CN117638231A - Lithium ion battery quick-charge electrolyte, preparation method and lithium ion battery - Google Patents
Lithium ion battery quick-charge electrolyte, preparation method and lithium ion battery Download PDFInfo
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- CN117638231A CN117638231A CN202311637411.7A CN202311637411A CN117638231A CN 117638231 A CN117638231 A CN 117638231A CN 202311637411 A CN202311637411 A CN 202311637411A CN 117638231 A CN117638231 A CN 117638231A
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- 239000003792 electrolyte Substances 0.000 title claims abstract description 122
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 title claims abstract description 44
- 229910001416 lithium ion Inorganic materials 0.000 title claims abstract description 44
- 238000002360 preparation method Methods 0.000 title abstract description 5
- 229910003002 lithium salt Inorganic materials 0.000 claims abstract description 32
- 159000000002 lithium salts Chemical class 0.000 claims abstract description 32
- 239000000654 additive Substances 0.000 claims abstract description 22
- -1 fluoro carboxylic ester Chemical class 0.000 claims abstract description 15
- 230000000996 additive effect Effects 0.000 claims abstract description 11
- 239000003960 organic solvent Substances 0.000 claims abstract description 8
- 238000000034 method Methods 0.000 claims abstract description 4
- 239000002904 solvent Substances 0.000 claims abstract description 4
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical group [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 40
- 229910002804 graphite Inorganic materials 0.000 claims description 40
- 239000010439 graphite Substances 0.000 claims description 40
- 150000002148 esters Chemical class 0.000 claims description 17
- 229910052744 lithium Inorganic materials 0.000 claims description 14
- SBLRHMKNNHXPHG-UHFFFAOYSA-N 4-fluoro-1,3-dioxolan-2-one Chemical compound FC1COC(=O)O1 SBLRHMKNNHXPHG-UHFFFAOYSA-N 0.000 claims description 11
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 claims description 11
- 125000001153 fluoro group Chemical group F* 0.000 claims description 10
- ZPFAVCIQZKRBGF-UHFFFAOYSA-N 1,3,2-dioxathiolane 2,2-dioxide Chemical compound O=S1(=O)OCCO1 ZPFAVCIQZKRBGF-UHFFFAOYSA-N 0.000 claims description 7
- WDXYVJKNSMILOQ-UHFFFAOYSA-N 1,3,2-dioxathiolane 2-oxide Chemical compound O=S1OCCO1 WDXYVJKNSMILOQ-UHFFFAOYSA-N 0.000 claims description 6
- 125000000217 alkyl group Chemical group 0.000 claims description 6
- KMTRUDSVKNLOMY-UHFFFAOYSA-N Ethylene carbonate Chemical compound O=C1OCCO1 KMTRUDSVKNLOMY-UHFFFAOYSA-N 0.000 claims description 5
- 238000006467 substitution reaction Methods 0.000 claims description 5
- FSSPGSAQUIYDCN-UHFFFAOYSA-N 1,3-Propane sultone Chemical compound O=S1(=O)CCCO1 FSSPGSAQUIYDCN-UHFFFAOYSA-N 0.000 claims description 4
- BTBUEUYNUDRHOZ-UHFFFAOYSA-N Borate Chemical compound [O-]B([O-])[O-] BTBUEUYNUDRHOZ-UHFFFAOYSA-N 0.000 claims description 4
- 239000002253 acid Substances 0.000 claims description 4
- 239000011149 active material Substances 0.000 claims description 4
- 239000000463 material Substances 0.000 claims description 4
- BTGRAWJCKBQKAO-UHFFFAOYSA-N adiponitrile Chemical compound N#CCCCCC#N BTGRAWJCKBQKAO-UHFFFAOYSA-N 0.000 claims description 3
- IGILRSKEFZLPKG-UHFFFAOYSA-M lithium;difluorophosphinate Chemical compound [Li+].[O-]P(F)(F)=O IGILRSKEFZLPKG-UHFFFAOYSA-M 0.000 claims description 3
- IAHFWCOBPZCAEA-UHFFFAOYSA-N succinonitrile Chemical compound N#CCCC#N IAHFWCOBPZCAEA-UHFFFAOYSA-N 0.000 claims description 3
- 229910013716 LiNi Inorganic materials 0.000 claims description 2
- 125000004432 carbon atom Chemical group C* 0.000 claims description 2
- 229910052731 fluorine Inorganic materials 0.000 claims description 2
