CN115995609B - Electrolyte, preparation method thereof and lithium battery - Google Patents
Electrolyte, preparation method thereof and lithium batteryInfo
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- CN115995609B CN115995609B CN202211707115.5A CN202211707115A CN115995609B CN 115995609 B CN115995609 B CN 115995609B CN 202211707115 A CN202211707115 A CN 202211707115A CN 115995609 B CN115995609 B CN 115995609B
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Abstract
一种电解液及其制备方法和锂电池，属于能源技术领域。锂电池包括电解液、正极片、负极片以及隔膜。其中，电解液包括溶剂、锂盐和2‑(双(2‑氧基‑1,3‑二氧基‑4‑基)甲氧基)磷酰氧基丙烯基化合物添加剂。包含有该化合物添加剂的锂电池，在具有良好的阻燃性的同时，还能保持良好的电化学性能。An electrolyte, a preparation method thereof and a lithium battery belong to the field of energy technology. The lithium battery comprises an electrolyte, a positive electrode sheet, a negative electrode sheet and a separator. The electrolyte comprises a solvent, a lithium salt and a 2-(bis(2-oxy-1,3-dioxy-4-yl)methoxy)phosphoryloxypropylene compound additive. The lithium battery containing the compound additive has good flame retardancy and can maintain good electrochemical performance.
Description
Technical Field
The application relates to the technical field of secondary batteries, in particular to electrolyte, a preparation method thereof and a lithium battery.
Background
The commercial lithium battery has the advantages of high energy and power density, no memory effect, long cycle life, environmental friendliness and the like, and the application of the commercial lithium battery is rapidly expanding from the field of consumer electronics to the field of electric automobiles and new energy storage.
However, in recent years, with the large-scale popularization and application of lithium batteries, a large number of safety accidents related to the abuse of the lithium batteries occur every year worldwide, and research and improvement of the safety of the lithium batteries are continuously paid attention to and enhanced by academia and industry. The abuse conditions that cause thermal runaway (smoke, fire, explosion) are mainly mechanical abuse (e.g. extrusion, needling), electrical abuse (e.g. overcharging, internal short-circuiting), thermal abuse (e.g. thermal shock), etc., and the role of the electrolyte in the thermal runaway process of the lithium battery is critical.
Therefore, the development of the high-safety flame-retardant electrolyte is the most economical and simple strategy, and can effectively reduce the risk (probability) of thermal runaway combustion explosion of the lithium battery and greatly reduce the personnel and property damage caused by the thermal runaway.
Disclosure of Invention
Based on the defects, the application provides an electrolyte, a preparation method thereof and a lithium battery, so as to partially or completely solve the problem of thermal runaway of the lithium battery in the related art.
The application is realized in the following way:
In a first aspect, examples of the present application provide an electrolyte comprising a solvent, a lithium salt, and an additive comprising a 2- (bis (2-oxo-1, 3-dioxo-4-yl) methoxy) phosphoryloxypropenyl compound represented by formula (1):
Wherein R1 and R2 are each independently selected from one of a hydrogen atom, a fluorine substituted or unsubstituted C1-C6 chain alkyl group, a C3-C12 cycloalkyl group, a C2-C6 alkylene or alkynyl group, a C6-C12 cyclic alkylene group, a cyano group, a C1-C5 nitrile group, a methoxy group, an ethoxy group, a phenyl group, a benzene ring derivative group, and a five-membered or six-membered heterocyclic group.
In the implementation process, the 2- (bis (2-oxo-1, 3-dioxy-4-yl) methoxy) phosphoryloxypropenyl compound is added into the electrolyte, so that the lithium ion battery has a good flame retardant effect and negative electrode compatibility, and can improve the flame retardance of the lithium ion battery and reduce the negative influence of the additive on the electrochemical performance of the lithium ion battery. And the additive contains carbon-carbon double bonds, can polymerize at high temperature to form a high molecular compound, and is covered on the surfaces of the anode and the cathode of the lithium ion battery and the diaphragm, so that the interface impedance is increased, the transmission of lithium ions is blocked, the battery is broken, and further thermal runaway of the battery is prevented.
