CN110635167B - Nonaqueous electrolyte solution, battery containing same, and electric vehicle - Google Patents
Nonaqueous electrolyte solution, battery containing same, and electric vehicle Download PDFInfo
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- CN110635167B CN110635167B CN201810648865.7A CN201810648865A CN110635167B CN 110635167 B CN110635167 B CN 110635167B CN 201810648865 A CN201810648865 A CN 201810648865A CN 110635167 B CN110635167 B CN 110635167B
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
- H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
- H01M10/0566—Liquid materials
- H01M10/0567—Liquid materials characterised by the additives
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/058—Construction or manufacture
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M2220/00—Batteries for particular applications
- H01M2220/20—Batteries in motive systems, e.g. vehicle, ship, plane
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
- Y02P70/50—Manufacturing or production processes characterised by the final manufactured product
Abstract
The invention discloses a non-aqueous electrolyte, a battery containing the non-aqueous electrolyte and an electric vehicle, wherein the non-aqueous electrolyte comprises a lithium salt, an organic solvent and an additive, the additive comprises fluorobenzenesulfonate and a nitrogen-containing heterocyclic dinitrile compound, when the additive is added into the electrolyte, the electrolyte is applied to the battery, and the additive and the electrolyte form a stable oxidation-resistant network structure containing LiPF6, fluorobenzenesulfonate and the nitrogen-containing heterocyclic dinitrile as a protective layer on the surface of a positive electrode together under the synergistic action, so that the further side reaction between the electrolyte and the positive electrode material is prevented, and the stability and the safety performance of the battery are greatly improved.
Description
Technical Field
The present invention relates to the field of nonaqueous electrolytic solutions, and specifically relates to a nonaqueous electrolytic solution, a battery containing the same, and an electric vehicle.
Background
At the present stage, the development of electric vehicle industrialization puts higher requirements on the safety, energy density and cycle life of the power battery, and the safety problem faced by higher and higher energy density is more and more severe. The battery can generate heat in the operation process, the traditional carbonate electrolyte and a high-voltage positive electrode material can generate side reaction to further release heat, when the heat cannot be timely dissipated, a series of side reaction can be caused, the temperature of the battery is rapidly increased, and finally the thermal runaway of the battery is caused.
In order to solve the above-mentioned existing technical problems, related patents disclose that using a high flash point solvent such as a fluoro solvent, a sulfone solvent, a cyclic carboxylic ester, etc. or adding a phosphate flame retardant additive such as trimethyl phosphate, triphenyl phosphate, etc. to an electrolyte can improve the safety performance of the electrolyte, but there are various problems: the high-flash-point solvent fluoro solvent, the sulfone solvent, the cyclic carboxylic ester and the phosphoric acid flame-retardant additive can affect the film formation on the surface of the negative electrode, and further affect the cycle performance of the battery, in addition, the phosphate flame-retardant additive can generate a violent exothermic reaction with the lithium-intercalated graphite, and the battery can generate thermal runaway in advance when the temperature is higher than 130 ℃.
Meanwhile, the prior art (JP 2009093839A) discloses that benzene sulfonate additives are separately added into an electrolyte, and the additives can form an SEI film on the surface of a positive electrode, so that further reaction between the electrolyte and the positive electrode material is prevented, and the safety performance of a battery is improved.
In addition, the prior art (application No. CN 201010560842.4) discloses that an aromatic nitrile compound having two or more nitrogen atoms, which is a phenyl group or a nitrogen-containing heterocyclic ring, is added to an electrolyte, and this additive decomposes on the surface of a negative electrode to form a protective film, thereby inhibiting the decomposition of a solvent, whereby the initial discharge efficiency of a battery can be improved. However, the compatibility of the additives with lithium salt LiPF6 is poor, on one hand, the antioxidant effect of lithium salt LiPF6 can be weakened by adding the additives, and on the other hand, the solubility of lithium salt LiPF6 can be lowered, so that the cycle performance and rate performance of the battery are greatly influenced.
