CN112117497A - Battery cell and battery cell forming method - Google Patents
Battery cell and battery cell forming method Download PDFInfo
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- CN112117497A CN112117497A CN202011071311.9A CN202011071311A CN112117497A CN 112117497 A CN112117497 A CN 112117497A CN 202011071311 A CN202011071311 A CN 202011071311A CN 112117497 A CN112117497 A CN 112117497A
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/058—Construction or manufacture
- H01M10/0585—Construction or manufacture of accumulators having only flat construction elements, i.e. flat positive electrodes, flat negative electrodes and flat separators
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
- H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
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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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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
- Y02P70/50—Manufacturing or production processes characterised by the final manufactured product
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Abstract
The invention discloses an electric core and an electric core forming method, wherein the electric core comprises a plurality of layers of pole piece groups, the plurality of layers of pole piece groups are stacked up and down, diaphragms are arranged between the adjacent pole piece groups for connection, the poles of the pole piece groups of the adjacent layers are different, and each layer of pole piece group comprises: pole pieces and pole lugs. The pole lugs are connected with the pole pieces and extend outwards; the extension length of the pole lugs is increased from the middle to the two sides, the pole lugs on the two sides are closed to the pole lug in the middle and are overlapped, and the end faces formed by the pole lugs of the pole piece group with the same polarity after overlapping are flush. According to the battery cell provided by the embodiment of the invention, for the multi-layer pole piece groups which are stacked, the middle pole lug has the shortest extension length, and the pole lugs on two sides have the longest extension length, so that after the multi-layer pole piece groups are stacked, the pole lugs on two sides are close to the middle pole lug and overlapped to form the whole end surface of the positive pole lug or the negative pole lug, and the end surface is flush without subsequent cutting, thereby avoiding metal dust generated when welding each layer of pole lug.
Description
Technical Field
The invention belongs to the technical field of battery manufacturing, and particularly relates to a battery core and a battery core forming method.
Background
The rapid development of new energy industries relies on the constant innovation of lithium ion battery technology.
The lithium ion battery may be in a wound form or a stacked form during the manufacturing process. For each single-layer battery cell, a hardware mould or laser cutting is adopted, a certain length is reserved to facilitate later-stage welding, the reserved length is completely equal to enable the lug end parts of all layers to be kept parallel and level, and then subsequent stacking or winding is carried out.
However, for the battery core formed by stacking, when the thickness of the battery core is large, the end part of the lug in the middle layer is farthest away from the battery core body, and the end part of the lug in the outermost layer is nearest to the battery core body, so that the welded lug is dislocated and the end part of the lug is not level, and the space waste is caused.
In order to make the utmost point ear tip after the welding flush, need cut the parallel and level once more to all utmost point ears, nevertheless utmost point ear cuts the in-process and can produce more metal dust, only can siphons away the dust on surface through the negative pressure dust absorption, and the adhesion can not effectively be clear away at near the dust of cutting off the mouth, and inside if near the dust of cutting off the mouth got into electric core, can seriously influence the self discharge performance of electric core.
Disclosure of Invention
The present invention is directed to solving at least one of the problems of the prior art. Therefore, the invention provides the battery cell, the end faces of the lugs of the battery cell are flush after the multilayer pole piece groups of the battery cell are stacked, secondary cutting is not needed, and the problem that the performance of the battery is affected by metal scraps generated by cutting the lugs in the stacking and forming process is solved.
The invention also aims to provide a battery cell forming method.
The battery cell comprises a plurality of layers of pole piece groups, wherein the plurality of layers of pole piece groups are stacked up and down, adjacent pole piece groups are connected by a diaphragm, the poles of the adjacent pole piece groups are different, and each layer of pole piece group comprises: pole pieces; the pole lug is connected with the pole piece and extends outwards; the extension length of the lugs is increased from the middle to the two sides, the lugs on the two sides are close to the middle lug and are overlapped, and the overlapped lugs are the same in polarity and the end faces formed by the lugs in the lug group are flush.
