1) The document discusses the influence of low temperature conditions on lithium-ion batteries. Low temperatures below 25°C can significantly reduce battery power and accelerate capacity decay. 2) Experiments were conducted on Samsung 18650 batteries between 0-25°C to analyze changes in voltage, capacity, and surface temperature under low temperature conditions. Mathematical models were also developed to analyze heat generation within batteries. 3) The results showed that low temperatures restrain electrochemical reactions and increase internal resistance in batteries. Low temperatures also cause uneven temperature distribution and deteriorate temperature uniformity within batteries.

1. 西南科技大学
Influence of low temperature
conditions on lithium-ion batteries
Reported by：Ratul
A review of: Influence of low temperature conditions on lithium-
ion batteries and the application of an insulation material;
Dongxu Ouyang et al; DOI: 10.1039/C9RA00490D

2. 西南科技大学
• Battery working environment
• Low temperature environment
• Calculation of low temperature influence
• Mathematical analysis of heat generation
• Capacity decay for low temperature condition.
Table of content

3. 西南科技大学
Lithium ion battery working
environment
The working environments of LIBs are complex. There are
many extreme conditions are related with LIBs working
environment, such as
• External forces,
• High temperature,
• Low temperature,
• Overcharge and over-discharge

4. 西南科技大学
Lithium ion battery working
environment
Among all working conditions the low temperature condition
cause significant loss of battery power and accelerate the
capacity decay rate, which dramatically limits the driving range
and hinders the expansion of EVs.
What is the low temperature environment?
• The low temperature environment of lithium ion battery is the
temperature range of 0–25C

5. 西南科技大学
Calculation of low temperature
influence
The core strategy of exploring the influence of low temperature
on lithium ion battery is experiments the battery parameters
such as voltage, capacity and surface temperature on a
temperature range of 0-25C.
Sample battery: Samsung 18650
Capacity : 1300 mAh
Charge cut-off voltage : 4.2 V
Discharge cut-off voltage : 2.75 v
Battery anode: Graphite

6. 西南科技大学
Experiment setup

7. 西南科技大学
Heat generation within the battery is mainly composed of
chemical reaction heat and Joule heat, expressed by the
following equations,
gen chem Jq q q   
exp( ) ( )a
gen n OC t
b
E
q HM A I U U
RT
     
where is the reaction heat, M is the mass of reactants, n is
the reaction order, A is the pre-exponential factor, Ea is the
activation energy, R is the gas constant, Tb is the battery
temperature, I is the current, UOC is the open circuit voltage and
Ut is the terminal voltage.
H
Mathematical analysis of
heat generation

8. 西南科技大学
Generally, heat release by the battery is via heat convection by
air, which can be expressed as follows:
cov ( )b airq hA T T  
where h is the convective heat transfer coefficient, A is the
battery surface area, and Tair is the ambient temperature.
If the temperature distribution within the battery is uniform, then
the temperature variation of the battery can expressed as,
exp( ) ( ) ( )b a
n OC t b air
b
T E
C HM A I U U hA T T
t RT


      

where p is the density of the battery, C is the specific heat, and
t is the time.

9. 西南科技大学
Temperature rise curves of the batteries at low and normal temperature and at
different cycle rates.
The solid lines representing the low temperature conditions
(0C) and dotted lines the normal conditions (20C).

10. 西南科技大学
It shows that,
• The low temperature conditions evidently influenced the
cycle time of the LIBs.
• Compared to the normal conditions, the cycling processes of
the LIBs were much slower under low temperature
conditions.
That means, the electrochemical reactions inside the batteries
were restrained by the low temperature, and meanwhile, the
internal resistance increased. So that the internal resistance of
the battery became larger at low temperature.

11. 西南科技大学
The curves of the temperature differences within a single battery at low and normal
temperature and at different cycle rates.
This figure shows the surface temperature differences of
batteries during cycling at cycle rates of 1C, 2C, and 3C, and
ambient temperatures of 0C and 20C, respectively.

12. 西南科技大学
For a fixed cycle rate if the pick value of temperature rise at 0C
and 20C compared, the results will indicate that the uniformity
of battery surface temperature is deteriorated by low
temperature, which led to uneven temperature distribution
within the battery.
Moreover it is crucial to maintain good uniformity among the
LIBs in a application where large numbers of LIBs are
connected in series or parallel.

13. 西南科技大学
The capacity decay curves of batteries as a function of cycle number: normal
temperature, 20C.
Capacity decay for low
temperature condition

14. 西南科技大学
At normal temperature, it took several cycles to activate the
battery, which is exhibited as the initial rise in capacity, which
then fluctuated around a critical value.
N.B. Typically, the lower the cycle rate, the greater the
capacity.

15. 西南科技大学
The capacity decay curves of batteries as a function of cycle number: low
temperature, 0C

16. 西南科技大学
Under the low temperature conditions, it can be observed that
as the cycle number increased, the battery capacity decayed
gradually at rates of 0.046, 0.053 and 0.074% per cycle,
respectively.
This reveals that low temperature aggravated the aging of the
battery, the severity of which increased with increasing cycle
rate.
This result is related to the damage of the electrode and
separator structure.

17. 西南科技大学
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• ratul@mails.swust.edu.cn
• https://www.quora.com/profile/Ratul-26
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