CN116706253A - Lithium ion secondary battery - Google Patents
Lithium ion secondary battery Download PDFInfo
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- CN116706253A CN116706253A CN202310950719.0A CN202310950719A CN116706253A CN 116706253 A CN116706253 A CN 116706253A CN 202310950719 A CN202310950719 A CN 202310950719A CN 116706253 A CN116706253 A CN 116706253A
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- lithium ion
- ion secondary
- secondary battery
- lithium
- battery
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- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 title claims abstract description 106
- 229910001416 lithium ion Inorganic materials 0.000 title claims abstract description 106
- 238000002347 injection Methods 0.000 claims abstract description 40
- 239000007924 injection Substances 0.000 claims abstract description 40
- 239000007788 liquid Substances 0.000 claims abstract description 29
- 239000003792 electrolyte Substances 0.000 claims abstract description 24
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 9
- 239000007773 negative electrode material Substances 0.000 claims description 8
- -1 polyethylene Polymers 0.000 claims description 7
- 239000007774 positive electrode material Substances 0.000 claims description 7
- 238000000926 separation method Methods 0.000 claims description 7
- 238000004804 winding Methods 0.000 claims description 7
- 229910003002 lithium salt Inorganic materials 0.000 claims description 6
- 159000000002 lithium salts Chemical class 0.000 claims description 6
- 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
- 229910052799 carbon Inorganic materials 0.000 claims description 5
- JBTWLSYIZRCDFO-UHFFFAOYSA-N ethyl methyl carbonate Chemical compound CCOC(=O)OC JBTWLSYIZRCDFO-UHFFFAOYSA-N 0.000 claims description 5
- 238000010030 laminating Methods 0.000 claims description 5
- 239000002904 solvent Substances 0.000 claims description 5
- 239000002033 PVDF binder Substances 0.000 claims description 4
- 239000004743 Polypropylene Substances 0.000 claims description 4
- 229910002804 graphite Inorganic materials 0.000 claims description 4
- 239000010439 graphite Substances 0.000 claims description 4
- 229920001155 polypropylene Polymers 0.000 claims description 4
- 229920002981 polyvinylidene fluoride Polymers 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
- 229910001290 LiPF6 Inorganic materials 0.000 claims description 3
- 229910000572 Lithium Nickel Cobalt Manganese Oxide (NCM) Inorganic materials 0.000 claims description 3
- 239000004698 Polyethylene Substances 0.000 claims description 3
- FBDMTTNVIIVBKI-UHFFFAOYSA-N [O-2].[Mn+2].[Co+2].[Ni+2].[Li+] Chemical compound [O-2].[Mn+2].[Co+2].[Ni+2].[Li+] FBDMTTNVIIVBKI-UHFFFAOYSA-N 0.000 claims description 3
- NDPGDHBNXZOBJS-UHFFFAOYSA-N aluminum lithium cobalt(2+) nickel(2+) oxygen(2-) Chemical compound [Li+].[O--].[O--].[O--].[O--].[Al+3].[Co++].[Ni++] NDPGDHBNXZOBJS-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
- 229910021385 hard carbon Inorganic materials 0.000 claims description 3
- 229910000625 lithium cobalt oxide Inorganic materials 0.000 claims description 3
- 229910002102 lithium manganese oxide Inorganic materials 0.000 claims description 3
- BFZPBUKRYWOWDV-UHFFFAOYSA-N lithium;oxido(oxo)cobalt Chemical compound [Li+].[O-][Co]=O BFZPBUKRYWOWDV-UHFFFAOYSA-N 0.000 claims description 3
- VLXXBCXTUVRROQ-UHFFFAOYSA-N lithium;oxido-oxo-(oxomanganiooxy)manganese Chemical compound [Li+].[O-][Mn](=O)O[Mn]=O VLXXBCXTUVRROQ-UHFFFAOYSA-N 0.000 claims description 3
- URIIGZKXFBNRAU-UHFFFAOYSA-N lithium;oxonickel Chemical compound [Li].[Ni]=O URIIGZKXFBNRAU-UHFFFAOYSA-N 0.000 claims description 3
- 239000004005 microsphere Substances 0.000 claims description 3
- 239000004745 nonwoven fabric Substances 0.000 claims description 3
- 229920000573 polyethylene Polymers 0.000 claims description 3
- RUOJZAUFBMNUDX-UHFFFAOYSA-N propylene carbonate Chemical compound CC1COC(=O)O1 RUOJZAUFBMNUDX-UHFFFAOYSA-N 0.000 claims description 3
- 239000002210 silicon-based material Substances 0.000 claims description 3
- 229910021384 soft carbon Inorganic materials 0.000 claims description 3
- 230000000052 comparative effect Effects 0.000 description 38
- 238000002360 preparation method Methods 0.000 description 22
- 229910052744 lithium Inorganic materials 0.000 description 12
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 11
- 229910052782 aluminium Inorganic materials 0.000 description 7
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical group [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 7
- 238000002156 mixing Methods 0.000 description 6
- 239000011267 electrode slurry Substances 0.000 description 4
- 239000011888 foil Substances 0.000 description 4
- 239000000463 material Substances 0.000 description 4
- 238000012360 testing method Methods 0.000 description 4
- 239000013543 active substance Substances 0.000 description 3
- 239000011230 binding agent Substances 0.000 description 3
- 239000006258 conductive agent Substances 0.000 description 3
- 238000001035 drying Methods 0.000 description 3
- 238000000034 method Methods 0.000 description 3
- 239000012046 mixed solvent Substances 0.000 description 3
- 238000011056 performance test Methods 0.000 description 3
- 238000001556 precipitation Methods 0.000 description 3
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical group [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 2
- 229910013870 LiPF 6 Inorganic materials 0.000 description 2
- 230000005540 biological transmission Effects 0.000 description 2
- 239000011248 coating agent Substances 0.000 description 2
- 238000000576 coating method Methods 0.000 description 2