Disclosure of Invention
In order to solve the above problems, the present application provides a nonaqueous electrolytic solution comprising a lithium salt, an organic solvent, and an additive, wherein the additive comprises a fluorobenzenesulfonate having a structural formula shown in formula (I):
formula (I)
Wherein R is selected from one of alkyl with 1-6 carbon atoms, halogenated alkyl with 1-6 carbon atoms, alkenyl with 2-6 carbon atoms, alkynyl with 2-6 carbon atoms, aryl and halogenated aryl; r1、R2、R3And R4Each independently selected from H, Cl, F, Br, I, alkyl with 1-6 carbon atoms, halogenated alkyl with 1-6 carbon atoms, alkenyl with 2-6 carbon atoms and alkynyl with 2-6 carbon atoms, and R1、R2、R3And R4At least one of which is F;
the structural formula of the nitrogen-containing heterocyclic dinitrile compound is shown as the formula (II):
(ii) a In the formula, R5Is a five-membered heterocyclic ring containing nitrogen or a six-membered heterocyclic ring containing nitrogen.
Preferably, the fluorobenzene sulfonate comprises one or more of methyl 2-fluorobenzene sulfonate, methyl 3-fluorobenzene sulfonate, methyl 4-fluorobenzene sulfonate, methyl 2, 4-difluorobenzene sulfonate, methyl 2, 5-difluorobenzene sulfonate, methyl 2, 6-difluorobenzene sulfonate, methyl 3, 4-difluorobenzene sulfonate, methyl 3, 5-difluorobenzene sulfonate and methyl 2,3, 4-trifluorobenzene sulfonate.
Preferably, the fluorobenzene sulfonate comprises one or more of methyl 2-fluorobenzene sulfonate, methyl 3-fluorobenzene sulfonate, methyl 2, 4-difluorobenzene sulfonate, methyl 2, 5-difluorobenzene sulfonate and methyl 2, 6-difluorobenzene sulfonate.
Preferably, the nitrogen-containing heterocyclic dinitrile compound comprises one or more of 2, 3-dicyanopyrazine, 2, 3-dicyanopyridine, 2, 4-dicyanopyridine, and 6-cyano-2- (4-cyanobenzene) indole.
Preferably, the nitrogen-containing heterocyclic dinitrile compound comprises one or more of 2, 3-dicyanopyrazine and 6-cyano-2- (4-cyanobenzene) indole.
Preferably, the content of the fluorobenzenesulfonate is 2 to 10wt% based on the total mass of the nonaqueous electrolytic solution.
Preferably, the content of the nitrogen-containing heterocyclic dinitrile compound is 2 to 10wt% based on the total mass of the nonaqueous electrolytic solution.
Preferably, the mass ratio of the fluorobenzenesulfonate to the nitrogen-containing heterocyclic dinitrile compound is 0.2:1 to 5: 1.
Preferably, the nonaqueous electrolyte further contains an auxiliary additive, wherein the auxiliary additive comprises one or more of 1, 3-propane sultone, 1, 4-butane sultone, propenyl-1, 3-sultone, vinyl sulfate, propylene sulfate, butylene sulfite, vinylene carbonate, fluoroethylene carbonate, bis (oxalato) borate and bis (fluorosulfonyl) imide lithium.
Preferably, the content of the auxiliary additive is 0.05 wt% to 20 wt% based on the total mass of the nonaqueous electrolytic solution.
Preferably, the organic solvent is selected from one or more of dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, propyl methyl carbonate, dipropyl carbonate, ethylene carbonate, propylene carbonate, vinylene carbonate, gamma-butyrolactone, sultone, ethylene sulfite, propylene sulfite, methyl sulfide, diethyl sulfite, methyl formate, methyl acrylate, methyl butyrate and ethyl acetate.
Preferably, the lithium salt is selected from LiBOB and LiPF6、LiBF4、LiSbF6、LiClO4、LiCF3SO3、Li(CF3SO2)2N、LiC4F9SO3、LiAlO4、LiAsF6、LiAlCl4One or more of LiCl, LiI and low-fatty acid lithium carbonate, wherein the concentration of the lithium salt is 0.3-3 mol/L.
In a second aspect of the present disclosure, a battery is provided, which includes a battery case, and a battery cell and a nonaqueous electrolyte solution sealed in the battery case, wherein the battery cell includes a positive electrode, a negative electrode, and a separator, and the nonaqueous electrolyte solution is the above-mentioned provided nonaqueous electrolyte solution.
A third object of the present application is to provide an electric vehicle, which contains the battery described above.
