Additives for non-aqueous electrolyte and secondary battery using the same

• US 9,368,835 B2
• Filed: 05/16/2014
• Issued: 06/14/2016
• 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, Cho, Jeong-Ju, Lee, Hochun, Jeon, Joomi, Yu, Sunghoon
• Primary Examiner(s): Ryan, Patrick
• Assistant Examiner(s): Anthony, Julian
• Application Number:
  US14/279,705
• Publication Number:
  US 20140295221A1
• Time in Patent Office: 760 Days
• Field of Search: 429/327, 429/199, 429/326, 429/231.95, 429/162, 429/223, 429/224
• US Class Current: 1/1
• 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. A lithium secondary battery comprising:

a cathode, an anode, an electrolyte and a pressure sensing device or a temperature sensing device,

wherein the electrolyte comprises (a) an electrolyte salt;

(b) an electrolyte solvent comprising a combination of fluoroethylene carbonate, propylene carbonate and dimethyl carbonate; and

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

wherein the compound (c) is 1,4-dimethoxytetrafluorobenzene,

wherein the compound decomposes or evaporates electrolyte components by oxidation heat, thereby causing generation of gas, and

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.

2. The lithium secondary battery 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 lithium secondary battery of claim 1, wherein the compound (c) is a compound subjected to a reversible redox shuttle reaction.

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

5. The lithium secondary battery 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 lithium secondary battery of claim 1, wherein charge voltage is up to 4.35V.

7. The lithium secondary battery of claim 1, wherein a content of the compound (c) is within a range of 0.05 to 3 parts by weight, based on 100 parts by weight of the electrolyte.

8. The lithium secondary battery of claim 1, wherein a volume ratio of the fluoroethylene carbonate, the propylene carbonate and the dimethyl carbonate is 2:

1;

7.