With reference to the first aspect, in an alternative embodiment of the present application, in the additive, R1 and R2 are each independently selected from a hydrogen atom, a C1-C6 chain alkyl group, a C3-C12 cycloalkyl group, a C2-C6 alkylene or alkynyl group, a C6-C12 cyclic alkylene group;
Optionally, in the additive, R1 and R2 are independently selected from hydrogen atoms, C1-C6 chain alkyl groups and C3-C12 cycloalkyl groups;
Optionally, in the additive, R1 and R2 are both selected from hydrogen atoms;
optionally, the additive accounts for 0.1% -20% of the total mass of the electrolyte.
In the implementation process, the additive accounts for 0.1% -20% of the total mass of the electrolyte, so that adverse effects of the additive on the electrochemical performance of the lithium battery can be reduced while the flame retardant effect is ensured.
With reference to the first aspect, in an alternative embodiment of the present application, the solvent is a carbonate, carboxylate or sulfate and fluoro-derivative solvents thereof;
optionally, the solvent is selected from at least one of ethylene carbonate, fluoroethylene carbonate, propylene carbonate, trifluoropropylene carbonate, gamma-butyrolactone, gamma-valerolactone, dimethyl carbonate, methylethyl carbonate, methyltrifluoroethyl carbonate, diethyl carbonate, (2, 2) -trifluoroethyl carbonate, ethyl acetate, ethyl difluoroacetate, propyl propionate, sultone, ethylene sulfite, propylene sulfite, methyl sulfide, diethyl sulfite, methyl formate, methyl acrylate and methyl butyrate.
With reference to the first aspect, in an alternative embodiment of the present application, the lithium salt is selected from at least one of lithium hexafluorophosphate, lithium perchlorate, lithium difluorophosphate, lithium tetrafluoroborate, lithium trifluoromethylsulfonate, lithium dioxaborate, lithium difluorooxalato borate, lithium hexafluoroaluminate, lithium bistrifluoromethylsulfonimide, lithium hexafluoroarsenate, and perfluoroalkyl sulfonyl methyl lithium;
optionally, the lithium salt accounts for 10-20% of the total mass of the electrolyte.
In an alternative embodiment of the application in combination with the first aspect, the electrolyte further comprises an auxiliary additive, wherein the auxiliary additive is at least one of 1, 3-propane sultone, 1, 4-butane sultone, propenyl-1, 3-sultone, vinyl sulfate, propylene sulfate, butylene sulfite, vinylene carbonate, fluoroethylene carbonate, lithium difluorosulfimide, lithium difluorooxalato borate, lithium difluorooxalato phosphate, lithium difluorophosphate and lithium tetrafluoroborate.
In the implementation process, the auxiliary additive is added to further improve the electrochemical performance of the lithium battery containing the electrolyte.
In a second aspect, embodiments of the present application provide a method of preparing an electrolyte, the method comprising mixing a solvent, a lithium salt, and an additive to prepare the electrolyte. The additive includes a 2- (bis (2-oxo-1, 3-dioxo-4-yl) methoxy) phosphoryloxypropenyl compound represented by formula (1):
the preparation method also comprises the preparation of the additive:
step A, obtaining an intermediate shown in a formula (2):
Step B, mixing the intermediate with the formula (3), and reacting the chlorine radical of the formula (2) with the hydroxyl of the formula (3) at the temperature of 23-27 ℃, wherein the formula (3) has the following structure:
Wherein R1 and R2 in the formula (1) are in one-to-one correspondence with R1 and R2 in the formula (3), and R1 and R2 are independently selected from one of a hydrogen atom, a fluorine substituted or unsubstituted C1-C6 chain alkyl group, a C3-C12 cycloalkyl group, a C2-C6 alkylene or alkyne group, a C6-C12 cyclic alkylene group, a cyano group, a C1-C5 nitrile group, a methoxy group, an ethoxy group, a phenyl group, a benzene ring derivative group and a five-membered or six-membered heterocyclic group.
According to the preparation method, the electrolyte containing the 2- (bis (2-oxo-1, 3-dioxy-4-yl) methoxy) phosphoryloxypropenyl compound additive can be prepared and obtained, has good flame retardant effect and lithium ion battery negative electrode compatibility, and can improve the flame retardance of the lithium ion battery and reduce the negative influence of the additive on the electrochemical performance of the lithium ion battery. And the additive contains a carbon-carbon double bond functional group, can polymerize at high temperature to form a high molecular compound, and is covered on the surfaces of the anode and the cathode of the lithium ion battery and the diaphragm, so that the interface impedance is increased, the transmission of lithium ions is blocked, the battery is broken, and further thermal runaway of the battery is prevented.