- GQJCAQADCPTHKN-UHFFFAOYSA-N methyl 2,2-difluoro-2-fluorosulfonylacetate Chemical compound COC(=O)C(F)(F)S(F)(=O)=O GQJCAQADCPTHKN-UHFFFAOYSA-N 0.000 claims description 2
- 239000007773 negative electrode material Substances 0.000 claims description 2
- 239000007774 positive electrode material Substances 0.000 claims description 2
- 150000001875 compounds Chemical class 0.000 abstract description 2
- 238000013508 migration Methods 0.000 abstract description 2
- 230000005012 migration Effects 0.000 abstract description 2
- 230000000052 comparative effect Effects 0.000 description 20
- VCYZVXRKYPKDQB-UHFFFAOYSA-N ethyl 2-fluoroacetate Chemical compound CCOC(=O)CF VCYZVXRKYPKDQB-UHFFFAOYSA-N 0.000 description 18
- 230000014759 maintenance of location Effects 0.000 description 12
- VDVLPSWVDYJFRW-UHFFFAOYSA-N lithium;bis(fluorosulfonyl)azanide Chemical compound [Li+].FS(=O)(=O)[N-]S(F)(=O)=O VDVLPSWVDYJFRW-UHFFFAOYSA-N 0.000 description 6
- ZJPPTKRSFKBZMD-UHFFFAOYSA-N [Li].FS(=N)F Chemical compound [Li].FS(=N)F ZJPPTKRSFKBZMD-UHFFFAOYSA-N 0.000 description 5
- 238000012360 testing method Methods 0.000 description 5
- IEJIGPNLZYLLBP-UHFFFAOYSA-N dimethyl carbonate Chemical compound COC(=O)OC IEJIGPNLZYLLBP-UHFFFAOYSA-N 0.000 description 4
- 239000012046 mixed solvent Substances 0.000 description 4
- 238000005520 cutting process Methods 0.000 description 3
- 230000001351 cycling effect Effects 0.000 description 3
- GZKHDVAKKLTJPO-UHFFFAOYSA-N ethyl 2,2-difluoroacetate Chemical compound CCOC(=O)C(F)F GZKHDVAKKLTJPO-UHFFFAOYSA-N 0.000 description 3
- CSSYKHYGURSRAZ-UHFFFAOYSA-N methyl 2,2-difluoroacetate Chemical compound COC(=O)C(F)F CSSYKHYGURSRAZ-UHFFFAOYSA-N 0.000 description 3
- 238000002156 mixing Methods 0.000 description 3
- 238000004080 punching Methods 0.000 description 3
- OIFBSDVPJOWBCH-UHFFFAOYSA-N Diethyl carbonate Chemical compound CCOC(=O)OCC OIFBSDVPJOWBCH-UHFFFAOYSA-N 0.000 description 2
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 description 2
- 239000011230 binding agent Substances 0.000 description 2
- 150000001733 carboxylic acid esters Chemical class 0.000 description 2
- 239000011248 coating agent Substances 0.000 description 2
- 238000000576 coating method Methods 0.000 description 2
- 238000001035 drying Methods 0.000 description 2
- 239000008151 electrolyte solution Substances 0.000 description 2
- DBOFMRQAMAZKQY-UHFFFAOYSA-N ethyl 2,2,3,3,3-pentafluoropropanoate Chemical compound CCOC(=O)C(F)(F)C(F)(F)F DBOFMRQAMAZKQY-UHFFFAOYSA-N 0.000 description 2
- QSZMZKBZAYQGRS-UHFFFAOYSA-N lithium;bis(trifluoromethylsulfonyl)azanide Chemical compound [Li+].FC(F)(F)S(=O)(=O)[N-]S(=O)(=O)C(F)(F)F QSZMZKBZAYQGRS-UHFFFAOYSA-N 0.000 description 2
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 2
- 238000005096 rolling process Methods 0.000 description 2
- 239000002002 slurry Substances 0.000 description 2
- 239000000243 solution Substances 0.000 description 2
- 238000003756 stirring Methods 0.000 description 2
- VAYTZRYEBVHVLE-UHFFFAOYSA-N 1,3-dioxol-2-one Chemical compound O=C1OC=CO1 VAYTZRYEBVHVLE-UHFFFAOYSA-N 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 239000002033 PVDF binder Substances 0.000 description 1
- 239000004698 Polyethylene Substances 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000033228 biological regulation Effects 0.000 description 1
- 238000013329 compounding Methods 0.000 description 1
- 239000011889 copper foil Substances 0.000 description 1
- 239000006184 cosolvent Substances 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- VEWLDLAARDMXSB-UHFFFAOYSA-N ethenyl sulfate;hydron Chemical compound OS(=O)(=O)OC=C VEWLDLAARDMXSB-UHFFFAOYSA-N 0.000 description 1
- 239000011888 foil Substances 0.000 description 1
- 239000012528 membrane Substances 0.000 description 1
- 239000002931 mesocarbon microbead Substances 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000004806 packaging method and process Methods 0.000 description 1
