CN114512721A - Lithium ion battery non-aqueous electrolyte and lithium ion battery - Google Patents

Lithium ion battery non-aqueous electrolyte and lithium ion battery Download PDF

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CN114512721A
CN114512721A CN202210149798.0A CN202210149798A CN114512721A CN 114512721 A CN114512721 A CN 114512721A CN 202210149798 A CN202210149798 A CN 202210149798A CN 114512721 A CN114512721 A CN 114512721A
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lithium ion
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程梅笑
申海鹏
郑畅
郭营军
李新丽
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Xianghe Kunlun New Energy Materials Co ltd
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    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00Secondary cells; Manufacture thereof
    • H01M10/05Accumulators with non-aqueous electrolyte
    • H01M10/056Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564Accumulators 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
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    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00Secondary cells; Manufacture thereof
    • H01M10/05Accumulators with non-aqueous electrolyte
    • H01M10/052Li-accumulators
    • H01M10/0525Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00Secondary cells; Manufacture thereof
    • H01M10/05Accumulators with non-aqueous electrolyte
    • H01M10/058Construction or manufacture
    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01MPROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
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    • H01M10/42Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
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Abstract

The invention provides a lithium ion battery non-aqueous electrolyte and a lithium ion battery. According to the invention, the alkenyl siloxane compound with the cyclic structure and the borosiloxane compound with the cyclic structure are added into the electrolyte, so that stable SEI films can be formed on the surfaces of the anode electrode material and the cathode electrode material, and good long-cycle stability, storage capacity retention rate and recovery rate and smaller battery volume expansion can be maintained under a high-temperature environment.

Description

Lithium ion battery non-aqueous electrolyte and lithium ion battery
Technical Field
The invention belongs to the technical field of lithium ion batteries, and relates to a lithium ion battery non-aqueous electrolyte and a lithium ion battery.
Background
The improvement of the battery voltage is one of the important methods for improving the energy density of the battery, but the battery performance caused by high voltage is also outstanding, for example, the battery is easy to collapse to cause lithium precipitation due to the negative electrode structure, the transition metal ions are dissolved out to further catalyze the decomposition of the electrolyte to generate gas, the crystal structure is collapsed due to oxygen release of the positive electrode, and the like, so that the long cycle performance and the storage performance of the battery are affected.
CN109755648A discloses an electrolyte, which can remarkably improve the safety performance, storage performance and cycle performance of a battery under a high voltage condition by adding two components of benzothiophene compound and trialkoxyboroxine for synergistic action; the trialkoxyboroxine can form a film on the anode preferentially, so that the anode is effectively protected, meanwhile, boron atoms in the trialkoxyboroxine can coordinate with oxygen atoms in a cathode material, the cathode material is further protected, the benzothiophene compound forms a film on the anode, and the storage performance and the cycle performance of the electrolyte under the high-voltage condition are obviously improved under the synergistic effect of the trialkoxyboroxine and the cathode material. However, this invention does not complex metal ions eluted from the positive electrode, has only 100-cycle performance, and cannot suppress capacity fading of a long-cycle battery.
Therefore, in the art, it is desired to develop a material capable of solving the battery safety problems induced by the excessive capacity retention rate and recovery rate fading, the excessive high-temperature long-cycle capacity fading, and the volume expansion under the high-temperature environment in the high-temperature storage of the high-voltage lithium ion battery.
Disclosure of Invention
In view of the defects of the prior art, the invention aims to provide a lithium ion battery non-aqueous electrolyte and a lithium ion battery, and particularly provides a high-voltage lithium ion battery non-aqueous electrolyte and a lithium ion battery. The non-aqueous electrolyte of the lithium ion battery is suitable for a high-voltage lithium ion battery, can solve the problems of overlarge capacity retention rate and recovery rate attenuation, too quick high-temperature long-cycle capacity attenuation and battery safety caused by volume expansion in a high-temperature environment in the high-temperature storage of the conventional high-voltage lithium ion battery, and particularly can show excellent electrochemical performance in a silicon-carbon/silicon-oxygen cathode material battery with high energy density or a high-nickel high-voltage battery system.
