# US 12,222,401 B2 · Method of diagnosing degradation of electrode active material for lithium secondary battery

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- Number: US 12,222,401 B2
- Document ID: US12222401B2
- Status: Granted
- Kind: B2
- Application number: 17/774,666
- Filed: 2021-01-12
- Published: 2022-12-15
- Granted: 2025-02-11
- Earliest claimed: 2020-01-20
- Assignees: LG Energy Solution, Ltd.
- Applicants: LG Energy Solution, Ltd.
- Inventors: Su Won Jee; Hyo Jung Yoon; Young Deok Kim; Ji Yeon Kim; Dae Soo Kim
- Web page: https://patentgrep.com/patent/US12222401B2

## CPC

- G01R 31/392: Determining battery ageing or deterioration, e.g. state of health
- G01R 31/3646: {for indicating electrical conditions or variables, e.g. visual or audible indicators}
- G01R 31/3865: {related to manufacture, e.g. testing after manufacture}
- H01M 4/386: {Silicon or alloys based on silicon}
- H01M 4/485: of mixed oxides or hydroxides for inserting or intercalating light metals, e.g. LiTi2O4 or LiTi2OxFy (H01M4/505, H01M4/525 take precedence)
- H01M 4/505: of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy
- H01M 4/525: of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
- H01M 10/052: Li-accumulators
- H01M 10/0525: Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
- H01M 10/058: Construction or manufacture
- H01M 10/42: Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells (H01M10/60 takes precedence)
- H01M 10/4285: {Testing apparatus}
- H01M 10/44: Methods for charging or discharging (circuits for charging H02J7/00)
- H01M 10/446: {Initial charging measures}
- H01M 10/48: Accumulators combined with arrangements for measuring, testing or indicating the condition of cells, e.g. the level or density of the electrolyte (constructional details of current conducting connections for detecting conditions inside cells or batteries, e.g. details of voltage sensing terminals, H01M50/569)
- G01R 31/378: specially adapted for the type of battery or accumulator
- H01M 2004/027: {Negative electrodes}
- H01M 2004/028: {Positive electrodes}
- Y02E 60/10: Energy storage using batteries
- G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12)
- H01M: PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION

## Abstract

A method of diagnosing degradation of an electrode active material for a secondary battery including obtaining a first differential curve (dQ/dV) by differentiating an initial charge/discharge curve obtained by performing first charging and first discharging of the lithium secondary battery in a voltage range of 2.5 V to 4.2 V, and obtaining a second differential curve (dQ/dV) by differentiating a charge/discharge curve obtained by performing second charging and second discharging of the lithium secondary battery in a voltage range of 2.5 V to 4.2 V, and diagnosing whether a beta phase of the positive electrode active material has been formed by comparing maximum discharge peak values of the first differential curve and the second differential curve.

## Claims

### Claim 1

A method of diagnosing degradation by beta phase formation of an electrode active material for a secondary battery, comprising:
preparing a lithium secondary battery which includes a positive electrode including a positive electrode active material of a lithium transition metal oxide containing nickel (Ni) in an amount of 60 mol % or more based on a total number of moles of transition metals except lithium, and a negative electrode facing the positive electrode;
performing first charging and first discharging of the lithium secondary battery in a voltage range of 2.5 V to 4.2 V, measuring an initial charge/discharge curve of the lithium secondary battery, and then differentiating the initial charge/discharge curve to obtain a first differential curve (dQ/dV) of the lithium secondary battery;
performing second charging and second discharging of the lithium secondary battery in a voltage range of 2.5 V to 4.2 V, measuring a second charge/discharge curve of the lithium secondary battery, and then differentiating the second charge/discharge curve to obtain a second differential curve (dQ/dV) of the lithium secondary battery, and
diagnosing that a beta phase of the positive electrode active material has been formed by determining when spaced-apart peaks are observed at 4.0 V or more with a maximum discharge peak value of the second differential curve at 4.0 V or more compared to a maximum discharge peak value of at 4.0 V or more of the first differential curve is spaced apart within a range of 0.01 V to 0.1 V.

### Claim 2 (depends on 1)

The method of claim 1, wherein the second charging and the second discharging are charging and discharging after charging and discharging of the secondary battery subjected to the first charging and the first discharging are repeated 1 to 10 times.

### Claim 3 (depends on 2)

The method of claim 2, wherein reversible capacity of lithium is reduced by the repeated charging and discharging of the secondary battery subjected to the first charging and the first discharging or after a storage of the secondary battery subjected to the first charging and the first discharging.

### Claim 4 (depends on 3)

The method of claim 3, wherein an operating voltage of the negative electrode is changed by a reduction in reversible capacity of the lithium.

### Claim 5 (depends on 4)

The method of claim 4, wherein the operating voltage of the negative electrode is increased by the reduction in the reversible capacity of the lithium.

### Claim 6 (depends on 4)

The method of claim 4, wherein the operating voltage of the negative electrode is changed by the reduction in the reversible capacity of the lithium to increase a potential of the positive electrode.

### Claim 7 (depends on 6)

The method of claim 6, wherein a structure of the positive electrode active material is changed by the increase in the potential of the positive electrode.

### Claim 8 (depends on 1)

The method of claim 1, wherein the second charging and the second discharging are charging and discharging after storing the secondary battery subjected to the first charging and the first discharging at 60° C. for 2 weeks to 10 weeks.

### Claim 9 (depends on 8)

The method of claim 8, wherein reversible capacity of lithium is reduced by a repeated charging and discharging of the secondary battery subjected to the first charging and the first discharging or the storage of the secondary battery subjected to the first charging and the first discharging.

### Claim 10 (depends on 1)

The method of claim 1, wherein the positive electrode active material is represented by Formula 1:
Li1+aNi1-x-yCoxM1yO2 [Formula 1]
wherein, in Formula 1,
0≤a≤0.3, 0≤x≤0.2, 0≤y≤0.2, and 0≤x+y≤0.4, and
M1 is at least one selected from manganese (Mn) and aluminum (Al).

### Claim 11 (depends on 1)

The method of claim 1, wherein the negative electrode comprises a silicon-based negative electrode active material.

### Claim 12 (depends on 1)

The method of claim 1, wherein the amount of nickel (Ni) contained in the lithium transition metal oxide is from 80 mol % or more based on a total number of moles of transition metals except lithium.