Thermal behavior of small lithium-ion battery during rapid charge and discharge cycles

doi:10.1016/j.jpowsour.2005.08.049

Journal of Power Sources

Volume 158, Issue 1, 14 July 2006, Pages 535-542

https://doi.org/10.1016/j.jpowsour.2005.08.049 Get rights and content

Abstract

The secondary batteries for electric vehicles (EV) generate much heat during rapid charge and discharge cycles at current levels exceeding the batteries’ rating, such as when the EV quickly starts consuming battery power or when recovering inertia energy during sudden stops. During these rapid charge and discharge cycles, the cell temperature may increase above allowable limits. We calculated the temperature rise of a small lithium-ion secondary battery during rapid charge and discharge cycles. The heat-source factors were measured again by the methods described in our previous study, because the performance of the battery reported here has been improved, showing lower overpotential resistance. Battery heat capacity was measured by a twin-type heat conduction calorimeter, and determined to be a linear function of temperature. Further, the heat transfer coefficient, measured again precisely by the method described in our previous study, was arranged as a function of cell and ambient temperatures. The temperature calculated by our battery thermal behavior model using these measured data agrees well with the cell temperature measured by thermocouple during rapid charge and discharge cycles. Also, battery radial temperature distributions were calculated to be small, and confirmed experimentally.

Introduction

Load leveling between power supply and demand by storing surplus power in nighttime for use during peak demand in daytime is promoted in order to narrow the gap between power demand in daytime and supply in nighttime [1]. Moreover, hybrid and electric vehicles (EV) are becoming more practical in order to alleviate the air pollution arising from the increasing number of automobiles [2]. Many institutions are conducting research and development on secondary lithium-ion batteries, as they have high energy and power densities combined with high charge and discharge efficiencies. Much anticipation therefore surrounds these batteries due to their potential use in power storage and electric vehicles. Rapid charging and discharging at higher current than the battery's rated current are anticipated for the large batteries that will be utilized in these applications. As battery size increases, however, the ratio of heat cooling area to heat generating volume decreases, and as charge/discharge current increases, more heat is generated. The temperature of battery thus rises dramatically, leading to the possibility that temperatures will exceed permissible levels. Additionally, charge/discharge characteristics improve as battery temperature increases. Thus, when temperature is distributed inside the battery, the local cell performance becomes uneven with an inclined current distribution in battery, which becomes a source of localized deterioration. Much has been reported about the materials and structures of batteries, but little has been reported on such thermal behavior of batteries as this paper.

We therefore set out to construct a model for analyzing thermal behavior of large lithium-ion secondary batteries during rapid charge and discharge cycles. First, in a previous study [3], we measured the heat-source terms of overpotential resistance and entropy change, however those measurements was conducted at only a discharge current below the battery's rated current. Using these measured data, battery temperatures were calculated by a thermal behavior model we constructed, being compared with measured battery temperatures. In that study, the measured and calculated temperatures were mostly in good agreement, and the reliability of our thermal behavior model was verified. For the present study, we attempted to expand the usable range of this model by testing whether or not it is also applicable to rapid charge and discharge cycles exceeding the battery's rated current. Using small lithium-ion secondary batteries with improved characteristics, we again measured the overpotential resistance, entropy change, and a more accurate heat transfer coefficient from the battery to the ambient air. The heat capacity of battery was also measured using a calorimeter. Using these measured data, the battery temperature during rapid charge and discharge cycles was calculated using the thermal behavior model. The numerical battery temperature was compared with the measured temperature of battery cooled under natural convection, showing that the calculated temperature mostly agreed with the measured, as explained below. Moreover, one-dimensional analysis of temperature in the radial direction of battery was performed, confirming that the radial temperature distribution in battery is nearly constant, which was also verified experimentally.

Section snippets

Charge/discharge reaction and heat-source terms in lithium-ion secondary battery

The cell tested here has a positive electrode of lithium cobalt oxide (LiCoO₂), a negative electrode of graphite carbon, and an electrolyte of lithium salt dissolved in organic solution. The charge/discharge reactions are written as follows [4]: $at positive electrode : LiCo O_{2} ⇄_{discharge}^{charge} □ Co O_{2} + L i^{+} + e^{-}$ $at negative electrode : □ C_{6} + L i^{+} + e^{-} ⇄_{discharge}^{charge} Li C_{6}$ $total cell reaction : LiCo O_{2} + □ C_{6} ⇄_{discharge}^{charge} □ Co O_{2} + Li C_{6}$ where □ represents the vacant site for lithium ions.

The charge and discharge

Measurement of heat-source factors

The battery tested here is a commercially-available, cylindrical lithium-ion battery (Sony-US18650G3 with 1800 mAh rated capacity, 18 mm diameter, and 65 mm length). In order to measure the heat-source factors of cell at a constant temperature similarly to the previous study, a cell was charged and discharged after being wrapped in a thin sheet for electrical insulation and immersed in a water thermostat. In this study as well, before each measurement was taken a cell was charged and discharged

Measurement of battery heat capacity

Unlike in the previous study, this time the heat capacity of battery was measured using a twin-type calorimeter (SETARAM C-80) [7], increasing the battery temperature from 20 to 90 °C at a constant rate of 0.4 °C min⁻¹. The measured data was compensated for the lag in thermal response by assuming a first-order time constant [8]. After determination of the heat capacity of battery from the compensated thermal response in the range where the heat up rate was constant, the heat capacity C_cell could

Inclusion of measured heat-source factors into analysis

In order to analyze thermal behavior of battery during charge and discharge cycles, the overpotential resistance to determine overpotential heat, the entropy change to determine entropy heat, the battery heat capacity, and the heat transfer coefficient from battery to ambient air were measured in the preceding sections. The overpotential resistance R_η was measured by four methods in Section 3.1. In the following analysis, the overpotential resistance R(V–I) determined from the battery V–I

Conclusion

Using small, commercially-available lithium-ion batteries, we have measured overpotential resistance, entropy change, battery heat capacity, and heat transfer coefficient to the ambient air from a battery attached with charge/discharge lead wires, which are needed to describe the battery thermal behavior. For overpotential resistance, the resistance by V–I characteristics during constant-current charge/discharge cycle, the resistance by difference between open-circuit voltage and cell voltage,

Acknowledgements

We would like to express our gratitude to Drs. Kiyonami Takano and Yoshiyasu Saito of the National Institute of Advanced Industrial Science and Technology for their advice on measurement of battery heat capacity. Part of this research was supported by the 21st Century COE Program “Intelligent Human Sensing” from the ministry of Education, Culture, Sports, Science and Technology.

References (9)

T. Ozawa et al.
Fuel cell and its application
(1981)
Electric Vehicle Handbook Editorial Committee, Electric Vehicle Handbook, Maruzen, Tokyo,...
K. Onda et al.
J. Electrochem. Soc
(2003)
Denchi-Binran Editorial Committee, Denchi-Binran, third ed., Maruzen, Tokyo,...

There are more references available in the full text version of this article.

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