# US 8,541,119 B2 · Lithium secondary battery and method of controlling short resistance thereof

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- Number: US 8,541,119 B2
- Document ID: US8541119B2
- Status: Granted
- Kind: B2
- Application number: 12/910,636
- Filed: 2010-10-22
- Published: 2011-06-16
- Granted: 2013-09-24
- Earliest claimed: 2009-12-14
- Assignees: Samsung SDI Co., Ltd.
- Applicants: Joong-Heon Kim; Cheol-Ho Park; Jin-Uk Lee
- Inventors: Joong-Heon Kim; Cheol-Ho Park; Jin-Uk Lee
- Web page: https://patentgrep.com/patent/US8541119B2

## CPC

- H01M 10/056: characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
- H01M 10/0525: Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
- H01M 10/0565: Polymeric materials, e.g. gel-type or solid-type
- H01M 10/42: Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells (H01M10/60 takes precedence)
- Y02E 60/10: Energy storage using batteries
- Y02P 70/50: Manufacturing or production processes characterised by the final manufactured product
- 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
- Y02P: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS

## Abstract

Provided is a lithium secondary battery including a positive electrode having a positive electrode active material, a negative electrode having a negative electrode active material, and a polymer electrolyte composition having a polymer electrolyte, a non-aqueous organic solvent, and a lithium salt. The content of the polymer electrolyte is 9 to 20 wt %, based on the total weight of the polymer electrolyte composition.

## Claims

### Claim 1

A method of controlling a short resistance of a secondary battery, comprising:
measuring an open circuit voltage (VOC) of the secondary battery;
calculating a short circuit resistance (RSC) using the measured open circuit voltage (VOC);
calculating a heating value W according to time using the calculated short circuit resistance (RSC);
calculating a time having the maximum instantaneous heating value, using the change in heating value (W) according to time,
determining the short circuit resistance (RSC) value at the time having the maximum instantaneous heating value as a critical short resistance; and
adjusting an amount of a polymer electrolyte used in the secondary battery, according to the determined critical short resistance.

### Claim 2 (depends on 1)

The method according to claim 1, wherein the adjusting of the amount comprises adjusting the amount of the polymer electrolyte, such that the critical short resistance is not included in an RSC range having an ignition risk.

### Claim 3 (depends on 2)

The method according to claim 2, wherein the RSC range having an ignition risk occurs while the total heating value according to time is within 90% of the maximum level of the total heating value according to time.

### Claim 4 (depends on 1)

The method according to claim 1, wherein the heating value satisfies Equation 1:
W
=
(
V
oc
R
1
+
R
sc
+
R
)
2
*
R
sc
,
[
Equation
⁢
⁢
1
]
wherein VOC is an open circuit voltage, R1 is a specific resistance of the secondary battery, RSC is a short circuit resistance, and R is a specific resistance of a shorting pin.

### Claim 5 (depends on 4)

The method according to claim 4, wherein calculating of the heating value (W) according to time is performed by applying changes in the short circuit resistance (RSC) according to time to Equation 1.

### Claim 6 (depends on 1)

The method according to claim 1, wherein the short circuit resistance (RSC) satisfies Equation 2:
R
sc
=
V
sc
⁡
(
R
1
+
R
)
V
oc
-
V
sc
,
[
Equation
⁢
⁢
2
]
wherein VOC is an open circuit voltage, VSC is a short circuit voltage, R1 is a specific resistance of the secondary battery, and R is a specific resistance of a shorting pin.

### Claim 7 (depends on 6)

The method according to claim 6, wherein the calculating of the short circuit resistance (RSC) is performed by applying changes in the measured open circuit voltage to Equation 2.

### Claim 8 (depends on 1)

The method according to claim 1, wherein a positive electrode collector and a negative electrode active material layer are short-circuited in the secondary battery.