- 229920000573 polyethylene Polymers 0.000 description 1
- 229920002981 polyvinylidene fluoride Polymers 0.000 description 1
- 239000002356 single layer Substances 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- 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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- Secondary Cells (AREA)
Abstract
The invention relates to the field of batteries, in particular to a lithium ion battery quick-charge electrolyte, a preparation method and a lithium ion battery. The lithium ion battery fast-charging electrolyte comprises: an organic solvent, a lithium salt, and an additive; wherein the organic solvent is fluoro carboxylic ester. The fluorocarboxylate compound is used as a solvent of a lithium ion battery quick-charge electrolyte, and can effectively improve the voltage resistance of the electrolyte and the dynamic migration process of lithium ions.
Description
Technical Field
The invention relates to the field of batteries, in particular to a lithium ion battery quick-charge electrolyte, a preparation method and a lithium ion battery.
Background
In recent years, lithium ion batteries promote the rapid development of electric vehicles, so that the endurance mileage of the electric vehicles basically meets the travel demands of people, but still faces the problem of long charging time. However, since the dynamic performance of lithium ions migrating in commercial electrolyte is poor and the corresponding interface impedance is large, the good rate performance cannot be realized, and a large gap exists between the realization of 'extremely fast charging'.
By adding a small amount of additive into the mature commercial electrolyte, the regulation and control of the interface are realized, the interface impedance is reduced, and the rate capability of the battery is further improved. At present, no ideal practical electrolyte can realize stable circulation of the lithium ion battery at a higher multiplying power.
Disclosure of Invention
In order to solve the technical problems, the invention provides a lithium ion battery quick-charge electrolyte, which comprises the following components: organic solvents, lithium salts and additives; wherein the organic solvent is fluoro carboxylic ester.
Further, the general formula of the fluorocarboxylic acid ester isThe R is 1 And R is 2 Is an alkyl chain having 1 to 3 carbon atoms, and at least one of the alkyl chains contains a fluorine atom.
Further, the specific structural formula of the fluorocarboxylic acid ester comprises
At least one of them.
Further, the additive is at least two of fluoroethylene carbonate, 1, 3-propane sultone, vinylene carbonate, lithium difluorophosphate, methyl fluorosulfonyl difluoroacetate, ethylene sulfate, ethylene sulfite, adiponitrile and succinonitrile.
Further, the lithium salt is at least one of lithium hexafluorophosphate, lithium bis (fluorosulfonyl) imide, lithium bis (trifluoromethylsulfonyl) imide, lithium difluorooxalato borate and lithium dioxaato borate.
Further, the lithium salt accounts for 10-30% of the mass fraction of the lithium ion battery quick-charge electrolyte, and the additive accounts for 5-10% of the mass fraction of the lithium ion battery quick-charge electrolyte.
Further, when R of the fluorocarboxylic acid ester 1 And R is 2 In the alkyl chain of (2), the solubility of the fluorine atoms to lithium salt is better when the substitution degree of the fluorine atoms is not more than half of the number, and the solubility of the fluorine atoms to lithium salt is poorer when the substitution degree of the fluorine atoms is more than half of the number, so that the fluorine atoms can be used as a main solvent, and the fluorine atoms are required to be used as a cosolvent in a compounding way with the fluorinated carboxylic ester with low substitution degree.
