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Appendix

Figure 25.18: Contour Plot of Temperature (p. 858) shows a temperature hotspot in the internal shorted area of the battery cell.

5.Check for different electric current flow rates in the manner described in step 2.

a. Generate volume integral reports for the field variables listed in the table below.

Field Variable	Notation	Reported Value
Volumetric Short Current Source		15.844 A
Volumetric ECHEM Current Source		23.999 A

b. Verify that the total produced electric current equals to the sum of tab and short current, that is

.

6.Check for different types of heat generation rates.

a. As you did for the current source reports, generate reports for the field variables listed in the table below.

Field Variable	Notation	Reported Value
Volumetric Ohmic Source		0.0339 W
Electrochemistry Source		1.092 W
Short-Circuit Heat Source		64.607 W
Total Heat Generation Source		65.733 W

b. Verify that the total heat generation rate is the sum of different contributions, that is

.

Note that, as battery's temperature increases, thermal runaway may occur. If thermal runaway starts, some undesirable exothermic decomposition reactions will occur. For thermal runaway simulations, the default electrochemistry model cannot be used. Short treatment can only capture the thermal ramp-up process before the onset of thermal runaway.

25.5. Summary

In this tutorial, you studied how to solve a battery cell problem using the NTGK submodel with the default settings. You then used the ROM to speed up the computation time of the battery model simulation. In addition, you learned how to use the MSMD model capability to treat external and internal short-circuits.

For more information about using the Dual-Potential MSMD Battery model, see the Fluent Advanced Add-On Modules documentation.

25.6. Appendix

The battery cell cross-section is shown in the figure below.

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You can estimate the material properties for your battery cell using the following correlations:

• For density , heat capacity , and thermal conductivity :

where is the effective property value of a material property (such as density, heat capacity, or

thermal conductivity), is the thickness. The subscripts , , and refer to current collector, electrode, and separator, respectively. The superscripts and refer to positive and negative, respectively.

• For electric conductivity :

The material properties are taken from Kim’s papers [2] and [1]. The computed material properties for the battery cell presented in the tutorial are shown in the table below.

Zone								Total
[um]			20	150	12	145	10	322
[kg/m	3	]	2700	1500	1200	2500	8960	2092
[J/kg-K]			900	700	700	700	385	678
[W/m-K]			238	5	1	5	398	18.2
[s/m]			3.83e7	13.9		100	6.33e7	= 1.19e6
								= 9.83e5

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References

25.7. References

1.U. S. Kim et al,“Effect of electrode configuration on the thermal behavior of a lithium-polymer battery”, Journal of Power Sources, Volume 180 (2), pages 909-916, 2008.

2.U. S. Kim, et al.,“Modeling the Dependence of the Discharge Behavior of a Lithium-Ion Battery on the Environmental Temperature”, J. of Electrochemical Soc., Volume 158 (5), pages A611-A618, 2011.

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	Release 2019 R1 - © ANSYS,Inc.All rights reserved.- Contains proprietary and confidential information
862	of ANSYS, Inc. and its subsidiaries and affiliates.