CN116936745A - Lithium ion battery and preparation method thereof - Google Patents
Lithium ion battery and preparation method thereof Download PDFInfo
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- CN116936745A CN116936745A CN202310844108.8A CN202310844108A CN116936745A CN 116936745 A CN116936745 A CN 116936745A CN 202310844108 A CN202310844108 A CN 202310844108A CN 116936745 A CN116936745 A CN 116936745A
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- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 title claims abstract description 41
- 229910001416 lithium ion Inorganic materials 0.000 title claims abstract description 41
- 238000002360 preparation method Methods 0.000 title abstract description 9
- 239000007774 positive electrode material Substances 0.000 claims abstract description 66
- 239000000463 material Substances 0.000 claims abstract description 51
- DVATZODUVBMYHN-UHFFFAOYSA-K lithium;iron(2+);manganese(2+);phosphate Chemical compound [Li+].[Mn+2].[Fe+2].[O-]P([O-])([O-])=O DVATZODUVBMYHN-UHFFFAOYSA-K 0.000 claims abstract description 38
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 claims abstract description 35
- 229910052744 lithium Inorganic materials 0.000 claims abstract description 35
- 239000011572 manganese Substances 0.000 claims abstract description 18
- 239000013543 active substance Substances 0.000 claims abstract description 13
- 229910052748 manganese Inorganic materials 0.000 claims abstract description 12
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 claims abstract description 10
- 239000011149 active material Substances 0.000 claims description 47
- 238000000034 method Methods 0.000 claims description 35
- 239000007773 negative electrode material Substances 0.000 claims description 16
- 239000000126 substance Substances 0.000 claims description 13
- 239000002245 particle Substances 0.000 claims description 11
- 238000004537 pulping Methods 0.000 claims description 9
- 239000011888 foil Substances 0.000 claims description 7
- 238000005056 compaction Methods 0.000 claims description 6
- 239000011248 coating agent Substances 0.000 claims description 5
- 238000000576 coating method Methods 0.000 claims description 5
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 5
- 229910021383 artificial graphite Inorganic materials 0.000 claims description 4
- 229910021382 natural graphite Inorganic materials 0.000 claims description 4
- 229910015645 LiMn Inorganic materials 0.000 claims description 3
- 229910021385 hard carbon Inorganic materials 0.000 claims description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 2
- 229910015118 LiMO Inorganic materials 0.000 claims description 2
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims description 2
- 229910002804 graphite Inorganic materials 0.000 claims description 2
- 239000010439 graphite Substances 0.000 claims description 2
- 229910052759 nickel Inorganic materials 0.000 claims description 2
- 229910052710 silicon Inorganic materials 0.000 claims description 2
- 239000010703 silicon Substances 0.000 claims description 2
- 230000008901 benefit Effects 0.000 abstract description 3
- GELKBWJHTRAYNV-UHFFFAOYSA-K lithium iron phosphate Chemical compound [Li+].[Fe+2].[O-]P([O-])([O-])=O GELKBWJHTRAYNV-UHFFFAOYSA-K 0.000 abstract description 3
- 230000000052 comparative effect Effects 0.000 description 21
- 230000008569 process Effects 0.000 description 14
- HFCVPDYCRZVZDF-UHFFFAOYSA-N [Li+].[Co+2].[Ni+2].[O-][Mn]([O-])(=O)=O Chemical compound [Li+].[Co+2].[Ni+2].[O-][Mn]([O-])(=O)=O HFCVPDYCRZVZDF-UHFFFAOYSA-N 0.000 description 9
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 6
- 238000013508 migration Methods 0.000 description 6
- 230000005012 migration Effects 0.000 description 6
- 238000012360 testing method Methods 0.000 description 6
- 230000009977 dual effect Effects 0.000 description 5
- PXHVJJICTQNCMI-UHFFFAOYSA-N nickel Substances [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 5
- AWKHTBXFNVGFRX-UHFFFAOYSA-K iron(2+);manganese(2+);phosphate Chemical compound [Mn+2].[Fe+2].[O-]P([O-])([O-])=O AWKHTBXFNVGFRX-UHFFFAOYSA-K 0.000 description 4
- 102220043159 rs587780996 Human genes 0.000 description 4
- 125000004122 cyclic group Chemical group 0.000 description 3
- 230000007774 longterm Effects 0.000 description 3
- 239000000377 silicon dioxide Substances 0.000 description 3
- 230000008859 change Effects 0.000 description 2
- 230000001276 controlling effect Effects 0.000 description 2
- 230000001351 cycling effect Effects 0.000 description 2
- 230000029087 digestion Effects 0.000 description 2
- 238000007599 discharging Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 230000007613 environmental effect Effects 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 238000011056 performance test Methods 0.000 description 2
- 239000011148 porous material Substances 0.000 description 2
- 230000001105 regulatory effect Effects 0.000 description 2
- 230000001360 synchronised effect Effects 0.000 description 2