- 239000011889 copper foil Substances 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 238000007599 discharging Methods 0.000 description 2
- 150000002500 ions Chemical class 0.000 description 2
- 238000003825 pressing Methods 0.000 description 2
- 238000003756 stirring Methods 0.000 description 2
- 229910013716 LiNi Inorganic materials 0.000 description 1
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 1
- 239000010405 anode material Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 239000008367 deionised water Substances 0.000 description 1
- 229910021641 deionized water Inorganic materials 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 239000008151 electrolyte solution Substances 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 238000002955 isolation Methods 0.000 description 1
- 238000003475 lamination Methods 0.000 description 1
- 229910003473 lithium bis(trifluoromethanesulfonyl)imide Inorganic materials 0.000 description 1
- 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 1
- 239000011572 manganese Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000003921 oil Substances 0.000 description 1
- 238000004806 packaging method and process Methods 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 238000007493 shaping process Methods 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
- 238000009461 vacuum packaging Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
- 238000005303 weighing Methods 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/058—Construction or manufacture
-
- 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
- H01M2220/00—Batteries for particular applications
- H01M2220/20—Batteries in motive systems, e.g. vehicle, ship, plane
-
- 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
Abstract
The application discloses a lithium ion secondary battery, and relates to the technical field of batteries. The lithium ion secondary battery satisfies the following conditions: a is more than or equal to 86% and less than or equal to 91%, b is more than or equal to 1.5 and less than or equal to 3,1.06, c is more than or equal to 1.14; and satisfies the following formula: 5.9 < ((100 a-88) 2 +3.5)/b 2 (c-1.02) < 23, wherein a is a shell group entering margin, and the shell group entering margin is the ratio of the thickness or the diameter of the battery cell to the thickness or the diameter of the shell; b is a liquid injection coefficient, wherein the liquid injection coefficient is the ratio of the mass of electrolyte to the capacity of the battery cell, and the unit is g/Ah; c is a CB value which is the ratio of the capacity of the negative electrode per unit area to the capacity of the positive electrode per unit area. When the shell group entering margin, the liquid injection coefficient and the CB value of the lithium ion secondary battery meet the value range and the formula, the lithium ion secondary battery can have high energy density and high power performance on the premise of ensuring the cycle life.
Description
Technical Field
The application relates to the technical field of batteries, in particular to a lithium ion secondary battery.
Background
With the development of modern society and the progress of science and technology, automobiles become the mainstream tool of riding instead of walk gradually, and with the increase of automobile quantity, traffic is crowded gradually, and vertical take-off and landing equipment moves into people's field of vision gradually. The annual increase in oil prices has also led to electrically driven vertical take-off and landing equipment (Electric Vertical Takeoff and Landing, EVTOL) as a technological pursuit target. Lithium ion secondary batteries are currently the best choice in EVTOL driving. Because of the uniqueness of EVTOL, there is a demand for lithium ion secondary batteries that combine high energy density, high power and long life.
In view of this, providing a lithium ion secondary battery with energy density while continuously providing high power output under the premise of ensuring battery cycle life is a necessary condition for promoting the development of the spacecraft industry.
Disclosure of Invention
The application aims to solve the technical problem of providing a lithium ion secondary battery with high energy density, high power and long service life, and the prepared lithium ion secondary battery can have the performance of high energy density and high power on the premise of ensuring the cycle life of a battery core by controlling the shell group entering margin, the liquid injection coefficient and the CB value of the lithium ion secondary battery.
In order to solve the technical problems, the application provides the following technical scheme:
the first aspect of the application provides a lithium ion secondary battery, which comprises a shell, a battery core arranged in a cavity in the shell and electrolyte filled in the cavity in the shell, wherein the lithium ion secondary battery meets the following conditions: a is more than or equal to 86% and less than or equal to 91%, b is more than or equal to 1.5 and less than or equal to 3,1.06, c is more than or equal to 1.14;
and satisfies the following formula: 5.9 < ((100 a-88) 2 +3.5)/b 2 (c-1.02)﹤23；
Wherein a is a shell entering group margin, and the shell entering group margin is the ratio of the thickness or the diameter of the battery core to the thickness or the diameter of the cavity in the shell;
b is a liquid injection coefficient, wherein the liquid injection coefficient is the ratio of the mass of electrolyte to the capacity of the battery cell, and the unit is g/Ah;
c is a CB value which is the ratio of the capacity of the negative electrode per unit area to the capacity of the positive electrode per unit area.
