CN111640984A - Lithium ion finished product battery and preparation method thereof - Google Patents
Lithium ion finished product battery and preparation method thereof Download PDFInfo
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- CN111640984A CN111640984A CN202010421922.5A CN202010421922A CN111640984A CN 111640984 A CN111640984 A CN 111640984A CN 202010421922 A CN202010421922 A CN 202010421922A CN 111640984 A CN111640984 A CN 111640984A
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- lithium ion
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- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 title claims abstract description 97
- 229910001416 lithium ion Inorganic materials 0.000 title claims abstract description 97
- 238000002360 preparation method Methods 0.000 title abstract description 10
- 239000003792 electrolyte Substances 0.000 claims abstract description 109
- 239000000203 mixture Substances 0.000 claims abstract description 17
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 claims abstract description 6
- 229910052744 lithium Inorganic materials 0.000 claims abstract description 6
- 239000000654 additive Substances 0.000 claims description 92
- 230000000996 additive effect Effects 0.000 claims description 85
- BTGRAWJCKBQKAO-UHFFFAOYSA-N adiponitrile Chemical compound N#CCCCCC#N BTGRAWJCKBQKAO-UHFFFAOYSA-N 0.000 claims description 30
- IAHFWCOBPZCAEA-UHFFFAOYSA-N succinonitrile Chemical compound N#CCCC#N IAHFWCOBPZCAEA-UHFFFAOYSA-N 0.000 claims description 27
- 230000001681 protective effect Effects 0.000 claims description 22
- 229910003002 lithium salt Inorganic materials 0.000 claims description 19
- 159000000002 lithium salts Chemical class 0.000 claims description 19
- 239000002904 solvent Substances 0.000 claims description 19
- LNLFLMCWDHZINJ-UHFFFAOYSA-N hexane-1,3,6-tricarbonitrile Chemical compound N#CCCCC(C#N)CCC#N LNLFLMCWDHZINJ-UHFFFAOYSA-N 0.000 claims description 17
- 230000014759 maintenance of location Effects 0.000 claims description 12
- -1 nitrile compounds Chemical class 0.000 claims description 12
- 239000011356 non-aqueous organic solvent Substances 0.000 claims description 12
- QXWCSODZTTWWNT-UHFFFAOYSA-N propane;propane-1,2,3-triol Chemical compound CCC.OCC(O)CO QXWCSODZTTWWNT-UHFFFAOYSA-N 0.000 claims description 12
- VAYTZRYEBVHVLE-UHFFFAOYSA-N 1,3-dioxol-2-one Chemical compound O=C1OC=CO1 VAYTZRYEBVHVLE-UHFFFAOYSA-N 0.000 claims description 11
- SBLRHMKNNHXPHG-UHFFFAOYSA-N 4-fluoro-1,3-dioxolan-2-one Chemical compound FC1COC(=O)O1 SBLRHMKNNHXPHG-UHFFFAOYSA-N 0.000 claims description 10
- MTHSVFCYNBDYFN-UHFFFAOYSA-N diethylene glycol Chemical compound OCCOCCO MTHSVFCYNBDYFN-UHFFFAOYSA-N 0.000 claims description 10
- FKRCODPIKNYEAC-UHFFFAOYSA-N ethyl propionate Chemical compound CCOC(=O)CC FKRCODPIKNYEAC-UHFFFAOYSA-N 0.000 claims description 10
- AYKYXWQEBUNJCN-UHFFFAOYSA-N 3-methylfuran-2,5-dione Chemical compound CC1=CC(=O)OC1=O AYKYXWQEBUNJCN-UHFFFAOYSA-N 0.000 claims description 9
- PEDCQBHIVMGVHV-UHFFFAOYSA-N Glycerine Chemical compound OCC(O)CO PEDCQBHIVMGVHV-UHFFFAOYSA-N 0.000 claims description 9
- 150000005676 cyclic carbonates Chemical class 0.000 claims description 9
- FSSPGSAQUIYDCN-UHFFFAOYSA-N 1,3-Propane sultone Chemical compound O=S1(=O)CCCO1 FSSPGSAQUIYDCN-UHFFFAOYSA-N 0.000 claims description 8
- 150000007942 carboxylates Chemical class 0.000 claims description 6
- VEWLDLAARDMXSB-UHFFFAOYSA-N ethenyl sulfate;hydron Chemical compound OS(=O)(=O)OC=C VEWLDLAARDMXSB-UHFFFAOYSA-N 0.000 claims description 6
- IGILRSKEFZLPKG-UHFFFAOYSA-M lithium;difluorophosphinate Chemical compound [Li+].[O-]P(F)(F)=O IGILRSKEFZLPKG-UHFFFAOYSA-M 0.000 claims description 6
- 150000002825 nitriles Chemical class 0.000 claims description 6
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 claims description 5
- OIFBSDVPJOWBCH-UHFFFAOYSA-N Diethyl carbonate Chemical compound CCOC(=O)OCC OIFBSDVPJOWBCH-UHFFFAOYSA-N 0.000 claims description 5
- KMTRUDSVKNLOMY-UHFFFAOYSA-N Ethylene carbonate Chemical compound O=C1OCCO1 KMTRUDSVKNLOMY-UHFFFAOYSA-N 0.000 claims description 5
- RUOJZAUFBMNUDX-UHFFFAOYSA-N propylene carbonate Chemical compound CC1COC(=O)O1 RUOJZAUFBMNUDX-UHFFFAOYSA-N 0.000 claims description 5
- 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 4
- 230000008859 change Effects 0.000 claims description 4
- OOWFYDWAMOKVSF-UHFFFAOYSA-N 3-methoxypropanenitrile Chemical compound COCCC#N OOWFYDWAMOKVSF-UHFFFAOYSA-N 0.000 claims description 3
- IEJIGPNLZYLLBP-UHFFFAOYSA-N dimethyl carbonate Chemical compound COC(=O)OC IEJIGPNLZYLLBP-UHFFFAOYSA-N 0.000 claims description 3
- JBTWLSYIZRCDFO-UHFFFAOYSA-N ethyl methyl carbonate Chemical compound CCOC(=O)OC JBTWLSYIZRCDFO-UHFFFAOYSA-N 0.000 claims description 3
- 229910001496 lithium tetrafluoroborate Inorganic materials 0.000 claims description 3
- YKYONYBAUNKHLG-UHFFFAOYSA-N n-Propyl acetate Natural products CCCOC(C)=O YKYONYBAUNKHLG-UHFFFAOYSA-N 0.000 claims description 3
- 229940090181 propyl acetate Drugs 0.000 claims description 3
- 238000011084 recovery Methods 0.000 claims description 3
- NQPDZGIKBAWPEJ-UHFFFAOYSA-N valeric acid Chemical compound CCCCC(O)=O NQPDZGIKBAWPEJ-UHFFFAOYSA-N 0.000 claims description 3
- 239000011255 nonaqueous electrolyte Substances 0.000 claims description 2
- GJTXQVRENKDCNZ-UHFFFAOYSA-N acetylene;ethenyl hydrogen carbonate Chemical compound C#C.OC(=O)OC=C GJTXQVRENKDCNZ-UHFFFAOYSA-N 0.000 claims 1
- 238000000034 method Methods 0.000 abstract description 10
- 230000008569 process Effects 0.000 abstract description 9
- 230000005012 migration Effects 0.000 abstract description 2
- 238000013508 migration Methods 0.000 abstract description 2
- 230000000052 comparative effect Effects 0.000 description 15
- 239000006258 conductive agent Substances 0.000 description 10
- 238000012360 testing method Methods 0.000 description 10
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 8
- 239000011230 binding agent Substances 0.000 description 8
- 239000002002 slurry Substances 0.000 description 8
- 238000002156 mixing Methods 0.000 description 7
- 230000015572 biosynthetic process Effects 0.000 description 6
- SZXQTJUDPRGNJN-UHFFFAOYSA-N dipropylene glycol Chemical compound OCCCOCCCO SZXQTJUDPRGNJN-UHFFFAOYSA-N 0.000 description 6
- RTZKZFJDLAIYFH-UHFFFAOYSA-N ether Substances CCOCC RTZKZFJDLAIYFH-UHFFFAOYSA-N 0.000 description 6
- 238000004806 packaging method and process Methods 0.000 description 6
- 239000006230 acetylene black Substances 0.000 description 5
- 238000007599 discharging Methods 0.000 description 5
- 239000007773 negative electrode material Substances 0.000 description 5
- 239000007774 positive electrode material Substances 0.000 description 5