The inventor of the application discovers in experiments that when the fluoro-benzenesulfonate and the nitrogen-containing heterocyclic dinitrile compound are added into the electrolyte at the same time and then the electrolyte is applied to the battery, the stability and the safety performance of the prepared battery are greatly improved, and the inventor discovers through further exploration that the two additives can be well adsorbed on the surface of the positive electrode and form a stable protective film along with the increase of voltage; in addition, the fluorinated benzene sulfonate can improve the compatibility between lithium salt LiPF6 and the nitrogen-containing heterocyclic dinitrile compound, the nitrogen-containing heterocyclic dinitrile compound can also improve the stability of the fluorinated benzene sulfonate at high temperature, and the fluorinated benzene sulfonate and the nitrogen-containing heterocyclic dinitrile compound have a synergistic effect to form a stable antioxidant network structure containing LiPF6, the fluorinated benzene sulfonate and the nitrogen-containing heterocyclic dinitrile on the surface of the positive electrode as a protective layer, so that further side reaction between electrolyte and a positive electrode material is prevented, and the stability and the safety performance of the battery are greatly improved.
Detailed Description
The traditional carbonate electrolyte and electrode materials generate side reactions on a solid-liquid interface to release heat, when the heat cannot be timely dissipated, a series of side reactions can be caused, the temperature of the battery is rapidly increased, and finally the thermal runaway of the battery is caused. In the prior art, various film-forming additives are added into the electrolyte, so that side reactions between the electrolyte and electrode materials are prevented to some extent, but the comprehensive performance of the battery is influenced to a greater or lesser extent.
The present application addresses the above-mentioned problems and provides a nonaqueous electrolytic solution comprising a lithium salt, an organic solvent, and an additive including a fluorobenzenesulfonate having a structural formula shown in formula (I):
formula (I)
Wherein R is selected from alkyl with 1-6 carbon atoms, halogenated alkyl with 1-6 carbon atoms, alkenyl with 2-6 carbon atoms, alkynyl with 2-6 carbon atoms, aryl and halogenated aryl; r1, R2, R3 and R4 are independently selected from H, Cl, F, Br, I, alkyl with 1-6 carbon atoms, halogenated alkyl with 1-6 carbon atoms, alkenyl with 2-6 carbon atoms and alkynyl with 2-6 carbon atoms, wherein at least one of R1, R2, R3 and R4 is F;
the structural formula of the nitrogen-containing heterocyclic dinitrile compound is shown as the formula (II):
(ii) a In the formula, R is a five-membered heterocycle or a six-membered heterocycle containing nitrogen.
The alkyl group having 1 to 6 carbon atoms in R in the formula (I) may be a linear, branched or cyclic alkyl group, and the present application is not limited thereto, and specific examples thereof include a methyl group, an ethyl group, a n-propyl group, an isopropyl group, a n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a n-pentyl group, a neopentyl group, a sec-pentyl group, a tert-pentyl group, a n-hexyl group, and a 2-hexyl group. The haloalkyl group having 1 to 6 carbon atoms may be a straight chain or a branched chain, and the present application is not limited thereto, and examples thereof include a substituent in which at least one of hydrogen atoms contained in the alkyl group is substituted with a halogen atom including F, Cl, Br, and I, and specific examples thereof include a trifluoromethyl group, a 2-fluoroethyl group, a 3-fluoro-n-propyl group, a 2-fluoroisopropyl group, a 4-fluoro-n-butyl group, a 3-fluoro-sec-butyl group, a 5-fluoro-n-pentyl group, and a 4-fluoro-isopentyl group, and in the specific examples, F may be substituted with Cl, B, or I.
In the structural formula (I), R is an alkenyl group having 2 to 6 carbon atoms, and specific examples thereof include a vinyl group, a propenyl group, an allyl group, and a butenyl group.
In the structural formula (I), R is an alkynyl group having 2 to 6 carbon atoms, and specific examples thereof include an ethynyl group, a propargyl group, and a propynyl group.
In the structural formula (I), R is an aromatic group, and the aromatic group comprises phenyl, biphenyl, alkyl phenyl, halogenated phenyl and the like.
In the structural formula (I), R1, R2, R3 and R4 may be different or at least two of them are the same, the application is not limited, at least one of R1, R2, R3 and R4 is F, other groups may be selected from one or more of H, Cl, F, Br, I, C1-6 alkyl, C1-6 haloalkyl, C2-6 alkenyl and C2-6 alkynyl, when R1, R2, R3 and R4 are selected from C1-6 alkyl, C1-6 haloalkyl, C2-6 alkenyl and C2-6 alkynyl, the above detailed explanation is followed, and details are not repeated herein.
