CN114976032B - Composite pole piece, electrochemical device and electronic equipment - Google Patents
Composite pole piece, electrochemical device and electronic equipment Download PDFInfo
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- CN114976032B CN114976032B CN202210453009.2A CN202210453009A CN114976032B CN 114976032 B CN114976032 B CN 114976032B CN 202210453009 A CN202210453009 A CN 202210453009A CN 114976032 B CN114976032 B CN 114976032B
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- pole piece
- current collector
- composite pole
- thickness direction
- active material
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- 239000002131 composite material Substances 0.000 title claims abstract description 145
- 239000011148 porous material Substances 0.000 claims abstract description 7
- 239000011149 active material Substances 0.000 claims description 78
- 238000000926 separation method Methods 0.000 claims description 4
- 239000003792 electrolyte Substances 0.000 abstract description 50
- 230000005540 biological transmission Effects 0.000 abstract description 26
- 230000006866 deterioration Effects 0.000 abstract description 12
- 238000013461 design Methods 0.000 abstract description 11
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 abstract description 9
- 229910001416 lithium ion Inorganic materials 0.000 abstract description 9
- 150000001875 compounds Chemical class 0.000 abstract description 5
- 230000006872 improvement Effects 0.000 description 7
- 238000003475 lamination Methods 0.000 description 6
- 238000006243 chemical reaction Methods 0.000 description 4
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 3
- 238000000576 coating method Methods 0.000 description 3
- 238000009792 diffusion process Methods 0.000 description 3
- 239000007788 liquid Substances 0.000 description 3
- 229910052744 lithium Inorganic materials 0.000 description 3
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 2
- 229910052782 aluminium Inorganic materials 0.000 description 2
- 239000011248 coating agent Substances 0.000 description 2
- 238000005056 compaction Methods 0.000 description 2
- 239000006260 foam Substances 0.000 description 2
- 230000008595 infiltration Effects 0.000 description 2
- 238000001764 infiltration Methods 0.000 description 2
- 150000002500 ions Chemical class 0.000 description 2
- 239000007791 liquid phase Substances 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 239000007790 solid phase Substances 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 235000015842 Hesperis Nutrition 0.000 description 1
- 235000012633 Iberis amara Nutrition 0.000 description 1
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- HMDDXIMCDZRSNE-UHFFFAOYSA-N [C].[Si] Chemical compound [C].[Si] HMDDXIMCDZRSNE-UHFFFAOYSA-N 0.000 description 1
- KFDQGLPGKXUTMZ-UHFFFAOYSA-N [Mn].[Co].[Ni] Chemical compound [Mn].[Co].[Ni] KFDQGLPGKXUTMZ-UHFFFAOYSA-N 0.000 description 1
- 239000000853 adhesive Substances 0.000 description 1
- 230000001070 adhesive effect Effects 0.000 description 1
- 230000001668 ameliorated effect Effects 0.000 description 1
- 238000005452 bending Methods 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 239000006258 conductive agent Substances 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 239000011889 copper foil Substances 0.000 description 1
- 239000011162 core material Substances 0.000 description 1
- 238000009831 deintercalation Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 229910003460 diamond Inorganic materials 0.000 description 1
- 239000010432 diamond Substances 0.000 description 1
- QHGJSLXSVXVKHZ-UHFFFAOYSA-N dilithium;dioxido(dioxo)manganese Chemical compound [Li+].[Li+].[O-][Mn]([O-])(=O)=O QHGJSLXSVXVKHZ-UHFFFAOYSA-N 0.000 description 1
- 239000002270 dispersing agent Substances 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000011888 foil Substances 0.000 description 1
- 229910002804 graphite Inorganic materials 0.000 description 1
- 239000010439 graphite Substances 0.000 description 1
- 229910021385 hard carbon Inorganic materials 0.000 description 1
- 230000037427 ion transport Effects 0.000 description 1
- DCYOBGZUOMKFPA-UHFFFAOYSA-N iron(2+);iron(3+);octadecacyanide Chemical compound [Fe+2].[Fe+2].[Fe+2].[Fe+3].[Fe+3].[Fe+3].[Fe+3].N#[C-].N#[C-].N#[C-].N#[C-].N#[C-].N#[C-].N#[C-].N#[C-].N#[C-].N#[C-].N#[C-].N#[C-].N#[C-].N#[C-].N#[C-].N#[C-].N#[C-].N#[C-] DCYOBGZUOMKFPA-UHFFFAOYSA-N 0.000 description 1
- 230000001788 irregular Effects 0.000 description 1
- GELKBWJHTRAYNV-UHFFFAOYSA-K lithium iron phosphate Chemical compound [Li+].[Fe+2].[O-]P([O-])([O-])=O GELKBWJHTRAYNV-UHFFFAOYSA-K 0.000 description 1
- 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 description 1
- 229910052748 manganese Inorganic materials 0.000 description 1
- 239000011572 manganese Substances 0.000 description 1
- 238000004519 manufacturing process Methods 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
- 229920000447 polyanionic polymer Polymers 0.000 description 1
- 229960003351 prussian blue Drugs 0.000 description 1
- 239000013225 prussian blue Substances 0.000 description 1
- 238000005096 rolling process Methods 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 239000002002 slurry Substances 0.000 description 1