In order to achieve the purpose, the invention adopts the following technical scheme:
in one aspect, the present invention provides a lithium ion battery nonaqueous electrolyte comprising a lithium salt electrolyte, a nonaqueous solvent, and an additive comprising at least one cyclic alkenylsiloxane compound having a structure represented by formula (1) and at least one cyclic boroxine compound having a structure represented by formula (2):
Figure BDA0003510289640000021
wherein R is1Selected from hydrogen, halogen, cyano, substituted or unsubstituted C1-C5 alkyl, substituted or unsubstituted C6-C30 aryl, amido, phosphate, sulfonyl, siloxy or borate, n is an integer of 3-10 (e.g., 3, 4, 5, 6, 7, 8, 9 or 10); r2Selected from hydrogen, halogen, substituted or unsubstituted C1-C5 alkyl, substituted or unsubstituted C6-C30 aryl, and m is an integer of 3-10 (e.g., 3, 4, 5, 6, 7, 8, 9 or 10).
In the invention, the alkyl group of C1-C5 can be C1, C2, C3, C4 or C5.
The aryl of C6-C30 can be C6, C8, C10, C12, C16, C18, C20, C22, C24, C26, C28 or C29.
Preferably, when a group as defined above is said group substituted, the substituent is selected from at least one of halogen, C1-C6 (e.g. C1, C2, C3, C4, C5 or C6) alkyl or C1-C6 (e.g. C1, C2, C3, C4, C5 or C6) alkoxy.
In the present invention, the inventors found that the key means for solving the problem is: when the cyclic alkenyl siloxane compound of the formula (1) and the cyclic borosiloxane compound of the formula (2) are combined in the electrolyte, stable solid electrolyte interface films can be formed on the surfaces of the positive electrode and the negative electrode of the lithium ion battery, the ion conductivity of the interface films is excellent, the lithium ion impedance is reduced, the capacity retention rate and the recovery rate are high in a high-temperature storage environment, the capacity fading speed is reduced in the charging and discharging process, and the volume expansion of the battery is inhibited in the high-temperature environment.
Although there is no mechanism for proving the electrochemical stability of the cyclic alkenylsiloxane compound of formula (1) and the cyclic borosiloxane compound of formula (2) in the electrolyte solution of the present invention, the inventors can reasonably speculate that: the double bonds of the formula (1) are broken at the initial stage of the electrochemical reaction process, a compact solid electrolyte interface film can be formed on the positive electrode and the negative electrode, meanwhile, the formula (2) can also be opened to participate in film formation, the ion compactness and stability of the interface film at the moment are enhanced, the interface film cannot be damaged under the conditions of high voltage and high temperature, further, less active lithium ions are consumed, and the capacity of the high-voltage lithium ion battery is ensured. Meanwhile, the-Si-O-bond can complex metal ions dissolved out from the anode, so that the catalytic reaction of the metal ions on the electrolyte is further reduced, Si atoms are easy to adsorb fluoride ions, and the decomposition of lithium salt is inhibited; the B atom can be coordinated with an oxygen atom in the anode material, so that the crystal structure of the anode material is stabilized, and the stability of the anode in the charge and discharge processes is protected.
Preferably, the cyclic alkenylsiloxane compound having the structure represented by formula (1) is any one of 2,4,6, 8-tetramethyl-2, 4,6, 8-tetravinylcyclotetrasiloxane (abbreviated as TTCS), 2,4,4,6,6,8, 8-octa (vinyl) -1,3,5,7,2,4,6, 8-tetraoxatetrasiloxane (abbreviated as OTTS), tetramethyltetravinylcyclotetrasiloxane (abbreviated as ViD4), or tetravinyltetraphenylcyclotetrasiloxane (abbreviated as TMTPS).
Preferably, the cyclic boroxine compound represented by formula (2) is any one of the following compounds:
Figure BDA0003510289640000041
preferably, the content of the cyclic alkenylsiloxane compound having the structure represented by formula (1) is 0.01 to 5% (e.g., 0.01%, 0.05%, 1%, 3%, or 5%) and the content of the cyclic borosiloxane compound having the structure represented by formula (2) is 0.01 to 5% (e.g., 0.01%, 0.05%, 1%, 3%, or 5%) based on 100% by mass of the total nonaqueous electrolyte solution of the lithium ion battery.
