CN116722217A - Electrolyte and battery - Google Patents
Electrolyte and battery Download PDFInfo
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- CN116722217A CN116722217A CN202310681696.8A CN202310681696A CN116722217A CN 116722217 A CN116722217 A CN 116722217A CN 202310681696 A CN202310681696 A CN 202310681696A CN 116722217 A CN116722217 A CN 116722217A
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- battery
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- 239000003792 electrolyte Substances 0.000 title claims abstract description 97
- 239000000654 additive Substances 0.000 claims abstract description 94
- 230000000996 additive effect Effects 0.000 claims abstract description 90
- 150000003839 salts Chemical class 0.000 claims abstract description 25
- 239000002904 solvent Substances 0.000 claims abstract description 17
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 claims description 31
- 229910052744 lithium Inorganic materials 0.000 claims description 31
- XEKOWRVHYACXOJ-UHFFFAOYSA-N Ethyl acetate Chemical compound CCOC(C)=O XEKOWRVHYACXOJ-UHFFFAOYSA-N 0.000 claims description 18
- -1 lithium hexafluorophosphate Chemical compound 0.000 claims description 16
- FKRCODPIKNYEAC-UHFFFAOYSA-N ethyl propionate Chemical compound CCOC(=O)CC FKRCODPIKNYEAC-UHFFFAOYSA-N 0.000 claims description 12
- KMTRUDSVKNLOMY-UHFFFAOYSA-N Ethylene carbonate Chemical compound O=C1OCCO1 KMTRUDSVKNLOMY-UHFFFAOYSA-N 0.000 claims description 9
- 229910019142 PO4 Inorganic materials 0.000 claims description 9
- 229910052736 halogen Chemical group 0.000 claims description 9
- 150000002367 halogens Chemical group 0.000 claims description 9
- 239000010452 phosphate Substances 0.000 claims description 9
- 125000001424 substituent group Chemical group 0.000 claims description 9
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 8
- OBNCKNCVKJNDBV-UHFFFAOYSA-N ethyl butyrate Chemical compound CCCC(=O)OCC OBNCKNCVKJNDBV-UHFFFAOYSA-N 0.000 claims description 8
- RUOJZAUFBMNUDX-UHFFFAOYSA-N propylene carbonate Chemical compound CC1COC(=O)O1 RUOJZAUFBMNUDX-UHFFFAOYSA-N 0.000 claims description 7
- 239000002153 silicon-carbon composite material Substances 0.000 claims description 7
- 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 6
- YEJRWHAVMIAJKC-UHFFFAOYSA-N 4-Butyrolactone Chemical compound O=C1CCCO1 YEJRWHAVMIAJKC-UHFFFAOYSA-N 0.000 claims description 6
- YLQBMQCUIZJEEH-UHFFFAOYSA-N Furan Chemical group C=1C=COC=1 YLQBMQCUIZJEEH-UHFFFAOYSA-N 0.000 claims description 6
- YTPLMLYBLZKORZ-UHFFFAOYSA-N Thiophene Chemical group C=1C=CSC=1 YTPLMLYBLZKORZ-UHFFFAOYSA-N 0.000 claims description 6
- 229910021383 artificial graphite Inorganic materials 0.000 claims description 6
- 125000005842 heteroatom Chemical group 0.000 claims description 6
- 239000007773 negative electrode material Substances 0.000 claims description 6
- 150000003557 thiazoles Chemical class 0.000 claims description 6
- 125000002023 trifluoromethyl group Chemical group FC(F)(F)* 0.000 claims description 6
- OIFBSDVPJOWBCH-UHFFFAOYSA-N Diethyl carbonate Chemical compound CCOC(=O)OCC OIFBSDVPJOWBCH-UHFFFAOYSA-N 0.000 claims description 5
- 125000003118 aryl group Chemical group 0.000 claims description 5
- 125000004093 cyano group Chemical group *C#N 0.000 claims description 5
- JBTWLSYIZRCDFO-UHFFFAOYSA-N ethyl methyl carbonate Chemical compound CCOC(=O)OC JBTWLSYIZRCDFO-UHFFFAOYSA-N 0.000 claims description 5
- 229910001496 lithium tetrafluoroborate Inorganic materials 0.000 claims description 5
- IGILRSKEFZLPKG-UHFFFAOYSA-M lithium;difluorophosphinate Chemical compound [Li+].[O-]P(F)(F)=O IGILRSKEFZLPKG-UHFFFAOYSA-M 0.000 claims description 5
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 claims description 4
- IEJIGPNLZYLLBP-UHFFFAOYSA-N dimethyl carbonate Chemical compound COC(=O)OC IEJIGPNLZYLLBP-UHFFFAOYSA-N 0.000 claims description 4
- 229910021382 natural graphite Inorganic materials 0.000 claims description 4
- 125000006273 (C1-C3) alkyl group Chemical group 0.000 claims description 3
- 125000000217 alkyl group Chemical group 0.000 claims description 3
- 150000002148 esters Chemical group 0.000 claims description 3
- 125000000956 methoxy group Chemical group [H]C([H])([H])O* 0.000 claims description 3
- 125000002496 methyl group Chemical group [H]C([H])([H])* 0.000 claims description 3
- 125000004368 propenyl group Chemical group C(=CC)* 0.000 claims description 3
- 125000003107 substituted aryl group Chemical group 0.000 claims description 3