- 229910021384 soft carbon Inorganic materials 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 239000000758 substrate Substances 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
- 230000032258 transport Effects 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
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/64—Carriers or collectors
- H01M4/66—Selection of materials
- H01M4/665—Composites
- H01M4/667—Composites in the form of layers, e.g. coatings
-
- 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
- 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
-
- 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
- H01M4/64—Carriers or collectors
- H01M4/70—Carriers or collectors characterised by shape or form
- H01M4/80—Porous plates, e.g. sintered carriers
-
- 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
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Materials Engineering (AREA)
- Composite Materials (AREA)
- Manufacturing & Machinery (AREA)
- Cell Electrode Carriers And Collectors (AREA)
- Battery Electrode And Active Subsutance (AREA)
Abstract
The application relates to a compound pole piece, electrochemical device and electronic equipment, compound pole piece include the electric current collector, along the thickness direction of electric current collector, at least three electric current collector range upon range of setting, and first pore structure has been seted up to the electric current collector, from compound pole piece thickness direction's center to compound pole piece thickness direction's both ends face, the porosity of electric current collector increases gradually. The first hole structure can be completely infiltrated and filled by electrolyte to become a new lithium ion transmission channel, the porosities of the current collectors at the two end surfaces are larger, more electrolyte can be transmitted to the current collector at the center of the composite pole piece, the porosities of the current collector at the center are smaller, the strength of the current collector at the center is ensured, the dynamic deterioration of the pole piece can be effectively relieved through the gradient design of the porosities of the current collector, and the transmission efficiency of the electrolyte is improved.
Description
[ field of technology ]
The embodiment of the application relates to the technical field of batteries, in particular to a composite pole piece, an electrochemical device and electronic equipment.
[ background Art ]
With the popularization of electric automobiles, electric bicycles and some portable electric devices, the energy density requirements of batteries are also increasing. Currently, an effective way to increase the energy density of a battery is to increase the active material content of the pole piece, i.e., to increase the thickness of the pole piece. However, in practical application, when the thickness of the pole piece is increased to a certain value, the transmission channel of ions is blocked easily, so that the electric performance of the battery is deteriorated. Therefore, how to improve the ion transmission rate on the premise of increasing the thickness of the pole piece as much as possible has become an important problem of the application prospect of the battery.
[ invention ]
The embodiment of the application aims to provide a composite pole piece, an electrochemical device and electronic equipment, so that at least the efficiency of electrolyte can be improved.
In order to solve the technical problems, the embodiment of the application adopts the following technical scheme:
in a first aspect, embodiments of the present application provide a composite pole piece, including a current collector, and at least three current collectors are stacked along a thickness direction of the current collector. And a first hole structure is formed in the current collector along the thickness direction of the current collector, and the porosity of the current collector is gradually increased from the center of the thickness direction of the composite pole piece to the two end surfaces of the thickness direction of the composite pole piece.
Through the lamination arrangement of at least three current collectors, the overall strength of the composite pole piece can be improved. The first hole structure can be completely infiltrated and filled by electrolyte to become a new lithium ion transmission channel, the porosities of the current collectors at the two end surfaces are larger, more electrolyte can be transmitted to the current collector at the center of the composite pole piece, the porosities of the current collector at the center are smaller, the strength of the current collector at the center is ensured, the dynamic deterioration of the composite pole piece can be effectively relieved through the gradient design of the porosities of the current collector, and the transmission efficiency of the electrolyte is improved.
As a further improvement scheme of the technical scheme, along the thickness direction of the composite pole piece, the porosity of the current collector positioned at the center of the composite pole piece is 3% -10%, and the porosity of the current collectors positioned at the two end faces of the composite pole piece is 10% -30%.