- 238000003860 storage Methods 0.000 description 5
- 238000004804 winding Methods 0.000 description 5
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 description 4
- 239000002033 PVDF binder Substances 0.000 description 4
- AVTOEKKTKXLWDL-UHFFFAOYSA-N acetylene;1,3-dioxolan-2-one Chemical compound C#C.O=C1OCCO1 AVTOEKKTKXLWDL-UHFFFAOYSA-N 0.000 description 4
- 239000001768 carboxy methyl cellulose Substances 0.000 description 4
- 239000011248 coating agent Substances 0.000 description 4
- 238000000576 coating method Methods 0.000 description 4
- 238000001035 drying Methods 0.000 description 4
- 239000012528 membrane Substances 0.000 description 4
- 229920002981 polyvinylidene fluoride Polymers 0.000 description 4
- 238000003825 pressing Methods 0.000 description 4
- 238000007493 shaping process Methods 0.000 description 4
- 239000007784 solid electrolyte Substances 0.000 description 4
- 238000003756 stirring Methods 0.000 description 4
- NDZWKTKXYOWZML-UHFFFAOYSA-N trilithium;difluoro oxalate;borate Chemical compound [Li+].[Li+].[Li+].[O-]B([O-])[O-].FOC(=O)C(=O)OF NDZWKTKXYOWZML-UHFFFAOYSA-N 0.000 description 4
- 238000009461 vacuum packaging Methods 0.000 description 4
- 239000004698 Polyethylene Substances 0.000 description 3
- 239000011888 foil Substances 0.000 description 3
- 238000002955 isolation Methods 0.000 description 3
- 229910003473 lithium bis(trifluoromethanesulfonyl)imide Inorganic materials 0.000 description 3
- VDVLPSWVDYJFRW-UHFFFAOYSA-N lithium;bis(fluorosulfonyl)azanide Chemical compound [Li+].FS(=O)(=O)[N-]S(F)(=O)=O VDVLPSWVDYJFRW-UHFFFAOYSA-N 0.000 description 3
- 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 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 3
- 229920002134 Carboxymethyl cellulose Polymers 0.000 description 2
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 2
- DPXJVFZANSGRMM-UHFFFAOYSA-N acetic acid;2,3,4,5,6-pentahydroxyhexanal;sodium Chemical compound [Na].CC(O)=O.OCC(O)C(O)C(O)C(O)C=O DPXJVFZANSGRMM-UHFFFAOYSA-N 0.000 description 2
- 239000013543 active substance Substances 0.000 description 2
- 229910021383 artificial graphite Inorganic materials 0.000 description 2
- 150000004649 carbonic acid derivatives Chemical class 0.000 description 2
- 235000010948 carboxy methyl cellulose Nutrition 0.000 description 2
- 239000008112 carboxymethyl-cellulose Substances 0.000 description 2
- 150000001768 cations Chemical class 0.000 description 2
- 239000008367 deionised water Substances 0.000 description 2
- 229910021641 deionized water Inorganic materials 0.000 description 2
- 238000002474 experimental method Methods 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 229910002804 graphite Inorganic materials 0.000 description 2
- 239000010439 graphite Substances 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- 238000009830 intercalation Methods 0.000 description 2
- 150000002500 ions Chemical class 0.000 description 2
- 229920006254 polymer film Polymers 0.000 description 2
- 235000019812 sodium carboxymethyl cellulose Nutrition 0.000 description 2
- 229920001027 sodium carboxymethylcellulose Polymers 0.000 description 2
- 229920003048 styrene butadiene rubber Polymers 0.000 description 2
- 239000002562 thickening agent Substances 0.000 description 2
- 229910032387 LiCoO2 Inorganic materials 0.000 description 1
- 229910052493 LiFePO4 Inorganic materials 0.000 description 1
- 229910003005 LiNiO2 Inorganic materials 0.000 description 1
- 229910013872 LiPF Inorganic materials 0.000 description 1
- 101150058243 Lipf gene Proteins 0.000 description 1
- 229910002097 Lithium manganese(III,IV) oxide Inorganic materials 0.000 description 1
- 229910014514 LixNiyM1-yO2 Inorganic materials 0.000 description 1
- 229910014512 LixNiyM1−yO2 Inorganic materials 0.000 description 1
- 239000004743 Polypropylene Substances 0.000 description 1
- XBDQKXXYIPTUBI-UHFFFAOYSA-M Propionate Chemical compound CCC([O-])=O XBDQKXXYIPTUBI-UHFFFAOYSA-M 0.000 description 1
- 229910006145 SO3Li Inorganic materials 0.000 description 1
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 1
- 230000001133 acceleration Effects 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 239000011149 active material Substances 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- 239000012300 argon atmosphere Substances 0.000 description 1
- 230000002238 attenuated effect Effects 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 229910052791 calcium Inorganic materials 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 239000002041 carbon nanotube Substances 0.000 description 1
- 229910021393 carbon nanotube Inorganic materials 0.000 description 1
- 150000001733 carboxylic acid esters Chemical class 0.000 description 1
- 238000006555 catalytic reaction Methods 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 229910052804 chromium Inorganic materials 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 230000008602 contraction Effects 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 230000001351 cycling effect Effects 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 238000009831 deintercalation Methods 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000008151 electrolyte solution Substances 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- VLKZOEOYAKHREP-UHFFFAOYSA-N hexane Substances CCCCCC VLKZOEOYAKHREP-UHFFFAOYSA-N 0.000 description 1
- 230000008595 infiltration Effects 0.000 description 1
- 238000001764 infiltration Methods 0.000 description 1
- 238000002347 injection Methods 0.000 description 1
- 239000007924 injection Substances 0.000 description 1
- 230000002687 intercalation Effects 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 229910052749 magnesium Inorganic materials 0.000 description 1
- 229910052748 manganese Inorganic materials 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 229910021645 metal ion Inorganic materials 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 229910052750 molybdenum Inorganic materials 0.000 description 1
- 238000005457 optimization Methods 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 238000011056 performance test Methods 0.000 description 1
- 229920000573 polyethylene Polymers 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
- 229920001155 polypropylene Polymers 0.000 description 1
- ANRWPZQLOGSFCU-UHFFFAOYSA-N propanoic acid prop-1-ene Chemical compound C=CC.C(CC)(=O)O ANRWPZQLOGSFCU-UHFFFAOYSA-N 0.000 description 1
- 239000011241 protective layer Substances 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 230000008439 repair process Effects 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 230000033764 rhythmic process Effects 0.000 description 1
