I validated Lion 26650 battery data against 2RC equivalent circuit model. The RMSE seems to improve with high temeparature ie good results for 50 deg, then 25 deg and 0 deg had bad results. What is the reason ? Any literature or ref will be useful to add in my writing
Thanks,
Praveen
Hello,
There's plenty of literature talking about this fact. Just put Teffect on Li-ion batteries and wou'll get plenty of explanations. Or take a look at the reviews by Barre et al or Wetter et al.
It happens that the active tension increases with high temperature, as it gets worse in below 0ºC. Did you ever notice that your mobile phone battery capacity decreases sensitively when going to sky in winter? Then, If you take your mobile phone and warm it back in the hotel it will recover part of the capacity.
The "electric" reason is found in the internal resistance of the battery. As the Resistance decreases with heat, there are fewer losses, the efficiency improves and the voltage drop is reduced, thus, you have more "available" capacity.
I suppose that your model takes look-up tables for R and C values. You'll surely see that the values of R will decrease at hot temperatures and increase at low temperatures as Alex Friesen suggests.
Moreover, it goes inversely for battery ageing, high temperatures accelerate ageing and cold temperatures normally increase the lifespan following an arhenius courve.
Hope this helps.
Lluc
Higher temperatures increase the conductivity of Li+ in the electrolyte, the anode and the cathode. This means, your total resistance will decrease with increasing temperature. Lower resistances results in lower overpotentials, which in turn allows you to use more lithium in the chosen voltage window of your LIB.
Vice versa, lower temperatures will increase overpotentials, this might lead to unwanted aging effects in LIBs.
Check for literature arrhenius behavior of electrolytes, Li+ solid state diffusion
In my opinion, the simplest explanation is that the rise in temperature leads to an increase in the number of electrically charged ions for time unit.
When measured, this would seem like increasing of the conductivity of Li + in the electrolyte.
I think this is typical of most batteries.
Because the model is sensitive to the temperature I suppose.
http://www.a123systems.com/Collateral/Documents/English-US/A123%20Systems%20ANR26650%20Data%20Sheet.pdf
you can check here, the different temperature will generate different discharge performances.
Hello,
There's plenty of literature talking about this fact. Just put Teffect on Li-ion batteries and wou'll get plenty of explanations. Or take a look at the reviews by Barre et al or Wetter et al.
It happens that the active tension increases with high temperature, as it gets worse in below 0ºC. Did you ever notice that your mobile phone battery capacity decreases sensitively when going to sky in winter? Then, If you take your mobile phone and warm it back in the hotel it will recover part of the capacity.
The "electric" reason is found in the internal resistance of the battery. As the Resistance decreases with heat, there are fewer losses, the efficiency improves and the voltage drop is reduced, thus, you have more "available" capacity.
I suppose that your model takes look-up tables for R and C values. You'll surely see that the values of R will decrease at hot temperatures and increase at low temperatures as Alex Friesen suggests.
Moreover, it goes inversely for battery ageing, high temperatures accelerate ageing and cold temperatures normally increase the lifespan following an arhenius courve.
Hope this helps.
Lluc
Hi,
May it help you:
https://doi.org/10.1016/j.jpowsour.2010.08.070
--Anafi
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