LEDSchlucker
Member
- Joined
- Dec 20, 2018
- Messages
- 157
Hi all,
I have 40 18650 which were 0V and I recovered all of them, the capacity is 3400mAh and the SD is ok.
So recently I stumbled over this Article:
Under-voltage / Over-discharge
Rechargeable Lithium cells suffer from under-voltage as well as over-voltage. Allowing the cell voltage to fall below about 2 Volts by over-discharging or storage for extended periods results in progressive breakdown of the electrode materials.
Now, do I have to worry about that? And should I not use the Cells for my Powerwall?
If anyone has experience with recovered low voltage cells please tell me what you suggest.
And, am I right with that, a fully charged cell which gets a internal short circuit, will probably end in a thermal runaway?
Best Regards
LEDSchlucker
I have 40 18650 which were 0V and I recovered all of them, the capacity is 3400mAh and the SD is ok.
So recently I stumbled over this Article:
Under-voltage / Over-discharge
Rechargeable Lithium cells suffer from under-voltage as well as over-voltage. Allowing the cell voltage to fall below about 2 Volts by over-discharging or storage for extended periods results in progressive breakdown of the electrode materials.
- Anodes
First the anode copper current collector is dissolved into the electrolyte. This increases the self discharge rate of the cell however, as the voltage is increased again above 2 volts, the copper ions which are dispersed throughout the electrolyte are precipitated as metallic copper wherever they happen to be, not necessarily back on the current collector foil. This is a dangerous situation which can ultimately cause a short circuit between the electrodes.
- Cathodes
Keeping the cells for prolonged periods at voltages below 2 Volts results in the gradual breakdown of the cathode over many cycles with the release of Oxygen by the Lithium Cobalt Oxide and Lithium Manganese Oxide cathodes and a consequent permanent capacity loss. With Lithium Iron Phosphate cells this can happen over a few cycles .
Now, do I have to worry about that? And should I not use the Cells for my Powerwall?
If anyone has experience with recovered low voltage cells please tell me what you suggest.
And, am I right with that, a fully charged cell which gets a internal short circuit, will probably end in a thermal runaway?
Best Regards
LEDSchlucker