Also provided is a method for preparing the lithium ion battery quick-charge electrolyte, which comprises the step of mixing the organic solvent, the lithium salt and the additive.
The lithium ion battery comprises the lithium ion battery fast-charging electrolyte.
Further, the battery also comprises a positive electrode and a negative electrode, wherein the active material in the positive electrode is NCM ternary material; preferably, the NCM ternary material is LiNi x Mn y Co z O 2 Wherein x+y+z=1, and 0<x,y,z<1。
Further, the active material in the negative electrode is graphite.
Further, the positive and negative electrode active materials have a surface capacity of 0.5 to 3.5mAh cm -2 。
Compared with the prior art, the invention has the following beneficial effects:
(1) The fluorocarboxylate compound is used as a solvent for fast charging electrolyte of a lithium ion battery, and can effectively improve the voltage resistance of the electrolyte and the dynamic migration process of lithium ions.
(2) The lithium salt, the fluorinated carboxylic ester and the additive in the quick-charging electrolyte for the high-voltage lithium ion battery are specifically combined, and the concentration and the proportion are further optimized, so that the high-voltage electrolyte added by the invention has excellent compatibility with the anode and the cathode and good compatibility and multiplying power performance with a graphite anode.
(3) The high-voltage electrolyte for the lithium ion battery belongs to an electrolyte system with high ionic conductivity, wide electrochemical window, good film forming performance and excellent multiplying power performance, and has wide application prospect in the high-voltage lithium ion quick-charging battery.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.
Drawings
The accompanying drawings are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate and do not limit the invention.
Fig. 1 is a ratio-cycle specific capacity-voltage curve of the electrolyte prepared in example 1 in li|graphite half-cells.
Fig. 2 is a ratio-cycle specific capacity-voltage curve of the electrolyte prepared in example 2 in li|graphite half-cells.
Fig. 3 is a ratio-cycle specific capacity-voltage curve of the electrolyte prepared in example 3 in li|graphite half-cells.
Fig. 4 is a ratio cycling specific capacity-voltage curve of the electrolyte prepared in example 4 in NCM811 graphite soft pack full cell.
Fig. 5 is a discharge capacity-coulombic efficiency result of the electrolyte prepared in example 5 for a long cycle in a li|graphite half-cell.
Fig. 6 is a discharge capacity-coulombic efficiency result of the electrolyte prepared in example 6 for a long cycle in NCM811 graphite full cell.
Fig. 7 is a discharge capacity-coulombic efficiency result of the electrolyte prepared in example 7 for a long cycle in NCM811 graphite full cell.
Fig. 8 is a ratio-cycle specific capacity-voltage curve of the commercial ester-based electrolyte prepared in comparative example 1 in li|graphite half-cells.
Fig. 9 is a discharge capacity-coulombic efficiency result of the commercial ester-based electrolyte prepared in comparative example 2 in a long cycle of li|graphite half-cell.
Fig. 10 is a discharge capacity-coulombic efficiency result of a long cycle of the commercial modified ester-based electrolyte prepared in comparative example 3 in NCM 811|graphite full cells.
Fig. 11 is a discharge capacity-coulombic efficiency result of the electrolyte prepared in comparative example 4 in a long cycle in NCM 811|graphite full cell.
Fig. 12 is a ratio-cycle specific capacity-voltage curve of the electrolyte prepared in comparative example 5 in li|graphite half-cells.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. It will be apparent that the described embodiments are some, but not all, embodiments of the invention. All other embodiments, which can be made by a person skilled in the art without creative efforts, based on the described embodiments of the present invention fall within the protection scope of the present invention.
In order to more clearly state the aspects of the present application, the following examples are presented.
Example 1
A fast charge electrolyte for a high voltage lithium ion battery is prepared by the following steps:
anhydrous ethyl fluoroacetate (CAS: 459-72-3, molecular weight M=106) was prepared, 0.374g of lithium difluorosulfimide (CAS: 171611-11-3, molecular weight M=187) was added to 1mL of the above ethyl fluoroacetate, and then fluoroethylene carbonate (CAS: 114435-02-8, molecular weight M=106) and ethylene sulfate (CAS: 1072-53-3, molecular weight M=124) were added as additives, each in an amount of 5.0wt% of the non-lithium salt component of the electrolyte, and the electrolyte was stirred until clear, to form an electrolyte having a lithium salt concentration of 1.8 mol/L.