Further, the shell group entering margin of the lithium ion secondary battery is more preferably 87% or more and 90% or less.
Further, the liquid injection coefficient of the lithium ion secondary battery is more than or equal to 1.8 and less than or equal to 2.4.
Further, the CB value of the lithium ion secondary battery is more than or equal to 1.08 and less than or equal to 1.12.
Further, the lithiumMore preferably, the ion secondary battery satisfies the following formula: 7 < ((100 a-88) 2 +3.5)/b 2 (c-1.02)﹤18。
Further, the battery cell is prepared by laminating an anode plate, a separation film and a cathode plate in a lamination manner or a winding manner.
Further, the positive electrode sheet comprises a positive electrode current collector and a positive electrode active layer which is arranged on the positive electrode current collector and contains a positive electrode active substance; wherein the positive electrode current collector is preferably aluminum foil or carbon-coated aluminum foil, and the positive electrode active material is preferably one or more of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel cobalt manganese oxide and lithium nickel cobalt aluminum oxide.
Further, the material of the isolation film is preferably a polyethylene film, a polypropylene film, a polyvinylidene fluoride film or a non-woven fabric.
Further, the negative electrode tab includes a negative electrode current collector and a negative electrode active layer including a negative electrode active material disposed on the negative electrode current collector; the negative electrode current collector is preferably copper foil, and the negative electrode active material is preferably one or more of graphite, soft carbon, hard carbon, mesophase carbon microspheres and silicon-based materials.
Further, the electrolyte comprises a lithium salt and a solvent, wherein the lithium salt is selected from one or more of LiPF6, liBF4 and LiTFSI, and the solvent is selected from one or more of ethylene carbonate, propylene carbonate, butylene carbonate, methyl ethyl carbonate, dimethyl carbonate and diethyl carbonate.
Compared with the prior art, the application has the beneficial effects that:
the application provides a lithium ion secondary battery, which is characterized in that the shell group entering margin, the liquid injection coefficient and the CB value of the lithium ion secondary battery are reasonably designed, and the three satisfy a specific relation 5.9 ((100 a-88) 2 +3.5)/b 2 (C-1.02) is less than 23, and the lithium ion secondary battery has high energy density (not less than 254 Wh/Kg) under the premise of ensuring long cycle life (the battery capacity is 80% of the initial capacity at normal temperature of 1C/1C and the corresponding cycle number is not less than 850 cycles)And high power performance (DCR no higher than 1.31 m Ω).
Detailed Description
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the description of the application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and/or" as used herein includes any and all combinations of one or more of the associated listed items. The term "comprising" or "comprises" as used herein means that it may include or comprise other components in addition to the components described. The term "comprising" or "comprising" as used herein may also be replaced by "being" or "consisting of" closed.
Based on the demand for a lithium ion secondary battery with high energy density, high power and long service life, the application provides a lithium ion secondary battery, which comprises a shell, a battery core arranged in a cavity in the shell and electrolyte filled in the cavity in the shell, wherein the lithium ion secondary battery meets the following conditions: a is more than or equal to 86% and less than or equal to 91%, b is more than or equal to 1.5 and less than or equal to 3,1.06, c is more than or equal to 1.14; and the following formulas are satisfied among a, b and c: 5.9 < ((100 a-88) 2 +3.5)/b 2 (c-1.02)﹤23。
Wherein a is a shell entering group margin, and the shell entering group margin is the ratio of the thickness or the diameter of the battery core to the thickness or the diameter of the cavity in the shell; b is a liquid injection coefficient, wherein the liquid injection coefficient is the ratio of the mass of electrolyte to the capacity of the battery cell, and the unit is g/Ah; c is a CB value which is the ratio of the capacity of the negative electrode per unit area to the capacity of the positive electrode per unit area.
In some preferred embodiments of the present application, the value range of the in-shell group margin of the lithium ion secondary battery is preferably 86% to 91%, wherein the value of a is any one of 86%, 86.3%, 86.5%, 86.8%, 87%, 87.5%, 88%, 88.3%, 88.5%, 89%, 89.5%, 90%, 90.5%, 91%, but not limited to the above-listed values; specifically, when the lithium ion secondary battery is cylindrical, and the battery core is prepared by a winding mode, the shell group entering margin is the ratio of the diameter of the battery core to the diameter of the cavity in the shell; when the lithium ion secondary battery is square, and the battery core is prepared by winding or laminating, the shell group entering margin is the ratio of the thickness of the battery core to the thickness of the cavity in the shell. The design of the margin size of the shell entering group not only can determine the difficulty degree of the shell entering of the battery core, but also can influence the capacity of the battery, in addition, the anode material of the lithium ion secondary battery can expand when being charged, and the service life of the battery core can be influenced by the interaction force between the expanded battery core and the aluminum shell, so that the margin size of the shell entering group can also influence the performances such as the energy density, the service life and the like of the lithium battery.