- 229910015566 LiMn0.4Fe0.6PO4 Inorganic materials 0.000 description 1
- 229910016096 LiMn0.5Fe0.5PO4 Inorganic materials 0.000 description 1
- 239000010405 anode material Substances 0.000 description 1
- 230000033228 biological regulation Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000010406 cathode material Substances 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000009699 differential effect Effects 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000004615 ingredient Substances 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 230000014759 maintenance of location Effects 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000011268 mixed slurry Substances 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000003825 pressing Methods 0.000 description 1
- 230000002035 prolonged effect Effects 0.000 description 1
- 238000004064 recycling Methods 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
Classifications
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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
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
- H01M4/136—Electrodes based on inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy
-
- 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
- H01M10/058—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
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
- H01M4/131—Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
-
- 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
- H01M2004/021—Physical characteristics, e.g. porosity, surface area
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- 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
-
- 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
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
- Y02P70/50—Manufacturing or production processes characterised by the final manufactured product
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- Chemical & Material Sciences (AREA)
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- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Materials Engineering (AREA)
- Manufacturing & Machinery (AREA)
- Inorganic Chemistry (AREA)
- Battery Electrode And Active Subsutance (AREA)
Abstract
The application particularly discloses a lithium ion battery and a preparation method thereof. A lithium ion battery comprising a core pack, wherein the core pack comprises a first pole group and a second pole group; the first electrode group comprises a first positive electrode plate, wherein the active substance layer of the first positive electrode plate comprises a first positive electrode active material, and the first positive electrode active material is a lithium iron manganese phosphate material; the second electrode group comprises a second positive electrode plate, wherein the active substance layer of the second positive electrode plate comprises a second positive electrode active material, and the second positive electrode active material is any one of ternary material and lithium-rich manganese-based material. The application has the advantages of avoiding the sudden increase of the double voltage platform and DCR of the lithium iron phosphate battery and improving the cycle performance of the lithium battery.
Description
Technical Field
The application relates to the technical field of lithium batteries, in particular to a lithium ion battery and a preparation method thereof.
Background
With the continuous development of new energy technology, the electrochemical performance, the energy density and the stability of lithium batteries are required to be higher and higher, and the lithium iron manganese phosphate battery is used as a new generation lithium battery anode material, has higher working voltage, can greatly improve the energy density of the battery, has high safety, and has very wide application prospect in new energy industry.
However, research shows that the lithium iron manganese phosphate anode has two voltage platforms of manganese and iron in the charge and discharge process, so that DCR (direct current collector) bump points exist, impact can be caused on an electric appliance in the actual use process, and the practical application effect is limited. In the current application, the lithium iron manganese phosphate and the ternary material are mixed, and the battery is obtained according to the conventional process after pulping. This type of battery eliminates the double voltage plateau and DCR dump point in the BOL state, but after cycling for some time, the voltage double plateau and DCR dump point will reappear. Therefore, a lithium iron manganese phosphate battery capable of eliminating the problems of dual voltage platforms and DCR burst is to be studied.
Disclosure of Invention
The application provides a lithium ion battery and a preparation method thereof in order to avoid the problems of double voltage platforms and DCR burst of a lithium iron phosphate battery and improve the cycle performance of the lithium battery.
