CN114628774A - Lithium ion battery - Google Patents
Lithium ion battery Download PDFInfo
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- CN114628774A CN114628774A CN202011467499.9A CN202011467499A CN114628774A CN 114628774 A CN114628774 A CN 114628774A CN 202011467499 A CN202011467499 A CN 202011467499A CN 114628774 A CN114628774 A CN 114628774A
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- positive electrode
- lithium ion
- ion battery
- carbonate
- electrolyte
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- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 title claims abstract description 31
- 229910001416 lithium ion Inorganic materials 0.000 title claims abstract description 31
- 150000001875 compounds Chemical class 0.000 claims abstract description 56
- 239000003792 electrolyte Substances 0.000 claims abstract description 52
- VAYTZRYEBVHVLE-UHFFFAOYSA-N 1,3-dioxol-2-one Chemical compound O=C1OC=CO1 VAYTZRYEBVHVLE-UHFFFAOYSA-N 0.000 claims abstract description 34
- 239000007774 positive electrode material Substances 0.000 claims abstract description 33
- 239000011255 nonaqueous electrolyte Substances 0.000 claims abstract description 24
- 229910052493 LiFePO4 Inorganic materials 0.000 claims abstract description 17
- 125000000217 alkyl group Chemical group 0.000 claims abstract description 10
- 239000002904 solvent Substances 0.000 claims abstract description 9
- 229910052736 halogen Inorganic materials 0.000 claims abstract description 6
- 125000004432 carbon atom Chemical group C* 0.000 claims abstract description 4
- 150000003839 salts Chemical class 0.000 claims abstract description 4
- 125000005843 halogen group Chemical group 0.000 claims abstract 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 20
- 239000000654 additive Substances 0.000 claims description 16
- 230000000996 additive effect Effects 0.000 claims description 13
- KMTRUDSVKNLOMY-UHFFFAOYSA-N Ethylene carbonate Chemical compound O=C1OCCO1 KMTRUDSVKNLOMY-UHFFFAOYSA-N 0.000 claims description 10
- XEKOWRVHYACXOJ-UHFFFAOYSA-N Ethyl acetate Chemical compound CCOC(C)=O XEKOWRVHYACXOJ-UHFFFAOYSA-N 0.000 claims description 9
- 239000007773 negative electrode material Substances 0.000 claims description 9
- 239000008151 electrolyte solution Substances 0.000 claims description 8
- 229910003002 lithium salt Inorganic materials 0.000 claims description 8
- 159000000002 lithium salts Chemical class 0.000 claims description 8
- JBTWLSYIZRCDFO-UHFFFAOYSA-N ethyl methyl carbonate Chemical compound CCOC(=O)OC JBTWLSYIZRCDFO-UHFFFAOYSA-N 0.000 claims description 7
- 229910021382 natural graphite Inorganic materials 0.000 claims description 6
- -1 propene sultone Chemical class 0.000 claims description 6
- FSSPGSAQUIYDCN-UHFFFAOYSA-N 1,3-Propane sultone Chemical compound O=S1(=O)CCCO1 FSSPGSAQUIYDCN-UHFFFAOYSA-N 0.000 claims description 4
- SBLRHMKNNHXPHG-UHFFFAOYSA-N 4-fluoro-1,3-dioxolan-2-one Chemical compound FC1COC(=O)O1 SBLRHMKNNHXPHG-UHFFFAOYSA-N 0.000 claims description 4
- 229910010941 LiFSI Inorganic materials 0.000 claims description 4
- 229910001290 LiPF6 Inorganic materials 0.000 claims description 4
- 229910012265 LiPO2F2 Inorganic materials 0.000 claims description 4
- 229910021383 artificial graphite Inorganic materials 0.000 claims description 4
- 229910052799 carbon Inorganic materials 0.000 claims description 4
- IEJIGPNLZYLLBP-UHFFFAOYSA-N dimethyl carbonate Chemical compound COC(=O)OC IEJIGPNLZYLLBP-UHFFFAOYSA-N 0.000 claims description 4
- VEWLDLAARDMXSB-UHFFFAOYSA-N ethenyl sulfate;hydron Chemical compound OS(=O)(=O)OC=C VEWLDLAARDMXSB-UHFFFAOYSA-N 0.000 claims description 4
- VDVLPSWVDYJFRW-UHFFFAOYSA-N lithium;bis(fluorosulfonyl)azanide Chemical compound [Li+].FS(=O)(=O)[N-]S(F)(=O)=O VDVLPSWVDYJFRW-UHFFFAOYSA-N 0.000 claims description 4
- ZZXUZKXVROWEIF-UHFFFAOYSA-N 1,2-butylene carbonate Chemical compound CCC1COC(=O)O1 ZZXUZKXVROWEIF-UHFFFAOYSA-N 0.000 claims description 3
- BJWMSGRKJIOCNR-UHFFFAOYSA-N 4-ethenyl-1,3-dioxolan-2-one Chemical compound C=CC1COC(=O)O1 BJWMSGRKJIOCNR-UHFFFAOYSA-N 0.000 claims description 3
- NEILRVQRJBVMSK-UHFFFAOYSA-N B(O)(O)O.C[SiH](C)C.C[SiH](C)C.C[SiH](C)C Chemical compound B(O)(O)O.C[SiH](C)C.C[SiH](C)C.C[SiH](C)C NEILRVQRJBVMSK-UHFFFAOYSA-N 0.000 claims description 3
- OIFBSDVPJOWBCH-UHFFFAOYSA-N Diethyl carbonate Chemical compound CCOC(=O)OCC OIFBSDVPJOWBCH-UHFFFAOYSA-N 0.000 claims description 3
- 229910013188 LiBOB Inorganic materials 0.000 claims description 3
- 229910013385 LiN(SO2C2F5)2 Inorganic materials 0.000 claims description 3
- 229910013406 LiN(SO2CF3)2 Inorganic materials 0.000 claims description 3
- 229910013426 LiN(SO2F)2 Inorganic materials 0.000 claims description 3
- XBDQKXXYIPTUBI-UHFFFAOYSA-M Propionate Chemical compound CCC([O-])=O XBDQKXXYIPTUBI-UHFFFAOYSA-M 0.000 claims description 3
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims description 3
- HMDDXIMCDZRSNE-UHFFFAOYSA-N [C].[Si] Chemical compound [C].[Si] HMDDXIMCDZRSNE-UHFFFAOYSA-N 0.000 claims description 3