Specifically, if the margin of the shell entering group is too small, the battery core is easy to enter the shell, but the energy density of the battery is relatively low, and because a large enough space exists between the battery core and the shell, the battery core which expands due to charging is not extruded by the aluminum shell, so that the situation that the pole pieces are easy to expand in disorder is caused, the contact of the positive pole piece and the negative pole piece is easy to be poor, and the anode piece is black; however, if the margin of the shell entering group is too large, the energy density of the battery is relatively high, but the difficulty of the shell entering of the battery core is increased, the battery core is easy to damage in the process of the shell entering of the battery core, in addition, the battery core expands after being charged, the top and the bottom of the battery core are extruded by the aluminum shell, uneven stress of the pole piece can be caused, and the problem of lithium precipitation is easy to occur in a severely stressed area, so that the service life of the battery is influenced. Therefore, the shell group entering margin is required to be controlled within a proper range, namely 86 percent is more than or equal to a and less than or equal to 91 percent, so that the lithium ion secondary battery has the performances of long service life, high energy density and the like.
In some preferred embodiments, the range of values for the population entering margin of the lithium ion secondary battery is more preferably 87% +.a.ltoreq.90%, e.g., a is 87%, 87.3%, 87.5%, 87.7%, 88%, 88.3%, 88.5%, 89%, 89.2%, 89.5%, 89.8%, 90%, etc., including but not limited to the values described above.
In addition, in some preferred embodiments of the present application, the value range of the injection coefficient of the lithium ion secondary battery is preferably 1.5.ltoreq.b.ltoreq.3 g/Ah, wherein the value of b is any one of 1.6, 1.7, 1.8, 1.9, 2.1, 2.2, 2.5, 2.8; the relative content of the electrolyte in the battery is determined by the size of the electrolyte injection coefficient, and the content of the electrolyte serving as a transmission medium of lithium ions in the charging and discharging processes of the battery core directly influences the capacity, the cycle performance and the power performance of the battery.
Specifically, if the liquid injection coefficient is too small, i.e. the content of electrolyte in the battery is small, the positive pole piece and the diaphragm in the battery cannot be completely wetted by the electrolyte, and active substances cannot be fully utilized, so that the internal resistance of the battery core is large and the capacity is low; in addition, the battery cell with high internal resistance generates large heat, and decomposition or volatilization of electrolyte can be further accelerated, so that the cycle performance of the battery can be reduced, and meanwhile, under the condition that the electrolyte is insufficient, the carrying capacity of lithium ions is reduced, the lithium ions can be separated out on the surface of a negative electrode, so that a lithium separation phenomenon is caused, and when the lithium separation amount reaches a certain degree, lithium metal pierces through a diaphragm, so that the positive electrode and the negative electrode are short-circuited, and the battery cell is further caused to fire and explode. However, if the injection coefficient is too large, the electrolyte content is too much, which is favorable for the transmission of lithium ions, but too much electrolyte limits the volume of the battery core in the shell, thereby affecting the energy density of the battery, and too much electrolyte can cause side reaction and increase of gas yield, on one hand, the cycle performance of the battery can be reduced, and in addition, a large amount of gas yield can increase the internal pressure of the battery, which is easy to cause the problems of shell rupture, electrolyte leakage and the like. Therefore, the liquid injection coefficient is required to be controlled within a proper range, namely b is more than or equal to 1.5 and less than or equal to 3 g/Ah, so that the energy density and the power performance of the battery are balanced on the premise of ensuring the cycle performance of the battery.
In some preferred embodiments, the value of the injection coefficient of the lithium ion secondary battery is more preferably 1.8.ltoreq.b.ltoreq.2.4 g/Ah, for example, b is 1.8 g/Ah, 1.9 g/Ah, 2.0 g/Ah, 2.1 g/Ah, 2.2 g/Ah, 2.3 g/Ah, 2.4 g/Ah, etc., including but not limited to the values described above.
In some preferred embodiments, the CB value of the lithium ion secondary battery is preferably 1.06 c.ltoreq.1.14, and when the CB value is too large, the capacity of the negative electrode plate unit area of the battery core is relatively large, which can reduce the risk of lithium precipitation during quick charge, thereby increasing the quick charge capacity of the battery core; however, the CB value is increased, the surface density of the positive electrode sheet is relatively low, resulting in a decrease in the capacity of the battery core, thereby decreasing the energy density of the battery core. However, if the CB value is too low, the energy density and cycle performance of the battery cell can be improved to some extent, but the lithium precipitation risk during the quick charging of the battery cell is increased, and a certain safety risk is provided.
