CN114142091A - Non-aqueous electrolyte of lithium ion battery and lithium ion battery - Google Patents
Non-aqueous electrolyte of lithium ion battery and lithium ion battery Download PDFInfo
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- CN114142091A CN114142091A CN202111406054.4A CN202111406054A CN114142091A CN 114142091 A CN114142091 A CN 114142091A CN 202111406054 A CN202111406054 A CN 202111406054A CN 114142091 A CN114142091 A CN 114142091A
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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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- 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
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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
- H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
- H01M10/4235—Safety or regulating additives or arrangements in electrodes, separators or 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
- H01M2300/00—Electrolytes
- H01M2300/0088—Composites
- H01M2300/0091—Composites in the form of mixtures
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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
Abstract
The invention provides a lithium ion battery non-aqueous electrolyte and a lithium ion battery. The lithium ion battery non-aqueous electrolyte comprises a composite lithium salt, a non-aqueous solvent and an additive, wherein the additive comprises a lithium salt additive, a silane additive and a sulfite additive, and the composite lithium salt comprises lithium bis (fluorosulfonyl) imide and an auxiliary salt. According to the invention, by regulating and controlling the electrolyte formula, the lithium salt additive and the silane additive are subjected to synergistic action, the problem that the high-content lithium bis (fluorosulfonyl) imide corrodes an aluminum foil in the battery cycle process is solved, and a stable SEI film can be formed on the surface of a positive electrode material. In order to further reduce film forming impedance and change an SEI film structure, the invention introduces the sulfite additive, so that the ternary cathode material system meets the performance requirements of low-temperature power, high-temperature circulation, high-temperature storage and the like.
Description
Technical Field
The invention belongs to the field of batteries, and particularly relates to a lithium ion battery non-aqueous electrolyte and a lithium ion battery.
Background
The electric automobile has the characteristics of economy and oil saving, but still has a plurality of defects, mainly including aspects such as high power, long service life and safe and reliable. In order to further increase the charge/discharge rate of a lithium ion battery, it is necessary to increase the mobility rate of lithium ions and increase the mobility rate of electrons. The methods adopted by researchers include: (1) thinning an electrode: the compaction density is reduced by using a carbon-coated foil material, and a strong conductive agent (such as novel carbon nano tubes, graphene and the like) is added into an electrode material formula to establish a three-dimensional conductive network; (2) nanocrystallization and surface coating: the anode and cathode materials with smaller particles are selected, and the surface of the anode and cathode materials is coated with the conducting layer so as to reduce impedance, and meanwhile, the electrolyte with high conductivity and lithium ion migration number is utilized, so that the lithium ion migration dynamics is improved.
Compared with the lithium ion battery, the high-power lithium ion battery has higher requirements on the indexes and comprehensive performances of high and low temperature performance, power performance and cycle life. When the lithium ion battery is charged and discharged under high current density, the lithium ion battery not only has rapid lithium ion migration capacity between the positive electrode and the negative electrode when needing to be discharged; it is also necessary that lithium does not precipitate on the negative electrode side during charging. The electrolyte is used as an important component of the lithium ion battery, plays roles in transmitting lithium ions in a liquid phase and promoting the surface film formation of positive and negative electrode materials, and the composition of the electrolyte is one of main factors influencing the performance of the high-power lithium ion battery. Therefore, it is required to develop an electrolyte that can satisfy the requirements of high power charge and discharge and high and low temperature performance.
In the prior art, the problem of battery performance deterioration is mainly solved by adding high-conductivity lithium salt, a low-viscosity solvent and a low-impedance additive, but the problem still exists that aluminum foil is corroded to influence the subsequent cycle performance of the battery. CN111640977A discloses a 3-methoxy ethyl propionate solvent, which improves the conductivity of electrolyte and the migration rate of lithium ions, but has the problems of insufficient high-temperature performance and higher cost, and is difficult to be practically applied. CN100470915A discloses a nonaqueous electrolyte for lithium ion batteries, however, the cycle life and specific capacity of lithium ion batteries still need to be further improved.
Based on the above considerations, it is desirable to develop an electrolyte system that can be applied to lithium salts with high conductivity and high thermal stability, and simultaneously solve the problem of corrosion of the lithium salts to aluminum foil, thereby improving the low-temperature power, high-temperature cycle and high-temperature storage performance of the lithium ion battery.