- 229930192474 thiophene Natural products 0.000 claims description 3
- 230000035939 shock Effects 0.000 abstract description 6
- 238000007600 charging Methods 0.000 description 11
- 238000012360 testing method Methods 0.000 description 10
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 9
- 229910001416 lithium ion Inorganic materials 0.000 description 9
- 230000000052 comparative effect Effects 0.000 description 8
- UHOVQNZJYSORNB-UHFFFAOYSA-N Benzene Chemical group C1=CC=CC=C1 UHOVQNZJYSORNB-UHFFFAOYSA-N 0.000 description 6
- 238000007599 discharging Methods 0.000 description 6
- 230000014759 maintenance of location Effects 0.000 description 6
- 238000006864 oxidative decomposition reaction Methods 0.000 description 5
- BTBUEUYNUDRHOZ-UHFFFAOYSA-N Borate Chemical compound [O-]B([O-])[O-] BTBUEUYNUDRHOZ-UHFFFAOYSA-N 0.000 description 4
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 4
- 239000013543 active substance Substances 0.000 description 4
- 239000007772 electrode material Substances 0.000 description 4
- 229910052739 hydrogen Inorganic materials 0.000 description 4
- 239000001257 hydrogen Substances 0.000 description 4
- 125000004435 hydrogen atom Chemical group [H]* 0.000 description 4
- 239000012528 membrane Substances 0.000 description 4
- 239000002245 particle Substances 0.000 description 4
- 238000011056 performance test Methods 0.000 description 4
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 description 4
- 230000009257 reactivity Effects 0.000 description 4
- XBDQKXXYIPTUBI-UHFFFAOYSA-M Propionate Chemical compound CCC([O-])=O XBDQKXXYIPTUBI-UHFFFAOYSA-M 0.000 description 3
- 238000010280 constant potential charging Methods 0.000 description 3
- 238000004090 dissolution Methods 0.000 description 3
- 238000006722 reduction reaction Methods 0.000 description 3
- 229910052723 transition metal Inorganic materials 0.000 description 3
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- 229910013716 LiNi Inorganic materials 0.000 description 2
- 239000002033 PVDF binder Substances 0.000 description 2
- 239000006230 acetylene black Substances 0.000 description 2
- 239000002253 acid Substances 0.000 description 2
- 230000009471 action Effects 0.000 description 2
- 239000010405 anode material Substances 0.000 description 2
- 239000010406 cathode material Substances 0.000 description 2
- 239000011248 coating agent Substances 0.000 description 2
- 238000000576 coating method Methods 0.000 description 2
- 230000007797 corrosion Effects 0.000 description 2
- 238000005260 corrosion Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000008151 electrolyte solution Substances 0.000 description 2
- 229910002804 graphite Inorganic materials 0.000 description 2
- 239000010439 graphite Substances 0.000 description 2
- VDVLPSWVDYJFRW-UHFFFAOYSA-N lithium;bis(fluorosulfonyl)azanide Chemical compound [Li+].FS(=O)(=O)[N-]S(F)(=O)=O VDVLPSWVDYJFRW-UHFFFAOYSA-N 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 125000004433 nitrogen atom Chemical group N* 0.000 description 2
- 229920002981 polyvinylidene fluoride Polymers 0.000 description 2
- 239000007774 positive electrode material Substances 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 230000001681 protective effect Effects 0.000 description 2
- 238000011084 recovery Methods 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 229920003048 styrene butadiene rubber Polymers 0.000 description 2
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical group [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 229910012851 LiCoO 2 Inorganic materials 0.000 description 1
- 229910015645 LiMn Inorganic materials 0.000 description 1
- 229910013290 LiNiO 2 Inorganic materials 0.000 description 1
- 229910013872 LiPF Inorganic materials 0.000 description 1
- 101150058243 Lipf gene Proteins 0.000 description 1
- 239000002174 Styrene-butadiene Substances 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical group [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 239000003125 aqueous solvent Substances 0.000 description 1
- 229910052786 argon Inorganic materials 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 210000004204 blood vessel Anatomy 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 239000011889 copper foil Substances 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 239000011888 foil Substances 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 229910000625 lithium cobalt oxide Inorganic materials 0.000 description 1
