CN114824469A - Electrolyte containing high-voltage high-temperature additive composition and lithium ion battery - Google Patents
Electrolyte containing high-voltage high-temperature additive composition and lithium ion battery Download PDFInfo
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- H—ELECTRICITY
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- 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
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- H01M10/05—Accumulators with non-aqueous electrolyte
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Abstract
The invention discloses an electrolyte of a high-voltage high-temperature additive composition, which comprises a main lithium salt, an organic solvent and an additive, wherein the additive comprises: the first additive is selected from the structure shown in the formula (I-1) and/or the formula (I-2), and the second additive is selected from at least one of the structures shown in the formula (II-1), (II-2) or (II-3), wherein the structural formula of the additive is shown in the specification. The electrolyte provided by the invention is used for a high-voltage battery system, has excellent high-temperature cycle performance and high-temperature storage performance, has lower internal resistance of a battery core, and can inhibit moisture and acidity in the electrolyte.
Description
Technical Field
The invention relates to the field of lithium ion battery electrolyte, in particular to electrolyte capable of improving high-temperature cycle performance and high-temperature storage performance of a high-voltage lithium ion battery and reducing internal resistance of a battery core and the lithium ion battery.
Background
High voltage batteries for high energy density systems are a development trend for lithium batteries, but with the increase of energy density, the electrochemical performance of the battery cell, especially high temperature storage and high temperature cycling, faces a great challenge. In order to improve the high-temperature performance of the battery, high-temperature additives such as sulfonate compounds such as 1, 3-Propane Sultone (PS) and propenyl-1, 3-sultone (PES), acid anhydride compounds, or nitrile compounds are often added. However, the sulfonate compound is a sulfur-containing additive, so that the problems of environmental protection and thermal stability exist; the high-temperature storage performance of the anhydride compound is insufficient, and the defect of accelerated attenuation can occur in the later cycle period of the battery; although nitrile compounds have obvious advantages in the aspect of high-temperature storage of battery cells, interface films are too thick, the internal resistance of the battery is high, and the nitrile compounds are incompatible with graphite negative electrodes.
The patent KR1020170110995A of LG company discloses a combined additive combining unsaturated silane and lithium bis (fluorosulfonyl) imide (LiFSI), which can improve the cycle performance and high-temperature storage stability of a battery cell, but the unsaturated silane can form a high-resistance interfacial film on the surfaces of a positive electrode and a negative electrode to cause lithium deposition; the deposited Li in turn reacts with the electrolyte, consuming active lithium resulting in capacity loss. In addition, when the voltage is more than 3.5V, LiFSI can corrode an Al current collector, so that the lithium iron phosphate anode material is not suitable for ternary high-voltage anode materials.
The Ningde time patent CN109309248A discloses a combined additive combining phosphate compounds and sulfate compounds/sulfonate compounds, which can inhibit the high-temperature storage gas generation of a battery, improve the retention rate of high-temperature storage residual capacity and further improve the high-temperature storage performance, but also has the defect of high internal resistance.
The existing additives such as vinyl sulfate (DTD) or Methylene Methanedisulfonate (MMDS) are beneficial to improving the high-temperature performance of the battery core and reducing the internal resistance, but under a high-voltage system, the electrolyte can continuously generate oxidative decomposition reaction on the surface of the positive electrode, so that the high-temperature (above 45 ℃) storage performance and thermal shock performance of the battery are deteriorated, and the improvement effect is still not ideal.
Therefore, it is very practical to find a low-resistance high-temperature additive or additive composition in a high-voltage battery system.
Disclosure of Invention
In order to solve the technical problems, the invention provides the electrolyte containing the high-voltage high-temperature additive composition, which can obviously improve the high-temperature cycle performance and the high-temperature storage performance of the battery and has low cell internal resistance.