Preferably, the additive further comprises other additives, the other additives comprise one or a combination of at least two of lithium difluorophosphate, vinyl sulfate, vinyl fluorocarbonate, 1, 3-propane sultone, ethylene glycol dipropionitrile ether, 1,3, 6-hexanetricarbonitrile, succinonitrile, adiponitrile, lithium difluorobis (oxalato) phosphate, or 1,1,2, 3-tetrafluoroethyl-2, 2,3, 3-tetrafluoropropyl ether.
Preferably, the content of the other additive is 0.01 to 25%, for example, 0.01%, 0.05%, 1%, 3%, 5%, 8%, 10%, 13%, 15%, 20%, 22%, or 25% based on 100% by mass of the total nonaqueous electrolyte solution of the lithium ion battery.
Preferably, the lithium salt electrolyte comprises any one of lithium hexafluorophosphate, lithium perchlorate, lithium trifluoromethanesulfonate, lithium bis-fluorosulfonylimide or lithium bis-trifluoromethanesulfonimide or a combination of at least two thereof.
Preferably, the content of the lithium salt electrolyte is 2 to 25%, for example, 3%, 5%, 8%, 10%, 13%, 15%, 20%, 22% or 25% based on 100% by mass of the total mass of the lithium ion battery nonaqueous electrolyte solution.
Preferably, the non-aqueous solvent is one or a combination of at least two of ethylene glycol diethyl ether, methyl propionate (abbreviated as MP), methyl acetate (abbreviated as MA), propyl propionate (abbreviated as PP), methyl butyrate (abbreviated as MB), ethyl butyrate (abbreviated as EB), propyl acetate (abbreviated as PA), butyl butyrate (abbreviated as BB), acetonitrile (abbreviated as AN), methylpropyl carbonate (abbreviated as MPC), ethyl propionate (abbreviated as EP), γ -butyrolactone (abbreviated as GBL), sulfolane (abbreviated as SL), dimethyl sulfoxide, tetrahydrofuran, propylene carbonate (abbreviated as PC), ethyl acetate (abbreviated as EA), diethyl carbonate (abbreviated as DEC), methylethyl carbonate (abbreviated as EMC), dimethyl carbonate (abbreviated as DMC) and vinyl carbonate (abbreviated as EC).
Preferably, the content of the nonaqueous solvent is 40 to 92.98%, for example, 40%, 43%, 45%, 48%, 50%, 55%, 58%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 92%, or the like, based on 100% by mass of the total nonaqueous electrolyte of the lithium ion battery.
In another aspect, the invention also provides a lithium ion battery, which comprises the lithium ion battery nonaqueous electrolyte.
In the invention, the lithium ion battery comprises a battery shell, a battery cell and the lithium ion battery non-aqueous electrolyte, wherein the battery cell and the lithium ion battery non-aqueous electrolyte are sealed in the battery shell.
Preferably, the cell includes a positive electrode, a negative electrode, and a separator or a solid electrolyte layer disposed between the positive electrode and the negative electrode.
Preferably, the positive electrode includes an active material capable of inserting and extracting lithium, and the active material capable of inserting and extracting lithium is preferably a lithium transition metal composite oxide.
Preferably, the negative electrode includes a metal or alloy capable of inserting and extracting lithium or forming an alloy with lithium, or a metal oxide capable of inserting/extracting lithium.
Preferably, the active material capable of intercalating and deintercalating lithium is LiNixCoyMnzL(1-x-y-z)O2、LiCox'L(1-x')O2、LiNix”L'y'Mn(2-x”-y')O4、Liz'MPO4、LiMn2O4At least one of; wherein L is at least one of Al, Sr, Mg, Ti, Ca, Zr, Zn, Si and Fe; x is more than or equal to 0 and less than or equal to 1, y is more than or equal to 0 and less than or equal to 1, z is more than or equal to 0 and less than or equal to 1, x + y + z is more than 0 and less than or equal to 1, x ' is more than 0.3 and less than or equal to 0.6, y ' is more than or equal to 0.01 and less than or equal to 0.2, and L ' is at least one of Co, Al, Sr, Mg, Ti, Ca, Zr, Zn, Si or Fe; z' is more than or equal to 0.5 and less than or equal to 1, and M is at least one of Fe, Mn or Co.
