GB2328786A - Electrolyte for lithium ion battery and lithium ion battery employing the same - Google Patents
Electrolyte for lithium ion battery and lithium ion battery employing the same Download PDFInfo
- Publication number
- GB2328786A GB2328786A GB9818922A GB9818922A GB2328786A GB 2328786 A GB2328786 A GB 2328786A GB 9818922 A GB9818922 A GB 9818922A GB 9818922 A GB9818922 A GB 9818922A GB 2328786 A GB2328786 A GB 2328786A
- Authority
- GB
- United Kingdom
- Prior art keywords
- electrolyte
- ion battery
- solvent mixture
- lithium ion
- metal salt
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
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Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
- H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
- H01M10/0566—Liquid materials
- H01M10/0567—Liquid materials characterised by the additives
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
- H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
- H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
- H01M10/0566—Liquid materials
- H01M10/0568—Liquid materials characterised by the solutes
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
- H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
- H01M10/0566—Liquid materials
- H01M10/0569—Liquid materials characterised by the solvents
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- General Physics & Mathematics (AREA)
- Inorganic Chemistry (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- Physics & Mathematics (AREA)
- Materials Engineering (AREA)
- Secondary Cells (AREA)
- Battery Electrode And Active Subsutance (AREA)
- Carbon And Carbon Compounds (AREA)
Abstract
An electrolyte for a lithium ion battery containing an organic solvent mixture, lithium metal salt dissolved in the solvent and a surfactant of 0.01#5wt% based on the total weight of the organic solvent mixture and lithium metal salt, and a lithium ion battery employing the electrolyte. By using the electrolyte, a denser and more uniform solid electrolyte interface (SEI) film is formed on the surface of a negative electrode made of carbonic material, such that a side-reaction such as decomposition of the electrolyte is suppressed, thereby reducing irreversible capacity of the battery. Thus, cycle characteristics and life span of the lithium ion battery containing the electrolyte are improved.
Description
ELECTROLYTE FOR LITHIUM ION BATTERY AND LITHIUM ION BATTERY
EMPLOYING THE SAME
BACKGROUND OF THE INVENTION 1. Field of the Invention
The present invention relates to a lithium (Li) ion battery, and more particularly, to an electrolyte for a Li ion battery which is not easily discomposed by the reaction with a negative electrode active material and a Li ion battery employing the same.
2. Description of the Related Art
Recently, as portable electronic products such as camcoders, lap-top computers and cellular phones have become widespread, greater demands have been made on the performance of the batteries used as power sources of these devices.
Especially, much interest is focused on a Li ion battery as a battery capable of satisfying such demands.
A Li ion battery comprises a positive electrode and a negative electrode, each forming of materials capable of allowing intercalation and deintercalation of Li ions, and organic electrolyte or polymer electrolyte, in which Li ions can be movable, filled between the positive electrode and the negative electrode. Here, electrical energy is generated by oxidation and reduction reactions when the Li ions are intercalated/deintercalated in the positive electrode and negative electrode.
As the positive electrode of the Li ion battery, there is used a composite oxide of a transition metal and Li such as lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2) and lithium manganese oxide (LiMnO2), which has an electric potential higher than that of a Li/Li+ electrode by as much as about 3-4.5V, and allows intercalation/deintercalation of Li ions.
The negative electrode is formed of Li metal or its alloy capable of accepting or providing Li ions without changing its structure and electrical characteristics, or a carbonic material having similar chemical potential to that of Li metal during intercalation/deintercalation of Li ions. In particular, the carbonic material used as a negative electrode active material may be either a crystalline carbonic material or an amorphous carbonic material, according to its crystalline structure. For example, graphite is a crystalline carbonic material, and soft carbon obtained by thermally processing pitch at 1,0000C and hard carbon obtained by carbonizing polymer resin are amorphous carbonic materials.
The crystalline carbonic material has a good reversibility during the charging/discharging process.
However, its charging capacity is less. On the other hand, while the amorphous carbonic material has higher capacity than the crystalline carbonic material, it has a poor reversibility during the charging/discharging process. That is, in the case of the amorphous carbonic material, only 70-808 (irreversible capacity of 20-30%) of Li ions intercalated into a carbon lattice during the initial charging process are used in the next charging process. However, in the case of the crystalline carbonic material, the irreversible capacity is 10-15g.
