Nondestructive method for measuring active area of active material

Patent metadata

Field	Value
Publication number	US-11313822-B2
Application number	US-201917055807-A
Country	US
Kind code	B2
Filing date	Nov 27, 2019
Priority date	Dec 3, 2018
Publication date	Apr 26, 2022
Grant date	Apr 26, 2022

Abstract

The present invention relates to a method for measuring the active area of an active material in an electrode, comprising: manufacturing three types of electrodes including a first electrode coated with an electrode mixture including both an electrode active material and a conductive material, a second electrode coated with an electrode mixture which includes the electrode active material as a main ingredient and does not include the conductive material, and a third electrode coated with an electrode mixture which does not include the active material and includes the conductive material as a main ingredient; a cell manufacturing step of manufacturing three types of monocells by using the same types of electrodes; a capacitance measuring step of measuring, from the monocells, capacitance of each electrode used in the monocells; and an active area calculating step of calculating the active area of the electrode active material from the capacitance.

First claim

The invention claimed is:

1. A method for measuring an active area of a non-destructive active material, the method comprising:
manufacturing three electrodes comprising a first electrode coated with an electrode mixture containing an electrode active material and a conductive material, a second electrode coated with an electrode mixture containing the electrode active material as its main component and not containing the conductive material, and a third electrode coated with an electrode mixture containing no electrode active material and containing the conductive material as its main component;
manufacturing three monocells using the first, second and third electrodes;
measuring a capacitance of each of the first, second and third electrodes used in the monocells; and
calculating an active area (m 2 ) of the electrode active material by a following Formula 1,
A A.M =( C total −C CNT *A CNT )/ C A.M   [Formula 1]

in Formula 1,
A A.M denotes the active area (m 2 ) of the electrode active material coated on the first electrode,
A CNT denotes a surface area (m 2 ) of the conductive material coated on the first electrode,
C total denotes a capacitance (F) of the first electrode,
C CNT denotes a capacitance per unit surface area of the conductive material (F/m 2 ), and
C A.M denotes the capacitance per unit surface area of the electrode active material (F/m 2 ).

2. The method of claim 1 , wherein the surface area of the conductive material or the electrode active material is measured by Brunauer-Emmett-Teller (BET).

3. The method of claim 1 , wherein the monocells comprise two-electrode symmetric cells using the first, second and third electrodes.

4. The method of claim 1 , wherein the conductive material comprises a carbon nanotube (CNT).

5. The method of claim 1 , wherein the electrode active material comprises a positive electrode active material, and an electrode including the positive electrode active material is a positive electrode.

6. The method of claim 1 , wherein the electrode active material comprises a lithium nickel cobalt manganese composite oxide.

7. The method of claim 1 , wherein the measuring the capacitance includes measuring the capacitance of the electrode by cyclic voltammetry for the monocells.

8. The method of claim 7 , wherein the measuring of the capacitance comprises:
applying a voltage to the monocells at a constant scan rate;
measuring a response current according to the applied voltage; and
showing a cyclic voltammogram from a relationship between the scan rate of the applied voltage and the response current and calculating capacitance therefrom.

9. The method of claim 8 , wherein the capacitance is calculated by using a linear regression method of obtaining a slope by plotting response currents according to the voltage scan rate in a straight line.

10. The method of claim 8 , wherein the response current is measured at a point where an x-axis value is 0 V in the cyclic voltammogram when measuring the current.

11. The method of claim 1 , wherein the first electrode further includes a binder and a dispersant, and a weight ratio of the electrode active material, the conductive material, the binder, and the dispersant is 95:3:1.5:0.5 to 98:0.5:1:0.5 in the first electrode.

12. The method of claim 1 , wherein the second electrode contains 99.5 to 99.8% by weight of the electrode active material.

13. The method of claim 1 , wherein the electrode mixture of the third electrode comprises a pre-dispersion liquid containing a conductive material as its main component.

Assignees

• Lg Chemical Ltd
• Lg Energy Solution Ltd

Inventors

• Park Ji Hye
• Kim Seok Koo

Classifications

• Y02P70/50

  Manufacturing or production processes characterised by the final manufactured product · CPC title

• H01M10/052

  Li-accumulators · CPC title

• G01N15/088 Primary

  Investigating volume, surface area, size or distribution of pores; Porosimetry · CPC title

• Y02E60/10

  Energy storage using batteries · CPC title

• G01N27/48

  using polarography, i.e. measuring changes in current under a slowly-varying voltage · CPC title