CN113956282A - Electrolyte additive, electrolyte and lithium secondary battery - Google Patents
Electrolyte additive, electrolyte and lithium secondary battery Download PDFInfo
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- CN113956282A CN113956282A CN202111223946.0A CN202111223946A CN113956282A CN 113956282 A CN113956282 A CN 113956282A CN 202111223946 A CN202111223946 A CN 202111223946A CN 113956282 A CN113956282 A CN 113956282A
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- Prior art keywords
- electrolyte
- lithium
- additive
- solvent
- carbonate
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- 239000003792 electrolyte Substances 0.000 title claims abstract description 41
- 229910052744 lithium Inorganic materials 0.000 title claims abstract description 36
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 title claims abstract description 35
- 239000002000 Electrolyte additive Substances 0.000 title claims abstract description 17
- 239000000654 additive Substances 0.000 claims abstract description 32
- 230000000996 additive effect Effects 0.000 claims abstract description 32
- 150000001875 compounds Chemical class 0.000 claims abstract description 11
- 239000002904 solvent Substances 0.000 claims description 24
- 229910003002 lithium salt Inorganic materials 0.000 claims description 15
- 159000000002 lithium salts Chemical class 0.000 claims description 15
- -1 lithium hexafluorophosphate Chemical compound 0.000 claims description 12
- OIFBSDVPJOWBCH-UHFFFAOYSA-N Diethyl carbonate Chemical compound CCOC(=O)OCC OIFBSDVPJOWBCH-UHFFFAOYSA-N 0.000 claims description 6
- XEKOWRVHYACXOJ-UHFFFAOYSA-N Ethyl acetate Chemical compound CCOC(C)=O XEKOWRVHYACXOJ-UHFFFAOYSA-N 0.000 claims description 6
- KMTRUDSVKNLOMY-UHFFFAOYSA-N Ethylene carbonate Chemical compound O=C1OCCO1 KMTRUDSVKNLOMY-UHFFFAOYSA-N 0.000 claims description 6
- 150000001733 carboxylic acid esters Chemical class 0.000 claims description 6
- JBTWLSYIZRCDFO-UHFFFAOYSA-N ethyl methyl carbonate Chemical compound CCOC(=O)OC JBTWLSYIZRCDFO-UHFFFAOYSA-N 0.000 claims description 6
- 229910052796 boron Inorganic materials 0.000 claims description 4
- 150000005678 chain carbonates Chemical class 0.000 claims description 4
- 150000005676 cyclic carbonates Chemical class 0.000 claims description 4
- 239000007773 negative electrode material Substances 0.000 claims description 4
- 229910000314 transition metal oxide Inorganic materials 0.000 claims description 4
- 229910052731 fluorine Inorganic materials 0.000 claims description 3
- 239000007774 positive electrode material Substances 0.000 claims description 3
- UHOPWFKONJYLCF-UHFFFAOYSA-N 2-(2-sulfanylethyl)isoindole-1,3-dione Chemical compound C1=CC=C2C(=O)N(CCS)C(=O)C2=C1 UHOPWFKONJYLCF-UHFFFAOYSA-N 0.000 claims description 2
- SBLRHMKNNHXPHG-UHFFFAOYSA-N 4-fluoro-1,3-dioxolan-2-one Chemical compound FC1COC(=O)O1 SBLRHMKNNHXPHG-UHFFFAOYSA-N 0.000 claims description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 2
- 229910012701 LiCo1-xMxO2 Inorganic materials 0.000 claims description 2
- 229910012938 LiCo1−xMxO2 Inorganic materials 0.000 claims description 2
- 229910032387 LiCoO2 Inorganic materials 0.000 claims description 2
- 229910011902 LiFe1-xMxPO4 Inorganic materials 0.000 claims description 2
- 229910010595 LiFe1−xMxPO4 Inorganic materials 0.000 claims description 2
- 229910052493 LiFePO4 Inorganic materials 0.000 claims description 2
- 229910002993 LiMnO2 Inorganic materials 0.000 claims description 2
- 229910002097 Lithium manganese(III,IV) oxide Inorganic materials 0.000 claims description 2
- 229910016289 MxO2 Inorganic materials 0.000 claims description 2
