CN113782829A - Sulfur-containing electrolyte and preparation method thereof - Google Patents
Sulfur-containing electrolyte and preparation method thereof Download PDFInfo
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- CN113782829A CN113782829A CN202110991794.2A CN202110991794A CN113782829A CN 113782829 A CN113782829 A CN 113782829A CN 202110991794 A CN202110991794 A CN 202110991794A CN 113782829 A CN113782829 A CN 113782829A
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- lithium
- sulfur
- containing electrolyte
- salt
- electrolyte
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- 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
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- 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
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- 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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- Physics & Mathematics (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- General Physics & Mathematics (AREA)
- Inorganic Chemistry (AREA)
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- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Secondary Cells (AREA)
Abstract
The invention discloses a sulfur-containing electrolyte and a preparation method thereof. Comprises a complex lithium salt and an additive; the complex lithium salt comprises lithium borate and lithium phosphate; such additives include thioalkyl nitriles and dihydrocarbyl sulfates. The sulfur-containing electrolyte can maintain better battery capacity stability under the condition of effectively inhibiting the problem of battery flatulence.
Description
Technical Field
The invention belongs to the technical field of electrolyte, and particularly relates to a sulfur-containing electrolyte and a preparation method thereof.
Background
The lithium ion battery has long service life and high capacity, and is widely popularized and used, but the problems of swelling, non-ideal safety performance and accelerated cycle attenuation are increasingly serious along with the prolonging of the service time, so that the analysis and inhibition research of the depth of a lithium battery interface is caused.
When the lithium ion battery is placed at normal temperature, high temperature and high temperature, the lithium ion battery can generate different degrees of gas generated by swelling, so that the thickness of the lithium ion battery is increased and the capacity of the lithium ion battery is reduced. According to the current research results, the essence of causing the cell flatulence is caused by the decomposition of the electrolyte.
Therefore, the development of a stable electrolyte without flatulence is urgent.
Disclosure of Invention
The first technical problem to be solved by the invention is as follows:
a sulfur-containing electrolyte is provided.
The second technical problem to be solved by the invention is:
a method for preparing a sulfur-containing electrolyte is provided.
In order to solve the first technical problem, the invention adopts the technical scheme that:
a sulfur-containing electrolyte comprising a complex lithium salt, an additive, and a solvent;
the complex lithium salt comprises lithium borate and lithium phosphate;
the additives include thioalkyl nitriles and dihydrocarbyl sulfates;
the weight portion ratio of the composite lithium salt to the additive is 20-25: 6-8.
According to an embodiment of the present invention, the lithium borate salt includes at least one of lithium difluorooxalato borate, lithium tetrafluoroborate, and lithium bisoxalato borate.
According to an embodiment of the present invention, the solvent includes at least one of ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate.
According to an embodiment of the present invention, the lithium phosphate salt includes at least one of lithium difluorophosphate, lithium tetrafluorophosphate, and lithium hexafluorophosphate.
According to one embodiment of the present invention, the above-mentioned thioalkyl nitrile includes 3,3' -dithiopropionitrile.
The addition of the thioalkyl nitrile can inhibit the gas generation of the battery under the high-voltage condition, so that the gas expansion condition of the battery under the high voltage is effectively solved; on the other hand, the thioalkyl nitrile can form an electrolyte interface film on the surface of the positive electrode, thereby preventing the co-intercalation of the solvent and reducing the occurrence of side reactions during the charge and discharge of the battery.
According to one embodiment of the present invention, the dialkyl sulfate includes ethylene sulfate and propylene sulfite.
The ethylene sulfate and the propylene sulfite can react with moisture in the electrode in the charging and discharging processes of the electrolyte, a thicker electrolyte interface film is formed on the negative electrode of the electrode, the film can inhibit the decomposition of the electrolyte under high pressure, and simultaneously, the problem of large volume expansion rate of the negative electrode of the electrode in the high-temperature holding process and the circulating process is solved. Based on this, the problem of battery ballooning caused by decomposition of moisture and electrolyte in the electrode is solved to some extent.
According to one embodiment of the present invention, the concentration of the lithium salt in the electrolyte is 4 to 7 mol/L.
By adjusting the concentration of the above lithium salt, formation of an electrolyte interface film on the electrode negative electrode by the thioalkyl nitrile, particularly 3,3' -dithiopropionitrile, can be more restricted. This is because the negative electrode of the lithium ion battery mainly uses a carbon-based negative electrode material mainly made of graphite, and the lithium intercalation potential of the negative electrode material is very close to the deposition potential of lithium, and although the working voltage and energy density of the lithium ion battery system are improved to some extent, due to the characteristics, the deposition of metal lithium on the surface of the carbon-based negative electrode material occurs under the high-rate charge and discharge conditions. If the thioalkyl nitrile forms an electrolyte interface film at the negative electrode, the free nitrile is promoted to react with the deposited lithium metal, which deteriorates the stability of the electrolyte solution and thus the cycle performance of the battery.