The 3% -30% of porosity can improve the transmission efficiency of the electrolyte while guaranteeing the strength of the current collectors, the porosity of each current collector can be specifically determined according to the number of the current collectors in the composite pole piece, and when the number of the current collectors is large, the porosity of the current collectors at the two end faces can be properly increased.
As a further improvement of the above technical solution, on the surface of the current collector, the area of the single first hole structure is 0.4-4 square millimeters; and/or, the distance between two adjacent first hole structures is 2-20 micrometers on the surface of the current collector.
The area of the first hole structure of each current collector can also be designed in a gradient way, the current collectors on the two end faces in the thickness direction can be first hole structures with larger areas, the current collectors on the center in the thickness direction can be first hole structures with smaller areas, and the electrolyte is conveniently transmitted to the center of the composite pole piece from the two end faces of the composite pole piece through the area gradient design of the first hole structures, so that the transmission rate of the electrolyte is improved.
As a further improvement of the above technical solution, the composite pole piece further includes a plurality of active material layers, and the active material layers are coated on at least one surface of each current collector. And the active material layers are provided with second hole structures along the thickness direction of the current collector, and the porosities of the active material layers are gradually increased from the center of the thickness direction of the composite pole piece to the two end surfaces of the thickness direction of the composite pole piece.
Each current collector is coated with an active material layer such that the mass ratio of the active material layer in the battery is greater to improve the energy density of the battery. The second pore structure can be fully infiltrated and filled by the electrolyte to become a liquid phase transmission channel of lithium ions, so that the reaction area of a solid-liquid interface is effectively increased, and the diffusion coefficient of the electrolyte in the active material layer is increased, so that the active material layer is quickly infiltrated. The active material layers on the two end surfaces and the current collectors on the two end surfaces have larger porosity, so that more electrolyte can be quickly transmitted to the center of the composite pole piece, the dynamic deterioration of the composite pole piece is relieved, and the transmission efficiency of the electrolyte is improved.
As a further improvement of the above technical solution, the compaction density of the plurality of active material layers gradually increases from the center of the composite pole piece to both end faces of the composite pole piece in the thickness direction of the composite pole piece.
By controlling the compacted density of each active material layer, a gradient design of the porosity of the active material layer is formed, the active material layers on the two end surfaces have larger porosity, and the compacted density of the part can be increased when the active material layers are coated, so that the energy density of the battery is improved.
As a further improvement scheme of the technical scheme, the porosity of each active material layer is 5% -40%, so that the transmission of electrolyte in the thickness direction of the composite pole piece is improved; and/or at least part of the second hole structure is communicated with the first hole structure, so that the electrolyte can easily pass through the two through holes to enter the center of the composite pole piece in the thickness direction, and the transmission rate of the electrolyte can be effectively improved.
As a further improvement of the above technical solution, the thickness of the current collector is 2 to 20 micrometers along the thickness direction of the current collector. The current collector with the thickness of the micron order is also smaller in thickness after being stacked for a plurality of times, so that the influence on the energy density of the battery is reduced.
According to some embodiments of the present application, in a second aspect, the present application further proposes an electrochemical device, including an isolating film and the composite pole piece according to any one of the above embodiments, the composite pole piece is divided into a positive composite pole piece and a negative composite pole piece, the isolating film is disposed between the positive composite pole piece and the negative composite pole piece, and the positive composite pole piece, the isolating film and the negative composite pole piece are sequentially laminated or wound.
As a further improvement of the above technical scheme, along the thickness direction of the positive composite pole piece, the two end faces of the positive composite pole piece are both provided with the isolating film, and in the positive composite pole piece, the porosity of the current collector close to the isolating film is greater than that of the current collector far away from the isolating film. And in the negative electrode composite pole piece, the porosity of a current collector close to the isolating film is larger than that of a current collector far away from the isolating film. Through the gradient design of the current collector, the electrolyte is conveniently transmitted to the center of the composite pole piece, so that the dynamic deterioration of the pole piece is relieved, and the transmission of the electrolyte is improved.
According to some embodiments of the present application, in a third aspect, the present application further proposes an electronic device comprising an electrochemical apparatus according to any one of the embodiments described above.
The foregoing description is only an overview of the technical solutions of the present application, and may be implemented according to the content of the specification in order to make the technical means of the present application more clearly understood, and in order to make the above-mentioned and other objects, features and advantages of the present application more clearly understood, the following detailed description of the present application will be given.