Specific examples of R1, R2, R3 and R4 in the sulfonate represented by structural formula (I) include: r1= F, R2= R3= R4= H, the fluorobenzenesulfonate is 2-fluorobenzenesulfonate; r1= R4= F, R2= R3= H, the fluorobenzenesulfonate is 2, 4-fluorobenzenesulfonate; and when R1= R2= R3= R4= F, the fluorobenzenesulfonate is 2,3,4, 5-fluorobenzenesulfonate or the like.
Preferable examples of the fluorobenzenesulfonate compound represented by the structural formula (I) include methyl 2-fluorobenzenesulfonate, methyl 3-fluorobenzenesulfonate, methyl 4-fluorobenzenesulfonate, methyl 2, 4-difluorobenzenesulfonate, methyl 2, 5-difluorobenzenesulfonate, methyl 2, 6-difluorobenzenesulfonate, methyl 3, 4-difluorobenzenesulfonate, methyl 3, 5-difluorobenzenesulfonate and methyl 2,3, 4-trifluorobenzenesulfonate when R is methyl.
Further preferably, the fluorobenzene sulfonate comprises one or more of methyl 2-fluorobenzene sulfonate, methyl 3-fluorobenzene sulfonate, methyl 2, 4-difluorobenzene sulfonate, methyl 2, 5-difluorobenzene sulfonate and methyl 2, 6-difluorobenzene sulfonate. In experiments, technicians of the invention find that when the fluorinated benzene sulfonate is added into the electrolyte and the electrolyte is used for a battery, an antioxidant network formed on the surface of a positive electrode by the additive is more stable, and the safety of the battery is greatly improved.
When R is ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, neopentyl, sec-pentyl, tert-pentyl, n-hexyl, 2-hexyl or the like, the corresponding fluorobenzenesulfonate compound can be preferably used as described above.
The above compounds can be synthesized commercially or by themselves, and the present application is not limited thereto.
As the five-membered heterocycle containing nitrogen as R in the structural formula (II), pyrrolidine, pyrrole, pyrazole, imidazole, 3-pyrroline, 2-pyrroline, 1,2, 3-triazole and 1,2, 4-triazole are exemplified.
As the nitrogen-containing six-membered heterocyclic ring as R in the structural formula (II), piperidine, pyridine, pyrazine, morpholine, pyrimidine, piperazine, 1,2, 4-triazine and 1,3, 5-triazine are exemplified.
Preferable examples of the nitrogen-containing heterocyclic compound represented by the structural formula (II) include 2, 3-dicyanopyrazine, 2, 3-dicyanopyridine, 2, 4-dicyanopyridine, 2, 3-dicyanoindole, and 6-cyano-2- (4-cyanobenzene) indole.
Further preferably, the nitrogen-containing heterocyclic dinitrile compound comprises one or more of 2, 3-dicyanopyrazine and 6-cyano-2- (4-cyanobenzene) indole. The technical personnel of the invention accidentally find out in experiments that when the nitrogenous heterocyclic dinitrile compound is added into the electrolyte and the electrolyte is applied to the battery, the antioxidant network formed on the surface of the positive electrode by the additive is more stable, and the safety of the battery is greatly improved.
The above compounds can be synthesized commercially or by themselves, and the present application is not limited thereto.
The application the additive have higher oxidation resistance, the flash point is high, nonflammable, all contain asymmetric strong electron-withdrawing group for the electron cloud of whole molecule is partial to one end, and whole molecule one end has the negative charge, along with the voltage rising the oxidation-resistant additive can be adsorbed to the positive pole surface, especially the lone pair electron on the nitrogen atom for nitrogenous aromatic ring dinitrile compound is adsorbed to the positive pole surface more easily, has greatly suppressed the chemical reaction between high voltage positive pole and carbonate solvent. However, the nitrogen-containing heterocyclic dinitrile compound is incompatible with the lithium salt LiPF6, and when such a compound is added alone in the electrolyte, the following two effects occur: (a) LiPF6 is itself oxidation resistant and the addition of aromatic dinitrile additives reduces the antioxidant effect of LiPF 6. (b) After a certain amount of nitrogen-containing aromatic ring dinitrile solvent is added, the solubility of LiPF6 is low, and the cycle performance and rate performance of the battery are greatly influenced.
In addition, when the fluorinated benzene sulfonate is added into the electrolyte, a carbonate solvent is oxidized by a high-voltage positive electrode to generate water at high temperature, the water reacts with LiPF6 to generate acid, the fluorinated benzene sulfonate is subjected to acidolysis to generate phenol and sulfonic acid, the two substances and a lithium-embedded negative electrode generate violent exothermic reaction, and the safety performance of the battery is greatly influenced.