FIG. 1 is a graph of specific capacity voltage of the electrolyte prepared in example 1 in Li| graphite half-cell with a face capacity of 1mAh cm for a graphite pole piece -2 . As can be seen from fig. 1, the electrolyte described above has a capacity retention rate as high as 85.72% at a charge/discharge rate of 4C, based on the charge/discharge capacity at 0.1C rate. Compared with the traditional commercial ester electrolyte, the rate capability is greatly improved.
Example 2
A fast charge electrolyte for a high voltage lithium ion battery is prepared by the following steps:
anhydrous ethyl fluoroacetate (CAS: 459-72-3, molecular weight M=106) was prepared, 0.304g of lithium hexafluorophosphate (CAS: 21324-40-3, molecular weight M=152) was added to 1mL of the above anhydrous ethyl fluoroacetate, then additives fluoroethylene carbonate and ethylene sulfate were added in amounts of 5.0wt% of the non-lithium salt component of the electrolyte, and the electrolyte was stirred until clear, to form an electrolyte having a lithium salt concentration of 1.8 mol/L.
FIG. 2 is a graph of specific capacity voltage of the electrolyte prepared in example 2 in Li graphite half-cells, wherein the face capacity of the graphite pole piece is 1mAh cm -2 . As can be seen from fig. 2, the electrolyte described above has a capacity retention rate as high as 53.87% at a charge/discharge rate of 4C, based on the charge/discharge capacity at 0.1C rate. Compared with the traditional commercial ester-based electrolyte, the rate performance is still greatly improved.
Example 3
A fast charge electrolyte for a high voltage lithium ion battery is prepared by the following steps:
anhydrous ethyl difluoroacetate (CAS: 454-31-9, molecular weight M=124) was prepared, 0.374g of lithium difluorosulfonimide (CAS: 171611-11-3, molecular weight M=187) was added to 1mL of the above anhydrous ethyl difluoroacetate, then additives fluoroethylene carbonate and succinonitrile were added in an amount of 5.0wt% of the non-lithium salt component of the electrolyte, and the electrolyte was stirred until clear, forming an electrolyte having a lithium salt concentration of 1.8 mol/L.
FIG. 3 is a graph of specific capacity voltage of the electrolyte prepared in example 3 in Li graphite half-cells, wherein the face capacity of the graphite pole piece is 1mAh cm -2 . As can be seen from fig. 3, the electrolyte described above has a capacity retention rate as high as 87.28% at a charge/discharge rate of 4C, based on the charge/discharge capacity at 0.1C rate. Compared with the traditional commercial ester electrolyte, the rate capability is greatly improved.
Example 4
A fast charge electrolyte for a high voltage lithium ion battery is prepared by the following steps:
anhydrous grade methyl difluoroacetate (CAS: 433-53-4, molecular weight M=110) was prepared, 0.374g of lithium difluorosulfonimide (CAS: 171611-11-3, molecular weight M=187) was added to 1mL of the above anhydrous grade methyl difluoroacetate, then the additives fluorosulfonyl methyl difluoroacetate and adiponitrile were added, the additives were each 5.0% by weight of the non-lithium salt component of the electrolyte, and the electrolyte was stirred until clear, forming an electrolyte having a lithium salt concentration of 1.8 mol/L.
FIG. 4 is a graph of specific capacity voltage of the electrolyte prepared in example 4 in Li graphite half-cells, wherein the face capacity of the graphite pole piece is 1mAh cm -2 . As can be seen from fig. 4, the electrolyte described above has a capacity retention rate as high as 79.92% at a charge/discharge rate of 4C, based on the charge/discharge capacity at 0.1C rate. Compared with the traditional commercial ester electrolyte, the rate capability is greatly improved.
Example 5
A fast charge electrolyte for a high voltage lithium ion battery is prepared by the following steps:
anhydrous ethyl fluoroacetate (CAS: 459-72-3, molecular weight M=106) was prepared, 0.574g of lithium bistrifluoromethylsulfonylimide (CAS: 90076-65-6, molecular weight M=287) was added to 1mL of the above anhydrous ethyl fluoroacetate, and then additives lithium difluorophosphate and 1, 3-propane sultone (CAS: 1120-71-4, molecular weight M=122) were added, each in an amount of 5.0wt% of the non-lithium salt component of the electrolyte, and the electrolyte was stirred until clear, to form an electrolyte having a lithium salt concentration of 1.8 mol/L.