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 claims description 2
- 125000000217 alkyl group Chemical group 0.000 claims description 2
- 229910052782 aluminium Inorganic materials 0.000 claims description 2
- 229910052804 chromium Inorganic materials 0.000 claims description 2
- IEJIGPNLZYLLBP-UHFFFAOYSA-N dimethyl carbonate Chemical compound COC(=O)OC IEJIGPNLZYLLBP-UHFFFAOYSA-N 0.000 claims description 2
- 239000010439 graphite Substances 0.000 claims description 2
- 229910002804 graphite Inorganic materials 0.000 claims description 2
- 229910001496 lithium tetrafluoroborate Inorganic materials 0.000 claims description 2
- 229910052749 magnesium Inorganic materials 0.000 claims description 2
- 229910052748 manganese Inorganic materials 0.000 claims description 2
- 229910052750 molybdenum Inorganic materials 0.000 claims description 2
- YKYONYBAUNKHLG-UHFFFAOYSA-N n-Propyl acetate Natural products CCCOC(C)=O YKYONYBAUNKHLG-UHFFFAOYSA-N 0.000 claims description 2
- 229910052759 nickel Inorganic materials 0.000 claims description 2
- 229940090181 propyl acetate Drugs 0.000 claims description 2
- RUOJZAUFBMNUDX-UHFFFAOYSA-N propylene carbonate Chemical compound CC1COC(=O)O1 RUOJZAUFBMNUDX-UHFFFAOYSA-N 0.000 claims description 2
- 239000002153 silicon-carbon composite material Substances 0.000 claims description 2
- 229910052719 titanium Inorganic materials 0.000 claims description 2
- NQPDZGIKBAWPEJ-UHFFFAOYSA-N valeric acid Chemical compound CCCCC(O)=O NQPDZGIKBAWPEJ-UHFFFAOYSA-N 0.000 claims description 2
- 229910052720 vanadium Inorganic materials 0.000 claims description 2
- 229910052726 zirconium Inorganic materials 0.000 claims description 2
- SSBFISCARUPWGN-UHFFFAOYSA-N [Li].C(C(=O)F)(=O)F Chemical compound [Li].C(C(=O)F)(=O)F SSBFISCARUPWGN-UHFFFAOYSA-N 0.000 claims 1
- RBYFNZOIUUXJQD-UHFFFAOYSA-J tetralithium oxalate Chemical compound [Li+].[Li+].[Li+].[Li+].[O-]C(=O)C([O-])=O.[O-]C(=O)C([O-])=O RBYFNZOIUUXJQD-UHFFFAOYSA-J 0.000 claims 1
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 abstract description 19
- 229910001416 lithium ion Inorganic materials 0.000 abstract description 19
- 239000000126 substance Substances 0.000 description 20
- 230000000052 comparative effect Effects 0.000 description 10
- 125000000623 heterocyclic group Chemical group 0.000 description 7
- 238000007599 discharging Methods 0.000 description 6
- 239000011255 nonaqueous electrolyte Substances 0.000 description 6
- 238000012360 testing method Methods 0.000 description 5
- 238000011161 development Methods 0.000 description 4
- 230000014759 maintenance of location Effects 0.000 description 4
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical group [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 3
- 239000008151 electrolyte solution Substances 0.000 description 3
- 238000000034 method Methods 0.000 description 3
- 239000003960 organic solvent Substances 0.000 description 3
- 238000011084 recovery Methods 0.000 description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- 230000002378 acidificating effect Effects 0.000 description 2
- 125000004429 atom Chemical group 0.000 description 2
- 150000007942 carboxylates Chemical class 0.000 description 2
- 229940125904 compound 1 Drugs 0.000 description 2
- IQPQWNKOIGAROB-UHFFFAOYSA-N isocyanate group Chemical group [N-]=C=O IQPQWNKOIGAROB-UHFFFAOYSA-N 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000011160 research Methods 0.000 description 2
- 238000006467 substitution reaction Methods 0.000 description 2
- 229910015900 BF3 Inorganic materials 0.000 description 1
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical group [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 description 1