[ description of the drawings ]
One or more embodiments are illustrated by way of example and not limitation in the figures of the accompanying drawings, in which like references indicate similar elements, and in which the figures of the drawings are not to scale, unless expressly stated otherwise.
FIG. 1 is a schematic illustration of a lamination of a composite pole piece according to some embodiments of the present application;
FIG. 2 is a schematic illustration of the lamination of a composite pole piece according to some embodiments of the present application;
FIG. 3 is a schematic structural view of a current collector according to some embodiments of the present application;
FIG. 4 is a schematic diagram illustrating lithium ion transport according to some embodiments of the present application;
FIG. 5 is a schematic illustration of the application of an active material layer to a current collector according to some embodiments of the present application;
FIG. 6 is a schematic illustration of the lamination of a composite pole piece according to some embodiments of the present application;
FIG. 7 is a schematic illustration of the application of an active material layer to a current collector according to some embodiments of the present application;
fig. 8 is a schematic structural view of an electrochemical device according to some embodiments of the present application;
fig. 9 is a schematic illustration of lamination of a composite pole piece inside an electrochemical device according to some embodiments of the present application.
In the figure:
10. a composite pole piece;
11. a current collector; 11a, a first current collector; 11b, a second current collector; 11c, a third current collector; 11d, a fourth current collector; 11e, fifth current collector; 111. a long side; 112. a broadside; 113. a thickness edge; 114. a major surface; 115. a first aperture structure;
12. an active material layer; 121. a second aperture structure;
110. a negative electrode composite pole piece; 120. a positive electrode composite pole piece;
200. a separation film;
1000. an electrochemical device.
[ detailed description ] of the invention
In order to facilitate an understanding of the present application, the present application will be described in more detail below with reference to the accompanying drawings and specific examples. It will be understood that when an element is referred to as being "disposed" or "connected" to another element, it can be directly connected to the other element or one or more intervening elements may be present therebetween. The terms "vertical," "upper," "lower," "left," "right," "inner," "outer," and the like are used in this specification for purposes of illustration only.
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 in the description of the present application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.
In the description of the embodiments of the present application, the term "and/or" is merely an association relationship describing an association object, which means that three relationships may exist, for example, a and/or B may mean: a exists alone, A and B exist together, and B exists alone. In addition, the character "/" herein generally indicates that the front and rear associated objects are an "or" relationship.
In the description of embodiments of the present application, the terms "first," "second," and the like are used merely to distinguish between different objects and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated, a particular order or a primary or secondary relationship. In the description of the embodiments of the present application, the meaning of "plurality" is two or more unless explicitly defined otherwise.
In addition, the technical features described below in the different embodiments of the present application may be combined with each other as long as they do not collide with each other. Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the present application. The appearances of such phrases in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments.
Currently, in order to improve the problem of pole piece dynamics deterioration, when an active material layer is coated, a multi-coating mode is generally adopted so as to realize different compaction densities and conductivities of each active material layer, thereby improving the problem of pole piece dynamics to a certain extent. However, multiple coating processes and different active material slurries can increase the manufacturing cost of the pole piece and have high design difficulty.
In order to alleviate the deterioration of pole piece dynamics and improve the transmission of electrolyte, in a first aspect, an embodiment of the present application proposes a composite pole piece 10, please refer to fig. 1 and 2, where the composite pole piece 10 includes current collectors 11, and at least three current collectors 11 are stacked along the thickness direction of the current collectors 11.
For the current collector 11, the current collector 11 is a conductive substrate of the composite pole piece 10, the composite pole piece 10 may be divided into a positive composite pole piece 120 and a negative composite pole piece 110, different materials may be selected as the current collector 11 of the composite pole piece 10 according to different polarities, for example, the positive composite pole piece 120 may use aluminum foil or foam aluminum as the current collector 11, and the negative composite pole piece 110 may use copper foil or foam copper. Referring to fig. 3, fig. 3 shows a structure in which the current collector 11 is spread out in a flat state. The current collector 11 has a flat strip-like structure as a whole, and the thickness of each part is basically uniform, and is usually between 2 micrometers and 20 micrometers. Current collector 11 has long side 111, wide side 112, and thick side 113; the long side 111 is a side extending in the longitudinal direction (X direction) of the current collector 11 when the current collector 11 is in a flat state, the wide side 112 is a side extending in the width direction (Y direction) of the current collector 11 when the current collector 11 is in a flat state, and the thick side 113 is a side extending in the thickness direction (Z direction) of the current collector 11 when the current collector 11 is in a flat state. Current collector 11 has two major surfaces 114, the major surfaces 114 being defined by the long side 111 and the wide side 112, the two major surfaces 114 being disposed opposite each other along the thickness side 113.