By utilizing the interfacial film of the ethylene sulfate and the propylene sulfite formed on the surface of the negative electrode and the interfacial film of the thioalkyl nitrile formed on the surface of the positive electrode, in particular to the interfacial film of the 3,3' -dithio propionitrile, the battery is more stable and safer, the problem of gas expansion is further reduced, and the cycle performance of the battery is also improved.
According to an embodiment of the present invention, the molar ratio of the lithium borate salt to the lithium phosphate salt in the complex lithium salt is 1-3: 1-3.
In order to solve the second technical problem, the invention adopts the technical scheme that:
a method for preparing the sulfur-containing electrolyte comprises the following steps:
and mixing the composite lithium salt, the additive and the solvent, and stirring at 60-80 ℃ for 25-45 minutes to obtain the anti-ballooning electrolyte.
According to an embodiment of the present invention, there is also provided a lithium battery including the sulfur-containing electrolyte.
One of the above technical solutions has at least one of the following advantages or beneficial effects:
1. on one hand, the thioalkyl nitrile added into the electrolyte can inhibit the electrolyte from generating gas under the condition of high voltage, so that the gas expansion condition of the battery under the high voltage is effectively solved; on the other hand, the above thioalkyl nitrile can form an electrolyte interface film on the surface of the positive electrode.
2. The ethylene sulfate and propylene sulfite added to the electrolyte can react with moisture in the electrode to form a thick electrolyte interface film on the negative electrode of the electrode.
3. The direct contact between the free nitrile and the metal lithium deposited from the electrode negative electrode can be limited by controlling the concentration of lithium ions in the electrolyte, so that the formation of an electrolyte interface film on the electrode negative electrode by the thioalkyl nitrile, particularly 3,3' -dithio propionitrile, can be limited.
4. Through the blending of the interfacial film, the battery is more stable, has better battery capacity retention rate, is safer and does not have the problem of gas expansion.
Detailed Description
In order to explain the technical content, the objects and the effects of the present invention in detail, the following description will be given with reference to the embodiments.
The weight ratio of the lithium salt to the additive is 20-25:6-8
The concentration of the lithium salt in the electrolyte is 4-7mol/L
The molar ratio of the lithium borate salt to the lithium phosphate salt in the composite lithium salt is 1-3:1-3
Example 1
10 parts by weight of lithium difluorooxalato borate, 10 parts by weight of lithium difluorophosphate, 2.5 parts by weight of ethylene sulfate, 2.5 parts by weight of propylene sulfite, 1 part by weight of 3,3' -dithiopropionitrile and 74 parts by weight of ethylene carbonate were mixed, and stirred at 60 ℃ for 30 minutes to obtain an anti-ballooning electrolyte.
Example 2
12.5 parts by weight of lithium difluorooxalato borate, 12.5 parts by weight of lithium difluorophosphate, 3 parts by weight of ethylene sulfate, 3 parts by weight of propylene sulfite, 2 parts by weight of 3,3' -dithiopropionitrile and 67 parts by weight of ethylene carbonate were mixed, and stirred at 60 ℃ for 30 minutes to obtain an anti-ballooning electrolyte.
Comparative example 1
10 parts by weight of lithium difluorooxalato borate, 10 parts by weight of lithium difluorophosphate, 2.5 parts by weight of ethylene sulfate, 2.5 parts by weight of propylene sulfite and 75 parts by weight of ethylene carbonate were mixed and stirred at 60 ℃ for 30 minutes to obtain an anti-ballooning electrolyte.
Comparative example 2
10 parts by weight of lithium difluorooxalato borate, 10 parts by weight of lithium difluorophosphate, 1 part by weight of 3,3' -dithiopropionitrile, and 79 parts by weight of ethylene carbonate were mixed, and stirred at 60 ℃ for 30 minutes to obtain an anti-gassing electrolyte.
And (3) performance testing:
the electrolytes of examples 1-2 and comparative examples 1-2 were used to prepare batteries, respectively, and then the performance of the batteries was tested, and the batteries were charged at 60 ℃ for 50 times per day in cycles, and after 7 days, the capacity retention rate and the thickness increase rate of the batteries were recorded.
| Capacity retention ratio/%) | Rate of increase in thickness/%) | |
| Example 1 | 91.2 | 1.6 |
| Example 2 | 88.3 | 2.1 |
| Comparative example 1 | 71.4 | 5.8 |
| Comparative example 2 | 54.3 | 6.9 |
Obviously, the battery prepared by the sulfur-containing electrolyte still maintains good capacity retention rate and thickness increase rate after long-time and multiple charging and discharging at high temperature, and the sulfur-containing electrolyte can maintain good battery capacity stability under the condition of effectively inhibiting the problem of battery gas expansion.