- BFZPBUKRYWOWDV-UHFFFAOYSA-N lithium;oxido(oxo)cobalt Chemical compound [Li+].[O-][Co]=O BFZPBUKRYWOWDV-UHFFFAOYSA-N 0.000 description 1
- 230000003446 memory effect Effects 0.000 description 1
- 239000011259 mixed solution Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
- 229910052720 vanadium Inorganic materials 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- 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
- H01M10/05—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
-
- 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
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Physics & Mathematics (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- General Physics & Mathematics (AREA)
- Inorganic Chemistry (AREA)
- Materials Engineering (AREA)
- Secondary Cells (AREA)
Abstract
The invention discloses an electrolyte and a battery, wherein the electrolyte comprises the following components: electrolyte salt, solvent, first additive and second additive, the structural formula of first additive is structural formula (1), the structural formula of second additive is structural formula (2). The first additive and the second additive are added into the electrolyte, so that the high-temperature storage performance of the battery can be improved, the dynamic performance can be considered, and the thermal shock performance can be improved.
Description
Technical Field
The invention belongs to the technical field of batteries, and particularly relates to electrolyte and a battery.
Background
The lithium ion battery is widely used by people due to the characteristics of high working voltage, large specific energy, long cycle life, no memory effect and the like, and is widely used in the field of digital consumer electronic products at present. With the advent of the 5G age, higher demands are put on the energy density of lithium ion batteries, and increasing the charge cutoff voltage of lithium ion batteries is one of the important means for increasing the energy density. The electrolyte plays a vital role as a blood vessel of the lithium ion battery, and under high voltage, the electrolyte can continuously undergo oxidative decomposition reaction on the surface of the electrode, so that the high-temperature storage performance of the battery is reduced.
Disclosure of Invention
The embodiment of the invention aims to provide an electrolyte and a battery, which are used for solving the problem of reduced high-temperature storage performance of the battery.
In a first aspect, an embodiment of the present invention provides an electrolyte, including:
electrolyte salt, solvent, first additive and second additive, the structural formula of the first additive is structural formula (1), the structural formula of the second additive is structural formula (2),
the structural formula (1) is as follows:
r1 is selected from a substituted or unsubstituted aryl or a five-membered ring containing a heteroatom, and in the case where R1 is a substituted aryl, the substituent in R1 is selected from alkyl, trifluoromethyl or halogen; in the case that R1 is a five-membered ring containing a heteroatom, the substituent in R1 is selected from thiophene, furan, substituted or unsubstituted thiazole, and the substituent of the substituted thiazole is halogen or methyl;
the structural formula (2) is as follows:
n1 is 0, 1, 2 or 3, n2 is 0, 1, 2 or 3, R2 and R3 are independently selected from propenyl, halogen, C1-C3 alkyl, methoxy, trifluoromethyl, ester, cyano or-SO 3 F。
Optionally, the first additive is selected from at least one of structural formulas (1-1) to (1-12), and structural formulas (1-1) to (1-12) are:
optionally, the second additive is selected from at least one of structural formulas (2-1) to (2-6), and structural formulas (2-1) to (2-6) are:
optionally, the mass content of the first additive accounts for 0.3-4% of the total mass of the electrolyte.
Optionally, the mass content of the second additive accounts for 0.3-4% of the total mass of the electrolyte.
Optionally, the mass content of the first additive is less than the mass content of the second additive.
Optionally, the electrolyte salt includes at least one of lithium hexafluorophosphate, lithium difluorophosphate, lithium difluorobis-oxalato phosphate, lithium tetrafluorooxalato phosphate, lithium bis-oxalato borate, lithium difluorooxalato borate, lithium tetrafluoroborate, lithium bis-trifluorosulfonimide, and lithium bis-fluorosulfonimide.
Optionally, the mass content of the electrolyte salt accounts for 10-20% of the total mass of the electrolyte.
