Novel State-of-Charge Estimation Method for Lithium Polymer Batteries Using Electrochemical Impedance Spectroscopy

Jong-Hak Lee; Woojin Choi

Novel State-of-Charge Estimation Method for Lithium Polymer Batteries Using Electrochemical Impedance Spectroscopy

Jong-Hak Lee

Woojin Choi

Vol. 11, No. 2, pp. 237-243, Mar. 2011

10.6113/JPE.2011.11.2.237

Electrochemical impedance spectroscopy

Lithium Polymer Battery

Randle’s Circuit

State-of-charge

Time Constant

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Abstract

Lithium batteries are widely used in mobile electronic devices due to their higher voltage and energy density, lighter weight and longer life cycle when compared to other secondary batteries. In particular, a high demand for lithium batteries is expected for electric cars. In the case of the lithium batteries used in electric cars, driving distance must be calculated accurately and discharging should not be done below a level that makes it impossible to crank. Therefore, accurate information on the state-ofcharge (SOC) becomes an essential element for reliable driving. In this paper, a novel method for estimating the SOC of lithium polymer batteries using AC impedance is proposed. In the proposed method, the parameters are extracted by fitting the measured impedance spectrum on an equivalent impedance model and the variation in the parameter values at each SOC is used to estimate the SOC. Also to shorten the long length of time required for the measurement of the impedance spectrum, a novel method is proposed that can extract the equivalent impedance model parameters of lithium polymer batteries with the impedance measured at only two specific frequencies. Experiments are conducted on lithium polymer batteries, with similar capacities, made by different manufacturers to prove the validity of the proposed method.

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Cite this article

[IEEE Style]

J. Lee and W. Choi, "Novel State-of-Charge Estimation Method for Lithium Polymer Batteries Using Electrochemical Impedance Spectroscopy," Journal of Power Electronics, vol. 11, no. 2, pp. 237-243, 2011. DOI: 10.6113/JPE.2011.11.2.237.

[ACM Style]

Jong-Hak Lee and Woojin Choi. 2011. Novel State-of-Charge Estimation Method for Lithium Polymer Batteries Using Electrochemical Impedance Spectroscopy. Journal of Power Electronics, 11, 2, (2011), 237-243. DOI: 10.6113/JPE.2011.11.2.237.