The purpose of the invention is realized by the following technical scheme:
an electrolyte containing a high voltage, high temperature additive composition comprising a primary lithium salt, an organic solvent, the electrolyte further comprising:
a first additive selected from the group consisting of structures represented by the following formula (I-1) and/or formula (I-2):
wherein R is 1 、R 2 、R 3 Independently selected from C1-C5 alkyl, C1-C5 haloalkyl, C1-C5A cyano-substituted hydrocarbyl group, a C2-C5 unsaturated hydrocarbyl group, or a C2-C5 halogenated unsaturated hydrocarbyl group;
a second additive selected from at least one of the structures represented by the following formulas (II-1), (II-2) or (II-3):
the formula (II-1) represents a chain structure, wherein A is selected from silicon, boron, nitrogen or phosphorus, L is selected from oxygen or a direct bond, and R is 4 、R 5 、R 6 、R 7 Independently selected from C1-C5 alkyl, C1-C5 haloalkyl, C2-C5 unsaturated hydrocarbyl, C2-C5 halogenated unsaturated hydrocarbyl or C1-C5 cyano substituted hydrocarbyl; a. b, c, d are 0 or 1, and at least two of them are 1, meaning that there are at least two branches attached to A; the formula (II-1) contains at least two unsaturated bonds;
the formulas (II-2) and (II-3) represent a multi-membered heterocyclic ring, wherein X 1 Is boron or nitrogen, Q is selected from carbonyl or oxygen; n represents the number of repeating units on the multi-element heterocyclic ring, and n is selected from 2-6; r 8 Selected from C2-C5 unsaturated alkyl, C2-C5 halogenated unsaturated alkyl or C1-C5 cyano substituted alkyl; r 9 、R 10 Independently selected from C1-C5 alkyl, C1-C5 haloalkyl, C2-C5 unsaturated hydrocarbyl, C2-C5 halogenated unsaturated hydrocarbyl or C1-C5 cyano substituted hydrocarbyl, and R is independently selected from 9 、R 10 At least one of which contains an unsaturated bond. R 8 、R 9 、R 10 The unsaturated bond is any one of carbon-carbon double bond, carbon-carbon triple bond or carbon-nitrogen triple bond.
Preferably, R 1 、R 2 、R 3 Independently selected from C1-C3 alkyl, C1-C3 haloalkyl, C1-C3 cyano-substituted hydrocarbyl, C2-C3 unsaturated hydrocarbyl or C2-C3 halogenated unsaturated hydrocarbyl;
in the formula (II-1), R 4 、R 5 、R 6 、R 7 Independently selected from C1-C3 alkyl, C1-C3 haloalkyl, C2-C3 unsaturated hydrocarbyl, C2-C3 halogenated unsaturated hydrocarbyl or C1-C3 cyano substituted hydrocarbyl; a. at least three of b, c and d are 1;
formula (II-2),In the (II-3), n is selected from 3-5; r 8 Selected from C2-C3 unsaturated alkyl, C2-C3 halogenated unsaturated alkyl or C1-C3 cyano substituted alkyl; r 9 、R 10 Independently selected from C1-C3 alkyl, C1-C3 halogenated alkyl, C2-C3 unsaturated alkyl, C2-C3 halogenated unsaturated alkyl or C1-C3 cyano substituted alkyl.
More preferably, R 1 、R 2 、R 3 Independently selected from methyl, ethyl, cyano, methylenecyano, monofluoromethyl, trifluoroethyl, allyl;
in the formula (II-1), R 4 、R 5 、R 6 、R 7 Independently selected from the group consisting of ethenyl, propenyl, perfluoroethenyl, methylenecyano;
in the formulae (II-2) and (II-3), R 8 Selected from the group consisting of vinyl, propenyl; r 9 、R 10 Independently selected from methyl and vinyl.
Most preferably, in the electrolyte containing the high-voltage high-temperature additive composition according to the present invention, the first additive is selected from at least one of the following structures:
the second additive is selected from at least one of the following structures:
in the electrolyte containing the high-voltage high-temperature additive composition, the addition amount of the first additive in the electrolyte is 0.1-5.0%, and the addition amount of the second additive in the electrolyte is 0.1-5.0%. Preferably, the first additive is added in the electrolyte in an amount of 0.2 to 2%, and the second additive is added in the electrolyte in an amount of 0.2 to 3%.
First addition of the inventionWhen the additive and the second additive are used together, the first additive can be oxidized on the surface of the positive electrode in advance to form a compact CEI film; the second additive can form a film on the surfaces of the positive electrode and the negative electrode at the same time, and further prevent the continuous decomposition of the electrolyte on the surface of the electrode. Since the mechanism of action is not clear, the present inventors have speculated through studies that: the P-F bond in the first additive is unstable and easy to fall off, and F - The strong electron-withdrawing ability of the composite material forms active sites on the surfaces of the positive and negative electrode materials, and the second additive is favorable for better film formation, so that the internal resistance of the battery is obviously reduced, the gas generation of the battery core is further inhibited, and the high-temperature cycle and high-temperature storage performance of the battery core are improved. Meanwhile, the first additive also has the effects of removing acid and water, and Koeun Kim and the like think that reducing the content of water and acidity in the electrolyte is beneficial to inhibiting the decomposition of LiPF6, reducing the consumption of active lithium and the deterioration of an SEI film and reducing the internal resistance of the battery.