Disclosure of Invention
In view of the defects of the prior art, the invention aims to provide a lithium ion battery nonaqueous electrolyte and a lithium ion battery. According to the invention, by regulating and controlling the Electrolyte formula, the lithium salt additive and the silane additive are subjected to synergistic action, the problem that the high-content lithium bis (fluorosulfonyl) imide corrodes an aluminum foil in the battery circulation process is solved, and a stable Solid Electrolyte Interface (SEI) can be formed on the surface of the positive electrode material. In order to further reduce film forming impedance and change an SEI film structure, the invention introduces the sulfite additive, so that the ternary cathode material system meets the performance requirements of low-temperature power, high-temperature circulation, storage and the like.
In order to achieve the purpose, the invention adopts the following technical scheme:
in a first aspect, the invention provides a lithium ion battery non-aqueous electrolyte, which comprises a composite lithium salt, a non-aqueous solvent and additives, wherein the additives comprise a lithium salt additive, a silane additive and a sulfite additive;
the composite lithium salt comprises lithium bis (fluorosulfonyl) imide and auxiliary salt.
According to the invention, the synergistic effect of the lithium salt additive and the silane additive is utilized, so that passivation reaction can be carried out on the surfaces of the aluminum foil and the positive and negative electrode materials when the battery is charged, and the formed passivation film is beneficial to inhibiting further corrosion of the lithium bifluoride sulfimide under high potential to the aluminum foil, and also keeps the characteristics of thinness and stability, thereby improving the high-temperature circulation and high-temperature storage performance of the high-content lithium bifluoride sulfimide electrolyte system; in addition, the sulfite additive can react on the surfaces of the positive and negative electrodes to form a product similar to EC-Li+Interfacial film in complex state, reduced Li+The desolvation energy of the battery can further improve the cycle performance and the rate capability of a high-power battery system.
Preferably, the additive further comprises a carbonate-based additive.
Preferably, the carbonate-based additive comprises vinylene carbonate or/and fluoroethylene carbonate, and may be, for example, vinylene carbonate and fluoroethylene carbonate, vinylene carbonate or fluoroethylene carbonate.
Preferably, the carbonate additive is contained in the non-aqueous electrolyte of the lithium ion battery in an amount of 0.1 to 2% by mass, for example, 0.1%, 0.5%, 0.7%, 0.9%, 1.2%, 1.5% or 2% by mass, but not limited to the recited values, and other values not recited in the range of values are also applicable.
Preferably, the co-salt is lithium hexafluorophosphate.
Preferably, the molar ratio of lithium hexafluorophosphate to lithium bis-fluorosulfonylimide in said complex lithium salt is (0-1):1, for example 0:1, 0.2:1, 0.5:1, 0.8:1 or 1:1, but not limited to the values recited, and other values not recited in the numerical ranges are equally applicable.
Preferably, the concentration of the composite lithium salt in the non-aqueous electrolyte solution of the lithium ion battery is 1 to 1.5mol/L, for example, 1mol/L, 1.1mol/L, 1.2mol/L, 1.3mol/L, 1.4mol/L or 1.5mol/L, but not limited to the enumerated values, and other unrecited values in the numerical range are also applicable.
Preferably, the lithium salt additive includes any one or a combination of at least two of lithium tetrafluoroborate, lithium difluorophosphate, lithium bis (oxalato) borate, and lithium bis (oxalato) borate, such as lithium tetrafluoroborate and lithium difluorophosphate, lithium bis (oxalato) borate, or lithium bis (oxalato) borate, but not limited to the listed species, and other species not listed within the scope of the lithium salt additive are equally applicable.
Preferably, the lithium salt additive is contained in the non-aqueous electrolyte of the lithium ion battery in an amount of 0.5 to 2% by mass, for example, 0.5%, 0.7%, 0.9%, 1.2%, 1.5% or 2% by mass, but not limited to the recited values, and other values not recited in the numerical range are also applicable.
Preferably, the silane additive comprises any one of trimethylsilyl borate or trimethylsilyl phosphate.
Preferably, the content of the silane additive in the non-aqueous electrolyte solution of the lithium ion battery is 0.1-1% by mass, for example, 0.1%, 0.2%, 0.5%, 0.8% or 1%, but not limited to the recited values, and other values not recited in the numerical range are also applicable.