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 1
- YCKRFDGAMUMZLT-UHFFFAOYSA-N Fluorine atom Chemical compound [F] YCKRFDGAMUMZLT-UHFFFAOYSA-N 0.000 description 1
- 229910011328 LiNi0.6Co0.2Mn0.2O2 Inorganic materials 0.000 description 1
- 229910013872 LiPF Inorganic materials 0.000 description 1
- 229910013870 LiPF 6 Inorganic materials 0.000 description 1
- 101150058243 Lipf gene Proteins 0.000 description 1
- 239000004698 Polyethylene Substances 0.000 description 1
- 229910008284 Si—F Inorganic materials 0.000 description 1
- HFCVPDYCRZVZDF-UHFFFAOYSA-N [Li+].[Co+2].[Ni+2].[O-][Mn]([O-])(=O)=O Chemical compound [Li+].[Co+2].[Ni+2].[O-][Mn]([O-])(=O)=O HFCVPDYCRZVZDF-UHFFFAOYSA-N 0.000 description 1
- SYRDSFGUUQPYOB-UHFFFAOYSA-N [Li+].[Li+].[Li+].[O-]B([O-])[O-].FC(=O)C(F)=O Chemical compound [Li+].[Li+].[Li+].[O-]B([O-])[O-].FC(=O)C(F)=O SYRDSFGUUQPYOB-UHFFFAOYSA-N 0.000 description 1
- 230000003044 adaptive effect Effects 0.000 description 1
- 229910052783 alkali metal Inorganic materials 0.000 description 1
- 125000003545 alkoxy group Chemical group 0.000 description 1
- 239000010405 anode material Substances 0.000 description 1
- 229910021383 artificial graphite Inorganic materials 0.000 description 1
- 125000003118 aryl group Chemical group 0.000 description 1
- 125000004104 aryloxy group Chemical group 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- WTEOIRVLGSZEPR-UHFFFAOYSA-N boron trifluoride Substances FB(F)F WTEOIRVLGSZEPR-UHFFFAOYSA-N 0.000 description 1
- 125000005587 carbonate group Chemical group 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 230000002950 deficient Effects 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- JZZIHCLFHIXETF-UHFFFAOYSA-N dimethylsilicon Chemical compound C[Si]C JZZIHCLFHIXETF-UHFFFAOYSA-N 0.000 description 1
- 238000010494 dissociation reaction Methods 0.000 description 1
- 230000005593 dissociations Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000004146 energy storage Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000003912 environmental pollution Methods 0.000 description 1
- 239000011737 fluorine Substances 0.000 description 1
- ZHPNWZCWUUJAJC-UHFFFAOYSA-N fluorosilicon Chemical compound [Si]F ZHPNWZCWUUJAJC-UHFFFAOYSA-N 0.000 description 1
- 239000002803 fossil fuel Substances 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 125000005843 halogen group Chemical group 0.000 description 1
- 150000002391 heterocyclic compounds Chemical class 0.000 description 1
- 125000002883 imidazolyl group Chemical group 0.000 description 1
- DEUISMFZZMAAOJ-UHFFFAOYSA-N lithium dihydrogen borate oxalic acid Chemical compound B([O-])(O)O.C(C(=O)O)(=O)O.C(C(=O)O)(=O)O.[Li+] DEUISMFZZMAAOJ-UHFFFAOYSA-N 0.000 description 1
- FUJCRWPEOMXPAD-UHFFFAOYSA-N lithium oxide Chemical compound [Li+].[Li+].[O-2] FUJCRWPEOMXPAD-UHFFFAOYSA-N 0.000 description 1
- 229910001947 lithium oxide Inorganic materials 0.000 description 1
- PXHVJJICTQNCMI-UHFFFAOYSA-N nickel Substances [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229920000573 polyethylene Polymers 0.000 description 1
- 125000003373 pyrazinyl group Chemical group 0.000 description 1
- 125000003226 pyrazolyl group Chemical group 0.000 description 1
- 125000002098 pyridazinyl group Chemical group 0.000 description 1
- 125000004076 pyridyl group Chemical group 0.000 description 1
- 125000000714 pyrimidinyl group Chemical group 0.000 description 1
- 125000000168 pyrrolyl group Chemical group 0.000 description 1
- 239000007784 solid electrolyte Substances 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07F—ACYCLIC, CARBOCYCLIC OR HETEROCYCLIC COMPOUNDS CONTAINING ELEMENTS OTHER THAN CARBON, HYDROGEN, HALOGEN, OXYGEN, NITROGEN, SULFUR, SELENIUM OR TELLURIUM