In the electrolyte containing the high-voltage high-temperature additive composition, the main lithium salt is the common lithium salt in the electrolyte. Preferably, the main lithium salt is at least one selected from lithium hexafluorophosphate, lithium tetrafluoroborate, lithium bis (oxalato) borate, lithium difluoro (oxalato) phosphate, lithium tetrafluorooxalato phosphate, lithium bis (fluorosulfonyl) imide and lithium bis (trifluoromethylsulfonyl) imide, and the concentration of the main lithium salt in the electrolyte is 0.3-3M. More preferably, the lithium salt includes lithium hexafluorophosphate, and the concentration of the lithium salt in the electrolyte is 0.5-2M.
In the electrolyte containing the high-voltage high-temperature additive composition, the organic solvent is only organic solvent commonly used in the electrolyte. Preferably, the organic solvent is at least one selected from the group consisting of a carbonate or fluorocarbonate compound having C3 to C6, a carboxylate or fluorocarboxylate compound having C3 to C8, a sulfone compound, and an ether compound.
More preferably, the carbonate or fluorocarbonate compound having 3-6 carbon atoms is at least one selected from the group consisting of ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, fluoroethylene carbonate and difluoroethylene carbonate;
the carboxylic ester or fluorinated carboxylic ester compound of C3-C8 is at least one selected from gamma-butyrolactone, methyl acetate, methyl propionate, methyl butyrate, ethyl acetate, ethyl propionate, ethyl butyrate, propyl acetate, propyl propionate and fluorinated ethyl acetate;
the sulfone compound is at least one selected from sulfolane, dimethyl sulfoxide, dimethyl sulfone and diethyl sulfone;
the ether compound is at least one selected from diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether and 1, 1, 2, 2-tetrafluoroethyl-2, 2, 3, 3-tetrafluoropropyl ether.
The electrolyte containing the high-voltage high-temperature additive composition further comprises a basic additive, wherein the basic additive is selected from at least one of an anhydride compound, a sulfonate compound, a sulfate compound, a trimethylsilyl compound, an unsaturated cyclic carbonate compound or a fluorinated cyclic carbonate compound, and the dosage of the basic additive accounts for 0.1-10% of the total mass of the electrolyte.
Wherein the acid anhydride compound is selected from at least one of succinic anhydride, maleic anhydride and citraconic anhydride; the sulfonate compound is at least one selected from 1, 3-propane sultone, 1, 4-butane sultone, methylene methanedisulfonate and 1, 3-propylene sultone; the sulfate compound is at least one selected from vinyl sulfate, trimethylene cyclic sulfate, vinyl methyl sulfate and 4, 4' -divinyl sulfate; the trimethylsilyl ester compound is selected from at least one of tris (trimethylsilyl) borate, tris (trimethylsilyl) phosphate, tris (trimethylsilyl) phosphite and tris (trimethylsilyl) trifluoromethanesulfonate; the unsaturated cyclic carbonate compound is selected from vinylene carbonate and/or vinyl ethylene carbonate; the fluorinated cyclic carbonate compound is selected from at least one of fluoroethylene carbonate, difluoroethylene carbonate and trifluoromethyl ethylene carbonate.
The invention also provides a lithium ion battery which comprises a positive electrode, a negative electrode, a diaphragm and the electrolyte containing the high-voltage high-temperature additive composition.
The active material of the positive electrode is selected from a nickel-cobalt-manganese ternary material, a nickel-cobalt-aluminum ternary material, a lithium cobaltate material or a lithium iron phosphate material.
The active material of the negative electrode is selected from graphite, silicon carbon, silicon monoxide, silicon, tin, metallic lithium or composite materials thereof.
The charge cut-off voltage of the lithium ion battery is higher than 4.2V. The electrolyte is particularly suitable for high-voltage and high-temperature battery systems.
Compared with the prior art, the invention has the beneficial effects that:
1. when the electrolyte is used for a high-voltage battery system, the high-temperature cycle performance and the high-temperature storage performance of the battery can be improved, and the electrolyte has lower internal resistance of a battery core.