Preferably, the sulfite additive includes any one of vinyl sulfite, dimethyl sulfite, or diethyl sulfite.
Preferably, the content of the sulfite additive in the non-aqueous electrolyte of the lithium ion battery is 1 to 2% by mass, for example, 1%, 1.2%, 1.5%, 1.8% or 2%, but not limited to the recited values, and other values not recited in the numerical range are also applicable.
Preferably, the non-aqueous solvent includes a cyclic carbonate solvent and a chain carbonate solvent.
Preferably, the content of the nonaqueous solvent in the nonaqueous electrolyte solution of the lithium ion battery is 80 to 85% by mass, for example, 80%, 81%, 82%, 83%, 84% or 85%, but the present invention is not limited to the recited values, and other values not recited in the numerical range are also applicable.
Preferably, the cyclic carbonate solvent comprises either ethylene carbonate or propylene carbonate or a combination of both, and may be, for example, ethylene carbonate and propylene carbonate, ethylene carbonate or propylene carbonate.
Preferably, the chain carbonate solvent includes a combination of any two or three of dimethyl carbonate, diethyl carbonate or ethyl methyl carbonate, and may be, for example, ethyl methyl carbonate, dimethyl carbonate and diethyl carbonate, ethyl methyl carbonate and dimethyl carbonate or dimethyl carbonate and diethyl carbonate.
Preferably, the mass ratio of the cyclic carbonate solvent to the chain carbonate solvent in the nonaqueous solvent is 1 (1.5-4), and may be, for example, 1:1.5, 1:2, 1:2.5, 1:3 or 1:4, but is not limited to the enumerated values, and other values not enumerated within the numerical range are also applicable.
In a second aspect, the invention provides a lithium ion battery comprising the lithium ion battery nonaqueous electrolyte according to the first aspect.
Compared with the prior art, the invention has the following beneficial effects:
the invention solves the problem that the lithium bifluorosulfonyl imide is used as a main salt to corrode an aluminum foil in a high-power battery system, compounds a used lithium salt additive and a used silane additive by adjusting the formula of an electrolyte, preferentially forms a passivation layer on the surface of the aluminum foil, and improves the high-temperature circulation, high-temperature storage and low-temperature power performance of the high-power battery by the synergistic use of high-content lithium bifluorosulfonyl imide and a sulfite additive for reducing the desolvation performance of lithium ions and further preferentially adding a carbonate additive for improving the circulation.
Detailed Description
The technical solution of the present invention is further explained by the following embodiments. It should be understood by those skilled in the art that the examples are only for the understanding of the present invention and should not be construed as the specific limitations of the present invention.
Example 1
The embodiment provides a lithium ion battery nonaqueous electrolyte, which comprises 1% by mass of lithium tetrafluoroborate, 0.5% by mass of vinylene carbonate, 1.5% by mass of dimethyl sulfite and 0.5% by mass of an additive of trimethylsilyl borate, wherein the composite lithium salt comprises lithium bis (fluorosulfonyl) imide and 0.2mol/L of lithium hexafluorophosphate, and the nonaqueous solvent comprises 24% by mass of ethylene carbonate, 42% by mass of ethyl methyl carbonate and 16% by mass of diethyl carbonate, based on 100% by mass of the total mass of the nonaqueous electrolyte.
The preparation method of the non-aqueous electrolyte of the lithium ion battery comprises the following steps:
the electrolyte is prepared in a glove box, the nitrogen content in the glove box is 99.999 percent, the actual oxygen content in the glove box is less than 1ppm, and the moisture content is less than 1 ppm. Uniformly mixing 24% of ethylene carbonate, 42% of ethyl methyl carbonate and 16% of diethyl carbonate battery grade organic solvent by mass percentage based on 100% of the total mass of the nonaqueous electrolytic solution, adding fully dried lithium bis (fluorosulfonyl) imide and lithium hexafluorophosphate into the nonaqueous solvent, and adding 1% of lithium tetrafluoroborate, 0.5% of vinylene carbonate, 1.5% of dimethyl sulfite and 0.5% of trimethylsilyl borate by mass percentage respectively to enable the concentration of the lithium bis (fluorosulfonyl) imide to be 0.8mol/L and the concentration of the lithium hexafluorophosphate to be 0.2mol/L, thereby preparing the lithium ion battery nonaqueous electrolytic solution.