Optionally, the solvent includes at least one of ethylene carbonate, propylene carbonate, diethyl carbonate, methylethyl carbonate, dimethyl carbonate, ethyl propionate, propyl propionate, ethyl acetate, ethyl n-butyrate, and gamma-butyrolactone.
In a second aspect, an embodiment of the present invention provides a battery including:
the electrolyte described in the above examples.
Optionally, the battery further comprises:
the negative electrode plate comprises a negative electrode active material, wherein the negative electrode active material comprises at least one of artificial graphite, natural graphite, lithium titanate and silicon-carbon composite material.
The electrolyte of the embodiment of the invention comprises the following components: electrolyte salt, solvent, first additive and second additive, the structural formula of the first additive is structural formula (1), the structural formula of the second additive is structural formula (2), the lone electron pair and ortho-connected aromatic ring (such as benzene ring) on N atom in the structure of the first additive enable the first additive to have higher electron cloud density, a small amount of the first additive can show stronger Lewis basicity when being added into electrolyte, and the first additive can be matched with PF in the electrolyte 5 Formation of the formulationA compound to reduce the acidity and reactivity of the electrolyte to inhibit the increase in free acid of the electrolyte; the cyano group can be complexed with lithium cobaltate to inhibit the surface reactivity of the electrode, reduce the oxidative decomposition of electrolyte at high temperature, and effectively inhibit the thickness expansion of high-temperature storage; the first additive is easily oxidized and decomposed on the surface of the positive electrode in the electrolyte to form an interfacial film. The second additive can form a layer of uniform and compact protective film on the surface of the electrode material, thereby reducing the Li of the positive electrode + The non-uniform embedding phenomenon is inhibited, meanwhile, the corrosion of HF to LCO particles is inhibited, the generation of cracks in the LCO particles in the circulation process is avoided, the dissolution of transition metal elements at high temperature is reduced, and meanwhile, the additive can be reduced on the surface of a cathode material (the reduction potential is 1.5V vs Li + Li) to form compact stable SEI film, and reduce the oxidative decomposition of electrolyte on the surface of the anode material. The first additive and the second additive are added into the electrolyte, so that the high-temperature storage performance of the battery can be improved, the dynamic performance can be considered, and the thermal shock performance can be improved.
Detailed Description
The technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
The terms first, second and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used may be interchanged where appropriate such that embodiments of the invention may be practiced otherwise than as described herein. Furthermore, in the description and claims, "and/or" means at least one of the connected objects, and the character "/", generally means that the associated object is an "or" relationship.
The electrolyte of the embodiment of the invention comprises the following components: electrolyte salt, solvent, first additive and second additive, the structural formula of first additive is structural formula (1), the structural formula of second additive is structural formula (2), structural formula (1) is:
r1 is selected from a substituted or unsubstituted aryl or a five-membered ring containing a heteroatom, and in the case where R1 is a substituted aryl, the substituent in R1 is selected from alkyl, trifluoromethyl or halogen; in the case that R1 is a five-membered ring containing a heteroatom, the substituent in R1 is selected from thiophene, furan, substituted or unsubstituted thiazole, and the substituent of the substituted thiazole is halogen or methyl;
the structural formula (2) is as follows:
n1 is 0, 1, 2 or 3, n2 is 0, 1, 2 or 3, R2 and R3 are independently selected from propenyl, halogen, C1-C3 alkyl, methoxy, trifluoromethyl, ester, cyano or-SO 3 F。
n1 represents zero hydrogen on the ring substituted by R2 when it is 0, one hydrogen on the ring substituted by R2 when it is 1, two hydrogens on the ring substituted by R2 when it is 2, and three hydrogens on the ring substituted by R2 when it is 3; n2 represents zero hydrogen on the ring substituted by R3 when it is 0, one hydrogen on the ring substituted by R3 when it is 1, two hydrogens on the ring substituted by R3 when it is 2, and three hydrogens on the ring substituted by R3 when it is 3.
The electrolyte salt may include at least one of lithium hexafluorophosphate, lithium difluorophosphate, lithium difluorobisoxalato phosphate, lithium tetrafluorooxalato phosphate, lithium bisoxalato borate, lithium difluorooxalato borate, lithium tetrafluoroborate, and lithium difluorosulfonimide. For example, the electrolyte salt may be lithium hexafluorophosphate, and the electrolyte salt may include lithium hexafluorophosphate, lithium tetrafluoroborate. The solvent may include at least one of ethylene carbonate, propylene carbonate, diethyl carbonate, methyl ethyl carbonate, dimethyl carbonate, ethyl propionate, propyl propionate, ethyl acetate, and ethyl n-butyrate. For example, the solvent may include ethylene carbonate, ethyl propionate, ethyl acetate. The specific types and types of the electrolyte salt and the solvent can be reasonably selected according to actual needs.