- KXKVLQRXCPHEJC-UHFFFAOYSA-N acetic acid trimethyl ester Natural products COC(C)=O KXKVLQRXCPHEJC-UHFFFAOYSA-N 0.000 claims description 3
- 229910021389 graphene Inorganic materials 0.000 claims description 3
- 229910001547 lithium hexafluoroantimonate(V) Inorganic materials 0.000 claims description 3
- 229910001540 lithium hexafluoroarsenate(V) Inorganic materials 0.000 claims description 3
- 229910001496 lithium tetrafluoroborate Inorganic materials 0.000 claims 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 claims description 3
- KKQAVHGECIBFRQ-UHFFFAOYSA-N methyl propyl carbonate Chemical compound CCCOC(=O)OC KKQAVHGECIBFRQ-UHFFFAOYSA-N 0.000 claims description 3
- 239000004005 microsphere Substances 0.000 claims description 3
- PYLWMHQQBFSUBP-UHFFFAOYSA-N monofluorobenzene Chemical compound FC1=CC=CC=C1 PYLWMHQQBFSUBP-UHFFFAOYSA-N 0.000 claims description 3
- MHYFEEDKONKGEB-UHFFFAOYSA-N oxathiane 2,2-dioxide Chemical compound O=S1(=O)CCCCO1 MHYFEEDKONKGEB-UHFFFAOYSA-N 0.000 claims description 3
- ZRZFJYHYRSRUQV-UHFFFAOYSA-N phosphoric acid trimethylsilane Chemical compound C[SiH](C)C.C[SiH](C)C.C[SiH](C)C.OP(O)(O)=O ZRZFJYHYRSRUQV-UHFFFAOYSA-N 0.000 claims description 3
- QQONPFPTGQHPMA-UHFFFAOYSA-N propylene Natural products CC=C QQONPFPTGQHPMA-UHFFFAOYSA-N 0.000 claims description 3
- RUOJZAUFBMNUDX-UHFFFAOYSA-N propylene carbonate Chemical compound CC1COC(=O)O1 RUOJZAUFBMNUDX-UHFFFAOYSA-N 0.000 claims description 3
- 229910052710 silicon Inorganic materials 0.000 claims description 3
- 239000010703 silicon Substances 0.000 claims description 3
- 125000000325 methylidene group Chemical group [H]C([H])=* 0.000 claims 1
- 238000005056 compaction Methods 0.000 abstract description 31
- 238000003860 storage Methods 0.000 abstract description 16
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- 238000005336 cracking Methods 0.000 abstract description 2
- 230000007547 defect Effects 0.000 abstract description 2
- 230000000052 comparative effect Effects 0.000 description 13
- GELKBWJHTRAYNV-UHFFFAOYSA-K lithium iron phosphate Chemical compound [Li+].[Fe+2].[O-]P([O-])([O-])=O GELKBWJHTRAYNV-UHFFFAOYSA-K 0.000 description 13
- 230000006872 improvement Effects 0.000 description 11
- 238000000034 method Methods 0.000 description 11
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- 239000007789 gas Substances 0.000 description 7
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 7
- 239000011149 active material Substances 0.000 description 6
- 238000007086 side reaction Methods 0.000 description 6
- 230000002195 synergetic effect Effects 0.000 description 6
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- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 description 4
- 230000001351 cycling effect Effects 0.000 description 4
- 125000000753 cycloalkyl group Chemical group 0.000 description 4
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- 239000006245 Carbon black Super-P Substances 0.000 description 3
- 229910052782 aluminium Inorganic materials 0.000 description 3
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical group [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 3
- 238000007599 discharging Methods 0.000 description 3
- 230000008595 infiltration Effects 0.000 description 3
- 238000001764 infiltration Methods 0.000 description 3
- 230000014759 maintenance of location Effects 0.000 description 3
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 3
- 238000002156 mixing Methods 0.000 description 3
- GWAOOGWHPITOEY-UHFFFAOYSA-N 1,5,2,4-dioxadithiane 2,2,4,4-tetraoxide Chemical compound O=S1(=O)CS(=O)(=O)OCO1 GWAOOGWHPITOEY-UHFFFAOYSA-N 0.000 description 2
- 229920002134 Carboxymethyl cellulose Polymers 0.000 description 2
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- JAXFJECJQZDFJS-XHEPKHHKSA-N gtpl8555 Chemical compound OC(=O)C[C@H](N)C(=O)N[C@@H](CCC(O)=O)C(=O)N[C@@H](C(C)C)C(=O)N[C@@H](C(C)C)C(=O)N1CCC[C@@H]1C(=O)N[C@H](B1O[C@@]2(C)[C@H]3C[C@H](C3(C)C)C[C@H]2O1)CCC1=CC=C(F)C=C1 JAXFJECJQZDFJS-XHEPKHHKSA-N 0.000 description 2
- 238000002347 injection Methods 0.000 description 2
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- 101150058243 Lipf gene Proteins 0.000 description 1
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 1
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- 229920002614 Polyether block amide Polymers 0.000 description 1
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- 239000004698 Polyethylene Substances 0.000 description 1
- 239000002174 Styrene-butadiene Substances 0.000 description 1
- YKKPYMXANSSQCA-UHFFFAOYSA-N [3-[4-(aminomethyl)-6-(trifluoromethyl)pyridin-2-yl]oxyphenyl]-(3-pyrazol-1-ylazetidin-1-yl)methanone Chemical compound N1(N=CC=C1)C1CN(C1)C(=O)C1=CC(=CC=C1)OC1=NC(=CC(=C1)CN)C(F)(F)F YKKPYMXANSSQCA-UHFFFAOYSA-N 0.000 description 1
- ADKPKEZZYOUGBZ-UHFFFAOYSA-N [C].[O].[Si] Chemical compound [C].[O].[Si] ADKPKEZZYOUGBZ-UHFFFAOYSA-N 0.000 description 1