The preparation method of the lithium ion battery comprises the following steps:
preparing a positive plate: dissolving a positive active material NCM523, a conductive agent acetylene black and an adhesive polyvinylidene fluoride in a solvent N-methyl pyrrolidone according to a mass ratio of 93:4:3, and uniformly mixing to prepare positive slurry, wherein the solid content in the positive slurry is 67%. And then uniformly coating the positive electrode slurry on a current collector aluminum foil, drying at 120 ℃, then performing cold pressing and cutting, and drying at 145 ℃ for 8h under a vacuum condition to prepare the positive electrode plate of the lithium ion battery.
Preparing a negative plate: dissolving a negative electrode active material graphite, a conductive agent acetylene black, a thickening agent sodium carboxymethyl cellulose and an adhesive butadiene styrene rubber in a solvent deionized water according to a mass ratio of 95:2:2:1, and uniformly mixing to prepare a negative electrode slurry, wherein the solid content in the negative electrode slurry is 52%. And then uniformly coating the negative electrode slurry on the front surface and the back surface of the current collector copper foil, drying at 85 ℃, then performing cold pressing and cutting, and drying at 120 ℃ for 8 hours under a vacuum condition to prepare the negative electrode plate of the lithium ion battery.
Stacking the positive plate, the lithium battery isolation film and the negative plate in sequence to enable the lithium battery isolation film to be positioned between the positive plate and the negative plate to play an isolation role, and then winding to obtain a bare cell; and placing the bare cell in an outer packaging foil, injecting the prepared electrolyte into the dried battery, and performing vacuum packaging, standing, formation, aging and other processes to obtain the lithium ion battery.
Example 2
The embodiment provides a lithium ion battery nonaqueous electrolyte, which comprises 0.5 mass percent of lithium tetrafluoroborate, 0.5 mass percent of vinylene carbonate, 1 mass percent of dimethyl sulfite and 0.1 mass percent of trimethylsilyl borate as additives based on the total mass of the nonaqueous electrolyte being 100 percent, wherein a composite lithium salt comprises lithium bis (fluorosulfonyl) imide with the concentration of 0.8mol/L and 0.2mol/L of lithium hexafluorophosphate, and the nonaqueous solvent comprises 25.5 mass percent of ethylene carbonate, 37.4 mass percent of ethyl methyl carbonate and 20.5 mass percent of diethyl carbonate.
The preparation method of the non-aqueous electrolyte of the lithium ion battery comprises the following steps:
the electrolyte is prepared in a glove box, the nitrogen content in the glove box is 99.999 percent, the actual oxygen content in the glove box is less than 1ppm, and the moisture content is less than 1 ppm. Uniformly mixing 25.5 percent by mass of ethylene carbonate, 37.4 percent by mass of ethyl methyl carbonate and 20.5 percent by mass of diethyl carbonate battery-grade organic solvent by taking the total mass of the nonaqueous electrolyte as 100 percent, adding fully dried lithium bifluorosulfonyl imide and lithium hexafluorophosphate into the nonaqueous solvent, and adding 0.5 percent by mass of lithium tetrafluoroborate, 0.5 percent by mass of vinylene carbonate, 1 percent by mass of dimethyl sulfite and 0.1 percent by mass of trimethylsilyl borate as additives to ensure that the concentration of the lithium bifluorosulfonyl imide is 0.8mol/L and the concentration of the lithium hexafluorophosphate is 0.2mol/L respectively, thus preparing the nonaqueous electrolyte for the lithium ion battery.
The preparation method of the lithium ion battery comprises the following steps:
the preparation method of the lithium ion battery of the present example is the same as that of example 1.
Example 3
The embodiment provides a lithium ion battery nonaqueous electrolyte, which comprises 1% by mass of lithium tetrafluoroborate, 0.3% by mass of vinylene carbonate, 1.5% by mass of dimethyl sulfite and 1% by mass of trimethylsilyl borate respectively based on 100% by mass of the total mass of the nonaqueous electrolyte, wherein a composite lithium salt comprises lithium bis (fluorosulfonyl) imide with a concentration of 0.8mol/L and 0.2mol/L of lithium hexafluorophosphate, and a nonaqueous solvent comprises 24.2% by mass of ethylene carbonate, 40% by mass of ethyl methyl carbonate and 17.5% by mass of diethyl carbonate.