- 238000007086 side reaction Methods 0.000 description 1
- 229910052814 silicon oxide Inorganic materials 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 230000008719 thickening Effects 0.000 description 1
- 229910052719 titanium Inorganic materials 0.000 description 1
- 229910052726 zirconium Inorganic materials 0.000 description 1
Images
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
- H01M10/052—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)
- Manufacturing & Machinery (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (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 provides a lithium ion finished product battery and a preparation method thereof. The lithium ion finished product battery is a lithium ion battery after being charged for the first time, the lithium ion battery comprises electrolyte, and when the electrolyte composition of the lithium ion finished product battery is within the range limited by the application, the cycle life of the lithium ion finished product battery is optimal, the consumption of the lithium ion battery on the components during the service life can be maintained, and therefore the lithium ion finished product battery has better cycle performance. Meanwhile, the electrolyte in the lithium ion battery has better dynamic performance, and can keep the resistance R of lithium ion migration in the using process of the lithium ion batteryGeneral assembly(RGeneral assembly＝Rsei+Rct+Rw) At minimum, the invention greatly reduces R through optimizing the experimental schemeGeneral assemblyA value of (1) to ensure lithium ionThe finished battery has better cycle performance.
Description
Technical Field
The invention belongs to the technical field of lithium ion batteries, and particularly relates to a lithium ion finished product battery and a preparation method thereof.
Background
In recent years, lithium ion batteries have been widely used in the fields of smart phones, tablet computers, smart wearing, electric tools, electric automobiles, and the like. With the acceleration of life rhythm and the development of electronic products, the demands of consumers on the charging environment and the energy density improvement of the lithium ion battery are more urgent, and correspondingly higher requirements on the use temperature range and the voltage of the lithium ion battery are provided; meanwhile, the lithium ion battery is required to have a long service life and high safety. At present, the research on the lithium ion battery electrolyte is stopped in the aspect of raw material addition, and few people pay attention to the component content of the electrolyte in the lithium ion finished battery.
Disclosure of Invention
The inventor finds that the content of electrolyte components in a lithium ion finished battery is related to the performances of cycle storage and the like, because the battery continuously consumes the electrolyte components during the cycle and storage processes. When the additive is contained in the electrolyte below a certain level, the life of the electrolyte is rapidly reduced. Based on the above, the invention provides a lithium ion finished battery and a preparation method thereof, and the purpose that the lithium ion finished battery has excellent cycle performance is achieved by controlling the electrolyte composition of the lithium ion finished battery within the range defined by the application.
Specifically, the technical scheme adopted by the invention is as follows:
a lithium ion finished product battery comprises a positive electrode, a negative electrode, a diaphragm and an electrolyte, wherein the electrolyte comprises a solvent, a conductive lithium salt, a positive electrode protection additive and a negative electrode film forming additive; wherein, the content of the anode protective additive accounts for 0.1-12 wt% of the total mass of the electrolyte, and the content of the cathode film forming additive accounts for 4-15 wt% of the total mass of the electrolyte.
According to the invention, the positive electrode protection additive is selected from nitrile compounds comprising at least three of succinonitrile, adiponitrile, dipropylene glycol ether, 1,3, 6-hexanetrinitrile, 3-methoxypropionitrile and glyceropropanetrinitrile.
According to the invention, the positive electrode protection additive is 0.1-3 wt% of adiponitrile, 0.1-2 wt% of dipropylene nitrile glycol ether and 0.1-5 wt% of 1,3, 6-hexanetrinitrile based on the total mass of the electrolyte.
According to the invention, the positive electrode protection additive is 0.1-3 wt% of adiponitrile, 0.1-2 wt% of succinonitrile and 0.1-5 wt% of 1,3, 6-hexanetrinitrile based on the total mass of the electrolyte.
According to the invention, the positive electrode protection additive is 0.1-3 wt% of adiponitrile, 0.1-2 wt% of succinonitrile and 0.1-4 wt% of glycerol propane trinitrile based on the total mass of the electrolyte.
According to the invention, the positive electrode protection additive is 0.1-3 wt% of adiponitrile, 0.1-5 wt% of 1,3, 6-hexanetrinitrile and 0.1-4 wt% of glycerol propanetrinitrile based on the total mass of the electrolyte.
According to the invention, the positive electrode protection additive is succinonitrile accounting for 0.1-2 wt% of the total mass of the electrolyte, 1,3, 6-hexanetricarbonitrile accounting for 0.1-5 wt% of the total mass of the electrolyte, and dipropylene nitrile glycol ether accounting for 0.1-2 wt% of the total mass of the electrolyte.
According to the invention, the positive electrode protection additive is 0.1-3 wt% of adiponitrile, 0.1-2 wt% of succinonitrile, 0.1-5 wt% of 1,3, 6-hexanetricarbonitrile and 0.1-2 wt% of dipropionitrile glycol ether in the total mass of the electrolyte.
According to the invention, the positive electrode protection additive is 0.1-3 wt% of adiponitrile, 0.1-2 wt% of succinonitrile, 0.1-4 wt% of 1,3, 6-hexanetricarbonitrile and 0.1-3 wt% of glycerol propane trinitrile in the total mass of the electrolyte.
According to the invention, the negative film-forming additive comprises fluoroethylene carbonate and 1, 3-propane sultone.
According to the invention, the content of the fluoroethylene carbonate accounts for 3-10 wt% of the total mass of the electrolyte, and the content of the 1, 3-propane sultone accounts for 1-5 wt% of the total mass of the electrolyte.
According to the present invention, the electrolyte further includes a low resistance additive selected from at least one of vinyl sulfate, lithium difluorophosphate, and lithium tetrafluoroborate.
According to the invention, the content of the low-impedance additive accounts for 0-2 wt% of the total mass of the nonaqueous electrolyte.