- 150000001335 aliphatic alkanes Chemical class 0.000 description 1
- 239000006183 anode active material Substances 0.000 description 1
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- 229920002239 polyacrylonitrile Polymers 0.000 description 1
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—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
-
- 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
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
- H01M4/5825—Oxygenated metallic salts or polyanionic structures, e.g. borates, phosphates, silicates, olivines
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Manufacturing & Machinery (AREA)
- Inorganic Chemistry (AREA)
- Physics & Mathematics (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- General Physics & Mathematics (AREA)
- Crystallography & Structural Chemistry (AREA)
- Materials Engineering (AREA)
- Secondary Cells (AREA)
- Battery Electrode And Active Subsutance (AREA)
Abstract
Aiming at overcoming the defect of high compaction LiFePO existing in the prior lithium ion battery4The cracking, gas generation and Fe are easy to occur under the high-temperature circulation condition2+The invention provides a lithium ion battery, which comprises a positive electrode, a negative electrode and a non-aqueous electrolyte, wherein the positive electrode comprises a positive electrode material layer, the compaction density of the positive electrode material layer is 2.35-3.0g/cc, the positive electrode material layer comprises a positive electrode active material, and the positive electrode active material is LiFePO4The non-aqueous electrolyte comprises a solvent, an electrolyte salt, vinylene carbonate and a compound shown in a structural formula 1A compound;
wherein n is 0-3, R is selected from halogen or alkyl or halogenated alkyl with 1-3 carbon atoms. The lithium ion battery provided by the invention can effectively solve the problem of high compaction of LiFePO4Has the problems of excellent high-temperature storage performance and high-temperature cycle performance.
Description
Technical Field
The invention belongs to the technical field of secondary batteries, and particularly relates to a lithium ion battery.
Background
In recent years, new energy automobiles and 3C consumer products are popularized on a larger scale, and requirements on the performance aspects of high energy density, high-rate charge and discharge, long service life, high safety and the like of lithium ion batteries are higher and higher. Compared with a ternary battery system, the lithium iron phosphate battery has obvious advantages in the aspects of safety, manufacturing cost, cycle life and the like. The lithium iron phosphate anode material suffers from the specific capacity, and the battery can obtain high energy density mainly by improving the compaction density of the anode and other ways at present. The compaction density of the positive plate is improved, so that the porosity of the positive plate is reduced, the infiltration rate of the electrolyte is low, the distribution uniformity of the electrolyte in the battery core is influenced, even the defects of lithium metal precipitation, poor dynamic performance and the like caused by poor infiltration of the electrolyte are possibly caused, and meanwhile, byproducts are generated on the surface of the negative electrode, so that the cycle life and the safety of the battery are influenced. Meanwhile, in the process of lithium ion insertion and extraction of the high-compaction-density cathode material, the volume change of the electrode is increased, and the porosity of the electrode is low, so that the particle fracture and Fe generation of the cathode active material are easily caused in the long-term circulation process2+The dissolution of the positive electrode active material, the falling of the positive electrode active material, the reduction of the battery capacity and the coulombic efficiency and the increase of the internal resistance, and the cycle performance of the battery is influenced.
The existing developed electrolyte suitable for the high-compaction pole piece mainly has two directions, one is to add a low-viscosity solvent to promote the infiltration of the electrolyte and improve the performances of the battery such as circulation, multiplying power and the like; and the other is that the service life of the battery is prolonged by adding an additive which reduces the impedance and promotes the circulation. However, both methods may cause deterioration of high temperature performance of the electrolyte and also severe ballooning phenomenon. Therefore, under the condition of ensuring high energy density of the battery, lithium can not be separated, and the high-temperature cycle and high-temperature storage performance of the battery can be improved, so that the method is a difficult problem for high-pressure compaction of the lithium iron phosphate battery electrolyte.