2. The electrolyte can inhibit the moisture and acidity in the electrolyte, further reduce the resistance of the battery and improve the performance of the battery.
Detailed Description
The present invention is further illustrated by the following examples, which are not intended to limit the invention to these embodiments. It will be appreciated by those skilled in the art that the present invention encompasses all alternatives, modifications and equivalents as may be included within the scope of the claims.
Preparation of electrolyte
Preparing a basic electrolyte: in an argon-filled glove box (moisture < 5ppm, oxygen < 10ppm), Ethylene Carbonate (EC), Ethyl Methyl Carbonate (EMC), diethyl carbonate (DEC) were mixed in the mass ratio EC: EMC: DEC ═ 3:5:2 was mixed homogeneously and lithium hexafluorophosphate (LiPF) was added slowly to the mixed solution 6 ) To LiPF 6 The molar concentration of (a) was 1.0mol/L, and a base electrolyte was obtained.
Example 1: to the base electrolyte, 1.0 wt% of compound a1 and 5.0 wt% of compound B1 were added to obtain an electrolyte of the present example.
Example 2: to the base electrolyte, 0.5 wt% of compound a3 and 2.0 wt% of compound B2 were added to obtain an electrolyte of the present example.
Example 3: to the base electrolyte, 2.0 wt% of compound a5 and 1.0 wt% of compound B3 were added to obtain an electrolyte of the present example.
Example 4: to the base electrolyte, 5.0 wt% of compound a7 and 0.2 wt% of compound B4 were added to obtain an electrolyte of the present example.
Example 5: to the base electrolyte, 1.0 wt% of compound a2 and 0.5 wt% of compound B5 were added to obtain an electrolyte of the present example.
Example 6: to the base electrolyte, 0.2 wt% of compound a4 and 0.2 wt% of compound B6 were added to obtain an electrolyte of the present example.
Example 7: to the base electrolyte, 2.0 wt% of compound a6 and 2.0 wt% of compound B7 were added to obtain an electrolyte of the present example.
Example 8: to the base electrolyte, 5.0 wt% of compound a1 and 0.5 wt% of compound B8 were added to obtain an electrolyte of the present example.
Example 9: to the base electrolyte, 0.5 wt% of compound a1 and 0.2 wt% of compound B3 were added to obtain an electrolyte of the present example.
Example 10: to the base electrolyte, 0.5 wt% of compound a1 and 0.2 wt% of compound B6 were added to obtain an electrolyte of the present example.
Example 11: to the base electrolyte, 0.5 wt% of compound a1 and 0.2 wt% of compound B9 were added to obtain an electrolyte of the present example.
Example 12: to the base electrolyte, 0.5 wt% of compound a3 and 0.2 wt% of compound B3 were added to obtain an electrolyte of the present example.
Example 13: to the base electrolyte, 0.5 wt% of compound a7 and 0.2 wt% of compound B3 were added to obtain an electrolyte of the present example.
Comparative example 1: to the base electrolyte, 0.5 wt% of compound a1 was added to obtain an electrolyte of this comparative example.
Comparative example 2: to the base electrolyte, 1.0 wt% of compound a2 was added to obtain an electrolyte of this comparative example.
Comparative example 3: to the base electrolyte, 0.2 wt% of compound B3 was added to obtain an electrolyte of this comparative example.
Comparative example 4: to the base electrolyte, 0.5 wt% of compound B5 was added to obtain an electrolyte of this comparative example.
Comparative example 5: to the base electrolyte, 0.5 wt% of compound a1 and 0.2 wt% of Adiponitrile (ADN) were added to obtain an electrolyte of this comparative example.
Comparative example 6: to the base electrolyte, 0.5 wt% of compound a3 and 0.2 wt% of 1, 3-Propane Sultone (PS) were added to obtain an electrolyte of this comparative example.
Comparative example 7: to the base electrolyte, 0.5 wt% of the compound Methylene Methanedisulfonate (MMDS) and 0.2 wt% of B3 were added to obtain an electrolyte of this comparative example.
Comparative example 8: to the base electrolyte, 0.5 wt% of a compound of vinyl sulfate (DTD) and 0.2 wt% of B6 were added to obtain an electrolyte of this comparative example.