According to the invention, the electrolyte can also comprise at least one of vinylene carbonate, vinylene ethylene carbonate, 2-methyl maleic anhydride or lithium difluoro-oxalato-borate, and the content of the at least one of vinylene carbonate, vinylene ethylene carbonate, 2-methyl maleic anhydride or lithium difluoro-oxalato-borate is 0-2 wt% of the total mass of the electrolyte.
According to the present invention, the non-aqueous organic solvent is selected from a mixture of at least one of cyclic carbonates and at least one of linear carbonates and linear carboxylates, mixed in any proportion; the cyclic carbonate is selected from at least one of ethylene carbonate and propylene carbonate, the linear carbonate is selected from at least one of dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate, and the linear carboxylate is selected from at least one of ethyl propionate, propyl propionate and propyl acetate.
According to the invention, the mass fraction of the cyclic carbonate in the non-aqueous organic solvent is 10 to 50 wt%, based on 100 wt% of the total mass.
According to the invention, the charge cut-off voltage of the lithium ion finished battery is more than or equal to 4.4V.
According to the invention, the charging range of the lithium ion finished battery is 3.0V-4.45V.
According to the invention, the capacity retention rate of the lithium ion finished battery is more than or equal to 80% when the lithium ion finished battery is subjected to charge-discharge cycle for 500 weeks by using 1C current in a charge-discharge voltage interval under the condition of 45 ℃.
According to the invention, the capacity retention rate of the lithium ion finished battery after being stored for 6 hours at the high temperature of 85 ℃ is more than or equal to 80%.
According to the invention, the capacity recovery rate of the lithium ion finished battery after being stored for 6 hours at the high temperature of 85 ℃ is more than or equal to 90 percent.
According to the invention, the thickness change rate of the lithium ion finished battery after being stored for 6 hours at a high temperature of 85 ℃ is less than or equal to 10 percent.
According to the invention, the 0.4C rate discharge capacity retention rate of the lithium ion finished battery is more than or equal to 40 percent after the lithium ion finished battery is placed for 4 hours at the temperature of-20 ℃.
Has the advantages that:
the invention provides a lithium ion finished product battery and a preparation method thereof. The lithium ion finished product battery is a lithium ion battery after being charged for the first time, the lithium ion battery comprises electrolyte, and when the electrolyte composition of the lithium ion finished product battery is within the range limited by the application, the cycle life of the lithium ion finished product battery is optimal, the consumption of the lithium ion battery on the components during the service life can be maintained, and therefore the lithium ion finished product battery has better cycle performance. Meanwhile, the electrolyte in the lithium ion battery has better dynamic performance, and can keep the resistance R of lithium ion migration in the using process of the lithium ion batteryGeneral assembly(RGeneral assembly＝Rsei+Rct+Rw) At minimum, the invention greatly reduces R through optimizing the experimental schemeGeneral assemblyThe numerical value of (2) ensures that the lithium ion finished battery has better cycle performance.
Drawings
Fig. 1 shows the results of EIS tests of lithium ion finished batteries of example 1 and comparative examples 1 to 2 and comparative examples 8 to 10.
Detailed Description
< lithium ion Battery completed >
The lithium ion finished battery is prepared by winding the anode, the cathode and the diaphragm in sequence according to the preparation process of the lithium ion battery, placing the wound anode, cathode and diaphragm into an outer packaging shell, injecting electrolyte, packaging and finally forming.
Specifically, the preparation process of the lithium ion finished battery comprises the following steps:
and stacking the positive plate, the diaphragm and the negative plate in sequence to enable the diaphragm to be positioned between the positive plate and the negative plate to play a role in isolation, then winding to obtain a bare cell, placing the bare cell in an outer packaging shell, injecting the prepared electrolyte into the dried battery, and carrying out vacuum packaging, standing, formation, shaping and other processes to obtain the finished lithium ion battery.
Wherein the formation process comprises the following steps:
a. standing for 10min, setting the temperature to be 60-85 ℃, and using a battery with the pressure of 0.6-1.2 MPa;
b. charging to 3.7V at 0.2C under constant current, stopping for 15min, setting the temperature at 60-85 deg.C, and using 0.6-1.2 MPa voltage battery;
c. charging at 0.5C with constant current to cut-off voltage of the battery, wherein the cut-off time is 75min, the temperature is set to be 60-85 ℃, and the battery is pressed at 0.6-1.2 MPa; (wherein the cut-off voltage is not less than 4.4V).
As previously described, the present invention provides a lithium ion finished battery comprising a positive electrode, a negative electrode, a separator, and an electrolyte comprising a solvent, a conductive lithium salt, a positive electrode protective additive, and a negative electrode film-forming additive; wherein, the content of the anode protective additive accounts for 0.1-12 wt% of the total mass of the electrolyte, and the content of the cathode film forming additive accounts for 4-15 wt% of the total mass of the electrolyte.
Further, the positive electrode protection additive is selected from nitrile compounds including at least three of succinonitrile, adiponitrile, dipropylene glycol ether, 1,3, 6-hexanetrinitrile, 3-methoxypropionitrile, and glyceropropanetrinitrile.
Furthermore, the nitrile compound is added into the electrolyte as an anode protection additive, and can be complexed with the anode to form a structure similar to a protective layer, so that the anode is more stable, the side reaction decomposition of the electrolyte caused by the dissolution and catalysis of metal ions is avoided, the oxidation of electrolyte components on the surface of the anode is prevented, and the cycle performance of the lithium ion finished battery is improved. However, if the content of the positive electrode protective additive is more than 12 wt%, the excessive positive electrode protective additive is greatly complexedOn the surface of the positive electrode, lithium ions in the positive electrode are blocked from being extracted from the active material into the electrolyte, and thus have a resistance RseiThe larger the size, the larger the impedance of the solid electrolyte film on the surface of the positive electrode, the larger the resistance to the lithium ion intercalation at the positive electrode interface, and the faster the performance decay.
As described above, the content of the positive electrode protective additive accounts for 0.1-12 wt% of the total mass of the electrolyte. For example, 0.1 wt%, 0.3 wt%, 0.5 wt%, 0.8 wt%, 1 wt%, 1.5 wt%, 2 wt%, 2.5 wt%, 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, 10 wt%, 11 wt%, 12 wt%.
Further, the positive electrode protection additive is 0.1-3 wt% of adiponitrile, 0.1-2 wt% of dipropylene nitrile glycol ether and 0.1-5 wt% (preferably 0.1-4 wt%) of 1,3, 6-hexanetrinitrile based on the total mass of the electrolyte.
Further, the positive electrode protection additive is 0.1-3 wt% of adiponitrile, 0.1-2 wt% of succinonitrile and 0.1-5 wt% (preferably 0.1-4 wt%) of 1,3, 6-hexanetricarbonitrile based on the total mass of the electrolyte.
Further, the positive electrode protection additive is 0.1-3 wt% of adiponitrile, 0.1-2 wt% of succinonitrile and 0.1-4 wt% (preferably 0.1-3 wt%) of glycerol propane trinitrile based on the total mass of the electrolyte.