In a first aspect, the present application provides a lithium ion battery, which adopts the following technical scheme:
a lithium ion battery comprising a core pack including at least one first pole group and at least one second pole group therein; the first electrode group comprises a first positive electrode plate, wherein the active substance layer of the first positive electrode plate comprises a first positive electrode active material, and the first positive electrode active material comprises a lithium manganese iron phosphate material; the second electrode group comprises a second positive electrode plate, wherein the active substance layer of the second positive electrode plate comprises a second positive electrode active material, and the second positive electrode active material comprises any one of a ternary material and a lithium-rich manganese-based material;
wherein the surface density of the active material layer on the surface of the first positive electrode plate is 100-230g/m 2 The method comprises the steps of carrying out a first treatment on the surface of the The compaction density of the active material layer on the surface of the first positive electrode plate is 2.0-2.5g/cm 3 The method comprises the steps of carrying out a first treatment on the surface of the The surface density of the active material layer on the surface of the second positive electrode plate is 80-210g/m 2 The method comprises the steps of carrying out a first treatment on the surface of the Pressing the active material layer on the surface of the second positive electrode plateThe solid density is 3.2-3.6g/cm 3 The method comprises the steps of carrying out a first treatment on the surface of the The surface density of the active material layer on the surface of the first positive electrode sheet may be, for example, 100g/m 2 、130g/m 2 、180g/m 2 、200g/m 2 、230g/m 2 But are not limited to, the recited values, and other non-recited values within the range of values are equally applicable; the active material layer on the surface of the first positive electrode sheet may have a compacted density of 2g/m 3 、2.1g/m 3 、2.2g/m 3 、2.3g/m 3 、2.5g/m 3 But are not limited to, the recited values, and other non-recited values within the range of values are equally applicable; the surface density of the active material layer on the surface of the second positive electrode sheet may be 80g/m 2 、100g/m 2 、150g/m 2 、180g/m 2 、210g/m 2 But are not limited to, the recited values, and other non-recited values within the range of values are equally applicable; the active material layer on the surface of the second positive electrode sheet may have a compacted density of 3.2g/m 3 、3.3g/m 3 、3.5g/m 3 、3.6g/m 3 But are not limited to, the recited values, and other non-recited values within the range of values are equally applicable.
When the ternary material and the lithium iron manganese phosphate material are mixed for pulping and then coated on the surface of the foil to prepare the positive plate, although the problems of double voltage platforms and DCR burst of the lithium battery can be avoided in a BOL state (namely the battery is in the initial life), the problems of double voltage platforms and DCR burst of the lithium battery can still be found after the lithium battery is used for a period of time.
Preparing a first positive plate and a second positive plate respectively after independently pulping a ternary material and a lithium iron manganese phosphate material, and preparing a first pole group and a second pole group respectively by using the first positive plate and the second positive plate; firstly, as the voltage intervals of the ternary material and the lithium iron manganese phosphate material are similar, the ternary material and the lithium iron manganese phosphate material can be used in the same voltage interval by independently manufacturing the positive plate and the independent electrode group, and a double-voltage platform of a pure lithium iron manganese phosphate battery is eliminated after the charge and discharge curves of the ternary material and the lithium iron manganese phosphate material are mixed; secondly, the situation that lithium ions are excessively embedded in the lithium manganese iron phosphate in the positive plate coated with the mixed slurry due to the large gram capacity of the ternary material can be avoided, meanwhile, the influence of the difference of the microstructure changes of the ternary material and the lithium manganese iron phosphate in the use process can be avoided, and the cycling stability of the lithium manganese iron phosphate battery is improved; thirdly, by controlling the compaction density and the surface density of the first positive plate and the second positive plate, the phenomena that the structural change difference of the lithium iron manganese phosphate material and the ternary material is large and the performance attenuation is asynchronous in the use process of the lithium battery can be relieved, the stability of the first electrode group and the stability of the second electrode group and the coordination degree of the first electrode group and the second electrode group are improved, and the cycle life of the battery is prolonged; in addition, SEI films with proper thickness are generated on the surfaces of the first positive plate and the second positive plate in the initial formation stage of the battery, and the migration rate of lithium ions in the first pole group and the migration rate of lithium ions in the second pole group are regulated and controlled in the use process of the battery, so that the digestion rates of SEI films in the two pole groups are kept synchronous, and the coordination degree of the first pole group and the second pole group is further improved; the problem that the dual voltage platform and the DCR are suddenly increased after the lithium battery is used for a period of time is avoided.
In addition, the ternary material has higher requirement on environmental humidity control than the lithium iron manganese phosphate material, and compared with the process of mixing the ternary material and the lithium iron manganese phosphate material for pulping, the whole flow process needs to control the environmental humidity according to the requirement of the ternary material.
In summary, the first pole group and the second pole group are mutually matched, so that the conditions of dual voltage platform and DCR burst in the charging and discharging process of a pure manganese iron lithium phosphate battery in a BOL state can be avoided, the problem that the dual voltage platform and DCR burst are caused by the fact that the three-element material and manganese iron lithium phosphate have different microstructures and are mutually influenced due to the fact that the three-element material and manganese iron lithium phosphate have different microstructures and finally the cycle performance of the battery is poor is avoided, the cycle performance of the battery is improved, and the lithium battery still has excellent stability after being used for a period of time, and the problem that the dual voltage platform and the DCR burst are caused along with the increase of the cycle times is avoided; therefore, the matching of the first pole group and the second pole group can thoroughly solve the problems of double voltage platforms and DCR burst of the pure manganese iron lithium phosphate battery and improve the cycle performance of the lithium battery.