Referring to fig. 3 and 4, along the thickness direction of the current collector 11, a first hole structure 115 is formed on the current collector 11, the first hole structure 115 can be completely infiltrated and filled with electrolyte to form a new lithium ion transmission channel, and the first hole structure 115 can penetrate through the current collector 11, so that the electrolytes on both sides of the current collector 11 in the thickness direction are mutually communicated.
For the active material layer 12, the active material layer 12 is a core material layer of the composite pole piece 10, referring to fig. 5, the active material layer 12 is coated on the main surface 114 of the current collector 11, and in this embodiment, both main surfaces 114 are coated with the active material layer 12; of course, in other embodiments, only one major surface 114 may be coated with the active material layer 12. The active material layer 12 generally includes an active material, a conductive agent, a dispersing agent, an adhesive, and the like, and the active material layer 12 is obtained by mixing the above materials, stirring the mixture uniformly, and coating the mixture on the main surface 114 of the above current collector 11. It should be noted that the specific components of the active material layer 12 are very diverse, for example, for the positive electrode composite pole piece 120, the active material may be, for example: lithium cobaltate, lithium-rich manganese base, lithium iron phosphate, lithium manganese iron phosphate, nickel cobalt manganese ternary, lithium manganate, polyanion compound, prussian blue and the like; for the negative electrode composite sheet 110, the active material thereof may be selected from, for example: hard carbon, soft carbon, graphite, silicon carbon silica, lithium titanate, and the like.
In order to increase the thickness of the electrode sheet and increase the energy density of the battery, in this embodiment, referring to fig. 2, at least three current collectors 11 are stacked along the thickness direction of the current collectors 11 to form a composite electrode sheet 10, and two main surfaces 114 of each current collector 11 are coated with an active material layer 12, so that the mass ratio of the active material layer 12 in the battery is larger to increase the energy density of the battery. Through the lamination arrangement of at least three current collectors 11, the overall strength of the composite pole piece 10 can be improved, the active material layer 12 can serve as a solid phase transmission channel of lithium ions, electrolyte can directly infiltrate the active material layer 12, so that part of electrolyte can penetrate out of the first hole structures 115 of the current collectors 11, the electrolyte can infiltrate from the two ends of the composite pole piece 10 in the thickness direction to the center, and the active material layer 12 of each current collector 11 can be infiltrated by the electrolyte.
In order to further improve the transmission efficiency of the electrolyte, in this embodiment, the porosity of the current collector 11 gradually increases from the center of the thickness direction of the composite pole piece 10 to the two end faces of the thickness direction of the composite pole piece 10 along the thickness direction of the composite pole piece 10 (i.e., the porosity of the current collector 11 at the two end faces is greater than that of the center current collector 11). The current collectors 11 at the two end surfaces have larger porosity, so that more electrolyte can be transmitted to the current collector 11 at the center of the composite pole piece 10, and the transmission efficiency of the electrolyte is improved. The central current collector 11 does not generally need to pass through the electrolyte, so the central current collector 11 can be set to have a smaller porosity to secure the strength of the central current collector 11. By means of gradient design of the porosity of the current collector 11, dynamic deterioration of the pole piece can be effectively relieved, and the transmission efficiency of the electrolyte is improved.
In this embodiment, at least three current collectors 11 are stacked along the thickness direction thereof to form a composite pole piece 10, and the thickness direction of the composite pole piece 10 is the thickness direction of the current collector 11; in addition, according to the difference of the number of the current collectors 11, the center of the composite pole piece 10 in the thickness direction will also be different, and when the number of the current collectors 11 is singular (the number of the current collectors 11 is at least 3), only one current collector 11 exists in the lamination center, and the current collector 11 is the center of the composite pole piece 10 in the thickness direction; when the number of the current collectors 11 is a double number (the number of the current collectors 11 is at least 3), there are two current collectors 11 at the lamination center, and the center in the thickness direction of the composite pole piece 10 is located between the two current collectors 11, and the two current collectors 11 may be referred to as a central current collector 11.