More preferably, the CB value of the lithium ion secondary battery is in the range of 1.08.ltoreq.c.ltoreq.1.12, for example, c is 1.08, 1.09, 1.1, 1.11, 1.12, etc., including but not limited to the above values.
The inventors found that the shell group entering margin, the liquid injection coefficient and the CB value of the lithium ion secondary battery have influence on the energy density, the power performance and the cycle life of the battery core, and the three are interrelated. The application can improve the energy density, the power performance or the cycle performance of the lithium ion secondary battery to a certain extent by optimizing the shell group entering margin, the liquid injection coefficient or the CB value of the ion secondary battery, but has larger limitation on improving the energy density, the power performance and the cycle performance simultaneously due to each factor, namely, the size of each factor is different from the logical positive-negative correlation between the energy density and the power performance of the battery core, for example, the energy density of the battery core is increased along with the increase of the value a (in the preferred value range), but b and c are both reduced along with the increase of the value in the preferred value range, and the power performance is improved (DCR value is smaller); on the premise of meeting the logical positive-negative correlation between the size of each factor and the energy density and power performance of the battery cell, the factors (a, b and c) have different influences on the energy density and the power performance, so that the factors (a, b and c) cannot take any value in the preferred value ranges.
In order to balance the influence of each factor (a, b, c) on energy density and power performance and achieve the aim of mutual cooperation among the factors (a, b, c), the application proposes that when the parameters are in a proper range, the formula 5.9 ((100 a-88) is satisfied 2 +3.5)/b 2 When (c-1.02) is less than 23, the lithium ion secondary battery can have both high energy density and high energy density while maintaining a long lifeHigh power performance.
In some preferred embodiments, the lithium ion secondary battery more preferably satisfies the following formula: 7 < ((100 a-88) 2 +3.5)/b 2 (c-1.02) < 18; illustratively, ((100 a-88) 2 +3.5)/b 2 (c-1.02) may have a value in the range of 8 to 17. Illustratively, when a is 88%, b is 2.2, and c is 1.1, ((100 a-88) 2 +3.5)/b 2 (c-1.02) was 9.
In some preferred embodiments, the battery cell is prepared by stacking a positive electrode plate, a separation film and a negative electrode plate, and laminating or winding the positive electrode plate, the separation film and the negative electrode plate.
Specifically, the positive electrode plate comprises a positive electrode current collector and a positive electrode active layer which is arranged on the positive electrode current collector and contains a positive electrode active substance; the positive electrode current collector can be aluminum foil or carbon-coated aluminum foil, and the positive electrode active material is preferably one or more of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel cobalt manganese oxide and lithium nickel cobalt aluminum oxide, but the application is not limited to these materials, and other known positive electrode active materials of lithium ion secondary batteries can be used; the positive electrode active material is, for example, NCM8 positive electrode active material.
In some preferred embodiments, the separator may be a polyethylene film, a polypropylene film, a polyvinylidene fluoride film, or a nonwoven fabric, and other separator materials that can be used for lithium ion secondary batteries may be used.
In some preferred embodiments, the negative electrode tab includes a negative electrode current collector and a negative electrode active layer including a negative electrode active material disposed on the negative electrode current collector; the negative electrode current collector is preferably copper foil, and the negative electrode active material is preferably one or more of graphite, soft carbon, hard carbon, mesophase carbon microspheres, and silicon-based materials, but the present application is not limited to these materials, and other known negative electrode active materials for lithium ion secondary batteries may be used.
In some preferred embodiments, the electrolyte includes a lithium salt and a solvent, wherein the lithium salt may be LiPF6, liBF4, liTFSI, etc., and the solvent may be selected from a mixed solvent of several of ethylene carbonate, propylene carbonate, butylene carbonate, methylethyl carbonate, dimethyl carbonate, diethyl carbonate, for example, a mixed solvent of ethylene carbonate, methylethyl carbonate, diethyl carbonate in a volume ratio of 1:1:1.
The present application will be further described with reference to examples, which are not intended to be limiting, so that those skilled in the art will better understand the present application and practice it.