Comparative example 9: to the base electrolyte, 0.5 wt% of compound a1 and 0.2 wt% of Vinylene Carbonate (VC) were added to obtain an electrolyte of this comparative example.
Comparative example 10: to the base electrolyte, 0.2 wt% of compound B3 and 0.5 wt% of Vinylene Carbonate (VC) were added to obtain an electrolyte of this comparative example.
Secondly, manufacturing and performance testing of the battery
The lithium ion battery electrolytes of the embodiment and the comparative example are respectively manufactured into lithium ion power batteries with the soft package capacity of 1000mAh, each lithium ion power battery comprises a positive pole piece, a negative pole piece, a diaphragm, an electrolyte and a battery auxiliary material, and the positive active material is LiNi 0.83 Co 0.07 Mn 0.2 O 2 The negative active material is graphite.
The preparation process comprises the following steps: winding the positive pole piece, the diaphragm and the negative pole piece together into a roll core, sealing by using an aluminum plastic film, baking to enable the electrode moisture to meet the requirement, injecting electrolyte into the baked battery cell, and performing standing, formation, capacity grading and aging processes to obtain the finished soft package battery cell.
The lithium ion battery is tested for various performances, and the method comprises the following steps:
1. high temperature cycle performance test
Charging at 45 ℃ with a constant current of 1C to a charge cut-off voltage, then charging at a constant voltage until the current drops to 0.1C, then discharging at a constant current of 1C to 2.8V, cycling for a specific number of cycles, recording the discharge capacity of the 1 st cycle and the discharge capacity of the last 1 th cycle, and calculating the capacity retention rate of the battery cycle according to the following formula:
capacity retention rate is 100% of the last 1 week discharge capacity/1 week discharge capacity.
2. High temperature storage Performance test
And (3) cycling for 1 week at room temperature according to a cycling performance test method, recording the discharge capacity, the internal resistance and the volume of the 1 st week, then carrying out constant current charging at a current of 1C until the charge cut-off voltage is reached, carrying out constant voltage charging until the current is reduced to 0.1C, standing in a constant-temperature oven at the temperature of 60 ℃ for 28 days, then cycling for 2 weeks at room temperature according to the cycling performance test method, and recording the discharge capacity, the discharge capacity at the 2 nd week, the internal resistance and the volume after storage after standing at high temperature. The capacity retention rate, internal resistance increase rate and volume expansion rate after battery storage were calculated as follows:
capacity retention rate (discharge capacity at 1 week after high-temperature standing/discharge capacity at 1 week × 100%.
The increase rate of internal resistance (internal resistance after storage-internal resistance at 1 st week)/internal resistance at first week 100%.
Volume expansion rate (volume after storage-volume at 1 st week)/volume at first week 100%.
3. Internal resistance of battery cell
0.2C constant current charging is carried out to adjust the SOC of the battery cell to 50 percent, the battery cell is placed for 30min, and the open-circuit voltage OCV after the placement is tested 1 . Then discharging for 10s according to the maximum pulse current (3C) specified by the battery manufacturer, and collecting the voltage OCV at the moment of termination of large-current discharge 2 . Cell DCIR was calculated as follows:
DCIR＝(OCV 1 -OCV 2 )/3C
4. water content and acidity
Testing the moisture and acidity of the electrolyte before and after 24 hours of storage at 50 ℃: performed as SJ/T11723-2018, the free acid content, calculated as HF, is calculated according to the following formula:
C HF ＝C*V*M HF *1000/m
in the formula:
C HF free acid content (in HF), mg/kg;
c is the concentration of sodium methoxide standard titration solution, mol/L;
v is the volume of the sodium methoxide standard titration solution consumed by titration, mL;
m is sample mass, g;
M HF the molar mass of hydrofluoric acid (20.006), g/mol.
The arithmetic mean of the two test values was taken as the test result.
The specific test results are shown in the following tables 1-2:
TABLE 1 NCM622-4.3V electrochemical test results
The test results of comparative examples 1 to 8 and comparative examples 1 to 4 show that the combination of the first additive and the second additive improves the high-temperature cycle performance of the battery cell compared with the single use of the first additive. Compared with the single use of the second additive, the defect of high internal resistance is overcome. More importantly, the retention rate of the high-temperature circulating capacity of the electrolyte after combination is further improved, the gas generation of the battery cell after 28 days of high-temperature storage is greatly reduced, the increase of internal resistance is delayed, and the high-temperature storage performance of the battery cell is improved.