The electrolyte of the embodiment of the invention comprises the following components: electrolyte salt, solvent, first additive and second additive, the structural formula of the first additive is structural formula (1), the structural formula of the second additive is structural formula (2), the lone electron pair and ortho-connected aromatic ring (such as benzene ring) on N atom in the structure of the first additive enable the first additive to have higher electron cloud density, a small amount of the first additive can show stronger Lewis basicity when being added into electrolyte, and the first additive can be matched with PF in the electrolyte 5 Forming a complex, thereby reducing the acidity and reactivity of the electrolyte to inhibit the increase of the free acid of the electrolyte; the cyano group can be complexed with lithium cobaltate to inhibit the surface reactivity of the electrode, reduce the oxidative decomposition of electrolyte at high temperature, and effectively inhibit the thickness expansion of high-temperature storage; the first additive is easily oxidized and decomposed on the surface of the positive electrode in the electrolyte to form an interfacial film. The second additive can form a layer of uniform and compact protective film on the surface of the electrode material, thereby reducing the Li of the positive electrode + The non-uniform embedding phenomenon is inhibited, meanwhile, the corrosion of HF to LCO particles is inhibited, the generation of cracks in the LCO particles in the circulation process is avoided, the dissolution of transition metal elements at high temperature is reduced, and meanwhile, the additive can be reduced on the surface of a cathode material (the reduction potential is 1.5V vs Li + Li) to form compact stable SEI film, and reduce the oxidative decomposition of electrolyte on the surface of the anode material. The first additive and the second additive are added into the electrolyte, so that the high-temperature storage performance of the battery can be improved, the dynamic performance can be considered, and the thermal shock performance can be improved. Therefore, through the combined action of the first additive and the second additive, the film can be formed on the surface of the positive electrode, the direct contact of the electrode material and the electrolyte is avoided, the microstructure of the electrode material is stabilized, the dissolution of transition metal elements at high temperature is reduced, an SEI film can be formed on the surface of the negative electrode material, the reduction reaction of a solvent at the interface of the negative electrode is inhibited, and the high-temperature storage performance of the battery at high voltage can be effectively improvedThe low temperature performance of the battery can also be improved by the additives.
In some embodiments, the first additive may be selected from at least one of structural formulas (1-1) to (1-12), structural formulas (1-1) to (1-12) being:
for example, the first additive may be selected from one of the structural formulae (1-1) to (1-12), the first additive may be selected from the structural formulae (1-1) and (1-6), the first additive may be selected from the structural formulae (1-10) and (1-12), and the first additive may be selected from different structural formulae according to the actual fact. The first additives can be selected from different structural formulas at the same time, and the first additives with a plurality of different structural formulas are matched for use, so that the effect is enhanced, and the battery performance is improved.
In some embodiments, the second additive is selected from at least one of formulas (2-1) to (2-6), formulas (2-1) to (2-6) being:
for example, the second additive may be selected from one of the structural formulas (2-1) to (2-6), the second additive may be selected from the structural formulas (2-1) and (2-3), the second additive may be selected from the structural formulas (2-1) and (2-4), the second additive may be selected from the structural formulas (2-1) and (2-6), and the second additive may be actually selected from different structural formulas. The second additive can be simultaneously selected from different structural formulas, and the first additive with a plurality of different structural formulas is matched for use, so that the effect is enhanced, and the battery performance is improved.
In an embodiment of the present invention, the mass content of the first additive may be 0.3 to 4% of the total mass of the electrolyte. For example, the mass content of the first additive may be 0.3%, 1%, 2% or 4% of the total mass of the electrolyte, and the mass content of the first additive may be selected according to practice.
Optionally, the mass content of the second additive accounts for 0.3-4% of the total mass of the electrolyte. For example, the mass content of the second additive may be 0.3%, 1%, 2% or 4% of the total mass of the electrolyte, and the mass content of the second additive may be selected according to practice.
Optionally, the mass content of the first additive is less than the mass content of the second additive. For example, the first additive may comprise 1% by mass of the total mass of the electrolyte and the second additive may comprise 1.5% by mass of the total mass of the electrolyte; the first additive may be present in an amount of 2% by mass of the total mass of the electrolyte and the second additive may be present in an amount of 4% by mass of the total mass of the electrolyte.