The inventor of the present application discovered in experiments that, when the two additives are added into the electrolyte at the same time, the technical problems can be solved well, and the safety performance and the stability performance of the battery can be greatly improved.
According to the nonaqueous electrolyte provided by the invention, the content of the fluorobenzenesulfonate is 2-10 wt% based on the total mass of the nonaqueous electrolyte; the inventor of the application finds that the safety performance of the battery can be well improved and the performance of the battery cannot be greatly influenced when the fluorinated benzene sulfonate with the content is added into the electrolyte through a plurality of experiments.
According to the non-aqueous electrolyte provided by the invention, the content of the nitrogen-containing heterocyclic dinitrile is 2-10 wt% based on the total mass of the non-aqueous electrolyte; the inventor of the application finds that when the nitrogen-containing heterocyclic dinitrile with the content is added into the electrolyte, the safety performance of the battery can be well improved, and the performance of the battery cannot be greatly influenced.
Preferably, the mass ratio of the fluorobenzenesulfonate to the nitrogen-containing heterocyclic dinitrile compound is 0.2:1 to 5:1, and a great deal of experiments show that when the content range of the fluorobenzenesulfonate and the nitrogen-containing heterocyclic dinitrile compound is in the range and the proportion ratio of the fluorobenzenesulfonate and the nitrogen-containing heterocyclic dinitrile compound is in the range, the fluorobenzenesulfonate can well improve the compatibility between the lithium salt LiPF6 and the nitrogen-containing heterocyclic dinitrile compound, and meanwhile, the nitrogen-containing heterocyclic dinitrile compound can also well improve the stability of the fluorobenzenesulfonate at high temperature, and the synergistic effect of the fluorobenzenesulfonate and the nitrogen-containing heterocyclic dinitrile compound is optimal, so that the safety performance of the battery.
According to the nonaqueous electrolytic solution, preferably, the nonaqueous electrolytic solution further contains an auxiliary additive, the auxiliary additive comprises at least one of 1,3 propane sultone, 1,4 butane sultone, propenyl-1, 3-sultone, ethylene sulfate, propylene sulfate, butylene sulfite, vinylene carbonate, fluoroethylene carbonate, bis (oxalato) boric acid and bis (fluorosulfonyl) imide lithium, and the auxiliary additive and the additive disclosed by the invention are applied to the electrolytic solution together, so that the stability of the battery can be better.
The nonaqueous electrolyte provided by the invention can be used for solving the problem that the content of the auxiliary additive is 0.05-20 wt% based on the total mass of the nonaqueous electrolyte, the auxiliary additive can form a stable SEI film on the surface of a negative electrode to protect the negative electrode, the cycle performance of a battery is further improved, and excessive addition of the auxiliary additive can cause excessive consumption of active lithium.
According to the provided nonaqueous electrolytic solution of the present invention, the organic solvent may use a nonaqueous solvent conventionally used by those skilled in the art, and for example, may include one or more of dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, propyl methyl carbonate, dipropyl carbonate, ethylene carbonate, propylene carbonate, vinylene carbonate, γ -butyrolactone, sultone, ethylene sulfite, propylene sulfite, methyl sulfide, diethyl sulfite, methyl formate, methyl acrylate, methyl butyrate, and ethyl acetate.
The nonaqueous electrolytic solution according to the present invention, wherein the selection of the lithium salt is not particularly required, may be a lithium salt conventionally used in a nonaqueous electrolytic solution, and may include, for example, one or more of LiBOB, LiPF6, LiBF4, LiSbF6, LiClO4, LiCF3SO3, Li (CF3SO2)2N, LiC4F9SO3, LiAlO4, LiAsF6, LiAlCl4, LiCl, LiI, and low-fatty-acid lithium carbonate. The concentration of the lithium salt is known to those skilled in the art and is generally 0.3 to 3mol/L, preferably 0.8 to 1.2 mol/L.
The preparation method of the non-aqueous electrolyte provided by the invention is a method conventionally used by those skilled in the art, namely, the components (including the lithium salt, the non-aqueous solvent and the additive) are uniformly mixed, and the mixing mode and the mixing sequence are not particularly limited in the invention. For example, the first organic solvent is mixed uniformly, then the lithium salt is added and mixed uniformly, and then the electrolyte additive is added and mixed uniformly, and the auxiliary additive can be added together with the electrolyte additive.