Preferably, the material of the negative electrode includes crystalline carbon, lithium metal, SiO2Graphite composite, SiC/graphite composite, LiMnO2、LiAl、Li3Sb、Li3Cd、LiZn、Li3Bi、Li4Si、Li4.4Pb、Li4.4Sn、LiC6、Li3FeN2、Li2.6CoN0.4、Li2.6CuN0.4Or Li4Ti5O12At least one of (1).
Preferably, the charge cut-off voltage of the lithium ion battery of the present invention is not less than 3.6V, and may be, for example, 3.6V, 4.0V, 4.5V, 4.8V, 5.0V, or the like.
Preferably, the operating voltage of the lithium ion battery is 3.6V to 5V, and may be, for example, 3.6V, 4.0V, 4.5V, 4.8V, 5.0V, and preferably 4.35V to 4.8V.
Compared with the prior art, the invention has the following beneficial effects:
according to the invention, the alkenyl siloxane compound with the cyclic structure and the borosiloxane compound with the cyclic structure are added into the electrolyte, so that stable SEI films can be formed on the surfaces of the anode electrode material and the cathode electrode material, and good long-cycle stability, storage capacity retention rate and recovery rate and smaller battery volume expansion can be kept under a high-temperature environment, the capacity retention rate reaches more than 91% after 600 cycles at 45 ℃, the capacity retention rate reaches more than 90% after 60 ℃ high-temperature storage for 14 days, the capacity recovery rate reaches more than 91%, and the volume expansion rate is as low as less than 4.8%.
Drawings
FIG. 1 is a graph showing the results of testing the capacity retention of the batteries of examples 1-2 and comparative examples 1-2 at a high temperature of 45 ℃ for 600 cycles;
FIG. 2 is a graph showing the results of testing the capacity retention rate and recovery rate of the batteries of examples 1-2 and comparative examples 1-2 stored at a high temperature of 60 ℃ for 14 days;
fig. 3 is a graph showing the results of a test of the volume growth rate of the batteries of examples 1 to 2 and comparative examples 1 to 2 stored at a high temperature of 60 c for 14 days.
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
This example provides a high voltage lithium ion battery nonaqueous electrolyte comprising, based on 100% of the total mass of the nonaqueous electrolyte, 14.5% by mass of lithium hexafluorophosphate, 21.0% by mass of EC, 10.0% by mass of PC and 38.0% by mass of PP as a nonaqueous solvent, 5.00% by mass of 2,4,6, 8-tetramethyl-2, 4,6, 8-tetravinylcyclotetrasiloxane (TTCS) available from shanghai tai chemical industry co., ltd), 1.50% by mass of cyclic boroxane compound B01 available from shijia santitai chemical co., ltd), 9.00% by mass of vinyl fluorocarbonate available from Jiangsu Huasheng materials lty co., lty, and 1.00% by mass of vinyl sulfate (available from shijia santitai chemical co., lty).
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 2ppm, and the moisture content is less than 0.1 ppm. Based on the total mass of the nonaqueous electrolyte solution as 100%, uniformly mixing 21.0% by mass of EC, 10.0% by mass of PC and 38.0% by mass of PP battery-grade organic solvent, adding fully dried 14.5% by mass of lithium hexafluorophosphate into the nonaqueous solvent, adding 5.00% by mass of 2,4,6, 8-tetramethyl-2, 4,6, 8-tetravinylcyclotetrasiloxane and 1.50% by mass of B01, and adding 9.00% by mass of fluoroethylene carbonate and 1.00% by mass of vinyl sulfate to prepare the nonaqueous electrolyte solution of the lithium ion battery.
The preparation method of the lithium ion battery comprises the following steps:
preparing a positive electrode: subjecting LiCoO to condensation2Mixing the powder, a binder polyvinylidene fluoride (PVDF) and a conductive agent acetylene black according to a weight ratio of 97.5:1.5:1.5, adding N-methylpyrrolidone (NMP), and stirring under the action of a vacuum stirrer until a mixed system becomes uniform and flowable anode slurry; uniformly coating the positive electrode slurry on an aluminum foil with the thickness of 15 mu m; uniformly coating the positive electrode slurry on an aluminum foil with the thickness of 15 mu m; baking the coated aluminum foil in 5 sections of baking ovens with different temperature gradients, drying the aluminum foil in a baking oven at 120 ℃ for 8 hours, and rolling and cutting to obtain the required positive plate.