- C07F7/00—Compounds containing elements of Groups 4 or 14 of the Periodic Table
- C07F7/02—Silicon compounds
- C07F7/21—Cyclic compounds having at least one ring containing silicon, but no carbon in the ring
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
- H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
-
- 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
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
- H01M10/4235—Safety or regulating additives or arrangements in electrodes, separators or electrolyte
-
- 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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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- General Chemical & Material Sciences (AREA)
- Manufacturing & Machinery (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- Organic Chemistry (AREA)
- Materials Engineering (AREA)
- Physics & Mathematics (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- General Physics & Mathematics (AREA)
- Inorganic Chemistry (AREA)
- Secondary Cells (AREA)
Abstract
The invention belongs to the technical field of lithium secondary batteries, and particularly relates to an electrolyte additive which is a compound with a structure shown as a structural formula I:
wherein R1, R2 and R3 are respectively independent H or contain C1‑C3Or 1-fluorodimethylsilyl group. The additive has good cycle performance and high-temperature storage and low-temperature performance under high voltage after being applied to lithium ion battery electrolyte. Meanwhile, the invention also discloses an electrolyte and a lithium ion battery.
Description
Technical Field
The invention relates to the technical field of lithium ion batteries, in particular to an electrolyte additive, an electrolyte and a lithium secondary battery.
Background
In recent years, because of environmental pollution and the scarcity of fossil fuel resources, the development direction of new energy of all countries in the world is formed by replacing increasingly exhausted fossil energy with green energy. Since the advent of commercial lithium ion batteries, the lithium ion battery industry, which is outstanding in terms of environmental protection, has been rapidly developed and is now widely used in the fields of pure electric vehicles, hybrid electric vehicles, portable energy storage devices, and the like. Among them, the lithium ion secondary battery has met with the unprecedented development opportunities as the most potential power battery system in electric vehicles and plug-in hybrid electric vehicles, and at the same time, it also puts more stringent requirements on the energy density, safety performance, storage performance, etc. of the lithium ion battery.
The electrolyte is an important component in the battery, is used as a bridge of a positive electrode material and a negative electrode material, and plays an important role in the aspects of lithium ion transmission and the like. Conventional lithium ion battery electrolytes generally consist of an organic solvent, a lithium salt, and an additive. The conventional electrolyte can not meet the requirements of a high-voltage lithium ion battery, so that the development of the high-voltage electrolyte is crucial, and the development of an adaptive electrolyte additive for improving the interface structure of an electrode and the electrolyte is one of the most economical and effective methods for improving the electrochemical performance of the lithium ion battery, and is widely concerned by various circles.