FIG. 5 is a graph of specific capacity efficiency of the electrolyte prepared in example 5 for long cycling at 1C rate in a Li I graphite half-cell, wherein the face capacity of the graphite pole piece is 1mAh cm -2 . As can be seen from fig. 5, the above electrolyte has a capacity retention rate of up to 92.93% after 200 cycles even when charge-discharge cycles are performed at a 1C rate. Compared with the traditional commercial ester-based electrolyte, the circulation stability performance under high multiplying power is greatly improved.
Example 6
A fast charge electrolyte for a high voltage lithium ion battery is prepared by the following steps:
anhydrous ethyl fluoroacetate (CAS: 459-72-3, molecular weight M=106) was prepared, 0.374g of lithium difluorosulfimide (CAS: 171611-11-3, molecular weight M=187) was added to 1mL of the above anhydrous ethyl fluoroacetate, and then additives fluoroethylene carbonate and ethylene sulfite (CAS: 3741-38-6, molecular weight M=108) were added, each in an amount of 2.5wt% of the non-lithium salt component of the electrolyte, and the electrolyte was stirred until clear, to form an electrolyte having a lithium salt concentration of 1.8 mol/L.
FIG. 6 is a graph showing the specific capacity efficiency of the electrolyte prepared in example 6 in a NCM811 graphite full cell at 0.5C rate for a long cycle, wherein the face capacity of the pole piece is 1mAh cm -2 . As can be seen from fig. 6, the electrolyte has a capacity retention rate as high as 90.22% after 200 cycles. Compared with the traditional commercial ester-based electrolyte, the circulation stability performance under high multiplying power is greatly improved.
Example 7
A fast charge electrolyte for a high voltage lithium ion battery is prepared by the following steps:
anhydrous ethyl fluoroacetate (CAS: 459-72-3, molecular weight M=106) and ethyl pentafluoropropionate (CAS: 426-65-3, molecular weight M=192) were prepared in a volume ratio of 1:1, 0.374g of lithium difluorosulfimide (CAS: 171611-11-3, molecular weight M=187) was added to 1mL of the above mixed solvent, and then additives fluoroethylene carbonate and ethylene sulfite (CAS: 3741-38-6, molecular weight M=108) were added, each in an amount of 2.5wt% of the non-lithium salt component of the electrolyte, and the electrolyte was stirred until clear, forming an electrolyte having a lithium salt concentration of 1.8 mol/L.
FIG. 7 is a graph showing the specific capacity efficiency of the electrolyte prepared in example 7 in a NCM811 graphite full cell at 0.5C rate for a long cycle, wherein the face capacity of the pole piece is 1mAh cm -2 . As can be seen from fig. 7, the electrolyte described above has a capacity retention rate of up to 90.15% after 200 cycles. Compared with the traditional commercial ester-based electrolyte, the circulation stability performance under high multiplying power is greatly improved.
Comparative example 1
0.152g of lithium hexafluorophosphate was dissolved in 0.9mL of a mixed solvent of ethylene carbonate (CAS: 96-49-1, molecular weight M=88) and dimethyl carbonate (CAS: 616-38-6, molecular weight M=90) (volume ratio: 3:7) to give a lithium salt lithium hexafluorophosphate concentration of 1.0mol/L. Stirring until the electrolyte is completely clarified, and obtaining the commercial ester-based electrolyte of the lithium battery.
FIG. 8 is a plot of specific capacity voltage of the electrolyte prepared in comparative example 1 in the rate capability of a Li| graphite half-cell, wherein the face capacity of the graphite pole piece is 1mAh cm -2 . As can be seen from fig. 8, the electrolyte solution has a capacity retention rate of only 13.65% when the charge/discharge rate is 4C, based on the charge/discharge capacity at 0.1C rate. Compared with the high-voltage quick-charge electrolyte, the rate capability of the electrolyte is greatly reduced.