Further, the positive electrode protection additive is 0.1-3 wt% of adiponitrile, 0.1-5 wt% (preferably 0.1-4 wt%) of 1,3, 6-hexanetrinitrile and 0.1-4 wt% (preferably 0.1-3 wt%) of glycerol propane trinitrile based on the total mass of the electrolyte.
Further, the positive electrode protection additive is succinonitrile accounting for 0.1-2 wt% of the total mass of the electrolyte, 1,3, 6-hexanetricarbonitrile accounting for 0.1-5 wt% (preferably 0.1-4 wt%) of the total mass of the electrolyte, and dipropionitrile glycol ether accounting for 0.1-2 wt%.
Further, the positive electrode protection additive comprises 0.1-3 wt% of adiponitrile, 0.1-2 wt% of succinonitrile, 0.1-5 wt% (preferably 0.1-4 wt%) of 1,3, 6-hexanetricarbonitrile and 0.1-2 wt% of dipropylene glycol ether, wherein the adiponitrile, the succinonitrile, the 1,3, 6-hexanetricarbonitrile and the dipropylene glycol ether are all based on the total mass of the electrolyte.
Further, the positive electrode protection additive is adiponitrile, succinonitrile, 1,3, 6-hexanetricarbonitrile and glycerol propane trinitrile, wherein the adiponitrile, the succinonitrile, the 1,3, 6-hexanetricarbonitrile and the glycerol propane trinitrile account for 0.1-3 wt% of the total mass of the electrolyte.
In the above embodiment, the content of adiponitrile is also, for example, 0.1 wt%, 0.5 wt%, 0.8 wt%, 1 wt%, 1.2 wt%, 1.5 wt%, 1.6 wt%, 1.8 wt%, 2 wt%, 2.2 wt%, 2.5 wt%, 2.8 wt%, 3 wt%;
in the above embodiment, the content of 1,3, 6-hexanetricarbonitrile is also, for example, 0.1 wt%, 0.5 wt%, 0.8 wt%, 1 wt%, 1.2 wt%, 1.5 wt%, 1.6 wt%, 1.8 wt%, 2 wt%, 2.2 wt%, 2.5 wt%, 2.8 wt%, 3 wt%, 3.2 wt%, 3.5 wt%, 3.8 wt%, 4 wt%, 4.2 wt%, 4.5 wt%, 4.8 wt%, 5 wt%;
in the above embodiment, the content of the dipropylene glycol ether is, for example, 0.1 wt%, 0.5 wt%, 0.8 wt%, 1 wt%, 1.2 wt%, 1.5 wt%, 1.6 wt%, 1.8 wt%, 2 wt%;
in the above embodiment, the content of succinonitrile is also, for example, 0.1 wt%, 0.5 wt%, 0.8 wt%, 1 wt%, 1.2 wt%, 1.5 wt%, 1.6 wt%, 1.8 wt%, 2 wt%;
in the above embodiment, the content of glycerol propane trinitrile is also, for example, 0.1 wt%, 0.5 wt%, 0.8 wt%, 1 wt%, 1.2 wt%, 1.5 wt%, 1.6 wt%, 1.8 wt%, 2 wt%, 2.2 wt%, 2.5 wt%, 2.8 wt%, 3 wt%, 3.2 wt%, 3.5 wt%, 3.8 wt%, 4 wt%.
Further, the negative film forming additive comprises fluoroethylene carbonate and 1, 3-propane sultone.
As described above, the content of the negative electrode film forming additive accounts for 4-15 wt% of the total mass of the electrolyte. For example 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or 15 wt%.
Further, the fluoroethylene carbonate accounts for 3-10 wt% (such as 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, 10 wt%) of the total mass of the electrolyte, and the 1, 3-propane sultone accounts for 1-5 wt% (such as 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%) of the total mass of the electrolyte.
The negative electrode film forming additive combination provided by the invention can repair lithiumThe solid electrolyte membrane on the surface of the damaged negative electrode of the finished lithium ion battery is repeatedly used, so that the performance of the finished lithium ion battery is improved. However, if the content of the negative electrode film-forming additive is too high, a large amount of the negative electrode film-forming additive tends to form a very thick protective film on the surface of the negative electrode, such as LiF and Li in the protective film2SO4The content can be obviously improved, and the compactness of the protective film is greatly improved. Due to the impedance R of the lithium ion finished batteryseiAnd L ρ/Z (L is the thickness of the protective film, ρ is the density of the protective film, and Z is the specific surface area of the protective film), when the content of the negative electrode film-forming additive is too high, the values of L and ρ are remarkably increased, which easily causes the impedance of the solid electrolyte film on the surface of the negative electrode to be larger, and causes great resistance to the deintercalation of lithium ions at the negative electrode interface, thereby causing the performance to be rapidly attenuated.
Further, the electrolyte further includes a low impedance additive selected from at least one of vinyl sulfate, lithium difluorophosphate, and lithium tetrafluoroborate.
Further, the content of the low resistance additive is 0 to 2 wt%, preferably 0.01 to 0.2 wt% of the total mass of the nonaqueous electrolytic solution. For example, 0 wt%, 0.01 wt%, 0.02 wt%, 0.03 wt%, 0.04 wt%, 0.05 wt%, 0.06 wt%, 0.07 wt%, 0.08 wt%, 0.09 wt%, 0.1 wt%, 0.15 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%, 0.6 wt%, 0.7 wt%, 0.8 wt%, 0.9 wt%, 1 wt%, 1.2 wt%, 13 wt%, 1.5 wt%, 1.8 wt%, 2 wt%.
The low-impedance additive provided by the invention can reduce the impedance of a solid electrolyte membrane at an electrode interface, reduce the lithium ion de-intercalation resistance and further improve the cycle performance of a lithium ion battery. The principle of the low impedance additive for reducing impedance is to change the components of the positive and negative protective films and improve LiPO in the positive and negative protective filmsxFy、LiSO3CH2CH2SO3Li, etc., which is capable of conducting lithium ions by way of substitution, thereby lowering R in impedancect. When the low resistance additive is used in an excessive amount, it may form an excessive SEI film on the surface of the electrode, resulting in thickening of the SEI film and thus resistance deteriorationLarge, resulting in a substantial reduction in the high temperature cycling performance of the finished battery.
Further, the electrolyte can also comprise at least one of vinylene carbonate, vinylene ethylene carbonate, 2-methyl maleic anhydride or lithium difluoro oxalate borate, and the content of the vinylene carbonate, the vinylene ethylene carbonate, the 2-methyl maleic anhydride or the lithium difluoro oxalate borate accounts for 0-2 wt% of the total mass of the electrolyte.
The addition of the vinylene carbonate, the 2-methyl maleic anhydride or the lithium difluoro oxalate borate can further improve the cycle performance of the battery, and because an electrolyte membrane formed by the vinylene carbonate, the 2-methyl maleic anhydride or the lithium difluoro oxalate borate has higher strength, the electrolyte membrane is not easy to damage in the cycle process of the lithium ion battery, and further the consumption of other additives is reduced. The action principle is that the additive is easy to form a C-C polymer molecular structure on the surfaces of the anode and the cathode, and the additive is not easy to crack along with the expansion and contraction of the anode and the cathode when covering the surfaces of the anode and the cathode.