The above description is only an example of the present invention and is not intended to limit the scope of the present invention, and all equivalent modifications made by the present invention as described in the specification of the present invention or directly or indirectly applied to the related technical fields are included in the scope of the present invention.
Claims (9)
1. A sulfur-containing electrolyte, characterized by:
comprises a complex lithium salt, an additive and a solvent;
the complex lithium salt comprises lithium borate and lithium phosphate;
the additive comprises a thioalkyl nitrile and a dihydrocarbyl sulfate;
the weight portion ratio of the composite lithium salt to the additive is 20-25: 6-8.
2. The sulfur-containing electrolyte of claim 1, wherein:
the lithium borate salt comprises at least one of lithium difluorooxalate borate, lithium tetrafluoroborate and lithium bis (oxalate) borate.
3. The sulfur-containing electrolyte of claim 1, wherein:
the lithium phosphate salt comprises at least one of lithium difluorophosphate, lithium tetrafluorophosphate and lithium hexafluorophosphate.
4. The sulfur-containing electrolyte of claim 1, wherein:
the thioalkyl nitriles include 3,3' -dithiopropionitrile.
5. The sulfur-containing electrolyte of claim 1, wherein:
the dialkyl sulfate includes ethylene sulfate and propylene sulfite.
6. The sulfur-containing electrolyte of claim 1, wherein:
the concentration of the composite lithium salt in the electrolyte is 4-7 mol/L.
7. The sulfur-containing electrolyte of claim 1, wherein:
the molar ratio of the lithium borate salt to the lithium phosphate salt in the composite lithium salt is 1-3: 1-3.
8. A process for preparing a sulfur-containing electrolyte as claimed in any one of claims 1 to 7, wherein: the method comprises the following steps:
and mixing the composite lithium salt, the additive and the solvent, and stirring at 60-80 ℃ for 25-45 minutes to obtain the sulfur-containing electrolyte.
9. A lithium battery, characterized in that: comprising a sulfur-containing electrolyte as claimed in any one of claims 1 to 7.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
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| CN202110991794.2A CN113782829A (en) | 2021-08-27 | 2021-08-27 | Sulfur-containing electrolyte and preparation method thereof |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202110991794.2A CN113782829A (en) | 2021-08-27 | 2021-08-27 | Sulfur-containing electrolyte and preparation method thereof |
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| CN113782829A true CN113782829A (en) | 2021-12-10 |
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Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102201596A (en) * | 2006-12-06 | 2011-09-28 | 三菱化学株式会社 | Nonaqueous electrolyte solution and nonaqueous electrolyte secondary battery |
| CN102694207A (en) * | 2012-06-25 | 2012-09-26 | 奇瑞汽车股份有限公司 | Electrolyte for lithium ion batteries and lithium ion battery containing same |
| US20150140395A1 (en) * | 2013-11-20 | 2015-05-21 | Samsung Sdi Co., Ltd. | Electrolyte for rechargeable lithium battery and rechargeable lithium battery including same |
| CN108550912A (en) * | 2018-04-27 | 2018-09-18 | 天津市捷威动力工业有限公司 | A kind of electrolyte inhibiting lithium ion battery aerogenesis |
| CN109378524A (en) * | 2018-11-22 | 2019-02-22 | 福建冠城瑞闽新能源科技有限公司 | A kind of electrolyte for inhibiting lithium ion battery to produce gas |
| CN113013480A (en) * | 2021-02-20 | 2021-06-22 | 宁德新能源科技有限公司 | Electrochemical device and electronic device including the same |
-
2021
- 2021-08-27 CN CN202110991794.2A patent/CN113782829A/en active Pending
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102201596A (en) * | 2006-12-06 | 2011-09-28 | 三菱化学株式会社 | Nonaqueous electrolyte solution and nonaqueous electrolyte secondary battery |
| CN102694207A (en) * | 2012-06-25 | 2012-09-26 | 奇瑞汽车股份有限公司 | Electrolyte for lithium ion batteries and lithium ion battery containing same |
| US20150140395A1 (en) * | 2013-11-20 | 2015-05-21 | Samsung Sdi Co., Ltd. | Electrolyte for rechargeable lithium battery and rechargeable lithium battery including same |
| CN108550912A (en) * | 2018-04-27 | 2018-09-18 | 天津市捷威动力工业有限公司 | A kind of electrolyte inhibiting lithium ion battery aerogenesis |
| CN109378524A (en) * | 2018-11-22 | 2019-02-22 | 福建冠城瑞闽新能源科技有限公司 | A kind of electrolyte for inhibiting lithium ion battery to produce gas |
| CN113013480A (en) * | 2021-02-20 | 2021-06-22 | 宁德新能源科技有限公司 | Electrochemical device and electronic device including the same |
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