According to the battery cell provided by the embodiment of the invention, for the multi-layer pole piece groups which are stacked, the extension length of the middle pole lug is shortest, and the extension lengths of the pole lugs at two sides are longest, so that after the multi-layer pole piece groups are stacked, the pole lugs at two sides are close to the middle pole lug and overlapped to form the whole end surface of the positive pole lug or the negative pole lug, and the end surface is flush without subsequent cutting, thereby avoiding metal dust generated when welding each layer of pole lug.
According to the battery cell, the edges of the pole piece groups with the same polarity are arranged in an up-down alignment manner, each pole piece group comprises a positive pole piece group and a negative pole piece group with different polarities, each positive pole piece group comprises a positive pole piece body, an aluminum foil and a positive pole lug, and the aluminum foil is wrapped on the outer side of each positive pole piece body; the negative electrode plate group comprises a negative electrode plate body, a copper foil and a negative electrode lug, and the copper foil is wrapped on the outer side of the negative electrode plate body; the positive pole piece group and the negative pole piece group are alternately arranged, and the pole lugs of the same pole piece group are vertically aligned.
Optionally, when the number of the same pole piece group is an odd number of layers, the extension length of the pole lug of the pole piece group positioned in the middle part is shortest, and the extension lengths of the pole lugs are sequentially increased in the directions from the middle part to the two sides; when the number of the pole piece groups of the same kind is even, the extending lengths of the pole lugs of the two pole piece groups positioned in the middle are the same, and the extending lengths of the pole piece groups far away from the two sides of the middle pole piece group are sequentially increased.
The battery cell comprises at least seven layers of pole piece groups, wherein the two layers of pole piece groups positioned on the top side and the bottom side are both the negative pole piece groups, the one layer of pole piece group positioned in the middle part is the positive pole piece group, and the extending lengths of the positive pole ears of the two layers of positive pole piece groups with the same interval distance from the central plane of the positive pole piece group are the same; the two layers of the negative electrode tab groups with the same distance from the central plane have the same extension length of the negative electrode tabs.
Optionally, the thickness of each layer of positive plate body is the same and is recorded as z, the thickness of each layer of aluminum foil is the same and is recorded as e, the thickness of each layer of negative plate body is the same and is recorded as f, the thickness of each layer of diaphragm is the same and is recorded as g, the thickness of each layer of copper foil is the same and is recorded as d, the tab comprises a welding section and an even section, and the welding section is provided with a cell body end close to the plate and a welding seal inner end connected with the even section;
the length of the welding section of the positive plate group on the T-th layer positioned on the two sides is recorded as lT isThe height difference between the central plane of the positive electrode plate group of the middle layer and the central plane of the positive electrode plate group of the T-th layer at the two sides of the positive electrode plate group of the middle layer is recorded as hT is，lT isIs equal to the sum of the squares of c and hT isThe square sum of (1), wherein the welding section is in a stretched state; h isT is＝T*z+T*f+2*T*g-(T-1)*e；
The length of the welding section of the positive electrode plate group in the middle layer towards the T-th negative electrode plate groups on the two sides is recorded as lT is minusThe height difference between the central plane of the positive electrode plate group in the middle layer and the central plane of the negative electrode plate group in the T-th layer at the two sides from the central plane of the positive electrode plate group in the middle layer is recorded as hT is minus，lT is minusIs equal to the sum of the squares of c and hT is minusThe square sum of (1), wherein the welding section is in a stretched state; h isT is minus＝(T+0.5)*z+(T+0.5)*f+(2*T+1)*g-T*d。
Advantageously, the welding sections of the positive electrode plate groups on two sides have a certain radian and the length is lT is', at this time, "T is’＝α*lT isAlpha is more than 1 and less than or equal to 2; the welding sections of the cathode electrode plate groups positioned on the two sides have a certain radian and are l in lengthT is minus', at this time, "T is minus’＝β*lNegative plus，1＜β≤2。
According to the battery cell of one embodiment of the invention, the positive tab of the positive electrode tab group and the negative tab of the negative electrode tab group both extend out in the same direction and are located at the same side, and all the superposed positive tabs and all the superposed negative tabs are arranged at intervals in the horizontal direction.