CN201610194360.9 discloses a lithium ion battery electrolyte, which comprises a lithium salt, an additive and an organic solvent, wherein the additive is a nitrogen heterocycle-boron trifluoride coordination compound and a silicon-oxygen-phosphorus ester compound, wherein the nitrogen-containing heterocycle is at least one selected from pyridyl-containing heterocycle, pyridazinyl-containing heterocycle, pyrimidinyl-containing heterocycle, pyrazinyl-containing heterocycle, pyrrolyl-containing heterocycle, pyrazolyl-containing heterocycle and imidazolyl-containing heterocycle; the organic solvent is carbonate, carboxylate or the mixture of the carbonate and the carboxylate. The lithium salt is lithium hexafluorophosphate (LiPF 6). By adding the additive with the structural formula into the electrolyte, a dense Solid Electrolyte Interface (SEI) film with small impedance is formed on the surface of the negative electrode sheet, so that substances such as oxygen, lithium oxide and the like can be adsorbed on the positive electrode, acidic substances generated in the electrolyte can be neutralized, and corrosion of acidic substances generated in the electrolyte, such as PF5, HF, CO2 and the like, on the SEI film is reduced.
In the prior art, the application of heterocyclic compounds to electrolytes as film formation or other electrical properties is helpful.
CN201610615091.9 discloses a nonaqueous electrolyte solution and a nonaqueous electrolyte secondary battery using a carboxylic acid ester as a main solvent. A non-aqueous electrolyte comprises a solvent, an additive, an alkali metal salt and chain carboxylic ester with a special structure;
the structure of the additive is as follows:
CN201280008556.4 discloses a nonaqueous electrolyte solution in which deterioration of capacity and generation of gas during high-temperature storage of a nonaqueous electrolyte battery are improved, and a nonaqueous electrolyte battery using the same. The above object is achieved by using (A) a compound having at least 2 isocyanate groups in a molecule and a nonaqueous electrolytic solution containing a compound having at least 2 isocyanate groups in a molecule in a specific content.
The structural formula is as follows:
X1～X6each independently represents a halogen atom, an alkyl group, an aryl group, an alkoxy group or an aryloxy group, which are optionally the same as or different from each other.
The direction of the important research of the scheme is as follows: further research is carried out on the fluorine-containing dimethyl silicon-based nitrogen-silicon-boron cyclohexane compound to obtain the electrolyte with excellent high-pressure resistance and high-low temperature resistance.
Disclosure of Invention
An object of the present invention is to provide an electrolyte additive for lithium ion battery electrolytes, which has good cycle performance at high voltage and high-temperature storage and low-temperature performance.
The second object of the present invention is to provide an electrolyte for a lithium ion battery, which contains the above electrolyte additive and has good cycle performance at high voltage as well as high-temperature storage and low-temperature performance.
The invention also aims to provide a lithium ion battery which contains the electrolyte, effectively inhibits cycle gassing, and has good cycle performance and high-temperature storage and low-temperature performance under high voltage.
To achieve the above objects, the present invention provides an electrolyte additive, which is a compound having a structure represented by formula i:
wherein R1, R2 and R3 are respectively independent H or contain C1-C3Or 1-fluorodimethylsilyl group.
Meanwhile, the invention also discloses an electrolyte, which comprises lithium salt, a solvent and an additive, wherein the additive comprises the electrolyte additive.
In the electrolyte, the structural formula I is any one of the following compounds:
in the electrolyte, the mass percentage of the electrolyte additive to the total mass of the lithium salt and the solvent is 0.01-0.2%.
Preferably, the mass percentage of the electrolyte additive to the total mass of the lithium salt and the solvent is 0.03 to 0.2 percent.
Preferably, the mass percentage of the electrolyte additive to the total mass of the lithium salt and the solvent is 0.05-0.15%.
In the above electrolyte, the lithium salt is at least one selected from the group consisting of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium dioxalate borate, lithium difluorooxalate borate, lithium bis fluorosulfonylimide and lithium bis (trifluoromethyl) sulfonyl imide.