The invention also provides a power battery which comprises a battery shell, and a battery core and a non-aqueous electrolyte which are sealed in the battery shell.
The nonaqueous electrolyte solution is the nonaqueous electrolyte solution, and the battery cell comprises a positive electrode, a negative electrode and a diaphragm. Since the present invention relates to only the improvement of the nonaqueous electrolyte of the battery in the prior art, other compositions and structures of the battery are not particularly limited, and are well known to those skilled in the art, and will not be described herein again.
DETAILED DESCRIPTION OF EMBODIMENT (S) OF INVENTION
Example 1
(1) Preparation of electrolyte
Preparing electrolyte in a glove box, controlling the oxygen content in the glove box to be less than 2ppm, filling the glove box with nitrogen and controlling the purity of the nitrogen in the glove box to be 99.999%, uniformly mixing Ethyl Methyl Carbonate (EMC), Ethylene Carbonate (EC), diethyl carbonate (DEC) and vinylene carbonate according to the mass ratio of 3:4:1:0.2, removing impurities and removing water to obtain a non-aqueous solvent, and adding fully dried lithium hexafluorophosphate into the non-aqueous solvent to prepare the basic electrolyte with the concentration of LiPF6 of 1.2 mol/L. 2wt% of methyl 2, 5-difluorobenzenesulfonate and 2wt% of 2, 3-dicyanopyrazine were added to the base electrolyte to obtain a nonaqueous electrolyte solution of this example, which was designated as C1.
(2) Preparation of the Battery
Uniformly mixing a positive active material NCM622, a conductive agent CNT and a binder PVDF according to the ratio of 100:1.3:1.7, coating the mixture on an aluminum foil to obtain a positive plate, and mixing a negative active material graphite, a conductive agent super P and a binder (CMC/SBR) according to the ratio of 100; 2: 3.9 coating the mixture on a copper foil after uniformly mixing to obtain a negative plate, and coating Al on the surface of the negative plate2O3Coating layerThe PE film of (a) was a separator, and a rectangular battery was produced using the nonaqueous electrolytic solution of this example by a method conventional in the art, and was designated as S1.
Example 2
A nonaqueous electrolytic solution and a prismatic battery were prepared as described in example 1, except that 2wt% of methyl 2-fluorobenzenesulfonate was added to the electrolytic solution instead of 2wt% of methyl 2, 5-difluorobenzenesulfonate, and the resultant nonaqueous electrolytic solution was denoted by C2 and the resultant prismatic battery was denoted by S2.
Example 3
A nonaqueous electrolytic solution and a prismatic battery were prepared as described in example 1, except that 2wt% of methyl 3-fluorobenzenesulfonate was added to the electrolytic solution instead of 2wt% of methyl 2, 5-difluorobenzenesulfonate, and the resultant nonaqueous electrolytic solution was denoted by C3 and the resultant prismatic battery was denoted by S3.
Example 4
A nonaqueous electrolyte and a prismatic battery were prepared as described in example 1, except that 2% by weight of methyl 2, 6-difluorobenzenesulfonate was added to the electrolyte in place of 2% by weight of methyl 2, 5-difluorobenzenesulfonate, the resultant nonaqueous electrolyte was designated as C4, and the resultant prismatic battery was designated as S4.
Example 5
A nonaqueous electrolytic solution and a prismatic battery were prepared as described in example 1, except that 2wt% of methyl 2, 4-difluorobenzenesulfonate was added to the electrolytic solution in place of 2wt% of methyl 2, 5-difluorobenzenesulfonate, the resultant nonaqueous electrolytic solution was denoted by C5, and the resultant prismatic battery was denoted by S5.
Example 6
A nonaqueous electrolytic solution and a prismatic battery were prepared as described in example 1, except that 2% by weight of methyl 2,3, 4-trifluorobenzenesulfonate was added to the electrolytic solution in place of 2% by weight of methyl 2, 5-difluorobenzenesulfonate, and the resultant nonaqueous electrolytic solution was designated as C6, and the resultant prismatic battery was designated as S6.
Example 7
A nonaqueous electrolytic solution and a prismatic battery were prepared as described in example 1, except that 2wt% of 2, 3-dicyanopyridine was added to the electrolytic solution in place of 2wt% of 2, 3-dicyanopyrazine, and the resultant nonaqueous electrolytic solution was designated as C7 and the resultant prismatic battery was designated as S7.