The preparation method of the non-aqueous electrolyte of the lithium ion battery comprises the following steps:
the electrolyte is prepared in a glove box, the nitrogen content in the glove box is 99.999 percent, the actual oxygen content in the glove box is less than 1ppm, and the moisture content is less than 1 ppm. Uniformly mixing 24.2% of ethylene carbonate, 40% of ethyl methyl carbonate and 17.5% of diethyl carbonate battery grade organic solvent by mass percentage based on 100% of the total mass of the nonaqueous electrolytic solution, adding fully dried lithium bis (fluorosulfonyl) imide and lithium hexafluorophosphate into the nonaqueous solvent, and adding 1% of lithium tetrafluoroborate, 0.3% of vinylene carbonate, 1.5% of dimethyl sulfite and 1% of trimethylsilyl borate by mass percentage respectively to enable the concentration of lithium bis (fluorosulfonyl) imide to be 0.8mol/L and the concentration of lithium hexafluorophosphate to be 0.2mol/L, and preparing the lithium ion battery nonaqueous electrolytic solution.
The preparation method of the lithium ion battery comprises the following steps:
the preparation method of the lithium ion battery of the present example is the same as that of example 1.
Example 4
The embodiment provides a lithium ion battery nonaqueous electrolyte, wherein the lithium ion nonaqueous electrolyte comprises 0.8 mass percent of lithium tetrafluoroborate, 1.5 mass percent of dimethyl sulfite and 0.5 mass percent of trimethylsilyl borate as additives respectively based on the total mass of the nonaqueous electrolyte as 100 percent, a composite lithium salt comprises 0.8mol/L lithium bis-fluorosulfonylimide and 0.2mol/L lithium hexafluorophosphate, and a nonaqueous solvent comprises 25.2 mass percent of ethylene carbonate, 50 mass percent of ethyl methyl carbonate and 7.5 mass percent of diethyl carbonate.
The preparation method of the non-aqueous electrolyte of the lithium ion battery comprises the following steps:
the electrolyte is prepared in a glove box, the nitrogen content in the glove box is 99.999 percent, the actual oxygen content in the glove box is less than 1ppm, and the moisture content is less than 1 ppm. Uniformly mixing 25.2% of ethylene carbonate, 50% of ethyl methyl carbonate and 7.5% of diethyl carbonate battery grade organic solvent by mass percentage based on 100% of the total mass of the nonaqueous electrolytic solution, adding fully dried lithium bifluorosulfonyl imide and lithium hexafluorophosphate into the nonaqueous solvent, and adding 0.8% of lithium tetrafluoroborate, 1.5% of dimethyl sulfite and 0.5% of trimethylsilyl borate additive by mass percentage respectively to enable the concentration of the lithium bifluorosulfonyl imide to be 0.8mol/L and the concentration of the lithium hexafluorophosphate to be 0.2mol/L, and preparing the lithium ion battery nonaqueous electrolytic solution.
The preparation method of the lithium ion battery comprises the following steps:
the preparation method of the lithium ion battery of the present example is the same as that of example 1.
Example 5
This example differs from example 1 in that dimethyl sulfite is replaced with vinyl sulfite, and the rest is the same as example 1.
Example 6
This example differs from example 1 in that the trimethylsilyl borate ester is replaced with trimethylsilyl phosphate ester, and the rest is the same as example 1.
Example 7
The embodiment provides a lithium ion battery nonaqueous electrolyte, wherein the lithium ion nonaqueous electrolyte comprises 0.25 mass percent of lithium tetrafluoroborate, 0.5 mass percent of lithium difluorobis (oxalato) borate, 1 mass percent of fluoroethylene carbonate, 1 mass percent of dimethyl sulfite and 0.5 mass percent of trimethylsilyl borate respectively based on 100 mass percent of the total mass of the nonaqueous electrolyte, a composite lithium salt comprises 0.7mol/L lithium difluorosulfonimide and 0.3mol/L lithium hexafluorophosphate, and the nonaqueous solvent comprises 24.5 mass percent of ethylene carbonate, 48 mass percent of ethyl methyl carbonate and 10 mass percent of diethyl carbonate.