In the above electrolyte, the concentration of the lithium salt in the electrolyte is 0.5M to 1.5M.
Specifically, the concentration of the lithium salt of the electrolyte of the present invention in the electrolyte may be, but is not limited to, 0.5M, 0.75M, 1M, 1.25M, 1.5M.
In the above electrolyte, the solvent is selected from one or more of a chain carbonate solvent, a cyclic carbonate solvent, and a carboxylic ester solvent;
the cyclic carbonate solvent is at least one of ethylene carbonate, fluoroethylene carbonate and propylene carbonate;
the chain carbonate solvent refers to at least one of dimethyl carbonate, diethyl carbonate and methyl ethyl carbonate;
the carboxylic ester solvent refers to at least one of propyl acetate, ethyl acetate and propyl propionate.
Finally, the invention also discloses a lithium secondary battery, which comprises a positive electrode, a negative electrode and the electrolyte solution;
wherein: the positive electrode material is selected from transition metal oxide of lithium, wherein the transition metal oxide of lithium is LiCoO2、LiMn2O4、LiMnO2、Li2MnO4、LiFePO4、Li1+aMn1-xMxO2、LiCo1-xMxO2、LiFe1-xMxPO4、Li2Mn1- xO4Wherein M is one or more selected from Ni, Co, Mn, Al, Cr, Mg, Zr, Mo, V, Ti, B and F, and a is more than or equal to 0<0.2，0≤x<1；
The negative electrode material is selected from at least one of graphite, silicon-carbon composite material and lithium titanate.
The invention has the following beneficial effects:
the electrolyte additive of the invention has good cycle performance and high-temperature storage and low-temperature performance under high voltage.
The reason for this is that: the scheme adopts a nitrogen-silicon-boron cyclohexane compound, wherein the central atom of the boron atom is in an electron-deficient state and can complex PF 6-and F-, so that the dissociation degree of lithium salt is improved, the LiF content on the surface of an electrode is reduced, and the high-voltage performance of the battery is improved; and because of the Si-F bond, the stable PF 5-fluorine silicon complex can be formed in the electrolyte, so that the further decomposition reaction of the electrolyte is prevented, and the thermal stability of the lithium ion battery is improved. It is considered to be an electrolyte additive for lithium ion battery electrolytes having good cycle properties at high voltage as well as high temperature storage and low temperature properties.
Detailed Description
The technical solutions of the present invention are described in further detail below, but the present invention is not limited thereto.
Example 1
In this example, a solvent comprising Ethyl Methyl Carbonate (EMC), Ethylene Carbonate (EC), diethyl carbonate (DEC) and a mixture thereof at a mass ratio of (5:3:2) was prepared, and 1mol of lithium hexafluorophosphate (LiPF) was added6) The electrolyte solution (100 g).
0.1g of additive of the chemical formula 1 is added into the electrolyte, and the anode material is nickel cobalt lithium manganate ternary material LiNi0.6Co0.2Mn0.2O2(ii) a The negative electrode material is artificial graphite; the diaphragm is a polyethylene film coated ceramic diaphragm. And assembling the soft package lithium secondary battery according to a conventional method.
Example 2
The same as example 1, except that the additive of chemical formula 2 was used instead of the additive of chemical formula 1 in example 1.
Example 3
The same as example 1, except that the additive of chemical formula 3 was used instead of the additive of chemical formula 1 in example 1.
Example 4
The same as example 1, except that the additive of chemical formula 4 was used instead of the additive of chemical formula 1 in example 1.
Example 5
The same as example 1, except that the additive of chemical formula 5 was used instead of the additive of chemical formula 1 in example 1.
Example 6
The same as example 1, except that the additive of chemical formula 6 was used instead of the additive of chemical formula 1 in example 1.