Alternatively, the electrolyte salt may include at least one of lithium hexafluorophosphate, lithium difluorophosphate, lithium difluorobis-oxalato-phosphate, lithium tetrafluorooxalato-phosphate, lithium bis-oxalato-borate, lithium difluorooxalato-borate, lithium tetrafluoroborate, lithium bis-trifluorosulfonimide, and lithium bis-fluorosulfonimide. For example, the electrolyte salt may be lithium hexafluorophosphate, the electrolyte salt may include lithium hexafluorophosphate, lithium difluorophosphate, lithium difluorosulfonimide, and the specific kind and content of the electrolyte salt may be selected according to the practice.
Alternatively, the mass content of the electrolyte salt may be 10 to 20% of the total mass of the electrolyte solution. For example, the mass content of the electrolyte salt may be 10%, 15% or 20% of the total mass of the electrolyte solution, and the specific content of the electrolyte salt may be selected according to the actual use.
Alternatively, the solvent may be a non-aqueous solvent, and the solvent may include at least one of ethylene carbonate, propylene carbonate, diethyl carbonate, ethylmethyl carbonate, dimethyl carbonate, ethyl propionate, propyl propionate, ethyl acetate, ethyl n-butyrate, and gamma-butyrolactone. For example, the solvent may include ethylene carbonate, diethyl carbonate, ethyl propionate, and the solvent may include methylethyl carbonate, propyl propionate, ethyl acetate, and the specific kind and content of the solvent may be selected according to practice.
The battery of the embodiment of the invention comprises:
the electrolyte described in the above examples. The battery with the electrolyte in the embodiment can improve the high-temperature storage performance of the battery, can give consideration to the dynamic performance and improves the thermal shock performance.
In some embodiments, the battery may further include:
the negative electrode plate can comprise a negative electrode active substance, the negative electrode active substance can comprise at least one of artificial graphite, natural graphite, lithium titanate and a silicon-carbon composite material, and the silicon-carbon composite material can be prepared from SiO w The silicon-carbon composite material compounded with graphite is more than 1 and less than 2, for example, the negative electrode active material can be artificial graphite or silicon-carbon composite material.
The battery can be a lithium ion battery, the battery can comprise a positive plate, a negative plate, a diaphragm arranged between the positive plate and the negative plate at intervals and electrolyte, the electrolyte is the electrolyte, and the charge cut-off voltage of the lithium ion battery can be greater than or equal to 4.2V.
The positive plate comprises a positive current collector and a positive membrane, the positive membrane comprises a positive active material, and the positive active material is LiCoO 2 、LiNiO 2 、LiCoyM 1-y O 2 、LiNi y M 1-y O 2 、LiMn y M 1-y O 2 、LiNi 1-x-y-z Co x Mn y M z O 2 Wherein M may be selected from one or more of Fe, co, ni, mn, mg, cu, zn, al, sn, B, ga, cr, sr, V, ti, 0.ltoreq.x.ltoreq.1, 0.ltoreq.y.ltoreq.1, 0.ltoreq.z.ltoreq.1 and 0.ltoreq.x+y+z.ltoreq.1; the negative electrode sheet comprises a negative electrode current collector and a negative electrode membrane, the negative electrode membrane comprises a negative electrode active substance, and the negative electrode active substance can be artificial graphite, natural graphite, lithium titanate or SiO w The silicon-carbon composite material compounded with graphite has w more than 1 and less than 2.
The invention is further illustrated by the following examples.
Example 1
In a glove box filled with argon, the oxygen content is less than or equal to 1ppm, the water content is less than or equal to 1ppm, ethylene Carbonate (EC), propylene Carbonate (PC) and Propyl Propionate (PP) are mixed according to the mass ratio EC: PC: pp=2:1:7, and then 12.5% of lithium hexafluorophosphate (LiPF) based on the total weight of the electrolyte is slowly added into the mixed solution 6 ) And finally, adding 1.0% of a first additive and 1.5% of a second additive based on the total weight of the electrolyte, and uniformly stirring to obtain the lithium ion battery electrolyte of the embodiment 1.
Example 2-example 25
Examples 2-25, comparative examples 1-3 differ from example 1 in the types and amounts of the first additive and the second additive in the electrolyte, and can be seen in Table 1.
Example 26-example 28
Examples 26 to 28 differ from example 1 in the type and amount of electrolyte salts in the electrolyte, and examples 26 to 28 show the types and amounts of the first additive and the second additive, as shown in Table 1.