With reference to the second aspect, in an alternative embodiment of the present application, step a includes:
POCl 3 and 1, 2-glycerin carbonate are reacted at 0-3 ℃;
optionally, POCl 3, 1, 2-glycerin carbonate, chloroform and triethylamine react under the action of a 4-Dimethylaminopyridine (DMAP) catalyst at the temperature of 0-3 ℃;
in the step (B), the formula (3) is vinyl alcohol;
Optionally, reacting the intermediate, vinyl alcohol, chloroform and triethylamine under the action of a 4-Dimethylaminopyridine (DMAP) catalyst at a temperature of 23-27 ℃.
In the implementation process, POCl 3 is utilized to react with 1, 2-glycerin carbonate at 0-3 ℃ and under the action of a catalyst, an intermediate can be obtained, so that the intermediate is utilized to react with a compound shown in a formula (3) structure to prepare the 2- (bis (2-oxo-1, 3-dioxy-4-yl) methoxy) phosphoryloxypropenyl compound additive.
In a third aspect, an embodiment of the present application provides a lithium battery, including the electrolyte provided in the first aspect, a positive electrode sheet, a negative electrode sheet, and a separator.
In the implementation process, the lithium battery comprises the electrolyte provided by the first aspect, and the electrolyte has a good flame retardant effect and lithium ion battery negative electrode compatibility, so that the negative influence of the additive on the electrochemical performance of the lithium ion battery can be reduced while the flame retardance of the lithium ion battery is improved. And the additive in the electrolyte contains a carbon-carbon double bond functional group, can polymerize at high temperature to form a high molecular compound, and covers the surfaces of the positive plate, the negative plate and the diaphragm of the lithium ion battery, so that the interface impedance is increased, the transmission of lithium ions is blocked, the battery is broken, and further thermal runaway of the battery is prevented.
In combination with the third aspect, in an alternative embodiment of the present application, the positive electrode active material of the positive electrode sheet is selected from at least one of transition metal phosphate, transition metal oxide lithium salt, lithium titanate Li 4Ti5O12, transition metal sulfide.
With reference to the third aspect, in an alternative embodiment of the present application, the negative active material of the negative electrode sheet is selected from at least one of a carbon material, a silicon-tin alloy material, a silicon-carbon material, and a silicon oxygen material.
In the implementation process, the positive electrode active material and the negative electrode active material provided by the embodiment of the application can improve the compatibility of the positive electrode plate and the negative electrode plate with electrolyte and improve the electrochemical performance of the lithium battery.
Detailed Description
Embodiments of the present application will be described in detail below with reference to examples, but it will be understood by those skilled in the art that the following examples are only for illustrating the present application and should not be construed as limiting the scope of the present application. The specific conditions are not noted in the examples and are carried out according to conventional conditions or conditions recommended by the manufacturer. The reagents or apparatus used were conventional products commercially available without the manufacturer's attention.
The electrolyte and the lithium battery provided by the application are specifically described below:
Along with the large-scale popularization and application of the lithium battery, a large number of safety accidents related to the abuse thermal runaway of the lithium battery are easy to occur. Abusive conditions that cause thermal runaway (smoke, fire, explosion) are mainly mechanical abuse (e.g., extrusion, needling), electrical abuse (e.g., overcharging, internal shorting), and thermal abuse (e.g., thermal shock), among others.
At present, a plurality of safety improvement strategies for preventing the lithium battery from thermal runaway, ignition and explosion are adopted, such as flame-retardant electrolyte, flame-retardant heat-resistant shrinkage diaphragm, solid electrolyte, electrode materials with high structural stability (such as lithium iron phosphate (LFP)) and the like.
The electrolyte influences the thermal runaway of the lithium battery, and the development of the high-safety flame-retardant electrolyte is the most economical and simple strategy, so that the risk (probability) of combustion explosion of the thermal runaway of the lithium battery can be effectively reduced, and the personnel and property injuries caused by the thermal runaway are greatly reduced.