Example 1
The embodiment relates to a preparation method of a lithium ion secondary battery, which specifically comprises the following steps:
preparing a positive electrode plate: the positive electrode active material LiNi 0.83 Co 0.12 Mn 0.05 O 2 Mixing the conductive agent SP and the binder PVDF in a mass ratio of 95.5:3.5:1, adding NMP, stirring to obtain uniformly mixed positive electrode slurry, uniformly coating the positive electrode slurry on a positive electrode current collector, drying, and cold pressing to obtain a positive electrode plate; the surface density of the positive pole piece is 146 g/m 2 ；
Preparing a negative electrode plate: mixing a negative electrode active material, a conductive agent and a binder in a mass ratio of 95.1:1.6:3.3, mixing graphite and silicon oxide in a mass ratio of 81:19 to obtain a negative electrode active material, mixing SP and CNT in a mass ratio of 1:1 to obtain a conductive agent, mixing PAA and SBR in a mass ratio of 1:1 to obtain a binder, adding deionized water, stirring to obtain uniformly mixed negative electrode slurry, coating the negative electrode slurry on a negative electrode current collector, drying and cold pressing to obtain a negative electrode plate; the surface density of the negative pole piece is 57.8 g/m 2 ；
A diaphragm: selecting a commercial polypropylene film with the thickness of 9 mu m;
electrolyte solution: mixing ethylene carbonate, methyl ethyl carbonate and diethyl carbonate in the volume ratio of 1:1:1 to obtain a mixed solvent, and adding lithium salt LiPF 6 Configuration to obtain LiPF 6 Electrolyte with the concentration of 1.2 mol/L;
assembling a lithium ion secondary battery: laminating the positive electrode plate, the diaphragm and the negative electrode plate, and forming a bare cell in a winding mode; the bare cell is placed in an outer packaging shell (model 2614897), and electrolyte is injected after drying, and the lithium ion secondary battery is obtained through the procedures of vacuum packaging, standing, formation, shaping and the like.
The lithium ion secondary battery prepared in the embodiment has a shell group entering margin of 88%, a liquid injection coefficient of 2.2 and a CB value of 1.1; in the following examples and comparative examples, the shell group entering margin, the liquid injection coefficient and the CB value of the lithium ion secondary battery were controlled by adjusting one or more parameters of the number of winding layers, the injection amount of the electrolyte and the surface density of the negative electrode sheet.
Example 2
This example relates to the preparation of a lithium ion secondary battery, which differs from example 1 in that: the shell group entering margin is 89%, the liquid injection coefficient is 2.1, and the CB value is 1.08.
Example 3
This example relates to the preparation of a lithium ion secondary battery, which differs from example 1 only in that: the shell group entering margin is 86%.
Example 4
This example relates to the preparation of a lithium ion secondary battery, which differs from example 1 only in that: the shell group entering margin is 87%.
Example 5
This example relates to the preparation of a lithium ion secondary battery, which differs from example 1 only in that: the margin for the shell group is 89%.
Example 6
This example relates to the preparation of a lithium ion secondary battery, which differs from example 1 only in that: the shell group entering margin is 90%.
Example 7
This example relates to the preparation of a lithium ion secondary battery, which differs from example 1 only in that: the injection coefficient is 1.5.
Example 8
This example relates to the preparation of a lithium ion secondary battery, which differs from example 1 only in that: the injection coefficient is 1.8.
Example 9
This example relates to the preparation of a lithium ion secondary battery, which differs from example 1 only in that: the liquid injection coefficient is 2.4.
Example 10
This example relates to the preparation of a lithium ion secondary battery, which differs from example 1 in that: the CB value is 1.06.
Example 11
This example relates to the preparation of a lithium ion secondary battery, which differs from example 1 in that: the CB value was 1.08.
Example 12
This example relates to the preparation of a lithium ion secondary battery, which differs from example 1 in that: the CB value is 1.12.
Example 13
This example relates to the preparation of a lithium ion secondary battery, which differs from example 1 in that: the CB value is 1.14.
Comparative example 1
This comparative example relates to the preparation of a lithium ion secondary battery, which is different from example 1 in that: the shell group entering margin is 84%.
Comparative example 2
This comparative example relates to the preparation of a lithium ion secondary battery, which is different from example 1 in that: the margin for the intrusion into the shell group was 94%.
Comparative example 3
This comparative example relates to the preparation of a lithium ion secondary battery, which is different from example 1 in that: the injection coefficient is 1.3.
Comparative example 4
This comparative example relates to the preparation of a lithium ion secondary battery, which is different from example 1 in that: the injection coefficient is 3.3.
Comparative example 5
This comparative example relates to the preparation of a lithium ion secondary battery, which is different from example 1 in that: the CB value is 1.04.
Comparative example 6
This comparative example relates to the preparation of a lithium ion secondary battery, which is different from example 1 in that: the CB value is 1.16.
Comparative example 7
This comparative example relates to the preparation of a lithium ion secondary battery, which differs from example 1 only in that: the liquid injection coefficient is 3.
Comparative example 8
This comparative example relates to the preparation of a lithium ion secondary battery, which is different from example 1 in that: the liquid injection coefficient is 2.5, and the CB value is 1.14.
Comparative example 9
This comparative example relates to the preparation of a lithium ion secondary battery, which is different from example 6 in that: the liquid injection coefficient is 2, and the CB value is 1.09.
Performance testing
The cycle life, energy density and DCR performance of the lithium ion secondary batteries prepared in the above examples and comparative examples were tested as follows:
cycle life test: the lithium ion secondary batteries prepared in examples and comparative examples were subjected to full charge discharge cycle test under 1C charge/1C discharge conditions at 25C until the capacity fade value of the lithium ion secondary battery was 80% of the initial capacity, and the number of cycles was recorded.
