CN214672685U - Pole piece and lithium ion battery - Google Patents
Pole piece and lithium ion battery Download PDFInfo
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- CN214672685U CN214672685U CN202023314065.3U CN202023314065U CN214672685U CN 214672685 U CN214672685 U CN 214672685U CN 202023314065 U CN202023314065 U CN 202023314065U CN 214672685 U CN214672685 U CN 214672685U
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- active layer
- pole piece
- groove
- current collector
- thickness
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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
- 238000005087 graphitization Methods 0.000 claims description 10
- 239000002245 particle Substances 0.000 claims description 10
- 239000011149 active material Substances 0.000 claims description 8
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 13
- 230000000052 comparative effect Effects 0.000 description 13
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical group [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 9
- 239000011889 copper foil Substances 0.000 description 9
- 239000000463 material Substances 0.000 description 9
- 229910002804 graphite Inorganic materials 0.000 description 8
- 239000010439 graphite Substances 0.000 description 8
- 238000002360 preparation method Methods 0.000 description 7
- 230000014759 maintenance of location Effects 0.000 description 6
- 239000002002 slurry Substances 0.000 description 6
- 239000002033 PVDF binder Substances 0.000 description 5
- 238000000576 coating method Methods 0.000 description 5
- 229920002981 polyvinylidene fluoride Polymers 0.000 description 5
- 238000012360 testing method Methods 0.000 description 5
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 4
- 239000011248 coating agent Substances 0.000 description 4
- 229910052744 lithium Inorganic materials 0.000 description 4
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 3
- 229910052782 aluminium Inorganic materials 0.000 description 3
- 230000007423 decrease Effects 0.000 description 3
- 239000011888 foil Substances 0.000 description 3
- 238000011056 performance test Methods 0.000 description 3
- 239000011345 viscous material Substances 0.000 description 3
- 239000013543 active substance Substances 0.000 description 2
- 239000000853 adhesive Substances 0.000 description 2
- 230000001070 adhesive effect Effects 0.000 description 2
- 230000008901 benefit Effects 0.000 description 2
- 239000011230 binding agent Substances 0.000 description 2
- 239000006258 conductive agent Substances 0.000 description 2
- 239000003792 electrolyte Substances 0.000 description 2
- 229920000058 polyacrylate Polymers 0.000 description 2
- -1 polytetrafluoroethylene Polymers 0.000 description 2
- 238000011160 research Methods 0.000 description 2
- 239000002562 thickening agent Substances 0.000 description 2
- BQCIDUSAKPWEOX-UHFFFAOYSA-N 1,1-Difluoroethene Chemical compound FC(F)=C BQCIDUSAKPWEOX-UHFFFAOYSA-N 0.000 description 1
- AFCARXCZXQIEQB-UHFFFAOYSA-N N-[3-oxo-3-(2,4,6,7-tetrahydrotriazolo[4,5-c]pyridin-5-yl)propyl]-2-[[3-(trifluoromethoxy)phenyl]methylamino]pyrimidine-5-carboxamide Chemical compound O=C(CCNC(=O)C=1C=NC(=NC=1)NCC1=CC(=CC=C1)OC(F)(F)F)N1CC2=C(CC1)NN=N2 AFCARXCZXQIEQB-UHFFFAOYSA-N 0.000 description 1
- 229910019142 PO4 Inorganic materials 0.000 description 1
- 239000004952 Polyamide Substances 0.000 description 1
- 229920002125 Sokalan® Polymers 0.000 description 1
- PFYQFCKUASLJLL-UHFFFAOYSA-N [Co].[Ni].[Li] Chemical compound [Co].[Ni].[Li] PFYQFCKUASLJLL-UHFFFAOYSA-N 0.000 description 1
- YWJVFBOUPMWANA-UHFFFAOYSA-H [Li+].[V+5].[O-]P([O-])([O-])=O.[O-]P([O-])([O-])=O Chemical compound [Li+].[V+5].[O-]P([O-])([O-])=O.[O-]P([O-])([O-])=O YWJVFBOUPMWANA-UHFFFAOYSA-H 0.000 description 1
- KLARSDUHONHPRF-UHFFFAOYSA-N [Li].[Mn] Chemical compound [Li].[Mn] KLARSDUHONHPRF-UHFFFAOYSA-N 0.000 description 1
- XKGIZIQMMABGJQ-UHFFFAOYSA-N [Mn](=O)(=O)([O-])[O-].[Mn+2].[Co+2].[Ni+2].[Li+] Chemical compound [Mn](=O)(=O)([O-])[O-].[Mn+2].[Co+2].[Ni+2].[Li+] XKGIZIQMMABGJQ-UHFFFAOYSA-N 0.000 description 1
- DPXJVFZANSGRMM-UHFFFAOYSA-N acetic acid;2,3,4,5,6-pentahydroxyhexanal;sodium Chemical compound [Na].CC(O)=O.OCC(O)C(O)C(O)C(O)C=O DPXJVFZANSGRMM-UHFFFAOYSA-N 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 239000010405 anode material Substances 0.000 description 1
- 229910021383 artificial graphite Inorganic materials 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 239000002041 carbon nanotube Substances 0.000 description 1
- 229910021393 carbon nanotube Inorganic materials 0.000 description 1
- 239000001768 carboxy methyl cellulose Substances 0.000 description 1
- 239000010406 cathode material Substances 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 229920001577 copolymer Polymers 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
- 229910021389 graphene Inorganic materials 0.000 description 1
- 230000005484 gravity Effects 0.000 description 1
- HCDGVLDPFQMKDK-UHFFFAOYSA-N hexafluoropropylene Chemical group FC(F)=C(F)C(F)(F)F HCDGVLDPFQMKDK-UHFFFAOYSA-N 0.000 description 1
- 238000005304 joining Methods 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
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- 229910021382 natural graphite Inorganic materials 0.000 description 1
- 239000007773 negative electrode material Substances 0.000 description 1
- 239000010452 phosphate Substances 0.000 description 1
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 description 1
- 229920003229 poly(methyl methacrylate) Polymers 0.000 description 1
- 239000004584 polyacrylic acid Substances 0.000 description 1
- 229920002239 polyacrylonitrile Polymers 0.000 description 1
- 229920002647 polyamide Polymers 0.000 description 1
- 239000004926 polymethyl methacrylate Substances 0.000 description 1
- 229920001343 polytetrafluoroethylene Polymers 0.000 description 1
- 239000004810 polytetrafluoroethylene Substances 0.000 description 1
- 229920001289 polyvinyl ether Polymers 0.000 description 1
- 229920000036 polyvinylpyrrolidone Polymers 0.000 description 1
- 239000001267 polyvinylpyrrolidone Substances 0.000 description 1
- 235000013855 polyvinylpyrrolidone Nutrition 0.000 description 1
- 239000007774 positive electrode material Substances 0.000 description 1
- 238000005096 rolling process Methods 0.000 description 1
- 235000019812 sodium carboxymethyl cellulose Nutrition 0.000 description 1
- 229920001027 sodium carboxymethylcellulose Polymers 0.000 description 1
- 229920003048 styrene butadiene rubber Polymers 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 description 1
- 229910052721 tungsten Inorganic materials 0.000 description 1
- 239000010937 tungsten Substances 0.000 description 1
- 125000005287 vanadyl group Chemical group 0.000 description 1
Images
Classifications
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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
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- Secondary Cells (AREA)
- Battery Electrode And Active Subsutance (AREA)
Abstract
The utility model provides a pole piece and lithium ion battery. The utility model provides a pole piece, the pole piece includes the current collector, the first active layer, the second active layer, the first active layer sets up in the surface of current collector to be provided with the first recess, the second active layer divide into set up in the first recess the first part and set up in the first active layer keep away from the second part on the surface of current collector; the first part is provided with a second groove, a tab is arranged at the second groove and electrically connected with the current collector, and the thickness of the first part of the second active layer is smaller than the total thickness of the second parts of the first active layer and the second active layer. The utility model provides a pole piece through the thickness that reduces near utmost point ear active layer, has improved utmost point ear hookup location's the risk of charging to a certain extent, has improved lithium ion battery's cyclicity ability.
Description
Technical Field
The utility model relates to a pole piece and lithium ion battery relates to lithium ion battery technical field.
Background
With the advent of the 5G era, the status of lithium ion batteries has become increasingly important. At present, the lithium ion battery is continuously developed towards the direction of high energy density and high rapid charging rate. At present, the impedance of the lithium ion battery is reduced by adjusting the connection position of the tab from the edge of the pole piece to the middle position of the side surface of the pole piece.
However, when the position of the tab is changed, the current density around the tab is increased, and lithium ions are precipitated as the lithium ion battery is cycled, resulting in poor cycle performance of the lithium ion battery. Therefore, more and more attention is paid to how to solve the problem that the cycle performance of the lithium ion battery is deteriorated due to the tab connection mode.
SUMMERY OF THE UTILITY MODEL
The utility model provides a pole piece for solve the problem that the lithium ion battery cycle performance that leads to because this kind of utmost point ear connected mode worsens.
The utility model provides a pole piece, the pole piece includes the current collector, the first active layer, the second active layer, the first active layer sets up in the surface of current collector to be provided with the first recess, the second active layer divide into set up in the first recess the first part and set up in the first active layer keep away from the second part on the surface of current collector;
the first part is provided with a second groove, a tab is arranged at the second groove and electrically connected with the current collector, and the thickness of the first part of the second active layer is smaller than the total thickness of the second parts of the first active layer and the second active layer.
Currently, the pole piece used in the prior art generally includes a current collector and an active layer disposed on the surface of the current collector, and a groove is disposed in the middle of the side of the active layer, the groove is connected with a tab in a corresponding region on the current collector, in order to solve the problem of poor cycle performance of the lithium ion battery caused by the tab connection mode, the present invention reduces the thickness of the active layer around the tab, specifically, fig. 1a is a front view of the pole piece provided by an embodiment of the present invention, fig. 1b is a top view of the pole piece provided by an embodiment of the present invention, fig. 1c is a left view of the pole piece provided by an embodiment of the present invention, as shown in fig. 1a-1c, the pole piece includes a current collector 1, a first active layer 2, a second active layer 3 and a tab 4, wherein the first active layer 2 is disposed on the surface of the current collector 1, and a first groove is disposed on the first active layer 2, a first part of the second active layer is arranged in the first groove and is in contact with the surface of the current collector 1, a second part of the second active layer is arranged on the upper surface, away from the current collector 1, of the first active layer 1, a second groove is formed in the middle of the side surface of the first part of the second active layer and is used for connecting a tab 4, and the thickness of the first part of the second active layer is smaller than the total thickness of the first active layer and the second part of the second active layer, so that the thickness of the active layer close to the periphery of the tab is smaller than that of the active layer far away from the tab area; the definition of the thickness of the pole piece is the same as that of the prior art, namely, the longest side in the pole piece is the length of the pole piece, the shortest side is the height of the pole piece, the sides between the longest side and the shortest side are the width of the pole piece, namely, the longer side is the length of the pole piece and the shorter side is the height of the pole piece in fig. 1a, the shorter side is the width of the pole piece in fig. 1b, the value of the long side is the length of the pole piece, the value of the high side is the thickness of the pole piece, the value of the wide side is the width of the pole piece, and the first groove and the second groove are the same as the length, the width and the thickness direction of the pole piece. The utility model provides a pole piece through the gross thickness that reduces active layer around utmost point ear, has improved utmost point ear hookup location's the risk of charging to a certain extent, has improved lithium ion battery's cyclicity ability.
In one embodiment, in order to further improve the cycle performance of the lithium ion battery, the thickness of the first active layer should be appropriately reduced, i.e., the thickness of the second active layer is greater than the thickness of the first active layer. In addition, because the first part of the second active layer is arranged in the first groove, the stress is small in the subsequent pole piece rolling process, so that the thickness difference of the first part and the second part of the second active layer occurs, and particularly, the thickness of the first part of the second active layer is larger than that of the second part.
According to the pole piece structure shown in fig. 1a-1c, the existing coating equipment needs to be improved to ensure the position and the area of the first groove, so that the preparation cost is increased, and the preparation of other pole piece structures is not facilitated. For example:
fig. 2a is the front view of the pole piece provided by another embodiment of the present invention, fig. 2b is the top view of the pole piece provided by another embodiment of the present invention, as shown in fig. 2a-2b, the pole piece includes a current collector 1, a first active layer 2, a second active layer 3 and a tab 4, the first active layer 1 is provided with a first groove, and the width of the first groove is the same as the width of the current collector 1, that is, the first groove divides the first active layer 2 into two parts, the first part of the second active layer 3 is disposed in the first groove, and the second part of the second active layer 3 is disposed on the upper surface of the current collector 1 away from the first active layer 2, because the width of the first groove is the same as the width of the current collector, the second part of the second active layer 3 is also divided into two independent parts.
It can be understood that the center of the vertical projection of the second groove on the current collector is located in the first groove, with the intersection point of the diagonals of the vertical projection area of the second groove on the current collector as the center.
As can be seen by continuing to refer to fig. 1b or 2b, the center of the vertical projection of the second groove on the current collector is located in the first groove, and in order to further improve the cycle performance of the lithium ion battery, the second groove may be disposed in the center of the first groove as much as possible, so that the thicknesses of the active layers on both sides of the tab are the same.
The applicant researches and discovers that the area of the cross section of the first groove and the second groove in the length direction has a larger influence on the performance of the lithium ion battery, and specifically, the vertical projection area of the second groove on the current collector is 1% -50% of the vertical projection area of the first groove on the current collector. In a specific preparation process, the width of the first groove and the width of the second groove can be determined by a person skilled in the art, and the area ratio of the first groove and the second groove can be adjusted by adjusting the length range of the first groove and the second groove.
In order to improve the quick charge performance of the lithium ion battery, when the pole piece is a negative pole piece, the average particle size of the active substance in the second active layer is 5-20 μm, and the graphitization degree is 90% -98%.
The utility model provides a pole piece is applicable to the positive plate equally, and when the pole piece was the positive plate, the material of first active layer used high viscous substance generally in order to improve lithium ion battery's security performance, but because the viscosity of this material is great, when rinsing first recess place region in to first active layer, the unable rinse-out thoroughly of high viscous substance, make first recess correspond regional internal existence high viscous substance and remain, influence utmost point ear and the being connected of mass flow body, lead to utmost point ear unable intermediate position of connecting in the mass flow side. Therefore, use the utility model provides a pole piece structure can effectively avoid this problem, and first active layer uses high-viscosity material promptly to follow-up only need wash the second active layer, need not to wash first active layer, specifically, high-viscosity material is the adhesive that includes molecular weight 800000 + 2000000 in the active layer material, and the quality of adhesive is 3% -40% of first active layer total mass.
In addition, the thickness of first active layer and second active layer is great to lithium ion battery performance influence in the pole piece, through the utility model discloses people's research discovery in the application, when the thickness proportion increase of first active layer, lithium ion battery's cycle performance can moderate degree decline, consequently, the thickness of first active layer is first active layer with 5% -80% of the gross thickness of the second part of second active layer.
When the pole piece is a positive pole piece, the thickness of the first active layer should be reduced appropriately, for example, fig. 3 is a front view of the positive pole piece provided in an embodiment of the present invention, as shown in fig. 3, when the pole piece is a positive pole piece, the thickness of the first portion of the second active layer should be higher than the thickness of the first active layer.
On the basis of the pole piece structure provided by the utility model, the technicians in the field can combine the existing pole piece preparation method to carry out, specifically, first active layer slurry and second active layer slurry are prepared; secondly, coating the prepared first active layer slurry on the surface of a current collector, performing blank coating in an area corresponding to a first groove to obtain a first active layer provided with the first groove, then coating a second active layer slurry according to a conventional pole piece coating process, wherein part of the second active layer slurry fills the first groove under the action of gravity to obtain a first part of a second active layer, the rest of the second active layer slurry obtains a second part of the second active layer, finally, cleaning the active layer in the middle area of the first part in the first groove to obtain a second groove, and arranging a pole lug in the second groove to be electrically connected with the current collector to obtain the pole piece.
The skilled person can select the materials of the positive plate and the negative plate in combination with the prior art, for example, when the plate is a positive plate, the current collector can be an aluminum foil, and the positive active material includes at least one of lithium cobaltate, lithium manganate, lithium nickelate, lithium nickel cobalt manganese manganate, lithium iron phosphate, lithium manganese iron phosphate, lithium vanadium phosphate, lithium vanadyl phosphate, lithium manganese rich-based material, and lithium nickel cobalt aluminate;
when the pole piece is a negative pole piece, the current collector can be copper foil, and the negative active substance comprises at least one of artificial graphite, natural graphite and modified graphite;
the binder and the conductive agent used for the positive electrode sheet and the negative electrode sheet are the same, and specifically, the binder may include at least one of polyvinylidene fluoride (PVDF), a copolymer of vinylidene fluoride and hexafluoropropylene, polyamide, polyacrylonitrile, polyacrylate, polyacrylic acid, polyacrylate, polyvinylpyrrolidone, polyvinyl ether, polymethyl methacrylate, polytetrafluoroethylene, polyhexafluoropropylene, and Styrene Butadiene Rubber (SBR); the conductive agent may include at least one of conductive carbon black, carbon nanotubes, conductive graphite, graphene; the negative plate can also comprise a thickening agent, and the thickening agent can be sodium carboxymethyl cellulose.
It can be understood that the second grooves are used for connecting the tabs, and therefore, the width of the second grooves is smaller than that of the first grooves along the width direction of the current collector.
In the actual preparation process, in order to facilitate the connection of the tab and the current collector, the vertical projection area of the second groove on the current collector can be enlarged, so that the vertical projection area of the second groove on the current collector is larger than the area of the tab connection area on the current collector.
Fig. 4 is the utility model discloses a plan view of utmost point ear that still another embodiment provided, as shown in fig. 4, length, the width of first recess all are greater than the area of utmost point ear joining region on the mass flow body to utmost point ear 4 and the being connected of mass flow body 1.
Further, the width of the second groove is 1-2 times of the width of the tab connection area, and the length of the second groove is 1-2 times of the length of the tab connection area.
To sum up, the utility model provides a pole piece through the thickness that reduces near utmost point ear active layer, has improved utmost point ear hookup location's the risk of charging to a certain extent, has improved lithium ion battery's cyclicity ability.
The utility model discloses the second aspect provides a lithium ion battery, including any one of the above-mentioned pole pieces.
The utility model provides a pole piece, the technical personnel in the field are in the utility model provides a on the basis of pole piece, combine the prior art preparation to obtain lithium ion battery. The utility model provides a lithium ion battery possesses better cycle performance.
The utility model discloses an implement, have following advantage at least:
1. the utility model provides a pole piece through the thickness that reduces near utmost point ear active layer, has improved utmost point ear hookup location's the risk of charging to a certain extent, has improved lithium ion battery's cyclicity ability.
2. The utility model provides a pole piece is all applicable to positive plate or negative pole piece.
3. When the pole piece is the positive plate, the utility model provides a pole piece structure can avoid leading to unable problem at the central current collector side with utmost point ear connection owing to the existence of the high viscidity material in first active layer.
4. The utility model provides a lithium ion battery has better cycle performance.
Drawings
Fig. 1a is a front view of a pole piece according to an embodiment of the present invention;
fig. 1b is a top view of a pole piece according to an embodiment of the present invention;
fig. 1c is a left side view of a pole piece according to an embodiment of the present invention;
fig. 2a is a front view of a pole piece according to another embodiment of the present invention;
fig. 2b is a top view of a pole piece according to another embodiment of the present invention;
fig. 3 is a front view of a pole piece according to another embodiment of the present invention;
fig. 4 is a top view of a pole piece according to another embodiment of the present invention.
Description of reference numerals:
1: a current collector;
2: a first active layer;
3: a second active layer;
4: and (7) a tab.
Detailed Description
To make the objects, technical solutions and advantages of the present invention clearer, embodiments of the present invention are combined to clearly and completely describe the technical solutions in the embodiments of the present invention, and obviously, the described embodiments are some embodiments of the present invention, not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative work belong to the protection scope of the present invention.
Example 1
The pole piece provided by this embodiment is a positive pole piece, and a front view, a top view and a left view of the structure thereof are shown in fig. 3, 4 and 1c, respectively, wherein:
the current collector is an aluminum foil, and the width of the current collector is 79 mm;
the width of the first groove is 79mm, and the length of the first groove is 15 mm;
the width of the second groove is 25mm, and the length of the second groove is 10 mm;
the thickness of the first active layer is 10 μm, and the thickness of the second active layer is 80 μm;
the material used for the first active layer is a high-viscosity substance and comprises lithium cobaltate, conductive carbon and polyvinylidene fluoride, wherein the molecular weight of the polyvinylidene fluoride is 800000, and the mass of the polyvinylidene fluoride is 20% of the total mass of the first active layer.
Example 2
The pole piece provided in this embodiment is a negative pole piece, and a front view of the structure thereof is shown in fig. 2a, a top view thereof is shown in fig. 4, and a left view thereof is shown in fig. 1c, where:
the current collector is copper foil, and the width of the current collector is 81 mm;
the width of the first groove is 81mm, and the length of the first groove is 50 mm;
the width of the second groove is 25mm, and the length of the second groove is 10 mm;
the thickness of the first active layer is 50 μm, and the thickness of the second active layer is 50 μm;
the active material used in the second active layer was graphite, the average particle diameter of which was 15 μm, and the degree of graphitization was 94%.
Example 3
The pole piece provided in this embodiment is a negative pole piece, and a front view of the structure thereof is shown in fig. 3, a top view thereof is shown in fig. 4, and a left view thereof is shown in fig. 1c, where:
the current collector is copper foil, and the width of the current collector is 81 mm;
the width of the first groove is 81mm, and the length of the first groove is 50 mm;
the width of the second groove is 25mm, and the length of the second groove is 10 mm;
the thickness of the first active layer is 30 μm, and the thickness of the second active layer is 70 μm;
the active material used in the second active layer was graphite, the average particle diameter of which was 15 μm, and the degree of graphitization was 94%.
Example 4
The pole piece provided in this embodiment is a negative pole piece, and a front view of the structure thereof is shown in fig. 3, a top view thereof is shown in fig. 4, and a left view thereof is shown in fig. 1c, where:
the current collector is copper foil, and the width of the current collector is 81 mm;
the width of the first groove is 81mm, and the length of the first groove is 50 mm;
the width of the second groove is 25mm, and the length of the second groove is 10 mm;
the thickness of the first active layer is 40 μm, and the thickness of the second active layer is 60 μm;
the active material used in the second active layer was graphite, the average particle diameter of which was 15 μm, and the degree of graphitization was 94%.
Example 5
The pole piece provided in this embodiment is a negative pole piece, and a front view of the structure thereof is shown in fig. 2a, a top view thereof is shown in fig. 4, and a left view thereof is shown in fig. 1c, where:
the current collector is copper foil, and the width of the current collector is 81 mm;
the width of the first groove is 81mm, and the length of the first groove is 50 mm;
the width of the second groove is 25mm, and the length of the second groove is 10 mm;
the thickness of the first active layer is 50 μm, and the thickness of the second active layer is 50 μm;
the active material used in the second active layer was graphite, the average particle diameter of which was 10 μm, and the degree of graphitization was 92%.
Example 6
The pole piece provided in this embodiment is a negative pole piece, and a front view of the structure thereof is shown in fig. 2a, a top view thereof is shown in fig. 4, and a left view thereof is shown in fig. 1c, where:
the current collector is copper foil, and the width of the current collector is 81 mm;
the width of the first groove is 81mm, and the length of the first groove is 50 mm;
the width of the second groove is 25mm, and the length of the second groove is 10 mm;
the thickness of the first active layer is 50 μm, and the thickness of the second active layer is 50 μm;
the active material used in the second active layer was graphite, the average particle diameter of which was 10 μm, and the degree of graphitization was 95%.
Example 7
The pole piece provided in this embodiment is a negative pole piece, and a front view of the structure thereof is shown in fig. 2a, a top view thereof is shown in fig. 4, and a left view thereof is shown in fig. 1c, where:
the current collector is copper foil, and the width of the current collector is 81 mm;
the width of the first groove is 81mm, and the length of the first groove is 50 mm;
the width of the second groove is 25mm, and the length of the second groove is 10 mm;
the thickness of the first active layer is 50 μm, and the thickness of the second active layer is 50 μm;
the active material used in the second active layer was graphite, the average particle diameter of which was 15 μm, and the degree of graphitization was 92%.
Example 8
The pole piece provided in this embodiment is a negative pole piece, and a front view of the structure thereof is shown in fig. 2a, a top view thereof is shown in fig. 4, and a left view thereof is shown in fig. 1c, where:
the current collector is copper foil, and the width of the current collector is 81 mm;
the width of the first groove is 81mm, and the length of the first groove is 50 mm;
the width of the second groove is 25mm, and the length of the second groove is 10 mm;
the thickness of the first active layer is 50 μm, and the thickness of the second active layer is 50 μm;
the active material used in the second active layer was graphite, the average particle diameter of which was 15 μm, and the degree of graphitization was 95%.
Comparative example 1
The pole piece that this comparative example provided is positive plate, including the mass flow body and the active layer of setting on the mass flow body surface, utmost point ear is connected in mass flow body edgemost one side, wherein:
the current collector is an aluminum foil, and the width of the current collector is 79 mm;
the thickness of the active layer was 90 μm.
Comparative example 2
The pole piece that this comparative example provided is the negative pole piece, including the mass flow body and set up first active layer and the second active layer on the mass flow body surface, be provided with the recess in the middle of first active layer and the second active layer side, utmost point ear is connected in this recess, wherein:
the current collector is copper foil, and the width of the current collector is 81 mm;
the width of the groove is 25mm, and the length of the groove is 10 mm;
the total thickness of the first active layer and the second active layer was 100 μm.
The utility model discloses on the basis of the pole piece that embodiment 1-8 and comparative example 1-2 provided, the lithium ion battery is obtained in the preparation of the same negative pole piece/positive plate of collocation structure, diaphragm and electrolyte, for example, embodiment 1 and comparative example 1 are the positive plate, then the structure of corresponding negative pole piece is the same with the positive plate structure, embodiment 2-8 and comparative example 2 are the negative pole piece, then the structure of corresponding positive plate is the same with the negative pole piece structure to cycle performance to lithium ion battery tests.
The cathode material is purchased from Xiamen tungsten new energy materials Co., Ltd, the anode material is purchased from Shanghai fir technology Co., Ltd, the diaphragm is purchased from Dongguan Shanghai electronics technology Co., Ltd, and the electrolyte is purchased from Shenzhen New Zhou Banaban technology Co., Ltd.
The performance test method of the lithium ion battery comprises the following steps:
carrying out 2C/0.7C charge-discharge cycle test on the lithium ion batteries prepared on the basis of the embodiment 1 and the comparative example 1 at 25 ℃, and calculating the cycle retention rate (%); and monitoring the surface temperature of the battery cell by using a temperature sensor, recording the difference value of the maximum value and the initial temperature as the temperature rise (DEG C) of the lithium ion battery, and showing the test result in table 1.
The lithium ion batteries prepared on the basis of examples 2-8 and comparative example 2 were subjected to 2C/0.7C charge-discharge cycle test at 25 deg.C/10 deg.C, and the cycle retention (%) was calculated, respectively, and the test results are shown in Table 2.
Table 1 results of performance tests of lithium ion batteries provided in example 1 and comparative example 1
| Cycle retention at 25 deg.C | Temperature rise on the surface of the battery cell | |
| Example 1 | 84.80％ | 13℃ |
| Comparative example 1 | 83.90％ | 16℃ |
Table 2 examples 2-8 and comparative example 2 provide cycle performance test results for lithium ion batteries
| Cycle retention at 25 deg.C | Cycle retention at 10 ℃ of | |
| Example 2 | 85.10％ | 83.00％ |
| Example 3 | 86.10％ | 84.00％ |
| Example 4 | 85.50％ | 83.00％ |
| Example 5 | 86.00％ | 84.50％ |
| Example 6 | 84.90％ | 83.30％ |
| Example 7 | 85.30％ | 83.50％ |
| Example 8 | 83.00％ | 82.60％ |
| Comparative example 2 | 82.00％ | 81.00％ |
As can be seen from tables 1-2, the lithium ion batteries provided in examples 1-8 all had better cycle performance; according to the data provided in examples 2-4, the performance of the lithium ion battery decreases moderately as the proportion of the first active layer to the total thickness of the active layers increases, and therefore, the thickness of the first active layer should be controlled; according to the data provided in examples 5 to 8, in the negative electrode sheet, the cycle retention rate of the lithium ion battery decreases as the average particle diameter and graphitization degree of the negative electrode active material in the second active layer increase.
Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; although the present invention has been described in detail with reference to the foregoing embodiments, it should be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; such modifications and substitutions do not depart from the spirit and scope of the present invention.
Claims (9)
1. A pole piece is characterized by comprising a current collector, a first active layer and a second active layer, wherein the first active layer is arranged on the surface of the current collector and is provided with a first groove, and the second active layer is divided into a first part arranged in the first groove and a second part arranged on the first active layer and far away from the surface of the current collector;
the first part is provided with a second groove, a tab is arranged at the second groove and electrically connected with the current collector, and the thickness of the first part of the second active layer is smaller than the total thickness of the second parts of the first active layer and the second active layer.
2. The pole piece of claim 1, wherein the thickness of the second active layer is greater than the thickness of the first active layer; and/or the thickness of the first portion of the second active layer is greater than the thickness of the second portion.
3. The pole piece of claim 1, wherein the width of the first groove is the same as the width of the current collector.
4. The pole piece of claim 1, wherein a vertical projection area of the second groove on the current collector is 1% -50% of a vertical projection area of the first groove on the current collector.
5. The pole piece according to any one of claims 1 to 4, wherein the pole piece is a negative pole piece, the average particle size of the negative pole active material in the second active layer is 5-20 μm, and the graphitization degree is 90-98%.
6. The pole piece of claim 1, wherein the thickness of the first active layer is 5% to 80% of the total thickness of the second portions of the first and second active layers.
7. The pole piece of claim 1, wherein the width of the second groove is less than the width of the first groove along the width direction of the current collector.
8. The pole piece of claim 1 wherein the width of the second groove is 1-2 times the width of the tab connection area and the length of the second groove is 1-2 times the length of the tab connection area.
9. A lithium ion battery comprising a pole piece according to any one of claims 1 to 8.
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| CN202023314065.3U CN214672685U (en) | 2020-12-30 | 2020-12-30 | Pole piece and lithium ion battery |
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