The inventors have attempted to improve the electrolyte by using a flame retardant phosphate compound (triethyl phosphate, trimethyl phosphate, dimethyl methyl phosphonate, etc.) and a phosphazene compound (ethoxy pentafluoroethylcyclotriphosphazene, hexafluorocyclotriphosphazene, etc.). The flame retardant is decomposed at high temperature and catalyzes the polymer to be attached to the surfaces of the anode material, the cathode material and the diaphragm, so that the internal circuit of the battery is broken, further thermal runaway is avoided, and meanwhile, the formed polymer can also play a role in isolating oxygen and combustible substances. PO-free radicals generated by the decomposition of the phosphorus flame retardant can capture H, HO and free radicals of inflammable gases such as O 2 released by the high temperature of the positive electrode material and the like generated by the high temperature decomposition of the electrolyte to form HPO, thereby preventing or slowing down the progress of combustion chain reaction and enhancing the flame retardant effect. And the flame retardant is decomposed at high temperature to generate flame retardant gases such as P, PO, HPO and the like, so that the concentration of the flame retardant gases is reduced, and the thermal runaway of the battery is delayed.
However, the inventors found that the addition of such compounds as phosphate and phosphazene to the electrolyte may cause incompatibility of the electrolyte with the graphite negative electrode, difficulty in forming a stable SEI film on the surface of the negative electrode, and co-intercalation with Li + to destroy the layered structure of the graphite.
Therefore, the inventors tried to reduce the compounds such as phosphate and phosphazene, but when the concentration of the flame retardant additive such as organic phosphate is too low (< 10%), there is little obvious flame retardant effect, and when the concentration is high (> 20%), the lithium intercalation performance of the graphite anode is significantly affected.
Accordingly, the inventors have provided a lithium battery to improve problems of low flame retardancy and poor electrochemical properties of the lithium battery.
The lithium battery comprises electrolyte, a positive plate, a negative plate and a diaphragm.
Wherein the electrolyte comprises a solvent, a lithium salt and an additive. Wherein the additive comprises a 2- (bis (2-oxo-1, 3-dioxo-4-yl) methoxy) phosphoryloxypropenyl compound represented by formula (1):
Wherein R1 and R2 are each independently selected from one of a hydrogen atom, a fluorine substituted or unsubstituted C1-C6 chain alkyl group, a C3-C12 cycloalkyl group, a C2-C6 alkylene or alkynyl group, a C6-C12 cyclic alkylene group, a cyano group, a C1-C5 nitrile group, a methoxy group, an ethoxy group, a phenyl group, a benzene ring derivative group, and a five-membered or six-membered heterocyclic group.
The electrolyte is added with the 2- (bis (2-oxo-1, 3-dioxy-4-yl) methoxy) phosphoryloxy propenyl compound, has good flame retardant effect and lithium ion battery negative electrode compatibility, can improve the flame retardance of the lithium ion battery and can reduce the negative influence of the additive on the electrochemical performance of the lithium ion battery. And the additive contains a carbon-carbon double bond functional group, can polymerize at high temperature to form a high molecular compound, and is covered on the surfaces of the anode and the cathode of the lithium ion battery and the diaphragm, so that the interface impedance is increased, the transmission of lithium ions is blocked, the battery is broken, and further thermal runaway of the battery is prevented.
The application is not limited to the specific type of R1 and R2, and by way of example, R1 is selected from H and R2 is selected from any one of C1-C6 chain alkyl groups.
In one possible embodiment, R1 and R2 are each independently selected from the group consisting of a hydrogen atom, a C1-C6 chain alkyl group, a C3-C12 cycloalkyl group, a C2-C6 alkylene or alkynyl group, a C6-C12 cyclic alkylene group. Illustratively, R1 is selected from hydrogen and R2 is selected from C6 chain alkyl. Illustratively, R1 is selected from C3 cycloalkyl groups and R2 is selected from C2 chain alkyl groups.
