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An Electrochemistry-Based Battery Impedance Model for Lithium-ion Batteries

Leonardo Ramos

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Outline Electrochemical Impedance Spectrum (EIS) Impedance Model of Lithium ion Batteries Schematic of a Li-ion Battery Internal Resistance (RS) Inductance (L) Double-layer Capacitance (Cdl) Charge-transfer Resistance (Rct) References

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Electrochemical Impedance Spectrum (EIS)

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Schematic of a Li-ion Battery

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Impedance Model of Lithium ion Batteries

Parameters: L: electrode inductance. RS: internal resistance. Cdl: double-layer capacitance. Rct: charge-transfer resistance.

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Internal Resistance (RS)

Type of Resistance Internal resistance of cell (RS = ionic resistance + electrical resistance + interfacial resistance)

Ionic • Electrode (cathode and anode) particle• Electrolyte

Electrical • Electrode (cathode and anode) particle• Conductive additives• Percolation network of additives in electrode • Current collectors• Electrical taps

Interfacial • Between electrolyte and electrodes• Between electrode particles and conductive additives• Between electrode and current collector• Between conductive additives and current collector

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Inductance (L) The impedance of the Li-ion battery at high frequency is

dominated by its inductive behavior. The inductance is attributed to:

the porosity of the electrodes; the electrode geometry; the conductive path formed by the terminals, connectors

and electrodes. The inductance parameter is geometrical and not

electrochemical.

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Double-layer Capacitance (Cdl) A charge zone is formed on the layer between the

electrode and electrolyte. Caused by the short distance and the large surface in

porous electrodes.

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Charge-transfer Resistance (Rct) Charge-transfer at the electrode interface in which

oxidation-reduction occurs:

Indicative of the kinetic rate of charge transfer reactions.

As, Cdl is on the electrode surface, it occurs in parallel to the electrochemical charge transfer reaction.

RCT//Cdl form a low-pass filter for the charge transfer reaction. Cdl can only carry alternative currents with a high frequency.

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References P. Moss, “Study of Capacity Fade of Lithium-Ion Polymer Battery With

Continuous Cycling & Power Performance Modeling of Energy Storage Devices,” PhD Thesis, The Florida State University, 2008.

Jossen A. “Fundamentals of battery dynamics,” Journal of Power Sources, 2006, 154:530–8.

Mantia, F. A., “Characterization of Electrodes for Lithium-Ion Batteries through Electrochemical Impedance Spectroscopy and Mass Spectrometry,” PhD Thesis, ETH ZURICH, 2008.

D. Linden, “Handbook of Batteries,” 3rd edition, McGraw-Hill, 2002. M. Park, et al., “A review of conduction phenomena in Li-ion batteries,”

Journal of Power Sources, 2010, v. 195, p. 7904-7929. L.H.J. Raijmakers, et al., “Sensorless battery temperature measurements

based on electrochemical impedance spectroscopy,” Journal of Power Sources, 2014, v. 247 , p. 539-544.