As for the porosity of the current collector 11, in one embodiment, the porosity of the current collector 11 located at the center of the composite pole piece 10 is 3% to 10% and the porosity of the current collectors 11 located at both end surfaces of the composite pole piece 10 is 10% to 30% in the thickness direction of the composite pole piece 10. In this embodiment, taking five current collectors 11 as an example, please refer to fig. 2, the five current collectors 11 are stacked in sequence, and the five current collectors 11 are respectively: a first current collector 11a, a second current collector 11b, a third current collector 11c, a fourth current collector 11d, and a fifth current collector 11e. The current collector 11 positioned at the center of the composite pole piece 10 in the thickness direction is the third current collector 11c, the porosity of the third current collector 11c may be set to 3% to 10%, the porosities of the second current collector 11b and the fourth current collector 11d may be set to be the same, both are 6% to 20%, and the porosities of the first current collector 11a and the fifth current collector 11e at both end surfaces may be set to 10% to 30%. When the number of the current collectors 11 of the composite pole piece 10 is two, specifically, referring to fig. 6, the composite pole piece 10 includes four current collectors 11, the current collectors 11 at the center of the composite pole piece 10 are the second current collector 11b and the third current collector 11c, the porosities of the second current collector 11b and the third current collector 11c can be set to 3% to 10%, and the porosities of the first current collector 11a and the fourth current collector 11d at the two end surfaces can be set to 10% to 30%. It should be noted that, the porosity of each current collector 11 may be specifically determined according to the number of current collectors 11 in the composite pole piece 10, and when the number of current collectors 11 is large, the porosity of the current collectors 11 at the two end surfaces may be appropriately increased. In this embodiment, in order to realize a gradient design of the porosity of the current collector 11 from the center in the thickness direction to any one of the end faces in the thickness direction of the composite pole piece 10, the composite pole piece 10 includes at least three current collectors 11.
In order to facilitate the electrolyte to fully infiltrate the active material layer 12, in one embodiment, referring to fig. 7, the active material layer 12 is provided with a second hole structure 121 along the thickness direction of the composite pole piece 10. The second hole structure 121 can be completely infiltrated and filled by the electrolyte to become a liquid phase transmission channel of lithium ions, so that the reaction area of a solid-liquid interface is effectively increased, and the diffusion coefficient of the electrolyte in the active material layer 12 is increased, so that the active material layer 12 is quickly infiltrated. The second hole structure 121 can make lithium ions more easily intercalate into the active material layer 12, and reduce the difficulty of deintercalating lithium ions in the active material layer 12, thereby improving the overall kinetics of the composite pole piece 10. The second hole structure 121 may be a blind hole or a through hole, and when a through hole is used, at least a portion of the second hole structure 121 is in communication with the first hole structure 115, so that the electrolyte can easily pass through the two through holes to enter the center of the composite pole piece 10 in the thickness direction, thereby effectively improving the transmission rate of the electrolyte.
As for the porosity of the active material layers 12 described above, the porosity of each active material layer 12 may be set to 5% to 40%. In one embodiment, to facilitate rapid infiltration of the entire composite pole piece 10 with electrolyte, the porosity of the plurality of active material layers 12 increases gradually from the center in the thickness direction of the composite pole piece 10 to the two end faces in the thickness direction of the composite pole piece 10. For example, when the composite pole piece 10 includes five current collectors 11, referring to fig. 2, the active material layer 12 on the central third current collector 11c may be set to have a porosity of 5% to 15%; while the active material layer 12 of the second current collector 11b and the active material layer 12 of the fourth current collector 11d may each be set to 15% to 25% in porosity; the active material layer 12 of the first current collector 11a and the active material layer 12 of the fifth current collector 11e of both end surfaces may have a porosity of 25% to 40%. Alternatively, when the number of the composite pole pieces 10 is two, referring to fig. 6, the porosity of each of the active material layers 12 of the second current collector 11b and the active material layers 12 of the third current collector 11c in the center may be set to 5% to 20%; the active material layer 12 of the first current collector 11a and the active material layer 12 of the fourth current collector 11d of both end surfaces may have a porosity of 20% to 40%. It should be noted that the porosity gradient of the active material layer 12 may be specifically determined according to the number of current collectors 11, and when the number of current collectors 11 is large, the gradient may be correspondingly reduced, and conversely, the gradient may be increased. In this embodiment, the active material layers 12 on the two end surfaces and the current collectors 11 on the two end surfaces have larger porosity, so that more electrolyte can be quickly transferred to the center of the composite pole piece 10, so as to alleviate dynamic deterioration of the composite pole piece 10 and improve the transfer efficiency of the electrolyte.