Generally, the improvement of the cell energy density and the improvement of the cell safety are a pair of contradictions in the performance of the battery, and how to balance the relationship among the dynamic performance, the energy density, the cycle life and the safety of the battery is a problem to be solved.
Disclosure of Invention
Aiming at the existing high-compaction LiFePO of the lithium ion battery4The cracking, gas generation and Fe are easy to occur under the high-temperature circulation condition2+The dissolution of the lithium ion battery leads to the problem of insufficient high-temperature cycle performance and high-temperature storage performance.
The technical scheme adopted by the invention for solving the technical problems is as follows:
the invention provides a lithium ion battery which comprises a positive electrode, a negative electrode and a non-aqueous electrolyte, wherein the positive electrode comprises a positive electrode material layer, the compacted density of the positive electrode material layer is 2.35-3.0g/cc, the positive electrode material layer comprises a positive electrode active material, and the positive electrode active material is LiFePO4The non-aqueous electrolyte comprises a solvent, an electrolyte salt, vinylene carbonate and a compound shown in a structural formula 1;
wherein n is 0-3, R is selected from halogen or alkyl or halogenated alkyl with 1-3 carbon atoms.
Optionally, the compound shown in the structural formula 1 is selected from one or more of compounds 1-12:
optionally, the addition amount of the compound shown in the structural formula 1 is 0.01-5% based on the total mass of the nonaqueous electrolyte solution as 100%.
Optionally, the addition amount of the vinylene carbonate is 0.1-5% based on the total mass of the nonaqueous electrolyte solution as 100%.
Optionally, the lithium salt is selected from LiPF6、LiBF4、LiBOB、LiDFOB、LiDFOP、LiPO2F2、LiSbF6、LiAsF6、LiN(SO2CF3)2、LiN(SO2C2F5)2、LiC(SO2CF3)3、LiN(SO2F)2And one or more of LiFSI;
in the nonaqueous electrolytic solution, the addition amount of the lithium salt is 0.1-4 mol/L.
Optionally, the solvent is selected from one or more of ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, propyl methyl carbonate, ethyl acetate and methyl acetate.
Optionally, the nonaqueous electrolyte solution further comprises an auxiliary additive, wherein the auxiliary additive is selected from one or more of 1, 3-propane sultone, 1, 4-butane sultone, fluoroethylene carbonate, vinyl sulfate, methylene methane disulfonate, tris (trimethylsilane) phosphate, tris (trimethylsilane) borate, propene sultone, fluorobenzene and vinyl ethylene carbonate.
Optionally, the additive amount of the auxiliary additive is 0.1-3% based on 100% of the total mass of the nonaqueous electrolyte.
Optionally, the negative electrode includes a negative electrode material layer including a negative electrode active material, and the negative electrode active material includes one or more of artificial graphite, natural graphite, silicon carbon, silicon oxygen carbon, intermediate carbon microspheres, and graphene.
According to the lithium ion battery provided by the invention, the inventor adds vinylene carbonate and the compound shown in the structural formula 1 into the electrolyte, and finds that the vinylene carbonate and the compound are used for inhibiting high-compaction LiFePO4Particle fragmentation, gas generation and Fe during high temperature charge-discharge cycling2+The dissolution of the compound has a better synergistic effect,presumably, the addition of the compound represented by the formula 1 can reduce the electrolyte concentration in LiFePO4The surface tension and contact angle of the active material surface are improved, thereby improving the LiFePO in a high-compaction state4The compatibility of the active substance and the electrolyte promotes the high-compaction LiFePO of the vinylene carbonate in the electrolyte4Thereby promoting LiFePO4The stable SEI film is formed on the surface of the active material, and meanwhile, the vinylene carbonate and the compound shown in the structural formula 1 are added together, so that the electrochemical stability window of the electrolyte can be effectively widened, the electrolyte is more difficult to oxidize in the using process, and the high-compaction LiFePO is inhibited4And the prepared lithium ion battery has excellent high-temperature storage performance and high-temperature cycle performance due to the side reaction on the surface.
The inventor discovers that in the compound shown in the structural formula 1, the carbon chain length of the cycloalkyl and the carbon chain length of the R group on the cycloalkyl are high compaction LiFePO for the compound through combination screening of a large number of compounds and vinylene carbonate4The performance improvement of the battery plays a decisive role when the carbon chain length of the cycloalkyl group or the carbon chain length of the R group is out of the range defined in the present invention, which is for high compaction of LiFePO4The lifting effect of the battery is not obvious, and even the battery plays a role in inhibiting.
It is noted that the electrolyte and the high compaction LiFePO provided by the invention4The active substance has a better complexing effect due to the low compaction of LiFePO4The active substance has no problems of particle breakage and difficult electrolyte penetration, and the addition of the electrolyte provided by the invention can cause the impedance increase, the gas production rate increase and Fe generation of the battery2+The dissolution problem of (b) is not favorable for improving the battery performance.
Drawings
Fig. 1 is a scanning electron microscope image of a positive electrode active material provided in example 1 of the present invention after high temperature cycling;
fig. 2 is a scanning electron micrograph of a positive electrode active material provided in comparative example 39 of the present invention after high temperature cycling.