Example 7
The same as example 1 except that the additive of chemical formula 7 was used instead of the additive of chemical formula 1 in example 1.
Example 8
The same as example 1 except that the additive of chemical formula 8 was used instead of the additive of chemical formula 1 in example 1.
Example 9
The same as example 1 except that the amount of the additive (chemical formula 1) was adjusted to 0.02 g.
Example 10
The same as example 1 except that the amount of the additive (chemical formula 1) was adjusted to 0.2 g.
Example 11
The same as example 1, except that the solvent ratio EC: DEC: EMC 1:1:1 was adjusted to (EMC: EC: DEC: 5:3: 2).
Comparative example 1
The same as example 1 was repeated except that the electrolyte contained no additive.
Comparative example 2
Comparative example 2 is different from comparative example 1 in that the additive in comparative example 1 is replaced with a compound represented by the formula:
2. the lithium secondary batteries of examples 1 to 11 and comparative examples 1 to 2 were subjected to normal temperature electrical property, high temperature cycle property, high temperature storage property, and low temperature property tests, and the test method was:
normal temperature cycle performance: and (2) placing the lithium secondary battery at 25 ℃, charging the lithium secondary battery to 4.5V at a constant current and a constant voltage of 1.0C and charging the lithium secondary battery to a cut-off current of 0.05V at a constant voltage of 4.5V, then discharging the lithium secondary battery at a constant current of 1.0C, wherein the discharge capacity is marked as C0, and the charging and discharging process is repeated for 1000 weeks to obtain the discharge capacity C1000 at the 1000 th week, and the capacity retention rate is C1000/C0 x 100%.
High temperature cycle performance: and (2) placing the lithium secondary battery in a constant temperature box at 45 ℃, charging the lithium secondary battery to 4.5V at a constant current of 1.0C at 45 ℃, charging the lithium secondary battery to a cut-off current of 0.05C at a constant voltage, then discharging the lithium secondary battery at a constant current of 1.0C, wherein the discharge capacity is marked as C0, and repeating the charging and discharging process for 1000 weeks to obtain the discharge capacity C1000 at the 1000 th week, and the capacity retention rate is C1000/C0 as 100%.
High temperature storage performance: charging the formed lithium ion battery to 4.5V at normal temperature by using a 1.0C current constant current and constant voltage, measuring the initial capacity of the battery, and recording the thickness of the tested lithium ion battery as H0; then storing the lithium secondary battery in an environment of 60 ℃ for 30 days, taking out the lithium secondary battery, testing the thickness H1, cooling the lithium secondary battery to room temperature, discharging the lithium secondary battery to 2.75V at 1C current, and testing the discharge capacity of the lithium secondary battery; then, the lithium secondary battery was charged at a constant current and a constant voltage of 1C to 4.5V and then discharged at a current of 1.0C to 2.75V, and the recovery capacity of the lithium secondary battery was measured.
High-temperature storage capacity retention rate (discharge capacity after storage/discharge capacity before storage) × 100%
High-temperature storage capacity recovery rate (recovery capacity after storage/discharge capacity before storage) × 100%
Thickness expansion ratio (H1-H0)/H0X 100%
Low-temperature storage performance: charging the lithium secondary battery at a constant current of 1.0 ℃ to a voltage of 4.5V at normal temperature, placing the battery in a low-temperature cabinet at the temperature of minus 20 ℃ for more than 4h, and discharging at the temperature of 0.5C to 2.75V when the temperature of the battery is reduced to minus 20 ℃.
-20 ℃ discharge capacity retention rate (-20 ℃ 1C discharge capacity/room temperature discharge capacity) × 100%
The test results are shown in table 1:
TABLE 1 test results of high-temperature and low-temperature performance of lithium secondary battery
By way of comparison of example 1, examples 9 to 11, we have found that the optimum amount of additive is 0.1%. By comparing examples 1 to 11 with comparative examples 1 to 2, we found that the fluorine-silicon-containing boronitride compound has more outstanding comprehensive properties in terms of normal temperature cycle, high temperature storage and low temperature discharge performance. This shows that the material has the characteristics of high voltage resistance and high thermal stability.