Energy density testing: and (3) fully charging the lithium ion secondary batteries prepared in the examples and the comparative examples at the rate of 1C at the temperature of 25 ℃, fully discharging at the rate of 1C, and recording the actual discharge energy, wherein the ratio of the actual discharge energy to the weight (weighing at the temperature of 25 ℃) of the lithium ion secondary battery is the actual energy density of the lithium ion secondary battery.
DCR performance test: the lithium ion secondary batteries prepared in the examples and the comparative examples are fully charged at a constant current and constant voltage at 25 ℃ with a current of 1C, are left for 5 min, are discharged at a constant current of 1C for 30 min, are left for 5 min, take a voltage value V1 at the end of the standing, are discharged at a pulse of 2C for 30 s, and take a ratio of a voltage difference value between V1 and V2 and a current value of 2C at the end of the pulse discharge as the DCR of 50% SOC discharge of the battery.
The results of the above performance tests are shown in table 1 below:
TABLE 1
As is clear from the data of examples 1 to 13 and comparative examples 1 to 8 in the above tables, when the lithium ion secondary battery has a case group margin of 86% or more and 91% or less, a liquid injection coefficient of 1.5% or less and 3% or less and a CB value of 1.06% or less and 1.14% or less, the 5.9% or less ((100 a-88) is satisfied 2 +3.5)/b 2 When (c-1.02) is less than 23, the battery has long cycle life, high energy density and high power performance under the condition of high-rate charge and discharge. While ((100 a-88) 2 +3.5)/b 2 (c-1.02)>23 or ((100 a-88) 2 +3.5)/b 2 (c-1.02)<5.3, the battery cannot simultaneously give consideration to cycle life, energy density and power performance. In addition, as is clear from the above examples, when the lithium ion secondary battery is 87% or more and the shell group margin is 89% or less, the liquid injection coefficient is 1.8% or less and 2.4% or less and the CB value is 1.06% or less and 1.14% or less, and 7 < ((100 a-88) is satisfied 2 +3.5)/b 2 When (c-1.02) is less than 18, the overall performance of the battery is better.
As is clear from examples 1 and comparative examples 1 and 2, too small a margin value of the battery pack (comparative example 1) or too large a margin value of the battery pack (comparative example 2) affects the cycle life and power performance of the lithium ion battery, and especially when the margin value of the battery pack is too large, the battery is charged and discharged for about 400 cycles only, the capacity is reduced by 80% of the initial capacity, and the DCR value is increased to 1.63, and the power performance is poor. And comparative examples 1, 2 are represented by the relationship ((100 a-88) 2 +3.5)/b 2 The values calculated in (c-1.02) were not in the range of 5.3 to 23, and the larger the value deviated from this interval, the worse the overall performance of the battery was.
As can be seen from example 1 and comparative examples 3 and 4, the liquid injection coefficient of the lithium ion battery cannot be too small, while the lithium battery prepared in comparative example 3 has higher energy density, but the cycle performance and the power performance are poor, the battery capacity is reduced by 80% of the initial capacity after only about 300 cycles of charge and discharge, and the DCR value is as high as 1.86; however, the injection coefficient was not excessively large, and the lithium ion battery prepared in comparative example 4 had an injection coefficient of 3.3, and the battery had a low DCR value but a significantly reduced energy density of only 238 Wh/Kg and a somewhat reduced cycle performance, as compared with example 1. In addition, when the energy density of the battery is too low, the DCR value is too large or the cycle life is low, the overall performance of the battery is poor, and the relationship ((100 a-88) is used at this time 2 +3.5)/b 2 (c-1.02) is not between 5.3 and 23.
As is clear from examples 1 and comparative examples 5 and 6, the CB value of the lithium-ion battery cannot be too small, and the comparative example 5 prepared lithium-ion battery with a larger CB value has a relatively higher energy density and a low DCR value, but the cycle performance is only half that of example 1; meanwhile, the CB value of the lithium ion battery cannot be too large, the CB value of the lithium ion battery prepared in the comparative example 5 is 1.16, and various performances of the lithium ion battery are reduced compared with those of the lithium ion battery prepared in the example 1.
As is clear from comparative examples 7 and 8, the lithium battery has a shell group margin, a liquid injection coefficient and a CB value within the preferable ranges, but ((100 a-88) 2 +3.5)/b 2 The calculated value of (c-1.02) is 4.7, the preferable value range is not satisfied, and the energy density, the cycle performance and the DCR value of the lithium battery are tested, so that the energy density of the lithium battery prepared by comparative examples 7 and 8 is lower and the comprehensive performance is poor as shown in the table 1. Further, as is clear from examples 6 and 9, the values of the parameters a, b and c in examples 6 and 9 are within the preferable ranges, and the values of the parameters b and c are different, and as is clear from the above-mentioned performance test results, the overall performance of the lithium battery constructed in example 6 is superior to that of comparative example 9, wherein example 6 is represented by the relation ((100 a-88) 2 +3.5)/b 2 The value calculated in (c-1.02) was 19.4 falling within the preferred range of the relationship, whereas comparative example 9 calculated from the above relationship was 26.8, which is outside the maximum value of the preferred range.