The porosity gradient of each current collector 11 can be achieved by rolling each active material layer 12 to a different compacted density. The greater the compacted density of the active material layer 12, the greater the energy density, but the slower the solid phase transport rate of the electrolyte. In the present application, this problem can be ameliorated by increasing the porosity, and the larger the porosity, the larger the contact area between the active material layer 12 and the electrolyte can be made, so that the electrolyte infiltration efficiency can be improved. Thus, in one embodiment, the compacted density of the plurality of active material layers 12 gradually increases from the center of the composite pole piece 10 to both end faces of the composite pole piece 10 in the thickness direction of the current collector 11. Since the active material layer 12 of both end surfaces has a large porosity, the compacted density of the portion can be increased to increase the energy density when the active material layer 12 is coated.
For the above-described first hole structures 115, the shape of the first hole structures 115 may be a circle, a diamond, a triangle, a square, an ellipse, an irregular polygon, or the like, and the area of the individual first hole structures 115 may be set to 0.4 square millimeters to 4 square millimeters on the surface of the current collector 11. The area of the first hole structures 115 of each current collector 11 may also be designed in a gradient, for example, the area of the first hole structures 115 of the current collectors 11 at both end surfaces may be set to 3 to 4 square millimeters, and the area of the first hole structures 115 of the current collectors 11 at the center may be set to 0.4 to 4 square millimeters. The area gradient of the first hole structures 115 may be set according to circumstances, which is not limited. Based on the same inventive concept, the active material layer 12 of each current collector 11 may also be provided with an area gradient of the second pore structure 121 accordingly.
Each current collector 11 is provided with a plurality of first hole structures 115, in one embodiment, referring to fig. 7, the plurality of first hole structures 115 are distributed on the current collector 11 in an array, and two adjacent first hole structures 115 are disposed at intervals, wherein the distance between two adjacent first hole structures 115 (the shortest distance between boundaries) may be set to 2 micrometers to 20 micrometers. The hole spacing of the current collectors 11 of the two end surfaces may be set smaller to ensure a larger porosity, and the hole spacing of the current collector 11 of the center may be set larger. The hole pitch may be set according to the specific case, and is not limited herein. Likewise, the plurality of second pore structures 121 may also be distributed in an array over the active material layer 12.
In the embodiment of the application, through the plurality of current collectors 11 which are stacked, each current collector 11 is coated with the active material layer 12, so that the mass ratio of the active material layer 12 in the battery is larger, and the energy density of the battery is improved. The current collector 11 is provided with the first hole structure 115, and the porosity of the current collector 11 is gradually increased from the center of the composite pole piece 10 to the two end faces of the composite pole piece 10 along the thickness direction of the composite pole piece 10, so that the dynamic deterioration of the pole piece can be effectively relieved through the gradient design of the porosity of the current collector 11, and the transmission efficiency of electrolyte is improved. Meanwhile, the second hole structure 121 is formed on the active material layer 12, so that the reaction area of a solid-liquid interface is effectively increased, the diffusion coefficient of the electrolyte in the active material layer 12 is increased, the active material layer 12 is quickly infiltrated, and more electrolyte can be quickly transmitted to the center of the composite pole piece 10 due to the gradient design of the porosity of the active material layer 12, so that the dynamic deterioration of the composite pole piece 10 is relieved, and the transmission efficiency of the electrolyte is improved.
Based on the same inventive concept, an electrochemical device 1000 is further provided in the embodiments of the present application, referring to fig. 8 and 9, the electrochemical device 1000 includes a separator 200 and the composite electrode sheet 10 described in any of the embodiments above, the composite electrode sheet 10 is divided into a positive composite electrode sheet 120 and a negative composite electrode sheet 110, the separator 200 is disposed between the positive composite electrode sheet 120 and the negative composite electrode sheet 110 to separate the positive composite electrode sheet 120 and the negative composite electrode sheet 110, and the positive composite electrode sheet 120, the separator 200 and the negative composite electrode sheet 110 are sequentially stacked and wound. In the embodiment of the present application, the electrochemical device 1000 is a minimum unit constituting a battery or a battery module, and is a site for specifically implementing electric energy and chemical energy conversion.