The electrolyte salt in example 26 was lithium hexafluorophosphate, the content of which was 10% of the total weight of the electrolyte;
the electrolyte salt in example 27 was lithium hexafluorophosphate, the content of which was 20% of the total weight of the electrolyte;
the electrolyte salt in the embodiment 28 is lithium bis (fluorosulfonyl) imide, and the content of the lithium bis (fluorosulfonyl) imide is 12.5% of the total weight of the electrolyte;
TABLE 1 example 1-example 28 types and contents of additives in electrolytes
1. Assembling a lithium ion battery: the electrolytes of examples 1 to 28 and comparative examples 1 to 3 described above were respectively used as electrolytes of lithium ion batteries, assembled into a pouch-type battery, in which,
a diaphragm: a PP separator;
positive pole piece: the positive electrode current collector is aluminum foil, and the positive electrode coating consists of lithium cobalt oxide, acetylene black and polyvinylidene fluoride PVDF in a mass ratio of 95:3:2;
negative pole piece: the negative electrode current collector is copper foil, and the negative electrode coating consists of artificial graphite, acetylene black and styrene butadiene rubber SBR in a mass ratio of 94:3:3.
After the positive electrode sheet, the negative electrode sheet and the PP separator are sequentially overlapped, the electrolytes prepared in examples 1-28 and comparative examples 1-3 are respectively added to assemble soft-packed batteries, which are respectively marked as test batteries 1-28 and comparative batteries 1-3.
2. Electrochemical performance test: the blue electric charge and discharge test cabinet is adopted to test the electrochemical performance by the following test method:
(1) High temperature cycle performance test
High temperature cycle performance test: at 45 ℃, charging the separated battery to 4.45V according to a constant current and a constant voltage of 0.7C, cutting off the current to 0.05C, discharging to 3.0V according to a constant current of 0.5C, and calculating the capacity retention rate at 300 weeks after 300 times of charging and discharging according to the circulation, wherein the calculation formula is as follows:
cycle capacity retention at 300 weeks (%) = (cycle discharge capacity at 300 weeks/first cycle discharge capacity) ×100%.
(2) 60 ℃ 14d high temperature storage test
Charging and discharging the battery at normal temperature for 1 time (4.45V-3.0V) at 0.5C, recording the discharge capacity C0 before the battery is stored, then charging the battery to 4.50V full state at constant current and constant voltage, testing the thickness d1 of the battery before the high-temperature storage (two diagonal lines of the battery are respectively connected through a straight line, and the intersection point of the two diagonal lines is a battery thickness test point) by using a vernier caliper, placing the battery into a 60 ℃ incubator for storage for 14 days, taking out the battery after the storage is completed, testing the thermal thickness d2 of the battery after the storage, and calculating the thickness expansion rate of the battery after the battery is stored at 60 ℃ for 14 days; after the battery is cooled for 24 hours at room temperature, the battery is discharged to 3.0V at a constant current of 0.5C, then the battery is charged to 4.45V at a constant current and constant voltage of 0.5C, the discharge capacity C1 and the charge capacity C2 of the battery after storage are recorded, the capacity remaining rate and the recovery rate of the battery after storage at 60 ℃ for 14 days are calculated, and the calculation formula is as follows:
thickness expansion ratio = (d 2-d 1)/d 1 x 100% after 14 days of storage at 60 ℃;
residual capacity retention = C1/C0 x 100% after 14 days storage at 60 ℃;
recovery capacity retention = C2/C0 x 100% after 14 days storage at 60 ℃.
(3) Low temperature discharge performance test
Discharging the battery with the capacity of 0.5C to 3.0V at the temperature of 25 ℃ and standing for 5min; charging to 4.45V at 0.2C, changing to 4.45V constant voltage charging when the voltage of the battery cell reaches 4.45V until the charging current is less than or equal to the given cutoff current of 0.05C, and standing for 5min; transferring the fully charged core into a high-low temperature box, setting the temperature to-10 ℃, and standing for 120min after the temperature of the box reaches; then discharging at 0.2C to a final voltage of 3.0V, and standing for 5min; then the temperature of the high-low temperature box is adjusted to 25+/-3 ℃, and the box is left for 60 minutes after the temperature of the box is reached; charging the battery to 4.45V at 0.2C, and changing the battery to 4.45V constant voltage charging when the voltage of the battery cell reaches 4.45V until the charging current is less than or equal to the given cutoff current of 0.05C; standing for 5min; the capacity retention rate of 3.0V discharge at-10 ℃ is calculated. The calculation formula is as follows:
-10 ℃ discharge 3.0V capacity retention (%) = (-10 ℃ discharge to 3.0V discharge capacity/25 ℃ discharge to 3.0V discharge capacity) ×100%.