It is also worth noting that the results of example 1 and comparative example 2 show that the compound 1 has better performance than the additive of comparative example 2 in normal temperature cycle, high temperature storage and low temperature discharge. This indicates that our silatrane compound binds F more readily than comparative example 2-The LiF content in the interface film is reduced, and the ionic conductivity of the interface film is improved.
By comparing example 1 with examples 2 to 4, we have found that compound 1 has superior overall properties to compounds 2, 3 and 4, which illustrates that it contains only one fluorochemical silicon group, and that the fluorochemical silicon group is better in the ortho position than in the para position of the B atom, which may be related to the effect of steric hindrance on the fluorochemical silicon group.
The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and all such changes, modifications, substitutions, combinations, and simplifications are intended to be included in the scope of the present invention.
Claims (8)
1. An electrolyte additive, characterized by a compound having a structure represented by formula i:
wherein, R1, R2 and R3 are respectively independent H, alkyl containing C1-C3 or 1-fluorodimethylsilyl, and at least 1-fluorodimethylsilyl is contained in R1, R2 and R3.
2. An electrolyte comprising a lithium salt, a solvent and an additive, wherein the additive comprises the electrolyte additive of claim 1.
3. The electrolyte of claim 2, wherein the structural formula i is any one of the following compounds:
4. the electrolyte according to claim 2, wherein the mass percentage of the electrolyte additive to the total mass of the lithium salt and the solvent is 0.01 to 0.2%.
5. The electrolyte of claim 2, wherein the lithium salt is selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium dioxalate, lithium difluorooxalate, lithium difluorosulfonimide, lithium bistrifluoromethylsulfonimide.
6. The electrolyte of claim 2, wherein the concentration of the lithium salt in the electrolyte is between 0.5M and 1.5M.
7. The electrolyte of claim 2, wherein the solvent is selected from one or more of a chain carbonate solvent, a cyclic carbonate solvent, and a carboxylic ester solvent;
the cyclic carbonate solvent is at least one of ethylene carbonate, fluoroethylene carbonate and propylene carbonate;
the chain carbonate solvent refers to at least one of dimethyl carbonate, diethyl carbonate and methyl ethyl carbonate;
the carboxylic ester solvent refers to at least one of propyl acetate, ethyl acetate and propyl propionate.
8. A lithium secondary battery characterized in that: the lithium secondary battery comprises a positive electrode, a negative electrode and the electrolyte according to any one of claims 2 to 6;
wherein: the positive electrode material is selected from transition metal oxide of lithium, wherein the transition metal oxide of lithium is LiCoO2、LiMn2O4、LiMnO2、Li2MnO4、LiFePO4、Li1+aMn1-xMxO2、LiCo1-xMxO2、LiFe1-xMxPO4、Li2Mn1-xO4Wherein M is one or more selected from Ni, Co, Mn, Al, Cr, Mg, Zr, Mo, V, Ti, B and F, and a is more than or equal to 0<0.2，0≤x<1；
The negative electrode material is selected from at least one of graphite, silicon-carbon composite material and lithium titanate.
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| CN114497743A (en) * | 2022-02-23 | 2022-05-13 | 珠海市赛纬电子材料股份有限公司 | Electrolyte applied to alkali metal battery and alkali metal battery thereof |
| CN114497743B (en) * | 2022-02-23 | 2022-09-27 | 珠海市赛纬电子材料股份有限公司 | Electrolyte applied to alkali metal battery and alkali metal battery thereof |
| WO2023159798A1 (en) * | 2022-02-23 | 2023-08-31 | 珠海市赛纬电子材料股份有限公司 | Electrolyte used for alkali metal battery and alkali metal battery thereof |
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