is made from multiple cells. And it's often practical to find out which of those are the weakest in terms of reduced capacity and higher internal resistance. If they're in series, the weakest cell will determine the effective capacity of the whole pack. So you can replace just the weak cells to rejuvenate the battery as a whole. Or, since typically the cells are much cheaper than the pack as a whole, just replace all of them.

Be careful, this can be quite hazardous - be sure to research how to do it safely before attempting!

pericynthion
  • 6,174
  • 20
  • 34
1

Store them at low temperature to prevent degradation. 4 to 16C would be quite good and easy to maintain. For good Li-ion batteries, there should be a stored capacity decrease of under 4% per year with no practical degradation of the cell.

For recovering damaged ones that have been in extensive use(and have various problems like being unable to sustain the specified current), low temperature also helps. Keep them at near-zero degrees C temperature for a few minutes and then recharge them without any optimization (like this phones use - if it's a phone, charge it while the phone is turned off).

For the old vs new issue, after years of determinations I can safely conclude that older ones are better at keeping their capacity intact over the years.

I still have 2000 mAh cells from the times the 2200mAh ones were the best available. Compared to them, the 2600 ones and above are very quick to reduce capacity.

Note that capacity damage is irreversible. I mean you will be able to recover li-ion that has not been used for years and still have a good chance of being able to use most-to-all of the capacity, but you can't do much for the ones that have reduced capacity due to extensive wear.

Overmind
  • 480
  • 4
  • 9