The preparation method of the non-aqueous electrolyte of the lithium ion battery comprises the following steps:
the electrolyte is prepared in a glove box, the nitrogen content in the glove box is 99.999 percent, the actual oxygen content in the glove box is less than 1ppm, and the moisture content is less than 1 ppm. Uniformly mixing 24.5 percent by mass of ethylene carbonate, 48 percent by mass of ethyl methyl carbonate and 10 percent by mass of diethyl carbonate battery-grade organic solvent by taking the total mass of the nonaqueous electrolytic solution as 100 percent, adding fully dried lithium bis (fluorosulfonyl) imide and lithium hexafluorophosphate into the nonaqueous solvent, and adding additives of 0.25 percent by mass of lithium tetrafluoroborate, 0.5 percent by mass of lithium difluorobis (oxalato) borate, 1 percent by mass of fluoroethylene carbonate, 1 percent by mass of dimethyl sulfite and 0.5 percent by mass of trimethylsilyl borate respectively to enable the concentration of the lithium bis (fluorosulfonyl) imide to be 0.7mol/L and the concentration of the lithium hexafluorophosphate to be 0.3mol/L, and preparing the nonaqueous electrolytic solution for the lithium ion battery.
The preparation method of the lithium ion battery comprises the following steps:
the preparation method of the lithium ion battery of the present example is the same as that of example 1.
Example 8
The embodiment provides a lithium ion battery nonaqueous electrolyte, wherein the lithium ion nonaqueous electrolyte comprises additives of 0.1% by mass of lithium tetrafluoroborate, 0.5% by mass of lithium bis (oxalato) borate, 1% by mass of fluoroethylene carbonate, 1% by mass of diethyl sulfite and 1% by mass of trimethylsilyl phosphate respectively, a composite lithium salt comprises 0.8mol/L lithium bis (fluorosulfonato) imide and 0.2mol/L lithium hexafluorophosphate, and a nonaqueous solvent comprises 25.4% by mass of ethylene carbonate, 50% by mass of ethyl methyl carbonate and 6.5% by mass of diethyl carbonate, based on 100% by mass of the total mass of the nonaqueous electrolyte.
The preparation method of the non-aqueous electrolyte of the lithium ion battery comprises the following steps:
the electrolyte is prepared in a glove box, the nitrogen content in the glove box is 99.999 percent, the actual oxygen content in the glove box is less than 1ppm, and the moisture content is less than 1 ppm. Uniformly mixing 25.4% of ethylene carbonate, 50% of ethyl methyl carbonate and 6.5% of diethyl carbonate battery grade organic solvent by mass percentage based on 100% of the total mass of the nonaqueous electrolyte, adding fully dried lithium bifluorosulfonyl imide and lithium hexafluorophosphate into the nonaqueous solvent, and adding additives of 0.1% of lithium tetrafluoroborate, 0.5% of lithium bis oxalato borate, 1% of fluoroethylene carbonate, 1% of diethyl sulfite and 1% of trimethylsilyl phosphate by mass percentage to enable the concentration of lithium bifluorosulfonyl imide to be 0.8mol/L and the concentration of lithium hexafluorophosphate to be 0.2mol/L respectively, and preparing the lithium ion battery nonaqueous electrolyte.
The preparation method of the lithium ion battery comprises the following steps:
the preparation method of the lithium ion battery of the present example is the same as that of example 1.
Comparative example 1
This comparative example is different from example 7 in that trimethylsilyl borate was replaced with ethyl methyl carbonate in an equal mass percentage based on 100% by mass of the total mass of the nonaqueous electrolytic solution, and the rest was the same as example 7.
Comparative example 2
This comparative example is different from example 7 in that 0.25% by mass of lithium tetrafluoroborate and 0.5% by mass of lithium difluorobis (oxalato) borate were replaced with 0.75% by mass of lithium bistrifluoromethylsulfonimide, based on 100% by mass of the total mass of the nonaqueous electrolytic solution, and the remainder was the same as example 7.
Comparative example 3
This comparative example is different from example 7 in that dimethyl sulfite was replaced with ethyl methyl carbonate in an equal mass percentage based on 100% by mass of the total mass of the nonaqueous electrolytic solution, and the remainder was the same as example 7.
