Abstract

The temperature and heat produced by lithium-ion (Li-ion) batteries in electric and hybrid vehicles is an important field of investigation as it determines the power, performance, and cycle life of the battery pack. This paper presented both laboratory data and simulation results at C-rates of 1C, 2C, 3C, and 4C at an ambient temperature of approximately 23 °C. During experiment thermocouples were placed on the surface of the battery. The thermal model assumed constant current discharge and was experimentally validated. It was observed that temperature increased with C-rates at both the surface and the tabs. We note that at 4C the battery temperature increased from 22 °C to 47.40 °C and the tab temperature increased from 22 °C to 52.94 °C. Overall, the simulation results showed that more heat was produced in the cathode than the anode, the primary source of heat was the electrolyte resistance, and the battery temperature was the highest near the tabs and in the internal space of the battery. Simulation of the lithium concentration within the battery showed that the lithium concentration was more uniform in the anode than in the cathode. These results can help the accurate thermal design and thermal management of Li-ion batteries.

Highlights

  • In the US, 28% of greenhouse gas emissions are from the transportation sector

  • Thermoelectric devices are advanced technology but have a high energy requirement. Passive cooling systems such as Phase change materials and heat pipes allow for decreased energy usage increasing vehicle range and as such need to be investigated as thermal management solutions in electric vehicles

  • The model is a great fit to the experimental data and high discharge rates the cell voltage deviates significantly from the open circuit potential (OCP) due to Ohmic, activation, and demonstrates the robustness and accuracy of the model as both the average surface temperature and mass transport losses, and a larger overpotential is observed

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Summary

Introduction

In the US, 28% of greenhouse gas emissions are from the transportation sector. Electric vehicles (EVs) are a critical measure in reducing emissions. Irreversible heat generation due to ohmic resistance, charge transfer, and mass transfer losses are investigated along with the reversible heat These heat generation terms from the cathode are determined from electrochemical measurements and are modeled as functions of the C-rate, temperature, and lithium concentration in the active material. Thermoelectric devices are advanced technology but have a high energy requirement Passive cooling systems such as Phase change materials and heat pipes allow for decreased energy usage increasing vehicle range and as such need to be investigated as thermal management solutions in electric vehicles. Battery modeling is presented below: Patil et al [14] investigated the cooling performance of cold plates on a 20 Ah Li-ion pouch cell. Shah et al [16] investigated the steady-state temperature profiles in convectively cooled cylindrical Li-ion cells operating at high discharge rates.

Procedure
LiFePO
Parameters used for model
20 Ahthe prismatic cell atare
20 Ah-LiFePO is identicaltotothe the experimental battery and its
Governing Equations and Boundary Conditions
Governing Equations in the Electrolyte
Porous Electrodes
Energy Equation
Results and Discussion
Surface
Comparison
Temperature
11. Temperature
We this maximum
Conclusions
Full Text
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