Detailed Description
In order to make the technical problems, technical solutions and advantageous effects solved by the present invention more clearly apparent, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
The embodiment of the invention provides a lithium ion battery, which comprises a positive electrode, a negative electrode and a non-aqueous electrolyte, wherein the positive electrode comprises a positive electrode material layer, the compacted density of the positive electrode material layer is 2.35-3.0g/cc, the positive electrode material layer comprises a positive electrode active material, and the positive electrode active material is LiFePO4The non-aqueous electrolyte comprises a solvent, an electrolyte salt, vinylene carbonate and a compound shown in a structural formula 1;
wherein n is 0-6, R is H, halogen or alkyl or halogenated alkyl with 1-10 carbon atoms.
The inventor adds vinylene carbonate and a compound shown in a structural formula 1 into an electrolyte and finds that the vinylene carbonate and the compound are used for inhibiting high-compaction LiFePO4Particle fragmentation, gas generation and Fe during high temperature charge-discharge cycling2+The dissolution of (A) has a good synergistic effect, presumably because the addition of vinylene carbonate and the compound represented by the formula 1 together can reduce the electrolyte content in LiFePO4The surface tension and contact angle of the active material surface are improved, thereby improving the LiFePO in a high-compaction state4The compatibility of the active substance and the electrolyte promotes the high-compaction LiFePO of the vinylene carbonate in the electrolyte4Thereby promoting LiFePO4The stable SEI film is formed on the surface of the active material, and meanwhile, the vinylene carbonate and the compound shown in the structural formula 1 are added together, so that the electrochemical stability window of the electrolyte can be effectively widened, the electrolyte is more difficult to oxidize in the using process, and the high-compaction LiFePO is inhibited4And the prepared lithium ion battery has excellent high-temperature storage performance and high-temperature cycle performance due to the side reaction on the surface.
The inventor discovers that in the compound shown in the structural formula 1, the carbon chain length of the naphthenic base and the carbon chain length of the R group on the naphthenic base are high-compaction LiFePO for the compound through combination screening of a large number of compounds4The performance improvement of the battery plays a decisive role when the carbon chain length of the cycloalkyl group or the carbon chain length of the R group is out of the range defined in the present invention, which is for high compaction of LiFePO4The lifting effect of the battery is not obvious, and even the battery plays a role in inhibiting.
It is noted that the electrolyte and the high compaction LiFePO provided by the invention4The active substance has a better complexing effect due to the low compaction of LiFePO4The active substance has no problems of particle breakage and difficult electrolyte penetration, and the addition of the electrolyte provided by the invention can cause the internal resistance of the battery to be improved, the gas production to be improved and Fe to be generated2+The dissolution problem of (b) is not favorable for improving the battery performance.
In some embodiments, the compound of formula 1 is selected from one or more of compounds 1-12:
it should be noted that the selection of specific substances of the compound represented by the above formula 1 is only a preferable compound in the present application, and should not be construed as limiting the present invention.
In some embodiments, the compound represented by the formula 1 is added in an amount of 0.01 to 5% based on 100% by mass of the total nonaqueous electrolyte.
In a preferred embodiment, the compound represented by the formula 1 is added in an amount of 1 to 4% based on 100% by mass of the total nonaqueous electrolyte.
In the battery system and the electrolyte system provided by the invention, when the addition amount of the compound shown in the formula 1 in the nonaqueous electrolyte is in the range, the oxidation resistance of the nonaqueous electrolyte can be effectively improved, and simultaneously the LiFePO is obviously reduced4Internal resistance of active substance, is advantageousThe overall performance of the battery is improved, when the addition amount of the compound shown in the structural formula 1 is too low, the synergistic effect with the vinylene carbonate is difficult to embody, and the performance of the battery is not obviously improved; when the addition amount of the compound represented by formula 1 is excessively high, side reactions inside the battery increase, the battery impedance increases, and the battery cycle performance deteriorates on the contrary.
In various embodiments, the compound represented by the structural formula 1 may be added in an amount selected from the following values, based on 100% by mass of the nonaqueous electrolytic solution: 0.01%, 0.05%, 0.1%, 0.3%, 0.6%, 0.8%, 1%, 1.3%, 1.5%, 1.8%, 2.1%, 2.5%, 2.9%, 3%, 3.4%, 3.7%, 3.9%, 4.1%, 4.4%, 4.7%, 5%.
In some embodiments, the vinylene carbonate is added in an amount of 0.1 to 5% based on 100% by mass of the nonaqueous electrolytic solution.
In a preferred embodiment, the vinylene carbonate is added in an amount of 0.5 to 3% based on 100% by mass of the total nonaqueous electrolyte.
When the addition amount of the vinylene carbonate is too low, the synergistic effect with the compound shown in the structural formula 1 is difficult to be embodied, and the performance of the battery is not obviously improved; when the addition amount of the vinylene carbonate is too high, the gas production rate in the battery circulation process is improved, and the capacity fading is obvious.
In various embodiments, the vinylene carbonate may be added in an amount selected from the following values, based on 100% by mass of the nonaqueous electrolyte solution: 0.5%, 0.6%, 0.8%, 1%, 1.3%, 1.5%, 1.8%, 2.1%, 2.5%, 2.7%, 2.9%, 3%.
In some embodiments, the lithium salt is selected from LiPF6、LiBF4、LiBOB、LiDFOB、LiDFOP、LiPO2F2、LiSbF6、LiAsF6、LiN(SO2CF3)2、LiN(SO2C2F5)2、LiC(SO2CF3)3、LiN(SO2F)2And one or more of LiFSI;
in the nonaqueous electrolytic solution, the addition amount of the lithium salt is 0.1-4 mol/L.