The test results of the comparative examples 9 to 13 and the comparative examples 5 to 10 show that the effect of the combination of the first additive and the second additive is higher than the high-temperature cycle capacity retention rate of the first additive and other high-temperature additives, and the volume expansion rate of the mixture after storage is smaller. The combination of the first additive and the second additive of the present invention has a lower internal resistance than the combination of the second additive with other additives having a lower internal resistance. Therefore, the scheme of combining the first additive and the second additive not only greatly improves the high-temperature storage and cycle performance of the battery cell, but also has lower internal resistance in a high-voltage system.
TABLE 2 moisture and acidity test results after 24h storage of electrolyte at 45 deg.C
As can be seen from table 2, the first type of additive has the functions of removing acid and water, and can suppress the increase of moisture and acidity after the electrolyte is stored, thereby improving the thermal stability of the electrolyte.
Claims (11)
1. An electrolyte containing a high-voltage high-temperature additive composition, which comprises a main lithium salt and an organic solvent, and is characterized in that: the electrolyte further includes:
a first additive selected from the group consisting of structures represented by the following formula (I-1) and/or formula (I-2):
wherein R is 1 、R 2 、R 3 Independently selected from C1-C5 alkyl, C1-C5 haloalkyl, C1-C5 cyano-substituted hydrocarbyl, C2-C5 unsaturated hydrocarbyl or C2-C5 halogenated unsaturated hydrocarbyl;
a second additive selected from at least one of the structures represented by the following formulas (II-1), (II-2) or (II-3):
in the formula (II-1), A is selected from silicon, boron, nitrogen or phosphorus, L is selected from oxygen or a direct bond, R 4 、R 5 、R 6 、R 7 Independently selected from C1-C5 alkyl, C1-C5 haloalkyl, C2-C5 unsaturated hydrocarbon group, C2-C5 halogenated unsaturated hydrocarbon group orC1-C5 cyano-substituted hydrocarbyl; a. b, c, d are 0 or 1, and at least two of them are 1; the formula (II-1) contains at least two unsaturated bonds;
the formulas (II-2) and (II-3) represent a multi-membered heterocyclic ring, wherein X 1 Is boron or nitrogen, Q is selected from carbonyl or oxygen; n represents the number of repeating units on the multi-element heterocyclic ring, and n is selected from 2-6; r 8 Selected from C2-C5 unsaturated alkyl, C2-C5 halogenated unsaturated alkyl or C1-C5 cyano substituted alkyl; r 9 、R 10 Independently selected from C1-C5 alkyl, C1-C5 haloalkyl, C2-C5 unsaturated hydrocarbyl, C2-C5 halogenated unsaturated hydrocarbyl or C1-C5 cyano substituted hydrocarbyl, and R is independently selected from 9 、R 10 At least one of which contains an unsaturated bond.
2. The electrolyte containing the high voltage, high temperature additive composition of claim 1, wherein:
R 1 、R 2 、R 3 independently selected from C1-C3 alkyl, C1-C3 haloalkyl, C1-C3 cyano-substituted hydrocarbyl, C2-C3 unsaturated hydrocarbyl or C2-C3 halogenated unsaturated hydrocarbyl;
in the formula (II-1), R 4 、R 5 、R 6 、R 7 Independently selected from C1-C3 alkyl, C1-C3 haloalkyl, C2-C3 unsaturated hydrocarbyl, C2-C3 halogenated unsaturated hydrocarbyl or C1-C3 cyano substituted hydrocarbyl; a. at least three of b, c and d are 1;
in the formulas (II-2) and (II-3), n is selected from 3-5; r 8 Selected from C2-C3 unsaturated alkyl, C2-C3 halogenated unsaturated alkyl or C1-C3 cyano substituted alkyl; r 9 、R 10 Independently selected from C1-C3 alkyl, C1-C3 halogenated alkyl, C2-C3 unsaturated alkyl, C2-C3 halogenated unsaturated alkyl or C1-C3 cyano substituted alkyl.
3. The electrolyte containing the high voltage, high temperature additive composition of claim 2, wherein:
R 1 、R 2 、R 3 independently selected from methyl, ethyl, cyano, methylenecyano, monofluoromethyl, trifluoroethyl, allyl;
in the formula (II-1), R 4 、R 5 、R 6 、R 7 Independently selected from the group consisting of ethenyl, propenyl, perfluoroethenyl, methylenecyano;
in the formulae (II-2) and (II-3), R 8 Selected from the group consisting of vinyl, propenyl; r 9 、R 10 Independently selected from methyl and vinyl.