Table 1:
test conditions
The lithium ion batteries prepared in examples 1 to 8 and comparative examples 1 to 3 were subjected to high temperature cycle, high temperature storage and low temperature power performance tests, respectively, the test methods were as follows:
(1) and (3) high-temperature storage test: the cell is placed at room temperature to carry out 5 times of charge-discharge cycle tests with an electrochemical window of 2.8-4.2V at a charge-discharge multiplying factor of 1C, then the 1C multiplying factor is charged to a full state of 4.2V, and the 1C capacity Q is recorded respectively0And battery volume V0. Storing the battery in full charge state at 60 deg.C for 90 days, and recording the volume V of the battery1And 1C discharge capacity Q1Then charging and discharging the battery at room temperature at a rate of 1C of 2.8-4.2V for 5 weeks, and recording the 1C discharge capacity Q2And calculating to obtain experimental data such as the high-temperature storage capacity retention rate, the capacity recovery rate, the volume change rate and the like of the battery, and recording the results as shown in table 2. Calculating the capacity retention rate, the capacity recovery rate and the volume change rate of the battery according to the following formulas:
capacity retention (%) ═ Q1/Q0×100％
Capacity recovery rate (%) ═ Q2/Q0×100％
Volume change rate (%) - (V)1-V0)/V0×100％
(2) High-temperature cycle test: the cell was left at 45 ℃ and the initial capacity was recorded as A1The capacity of the electrochemical window of 2.8-4.2V for circulating to 1000 weeks is A with the charge-discharge multiplying power of 2C/2C2The capacity retention rate of the battery after high-temperature cycling for 1000 weeks is calculated according to the following formula:
cycle capacity retention (%) ═ a2/A1×100％
(3) And (3) low-temperature power performance test: the cell with the charge state of 50% is placed at-20 ℃ for standing for 2h, and then is discharged for 10s by using the rate of 10C to obtain the voltage of the cell.
The test results are shown in table 2:
table 2:
as can be seen from the data in table 2, compared with comparative examples 1 and 2, the lithium salt additive and the silane additive are added in examples 1 to 8, so that the cycle capacity retention rate of the prepared lithium ion battery at 45 ℃ is up to more than 82%, and meanwhile, the capacity retention rate and the capacity recovery rate of the lithium ion battery stored at a high temperature of 60 ℃ are significantly improved, the capacity retention rate is not lower than 83%, and the capacity recovery rate is not lower than 85%. Compared with the comparative examples 1 and 2 without the lithium salt additive or the silane additive, the high-temperature storage and high-temperature cycle performance of the lithium ion battery is inferior to that of the examples 1-8, and the synergistic effect of the lithium salt additive and the silane additive is further shown, so that the high-temperature storage and cycle performance of a high-power battery system taking LiFSI as a main salt is greatly improved.
As can be seen from the data in Table 2, the low-temperature power was improved and the cycle and storage performance of the lithium ion battery was not deteriorated in examples 1 to 8 compared to comparative example 3 due to the addition of the sulfite-based additive. The low-temperature power performance can be further improved by changing the film forming structure effect of the sulfite additive, and the high-temperature storage, high-temperature circulation and low-temperature power characteristics of the lithium ion battery are improved by the synergistic effect of the sulfite additive, the lithium salt additive and the silane additive.
The applicant states that the present invention is described by the above examples for the nonaqueous electrolyte solution for lithium ion batteries, but the present invention is not limited to the above examples, that is, the present invention is not meant to be implemented by relying on the above examples. It should be understood by those skilled in the art that any modification of the present invention, equivalent substitutions of the raw materials of the product of the present invention, addition of auxiliary components, selection of specific modes, etc., are within the scope and disclosure of the present invention.
Claims (10)
1. The non-aqueous electrolyte of the lithium ion battery is characterized by comprising a composite lithium salt, a non-aqueous solvent and additives, wherein the additives comprise a lithium salt additive, a silane additive and a sulfite additive;
the composite lithium salt comprises lithium bis (fluorosulfonyl) imide and auxiliary salt.
2. The nonaqueous electrolyte solution for a lithium ion battery according to claim 1, wherein the additive further comprises a carbonate-based additive;
preferably, the carbonate additive comprises vinylene carbonate or/and fluoroethylene carbonate;
preferably, the mass percentage content of the carbonate additive in the non-aqueous electrolyte of the lithium ion battery is 0.1-2%.