Example 8
A nonaqueous electrolytic solution and a prismatic battery were prepared as described in example 1, except that 2wt% of 6-cyano-2- (4-cyanophenyl) indole was added to the electrolytic solution in place of 2wt% of 2, 3-dicyanopyrazine, and the resultant nonaqueous electrolytic solution was designated as C8 and the resultant prismatic battery was designated as S8.
Example 9
A nonaqueous electrolytic solution and a prismatic battery were prepared as described in example 1, except that the content of methyl 2, 5-difluorobenzenesulfonate was changed to 10% by weight, and the resultant nonaqueous electrolytic solution was designated as C9, and the resultant prismatic battery was designated as S9.
Example 10
A nonaqueous electrolytic solution and a prismatic battery were prepared as described in example 1, except that the content of methyl 2, 5-difluorobenzenesulfonate was changed to 5% by weight, and the resultant nonaqueous electrolytic solution was designated as C10, and the resultant prismatic battery was designated as S10.
Example 11
A nonaqueous electrolytic solution and a prismatic battery were prepared as described in example 1, except that the content of 2, 3-dicyanopyrazine was changed to 10% by weight, and the resultant nonaqueous electrolytic solution was designated as C11 and the resultant prismatic battery was designated as S11.
Example 12
A nonaqueous electrolytic solution and a prismatic battery were prepared as described in example 1, except that the content of 2, 3-dicyanopyrazine was changed to 7.5% by weight, and the resultant nonaqueous electrolytic solution was designated as C12, and the resultant prismatic battery was designated as S12.
Example 13
A nonaqueous electrolyte and a prismatic cell were prepared as described in example 1, except that 5wt% of methyl 2, 5-difluorobenzenesulfonate and 5wt% of 2, 3-dicyanopyrazine were added to the base electrolyte, the resultant nonaqueous electrolyte was designated as C13, and the resultant prismatic cell was designated as S13.
Example 14
A nonaqueous electrolyte and a prismatic cell were prepared as described in example 1, except that vinylene carbonate was replaced with fluoroethylene carbonate in the preparation of the base electrolyte, and the nonaqueous electrolyte and the prismatic cell were each designated as C13 and S13, respectively.
Comparative example 1
A nonaqueous electrolyte and a prismatic cell were prepared as described in example 1, except that the additives described herein were not added to the base electrolyte, the resulting nonaqueous electrolyte was designated DC1 and the resulting prismatic cell was designated DS 1.
Comparative example 2
A nonaqueous electrolyte and a prismatic cell were prepared as described in example 1, except that 2% by weight of methyl 2, 5-difluorobenzenesulfonate was separately added to the base electrolyte, and the resultant nonaqueous electrolyte was designated as DC2, and the resultant prismatic cell was designated as DS 2.
Comparative example 3
A nonaqueous electrolytic solution and a prismatic battery were prepared as described in example 1, except that 2% by weight of 2, 3-dicyanopyrazine was added alone to the base electrolytic solution, and the resultant nonaqueous electrolytic solution was designated as DC2 and the resultant prismatic battery was designated as DS 2.
Performance testing
150 ℃ storage safety test
The prismatic cell samples S1-S14 and DS1-DS3 were charged to 100% SOC at a constant current of 0.1C at 25 + -2 deg.C, the samples were placed in an oven at a rate of 5 + -2 deg.C per minute to 150 + -2 deg.C for 30 minutes to turn to a constant temperature, and the cells passed standard without fire and explosion, and the test results are shown in Table 1.
TABLE 1
From the test results in table 1, when the electrolyte is added with the fluorobenzenesulfonate alone or the nitrogen-containing dicyan heterocyclic compound or not, and the electrolyte is applied to the battery, the 150 ℃ storage safety test of the battery cannot pass, but the fluorobenzenesulfonate and the nitrogen-containing heterocyclic dinitrile compound are added into the electrolyte together, and the electrolyte is applied to the battery, the 150 ℃ storage safety test passing rate of the battery is remarkably improved, so that the safety performance of the battery is greatly improved.