Illustratively, R1 and R2 are both selected from H. Further, the application also provides a preparation method of the additive, which comprises the following steps:
s1, obtaining an intermediate, wherein the intermediate is shown as a formula (2):
S2, mixing the intermediate with a compound shown in a formula (3), and reacting with a chloryl group shown in the formula (2) and a hydroxyl group shown in the formula (3) at a temperature of 23-27 ℃, wherein the structure of the formula (3) is as follows:
Wherein R1 and R2 in the formula (3) correspond to R1 and R2 in the formula (1), and R1 and R2 are each independently selected from one of a hydrogen atom, a fluorine-substituted or unsubstituted C1-C6 chain alkyl group, a C3-C12 cycloalkyl group, a C2-C6 alkylene or alkyne group, a C6-C12 cyclic alkylene group, a cyano group, a C1-C5 nitrile group, a methoxy group, an ethoxy group, a phenyl group, a benzene ring derivative group, and a five-membered or six-membered heterocyclic group.
Illustratively, R1 is selected from one of fluorine substituted C1-C6 chain alkyl groups and R2 is selected from one of C6-C12 cyclic alkylene groups. For example, R1 is selected from fluoro substituted C6 chain alkyl and R2 is selected from C6 cyclic alkylene.
Illustratively, R1 is selected from one of C1-C5 nitrile groups and R2 is selected from methoxy. Illustratively, R1 is selected from phenyl and R2 is selected from one of five-membered or six-membered heterocyclic groups. If R1 is selected from phenyl, R2 is selected from five-membered heterocyclic groups of benzene rings.
Further, the preparation method of the intermediate comprises the following steps:
POCl 3 and 1, 2-glycerin carbonate are reacted at 0-3 ℃.
Further, POCl 3, 1, 2-glycerin carbonate, chloroform, triethylamine and 4-Dimethylaminopyridine (DMAP) catalyst may be mixed and reacted at a temperature of 0 to 3 ℃ to obtain an intermediate.
Further, during the reaction, the reactants may be stirred.
By way of example, nitrogen bubbling may be employed. The exhaust gas generated during the nitrogen bubbling process was absorbed with NaOH solution.
Further, the stock solution after the reaction may be distilled to remove the substance and washed.
Illustratively, the washing may be performed with diethyl ether.
Illustratively, in step S2, methylene chloride, intermediates, vinyl alcohol, triethylamine and 4-Dimethylaminopyridine (DMAP) catalyst are placed in a reaction vessel, stirred and nitrogen is bubbled into the vessel until the atmosphere in the vessel is nitrogen, and the tail gas is absorbed with a 2mol/L NaOH solution. And (3) heating the reacted stock solution to 100 ℃, distilling under reduced pressure to remove impurities, washing and filtering the product with diethyl ether, and removing the washing solvent under reduced pressure at room temperature to obtain the additive.
Further, in the electrolyte, the additive accounts for 0.1% -20% of the total mass of the electrolyte.
Illustratively, the additive comprises a range between one or any two of 0.1%, 1%, 5%, 10% or 20% by weight of the electrolyte.
Further, the electrolyte also contains auxiliary additives.
The auxiliary additive is at least one selected from 1, 3-propane sultone, 1, 4-butane sultone, propenyl-1, 3-sultone, vinyl sulfate, propylene sulfate, butylene sulfite, vinylene carbonate, fluoroethylene carbonate, lithium bisfluorosulfonimide, lithium difluorooxalato borate, lithium difluorooxalato phosphate, lithium difluoroato phosphate and lithium tetrafluoro borate.
The application is not limited to a particular type of solvent, and in some possible embodiments, the solvent is a carbonate, carboxylate or sulfate and fluoro-derivative solvents thereof.
Illustratively, the solvent is selected from at least one of the solvents selected from the group consisting of ethylene carbonate, fluoroethylene carbonate, propylene carbonate, trifluoropropylene carbonate, gamma-butyrolactone, gamma-valerolactone, dimethyl carbonate, methylethyl carbonate, methyltrifluoroethyl carbonate, diethyl carbonate, (2, 2) -trifluoroethyl carbonate, ethyl acetate, ethyl difluoroacetate, propyl propionate, sultone, ethylene sulfite, propylene sulfite, methyl sulfide, diethyl sulfite, methyl formate, methyl acrylate, and methyl butyrate.
