ELECTROCHEMICAL ANALYSIS APPARATUS AND ELECTROCHEMICAL SYSTEM

• US 20150276889A1
• Filed: 03/27/2015
• Published: 10/01/2015
• Est. Priority Date: 03/28/2014
• Status: Abandoned Application

• Current Assignee: Waseda University (Waseda University Educational Association)
• Original Assignee: Waseda University (Waseda University Educational Association)
• Inventors: OSAKA, Tetsuya, MOMMA, Toshiyuki, YOKOSHIMA, Tokihiko, MUKOYAMA, Daikichi, NARA, Hiroki
• Application Number:
  US14/671,200
• Publication Number:
  US 20150276889A1
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G01R 31/367 Software therefor, e.g. for battery testing using modelling or look-up tables
• CPC Class Codes: G01R 31/389 Measuring internal impedance, internal conductance or related variables

Abstract

An electrochemical analysis apparatus includes a power controller, a Fourier transform unit, and a calculating unit. The power controller generates a rectangular-wave signal, a first frequency F and a duty ratio D, and applies the signal to an electrochemical cell. The Fourier transform unit performs Fourier transform on first data obtained by sampling a response signal of the cell to calculate a first frequency characteristic including a component of a second frequency integer times as high as the first frequency. The Fourier transform unit performs Fourier transform on second data, a sampling start time of which is (1/F)·D (seconds) different from the first data from which the first frequency characteristic is calculated, to calculate a second frequency characteristic including a component of the second frequency. The calculating unit calculates an impedance characteristic of the cell based on the first frequency characteristic and the second frequency characteristic.

Claims

1. An electrochemical analysis apparatus comprising:

a power controller that generates a rectangular wave signal, a frequency of which is a first frequency F and a duty ratio (TON/(TON+TOFF)) of which is D, and applies the rectangular wave signal to an electrochemical cell including a plurality of electrodes and an electrolyte;

a Fourier transform unit that subjects first data obtained by sampling a response signal of the electrochemical cell to the rectangular wave signal for (1/F) second to Fourier transform and calculates a first frequency characteristic including a component of a second frequency, which is integer times as high as the first frequency, and subjects second data, a sampling start time of which is (1/F)×

D (seconds) different from the data from which the first frequency characteristic is calculated, to the Fourier transform and calculates a second frequency characteristic including a component of the second frequency integer times as high as the first frequency; and

a calculating unit that calculates an impedance characteristic of the electrochemical cell based on the first frequency characteristic and the second frequency characteristic.

2. The electrochemical analysis apparatus according to claim 1, wherein

the duty ratio:

D is 1/2, and

the sampling start time is (1/F)×

(1/2) (seconds) different.

3. The electrochemical analysis apparatus according to claim 1, wherein the second frequency is a frequency odd number times as high as the first frequency.

4. The electrochemical analysis apparatus according to claim 3, wherein the first frequency is 1 Hz or less.

5. The electrochemical analysis apparatus according to claim 4, wherein

the power controller applies, to the electrochemical cell, a signal that is formed by rectangular wave signals having the first frequency in plurality and has a third frequency lower than the first frequency, and

the Fourier transform unit calculates a frequency characteristic including a component of the third frequency.

6. The electrochemical analysis apparatus according to claim 4, wherein

the power controller applies rectangular wave signals having a plurality of frequencies to the electrochemical cell, and

the Fourier transform unit calculates a frequency characteristic of a component of a frequency integer times as high as each of the plurality of frequencies.

7. The electrochemical analysis apparatus according to claim 6, wherein the plurality of frequencies of the rectangular wave signals are set such that frequencies odd number times as high as the frequencies are different.

8. The electrochemical analysis apparatus according to claim 1, wherein the electrochemical cell is a power storage device.

9. The electrochemical analysis apparatus according to claim 8, wherein the calculating unit further detects a characteristic change of the power storage device from the impedance characteristic.

10. The electrochemical analysis apparatus according to claim 9, wherein

the power controller applies the rectangular wave signal to a power storage unit including a plurality of power storage devices connected to one another, and

the calculating unit detects a characteristic change of the power storage unit.

11. The electrochemical analysis apparatus according to claim 9, wherein the power storage device is a secondary battery.

12. The electrochemical analysis apparatus according to claim 11, wherein internal resistance of the secondary battery is 10 mΩ

or less.

13. The electrochemical analysis apparatus according to claim 1, wherein the rectangular wave signal generated by the power controller is a direct current.

14. An electrochemical system comprising:

the electrochemical analysis apparatus according to claim 1; and

the electrochemical cell.