Further, the solvent is selected from non-aqueous organic solvents.
Further, the non-aqueous organic solvent is selected from a mixture in which at least one of cyclic carbonates and at least one of linear carbonates and linear carboxylates are mixed in an arbitrary ratio.
Preferably, the cyclic carbonate is selected from at least one of ethylene carbonate and propylene carbonate, the linear carbonate is selected from at least one of dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate, and the linear carboxylate is selected from at least one of ethyl propionate, propyl propionate and propyl acetate.
Further, the mass fraction of the cyclic carbonate in the non-aqueous organic solvent is 10 to 50 wt%, for example 20 to 40 wt%, such as 20 to 35 wt%, and the mass fraction of the linear carbonate and/or linear carboxylic ester is 50 to 90 wt%, for example 60 to 80 wt%, such as 65 to 80 wt%, based on 100 wt% of the total mass.
The non-aqueous organic solvent system provided by the invention has the characteristic of low viscosity, has a good infiltration effect on positive and negative pole pieces in a battery, has good dynamic performance, and can well prolong the cycle life of the battery.
Further, the conductive lithium salt is selected from at least one of lithium hexafluorophosphate, lithium bis (fluorosulfonyl) imide and lithium bis (trifluoromethanesulfonyl) imide.
Further, the concentration of the conductive lithium salt is 0.8 to 1.3mol/L, preferably 1 to 1.2mol/L, for example, 0.8mol/L, 0.9mol/L, 1mol/L, 1.1mol/L, 1.2mol/L, 1.3 mol/L.
The optimal concentration is provided, if the concentration of the lithium salt is too low, the conductivity of the electrolyte is low, so that the internal resistance of the battery is large, the circulation performance of lithium ions is easy to deteriorate, and if the concentration of the lithium salt is high, the viscosity of the electrolyte is high, so that the dynamic performance of the electrolyte is reduced, and the circulation performance deviation is caused.
In addition, within the solvent and lithium salt concentration ranges claimed herein. Lithium ions can be fully dissociated by the cyclic ester with large dielectric constant to form solvated cations, and the solvent has very small resistance, so that the diffusion speed of the solvated cations can be greatly increased, and the R is increasedwAnd further greatly improves the cycle performance of the lithium ion battery.
Further, the positive electrode includes a positive electrode active material, a binder, and a conductive agent, and the negative electrode includes a negative electrode active material, a binder, and a conductive agent.
Further, the mass ratio of the positive electrode active material, the binder, and the conductive agent is well known in the art.
Further, the mass ratio of the negative electrode active material, the binder, and the conductive agent is well known in the art.
Further, the positive electrode active material is selected from LiCoO2、LiNiO2、LiMn2O4、LiFePO4、LixNiyM1-yO2Wherein x is more than or equal to 0.9 and less than or equal to 1.2, and y is more than or equal to 0.5<1, M is selected from one or more of Co, Mn, Al, Mg, Ti, Zr, Fe, Cr, Mo, Cu and Ca.
Further, the negative active material is graphite or a graphite composite material containing 1-12 wt% SiOx/C or Si/C, wherein 2> x > 0.
Further, the conductive agent is selected from conductive agents known in the art for preparing a positive electrode or a negative electrode, for example, from acetylene black, carbon nanotubes, and the like.
Further, the separator is a separator known in the art, such as a polyethylene separator, a polypropylene separator, and the like.
Further, the charge cut-off voltage of the lithium ion finished battery is above 4.4V.
The invention also provides a preparation method of the lithium ion finished product battery, which comprises the following steps:
(1) preparing a positive plate and a negative plate, wherein the positive plate contains a positive active substance, and the negative plate contains a negative active substance;
(2) mixing a nonaqueous organic solvent, a conductive lithium salt and an additive to prepare an electrolyte;
(3) winding the positive plate, the diaphragm and the negative plate to obtain a naked battery cell without liquid injection; and (3) placing the bare cell in an outer packaging foil, injecting the electrolyte obtained in the step (2) into the dried bare cell, and performing vacuum packaging, standing, formation (first charging and discharging of the battery) and shaping to obtain the lithium ion finished battery.
Further, the method comprises the steps of:
fully stirring and mixing a positive active material lithium cobaltate, a conductive agent acetylene black and a binder polyvinylidene fluoride (PVDF) in an N-methyl pyrrolidone (NMP) solvent according to a mass ratio of 96:2:2 to form uniform positive slurry, coating the slurry on a positive current collector Al foil, drying and cold-pressing to obtain a positive plate;
fully stirring and mixing a negative active material artificial graphite, a conductive agent acetylene black, a binder Styrene Butadiene Rubber (SBR) and a thickening agent sodium carboxymethyl cellulose (CMC) in a deionized water solvent according to a mass ratio of 95:2:2:1 to form uniform negative slurry, coating the slurry on a negative current collector Cu foil, drying and cold pressing to obtain a negative plate;
taking a PE porous polymer film as a diaphragm;
and stacking the positive plate, the diaphragm and the negative plate in sequence to enable the diaphragm to be positioned between the positive plate and the negative plate to play a role in isolation, then winding to obtain a bare cell, placing the bare cell in an outer packaging shell, injecting the prepared electrolyte into the dried battery, and carrying out vacuum packaging, standing, formation, shaping and other processes to obtain the finished lithium ion battery.
Wherein the formation process comprises the following steps:
a. standing for 10min, setting the temperature at 65 ℃, and using a 0.8MPa piezoelectric cell;
b. charging to 3.7V at 0.2C under constant current, stopping for 15min, setting the temperature at 65 deg.C, and using 0.8MPa piezoelectric cell;
c. charging to 4.45V at 0.5C constant current, cut-off time of 75min, temperature of 65 deg.C, and using 0.8MPa voltage battery.
The present invention will be described in further detail with reference to specific examples. It is to be understood that the following examples are only illustrative and explanatory of the present invention and should not be construed as limiting the scope of the present invention. All the technologies realized based on the above-mentioned contents of the present invention are covered in the protection scope of the present invention.
The experimental methods used in the following examples are all conventional methods unless otherwise specified; reagents, materials and the like used in the following examples are commercially available unless otherwise specified.
The EIS test conditions used in the following examples were: the cell was adjusted to 50% SOC and tested at a frequency of 100kHz to 100MHz using an electrochemical workstation at 25 ℃.
The lithium ion batteries of the following comparative examples and examples were prepared according to the following preparation methods, except for the differences in the electrolytes, and the specific differences in the compositions of the electrolytes are shown in table 1.