Preferably, the thickness of the active material layer on the surface of the first positive electrode sheet is 40-115 μm; for example, the values may be 40 μm, 50 μm, 55 μm, 60 μm, 70 μm, 80 μm, 90 μm, 110 μm, 115 μm, but the values are not limited to the values recited, and other values not recited in the numerical range are equally applicable.
Preferably, the thickness of the active material layer on the surface of the second positive electrode sheet is 22-66 μm; for example, the values may be 22 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 56 μm, 66 μm, but the values are not limited to the values recited, and other values not recited in the numerical range are equally applicable.
The thickness of the active material layer of the first positive plate and the thickness of the active material layer of the second positive plate are controlled, so that the migration rate of lithium ions in the circulating process of the first electrode group and the second electrode group is kept balanced, the differential effect of the first electrode group and the second electrode group under the effect of circulating diffusion induced stress in the circulating charge-discharge process is reduced, the attenuation speed of the first electrode group and the second electrode group which are mutually matched can be kept to a certain extent, and the problems of double voltage platforms and DCR sudden increases of the lithium battery in the long-term circulating process are avoided.
Preferably, the particle diameter D50 of the first positive electrode active material satisfies 0.5 μm.ltoreq.D50.ltoreq.1.3 μm; for example, the values may be 0.5 μm, 0.6 μm, 0.8 μm, 0.9 μm, 1 μm, 1.2 μm, 1.3 μm, but are not limited to the values recited, and other values not recited in the numerical range are equally applicable.
Preferably, the particle diameter D50 of the second positive electrode active material satisfies D50 of 3.2 μm or less and 4.2 μm or less; for example, the values may be 3.2 μm, 3.4 μm, 3.5 μm, 3.7 μm, 3.9 μm, 4 μm, 4.2 μm, but are not limited to the values recited, and other values not recited in the numerical range are equally applicable.
The pore diameter and pore diameter distribution of the electrode surface active material layer are more uniform by regulating and controlling the particle diameter D50 of the first positive electrode active material and the particle diameter D50 of the second positive electrode active material, and the lithium ion migration rate in the manganese iron lithium phosphate active material layer and the lithium ion migration rate in the ternary active material layer are controlled within a certain controllable range, so that the phenomenon that the deformation difference of the two positive electrode materials caused by cyclic charge and discharge is overlarge is avoided, and the problem that a double-voltage platform and DCR are suddenly increased in a long-term cyclic process of a lithium battery is avoided.
Preferably, the lithium iron manganese phosphate material used in the first positive electrode active material has a chemical formula of LiMn x Fe 1- x PO 4 X=0.4-0.68; for example, the values may be 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.68, but are not limited to the values recited, and other values not recited in the numerical range are equally applicable.
Preferably, the ternary material used in the second positive electrode active material has a chemical formula of Li (Ni y Co z Mn 1-y )O 2 Wherein y=0.5-0.95, z=0.05-0.45; for example, y may be 0.5, 0.55, 0.6, 0.75, 0.8, 0.95, and z may be 0.05, 0.1, 0.15, 0.25, 0.35, 0.45, but is not limited to the recited values, as other non-recited values within the range of values are equally applicable; the chemical formula of the lithium-rich manganese-based material used in the second positive electrode active material is aLi 2 MnO 3 ·(1-a)LiMO 2 Where 0 < a < 1, for example, may be 0.1, 0.2, 0.4, 0.6, 0.9, but is not limited to the values recited, and other non-recited values within the range of values are equally applicable; m comprises at least one of Ni, co and Mn.
Preferably, the first electrode group includes a first negative electrode sheet used in cooperation with the first positive electrode sheet, and the active material layer of the first negative electrode sheet includes a first negative electrode active material, where the first negative electrode active material is at least one of artificial graphite and natural graphite.
Preferably, the second electrode group includes a second negative electrode sheet used in cooperation with the second positive electrode sheet, and the active material layer of the second negative electrode sheet includes a second negative electrode active material, where the second negative electrode active material is at least one of silicon-containing graphite and hard carbon.
Different cathode materials are respectively matched with the first cathode plate and the second cathode plate, so that the lithium iron phosphate material, the ternary material and the lithium-rich manganese-based material can exert respective advantage performances to the greatest extent.