Claims (12)
1. A nonaqueous electrolyte solution comprising a lithium salt, an organic solvent and an additive, wherein the additive comprises a fluorobenzenesulfonate having a structural formula shown in formula (I):
formula (I)
Wherein R is selected from one of alkyl with 1-6 carbon atoms, halogenated alkyl with 1-6 carbon atoms, alkenyl with 2-6 carbon atoms, alkynyl with 2-6 carbon atoms, aryl and halogenated aryl; r1, R2, R3 and R4 are respectively and independently selected from one of H, Cl, F, Br, I, alkyl with 1-6 carbon atoms, halogenated alkyl with 1-6 carbon atoms, alkenyl with 2-6 carbon atoms and alkynyl with 2-6 carbon atoms, and at least one of R1, R2, R3 and R4 is F;
the structural formula of the nitrogen-containing heterocyclic dinitrile compound is shown as the formula (II):
(ii) a In the formula, R5 is a five-membered heterocycle containing nitrogen or a six-membered heterocycle containing nitrogen;
the content of the nitrogen-containing heterocyclic dinitrile compound is 2-10 wt% based on the total mass of the nonaqueous electrolytic solution, and the mass ratio of the fluorobenzenesulfonate to the nitrogen-containing heterocyclic dinitrile compound is 0.2: 1-5: 1.
2. The nonaqueous electrolytic solution of claim 1, wherein the fluorobenzenesulfonate comprises one or more of methyl 2-fluorobenzenesulfonate, methyl 3-fluorobenzenesulfonate, methyl 4-fluorobenzenesulfonate, methyl 2, 4-difluorobenzenesulfonate, methyl 2, 5-difluorobenzenesulfonate, methyl 2, 6-difluorobenzenesulfonate, methyl 3, 4-difluorobenzenesulfonate, and methyl 3, 5-difluorobenzenesulfonate, methyl 2,3, 4-trifluorobenzenesulfonate.
3. The nonaqueous electrolytic solution of claim 2, wherein the fluorobenzenesulfonate comprises one or more of methyl 2-fluorobenzenesulfonate, methyl 3-fluorobenzenesulfonate, methyl 2, 4-difluorobenzenesulfonate, methyl 2, 5-difluorobenzenesulfonate and methyl 2, 6-difluorobenzenesulfonate.
4. The nonaqueous electrolytic solution of claim 1, wherein the nitrogen-containing heterocyclic dinitrile compound comprises one or more of 2, 3-dicyanopyrazine, 2, 3-dicyanopyridine, 2, 4-dicyanopyridine, and 6-cyano-2- (4-cyanophenyl) indole.
5. The nonaqueous electrolytic solution of claim 4, wherein the nitrogen-containing heterocyclic dinitrile compound comprises one or more of 2, 3-dicyanopyrazine and 6-cyano-2- (4-cyanobenzene) indole.
6. The nonaqueous electrolytic solution of claim 1, wherein the content of the fluorobenzenesulfonate is 2 to 10wt% based on the total mass of the nonaqueous electrolytic solution.
7. The nonaqueous electrolytic solution of claim 1, further comprising an auxiliary additive, wherein the auxiliary additive comprises one or more of 1,3 propane sultone, 1,4 butane sultone, propenyl-1, 3-sultone, vinyl sulfate, propylene sulfate, butylene sulfite, vinylene carbonate, fluoroethylene carbonate, lithium bis (fluorosulfonyl) imide in bis (oxalato) borate.
8. The nonaqueous electrolytic solution of claim 7, wherein the content of the auxiliary additive is 0.05 wt% to 20 wt% based on the total mass of the nonaqueous electrolytic solution.
9. The nonaqueous electrolytic solution of claim 1, wherein the organic solvent is one or more selected from dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, propyl methyl carbonate, dipropyl carbonate, ethylene carbonate, propylene carbonate, vinylene carbonate, gamma-butyrolactone, sultone, ethylene sulfite, propylene sulfite, methyl sulfide, diethyl sulfite, methyl formate, methyl acrylate, methyl butyrate, and ethyl acetate.
10. The nonaqueous electrolytic solution of claim 1, wherein the lithium salt is selected from the group consisting of LiBOB and LiPF6、LiBF4、LiSbF6、LiClO4、LiCF3SO3、Li(CF3SO2)2N、LiC4F9SO3、LiAlO4、LiAsF6、LiAlCl4One or more of LiCl, LiI and low-fatty acid lithium carbonate, wherein the concentration of the lithium salt is 0.3-3 mol/L.
11. A battery comprising a battery case, and a cell and a nonaqueous electrolytic solution sealed in the battery case, the cell comprising a positive electrode, a negative electrode and a separator, characterized in that the nonaqueous electrolytic solution is the nonaqueous electrolytic solution according to any one of claims 1 to 10.
12. An electric vehicle comprising the battery of claim 11.
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