(1) Preparing an electrolyte: at water content<In a 10ppm argon atmosphere glove box, uniformly mixing Ethylene Carbonate (EC), diethyl carbonate (DEC), Propylene Carbonate (PC), Ethyl Propionate (EP) and Propyl Propionate (PP) according to a certain mass ratio to obtain a nonaqueous organic solvent, and then mixing the nonaqueous organic solvent and the propylene propionate according to a certain mass ratioAdding negative film forming additives 1, 3-Propane Sultone (PS), fluoroethylene carbonate (FEC), positive electrode protection additives Succinonitrile (SN), Adiponitrile (ADN), dipropylene nitrile glycol ether (DENE), 1,3, 6-Hexane Trinitrile (HTCN), glycerol propane trinitrile, low-impedance additives vinyl sulfate (DTD) and lithium difluorophosphate (LiPO) into a non-aqueous organic solvent for calculating the total mass of the electrolyte2F2) And lithium salt lithium hexafluorophosphate (LiPF)6) Lithium bis (fluorosulfonyl) imide (LiFSI), lithium bis (trifluoromethanesulfonyl) imide (LiTFSI).
(2) Preparing a positive plate: fully stirring and mixing a positive active material lithium cobaltate, a conductive agent acetylene black and a binder polyvinylidene fluoride (PVDF) in a solvent of N-methyl pyrrolidone (NMP) according to a mass ratio of 96:2:2 to form uniform positive slurry, coating the slurry on a positive current collector Al foil, drying and cold-pressing to obtain a positive plate.
(3) Preparing a negative plate: fully stirring and mixing the artificial graphite serving as the negative active material, acetylene black serving as a conductive agent, Styrene Butadiene Rubber (SBR) serving as a binder and sodium carboxymethyl cellulose (CMC) serving as a thickening agent in a deionized water solvent according to the mass ratio of 95:2:2:1 to form uniform negative slurry, coating the slurry on a Cu foil serving as a negative current collector, drying and cold-pressing to obtain a negative plate.
(4) A diaphragm: a PE porous polymer film is used as a separator.
(5) Preparing a lithium ion battery: and sequentially stacking the positive plate, the diaphragm and the negative plate to enable the diaphragm to be positioned between the positive plate and the negative plate to play a role in isolation, then winding to obtain a bare cell, placing the bare cell in an outer packaging shell, injecting the prepared electrolyte into the dried battery, and carrying out vacuum packaging, standing, formation (first charging and discharging of the battery), shaping and other processes to obtain the lithium ion finished battery.
Examples 1 to 7
Before the first charge and discharge, the electrolyte consists of a solvent, a negative electrode film forming additive, a positive electrode protection additive, a low impedance additive and a lithium salt. After the lithium ion finished battery after the first charge and discharge is disassembled, a GC-2014C gas chromatograph (FID detector) is used for testing organic components in the electrolyte, an ion chromatograph (Switzerland 930 integrated ion chromatograph) is used for testing lithium salts in the electrolyte, and the tested electrolyte components are shown in Table 1.
Example 8
Before the first charge and discharge, the electrolyte consists of a solvent, a negative electrode film forming additive, a positive electrode protection additive, a low-impedance additive, Vinylene Carbonate (VC) and lithium salt serving as other additives. The specific electrolyte composition was also analyzed after the first charge and discharge of the lithium ion battery was disassembled, and the results are shown in table 1.
Example 9
Before the first charge and discharge, the electrolyte consists of a solvent, a negative electrode film forming additive, a positive electrode protection additive, a low-impedance additive, other additives 2-methyl maleic anhydride (SA) and lithium salt. The specific electrolyte composition was also analyzed after the first charge and discharge of the lithium ion battery was disassembled, and the results are shown in table 1.
Example 10
Before the first charge and discharge, the electrolyte consists of a solvent, a negative electrode film forming additive, a positive electrode protection additive, a low-impedance additive, Vinylene Carbonate (VC) and lithium salt serving as other additives. The specific electrolyte composition was also analyzed after the first charge and discharge of the lithium ion battery was disassembled, and the results are shown in table 1.
Comparative examples 1 to 4
Before the first charge and discharge, the electrolyte consists of a solvent, a negative electrode film forming additive, a positive electrode protection additive, a low impedance additive and a lithium salt. The specific electrolyte composition was also analyzed after the first charge and discharge of the lithium ion battery was disassembled, and the results are shown in table 1.
Comparative example 5
The electrolyte before first charging and discharging is composed of a solvent, a positive electrode protection additive, a low-impedance additive and a lithium salt. The specific electrolyte composition was also analyzed after the first charge and discharge of the lithium ion battery was disassembled, and the results are shown in table 1.
Comparative example 6
The electrolyte before first charging and discharging is composed of a solvent, a negative electrode film forming additive, a low impedance additive and a lithium salt. The specific electrolyte composition was also analyzed after the first charge and discharge of the lithium ion battery was disassembled, and the results are shown in table 1.
Comparative example 7
Before the first charge and discharge, the electrolyte consists of a solvent, a positive electrode protection additive, a negative electrode film forming additive and lithium salt. The specific electrolyte composition was also analyzed after the first charge and discharge of the lithium ion battery was disassembled, and the results are shown in table 1.
Comparative examples 8 to 10
Before the first charge and discharge, the electrolyte consists of a solvent, a negative electrode film forming additive, a positive electrode protection additive, a low impedance additive and a lithium salt. The specific electrolyte composition was also analyzed after the first charge and discharge of the lithium ion battery was disassembled, and the results are shown in table 1.
TABLE 1 composition of lithium ion batteries prepared in comparative examples and examples (unit: mass fraction wt%)
In the table, SN is succinonitrile, ADN is adiponitrile, DENE is dipropylene glycol ether, HTCN is 1,3, 6-hexanetricarbonitrile, PS is 1, 3-propanesultone, FEC is fluoroethylene carbonate, DTD is vinyl sulfate,/is that this component is not added, 0 means that this component is added but the content is less than the lower detection limit or that the consumption is complete.
The lithium ion batteries in the examples and the comparative examples were subjected to high-temperature cycle performance tests under the following specific test conditions:
high-temperature cycle test:
the batteries obtained in the examples and the comparative examples are placed at 45 ℃, the charge and discharge cycles are carried out by using 1C current under the charge and discharge voltage interval of 3.0-4.45V, the initial capacity is recorded as Q, and the capacity selected from the cycle to 500 weeks is recorded as Q1The capacity retention ratio (%) Q of the battery at 500 weeks of high-temperature cycle was calculated by the following formula1The results are reported in Table 2.
TABLE 2
As can be seen from the results of table 2: the high-temperature cycle performance of the lithium ion finished battery is obviously improved.