The present application is not limited to a particular type of lithium salt, and in some possible embodiments, the lithium salt is selected from at least one of lithium hexafluorophosphate, lithium perchlorate, lithium difluorophosphate, lithium tetrafluoroborate, lithium trifluoromethanesulfonate, lithium dioxalate borate, lithium difluorooxalato borate, lithium hexafluoroaluminate, lithium bistrifluoromethylsulfonimide, lithium hexafluoroarsenate, and perfluoroalkyl sulfonyl methyl lithium.
Further, the lithium salt accounts for 10-20% of the total mass of the electrolyte.
Illustratively, the lithium salt comprises a range between any one or both of 10%, 11%, 15%, 18% or 20% of the total mass of the electrolyte.
Further, the application is not limited to the particular type of positive electrode active material in the positive electrode sheet, and in one possible embodiment, the positive electrode active material is one or more combinations of transition metal phosphates, transition metal oxide lithium salts, lithium titanate Li 4Ti5O12, transition metal sulfides.
Further, the material for preparing the positive plate also comprises an adhesive and a conductive agent.
The preparation method of the positive plate comprises a coating method.
The preparation method of the positive electrode comprises the steps of mixing a high-nickel ternary material, conductive carbon black and a binder polyvinylidene fluoride according to the mass ratio of 96.8:2.0:1.2, dispersing the mixture in N-methyl-2-pyrrolidone to obtain positive electrode slurry, uniformly coating the positive electrode slurry on two sides of an aluminum foil, drying, calendaring and vacuum drying, and welding an aluminum positive electrode lug by an ultrasonic welder to obtain a positive electrode sheet with the thickness of 100-150 mu m.
Further, the present application is not limited to a specific type of negative electrode active material in the negative electrode sheet, and in one possible embodiment, the negative electrode active material of the negative electrode sheet is at least one of a carbon material, a silicon-tin alloy material, a silicon-carbon material, and a silicon oxygen material.
The preparation method of the negative electrode comprises the following steps of mixing graphite, conductive carbon black, binder styrene-butadiene rubber and carboxymethyl cellulose according to the mass ratio of 95:1.5:1.5:2, dispersing the mixture in deionized water to obtain negative electrode slurry, coating the negative electrode slurry on two sides of a copper foil, drying, calendaring and vacuum drying, and welding a nickel negative electrode lug by an ultrasonic welder to obtain a negative electrode sheet with the thickness of 150-250 mu m.
Further, the application is not limited to a particular type of separator, and in some possible embodiments, the separator includes a porous polymer membrane, a nonwoven fabric separator, and an inorganic composite membrane.
Further, the preparation method of the lithium ion battery also comprises battery assembly. The battery cell is obtained by winding a positive plate, a negative plate and a PE ceramic diaphragm, and is packaged by an aluminum plastic film, dried, injected with electrolyte for sealing, and then subjected to the procedures of standing, formation, secondary sealing, capacity division and the like.
The electrolyte and the lithium battery according to the present application are described in further detail below with reference to examples.
Example 1
The embodiment 1 of the application provides a lithium battery, which comprises electrolyte, a positive plate, a negative plate and a diaphragm, and is prepared by the following method:
(1) Preparation of electrolyte
Mixing Ethylene Carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (EMC) in a weight ratio of 1:1:1 to obtain a mixed solvent, adding 0.5% of additive (2- (bis (2-oxo-1, 3-dioxy-4-yl) methoxy) phosphoryloxypropenyl compound), 0.5% of Vinylene Carbonate (VC), 1% of fluoroethylene carbonate (FEC), 1% of 1, 3-Propane Sultone (PS) to obtain battery electrolyte, and lithium salt LiPF 6 mol/L. The specific components of the electrolyte are shown in table 1.
(2) Preparation of positive plate
Mixing a high-nickel ternary material, conductive carbon black and a binder polyvinylidene fluoride according to the mass ratio of 96.8:2.0:1.2, dispersing the mixture in N-methyl-2-pyrrolidone to obtain positive electrode slurry, uniformly coating the positive electrode slurry on two sides of an aluminum foil, drying, calendaring and vacuum drying, and welding an aluminum positive electrode lug by an ultrasonic welder to obtain a positive electrode sheet with the thickness of 100-150 mu m. Wherein the positive electrode active material is purchased from high nickel ternary materials of Zhen Zhenhua or Shenzhen Bei Terui.