In a preferred embodiment, the lithium salt is selected from LiPF6、LiPO2F2And one or more of LiFSI;
in the nonaqueous electrolytic solution, the addition amount of the lithium salt is 0.1-2 mol/L.
In some embodiments, the solvent is selected from one or more of ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, propyl methyl carbonate, ethyl acetate, and methyl acetate.
In a preferred embodiment, the solvent is selected from a mixture of ethylene carbonate, dimethyl carbonate and ethyl methyl carbonate.
In some embodiments, the nonaqueous electrolyte solution further comprises an auxiliary additive selected from one or more of 1, 3-propane sultone, 1, 4-butane sultone, fluoroethylene carbonate, vinyl sulfate, methylene methyl disulfonate, tris (trimethylsilane) phosphate, tris (trimethylsilane) borate, propene sultone, fluorobenzene and vinyl ethylene carbonate;
the additive amount of the auxiliary additive is 0.1-3% based on 100% of the total mass of the nonaqueous electrolyte.
In a preferred embodiment, the auxiliary additive is selected from one or more of 1, 3-propane sultone, methylene methanedisulfonate, fluoroethylene carbonate and vinyl sulfate.
In some embodiments, the anode includes an anode material layer including an anode active material including one or more of artificial graphite, natural graphite, silicon carbon, silicon oxy carbon, intermediate carbon microspheres, and graphene.
In a preferred embodiment, the negative active material is selected from one or more of artificial graphite, natural graphite, and silicon oxycarbide.
In some embodiments, the negative electrode material layer further includes a negative electrode conductive agent and a negative electrode binder.
In some embodiments, the negative electrode further comprises a negative electrode current collector for drawing current, and the negative electrode material layer is attached to the negative electrode current collector.
The negative electrode current collector may be selected from various existing metal materials, and in a preferred embodiment, the negative electrode current collector is selected from copper foil.
In some embodiments, the positive electrode material layer further includes a positive electrode conductive agent and a positive electrode binder.
In some embodiments, the positive electrode further comprises a positive electrode current collector for drawing current, and the positive electrode material layer is attached to the positive electrode current collector.
The positive electrode current collector may be selected from various existing metal materials, and in a preferred embodiment, the positive electrode current collector is selected from aluminum foil.
In some embodiments, the lithium ion battery further includes a separator, and the separator is located between the positive electrode and the negative electrode, and the separator includes one or more of a polyolefin separator, a polyamide separator, a polysulfone separator, a polyphosphazene separator, a polyethersulfone separator, a polyetheretherketone separator, a polyetheramide separator, and a polyacrylonitrile separator.
The present invention will be further illustrated by the following examples.
Example 1
This embodiment is used to illustrate a lithium ion battery and a method for manufacturing the same disclosed in the present invention, and includes the following operation steps:
1) preparing an electrolyte: mixing Ethylene Carbonate (EC) and Ethyl Methyl Carbonate (EMC) according to the mass ratio of EC: EMC of 3:7, and then adding lithium hexafluorophosphate (LiPF)6) To a molar concentration of 1mol/L, and then unsaturated ethylene carbonate shown in the following Table 1, a compound shown in the formula 1, and other additives were added, based on 100% of the total mass of the electrolyte.
2) Preparation of the Positive electrode
Mixing a positive active material lithium iron phosphate, conductive carbon black Super-P and a binder polyvinylidene fluoride (PVDF) according to a mass ratio of 93:4:3, and then dispersing the materials in N-methyl-2-pyrrolidone (NMP) to obtain positive slurry. And uniformly coating the slurry on two sides of the aluminum foil, drying, rolling and vacuum drying, and welding an aluminum outgoing line by using an ultrasonic welding machine to obtain the anode, wherein the thickness of the anode is 120-150 mu m. The resulting compacted density of the positive electrode material layer on the surface of the positive electrode is shown in table 1.
3) Preparation of negative plate
Mixing the modified natural graphite of the negative active material, conductive carbon black Super-P, Styrene Butadiene Rubber (SBR) and carboxymethyl cellulose (CMC) according to the mass ratio of 94:1:2.5:2.5, and then dispersing the modified natural graphite, the conductive carbon black Super-P, the SBR and the CMC in deionized water to obtain negative slurry. Coating the slurry on two sides of a copper foil, drying, rolling, and welding a nickel lead wire by an ultrasonic welding machine to obtain the negative electrode.
4) Preparation of cell
And placing a polyethylene microporous membrane with the thickness of 20 mu m between the positive plate and the negative plate as a diaphragm, winding a sandwich structure consisting of the positive plate, the negative plate and the diaphragm, flattening the wound body, placing the flattened wound body into an aluminum-plastic film, respectively leading out lead wires of the positive plate and the negative plate, and carrying out hot-press sealing on the aluminum-plastic film to obtain the battery cell to be injected with the liquid.
5) Liquid injection and formation of battery core
In a glove box with the dew point controlled below-40 ℃, the prepared electrolyte is injected into the battery core through the electrolyte injection hole, and the amount of the electrolyte is ensured to be full of the gap in the battery core. Then the formation is carried out according to the following steps: charging at 0.05C for 180min, charging at 0.1C for 180min, standing for 24hr, shaping, sealing, charging at 0.2C to 3.65V, standing at room temperature for 24hr, and discharging at 0.2C to 2.0V.