In a second aspect, the present application provides a method for preparing a lithium ion battery, which adopts the following technical scheme:
a preparation method of a lithium ion battery comprises the following steps:
step one, independently pulping the first positive electrode active material and the second positive electrode active material, and then respectively coating the first positive electrode active material and the second positive electrode active material on a foil to obtain a first positive electrode plate and a second positive electrode plate;
step two, assembling the first positive plate, the first negative plate and the diaphragm to obtain the first electrode group; assembling the second positive plate, the second negative plate and the diaphragm to obtain the second electrode group;
step three, assembling the first pole group and the second pole group to obtain a core package, and then assembling to obtain the lithium ion battery
Drawings
Fig. 1 is a graph of DCR data for a lithium ion battery of example 1.
Fig. 2 is a graph of DCR data for the lithium ion battery of comparative example 1.
Fig. 3 is a graph of DCR data for the lithium ion battery of comparative example 2.
Detailed Description
For a better understanding and implementation, the technical solutions of the present application will be clearly and completely described below in connection with examples.
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.
Unless otherwise indicated, all numbers expressing quantities of ingredients, reaction conditions, and so forth used in the specification and claims are to be understood as being modified in all instances by the term "about". Accordingly, unless indicated to the contrary, the numerical parameters set forth herein are approximations that may vary depending upon the desired properties to be obtained.
As used herein, "and/or" means one or all of the elements mentioned.
The use of "including" and "comprising" herein encompasses both the situation in which only the elements are mentioned and the situation in which other elements not mentioned are present in addition to the elements mentioned.
All percentages in the present application are by weight unless otherwise indicated.
As used in this specification, the terms "a," "an," "the," and "the" are intended to include "at least one" or "one or more," unless otherwise specified. For example, "a component" refers to one or more components, and thus more than one component may be considered and possibly employed or used in the practice of the embodiments.
Examples
Example 1
A lithium ion battery comprises a core pack, wherein the core pack is provided with a first pole group and a second pole group; the first electrode group comprises a first positive electrode plate, the active substance layer of the first positive electrode plate comprises a first positive electrode active material, the first positive electrode active material is d50=0.9 mu m of lithium manganese iron phosphate, and the chemical formula of the lithium manganese iron phosphate is LiMn 0.5 Fe 0.5 PO 4 The active material layer of the first positive electrode sheet had an areal density of 165g/m 2 A compacted density of 2.25g/cm 3 The thickness of the active material layer of the first positive electrode sheet was 73 μm; the second electrode group comprises a second positive electrode plate, the active substance layer of the second positive electrode plate comprises a second positive electrode active material, the second positive electrode active material is D50=3.7 mu m nickel cobalt lithium manganate, and the chemical formula of the nickel cobalt lithium manganate is Li (Ni 0.7 Co 0.25 Mn 0.3 )O 2 The active material layer of the second positive electrode sheet had an areal density of 145g/m 2 A compacted density of 3.4g/cm 3 The thickness of the active material layer of the second positive electrode sheet was 43 μm.
A preparation method of a lithium battery comprises the following steps:
the method comprises the steps of firstly, independently pulping a first positive electrode active material and a second positive electrode active material, and then respectively coating the first positive electrode active material and the second positive electrode active material on a foil to obtain a first positive electrode plate and a second positive electrode plate;
step two, assembling a first positive plate, a diaphragm and a first negative plate which uses artificial graphite as a first negative active material to obtain a first electrode group; assembling a second positive electrode sheet, a separator, and a second negative electrode sheet using a silica-containing ink as a second negative electrode active material to obtain a second electrode group;
and thirdly, assembling the first pole group and the second pole group to obtain a core package, and then assembling to obtain the lithium ion battery.
The DCR data graph of the lithium ion battery in this embodiment is shown in fig. 1.
Example 2
A lithium ion battery comprises a core pack, wherein the core pack is provided with a first pole group and a second pole group; the first electrode group comprises a first positive electrode plate, the active substance layer of the first positive electrode plate comprises a first positive electrode active material, the first positive electrode active material is d50=0.5 mu m lithium manganese iron phosphate, and the chemical formula of the lithium manganese iron phosphate is LiMn 0.68 Fe 0.32 PO 4 The active material layer of the first positive electrode sheet had an areal density of 100g/m 2 A compacted density of 2.5g/cm 3 The thickness of the active material layer of the first positive electrode sheet was 40 μm; the second electrode group comprises a second positive electrode plate, the active substance layer of the second positive electrode plate comprises a second positive electrode active material, the second positive electrode active material is D50=3.2 mu m nickel cobalt lithium manganate, and the chemical formula of the nickel cobalt lithium manganate is Li (Ni 0.5 Co 0.45 Mn 0.5 )O 2 The active material layer of the second positive electrode sheet had an areal density of 80g/m 2 A compacted density of 3.6g/cm 3 The thickness of the active material layer of the second positive electrode sheet was 22 μm.