Preparing a negative electrode: preparing a graphite negative electrode material with the mass ratio of 95.7 wt%, a conductive carbon black (SP) conductive agent with the mass ratio of 1 wt%, a sodium carboxymethylcellulose (CMC) dispersing agent with the mass ratio of 1.3 wt% and a Styrene Butadiene Rubber (SBR) binder with the mass ratio of 2 wt% into negative electrode slurry by a wet process; uniformly coating the negative electrode slurry on a copper foil with the thickness of 15 mu m; and baking the coated copper foil in 5 sections of baking ovens with different temperature gradients, drying the copper foil in an oven at 85 ℃ for 5 hours, and rolling and slitting to obtain the required graphite negative electrode sheet.
Preparing a diaphragm: a PE porous polymer film with the thickness of 7-9 mm is used as a diaphragm.
Preparing a lithium ion battery: winding the prepared positive plate, the diaphragm and the prepared negative plate to obtain a naked battery cell without liquid injection; placing the bare cell in an outer package aluminum foil, injecting the prepared electrolyte into the dried bare cell, and performing vacuum packaging, standing, formation, shaping, sorting and other processes to obtain the required lithium ion battery, wherein the discharge voltage interval is set to be 3.0-4.5V.
Examples 2 to 10 and comparative examples 1 to 6
Examples 2 to 10 and comparative examples 1 to 6 were the same as example 1 except that the ratio of the additive to the electrolyte component was different. Specifically, the results are shown in Table 1.
TABLE 1
Figure BDA0003510289640000091
Figure BDA0003510289640000101
Figure BDA0003510289640000111
Test conditions
The lithium ion batteries prepared in examples 1 to 10 and comparative examples 1 to 6 were subjected to high temperature cycle and high temperature storage performance tests, respectively, according to the following test methods:
(1) high-temperature cycle test: and (3) placing the battery in an environment of 45 ℃, charging the formed battery to 4.5V by using a 1C constant current and constant voltage, stopping the current to be 0.02C, and then discharging to 3.0V by using a 1C constant current. After such charge/discharge cycles, the capacity retention rate after 600 weeks of cycling was calculated to evaluate the cycle performance thereof.
The calculation formula of the capacity retention rate after 600 cycles at 45 ℃ is as follows:
the 600 th cycle capacity retention (%) was (600 th cycle discharge capacity/first cycle discharge capacity) × 100%
(2) And (3) high-temperature storage test: the formed battery is charged to 4.5V by a 1C constant current and constant voltage at 25 ℃, the cut-off current is 0.02C, then the 1C constant current is discharged to 3.0V, the initial discharge capacity of the battery is measured, then the 1C constant current and constant voltage is charged to 4.5V, the cut-off current is 0.02C, the initial volume of the battery is measured, then the battery is stored for 14 days at 60 ℃, the thickness of the battery after being stored at 60 ℃ is measured, then the 1C constant current is discharged to 3.0V, the retention capacity of the battery is measured, then the 1C constant current and constant voltage is charged to 3.0V, the cut-off battery is 0.02C, then the 1C constant current is discharged to 3.0V, and the recovery capacity is measured.
The calculation formula of the capacity retention rate, the capacity recovery rate and the volume expansion is as follows:
battery capacity retention (%) — retention capacity/initial capacity 100%
Battery capacity recovery (%) -recovered capacity/initial capacity 100%
Cell volume expansion (%) (volume after 14 days-initial volume)/initial volume 100%.