(4) Thermal shock property
Discharging to 3.0V at a given current of 0.2C under ambient conditions of 25 ℃; standing for 5min; charging to 4.45V at a charging current of 0.2C, and changing to 4.45V constant voltage charging when the voltage of the battery cell reaches 4.45V until the charging current is less than or equal to a given cutoff current of 0.05C; placing the battery cell into an oven after the battery cell is placed for 1h, and raising the temperature of the oven to 135+/-2 ℃ at the speed of 5+/-2 ℃/min, and stopping after the battery cell is kept for 30min, wherein the judgment standard is that the battery cell does not fire or explode.
Table 2 battery test results for examples 1-28 and comparative examples 1-3
From comparison of the test results of comparative examples 1 to 3 and examples 1 to 28 in Table 2, it is clear that:
the test results of the electrolyte batteries in the comparative example and the example show that, compared with the comparative example, the interface protection film can be formed on the positive and negative surfaces by the combined action of the first additive and the second additive in the example, which is favorable for improving the interface stability of the battery, further improving the high-temperature storage performance, the cycle performance and the thermal shock performance of the battery under high voltage, and further improving the low-temperature performance of the battery by the additive.
While the present invention has been described with reference to the above-described embodiments, it is to be understood that the same is not limited to the above-described embodiments, but rather that the same is intended to be illustrative only, and that many modifications may be made by one of ordinary skill in the art without departing from the spirit of the invention and scope of the appended claims.
Claims (10)
1. An electrolyte, comprising:
electrolyte salt, solvent, first additive and second additive, the structural formula of the first additive is structural formula (1), the structural formula of the second additive is structural formula (2),
the structural formula (1) is as follows:
r1 is selected from a substituted or unsubstituted aryl or a five-membered ring containing a heteroatom, and in the case where R1 is a substituted aryl, the substituent in R1 is selected from alkyl, trifluoromethyl or halogen; in the case that R1 is a five-membered ring containing a heteroatom, the substituent in R1 is selected from thiophene, furan, substituted or unsubstituted thiazole, and the substituent of the substituted thiazole is halogen or methyl;
the structural formula (2) is as follows:
n1 is 0, 1, 2 or 3, n2 is 0, 1, 2 or 3, R2 and R3 are independently selected from propenyl, halogen, C1-C3 alkyl, methoxy, trifluoromethyl, ester, cyano or-SO 3 F。
2. The electrolyte of claim 1, wherein the first additive is selected from at least one of structural formulas (1-1) to (1-12), structural formulas (1-1) to (1-12) being:
3. the electrolyte of claim 1, wherein the second additive is selected from at least one of structural formulas (2-1) to (2-6), structural formulas (2-1) to (2-6) being:
4. the electrolyte according to any one of claims 1 to 3, wherein the mass content of the first additive is 0.3 to 4% of the total mass of the electrolyte.
5. The electrolyte according to any one of claims 1 to 3, wherein the mass content of the second additive is 0.3 to 4% of the total mass of the electrolyte.
6. The electrolyte of claim 1, wherein the electrolyte salt comprises at least one of lithium hexafluorophosphate, lithium difluorophosphate, lithium difluorobis-oxalato-phosphate, lithium tetrafluorooxalato-phosphate, lithium oxalato-phosphate, lithium bis-oxalato-borate, lithium difluorooxalato-borate, lithium tetrafluoroborate, lithium bis-trifluorosulfonimide, and lithium bis-fluorosulfonimide.
7. The electrolyte according to claim 1, wherein the mass content of the electrolyte salt is 10 to 20% of the total mass of the electrolyte.
8. The electrolyte of claim 1, wherein the solvent comprises at least one of ethylene carbonate, propylene carbonate, diethyl carbonate, ethylmethyl carbonate, dimethyl carbonate, ethyl propionate, propyl propionate, ethyl acetate, ethyl n-butyrate, and gamma-butyrolactone.
9. A battery, comprising:
the electrolyte of any one of claims 1-8.
10. The battery of claim 9, further comprising:
the negative electrode plate comprises a negative electrode active material, wherein the negative electrode active material comprises at least one of artificial graphite, natural graphite, lithium titanate and silicon-carbon composite material.
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