Impedance spectroscopy by voltage-step chronoamperometry using the Laplace transform method in a lithium-ion battery

Impedance spectroscopy by voltage-step chronoamperometry (VSCA) using the Laplace transform method is proposed. With this method an impedance Bode diagram for a very wide range of frequencies can be obtained by only one measurement of the current response to an applied voltage step change. Further, by applying staircase voltage-step chronoamperometry (SVSCA), each impedance diagram at each voltage step can be obtained, and it is easy to examine the change in the impedance of batteries due to discharging or charging. The VSCA method has been applied to a lithium-ion battery. II has been demonstrated that an impedance diagram for a wide range of frequencies between 1 mHz and several kilohertz can be obtained by only one VSCA and that the results obtained by this method agree with the results from applied sine-wave measurements in a battery at equilibrium. The impedance change at every 50 mV between 2.8 and 4.2 V due to discharging or charging is measured by applying SVSCA in a lithium-ion battery, and the results are discussed. The battery impedance is realized to increase due to discharging, and the impedance may be affected by the previous treatment applied to the battery. (C) 2000 The Electrochemical Society. S0013-4651(99)06-114-5. All rights reserved.