(3) Preparation of negative electrode sheet
Mixing graphite, conductive carbon black, binder styrene-butadiene rubber and carboxymethyl cellulose according to the mass ratio of 95:1.5:1.5:2, and dispersing in deionized water to obtain the negative electrode slurry. And coating the negative electrode slurry on two sides of a copper foil, drying, calendaring and vacuum drying, and welding a nickel negative electrode lug by an ultrasonic welding machine to obtain a negative electrode sheet with the thickness of 150-250 mu m.
Wherein the negative electrode active material is purchased from artificial graphite of Shenzhen Bei Terui.
(4) Battery assembly
The high-nickel ternary lithium battery is assembled through winding the positive plate, the negative plate and the PE ceramic diaphragm to obtain a battery core, packaging the battery core in an aluminum plastic film, drying, injecting electrolyte for sealing, and performing the procedures of standing, formation, secondary sealing, capacity division and the like to obtain the lithium ion battery.
Wherein, the diaphragm is purchased from star source material, and PE coated ceramic diaphragm with the thickness of 20 mu m.
Example 2
Example 2 of the present application provides a lithium battery, which is different from example 1 in that:
In the electrolyte, the addition amount of the additive (2- (bis (2-oxo-1, 3-dioxo-4-yl) methoxy) phosphoryloxypropenyl compound) was adjusted to 1%, the solvent ratio was reduced, (EC: EMC: dec=1:1:1) and the ratio of the additive (2- (bis (2-oxo-1, 3-dioxo-4-yl) methoxy) phosphoryloxypropenyl compound) was adjusted to 99:1, and the other reagents and lithium salt were kept unchanged. The specific components of the electrolyte are shown in table 1.
Example 3
Embodiment 3 of the present application provides a lithium battery, wherein the electrolyte differs from embodiment 1 in that:
the addition amount of the additive (2- (bis (2-oxo-1, 3-dioxo-4-yl) methoxy) phosphoryloxypropenyl compound) was adjusted to 3%, the solvent ratio was reduced, (EC: dec=1:1:1) ratio to the additive (2- (bis (2-oxo-1, 3-dioxo-4-yl) methoxy) phosphoryloxypropenyl compound) was adjusted to 97:3, and the other reagents and lithium salt remained unchanged. The specific components of the electrolyte are shown in table 1.
Example 4
Example 4 of the present application provides a lithium battery, and the electrolyte differs from example 1 in that:
The addition amount of the additive (2- (bis (2-oxo-1, 3-dioxo-4-yl) methoxy) phosphoryloxypropenyl compound) was adjusted to 5%, the solvent ratio was reduced, (EC: dec=1:1:1) to the ratio of the additive (2- (bis (2-oxo-1, 3-dioxo-4-yl) methoxy) phosphoryloxypropenyl compound) was adjusted to 95:5, and the other reagents and lithium salt remained unchanged. The specific components of the electrolyte are shown in table 1.
Example 5
Example 5 of the present application provides a lithium battery, and the electrolyte differs from example 1 in that:
The addition amount of the additive (2- (bis (2-oxo-1, 3-dioxo-4-yl) methoxy) phosphoryloxypropenyl compound) was adjusted to 10%, the solvent ratio was reduced, (EC: dec=1:1:1) ratio to the additive (2- (bis (2-oxo-1, 3-dioxo-4-yl) methoxy) phosphoryloxypropenyl compound) was adjusted to 90:10, and the other reagents and lithium salt remained unchanged. The specific components of the electrolyte are shown in table 1.
Example 6
Example 6 of the present application provides a lithium battery, and the electrolyte differs from example 1 in that:
The addition amount of the additive (2- (bis (2-oxo-1, 3-dioxo-4-yl) methoxy) phosphoryloxypropenyl compound) was adjusted to 15%. The solvent ratio was adjusted (EC: EMC: dec=1:1:1) to additive (2- (bis (2-oxo-1, 3-dioxo-4-yl) methoxy) phosphoryloxypropenyl compound) ratio was adjusted to 85:15, the other reagents and lithium salts remained unchanged. The specific components of the electrolyte are shown in table 1.
