# US 5,700,298 A · Carbon anode for lithium ion electrochemical cell

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- Number: US 5,700,298 A
- Document ID: US5700298A
- Status: Granted
- Kind: A
- Application number: 08/616,826
- Filed: 1996-03-15
- Granted: 1997-12-23
- Earliest claimed: 1996-03-15
- Assignees: Valence Technology, Inc.
- Inventors: Hang Shi; Jeremy Barker; Rene Koksbang
- Web page: https://patentgrep.com/patent/US5700298A

## CPC

- H01M 10/0525: Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
- C01B 32/22: Intercalation
- H01M 4/587: for inserting or intercalating light metals
- H01M 4/1393: of electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
- H01M 2004/021: {Physical characteristics, e.g. porosity, surface area}
- Y02E 60/10: Energy storage using batteries
- Y10T 29/49108: Electric battery cell making
- H01M: PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- C01B: NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; {METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C}
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

Increasing the percentage of the 3R phase present in graphite reduces the first capacity loss of anodes employing the so modified graphite. Conversion of 2H phase graphite to 3R phase graphite can be achieved by grinding graphite. Non-aqueous solid electrochemical cells with improved performance can be fabricated by employing intercalation based carbon anodes comprising graphite with high percentage of 3R. When employed in an electrochemical cell, the first cycle capacity loss of only about 10%.

## Claims

### Claim 1

A method of preparing an electrochemical cell and controlling the first cycle capacity loss of said electrochemical cell, which method comprises the steps of:
(a) forming an intercalation based anode comprising graphite particles by a process comprising:
(i) providing an initial graphite composition;
(ii) measuring the percentage of 3R phase graphite present in said initial graphite composition;
(iii) increasing the percentage of 3R phase graphite in said initial graphite composition to form a second graphite composition which comprises graphite particles having an average diameter of less than 75 .mu.m;
(b) providing a cathode; and
(c) interposing a non-aqueous electrolyte containing a solvent and lithium salt between the anode and cathode.

### Claim 2 (depends on 1)

The method of claim 1 wherein the step of increasing the percentage of 3R phase graphite comprises:
converting graphite in the 2H phase to graphite in the 3R phase.

### Claim 3 (depends on 2)

The method of claim 2 wherein the step of converting the graphite forms graphite particles in said second graphite composition wherein the percentage of 3R phase graphite is at least about 30 percent.

### Claim 4 (depends on 1)

The method of claim 1 wherein the step of increasing the percentage of 3R phase graphite comprises:
grinding said initial graphite composition to convert graphite in the 2H phase to the 3R phase.

### Claim 5 (depends on 4)

The method of claim 4 wherein grinding said initial graphite composition produces particles having an average diameter in the range of about 5 to about 15 .mu.m.

### Claim 6 (depends on 1)

The method of claim 1 wherein the cathode comprises cathode active materials selected from lithiated cobalt oxides, lithiated manganese oxides, lithiated nickel oxides, lithiated vanadium oxides, and mixtures thereof.

### Claim 7

A method of preparing an electrochemical cell and reducing the first capacity loss of said electrochemical cell, which method comprises the steps of:
(a) forming an intercalation based anode comprising graphite particles by a process comprising:
(i) providing an initial graphite composition;
(ii) increasing the percentage of 3R phase graphite present in said initial graphite composition to form a second graphite composition which comprises graphite wherein at least 20 percent of the graphite is 3R phase graphite;
(b) providing a cathode; and
(c) interposing a non-aqueous electrolyte containing a solvent and lithium salt between the anode and cathode and wherein the electrochemical cell has a first cycle loss of less than about 15% and a specific capacity of greater than 300 mAh/g.

### Claim 8 (depends on 7)

The method of claim 7 wherein the step of increasing the percentage of 3R phase graphite forms graphite particles wherein the percentage of 3R phase graphite is at least about 30 percent.

### Claim 9 (depends on 7)

The method of claim 7 wherein the step of increasing the percentage of 3R phase graphite comprises:
grinding said initial graphite composition to convert graphite in the 2H phase to the 3R phase.

### Claim 10 (depends on 9)

The method of claim 9 wherein grinding said initial graphite composition produces graphite particles having an average diameter in the range of about 5 to about 15 .mu.m.

### Claim 11 (depends on 7)

The method of claim 7 wherein the cathode comprises cathode active materials selected from lithiated cobalt oxides, lithiated manganese oxides, lithiated nickel oxides, lithiated vanadium oxides, and mixtures thereof.

### Claim 12

A method of preparing an intercalation based carbon anode comprising graphite particles and controlling the first cycle capacity loss when employed in an electrochemical cell, which method comprises the steps of:
providing an initial graphite composition;
measuring the percentage of 3R phase graphite present in said initial graphite composition; and
increasing the percentage of 3R phase graphite in said initial graphite composition to form a second graphite composition which comprises graphite particles having an average diameter of less than 75 .mu.m wherein the second graphite composition has a lower first cycle capacity loss than the initial graphite composition when employed in the electrochemical cell.

### Claim 13 (depends on 12)

The method of claim 12 wherein the step of increasing the percentage of 3R phase graphite comprises:
converting graphite in the 2H phase to graphite in the 3R phase.

### Claim 14 (depends on 13)

The method of claim 13 wherein the step of converting the graphite forms graphite particles in said second graphite composition wherein the percentage of 3R phase graphite is at least about 30 percent.

### Claim 15 (depends on 12)

The method of claim 12 wherein the step of increasing the percentage of 3R phase graphite particles comprises:
grinding said graphite composition to convert graphite in the 2H phase to the 3R phase.

### Claim 16 (depends on 15)

The method of claim 15 wherein grinding said initial graphite composition produces graphite particles having an average diameter in the range of about 5 to about 15 .mu.m.

### Claim 17

A method of preparing an intercalation based carbon anode comprising graphite wherein the anode has less than about 10 percent first cycle capacity loss when employed in an electrochemical cell, which method comprises the steps of:
providing an initial graphite composition; and
increasing the percentage of 3R phase graphite in said initial graphite composition to form a second graphite composition which comprises graphite wherein at least about 20 percent of the graphite is 3R phase graphite wherein the second graphite composition has a lower first cycle capacity loss than the initial graphite composition when employed in the electrochemical cell.

### Claim 18 (depends on 17)

The method of claim 17 wherein the step of increasing the percentage of 3R phase graphite forms graphite particles wherein the percentage of 3R phase graphite in the graphite particles is at least about 30 percent.

### Claim 19 (depends on 17)

The method of claim 17 wherein the step of increasing the percentage of 3R phase graphite comprises:
grinding said initial graphite composition to convert graphite in the 2H phase to the 3R phase.

### Claim 20 (depends on 19)

The method of claim 19 wherein grinding said initial graphite composition produces graphite particles having an average diameter in the range of about 5 to about 15 .mu.m.