A preparation method of a lithium battery comprises the following steps:
the method comprises the steps of firstly, independently pulping a first positive electrode active material and a second positive electrode active material, and then respectively coating the first positive electrode active material and the second positive electrode active material on a foil to obtain a first positive electrode plate and a second positive electrode plate;
step two, assembling a first positive plate, a diaphragm and a first negative plate using natural graphite as a first negative active material to obtain a first electrode group; assembling a second positive plate, a diaphragm and a second negative plate using hard carbon as a second negative active material to obtain a second electrode group;
and thirdly, assembling the first pole group and the second pole group to obtain a core package, and then assembling to obtain the lithium ion battery.
Example 3
A lithium ion battery comprises a core pack, wherein the core pack is provided with a first pole group and a second pole group; the first electrode group comprises a first positive electrode plate, the active substance layer of the first positive electrode plate comprises a first positive electrode active material, the first positive electrode active material is d50=1.3 mu m of lithium manganese iron phosphate, and the chemical formula of the lithium manganese iron phosphate is LiMn 0.4 Fe 0.6 PO 4 The active material layer of the first positive electrode sheet had an areal density of 230g/m 2 A compacted density of 2.0g/cm 3 The thickness of the active material layer of the first positive electrode sheet was 115 μm; the second electrode group comprises a second positive electrode plate, the active substance layer of the second positive electrode plate comprises a second positive electrode active material, the second positive electrode active material is D50=4.2 mu m nickel cobalt lithium manganate, and the chemical formula of the nickel cobalt lithium manganate is Li (Ni 0.95 Co 0.05 Mn 0.05 )O 2 The surface density of the active material layer of the second positive electrode sheet was 210g/m 2 A compacted density of 3.2g/cm 3 The thickness of the active material layer of the second positive electrode sheet was 66 μm.
A preparation method of a lithium battery comprises the following steps:
the method comprises the steps of firstly, independently pulping a first positive electrode active material and a second positive electrode active material, and then respectively coating the first positive electrode active material and the second positive electrode active material on a foil to obtain a first positive electrode plate and a second positive electrode plate;
step two, assembling a first positive plate, a diaphragm and a first negative plate using natural graphite as a first negative active material to obtain a first electrode group; assembling a second positive electrode sheet, a separator, and a second negative electrode sheet using a silica-containing ink as a second negative electrode active material to obtain a second electrode group;
and thirdly, assembling the first pole group and the second pole group to obtain a core package, and then assembling to obtain the lithium ion battery.
Example 4
The present embodiment is different from embodiment 1 in that the second pole groupComprises a second positive plate, wherein the active substance layer of the second positive plate comprises a second positive electrode active material, the second positive electrode active material is a lithium-rich manganese-based material with D50=4.2 mu m, and the chemical formula of the lithium-rich manganese-based material is 0.21Li 2 MnO 3 ·0.79LiNi 0.5 Mn 0.5 O 2 The method comprises the steps of carrying out a first treatment on the surface of the The remainder remained the same as in example 1.
Example 5
The present embodiment is different from embodiment 1 in that the particle size d50=0.2 μm of the first positive electrode active material, and the particle size d50=4.5 μm of the second positive electrode active material; the remainder remained the same as in example 1.
Example 6
The present embodiment is different from embodiment 1 in that the particle diameter d50=1.6 μm of the first positive electrode active material, and the particle diameter d50=2.9 μm of the second positive electrode active material; the remainder remained the same as in example 1.
Example 7
This example differs from example 1 in that the negative electrode active material of the first negative electrode sheet is a silica-containing ink; the remainder remained the same as in example 1.
Example 8
The present embodiment is different from embodiment 1 in that the negative electrode active material of the second negative electrode sheet is artificial graphite; the remainder remained the same as in example 1.
Comparative example 1
This comparative example differs from example 1 in that both pole sets in the core pack are the first pole set; the remainder remained the same as in example 1. The DCR data graph of the lithium ion battery in this comparative example is shown in fig. 2.
Comparative example 2
The difference between this comparative example and example 1 is that the core pack includes two identical mixed pole groups, the active material used in the active material layer of the positive plate of the mixed pole group is a mixture of nickel cobalt lithium manganate and manganese iron phosphate, and the mass ratio of nickel cobalt lithium manganate to manganese iron phosphate is 1:1, a step of; the remainder remained the same as in example 1. The DCR data graph of the lithium ion battery in this comparative example is shown in fig. 3.