Example 7
Embodiment 7 of the present application provides a lithium battery, wherein the electrolyte differs from embodiment 1 in that:
The addition amount of the additive (2- (bis (2-oxo-1, 3-dioxo-4-yl) methoxy) phosphoryloxypropenyl compound) was adjusted to 20%. The ratio of solvent ratio (EC: EMC: dec=1:1:1) to additive (2- (bis (2-oxo-1, 3-dioxo-4-yl) methoxy) phosphoryloxypropenyl compound) was adjusted to 80:20, the other reagents and lithium salts remained unchanged. The specific components of the electrolyte are shown in table 1.
Example 8
Example 8 of the present application provides a lithium battery, and the electrolyte differs from example 5 only in that:
The mixed solvent was adjusted to ec:dec: FEMC (chinese name of FEMC is methyltrifluoroethyl carbonate) =1:1:1, the others remaining unchanged. The specific components of the electrolyte are shown in table 1.
Example 9
The embodiment of the application provides a lithium battery, and electrolyte differs from embodiment 5 only in that:
The mixed solvent was adjusted to EC: dec=1:2, the others remained unchanged. The specific components of the electrolyte are shown in table 1.
Comparative example 1
Comparative example 1 of the present application provides a lithium battery, and the electrolyte is different from example 1 in that:
The electrolyte solvent is EC: EMC: DEC=1:1:1, no compound additive is added, and the rest is kept unchanged. The specific components of the electrolyte are shown in table 1.
Comparative example 2
Comparative example 2 of the present application provides a lithium battery, and the electrolyte is different from example 1 in that:
The electrolyte solvent is EC: EMC: dec=1:1:1, 10% of triethyl phosphate is added, and the others remain unchanged. The specific components are shown in Table 1.
Comparative example 3
Comparative example 3 of the present application provides a lithium battery, the electrolyte differs from example 1 in that:
the electrolyte solvent is EC: EMC: DEC=1:1:1, 10% of pentafluoroethoxyphosphazene is added, and the others are kept unchanged. The specific components of the electrolyte are shown in table 1.
TABLE 1
Test example 1 cycle performance test of lithium ion battery
The lithium ion batteries of examples 1 to 9 and comparative examples 1 to 3 were first charged to a voltage of 4.V at a constant current of 1C, charged to a current of 0.05C at a constant voltage, and then discharged to 2.75V at a constant current of 1C at 25C and 45C, respectively, and subjected to 500-cycle charge-discharge tests, and the discharge capacity at 500-th cycle was detected. The test results are shown in Table 2.
Wherein, the capacity retention= (500 th discharge capacity/first discharge capacity) ×100%.
Test example 2 electrolyte self-extinguishing time test
Taking a piece of PP or PE diaphragm with the length of 20cm and the width of 40cm, soaking the diaphragm into an electrolyte sample for 5min, taking out the diaphragm soaked with the electrolyte by using tweezers, igniting the diaphragm soaked with the electrolyte by using an igniter, and recording the combustion condition of the diaphragm soaked with the electrolyte and the time from combustion to automatic extinction. The test results are shown in Table 2.
TABLE 2
The result analysis shows that the lithium battery provided by the application has the advantages of quick self-extinguishing time or incombustibility of the electrolyte and good flame retardance. Meanwhile, the electrolyte provided by the application can also enable the lithium battery to keep higher cycle stability.
The above description is only of the preferred embodiments of the present application and is not intended to limit the present application, but various modifications and variations can be made to the present application by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the protection scope of the present application.
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| WO2011034067A1 (en) * | 2009-09-15 | 2011-03-24 | 宇部興産株式会社 | Nonaqueous electrolyte solution and electrochemical element using same |
| WO2012105404A1 (en) * | 2011-01-31 | 2012-08-09 | 三菱化学株式会社 | Non-aqueous electrolytic solution, and non-aqueous electrolyte secondary battery using same |
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| CN109524715B (en) * | 2018-11-22 | 2021-09-17 | 桑顿新能源科技(长沙)有限公司 | Additive for lithium ion battery electrolyte, electrolyte and lithium ion battery |
| CN113675474B (en) * | 2021-08-23 | 2023-02-03 | 广州天赐高新材料股份有限公司 | A new phosphorus-containing high-safety electrolyte and lithium-ion battery |
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| WO2012105404A1 (en) * | 2011-01-31 | 2012-08-09 | 三菱化学株式会社 | Non-aqueous electrolytic solution, and non-aqueous electrolyte secondary battery using same |
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