The irreversible capacity is different according to the structure of carbonic material used as a negative electrode active material, the degree of reduction of electrolyte, and the structure of solid electrolyte interface film (SEI) formed at the surface of the negative electrode.
That is, if the SEI film formed at the surface of the negative electrode is not uniform, electrons of the negative electrode active material actively flow out via the film, to reduce the electrolyte, thereby decomposing the electrolyte.
If the electrolyte is decomposed, intercalation/deintercalation of Li into/from the carbon lattice is inhibited, thereby increasing the irreversible capacity of the negative electrode active material.
When the irreversible capacity increases as above, capacity and life span of the battery are reduced, and it is difficult to manufacture a battery capable of providing sufficiently high capacity at the minimum weight.
SUMMARY OF THE INVENTION
It is an objective of the present invention to provide an electrolyte for a lithium (Li) ion battery, which resists decomposition by forming a uniform and dense solid electrolyte interface (SEI) film on the surface of a negative electrode.
It is another objective of the present invention to provide a lithium ion battery whose life span is elongated, by reducing decomposition reaction of an electrolyte, caused by a carbonic material used as a negative electrode active material, to increase reversible capacity of the battery.
To achieve the first objective, there is provided an electrolyte for a lithium ion battery, comprising organic solvent mixture, lithium metal salt dissolved in the solvent mixture, andsurfactant of 0.01~5wt% based on the total weight of the organic solvent mixture and lithium metal salt.
To achieve the second objective, there is provided a lithium ion battery comprising: a positive electrode formed of a lithium composite oxide; a negative electrode formed of carbonic material; and an electrolyte containing an organic solvent mixture, lithium metal salt dissolved in the solvent mixture, and a surfactant of 0.01~5wt% based on the total weight of the organic solvent mixture and lithium metal salt.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
In the electrolyte for a lithium (Li) ion battery according to the present invention, the surfactant may be a urea or thiourea compound, or a non-ionic surfactant selected from the group consisting of polyethyleneglycoldimethylether and silicon polyparaphenyleneoxide (SiPPO).
Here, the content of the surfactant is 0.01-5wt based on the total weight of the organic solvent mixture and lithium metal salt, preferably, 0.05-3wt%. If the content of the surfactant is less than 0.01wtW, the effect of the surfactant is negligible and the SEI film loomed on the negative electrode active material is still not uniform. On the contrary, if the content of the surfactant is over 5wt%, the
SEI film is formed excessively thick, thereby lowering ion conductivity.
Also, preferably, the organic solvent mixture includes a solvent having a high dielectric constant and a solvent having a low-viscosity solvent to maintain a high electrical conductivity. For example, the solvent having a high dielectric constant may be ethylenecarbonate, propylenecarbonate or gamma butyrolactone, and the lowviscosity solvent may be dimethylcarbonate, diethylcarbonate or dimethoxyethane.
Also, the lithium metal salt which can be dissolved in such an organic solvent mixture may be LiPF6, LiAsF6, LiCF3SO3, LiN(CF3SO2) 3, LiBF6 or LiCl04, and a concentration of the lithium metal salt is preferably 0.5-1.5mol.
In the lithium ion battery according to the present invention, it is preferable to use an amorphous carbonic material, having less irreversible capacity, as the negative electrode active material. Such amorphous carbonic material may be a soft carbon obtained by thermal processing a precursor such as pitch at 1,0000C, or a hard carbon obtained by carbonizing a polymer resin. Here, the precursor of the soft carbon may be petroleum pitch, coal tar pitch or petroleum oil having a low molecular weight, and the precursor of the hard carbon may be polymer resin such as polyamide resin, furan resin, phenol resin, polyvinylalcohol resin, cellulose-resin, epoxy resin-or polystyrene resin.
The principle of the present invention is to add a surfactant to an electrolyte solution in order to improve a solid electrolyte interface (SEI) film which is formed by a side-reaction during charging. That is, the formed SEI film is uniform and dense enough to prevent the flow of electrons out from the negative electrode active material, and has a high ion conductivity with respect to Li ions, so the reduction of the electrolyte is reduced and the Li ions are reversibly accepted or emitted via the film. Accordingly, reversibility of the battery is increased, thereby improving cycle characteristics and life span of the battery.
Hereinafter, the present invention will be described in detail with reference to the following examples and comparative example. However, the present invention is not limited to the following examples.