Comparative example 3
The difference between this comparative example and example 1 is that the core pack includes two identical mixed pole groups, the active material used in the active material layer of the positive plate of the mixed pole group is a mixture of lithium-rich manganese-based material and manganese iron phosphate material, and the mass ratio of nickel cobalt lithium manganate to manganese iron phosphate is 1:1, a step of; the remainder was the same as in example 1.
Comparative example 4
This comparative example is different from example 1 in that the active material layer of the first positive electrode sheet has an areal density of 80g/m 2 A compacted density of 3.0g/cm 3 The method comprises the steps of carrying out a first treatment on the surface of the The remainder was the same as in example 1.
Comparative example 5
This comparative example is different from example 1 in that the active material layer of the first positive electrode sheet has an areal density of 250g/m 2 A compacted density of 1.5g/cm 3 The method comprises the steps of carrying out a first treatment on the surface of the The remainder was the same as in example 1.
Comparative example 6
This comparative example is different from example 1 in that the active material layer of the second positive electrode sheet has an areal density of 60g/m 2 A compacted density of 4.1g/cm 3 The method comprises the steps of carrying out a first treatment on the surface of the The remainder was the same as in example 1.
Comparative example 7
This comparative example is different from example 1 in that the active material layer of the second positive electrode sheet has an areal density of 230g/m 2 A compacted density of 2.7g/cm 3 The method comprises the steps of carrying out a first treatment on the surface of the The remainder was the same as in example 1.
Detection method
1. DCR test
The lithium batteries in examples 1 to 8 and comparative examples 1 to 7 were subjected to DCR test as follows: the following test operations were performed on the battery as a subject in an environment of 25 c: (1) standing for 5 minutes; (2) charging to 4.2V at constant current and constant voltage of 0.33C, and stopping current of 0.05C; (3) standing for 30 minutes; (4) constant-current discharging to the specified SOC at 0.33C; (5) rest for 60 minutes, record voltage as U 1 The method comprises the steps of carrying out a first treatment on the surface of the (6) Then I 1 Discharge for 30 seconds =1c, measured voltage U 2 The method comprises the steps of carrying out a first treatment on the surface of the Direct current internal resistance= (U) 1 -U 2 )/I 1 . Respectively testing the direct current internal resistance under 10% -90% of SOC, and representing whether a DCR bump point occurs or not by using the extreme difference value of the maximum value and the minimum value; and the polar differences are recorded in table 1.
2. Cycle performance test
The lithium batteries in examples 1 to 8 and comparative examples 1 to 7 were subjected to cycle performance test as follows: 1C/1C cycle test: the prepared battery was charged at a constant current and constant voltage of 1C rate and discharged at a constant current of 1C rate at 25C, and was subjected to a full charge discharge cycle test, which was repeated 1000 cycles, with recording capacity retention rates shown in table 1.
TABLE 1
Combining examples 1-4, comparative examples 1-7 and Table 1, it can be seen that after the lithium manganese iron phosphate and the ternary material are respectively and independently pulped, the lithium manganese iron phosphate and the ternary material are respectively coated on the foil to prepare a first positive plate and a second positive plate, the surface density and the compaction density of an active material layer on the surface of the first positive plate and the surface density and the compaction density of an active material layer on the surface of the second positive plate are controlled within a certain range, after the first positive plate and the second positive plate are respectively used to prepare a first electrode group and a second electrode group, DCR of the lithium battery is not increased suddenly after 100 weeks of cycle, and the cycle performance is best; the method is characterized in that firstly, when the ternary material and the lithium iron manganese phosphate material are pulped, a first positive plate and a second positive plate with good performance of the material can be obtained, the problem that DCR burst occurs in the recycled state of the lithium iron manganese phosphate battery is avoided, and meanwhile, the lithium iron manganese phosphate battery has good recycling performance; secondly, through the real density and the surface density of the first positive plate and the second positive plate, the phenomenon that the structural change difference of the lithium iron manganese phosphate material and the ternary material is large and asynchronous in the use process of the lithium battery can be relieved, the digestion rates of SEI films in two pole groups are kept synchronous, the coordination degree of the first pole group and the second pole group is further improved, the problem that a double-voltage platform and DCR are suddenly increased after the lithium battery is used for a period of time is avoided, and meanwhile, excellent cycle performance is also displayed.