In summary, in order to make the lithium ion secondary battery have long cycle life, high energy density and high power performance while maintaining long cycle life, it is necessary to optimize the battery's shell group margin a, liquid injection coefficient b and CB value c at the same time, and to make the above parameters satisfy the formula 5.9 < ((100 a-88) 2 +3.5)/b 2 When (c-1.02) is less than 23, the secondary battery including lithium ions can have a long cycle life, a high energy density, and high power performance.
The above-described embodiments are merely preferred embodiments for fully explaining the present application, and the scope of the present application is not limited thereto. Equivalent substitutions and modifications will occur to those skilled in the art based on the present application, and are intended to be within the scope of the present application. The protection scope of the application is subject to the claims.
Claims (10)
1. The utility model provides a lithium ion secondary battery, includes casing, set up in electric core in the casing cavity and fill in electrolyte in the casing cavity, its characterized in that:
the lithium ion secondary battery satisfies:
86%≤a≤91%，1.5≤b≤3，1.06≤c≤1.14；
and satisfies the following formula: 5.9 < ((100 a-88) 2 +3.5)/b 2 (c-1.02)﹤23；
Wherein a is a shell entering group margin, and the shell entering group margin is the ratio of the thickness or the diameter of the battery core to the thickness or the diameter of the cavity in the shell;
b is a liquid injection coefficient, wherein the liquid injection coefficient is the ratio of the mass of electrolyte to the capacity of the battery cell, and the unit is g/Ah;
c is a CB value which is the ratio of the capacity of the negative electrode per unit area to the capacity of the positive electrode per unit area.
2. The lithium ion secondary battery according to claim 1, wherein the lithium ion secondary battery has a shell group inclusion margin of 87% or more and 90% or less.
3. The lithium ion secondary battery according to claim 1, wherein the liquid injection coefficient of the lithium ion secondary battery is 1.8.ltoreq.b.ltoreq.2.4.
4. The lithium ion secondary battery according to claim 1, wherein the CB value of the lithium ion secondary battery is 1.08.ltoreq.c.ltoreq.1.12.
5. The lithium ion secondary battery according to claim 1, wherein the lithium ion secondary battery satisfies the following formula: 7 < ((100 a-88) 2 +3.5)/b 2 (c-1.02)﹤18。
6. The lithium ion secondary battery according to claim 1, wherein the battery cell is prepared by stacking a positive electrode plate, a separation film and a negative electrode plate, and laminating or winding the positive electrode plate, the separation film and the negative electrode plate.
7. The lithium ion secondary battery according to claim 6, wherein the positive electrode sheet contains a positive electrode active material selected from one or more of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel cobalt manganese oxide, and lithium nickel cobalt aluminum oxide.
8. The lithium ion secondary battery according to claim 6, wherein the negative electrode sheet contains a negative electrode active material selected from one or more of graphite, soft carbon, hard carbon, mesophase carbon microspheres, and silicon-based materials.
9. The lithium ion secondary battery according to claim 6, wherein the separator is made of a polyethylene film, a polypropylene film, a polyvinylidene fluoride film or a nonwoven fabric.
10. The lithium ion secondary battery according to claim 1, wherein the electrolyte comprises a lithium salt selected from one or more of LiPF6, liBF4, liTFSI, and a solvent selected from one or more of ethylene carbonate, propylene carbonate, butylene carbonate, methylethyl carbonate, dimethyl carbonate, diethyl carbonate.
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| CN105047986A (en) * | 2015-07-04 | 2015-11-11 | 广东烛光新能源科技有限公司 | Electrochemical energy storage device and preparation method hereof |
| CN111628218A (en) * | 2020-05-18 | 2020-09-04 | 珠海冠宇电池股份有限公司 | Lithium ion battery and preparation method thereof |
| CN216354449U (en) * | 2021-11-16 | 2022-04-19 | 宁德时代新能源科技股份有限公司 | Battery case, battery monomer, battery and power consumption device |
| CN116014077A (en) * | 2023-03-27 | 2023-04-25 | 江苏正力新能电池技术有限公司 | Lithium ion battery negative electrode plate and lithium ion battery |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN105047986A (en) * | 2015-07-04 | 2015-11-11 | 广东烛光新能源科技有限公司 | Electrochemical energy storage device and preparation method hereof |
| CN111628218A (en) * | 2020-05-18 | 2020-09-04 | 珠海冠宇电池股份有限公司 | Lithium ion battery and preparation method thereof |
| CN216354449U (en) * | 2021-11-16 | 2022-04-19 | 宁德时代新能源科技股份有限公司 | Battery case, battery monomer, battery and power consumption device |
| CN116014077A (en) * | 2023-03-27 | 2023-04-25 | 江苏正力新能电池技术有限公司 | Lithium ion battery negative electrode plate and lithium ion battery |
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