3. The nonaqueous electrolyte solution for lithium ion batteries according to claim 1 or 2, wherein the auxiliary salt is lithium hexafluorophosphate;
preferably, the molar ratio of the lithium hexafluorophosphate to the lithium bis (fluorosulfonyl) imide in the composite lithium salt is (0-1): 1;
preferably, the concentration of the composite lithium salt in the non-aqueous electrolyte of the lithium ion battery is 1-1.5 mol/L.
4. The nonaqueous electrolyte solution for a lithium ion battery according to any one of claims 1 to 3, wherein the lithium salt additive comprises any one of lithium tetrafluoroborate, lithium difluorophosphate, lithium bis (oxalato) borate, lithium difluoro (oxalato) borate, or a combination of at least two thereof;
preferably, the lithium salt additive in the non-aqueous electrolyte of the lithium ion battery is 0.5-2% by mass.
5. The nonaqueous electrolyte solution for a lithium ion battery according to any one of claims 1 to 4, wherein the silane additive comprises any one of trimethylsilyl borate or trimethylsilyl phosphate;
preferably, the mass percentage of the silane additive in the lithium ion battery non-aqueous electrolyte is 0.1-1%.
6. The nonaqueous electrolyte for a lithium-ion battery according to any one of claims 1 to 5, wherein the sulfite additive includes any one of a vinyl sulfite, a dimethyl sulfite, or a diethyl sulfite;
preferably, the mass percentage of the sulfite additive in the lithium ion battery non-aqueous electrolyte is 1-2%.
7. The nonaqueous electrolyte for a lithium-ion battery according to any one of claims 1 to 6, wherein the nonaqueous solvent includes a cyclic carbonate solvent and a chain carbonate solvent;
preferably, the mass percentage of the nonaqueous solvent in the nonaqueous electrolyte of the lithium ion battery is 80-85%.
8. The nonaqueous electrolyte solution for a lithium ion battery according to claim 7, wherein the cyclic carbonate solvent comprises either one of ethylene carbonate or propylene carbonate or a combination of both;
preferably, the chain carbonate solvent comprises a combination of any two or three of dimethyl carbonate, diethyl carbonate or ethyl methyl carbonate.
9. The nonaqueous electrolyte solution for lithium ion batteries according to claim 7 or 8, wherein the mass ratio of the cyclic carbonate solvent to the chain carbonate solvent in the nonaqueous solvent is 1 (1.5-4).
10. A lithium ion battery, characterized in that the lithium ion battery comprises the lithium ion battery nonaqueous electrolyte according to any one of claims 1 to 9.
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114678527A (en) * | 2022-03-21 | 2022-06-28 | 珠海冠宇电池股份有限公司 | Battery with improved battery capacity |
| CN115513528A (en) * | 2022-11-21 | 2022-12-23 | 广州天赐高新材料股份有限公司 | Nonaqueous electrolyte solution and secondary battery |
| CN115663392A (en) * | 2022-11-01 | 2023-01-31 | 湖北骅驰新能源材料有限公司 | Electrolyte film-forming additive and lithium ion battery electrolyte containing same |
| WO2023221120A1 (en) * | 2022-05-20 | 2023-11-23 | 宁德时代新能源科技股份有限公司 | Non-aqueous electrolyte, secondary battery comprising same, battery module, battery pack, and electric device |
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2021
- 2021-11-24 CN CN202111406054.4A patent/CN114142091A/en active Pending
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114678527A (en) * | 2022-03-21 | 2022-06-28 | 珠海冠宇电池股份有限公司 | Battery with improved battery capacity |
| WO2023221120A1 (en) * | 2022-05-20 | 2023-11-23 | 宁德时代新能源科技股份有限公司 | Non-aqueous electrolyte, secondary battery comprising same, battery module, battery pack, and electric device |
| CN115663392A (en) * | 2022-11-01 | 2023-01-31 | 湖北骅驰新能源材料有限公司 | Electrolyte film-forming additive and lithium ion battery electrolyte containing same |
| CN115513528A (en) * | 2022-11-21 | 2022-12-23 | 广州天赐高新材料股份有限公司 | Nonaqueous electrolyte solution and secondary battery |
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