Various small holes with bending curves are formed on the isolating film 200 for electrolyte transmission, in one embodiment, the isolating film 200 is disposed on two end surfaces of the positive electrode composite pole piece 120 along the thickness direction of the positive electrode composite pole piece 120, and in the positive electrode composite pole piece 120, the porosity of the current collector 11 near the isolating film 200 is greater than that of the current collector 11 far from the isolating film 200. The gradient design of the current collector 11 is adopted to facilitate the electrolyte to be transmitted to the center of the composite pole piece 10, thereby relieving the dynamic deterioration of the composite pole piece and improving the transmission of the electrolyte. Based on the same inventive concept, in the thickness direction of the negative electrode composite sheet 110, both end surfaces of the negative electrode composite sheet 110 are provided with separator films 200, and in the negative electrode composite sheet 110, the porosity of the current collector 11 near the separator films 200 is greater than the porosity of the current collector 11 far from the separator films 200.
According to some embodiments of the present application, in a third aspect, the present application also proposes an electronic device comprising an electrochemical apparatus 1000 according to any one of the embodiments described above.
The electrochemical device 1000 disclosed in the embodiments of the present application may be used in, but not limited to, electronic equipment such as vehicles, ships, or aircraft. The power supply system having the electrochemical device 1000 and the like disclosed in the present application constituting the electronic apparatus can be used, which is advantageous in alleviating deterioration of pole piece dynamics and improving transmission of electrolyte.
The embodiment of the present application provides an electronic device using an electrochemical device 1000 or a battery module as a power source, which may be, but is not limited to, a mobile phone, a tablet, a notebook computer, an electric toy, an electric tool, a battery car, an electric automobile, a ship, a spacecraft, and the like. Among them, the electric toy may include fixed or mobile electric toys, such as game machines, electric car toys, electric ship toys, electric plane toys, and the like, and the spacecraft may include planes, rockets, space planes, and spacecraft, and the like.
Finally, it should be noted that the above embodiments are merely for illustrating the technical solution of the present application, and are not limiting thereof; the technical features of the above embodiments or in the different embodiments may also be combined under the idea of the present application, the steps may be implemented in any order, and there are many other variations of the different aspects of the present application as described above, which are not provided in details for the sake of brevity; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.
Claims (9)
1. The composite pole piece comprises a current collector, at least three current collectors are stacked along the thickness direction of the current collector, and is characterized in that,
along the thickness direction of the current collectors, each current collector is provided with a first hole structure, and the porosity of each current collector is sequentially increased from the center of the thickness direction of the composite pole piece to the two end surfaces of the thickness direction of the composite pole piece;
the composite pole piece further comprises a plurality of active material layers, wherein the active material layers are coated on at least one surface of each current collector to form a plurality of independent pole pieces;
and along the thickness direction of the current collector, each active material layer is provided with a second hole structure, and the porosity of each active material layer is gradually increased from the center of the thickness direction of the composite pole piece to the two end surfaces of the thickness direction of the composite pole piece.
2. The composite pole piece of claim 1, wherein the porosity of the current collector located at the center of the composite pole piece is 3% -10% and the porosity of the current collectors located at both end surfaces of the composite pole piece is 10% -30% along the thickness direction of the composite pole piece.
3. The composite pole piece of claim 1 or 2, wherein the area of the individual first pore structure on the surface of the current collector is 0.4-4 square millimeters; and/or the number of the groups of groups,
and the distance between two adjacent first hole structures is 2-20 microns on the surface of the current collector.
4. The composite pole piece of claim 1, wherein the compacted density of the plurality of active material layers increases gradually from the center of the composite pole piece to both end faces of the composite pole piece in the thickness direction of the composite pole piece.
5. The composite pole piece of claim 1 or 4, wherein the porosity of each active material layer is 5% to 40%; and/or the number of the groups of groups,
at least a portion of the second pore structure communicates with the first pore structure.
6. The composite pole piece of any of claims 1-5, wherein the current collector has a thickness of 2-20 microns along the thickness of the current collector.
7. An electrochemical device, characterized by comprising a separation film and the composite pole piece according to any one of claims 1-6, wherein the composite pole piece is divided into a positive composite pole piece and a negative composite pole piece, the separation film is arranged between the positive composite pole piece and the negative composite pole piece, and the positive composite pole piece, the separation film and the negative composite pole piece are sequentially laminated or wound.
8. The electrochemical device according to claim 7, wherein,
the separator is arranged on two end faces of the positive composite pole piece along the thickness direction of the positive composite pole piece, and in the positive composite pole piece, the porosity of a current collector close to the separator is larger than that of a current collector far from the separator;
and in the negative electrode composite pole piece, the porosity of a current collector close to the isolating film is larger than that of a current collector far away from the isolating film.
9. An electronic device comprising the electrochemical device according to claim 7 or 8.
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