Comparative example 2
0.184g of lithium hexafluorophosphate was dissolved in 0.9mL of a mixed solvent of ethylene carbonate, dimethyl carbonate and diethyl carbonate (CAS: 105-58-8, molecular weight M=118) (volume ratio: 1:1:1) to give a lithium hexafluorophosphate salt concentration of 1.2mol/L. Stirring until the electrolyte is completely clarified, and obtaining the commercial ester-based electrolyte of the lithium battery.
FIG. 9 is a graph of specific capacity efficiency of the electrolyte prepared in comparative example 2 for long cycling at 1C rate in a Li I graphite half-cell, wherein the face capacity of the graphite pole piece is 1mAh cm -2 . As can be seen from FIG. 9, the electrolyte was subjected to charge-discharge cycles at a rate of 1C, and the capacity retention rate after 200 cycles was only 62.71%, which is far lower than that of the present inventionHigh voltage fast charge electrolyte.
Comparative example 3
0.184g of lithium hexafluorophosphate is added into 0.9mL of mixed solvent of ethylene carbonate and dimethyl carbonate (volume ratio is 3:7), then fluoroethylene carbonate and ethylene sulfate which are additives are added, the content of each fluoroethylene carbonate and ethylene sulfate is 5.0 weight percent of the non-lithium salt component of the electrolyte, and the electrolyte is stirred until the electrolyte is clear, so that the commercial modified ester-based electrolyte of the lithium battery with the lithium salt concentration of 1.2mol/L is formed.
FIG. 10 is a graph showing the specific capacity efficiency of the electrolyte prepared in comparative example 3 in a NCM811 graphite full cell at a rate of 0.5C for a long cycle, wherein the face capacity of the pole piece is 1mAh cm -2 . As can be seen from fig. 10, the capacity retention rate of the electrolyte after 200 cycles is 68.95%, which is far lower than the high-voltage fast-charging electrolyte of the present invention.
Comparative example 4
Anhydrous ethyl fluoroacetate was prepared, 0.374g of lithium difluorosulfimide was added to 1mL of ethyl fluoroacetate, then fluoroethylene carbonate as an additive was added in an amount of 5.0wt% based on the non-lithium salt component of the electrolyte, and the electrolyte was stirred until clear to form an electrolyte having a lithium salt concentration of 1.8 mol/L.
FIG. 11 is a graph showing the specific capacity efficiency of the electrolyte prepared in comparative example 4 in a NCM811 graphite full cell at a rate of 0.5C for a long cycle, wherein the face capacity of the pole piece is 1mAh cm -2 . As can be seen from fig. 10, the electrolyte had a capacity retention of only 80.30% after 200 cycles. Far lower than the high-voltage fast-charging electrolyte of the invention.
Comparative example 5
Anhydrous ethyl fluoroacetate was prepared, 0.374g of lithium difluorosulfimide was added to 1mL of ethyl fluoroacetate, and then an additive vinyl sulfate was added in an amount of 5.0wt% based on the non-lithium salt component of the electrolyte, and the electrolyte was stirred until clear, forming an electrolyte having a lithium salt concentration of 1.8 mol/L.
FIG. 12 is a plot of specific capacity voltage for the rate capability of the electrolyte prepared in comparative example 5 in a Li|graphite half-cell, wherein the face capacity of the graphite pole piece is 1mAh cm -2 . From fig. 12, it can be seen thatThe electrolyte was found to have a capacity retention of 0 when the charge/discharge rate was 4C, based on the charge/discharge capacity at 0.1C rate.
