What is the maximum temperature of a lithium battery when overloaded?

[electronium]

Greetings to the colleagues of the forum..
One point that has occupied my mind is, what is the temperature of the lithium battery when it is overloaded so that the battery is not damaged and we can get the maximum load from the desired battery?

 

[schmitt trigger]

I don’t think that there is such a specification. I have never seen one. All I have seen is maximum continuous current at 25C. I would then halve that value for every 10C temperature increment.

But you are asking about overload conditions. Now you are threading very treacherous waters. We don’t know what you mean exactly by “overload”. How much and for how long.
All I can say, as an experienced E-biker, that the battery fires I have seen have always been started by kludged batteries. Search YouTube for battery fires, they are literally frightening events.

 

[electronium]

I don’t think that there is such a specification. I have never seen one. All I have seen is maximum continuous current at 25C. I would then halve that value for every 10C temperature increment.

But you are asking about overload conditions. Now you are threading very treacherous waters. We don’t know what you mean exactly by “overload”. How much and for how long.
All I can say, as an experienced E-biker, that the battery fires I have seen have always been started by kludged batteries. Search YouTube for battery fires, they are literally frightening events.

For example, to a Nokia 5c or 3c mobile battery or 18650 battery
I connected a 120w lamp in front of the car, the battery lamp was getting warm, but it didn't get hot
The test continued until the discharge time and finally the lamp was turned off and the battery is empty

 

[ZipZapOuch]

The lithium battery's internal temp rise is along the path of greatest power loss from internal resistance. Since P=R*I^2, the path of least resistance is not where the power loss is the highest but, ultimately very close to it since the current is a square of resistance. In any case, the greatest power loss is near the center of the battery and, by the time you feel the heat, the electrolyte that allows the electrons to be mobile will have been damaged. Typically over 200°C for a very short period can damage the organic salts used as electrolytes. Newer (mostly still-under-development) solid electrolyte (or molten electrolytes) can handle higher temps because they are elemental (like sulfur) or high temp stable and cannot easily be damaged. In any case, your over current tests are ok but likely damaging some of the electrolyte or internal packaging materials and shortening the life of the battery. Manufacturers set a specification for a reason and they are unlikely to set an "ultra safe" specification that you should feel free to violate with no reprocutions on safety and/or battery life because, a battery manufacturer needs to claim all they can safely claim in terms of battery performance because their competitor is claiming all they can claim. The overly cautious company would quickly go out of business because engineers and consumers want the highest performance for their dollar.

In other words, be careful about your design - it is likely decreasing battery life even if you don't feel temperature rise. Also, check the manufacturers datasheet - even consumer batteries have one from a good company like Duracell and the like. The datasheet may have short burst over-current allowances in much the same way some LEDs can be pulsed way above their rated current.

 

[rjenkinsgb]

The maximum continuous temperature is typically around 60'C.

As ZZO says, if a cell or battery heats up quickly in use, then it's internal temperature may already be high enough to cause damage to the cell, by the time the heat gets through to the casing.

Also note that lithium cells degrade massively faster as the temperature increases - a cell with a lifetime of some years at 20'C may only last a few weeks at 60'C

If you need high currents, use more (matched) cells in parallel, or higher voltage plus a good buck converter to give the correct voltage for the load.
(That also gets around the voltage change between fully charged and near flat).