The lithium ion batteries in the examples and comparative examples were tested for high-temperature storage and low-temperature discharge performance under the following specific test conditions:
high temperature storage at 85 ℃ for 6 hours experiment: the batteries obtained in the examples and comparative examples were subjected to a charge-discharge cycle test at room temperature for 3 times at a charge-discharge rate of 1C, and then the 1C rate was charged to a full charge state, and the highest discharge capacity Q of the previous 3 1C cycles was recorded2And measuring the thickness D of the battery0. The fully charged cells were stored at 85 ℃ for 6 hours and the 1C discharge capacity Q of the cells after 6 hours was recorded3And the maximum discharge capacity Q was recorded 3 times by charging and discharging with 1C rate6While measuring the thickness D of the battery in the full state1And calculating to obtain the capacity retention rate of the battery after storage, and recording the gas production condition of the battery, wherein the recording result is shown in table 3. The calculation formula used therein is as follows: capacity retention (%) ═ Q3/Q2× 100%, capacity recovery ratio (%). Q6/Q2× 100%, and the thickness change rate (%) (D)1-D0)/D0×100％。
And (3) low-temperature discharge test: the cells obtained in examples and comparative examples were subjected to 3 charge-discharge cycles at room temperature at a rate of 1C, and then charged to a full charge state at a rate of 1C, and a 1C capacity Q was recorded4. The battery in full charge state is placed at-20 ℃ for 4h, then discharged to 3V at 0.4C rate, and the discharge capacity Q is recorded5The low-temperature discharge capacity retention rate was calculated, and the low-temperature discharge capacity retention rate of the battery, capacity retention rate (%) ═ Q, was calculated from the following formula5/Q4× 100, and the results are reported in Table 3.
TABLE 3
As can be seen from comparison between examples and comparative examples, the addition and optimization of the composition of the electrolyte, the EIS test results of lithium ion batteries assembled with electrolytes not within the scope of the present invention showed significantly greater impedance and significant deterioration of the final cycle performance.
The embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiment. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (11)
1. A lithium ion finished product battery comprises a positive electrode, a negative electrode, a diaphragm and an electrolyte, wherein the electrolyte comprises a solvent, a conductive lithium salt, a positive electrode protection additive and a negative electrode film forming additive; wherein, the content of the anode protective additive accounts for 0.1-12 wt% of the total mass of the electrolyte, and the content of the cathode film forming additive accounts for 4-15 wt% of the total mass of the electrolyte.
2. The finished battery as claimed in claim 1, wherein the positive electrode protection additive is selected from nitrile compounds including at least three of succinonitrile, adiponitrile, dipropionitrile glycol ether, 1,3, 6-hexanetrinitrile, 3-methoxypropionitrile, and glycerol propanetrinitrile.
3. The finished battery as claimed in claim 1 or 2, wherein the positive electrode protective additive is 0.1-3 wt% adiponitrile, 0.1-2 wt% dipropylene nitrile glycol ether, 0.1-5 wt% 1,3, 6-hexanetricarbonitrile; or,
the positive electrode protective additive is adiponitrile accounting for 0.1-3 wt% of the total mass of the electrolyte, succinonitrile accounting for 0.1-2 wt% of the total mass of the electrolyte, and 1,3, 6-hexanetricarbonitrile accounting for 0.1-5 wt% of the total mass of the electrolyte; or,
the positive electrode protective additive is adiponitrile, succinonitrile and glycerol propane trinitrile, wherein the adiponitrile, the succinonitrile and the glycerol propane trinitrile account for 0.1-3 wt% of the total mass of the electrolyte; or,
the positive electrode protective additive is adiponitrile accounting for 0.1-3 wt% of the total mass of the electrolyte, 1,3, 6-hexanetricarbonitrile accounting for 0.1-5 wt% of the total mass of the electrolyte, and glycerol propanetrinitrile accounting for 0.1-4 wt% of the total mass of the electrolyte; or,
the positive electrode protective additive is succinonitrile accounting for 0.1-2 wt% of the total mass of the electrolyte, 1,3, 6-hexanetricarbonitrile accounting for 0.1-5 wt% of the total mass of the electrolyte, and dipropylene nitrile glycol ether accounting for 0.1-2 wt% of the total mass of the electrolyte; or,
the positive electrode protective additive is 0.1-3 wt% of adiponitrile, 0.1-2 wt% of succinonitrile, 0.1-5 wt% of 1,3, 6-hexanetrinitrile and 0.1-2 wt% of dipropionitrile glycol ether; or,
the positive electrode protective additive comprises adiponitrile, succinonitrile, 1,3, 6-hexanetricarbonitrile and 0.1-3 wt% of glycerol propane trinitrile, wherein the adiponitrile, the succinonitrile, the 1,3, 6-hexanetricarbonitrile and the glycerol propane trinitrile account for 0.1-3 wt% of the total mass of the electrolyte.
4. The finished battery of any of claims 1-3, wherein the negative film-forming additive comprises fluoroethylene carbonate and 1, 3-propane sultone.
5. The finished battery as claimed in claim 4, wherein the fluoroethylene carbonate is present in an amount of 3-10 wt% and the 1, 3-propane sultone is present in an amount of 1-5 wt% based on the total mass of the electrolyte.
6. The finished battery of any of claims 1-5, wherein the electrolyte further comprises a low impedance additive selected from at least one of vinyl sulfate, lithium difluorophosphate, and lithium tetrafluoroborate.
7. The finished battery as claimed in claim 6, wherein the low impedance additive is present in an amount of 0-2 wt% of the total mass of the nonaqueous electrolyte.
8. The finished battery of any of claims 1-7 wherein the electrolyte further comprises at least one of vinylene carbonate, vinylene vinyl carbonate, 2-methyl maleic anhydride, or lithium difluoro-oxalato-borate in an amount of 0-2 wt% of the total mass of the electrolyte.
9. The finished battery of any of claims 1-8, wherein the non-aqueous organic solvent is selected from a mixture of at least one of a cyclic carbonate and at least one of a linear carbonate and a linear carboxylate in any proportion; the cyclic carbonate is selected from at least one of ethylene carbonate and propylene carbonate, the linear carbonate is selected from at least one of dimethyl carbonate, diethyl carbonate and ethyl methyl carbonate, and the linear carboxylate is selected from at least one of ethyl propionate, propyl propionate and propyl acetate.
10. The finished battery as claimed in claim 9, wherein the mass fraction of the cyclic carbonate in the non-aqueous organic solvent is 10-50 wt%, based on 100 wt% of the total mass.
11. The finished battery of any of claims 1-10 having at least one of the following (1) - (6):
(1) the capacity retention rate of the lithium ion finished battery is more than or equal to 80 percent when the lithium ion finished battery is subjected to charge-discharge circulation for 500 weeks by using 1C current in a charge-discharge voltage interval under the condition of 45 ℃;
(2) the capacity retention rate of the lithium ion finished battery after being stored for 6 hours at the high temperature of 85 ℃ is more than or equal to 80 percent;
(3) the capacity recovery rate of the lithium ion finished battery after being stored for 6 hours at the high temperature of 85 ℃ is more than or equal to 90 percent;
(4) the thickness change rate of the lithium ion finished battery after being stored for 6 hours at the high temperature of 85 ℃ is less than or equal to 10 percent;
(5) the retention rate of 0.4 discharge capacity of the lithium ion finished battery after being placed for 4 hours at the temperature of minus 20 ℃ is more than or equal to 40 percent;
(6) the charge cut-off voltage of the lithium ion finished battery is more than or equal to 4.4V.
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Application publication date: 20200908 |