Fig. 1 is a graph showing the test results of capacity retention rates of the batteries of examples 1-2 and comparative examples 1-2 after cycling at a high temperature of 45 ℃ for 600 weeks, and it can be seen from fig. 1 that the capacities of examples 1 and 2 show a tendency of gradual decay during cycling because double bonds are broken at the initial stage of the electrochemical reaction process in the formula (1), a dense solid electrolyte interfacial film can be formed on the positive and negative electrodes, and meanwhile, the formula (2) also opens the rings to participate in film formation, so that the ion density stability of the interfacial film is enhanced, and the overall performance of the battery can be kept stable for a long period of time; compared with the comparative examples 1 and 2, the structures of the formula (1) and the formula (2) are not added, so that the capacity shows the trend of diving during the circulation, the capacity retention rate of the examples 1 and 2 is more than 90% when the circulation is carried out for 600 weeks, the capacity retention rate of the comparative examples 1 and 2 can only be kept below 83%, and the value of recycling is not realized when the capacity of the lithium battery is reduced to be below 80% in the industry, so that the examples 1 and 2 can be reasonably speculated to be continuously circulated for a plurality of weeks after 600 weeks, the comparative example 1 directly meets the service life requirement of the lithium battery, and the comparative example 2 also meets the service life requirement in the next several weeks.
FIG. 2 is a graph showing the results of testing the capacity retention rate and recovery rate of the batteries of examples 1-2 and comparative examples 1-2 stored at a high temperature of 60 ℃ for 14 days; as can be seen from fig. 2, in examples 1 and 2, after 14 days of storage, the capacity retention rate is more than 90%, and the capacity recovery rate is more than 91%, so that the lithium battery can be stored for a while, because the-Si-O-bond can complex the metal ions dissolved out from the positive electrode under the high temperature environment, the catalytic reaction of the metal ions to the electrolyte is further reduced, and the Si atom is very easy to adsorb fluorine ions, thereby inhibiting the decomposition of the lithium salt; the B atom can be coordinated with an oxygen atom in the anode material, so that the crystal structure of the anode material in a high-temperature environment is stabilized, and the stability of the anode in the charging and discharging process is protected; the capacity retention rate and the recovery rate of the comparative examples 1 and 2 are below 68%, and the lithium battery reaches the rejection standard.
FIG. 3 is a graph showing the results of testing the volume increase rate of the batteries of examples 1-2 and comparative examples 1-2 after 14 days of high temperature storage at 60 ℃, and it can be seen from FIG. 3 that the volume expansion degree of examples 1 and 2 is small, and is only 4.4% and 3.5%, because the lithium battery pole piece surface formed a film stably after the structures of formula (1) and formula (2) are added, the positive electrode crystal structure is stable, and further the gas is not easily generated, and the permeability of lithium ion is strong, the lithium is not easily separated from the negative electrode surface to generate lithium dendrite, and the pole piece is not thickened; the lack of a stable environment inside the lithium batteries of comparative examples 1 and 2 resulted in the batteries swelling to 15.2% and 6.8%, which were significantly larger than the volume size of the examples.
The test results of the examples and comparative examples are summarized in table 2.
TABLE 2
Figure BDA0003510289640000131
As can be seen from the data in Table 2, the non-aqueous electrolyte containing the cyclic alkenylsiloxane and the cyclic boroxine compound in combination is adopted, and the high-voltage lithium ion battery prepared in the above embodiment is tested on high-temperature cycle and high-temperature storage performance, so that the capacity retention rate is up to 91% or more after being cycled for 600 times at 45 ℃, the capacity retention rate is up to 90% or more after being stored for 14 days at 60 ℃, the capacity recovery rate is up to 91% or more, and the volume expansion rate is as low as 4.8% or less. The lithium ion battery prepared by the electrolyte has the advantages of high long-cycle retention rate, high storage capacity retention rate and high recovery rate.
Furthermore, when the cyclic alkenyl siloxane and cyclic boroxine compound are used together with lithium difluorophosphate, vinyl sulfate, fluoroethylene carbonate, 1, 3-propane sultone, ethylene glycol dipropionitrile ether, 1,3, 6-hexanetricarbonitrile, succinonitrile, adiponitrile, lithium difluorobis (oxalato) phosphate and 1,1,2, 3-tetrafluoroethyl-2, 2,3, 3-tetrafluoropropyl ether, the combined use of the cyclic alkenyl siloxane and cyclic boroxine compound use shows more excellent battery performance, and the battery volume expansion rate after high-temperature storage is far smaller than a comparative example, therefore the electrolyte of the invention is applied to high-voltage lithium ion battery, have excellent high-temperature long cycle stability and high-temperature storage stability and good security performance.