Examples 2 to 26
Examples 2 to 26 are provided to illustrate the nonaqueous electrolytic solution, the lithium ion battery and the preparation method thereof disclosed in the present invention, and include most of the operation steps in example 1, except that:
the compacted density of the positive electrode material layer on the surface of the positive electrode is shown in examples 2 to 26 in Table 1.
The unsaturated ethylene carbonate shown in examples 2-26 in Table 1, the compound shown in the structural formula 1 and other additives are respectively added based on the total mass of the electrolyte as 100%.
Comparative examples 1 to 55
Comparative examples 1 to 55 are for explaining a nonaqueous electrolytic solution, a lithium ion battery and a preparation method thereof disclosed by the present invention, and include most of the operation steps in example 1, except that:
the compacted density of the positive electrode material layer on the surface of the positive electrode is shown in comparative examples 1 to 55 in Table 1.
The unsaturated ethylene carbonate, the compound shown in the structural formula 1, the compound 13-the compound 20 and other additives shown in comparative examples 1-55 in the table 1 are respectively added by taking the total mass of the electrolyte as 100%.
Performance testing
The lithium ion batteries prepared in the above examples 1 to 26 and comparative examples 1 to 55 were subjected to the following performance tests:
high temperature cycle performance test
Charging to 3.65V at a constant current of 1C at 45 ℃, then charging at a constant voltage until the current is reduced to 0.1C, then discharging to 2.0V at a constant current of 1C, repeating the steps for 2000 weeks, recording the discharge capacity of 1 week and the discharge capacity of 2000 weeks, and calculating the capacity retention rate according to the following formula:
capacity retention rate (discharge capacity at week 2000 ÷ discharge capacity at week 1) × 100%
3.65V full electric state 60 ℃ storage test:
charging the battery with the capacity divided to 3.65V at room temperature according to 0.5C, stopping current at 0.02C, standing for 5min, discharging the battery at 0.5C to 2.0V, recording initial capacity D1, charging the battery to 3.65V at constant current and constant voltage of 0.5C, stopping current at 0.02C, and testing the thickness T1, voltage and internal resistance of the battery; after the fully charged battery is placed in a constant temperature box at 60 ℃ for storage for 30 days, the thermal thickness of the battery is measured and recorded as T2, the cold thickness T3, the voltage and the internal resistance of the battery are tested after the battery is placed at normal temperature for 4 hours, then the cold thickness T3, the voltage and the internal resistance of the battery are measured, the cold thickness D2 is recorded after the battery is placed at 0.5C to 2.0V, the battery is charged to 3.65V with a constant current and a constant voltage of 0.5C after the battery is placed for 5 minutes, the current is cut off at 0.02C, the battery is placed at 0.5C to 2.0V after the battery is placed for 5 minutes, and the recovery capacity D3 is recorded.
The battery thermal expansion rate (%) (T2-T1)/T1 × 100%;
battery capacity retention (%) ═ D2/D1 × 100%;
battery capacity recovery (%). D3/D1 × 100%
Contact angle test:
the method comprises the steps of taking a lithium iron phosphate positive plate as a test substrate of electrolyte to be tested, taking prepared electrolyte as the electrolyte to be tested, observing and photographing a dropping process of electrolyte drops to be tested by using a contact angle measuring instrument, analyzing an obtained picture by using a half-angle method to obtain contact angles of different electrolytes on the lithium iron phosphate positive plate, wherein the smaller the contact angle is, the stronger the permeability of the electrolyte on the plate is.
The test results obtained are filled in Table 1.
TABLE 1
From the test results of examples 1 to 12 and comparative example 39, it can be seen that: the addition of the compound 1-12 in the electrolyte containing Vinylene Carbonate (VC) has obvious performance improvement on high-temperature circulation at 45 ℃ and high-temperature storage at 60 ℃ and the like, and effectively inhibits Fe2+The dissolution was observed, and the improvement effect and the contact angle were almost the same. Namely, the added compounds 1-12 can obviously improve the high-temperature cycle and storage performance of the high-compaction-density lithium iron phosphate battery.
As can be seen by comparing example 1 with examples 13 to 18, as the content of the compound represented by formula 1 increases (0.1% to 5%), the performance becomes better and worse after 2000 cycles at 45 ℃ and 1C/1C and 30 days at 60 ℃. When the addition amount of the compound 1 in the electrolyte is 0.5%, the overall performance of the battery can be effectively improved, and the contact angle can be reduced; when the content is more than or less than 0.5%, the residual amount thereof in the positive electrode sheet also increases, and the excessive or insufficient amount of the compound represented by formula 1 increases side reactions inside the battery, increases battery resistance, deteriorates battery cycle, and the like.
From the test results of examples 1 to 12 and comparative examples 37 to 38, it can be seen that: the electrolyte does not contain Vinylene Carbonate (VC), so that the performance deterioration of high-temperature circulation at 45 ℃ and high-temperature storage at 60 ℃ is very obvious, and the gas generation and Fe are increased2+The VC and the compound shown in the structural formula 1 have good synergistic effect, can further reduce side reaction, and improve the cycle performance and high-temperature storage performance of the high-compaction-density lithium iron phosphate battery.