4. The electrolyte containing the high voltage, high temperature additive composition of claim 3, wherein: the first additive is selected from at least one of the following structures:
the second additive is selected from at least one of the following structures:
5. the electrolyte containing the high voltage, high temperature additive composition according to any of claims 1 to 4, wherein: the addition amount of the first additive in the electrolyte is 0.1-5.0%, and the addition amount of the second additive in the electrolyte is 0.1-5.0%.
6. The electrolyte solution containing the high voltage, high temperature additive composition according to claim 1, wherein: the main lithium salt is selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium bis (oxalato) borate, lithium difluoro (oxalato) phosphate, lithium tetrafluorooxalato phosphate, lithium bis (fluorosulfonyl) imide and lithium bis (trifluoromethylsulfonyl) imide, and the concentration of the main lithium salt in the electrolyte is 0.5-3M;
the organic solvent is at least one of carbonate or fluoro carbonate compounds of C3-C6, carboxylic ester or fluoro carboxylic ester compounds of C3-C8, sulfone compounds and ether compounds.
7. The electrolyte containing the high voltage, high temperature additive composition of claim 6, wherein:
the carbonate or fluoro carbonate compound of C3-C6 is at least one selected from ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, fluoro ethylene carbonate and difluoro ethylene carbonate;
the carboxylic ester or fluorinated carboxylic ester compound of C3-C8 is at least one selected from gamma-butyrolactone, methyl acetate, methyl propionate, methyl butyrate, ethyl acetate, ethyl propionate, ethyl butyrate, propyl acetate, propyl propionate and fluorinated ethyl acetate;
the sulfone compound is at least one selected from sulfolane, dimethyl sulfoxide, dimethyl sulfone and diethyl sulfone;
the ether compound is at least one selected from diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether and 1, 1, 2, 2-tetrafluoroethyl-2, 2, 3, 3-tetrafluoropropyl ether.
8. The electrolyte containing the high voltage, high temperature additive composition according to any of claims 1 to 7, wherein: the electrolyte also comprises a basic additive, wherein the basic additive is at least one of an anhydride compound, a sulfonate compound, a sulfate compound, a trimethylsilyl ester compound, an unsaturated cyclic carbonate compound or a fluorinated cyclic carbonate compound, and the using amount of the basic additive accounts for 0.1-20% of the total mass of the electrolyte.
9. The electrolyte solution containing the high voltage, high temperature additive composition according to claim 8, wherein:
the acid anhydride compound is at least one selected from succinic anhydride, maleic anhydride and citraconic anhydride;
the sulfonate compound is at least one selected from 1, 3-propane sultone, 1, 4-butane sultone, methylene methanedisulfonate and 1, 3-propylene sultone;
the sulfate compound is at least one selected from vinyl sulfate, trimethylene cyclic sulfate, vinyl methyl sulfate and 4, 4' -divinyl sulfate;
the trimethylsilyl ester compound is selected from at least one of tris (trimethylsilyl) borate, tris (trimethylsilyl) phosphate, tris (trimethylsilyl) phosphite and tris (trimethylsilyl) trifluoromethanesulfonate;
the unsaturated cyclic carbonate compound is selected from vinylene carbonate and/or vinyl ethylene carbonate; the fluorinated cyclic carbonate compound is selected from at least one of fluoroethylene carbonate, difluoroethylene carbonate and trifluoromethyl ethylene carbonate.
10. A lithium ion battery comprises a positive electrode, a negative electrode and a diaphragm, and is characterized in that: the lithium ion battery further comprises the lithium ion battery electrolyte of any of claims 1-9.
11. The lithium ion battery of claim 10, wherein: the charge cut-off voltage of the lithium ion battery is higher than 4.2V.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN116960467A (en) * | 2023-09-15 | 2023-10-27 | 宁德时代新能源科技股份有限公司 | Battery cell, battery and electricity utilization device |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116960467A (en) * | 2023-09-15 | 2023-10-27 | 宁德时代新能源科技股份有限公司 | Battery cell, battery and electricity utilization device |
| CN116960467B (en) * | 2023-09-15 | 2024-02-20 | 宁德时代新能源科技股份有限公司 | Battery cell, battery and electricity utilization device |
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