Preparation and testing of li|graphite button half cell and NCM 811|graphite button full cell in examples 1 to 7 and comparative examples 1 to 5:
(1) Positive pole piece: liNi is added to 0.8 Co 0.1 Mn 0.1 O 2 Adding the binder PVDF and the conductive carbon black into N-methyl pyrrolidone (NMP) according to the ratio of 96:2:2, and uniformly mixing to obtain slurry; then coating the aluminum foil current collector, drying at 100 ℃, rolling, and cutting a wafer with the diameter of 12mm by a sheet punching machine;
(2) Li negative electrode: adopting a metal lithium sheet with the diameter of 15mm and the thickness of 20 mu m;
(3) Gr (graphite) anode: adding MCMB, a binder PAALi and conductive carbon black into water according to the ratio of 9:0.5:0.5, and uniformly mixing to obtain slurry; then coating the copper foil current collector, drying at 80 ℃, rolling, and cutting a wafer with the diameter of 14mm by a sheet punching machine;
(4) Electrolyte solution: the electrolytes prepared in examples 1 to 7 and comparative examples 1 to 5;
(5) A diaphragm: cutting a polyethylene single-layer diaphragm wafer with the diameter of 19mm by a sheet punching machine;
(6) And (3) battery assembly: in glove box (O) 2 <0.1ppm，H 2 O<0.1 ppm), assembling the button lithium battery in the order of positive electrode shell-positive electrode wafer-membrane wafer-negative electrode wafer-stainless steel sheet-spring piece-negative electrode shell, adding the electrolyte prepared in examples 1-7 and comparative examples 1-5, and finally packaging to obtain a test battery;
(7) And (3) battery testing:
the batteries corresponding to the electrolytes in examples 1 to 7 and comparative examples 1 to 5, the li|| graphite button half-cell and the NCM811|| graphite button full-cell were all operated at room temperature (25 ℃), the multiplying power cycle was performed at a multiplying power of 0.1C, 0.2C, 0.5C, 1C, 2C, 4C, 6C, 8C, 10C for 5 cycles, the long cycle test was performed at a multiplying power of 0.1C for 3 cycles, and then the charging and discharging were performed at a multiplying power of 0.5C; all test results are shown in fig. 1-12, and the results analysis and conclusion have been described in the examples and comparative examples, respectively.
Although the embodiments of the present invention are described above, the embodiments are only used for facilitating understanding of the present invention, and are not intended to limit the present invention. Any person skilled in the art can make any modification and variation in form and detail without departing from the spirit and scope of the present disclosure, but the scope of the present disclosure is to be determined by the appended claims.
Claims (10)
1. A lithium ion battery fast charge electrolyte comprising: organic solvents, lithium salts and additives; wherein the organic solvent is fluoro carboxylic ester.
2. The electrolyte of claim 1 wherein the fluorocarboxylate has the formula
The R is 1 And R is 2 Is an alkyl chain having 1 to 3 carbon atoms, and at least one of the alkyl chains contains a fluorine atom;
preferably, the specific structural formula of the fluorocarboxylic acid ester is
At least one of them.
3. The quick charge electrolyte for a lithium ion battery according to claim 1, wherein the additive is at least two of fluoroethylene carbonate, 1, 3-propane sultone, ethylene carbonate, lithium difluorophosphate, methyl fluorosulfonyl difluoroacetate, ethylene sulfate, ethylene sulfite, adiponitrile, succinonitrile.
4. The quick charge solution for a lithium ion battery of claim 1, wherein the lithium salt is at least one of lithium hexafluorophosphate, lithium bis-fluorosulfonyl imide, lithium bis-trifluoromethylsulfonyl imide, lithium difluoro oxalato borate, and lithium di-oxalato borate.
5. The lithium ion battery quick charge electrolyte according to claim 1, wherein the lithium salt accounts for 10-30% of the mass fraction of the lithium ion battery quick charge electrolyte;
and/or the additive accounts for 5-10% of the mass of the lithium ion battery quick-charge electrolyte.
6. The quick charge electrolyte for a lithium ion battery according to claim 2, wherein when the degree of substitution of fluorine atoms in the alkyl chain exceeds half, the solvent is compounded with a fluorocarboxylate having a degree of substitution of not more than three fluorine atoms.
7. A method for preparing the lithium ion battery quick-charge electrolyte according to any one of claims 1 to 6, wherein the organic solvent, lithium salt and additive are mixed.
8. A lithium ion battery comprising the fast charge electrolyte of the lithium ion battery of any one of claims 1-6.
9. The lithium ion battery of claim 8, further comprising a positive electrode and a negative electrode, wherein the active material in the positive electrode is an NCM ternary material; preferably, the NCM ternary material is LiNi x Mn y Co z O 2 Wherein x+y+z=1, and 0<x,y,z<1；
And/or the active material in the negative electrode is graphite.
10. According to claim 8The lithium ion battery is characterized in that the surface capacity of the positive electrode active material and the negative electrode active material is 0.5-3.5mAh cm -2 。
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