From examples 1 to 12, examples 19 to 21, and comparative examples 1 to 36, it can be seen that the addition of the compounds 1 to 12 to the electrolyte containing Vinylene Carbonate (VC) has a significant effect on the improvement of the high-temperature storage and cycle performance of the lithium iron phosphate batteries of 2.35, 2.5, 2.8, and 3.0g/cc, while the improvement of the high-temperature storage and cycle performance of the lithium iron phosphate batteries of 2.2, 1.9, and 1.7g/cc, which are low compacted densities, is poor. Secondly, the contact angle of the same electrolyte is the same, and the compaction density is an important parameter influencing the performance of the battery. Namely, the added compounds 1-12 have more remarkable effects on the high-temperature cycle and storage performance of high-compaction-density lithium iron phosphate batteries (2.35-3.0 g/cc).
It can be seen from examples 1 to 12 and comparative examples 40 to 55 that the addition of the compounds 1 to 12 to the electrolyte containing Vinylene Carbonate (VC) has the most significant improvement in the high-temperature storage and cycle performance of the high-pressure compacted lithium iron phosphate battery, while the addition of the compounds 13 to 20 has no good improvement effect. Wherein, the compounds 13-16 have no electron donating group (alkyl or halogen) compared with the compounds 1-12, so that the electrolyte has no electron donating group (alkyl or halogen) to LiFePO4The surface tension and compatibility of the active material surface are poor, thereby exhibiting poor electrochemical performance. Compared with the compounds 1-12, the compounds 17-19 have longer chain length of electron-donating alkane connected with the cyclic structure, increase the viscosity of the electrolyte and improve the internal resistance of the battery, thereby deteriorating the performances of high-temperature circulation, storage and the like of the battery. Compared with the compounds 1-12, the compound 20 has more carbon chains with a ring structure, so that the compound has poor synergistic effect with VC and has more side reactions in a battery, thereby deteriorating the high-temperature performance of the battery, namely the battery performance can be better improved by adding the compounds 1-12 in the high-compaction-density lithium iron phosphate battery.
Observation by electron microscope
After the lithium ion batteries obtained in example 1 and comparative example 39 were subjected to 45 ℃ 1C/1C cycle for 2000 weeks, the positive electrode active materials in the batteries were taken out, and observed by a scanning electron microscope, and images obtained are shown in fig. 1 and fig. 2, wherein fig. 1 is the positive electrode active material of example 1, and fig. 2 is the positive electrode active material of comparative example 39.
As can be seen from fig. 1 and 2, in comparative example 39, LiFePO after 2000 weeks of cycling with 2% VC added to the electrolyte only4There was significant particle breakage on the active material (fig. 2), whereas in example 1, LiFePO after 2000 weeks of cycling was obtained when 0.5% of compound 1 was added on the basis of 2% VC4The active substance has no particle breakage (fig. 1), so that the addition of the compound of formula 1 in combination with VC suppresses the high compaction of LiFePO4Rupture of the active particles.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.
Claims (10)
1. The lithium ion battery is characterized by comprising a positive electrode, a negative electrode and a non-aqueous electrolyte, wherein the positive electrode comprises a positive electrode material layer, the compacted density of the positive electrode material layer is 2.35-3.0g/cc, the positive electrode material layer comprises a positive electrode active material, and the positive electrode active material is LiFePO4The non-aqueous electrolyte comprises a solvent, an electrolyte salt, vinylene carbonate and a compound shown in a structural formula 1;
wherein n is 0-3, R is selected from halogen or alkyl or halogenated alkyl with 1-3 carbon atoms.
2. The lithium ion battery according to claim 1, wherein the compound represented by the structural formula 1 is one or more selected from compounds 1 to 12:
3. the lithium ion battery according to claim 1, wherein the compound represented by the structural formula 1 is added in an amount of 0.01 to 5% based on 100% by mass of the total nonaqueous electrolyte.
4. The lithium ion battery according to claim 1, wherein the vinylene carbonate is added in an amount of 0.1 to 5% based on 100% by mass of the total mass of the nonaqueous electrolyte solution.
5. The lithium ion battery of claim 1, wherein the lithium salt is selected from LiPF6、LiBF4、LiBOB、LiDFOB、LiDFOP、LiPO2F2、LiSbF6、LiAsF6、LiN(SO2CF3)2、LiN(SO2C2F5)2、LiC(SO2CF3)3、LiN(SO2F)2And LiFSI.
6. The lithium ion battery according to claim 5, wherein the amount of the lithium salt added to the nonaqueous electrolytic solution is 0.1 to 4 mol/L.
7. The lithium ion battery of claim 1, wherein the solvent is selected from one or more of ethylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, propyl methyl carbonate, ethyl acetate, and methyl acetate.
8. The lithium ion battery of claim 1, wherein the nonaqueous electrolyte further comprises an auxiliary additive, and the auxiliary additive is selected from one or more of 1, 3-propane sultone, 1, 4-butane sultone, fluoroethylene carbonate, vinyl sulfate, methylene methyldisulfonate, tris (trimethylsilane) phosphate, tris (trimethylsilane) borate, propene sultone, fluorobenzene, and vinyl ethylene carbonate.
9. The lithium ion battery according to claim 8, wherein the additive amount of the auxiliary additive is 0.1 to 3% based on 100% by mass of the total mass of the nonaqueous electrolyte solution.
10. The lithium ion battery of claim 1, wherein the negative electrode comprises a negative electrode material layer comprising a negative electrode active material comprising one or more of artificial graphite, natural graphite, silicon carbon, silicon oxycarbide, intermediate carbon microspheres, and graphene.
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