In combination with examples 1, 5 to 6 and table 1, it can be seen that when the particle diameters D50 of the first positive electrode active material and the second positive electrode active material are too large or too small, both the conductivity and the cycle performance of the lithium battery are not good, because the above regulation and control can control the lithium ion migration rate to be controlled within a certain controllable range, the phenomenon that the deformation difference of the two positive electrode materials due to the cyclic charge and discharge is too large can be avoided, and the lithium battery can maintain long-term stability.
By combining embodiments 1, 7-8 and table 1, it can be seen that by arranging the first negative electrode plate and the second negative electrode plate respectively matched with the first positive electrode plate and the second positive electrode plate, the performance advantages of the first electrode group and the second electrode group can be fully exerted in the lithium battery, and further the comprehensive performance of the lithium battery is improved.
The present embodiment is only for explanation of the present application and is not to be construed as limiting the present application, and modifications to the present embodiment, which may not creatively contribute to the present application as required by those skilled in the art after reading the present specification, are all protected by patent laws within the scope of claims of the present application.
Claims (10)
1. A lithium ion battery, includes core package, its characterized in that: the core package comprises a first pole group and a second pole group; the first electrode group comprises a first positive electrode plate, wherein the active substance layer of the first positive electrode plate comprises a first positive electrode active material, and the first positive electrode active material comprises a lithium manganese iron phosphate material; the second electrode group comprises a second positive electrode plate, wherein the active substance layer of the second positive electrode plate comprises a second positive electrode active material, and the second positive electrode active material comprises any one of a ternary material and a lithium-rich manganese-based material;
wherein the surface density of the active material layer on the surface of the first positive electrode plate is 100-230g/m 2 The method comprises the steps of carrying out a first treatment on the surface of the The compaction density of the active material layer on the surface of the first positive electrode plate is 2.0-2.5g/cm 3 The method comprises the steps of carrying out a first treatment on the surface of the The surface density of the active material layer on the surface of the second positive electrode plate is 80-210g/m 2 The method comprises the steps of carrying out a first treatment on the surface of the The compaction density of the active material layer on the surface of the second positive electrode plate is 3.2-3.6g/cm 3 。
2. A lithium ion battery according to claim 1, wherein: the thickness of the active material layer on the surface of the first positive electrode sheet is 40-115 mu m.
3. A lithium ion battery according to claim 1, wherein: the thickness of the active material layer on the surface of the second positive plate is 22-66 mu m.
4. A lithium ion battery according to claim 1, wherein: the particle diameter D50 of the first positive electrode active material satisfies D50 of 0.5 μm or less and 1.3 μm or less.
5. A lithium ion battery according to claim 1, wherein: the particle diameter D50 of the second positive electrode active material satisfies D50 of 3.2 μm or less and 4.2 μm or less.
6. A lithium ion battery according to claim 1, wherein: the chemical formula of the lithium iron manganese phosphate material used in the first positive electrode active material is LiMn x Fe 1-x PO 4 ，x＝0.4-0.68。
7. A lithium ion battery according to claim 1, wherein: the ternary material used in the second positive electrode active material has a chemical formula of Li (Ni y Co z Mn 1-y )O 2 Wherein y=0.5-0.95, z=0.05-0.45; the chemical formula of the lithium-rich manganese-based material used in the second positive electrode active material is aLi 2 MnO 3 ·(1-a)LiMO 2 Wherein 0 < a < 1, and M comprises at least one of Ni, co and Mn.
8. A lithium ion battery according to claim 1, wherein: the first electrode group comprises a first negative electrode plate matched with the first positive electrode plate, the active material layer of the first negative electrode plate comprises a first negative electrode active material, and the first negative electrode active material is at least one of artificial graphite and natural graphite.
9. A lithium ion battery according to claim 8, wherein: the second electrode group comprises a second negative electrode plate matched with the second positive electrode plate, the active material layer of the second negative electrode plate comprises a second negative electrode active material, and the second negative electrode active material is at least one of silicon-containing graphite and hard carbon.
10. A method for preparing a lithium ion battery according to any one of claims 1 to 9, characterized in that: the method comprises the following steps:
step one, independently pulping the first positive electrode active material and the second positive electrode active material, and then respectively coating the first positive electrode active material and the second positive electrode active material on a foil to obtain a first positive electrode plate and a second positive electrode plate;
step two, assembling the first positive plate, the first negative plate and the diaphragm to obtain the first electrode group; assembling the second positive plate, the second negative plate and the diaphragm to obtain the second electrode group;
and thirdly, assembling the first pole group and the second pole group to obtain a core package, and then assembling to obtain the lithium ion battery.
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