When you read about it, you’ll learn that the average lithium battery can take about 300-500 charge cycles before its considered worn out. What exactly changes inside the battery for it to reach a worn out status?
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Ok so super ELI5.
You have a lithium substance on one side, usually a carbon substance on the other side, and some transfer medium liquid like stuff in the middle.
When you use the battery, lithium atoms float from the lithium side over to the carbon side.
When you recharge the battery the lithium atoms go back.
The power of the battery is in how far the atoms move before they hit the other side, but the issue is that when you recharge the battery, there is no knowing where the lithium atoms will pile up back on the lithium side. So eventually little mounds start to appear, and these end up a tiny bit closer to the carbon side than before. Which then attracts more lithium.
You do the discharge, recharge cycle enough, and those little mounds turn into relative mountains which stretch across the transfer substance and can even touch the carbon on the other side. Effectively shorting out the battery.
As the mountains are building up, the potential energy of the battery is reducing.
This is why they tell you that it is not the use of the battery that uses it up, its how many cycles you put on it.
If you could go into the battery and squeegee those mountains back down, without destroying the battery, you could effectively recycle it.
Basically this happens [https://www.youtube.com/watch?v=n0jy6uVjRFQ](https://www.youtube.com/watch?v=n0jy6uVjRFQ) except much slower, with lithium and in the battery electrolyte. That that sort of dendritic growth is of course bad because it will first reduce battery capacity and eventually short the battery.
I would say the rule of thumb is more like 1000X full cycles, but it’s a bit of a line in the sand because it depends on how deep the typical charge/discharge cycle is, how high the current is and of course, at what point of degradation is the battery considered no good anymore.
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The liquidy substance inside the battery that facilitates the flow of elections can build up deposits that limit the flow of electrons. That’s about as simple as it can be explained.
Ever hear of electroplating? It’s what we use to do things like plate gold or other metals onto a cheaper metal. We do this all the time for things like for USB plugs. The wire contacts tend to be plated with gold or other corrosive resistant conductive metal.
Chemical batteries work kinda similar to this. You have 2 conductive materials, the + and – sides of the battery. The battery chemistry is basically like the chemical bath used for electroplating.
As you discharge the battery, usually some metal will start to “plate” (modern batteries actually use a sponge-like electrode that absorbs the metal) on one of the electrodes. When charging, this gets reversed and the plated metal dissolves into the electrolyte. In lithium batteries this is the lithium in the electrolyte. The specific type of lithium battery will have different makeups for the electrolyte, but lithium is usually the metal that gets “plated”.
The problem is that over time this process isn’t perfect. The chemicals in the electrolyte eventually wears down. When you fully charge/discharge lithium batteries some of the lithium winds up “stuck” forming spikes of lithium metal that don’t really dissolve back into the electrolyte when you recharge it. Less free lithium in the electrolyte means that it can hold less charge. This is the main reason why lithium batteries wear down. We haven’t really figured out a good way to reverse this buildup yet, although there is a lot of research into it and some promising results in recent years.
Eventually, after enough time, the spikes might create a connection between the electrodes forming a short circuit. At this point the battery is dead and can be very dangerous to recharge because the short circuit just causes the battery to heat up and explode instead of reversing the chemical reaction. Lithium batteries compared to other chemistries (like lead acid batteries) are especially prone to this kind of failure.
Can someone please expand: why do they say lithium batteries won’t leak whereas other batteries will leak
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