Example 1 Lithium manganese oxide (LiMn2O4) for a positive electrode active material was dried at 1300C for 12 hours under a vacuum to completely remove water, and mixed with acetylene black and polytetrafluoroethylene dissolved in N-methylpyrrolidone to form a positive electrode active material. Then, the positive electrode active material was cast on aluminum foil to a thickness of 150cm, dried in an oven for 5 hours, and then compressed and molded to form a positive electrode.
Next, a coal tar from which impurities had been removed is cross-linked to synthesize a precursor, which is then heated 1,000 C to form a negative electrode active material in a powder form. The obtained powder is used to prepare a negative electrode.
Then, a non-aqueous organic electrolyte was prepared by adding 0.5g of thiourea to a Imol solution (bog) obtained by dissolving LiPF6 in a solvent mixture, in which ethylenecarbonate and dimethylcarbonate were mixed at a volume ratio of 2:1.
A Li ion battery was assembled using the above positive electrode, negative electrode and electrolyte, and its initial charging capacity, initial discharging capacity, battery efficiency and discharging capacity after 50 cycles were measured. The results are shown in Table 1.
Example 2
A positive electrode, negative electrode and electrolyte were prepared, and a Li ion battery was assembled, by the same method as in Example 1 except that lg of thiourea was added to form the electrolyte. The battery's initial charging capacity, initial discharging capacity, battery efficiency and discharging capacity after 50 cycles were measured, and the results are shown in Table 1.
Example 3
A Li ion battery was assembled by the same method as in
Example 1, except that the electrolyte was prepared by adding 0.3g of polyethyleneglycoldimethylether instead of thiourea.
The battery's initial charging capacity, initial discharging capacity, battery efficiency and discharging capacity after 50 cycles were measured, and the results are shown in Table 1.
Comparative Example
A Li ion battery was prepared by the same method as in
Example 1 except that thiourea was not used in preparing the electrolyte.
Table 1
Example 1 Example 2 Example 3 Comparative Example initial charging 432 441 435 437 capacity (mAh/g) initial discharging 316 340 361 306 capacity (mAh/g) S battery efficiency (%) 73 77 83 70 discharging capacity 278.1 906 337 244.8 after 50 cycles (mAh/g) As can be seen from the above result, the Li ion batteries according to the present invention (Examples 1, 2 and 3), obtained by using the electrolyte to which a small amount of surfactant is added, have higher efficiency than the
Li ion battery obtained by using the general electrolyte without surfactant (Comparative Example 1). Also, the Li ion battery according to the present invention has a high discharging capacity even after 50 cycles, so its life span is increased.
In the Li ion battery according to the present invention, the side-reaction such as decomposition of the electrolyte was suppressed by using the electrolyte containing surfactant. As a result, the problem of a high irreversible capacity, which is a defect of the Li ion battery employing the negative electrode made of carbonic material, particularly, amorphous carbonic material, can be improved, thereby also improving charging/discharging characteristics and life span of the battery.
Claims (12)
1. An electrolyte for a lithium ion battery, comprising an organic solvent mixture, lithium metal salt dissolved in the solvent mixture, and a surfactant of 0.01~5wit% based on the total weight of the organic solvent mixture and lithium metal salt.
2. The electrolyte according to claim 1, wherein the organic solvent mixture comprises a solvent having a high dielectric constant and a solvent having a low-viscosity.
3. The electrolyte according to claim 2, wherein the solvent having a high dielectric constant is selected from ethylenecarbonate, propylenecarbonate and gammabutyrolactone.
4. The electrolyte according to claim 2, wherein the solvent having a low-viscosity is selected from dimethylcarbonate, diethylcarbonate and dimethoxyethane.
5. The electrolyte according to any of claims 1 to 4, wherein the lithium metal salt is selected from LiPF6, LiAsF6, LiCF3SO3, LiN(CF3SO2)3, LiBF6 and Lilo4.
6. The electrolyte according to any of claims 1 to 5, wherein a concentration of the lithium metal salt is 0.5-1.5mol.
7. The electrolyte according to any of claims 1 to 6, wherein the surfactant is a urea or thiourea compound.
8. The electrolyte according to any of claims 1 to 6, wherein the surfactant is a non-ionic surfactant selected from polyethyleneglycoldimethylether and silicon polyparaphenyleneoxide (SiPPO).
9. The electrolyte according to any of claims 1 to 8, wherein the content of the surfactant is 0.05~3wit% based on the total weight of the organic solvent mixture and lithium metal salt.
