ADDITIVES FOR NON-AQUEOUS ELECTROLYTE AND SECONDARY BATTERY USING THE SAME

• US 20100297481A1
• Filed: 05/15/2008
• Published: 11/25/2010
• Est. Priority Date: 05/15/2007
• Status: Active Grant

• Current Assignee: LG Energy Solution Limited (LG Corporation)
• Original Assignee: LG Chem Limited (LG Corporation)
• Inventors: Son, Miyoung, Jeon, Joomi, Cho, Jeong-Ju, Lee, Hochun, Yu, Sunghoon
• Granted Patent: US 8,785,015 B2
• Time in Patent Office: Days
• US Class Current: 429/56
• CPC Class Codes: H01M 10/052 Li-accumulators
• CPC Class Codes: H01M 10/0567 characterised by the additives
• CPC Class Codes: H01M 10/4235 Safety or regulating additives or arrangements in electrodes, separators or electrolyte H01M10/4242 takes precedence
• CPC Class Codes: H01M 10/44 Methods for charging or discharging circuits for charging H02J7/00
• CPC Class Codes: 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
• CPC Class Codes: H01M 10/486 for measuring temperature
• CPC Class Codes: H01M 50/30 Arrangements for facilitating escape of gases
• CPC Class Codes: Y02E 60/10 Energy storage using batteries
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries

Abstract

Disclosed are an electrolyte for a secondary battery, and a secondary battery including the same, the electrolyte including an electrolyte salt; an electrolyte solvent; and a compound generating heat through oxidation at voltages higher than drive voltage of a cathode, wherein the compound can decompose or evaporate electrolyte components by oxidation heat, thereby causing gas generation. Also, the compound is included in an internal pressure increase accelerant for a battery. Upon overcharge, since a compound subjected to oxidation at voltages higher than normal drive voltage of a cathode generates heat, electrolyte components can be decomposed or evaporated, thereby generating gas by the oxidation heat. Accordingly, it is possible to operate a safety means of a battery, without using an internal pressure increasing material directly generating gas through oxidation at overcharge voltage as the electrolyte additive, and thus to improve the overcharge safety of a secondary battery.

Claims

1. An electrolyte for a secondary battery comprising:

(a) an electrolyte salt;

(b) an electrolyte solvent; and

(c) a compound generating heat through oxidation at voltages higher than drive voltage of a cathode,

wherein the compound can decompose or evaporate electrolyte components by oxidation heat, thereby causing generation of gas.

2. The electrolyte of claim 1, wherein an amount of the heat generated by the oxidation of the compound (c) is equal to or more than a range where the electrolyte components are decomposed or evaporated, and is less than a range where structural breakdown of a cathode active material is caused.

3. The electrolyte of claim 1, wherein the compound (c) is a compound subjected to a reversible redox shuttle reaction.

4. The electrolyte of claim 3, wherein the compound subjected to the reversible redox shuttle reaction generates heat at both oxidation and reduction.

5. The electrolyte of claim 1, wherein an amount of the gas generated by the compound (c) is within a range where a safety means sensing pressure change within the battery can operate.

6. The electrolyte of claim 1, wherein the compound (c) is selected from the group including 1,4-dimethoxytetrafluorobenzene, and 5,6,7,8-tetrafluorobenzo-1,4-dioxane.

7. The electrolyte of claim 1, wherein a content of the compound (c) is within a range of 0.05 to 5 parts by weight, based on 100 parts by weight of the electrolyte.

8. A secondary battery comprising a cathode;

an anode; and

the electrolyte of claim 1.

9. The secondary battery of claim 8, wherein charge voltage is up to 4.35V.

10. The secondary battery of claim 8 further comprising at least one selected from the group including (a) a first safety means for discontinuing battery charge or converting a charge state into a discharge state, and (b) a second safety means for emitting heat or gas within the battery to outside, after sensing a change in pressure and/or temperature within the battery.

11. The secondary battery of claim 10, wherein the first safety means comprises a pressure sensing device, and/or a temperature sensing device.

12. The secondary battery in of claim 10, wherein the first safety means comprises:

a pressure sensing device;

or

(i) a pressure sensing member;

(ii) a conducting wire for transferring current transferred from the pressure sensing member; and

(iii) a member for discontinuing device charge or converting the charge state into the discharge state, in response to the current transferred through the conducting wire.

13. The secondary battery of claim 10, wherein the first safety means comprises:

a temperature sensing device;

or

(i) a temperature sensing member;

(ii) a conducting wire for transferring current transferred from the temperature sensing member; and

(iii) a member for discontinuing device charge or converting the charge state into the discharge state, in response to the current transferred through the conducting wire.

14. The secondary battery of claim 10, wherein the second safety means comprises a pressure relief valve.

15. The secondary battery of claim 10, wherein the first safety means and/or the second safety means are/is operated by temperature increase within the battery by oxidation heat generated from a compound oxidized at voltages higher than drive voltage of the cathode, and/or by volume expansion of the battery and pressure increase within the battery by gas blow-off pressure of electrolyte components.

16. The secondary battery of claim 8, which is a lithium secondary battery.

17. An internal pressure increase accelerant for a battery comprising a compound subjected to oxidation at voltages higher than drive voltage of a cathode, wherein an amount of heat generated by the oxidation is within a range where electrolyte components can be decomposed or evaporated, thereby generating gas.

18. The internal pressure increase accelerant of claim 17, wherein the compound is selected from the group including 1,4-dimethoxytetrafluorobenzene and 5,6,7,8-tetrafluorobenzo-1,4-dioxane.