Comparative examples 1 to 4 show that the capacity retention rate after cycling for 600 weeks at 45 ℃ is less than 83%, the capacity retention rate and the recovery rate after storing for 14 days at 60 ℃ at high temperature are both less than 70%, and the volume growth rate is much higher than that of the examples, which shows that when the electrolyte is not added with the cyclic alkenyl siloxane and the cyclic boroxine compound, the impedance of the high-voltage lithium battery is increased too much, the lithium ion conductivity is poor, the positive transition metal ions are dissolved out due to high temperature, the catalytic solvent is induced to be continuously decomposed, and the lithium ions are consumed excessively, so that the capacity retention rate and the recovery rate of the battery under high temperature are low. And because the solvent is continuously decomposed, on one hand, gas is generated, on the other hand, an SEI film is continuously repaired, the SEI film is continuously thickened, the pole piece is thickened, and the volume of the battery is increased in both aspects.
As can be seen from comparison of examples with comparative examples of comparative examples 5 to 6, the cyclic alkenylsiloxane compound having the structure represented by formula (1) and the cyclic boroxine compound having the structure represented by formula (2) act synergistically to give a battery having high capacity retention and recovery rates under high temperature conditions and a low volume expansion rate.
The applicant states that the present invention is described by the above examples for the lithium ion battery nonaqueous electrolyte and the lithium ion battery of the present invention, but the present invention is not limited to the above examples, that is, the present invention is not necessarily implemented by the above examples. It will be apparent to those skilled in the art that any modification of the present invention, equivalent substitutions of selected materials and additions of auxiliary components, selection of specific modes and the like, which are within the scope and disclosure of the present invention, are contemplated by the present invention.

Claims (10)

1. A lithium-ion battery nonaqueous electrolyte solution, characterized by comprising a lithium salt electrolyte, a nonaqueous solvent, and an additive, the additive comprising at least one cyclic alkenylsiloxane compound having a structure represented by formula (1) and at least one cyclic boroxine compound having a structure represented by formula (2):
Figure FDA0003510289630000011
wherein R is1Selected from hydrogen, halogen, cyano, substituted or unsubstituted C1-C5 alkyl, substituted or unsubstituted C6-C30 aryl, amido, phosphate ester, sulfonyl, siloxy or borate, and n is an integer of 3-10; r2Is selected from hydrogen, halogen, substituted or unsubstituted C1-C5 alkyl and substituted or unsubstituted C6-C30 aryl, and m is an integer of 3-10.
2. The nonaqueous electrolyte solution for lithium ion batteries according to claim 1, wherein when a group is a substituted group, the substituent is at least one selected from halogen, C1-C6 alkyl, and C1-C6 alkoxy.
3. The nonaqueous electrolytic solution for lithium-ion batteries according to claim 1 or 2, wherein the cyclic alkenylsiloxane compound having the structure represented by formula (1) is any one of 2,4,6, 8-tetramethyl-2, 4,6, 8-tetravinylcyclotetrasiloxane, 2,4,4,6,6,8, 8-octa (vinyl) -1,3,5,7,2,4,6, 8-tetraoxatetrasiloxane, tetramethyltetravinylcyclotetrasiloxane, or tetraethylenetetraphenylcyclotetrasiloxane;
preferably, the cyclic boroxine compound represented by formula (2) is any one of the following compounds:
Figure FDA0003510289630000021
4. the nonaqueous electrolyte solution for lithium ion batteries according to any one of claims 1 to 3, wherein the content of the cyclic alkenylsiloxane compound having a structure represented by formula (1) is 0.01 to 5% and the content of the cyclic borosiloxane compound having a structure represented by formula (2) is 0.01 to 5% based on 100% by mass of the total nonaqueous electrolyte solution for lithium ion batteries.