10. A lithium ion battery comprising:
a positive electrode formed of a lithium composite oxide;
a negative electrode formed of carbonic material; and
an electrolyte containing an organic solvent mixture, lithium metal salt dissolved in the solvent mixture, and a surfactant of 0.01~5wt% based on the total weight of the organic solvent mixture and lithium metal salt.
11. The lithium ion battery of claim 10, wherein the carbonic material is an amorphous carbonic material.
12. The lithium ion battery of claim 10 or 11, wherein the electrolyte is as defined in any of claims 2 to 9.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| KR1019970044399A KR100263849B1 (en) | 1997-08-30 | 1997-08-30 | Lithium ion battery |
| KR1019980018309A KR100277786B1 (en) | 1998-05-21 | 1998-05-21 | Electrolyte for Lithium Secondary Battery |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB9818922D0 GB9818922D0 (en) | 1998-10-21 |
| GB2328786A true GB2328786A (en) | 1999-03-03 |
Family
ID=26633053
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB9818922A Withdrawn GB2328786A (en) | 1997-08-30 | 1998-08-28 | Electrolyte for lithium ion battery and lithium ion battery employing the same |
Country Status (2)
| Country | Link |
|---|---|
| JP (1) | JPH11126633A (en) |
| GB (1) | GB2328786A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7504181B2 (en) * | 2001-03-28 | 2009-03-17 | Kabushiki Kaisha Toshiba | Nonaqueous liquid electrolyte and nonaqueous liquid electrolyte secondary battery |
| US10079388B2 (en) | 2011-07-15 | 2018-09-18 | Solvay Specialty Polymers Italy S.P.A. | Aqueous vinylidene fluoride-(meth)acrylic co-polymer latex, electrode and lithium ion secondary battery using the same |
| CN115810797A (en) * | 2021-11-15 | 2023-03-17 | 宁德时代新能源科技股份有限公司 | Lithium ion battery, battery module, battery pack and electric device |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2001118578A (en) * | 1999-10-19 | 2001-04-27 | Ngk Insulators Ltd | Lithium secondary cell and method for manufacturing the same |
| US20030190530A1 (en) * | 2000-03-28 | 2003-10-09 | Li Yang | Lithium Secondary Battery |
| KR100813240B1 (en) * | 2005-02-18 | 2008-03-13 | 삼성에스디아이 주식회사 | Organic electrolytic solution and lithium battery employing the same |
| KR100803192B1 (en) | 2005-07-20 | 2008-02-14 | 삼성에스디아이 주식회사 | Organic electrolytic solution and lithium battery employing the same |
| CN101584075B (en) | 2006-12-22 | 2011-10-12 | 大金工业株式会社 | Nonaqueous electrolyte solution |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1444840A (en) * | 1974-03-28 | 1976-08-04 | Yardney International Corp | Current-producing organic electrolyte cells |
| JPH1092758A (en) * | 1996-09-11 | 1998-04-10 | Yamaha Corp | Wafer loading method |
| JP3285271B2 (en) * | 1994-02-21 | 2002-05-27 | 松下電工株式会社 | Water supply control device |
-
1998
- 1998-08-27 JP JP10242034A patent/JPH11126633A/en active Pending
- 1998-08-28 GB GB9818922A patent/GB2328786A/en not_active Withdrawn
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1444840A (en) * | 1974-03-28 | 1976-08-04 | Yardney International Corp | Current-producing organic electrolyte cells |
| JP3285271B2 (en) * | 1994-02-21 | 2002-05-27 | 松下電工株式会社 | Water supply control device |
| JPH1092758A (en) * | 1996-09-11 | 1998-04-10 | Yamaha Corp | Wafer loading method |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7504181B2 (en) * | 2001-03-28 | 2009-03-17 | Kabushiki Kaisha Toshiba | Nonaqueous liquid electrolyte and nonaqueous liquid electrolyte secondary battery |
| US10079388B2 (en) | 2011-07-15 | 2018-09-18 | Solvay Specialty Polymers Italy S.P.A. | Aqueous vinylidene fluoride-(meth)acrylic co-polymer latex, electrode and lithium ion secondary battery using the same |
| CN115810797A (en) * | 2021-11-15 | 2023-03-17 | 宁德时代新能源科技股份有限公司 | Lithium ion battery, battery module, battery pack and electric device |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH11126633A (en) | 1999-05-11 |
| GB9818922D0 (en) | 1998-10-21 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |