CN217691222U - Battery cell structure unit and secondary battery - Google Patents
Battery cell structure unit and secondary battery Download PDFInfo
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- CN217691222U CN217691222U CN202221618135.0U CN202221618135U CN217691222U CN 217691222 U CN217691222 U CN 217691222U CN 202221618135 U CN202221618135 U CN 202221618135U CN 217691222 U CN217691222 U CN 217691222U
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- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
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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
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Abstract
The application provides a battery core structure unit and a secondary battery, wherein the battery core structure unit comprises a first pole piece laminated structure, a second pole piece and a separation film, the first pole piece laminated structure comprises more than two first pole pieces which are laminated, the first pole pieces comprise first current collectors and first active material layers arranged on at least one surfaces of the first current collectors, and the first current collectors are provided with porous structures penetrating along the thickness direction of the first current collectors; the second pole piece comprises a second current collector and a second active substance layer arranged on the surface of the second current collector; the isolation film is positioned between the first pole piece laminated structure and the second pole piece; wherein the first pole piece and the second pole piece have opposite polarities. The first pole piece and the second pole piece which are stacked in a multilayer mode are matched, so that the technical problem that the active material layer on the pole piece with the double-layer structure is too thick and is prone to demoulding is solved.
Description
Technical Field
The application relates to the technical field of batteries, in particular to a battery cell structural unit and a secondary battery.
Background
With the progress of technology, secondary batteries are widely used in the fields of electric vehicles, energy storage base stations, 3C products, and the like, and along with the demand of various products for improving energy density, the design and manufacture of high-energy-density electrodes have also become research hotspots.
In order to continuously increase the energy density of the device, the active material ratio can be increased by adopting a method of a thick electrode with a double-layer structure. However, the thickness of the active material layer on the double-layer structure pole piece is too large, which easily causes separation between two adjacent active material layers and between the active material layer and the current collector, and causes stripping, thereby greatly affecting the manufacturing and service life of the secondary battery.
SUMMERY OF THE UTILITY MODEL
The application provides a battery core structural unit and a secondary battery to solve the technical problem that the active material layer in a thick electrode with a double-layer structure is too thick and easy to demould.
The application provides a battery core structure unit, which comprises a first pole piece laminated structure, a second pole piece and an isolating membrane, wherein the first pole piece laminated structure comprises more than two first pole pieces which are laminated, the first pole pieces comprise a first current collector and a first active substance layer arranged on at least one surface of the first current collector, and the first current collector is provided with a porous structure penetrating along the thickness direction of the first current collector; the second pole piece comprises a second current collector and a second active substance layer arranged on the surface of the second current collector; the isolation film is positioned between the first pole piece laminated structure and the second pole piece; wherein the first pole piece and the second pole piece have opposite polarities.
Optionally, when the first pole piece is a positive pole piece and the second pole piece is a negative pole piece, a ratio of the capacity of the second pole piece to the capacity of the laminated structure of the first pole piece is 1.05-1.2; or the first pole piece is a negative pole piece, the second pole piece is a positive pole piece, and the ratio of the capacity of the laminated structure of the first pole piece to the capacity of the second pole piece is 1.05-1.2.
Optionally, the plurality of first pole piece lamination structures, the plurality of isolation films, and the plurality of second pole pieces are sequentially and alternately stacked to form a cell structure unit; or the first pole piece laminated structure, the isolating films and the second pole pieces are alternately laminated in sequence and then wound to form the battery cell structure unit.
Optionally, the first active material layer is disposed on the surface of the same side of the first pole piece at two ends of the first pole piece stacking structure in the stacking direction, and the first active material layer is disposed on two surfaces or one surface of the rest of the first pole pieces.
Optionally, the pore diameter of the porous structure on the first current collector is 50nm-500nm; when the first pole piece is a positive pole piece, the thickness of the first current collector is 6-15 μm; when the first pole piece is a negative pole piece, the thickness of the first current collector is 3-12 μm; the thickness of the second current collector is 4-16 μm.
Optionally, the surface of the second current collector is provided with protrusions and/or grooves.
Optionally, the thickness of the first active material layer on one side is H 1 The thickness of the second active material layer on one side is H 2 H is not less than 0.1 1 /H 2 ≤5。
Correspondingly, the application also provides a secondary battery, which comprises at least one battery cell structure unit, a first tab and a second tab, wherein the battery cell structure unit is any one of the battery cell structure units, and the first tab is connected to the first current collector; the second tab is connected to the second current collector.
Optionally, the secondary battery includes two or more of the battery cell structural units, and the two or more of the battery cell structural units are stacked in the thickness direction thereof or arranged side by side in the width direction thereof.
Optionally, more than two battery cell structure units are stacked along the thickness direction; each battery cell structure unit is in along its thickness direction one end the surface of first pole piece form the coating district that has the first active material layer of coating, each battery cell structure unit is in along its thickness direction other end the surface of first pole piece form the blank area that does not coat the first active material layer, adjacent two battery cell structure unit the coating district with blank area is connected.
The application provides a battery core constitutional unit and secondary battery, the polarity of first pole piece is opposite with the polarity of second pole piece in the battery core constitutional unit, utilizes to pile up the first pole piece of placing, and the first active material layer of coating on a plurality of first pole pieces can reduce the coating volume on the first active material layer in each first pole piece under the condition that total coating volume is the same to avoid the too big problem that leads to the pole piece to come off the membrane of first pole piece coating volume.
The first pole pieces comprise a first current collector and a first active material layer, and the first current collector is provided with a porous structure, so when the plurality of first pole pieces are sequentially stacked, lithium ions can freely move among the plurality of first pole pieces through the porous structure, the plurality of first pole pieces form a parallel structure, a second pole piece is matched with the plurality of first pole pieces, the plurality of first pole pieces are connected in parallel in each cell structure unit, the first active material layer is dispersedly coated on the plurality of first pole pieces, the coating amount of a single pole piece can be reduced, and the problem that the active material coating is too thick due to the overlarge coating amount of the pole pieces, and then the pole pieces are stripped is solved; meanwhile, the parallel connection of the plurality of first pole pieces can reduce the current of each pole piece, reduce the charge-discharge current of a single first pole piece in the working process of the lithium ion battery and improve the charge-discharge capacity of the battery cell; the dynamic performance of the secondary battery is improved, and the cost of the secondary battery is reduced.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.
Fig. 1 is a schematic diagram of a cell structure unit provided herein;
fig. 2 is a schematic combination diagram of a cell structure unit provided in the present application;
fig. 3 is a schematic diagram of arrangement of the cell structural units provided in the present application along the thickness direction thereof;
fig. 4 is a schematic diagram of arrangement of the cell structure units provided by the present application along the width direction thereof.
Description of reference numerals:
100. a first pole piece; 110. a first current collector; 120. a first active material layer; 200. a second pole piece; 210. a second current collector; 220. a second active material layer; 300. an isolation film; 410. a first tab; 420. and a second tab.
Detailed Description
The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application. Furthermore, it should be understood that the detailed description and specific examples, while indicating exemplary embodiments of the invention, are given by way of illustration and explanation only, and are not intended to limit the scope of the invention. In this application, unless stated to the contrary, the use of directional terms such as "upper", "lower", "left" and "right" generally refer to the upper, lower, left and right sides of the device in actual use or operation, and specifically to the orientation of the drawing figures.
The present application provides a battery cell structure unit, a secondary battery, and an electric device, which will be described in detail below. It should be noted that the following description of the embodiments is not intended to limit the preferred order of the embodiments of the present application. In the following embodiments, the description of each embodiment has its own emphasis, and reference may be made to the related description of other embodiments for parts that are not described in detail in a certain embodiment.
Referring to fig. 1 to 4, the present application provides a secondary battery including, but not limited to, any one of a lithium ion battery, a sodium ion battery, a magnesium ion battery, an aluminum ion battery, a capacitor, a super capacitor, and a pseudo capacitor. In the present application, a secondary battery is taken as an example of a lithium ion battery for analysis.
The secondary battery comprises a first tab 410, a second tab 420 and at least one cell structural unit a, wherein the first tab 410 is connected to the first current collector 110; the second tab 420 is connected to the second current collector 210. In this application, the first tab 410 is a positive tab, and the second tab 420 is a negative tab.
The secondary battery only comprises a battery cell structure unit A, and the battery cell structure unit A can be a winding battery cell or a laminated battery cell.
The secondary battery comprises more than two battery cell structural units A, and the battery cell structural units A are stacked along the thickness direction of the battery cell structural units A or are arranged side by side along the width direction of the battery cell structural units A to form a battery cell body. When the cell structure unit a is a winding cell, the cell structure units a may form a series structure or a parallel structure regardless of whether the cell structure units a are stacked in a thickness direction or formed in a width direction side by side. When the battery cell structure unit a is a laminated battery cell, a plurality of battery cell structure units a form a parallel structure along the thickness direction thereof, and a plurality of battery cell structure units a can form a parallel structure or a series structure along the width direction thereof. And when the battery cell structure unit A forms a parallel structure, the positive pole lug in the battery cell structure unit A is connected with the positive pole lug in the adjacent battery cell structure unit A, and the negative pole lug in the battery cell structure unit A is connected with the negative pole lug in the adjacent battery cell structure unit A. When the battery cell structure unit A forms a series structure, a positive pole lug in the battery cell structure unit A is connected with a negative pole lug in the adjacent battery cell structure unit A, and meanwhile, the negative pole lug in the battery cell structure unit A is connected with the positive pole lug in the adjacent battery cell structure unit A.
The battery cell structure unit a includes a first pole piece stacked structure, a second pole piece 200, and a separation film 300, where the first pole piece stacked structure includes two or more stacked first pole pieces 100, each first pole piece 100 includes a first active material layer 120 and a first current collector 110 provided with a porous structure, and the first active material layer 120 is coated on at least one surface of the first current collector 110, and the porous structure penetrates through the first current collector 110 in a thickness direction. The second pole piece 200 includes a second current collector 210 and a second active material layer 220, and the second active material layer 220 is coated on the surface of the second current collector 210. The polarity of the first pole piece 100 is opposite to that of the second pole piece 200, that is, when the first pole piece 100 is a positive pole piece, the second pole piece 200 is a negative pole piece; when the first pole piece 100 is a negative pole piece, the second pole piece 200 is a positive pole piece. A separator 300 is located between the first pole piece stack and the second pole piece 200 to separate the first pole piece 100 from the second pole piece 200 such that the positive pole is at a high potential and the negative pole is at a low potential, thereby creating a voltage difference.
Since the first pole piece 100 includes the first current collector 110 and the first active material layer 120, and the first current collector 110 has a porous structure, when a plurality of first pole pieces 100 are stacked in sequence, lithium ions can freely move between the plurality of first pole pieces 100 through the porous structure, so that the plurality of first pole pieces 100 form a parallel structure, and one second pole piece 200 is matched with the plurality of first pole pieces 100, thereby reducing the number of the second current collectors 210 and the separators 300, improving the dynamic performance of the secondary battery, and reducing the cost of the secondary battery.
In one embodiment, when the first electrode sheet 100 is a positive electrode sheet and the second electrode sheet 200 is a negative electrode sheet, the first current collector 110 has a porous structure, so that lithium ions can freely move between the first electrode sheets 100 (positive electrode sheets) stacked in multiple layers; by properly increasing the thickness of the second active material layer 220 in the second pole piece 200, a second pole piece 200 (negative pole piece) and a plurality of first pole pieces 100 (positive pole pieces) are matched with each other, so that the number of second current collectors 210 (negative pole current collectors) and isolating films 300 can be reduced, and the energy density of the battery cell is improved.
At this time, the plurality of first pole pieces 100 stacked form a parallel structure, so that the current of each first pole piece 100 (positive pole piece) can be reduced, and the current of positive charging and discharging in the working process of a secondary battery (lithium ion battery) can be reduced, thereby improving the charging and discharging capacity of a battery cell.
Further, the first pole piece lamination structure, the isolation film 300 and the second pole piece 200 are wound to form the cell structure unit a. When the cell structure unit a is a winding cell, the plurality of first pole pieces, the plurality of isolation films 300, and the plurality of second pole pieces 200 are sequentially and alternately stacked and then wound to form the cell structure unit a.
Further, two first pole piece laminated structures are provided, and two isolating films 300 are provided; a first pole piece laminated structure, an isolation film 300, a second pole piece 200, another isolation film 300, and another first pole piece laminated structure are laminated in sequence to form a cell structure unit a.
When the above-mentioned a plurality of battery cell structural units a are stacked along its thickness direction and set up, each battery cell structural unit a forms the coating area coated with first active material layer 120 on the surface of first pole piece 100 along its thickness direction one end, and each battery cell structural unit a forms the blank area not coated with first active material layer 120 on the surface of first pole piece 100 along its thickness direction other end, and the coating area and the blank area of two adjacent battery cell structural units a are connected to reduce battery cell structural unit a's coating thickness.
Since each first electrode sheet 100 includes the first active material layer 120 and the first current collector 110 with a porous structure, the number of the first active material layers 120 may be one layer or two layers, and the first electrode sheet 100 including two layers of the first active material layers 120 is defined as a first coating electrode sheet (in this embodiment, the first coating electrode sheet is the first positive electrode sheet 100 a), and the first electrode sheet 100 including one layer of the first active material layer 120 is defined as a second coating electrode sheet (in this embodiment, the second coating electrode sheet is the second positive electrode sheet 100 b). In the first positive electrode sheet 100a, two first active material layers 120 are respectively coated on two surfaces of the first current collector 110; in the second positive electrode tab 100b, a first active material layer 120 is coated on one surface of the first current collector 110.
When the first pole pieces 100 are all the first positive pole pieces 100a, the plurality of first positive pole pieces 100a are stacked in sequence and can be stacked on one side or two sides of the negative pole piece; when the first pole pieces 100 are all the second positive pole pieces 100b, a plurality of the second positive pole pieces 100b are stacked in sequence and can be stacked on one side or two sides of the negative pole piece; meanwhile, when a part of the first pole piece 100 is the first positive pole piece 100a and the rest of the first pole piece 100 is the second positive pole piece 100b, the first positive pole piece 100a and the second positive pole piece 100b are stacked and may be stacked on one side or both sides of the negative pole piece.
In a more preferred embodiment, the first pole piece in the middle of the first pole piece lamination structure may be the first positive pole piece 100a, and may also be the second positive pole piece 100b, and the first pole piece in the end of the first pole piece lamination structure is preferably the second positive pole piece 100b. In this embodiment, the first positive electrode sheet 100a and the second positive electrode sheet 100b are stacked on two sides of the negative electrode sheet, the first positive electrode sheet 100a is located in the middle of the first electrode sheet stacked structure, and the second positive electrode sheet 100b is located at the most end of the first electrode sheet stacked structure.
Taking a conventional roll core structure with 60 layers as an example, the first pole piece 100 (positive pole piece) is 60 layers, the second pole piece 200 (negative pole piece) is 61 layers, and the isolation film 300 is 124 layers (including a half of the outermost separator is wound). And in this application the number of layers of first pole piece 100 (positive pole piece) is 60 layers in the electric core body, and second pole piece 200 (negative pole piece) is 180 layers, and barrier film 300 is 122 layers (including the empty round of rolling up of outer lane diaphragm), and this application electric core body needs 60 electric core constitutional unit A to constitute can. Therefore this application compares in traditional roll core structure, need 60 constitutional unit A in this embodiment constitute can, compare in traditional roll core structure, the number of piles increase of second pole piece 200 (negative pole piece) is 3 times original, other remain unchanged. Therefore, the thickness of the second pole piece 200 (negative pole piece) of the winding core in the application is 1/3 (under the same cell capacity premise) of the traditional winding core negative pole thickness, and the negative pole dynamics is promoted, so that the cell dynamics performance can be greatly promoted.
41 layers of second current collectors 210 (negative current collectors) and 82 layers of isolating films 300 can be saved, so that the energy density of the cell is greatly improved.
Further, when the first pole piece 100 is a positive pole piece and the second pole piece 200 is a negative pole piece, the ratio of the capacity of the area of the second pole piece 200 facing the first pole piece 100 is 1.05-1.2. By limiting the capacity ratio of the first pole piece 100 to the second pole piece 200 to conform to the cell design principle, one second pole piece 200 is matched with a plurality of first pole pieces 100, the number of second current collectors 210 (negative current collectors) and isolating films 300 can be reduced, and the energy density of the secondary battery is improved; meanwhile, the thickness of the positive electrode plate can be reduced, and the two first active material layers 120, the first active material layer 120 and the first current collector 110 are prevented from being separated to cause demoulding.
Further, the first current collector 110 is a porous structure, and the pore diameter of the first current collector 110 is 50nm to 500nm, so that lithium ions can freely move between the multilayer first pole piece 100 through the porous structure, so as to match the multilayer first pole piece 100 with a second pole piece 200, reduce the number of the second current collectors 210 (negative current collectors) and the separators 300, and improve the cell energy density. The porous structure of the first current collector 110 in the present application includes various forms of a film, a sheet, a foil, a net, a porous body, a foam, or a non-woven fabric.
When the pore diameter of the first current collector 110 is 500nm, the migration effect of lithium ions among the multiple layers of the first pole pieces 100 is good; when the aperture of the first current collector 110 is 50nm, the migration effect of lithium ions between the multilayer first pole pieces 100 is slightly lower, so as to gradually increase the aperture of the first current collector 110, the migration effect of lithium ions between the multilayer first pole pieces 100 is improved, and simultaneously the strength of the first current collector 110 is gradually reduced, so that the strength requirement of the first pole piece 100 during preparation is improved. The pore diameter of the first current collector 110 in the present application is preferably about 300nm to balance the migration effect of lithium ions and the strength requirement of the first pole piece 100.
Further, when the first pole piece 100 is a positive pole piece, the thickness of the first current collector 110 is 6 μm to 15 μm, and the thickness of the second current collector 210 is 4 μm to 16 μm, so that the ratio of the capacity of the first pole piece 100 to the capacity of the second pole piece 200 meets the design principle of the battery cell, and the problem of demoulding due to the excessively thick electrode pole piece is avoided.
When the thickness of the first current collector 110 is 6 μm, the migration effect of lithium ions between the multiple layers of the first pole pieces 100 is better, and when the thickness of the first current collector 110 is 15 μm, the migration effect of lithium ions between the multiple layers of the first pole pieces 100 is slightly lower, so as to gradually decrease the thickness of the first current collector 110, improve the migration effect of lithium ions between the multiple layers of the first pole pieces 100, and gradually decrease the strength of the first current collector 110, so that the strength requirement of the first pole pieces 100 during preparation is improved. The thickness of the first current collector 110 in this application can be gradually reduced from the inner layer to the outer layer, so as to balance the lithium ion migration effect and the strength requirement of the first pole piece 100.
When the thickness of the second current collector 210 is gradually reduced, the strength of the second current collector 210 is gradually reduced, so that the strength requirement for the second pole piece 200 during manufacturing is increased, and therefore, the thickness of the second current collector 210 in the present application is preferably 10 μm.
Further, the thickness of the first active material layer on one side is H 1 The thickness of the second active material layer on one side is H 2 And 0.1 is less than or equal to H 1 /H 2 ≦ 5, thereby limiting the thickness of the first active material layer and the second active material layer.
Thickness H of first active material layer on one side 1 In the range of 50 mu m or less H 1 Less than or equal to 200 mu m, thereby avoiding the overlarge thickness of the active material in the cell structure unit for the thickness of the first active material layer and the second active material layer.
When the thickness H of the first active material layer on one side 1 At 50 μm, the energy density of the cell structural unit is slightly lower, while the thickness of the active material in the cell structural unit is smaller. Thickness H of the first active material layer on one side 1 At 200 μm, the energy density of the cell structural unit is high, and the thickness of the active material in the cell structural unit is largeIs relatively large. Thickness H of single-sided first active material layer in the present application 1 And 125 μm, to balance the energy density of the cell structural unit with the thickness of the active material.
Further, the surface of the second current collector 210 is provided with fine protrusions and/or grooves, and the adhesion of the electrode active material in the second pole piece 200 (negative pole piece), that is, the adhesion of the material of the second active material layer 220, can be improved by using the fine protrusions and grooves. The second current collector 210 may be formed with fine protrusions and/or grooves in various forms such as a film, a sheet, a foil, a net, a porous body, a foam, and a non-woven fabric.
Further, when the first electrode sheet 100 is a positive electrode sheet and the second electrode sheet 200 is a negative electrode sheet, the material of the first active material layer 120 includes at least one of lithium cobaltate, lithium manganate, lithium iron phosphate, and ternary lithium materials. The material of the second active material layer 220 includes at least one of graphite, hard carbon, soft carbon, silicon carbon, and lithium titanate.
In addition, the first current collector 110 may include aluminum, nickel, stainless steel, titanium, sintered carbon, surface-treated copper, stainless steel, or an alloy of the above elements. The second current collector 210 may include copper, nickel, stainless steel, titanium, sintered carbon, surface treated aluminum, stainless steel, or alloys of the above elements.
Further, the material of the first current collector 110 and the material of the second current collector 210 both include conductive carbon and a binder; the conductive carbon material comprises at least one of carbon black, acetylene black, a conductive agent, graphene, a carbon nano tube, a carbon nano wire, a carbon micro-sphere, a carbon fiber and graphene. The material of the binder comprises at least one of carboxymethyl cellulose, sodium carboxymethyl cellulose, lithium carboxymethyl cellulose, polyacrylic acid, sodium polyacrylate, styrene-butadiene rubber, polyethylene oxide, polyester, polyamide and polymethyl methacrylate.
Further, the material of the separation film 300 includes at least one of polypropylene and polyethylene.
Example two
Referring to fig. 1 to 4, in the present embodiment, the battery cell structure unit a includes more than two first pole pieces 100 and a second pole piece 200, where the first pole piece 100 is a negative pole piece, and the second pole piece 200 is a positive pole piece. Since the first current collector 110 has a porous structure, lithium ions can freely move between the first electrode sheets 100 (negative electrode sheets) stacked in multiple layers. At this time, the plurality of first pole pieces 100 stacked form a parallel structure, so that the current of each first pole piece 100 (negative pole piece) can be reduced, the negative discharge current of the secondary battery (lithium ion battery) during operation can be reduced, and the charge and discharge capacity of the battery cell can be improved. In addition, the thickness of the first active material layer 120 (i.e. the coating amount of the first active material layer 120) in each negative electrode sheet can be reduced by stacking the plurality of first electrode sheets 100 (negative electrode sheets), thereby avoiding the problem of demolding of the negative electrode sheets caused by the excessive thickness of the first active material layer 120.
Further, the first pole piece lamination structure, the isolation film 300 and the second pole piece 200 are wound to form the cell structure unit a. When the cell structure unit a is a winding cell, the plurality of first pole pieces, the plurality of isolation films 300, and the plurality of second pole pieces 200 are alternately stacked and then wound to form the cell structure unit a.
Further, two first pole piece laminated structures are provided, and two isolating films 300 are provided; a first pole piece laminated structure, an isolation film 300, a second pole piece 200, another isolation film 300, and another first pole piece laminated structure are laminated in sequence to form a cell structure unit a.
The first pole piece lamination structure, the isolation film 300 and the second pole piece 200 are laminated in sequence to form a double-layer structure.
When the cell structure unit a is a laminated cell, the cell structure unit a at least includes two double-layer structures and two isolation films 300, and the two double-layer structures are located between the two isolation films 300. When a plurality of above-mentioned electric core constitutional units a stack the setting along its thickness direction, each electric core constitutional unit a forms the coating district that coats with first active material layer 120 at the surface of first pole piece 100 along its thickness direction one end, and each electric core constitutional unit a forms the blank area that does not coat first active material layer 120 at the surface of first pole piece 100 along its thickness direction other end, and two adjacent electric core constitutional units a's coating district is connected with blank area to reduce electric core constitutional unit a's coating thickness.
Since each first electrode piece 100 includes the first active material layer 120 and the first current collector 110 with a porous structure, the number of the first active material layers 120 may be one or two, and the first electrode piece 100 including two first active material layers 120 is defined as a first coating electrode piece (in this embodiment, the first coating electrode piece is the first negative electrode piece 100 c), and the first electrode piece 100 including one first active material layer 120 is defined as a second coating electrode piece (in this embodiment, the second coating electrode piece is the second negative electrode piece 100 d). In the first negative electrode tab 100c, two first active material layers 120 are respectively coated on two surfaces of the first current collector 110; in the second negative electrode tab 100d, a first active material layer 120 is coated on a surface of the first current collector 110.
When the first pole pieces 100 are all the first negative pole pieces 100c, a plurality of the first negative pole pieces 100c are stacked in sequence, and can be stacked on one side or both sides of the second pole piece 200 (positive pole piece); when the first pole pieces 100 are all the second negative pole pieces 100d, a plurality of the second negative pole pieces 100d are stacked in sequence and can be stacked on one side or two sides of the positive pole piece; meanwhile, when a part of the first pole piece 100 is the first negative pole piece 100c and the rest of the first pole pieces 100 are the second negative pole pieces 100d, the first negative pole piece 100c and the second negative pole piece 100d are stacked and can be stacked on one side or two sides of the positive pole piece.
In a more preferred embodiment, the first pole piece in the middle of the first pole piece lamination structure may be the first negative pole piece 100c, and may also be the second negative pole piece 100d, and the first pole piece at the end of the first pole piece lamination structure is preferably the second negative pole piece 100d. In this embodiment, the first negative electrode tab 100c and the second negative electrode tab 100d are stacked on two sides of the positive electrode tab, the first negative electrode tab 100c is located in the middle of the first tab stacked structure, and the second negative electrode tab 100d is located at the end of the first tab stacked structure.
Taking a conventional roll core structure with 60 layers as an example, the positive electrode sheet has 60 layers, the negative electrode sheet has 61 layers, and the isolation film 300 has 124 layers (including one empty winding of the outermost separator). Under the same positive and negative pole piece number of layers condition, second pole piece 200 (positive pole piece) is 60 layers in this application, and first pole piece 100 (negative pole piece) is 180 layers, and barrier film 300 is 122 layers (contains the empty circle of rolling up of outer lane diaphragm), and it can to need 60 electric core constitutional unit A to constitute. Cell structure unit A compares in traditional roll core structure in this application, and the number of piles of first pole piece 100 (negative pole piece) increases for 3 times original, and other remain unchanged to the thickness of first pole piece 100 (negative pole piece) is the traditional 1/3 (under the same electric core capacity prerequisite) of rolling up core negative pole thickness in the electric core body of this application, makes negative pole dynamic property obtain promoting, in order to promote electric core dynamic property by a wide margin.
Further, when the first pole piece 100 is a negative pole piece and the second pole piece 200 is a positive pole piece, the ratio of the capacity of the first pole piece 100 to the capacity of the second pole piece 200 is 1.05-1.2. The capacity ratio of the first pole piece 100 to the second pole piece 200 is defined to meet the design principle of the battery cell, so that the thickness of the first active material layer 120 can be reduced by matching one second pole piece 200 with a plurality of first pole pieces 100, and the two first active material layers 120 and the demoulding caused by the separation between the first active material layer 120 and the first current collector 110 are avoided. Meanwhile, the parallel structure formed by stacking the multiple first pole pieces 100 (negative pole pieces) can reduce the current of each negative pole piece, reduce the negative charge-discharge current in the working process of the secondary battery, and improve the charge-discharge capacity of the battery core.
Further, the first current collector 110 is a porous structure, and the pore diameter of the first current collector 110 is 50nm to 500nm, so that lithium ions can freely move between the multiple layers of first pole pieces 100, and the multiple layers of first pole pieces 100 are matched with a second pole piece 200, so as to reduce the current of each first pole piece 100 (negative pole piece), reduce the negative charge and discharge current in the secondary battery operation, and improve the charge and discharge capacity of the battery cell. Meanwhile, the thickness of the first active material layer 120 can be reduced, and the two first active material layers 120 and the first active material layer 120 and the first current collector 110 are prevented from being separated from each other to cause demolding. The porous structure of the first current collector 110 in the present application includes various forms such as a film, a sheet, a foil, a net, a porous body, a foam or a non-woven fabric.
For the first current collectors 110 with the same surface area, when the pore diameter of the first current collector 110 is 500nm, the migration effect of lithium ions between the multiple layers of first pole pieces 100 is better; when the aperture of the first current collector 110 is 50nm, the migration effect of lithium ions between the multilayer first pole pieces 100 is slightly lower, so as to gradually increase the aperture of the first current collector 110, the migration effect of lithium ions between the multilayer first pole pieces 100 is improved, and simultaneously the strength of the first current collector 110 is gradually reduced, so that the strength requirement of the first pole piece 100 during preparation is improved. The pore diameter of the first current collector 110 in this application is preferably about 300nm to balance the lithium ion migration effect and the strength requirement of the first pole piece 100.
Further, when the first pole piece 100 is a negative pole piece, the thickness of the first current collector 110 is 3 μm to 12 μm, and the thickness of the second current collector 210 is 4 μm to 16 μm, so that the ratio of the capacity of the first pole piece 100 to the capacity of the second pole piece 200 meets the design principle of the battery cell, and the problem of demoulding due to the excessively thick electrode pole piece is avoided.
When the thickness of the first current collector 110 is 3 μm, the migration effect of lithium ions between the multiple layers of the first pole pieces 100 is better, and when the thickness of the first current collector 110 is 12 μm, the migration effect of lithium ions between the multiple layers of the first pole pieces 100 is slightly lower, so as to gradually decrease the thickness of the first current collector 110, improve the migration effect of lithium ions between the multiple layers of the first pole pieces 100, and gradually decrease the strength of the first current collector 110, thereby improving the strength requirement of the first pole pieces 100 during preparation. The thickness of the first current collector 110 in this application can be gradually reduced from the inner layer to the outer layer, so as to balance the lithium ion migration effect and the strength requirement of the first pole piece 100.
When the thickness of the second current collector 210 is gradually reduced, the strength of the second current collector 210 is gradually reduced, so that the strength requirement of the second pole piece 200 during preparation is improved, and therefore the thickness of the second current collector 210 in the present application is preferably 10 μm.
Further, the thickness of the first active material layer on one side is H 1 The thickness of the second active material layer on one surface is H 2 And 0.1 is less than or equal to H 1 /H 2 ≦ 5, thereby limiting the thickness of the first active material layer and the second active material layer.
Thickness H of first active material layer on one side 1 In the range of 50 mu m or less H 1 Less than or equal to 200 mu m, thereby avoiding the overlarge thickness of the active material in the cell structure unit for the thickness of the first active material layer and the second active material layer.
Thickness H of the first active material layer on one side 1 At 50 μm, the energy density of the cell structural unit is slightly lower, while the thickness of the active material in the cell structural unit is smaller. Thickness H of the first active material layer on one side 1 At 200 μm, the energy density of the cell structural unit is high, while the thickness of the active material in the cell structural unit is large. Thickness H of single-sided first active material layer in the present application 1 Is 125 μm, thereby balancing the energy density of the cell structural unit with the thickness of the active material.
Further, the surface of the second current collector 210 is provided with fine protrusions and/or grooves, and the fine protrusions and grooves can improve the adhesion of the electrode active material in the positive electrode tab, that is, the adhesion of the material of the second active material layer 220. The second current collector 210 may be formed with fine protrusions and/or grooves in various forms such as a film, a sheet, a foil, a net, a porous body, a foam, and a non-woven fabric.
Further, when the first electrode sheet 100 is a negative electrode sheet and the second electrode sheet 200 is a positive electrode sheet, the material of the first active material layer 120 includes at least one of graphite, hard carbon, soft carbon, silicon carbon, and lithium titanate. The material of the second active material layer 220 includes at least one of lithium cobaltate, lithium manganate, lithium iron phosphate, and ternary lithium material.
In addition, the first current collector 110 may include copper, nickel, stainless steel, titanium, sintered carbon, surface-treated aluminum, stainless steel, or an alloy of the above elements. The second current collector 210 may include aluminum, nickel, stainless steel, titanium, sintered carbon, surface treated copper, stainless steel, or alloys of the above elements.
Further, the material of the first current collector 110 and the material of the second current collector 210 both include conductive carbon and a binder; the conductive carbon material comprises at least one of carbon black, acetylene black, a conductive agent, graphene, a carbon nano tube, a carbon nano wire, a carbon micro-sphere, a carbon fiber and graphene. The material of the binder comprises at least one of carboxymethyl cellulose, sodium carboxymethyl cellulose, lithium carboxymethyl cellulose, polyacrylic acid, sodium polyacrylate, styrene-butadiene rubber, polyethylene oxide, polyester, polyamide and polymethyl methacrylate.
Further, the material of the separation film 300 includes at least one of polypropylene and polyethylene. The above provides a cell structure unit, a secondary battery and an electric device, and a specific example is applied in the description to explain the principle and the implementation of the present application, and the description of the above embodiment is only used to help understand the method and the core idea of the present application; meanwhile, for a person skilled in the art, according to the idea of the present application, there may be variations in the specific embodiments and the application scope, and in summary, the content of the present specification should not be construed as a limitation to the present application.
Claims (10)
1. A cell structure unit, comprising:
the first pole piece lamination structure comprises more than two first pole pieces which are arranged in a lamination mode, the first pole pieces comprise first current collectors and first active substance layers arranged on at least one surfaces of the first current collectors, and the first current collectors are provided with porous structures penetrating through the first current collectors in the thickness direction;
the second pole piece comprises a second current collector and a second active substance layer arranged on the surface of the second current collector; and
a separator between the first and second pole piece stack structures;
wherein the first pole piece and the second pole piece have opposite polarities.
2. The cell construction unit according to claim 1,
the first pole piece is a positive pole piece, the second pole piece is a negative pole piece, and the ratio of the capacity of the second pole piece to the capacity of the laminated structure of the first pole piece is 1.05-1.2; or
The first pole piece is a negative pole piece, the second pole piece is a positive pole piece, and the ratio of the capacity of the laminated structure of the first pole piece to the capacity of the second pole piece is 1.05-1.2.
3. The cell construction unit of claim 1,
the first pole piece laminated structure, the isolation films and the second pole pieces are sequentially and alternately stacked to form a battery cell structure unit; or
And the first pole piece laminated structure, the isolation films and the second pole pieces are sequentially and alternately laminated and then wound to form a battery cell structure unit.
4. The cell structural unit according to claim 1, wherein the first active material layer is disposed on both surfaces of the first pole piece at both ends of the first pole piece lamination structure in the lamination direction, and the first active material layer is disposed on both surfaces or one surface of the remaining first pole pieces.
5. The cell construction unit of claim 1,
the pore diameter of the porous structure on the first current collector is 50nm-500nm;
when the first pole piece is a positive pole piece, the thickness of the first current collector is 6-15 μm;
when the first pole piece is a negative pole piece, the thickness of the first current collector is 3-12 μm;
the thickness of the second current collector is 4-16 μm.
6. The cell construction unit of claim 1,
and the surface of the second current collector is provided with a bulge and/or a groove.
7. The cell structural unit of claim 1, characterized by a single faceThe thickness of the first active material layer is H 1 The thickness of the second active material layer on one side is H 2 H is not less than 0.1 1 /H 2 ≤5。
8. A secondary battery, characterized by comprising:
at least one cell structural unit of any one of claims 1-7;
a first tab connected to the first current collector; and
a second tab connected to the second current collector.
9. The secondary battery according to claim 8, wherein the secondary battery includes two or more of the cell structural units, and the two or more of the cell structural units are stacked in a thickness direction thereof or arranged side by side in a width direction thereof.
10. The secondary battery according to claim 9, wherein two or more of the cell structural units are stacked in a thickness direction thereof;
each battery cell structure unit is in along its thickness direction one end the surface of first pole piece form the coating district that has the first active material layer of coating, each battery cell structure unit is in along its thickness direction other end the surface of first pole piece form the blank area that does not coat the first active material layer, adjacent two battery cell structure unit the coating district with blank area is connected.
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| CN202221618135.0U CN217691222U (en) | 2022-06-24 | 2022-06-24 | Battery cell structure unit and secondary battery |
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| CN202221618135.0U CN217691222U (en) | 2022-06-24 | 2022-06-24 | Battery cell structure unit and secondary battery |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117276637A (en) * | 2023-11-15 | 2023-12-22 | 珠海冠宇电池股份有限公司 | Battery cell and battery |
| WO2024182938A1 (en) * | 2023-03-03 | 2024-09-12 | 宁德时代新能源科技股份有限公司 | Electrode assembly, battery cell, battery and electric device |
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2022
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2024182938A1 (en) * | 2023-03-03 | 2024-09-12 | 宁德时代新能源科技股份有限公司 | Electrode assembly, battery cell, battery and electric device |
| CN117276637A (en) * | 2023-11-15 | 2023-12-22 | 珠海冠宇电池股份有限公司 | Battery cell and battery |
| CN117276637B (en) * | 2023-11-15 | 2024-05-17 | 珠海冠宇电池股份有限公司 | Battery cell and battery |
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Address after: 518000 1-2 Floor, Building A, Xinwangda Industrial Park, No. 18 Tangjianan Road, Gongming Street, Guangming New District, Shenzhen City, Guangdong Province Patentee after: Xinwangda Power Technology Co.,Ltd. Address before: 518107 1-2 Floor, Building A, Xinwangda Industrial Park, No. 18 Tangjianan Road, Gongming Street, Guangming New District, Shenzhen City, Guangdong Province Patentee before: SUNWODA ELECTRIC VEHICLE BATTERY Co.,Ltd. |
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