5. The nonaqueous electrolyte solution for a lithium ion battery according to any one of claims 1 to 4, wherein the additive further comprises other additives, the other additives comprising one or a combination of at least two of lithium difluorophosphate, vinyl sulfate, fluoroethylene carbonate, 1, 3-propane sultone, ethylene glycol dipropionitrile ether, 1,3, 6-hexanetrinitrile, succinonitrile, adiponitrile, lithium difluorobis (oxalato) phosphate, and 1,1,2, 3-tetrafluoroethyl-2, 2,3, 3-tetrafluoropropyl ether;
preferably, the content of the other additives is 0.01-25% of the total mass of the lithium ion battery nonaqueous electrolyte solution being 100%.
6. The nonaqueous electrolyte solution for a lithium ion battery according to any one of claims 1 to 5, wherein the lithium salt electrolyte comprises any one of or a combination of at least two of lithium hexafluorophosphate, lithium perchlorate, lithium trifluoromethanesulfonate, lithium bis-fluorosulfonylimide or lithium bis-trifluoromethanesulfonimide;
preferably, the content of the lithium salt electrolyte is 2-25% by taking the total mass of the lithium ion battery nonaqueous electrolyte as 100%.
7. The nonaqueous electrolyte solution for a lithium ion battery according to any one of claims 1 to 6, wherein the nonaqueous solvent is one of ethylene glycol diethyl ether, methyl propionate, methyl acetate, propyl propionate, methyl butyrate, ethyl butyrate, propyl acetate, butyl butyrate, acetonitrile, methyl propyl carbonate, ethyl propionate, γ -butyrolactone, sulfolane, dimethyl sulfoxide, tetrahydrofuran, propylene carbonate, ethyl acetate, diethyl carbonate, ethyl methyl carbonate, dimethyl carbonate, ethylene carbonate, or a combination of at least two thereof;
preferably, the content of the nonaqueous solvent is 40 to 92.98% based on 100% of the total mass of the nonaqueous electrolyte of the lithium ion battery.
8. A lithium ion battery comprising the lithium ion battery nonaqueous electrolyte solution according to any one of claims 1 to 7.
9. The lithium ion battery of claim 8, wherein the lithium ion battery comprises a battery case, a cell, and the lithium ion battery nonaqueous electrolyte of any one of claims 1 to 7, the cell and the lithium ion battery nonaqueous electrolyte being sealed within the battery case;
preferably, the cell includes a positive electrode, a negative electrode, and a separator or a solid electrolyte layer disposed between the positive electrode and the negative electrode.
10. The lithium ion battery according to claim 8 or 9, wherein the positive electrode comprises an active material capable of intercalating and deintercalating lithium, preferably a lithium transition metal composite oxide;
preferably, the anode includes a metal or alloy capable of inserting and extracting lithium or forming an alloy with lithium or a metal oxide capable of inserting/extracting lithium;
preferably, the active material capable of intercalating and deintercalating lithium is LiNixCoyMnzL(1-x-y-z)O2、LiCox'L(1-x')O2、LiNix”L'y'Mn(2-x”-y')O4、Liz'MPO4、LiMn2O4At least one of; wherein L is at least one of Al, Sr, Mg, Ti, Ca, Zr, Zn, Si and Fe; x is more than or equal to 0 and less than or equal to 1, y is more than or equal to 0 and less than or equal to 1, z is more than or equal to 0 and less than or equal to 1, x + y + z is more than 0 and less than or equal to 1, x ' is more than 0.3 and less than or equal to 0.6, y ' is more than or equal to 0.01 and less than or equal to 0.2, and L ' is at least one of Co, Al, Sr, Mg, Ti, Ca, Zr, Zn, Si or Fe; z' is more than or equal to 0.5 and less than or equal to 1, and M is at least one of Fe, Mn or Co;
preferably, the material of the negative electrode includes crystalline carbon, lithium metal, SiO2Graphite composite, SiC/graphite composite, LiMnO2、LiAl、Li3Sb、Li3Cd、LiZn、Li3Bi、Li4Si、Li4.4Pb、Li4.4Sn、LiC6、Li3FeN2、Li2.6CoN0.4、Li2.6CuN0.4Or Li4Ti5O12At least one of;
preferably, the charge cut-off voltage of the lithium ion battery is not less than 3.6V;
preferably, the working voltage of the lithium ion battery is 3.6V-5V, preferably 4.35V-4.8V.
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