According to the battery cell of one embodiment of the present invention, the positive tab of the positive electrode tab group and the negative tab of the negative electrode tab group extend out toward different sides.
The cell forming method provided by the embodiment of the invention comprises a plurality of layers of pole piece groups which are stacked, wherein each layer of pole piece group comprises a tab which extends outwards, and the cell forming method comprises the following steps: sequentially and alternately stacking the anode plate groups and the cathode plate groups with different polarities, wherein the edges of all the electrode plate groups are aligned; a layer of diaphragm is additionally arranged between the adjacent anode plate group and the adjacent cathode plate group; the tabs of the pole piece group positioned in the middle layer horizontally extend out and have the shortest extension length, and the extension lengths of the tabs of the pole piece group from the middle pole piece group to the two side directions are sequentially increased; welding positive lugs of the positive plate groups with the same polarity to form end faces which are parallel and level; and welding the negative electrode lugs of all the negative electrode plate groups to form end faces which are parallel and level.
According to the battery cell forming method provided by the embodiment of the invention, the positive pole piece groups and the negative pole piece groups with different polarities are sequentially and alternately stacked, the edges of the pole piece groups with the same pole piece are flush, the extending lengths of the pole lugs are sequentially increased from the middle layer to the edge layer, and finally the pole lugs with the same polarity are drawn close from two sides to the middle and welded to form the positive pole lug and the negative pole lug with flush end surfaces.
According to the battery cell forming method provided by the embodiment of the invention, after the layer of the negative electrode plate group is arranged at the bottommost layer, other electrode plate groups are stacked, and the layer of the negative electrode plate group is left at the topmost layer, the positive electrode plate group is positioned in the middle layer and at least three layers of positive electrode plate groups are stacked, and the formed battery cell is provided with at least seven layers of the electrode plate groups.
Additional aspects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.
Drawings
The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:
fig. 1 is a schematic structural diagram of a battery cell according to an embodiment of the present invention, in which tabs are in a stacked state.
Fig. 2 is a schematic structural diagram of a battery cell when the pole ear in fig. 1 is unfolded.
Fig. 3 is a schematic structural diagram of a battery cell according to another embodiment of the present invention, wherein tabs are in a stacked state.
Fig. 4 is a schematic structural diagram of the battery cell when the pole ear in fig. 3 is unfolded.
Fig. 5 is a comparison graph of cell voltage drop of the cells of the present application and the cells of the conventional process under the same test conditions.
Reference numerals:
an electric core 100,
A pole piece group 1,
A positive electrode plate group 11,
A positive plate body 111,
A first leveling section 1132,
A negative electrode plate group 12,
A negative electrode sheet body 121,
A negative electrode tab 123, a second welding section 1231, a second welding stamp inner end 12311, a second cell body end 12312,
A second parallel section 1232,
A diaphragm 2.
Detailed Description
Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention, and are not to be construed as limiting the present invention.
In the description of the present invention, it is to be understood that the terms "center", "longitudinal", "length", "width", "thickness", "upper", "lower", "vertical", "horizontal", "top", "bottom", and the like, indicate orientations or positional relationships based on those shown in the drawings, and are used only for convenience in describing the present invention and for simplicity in description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed in a particular orientation, and be operated, and thus, are not to be construed as limiting the present invention.
The battery cell 100 according to the embodiment of the present invention is described below with reference to the drawings.
As shown in fig. 1, the battery cell 100 according to an embodiment of the present invention includes a plurality of pole piece groups 1, the plurality of pole piece groups 1 are stacked up and down, a separator 2 is disposed between adjacent pole piece groups 1 for connection, and the pole piece groups 1 of adjacent layers have different polarities. The difference in polarity here refers to the difference in polarity between the positive electrode plate group 11 and the negative electrode plate group 12.
Each layer of the pole piece group 1 comprises: pole piece and utmost point ear, wherein, utmost point ear connection pole piece, and utmost point ear outwards stretches out. As shown in fig. 2 and 4, the protruding length of the tab increases from the middle to both sides. As shown in fig. 1 and fig. 3, the tabs on both sides are close to the tab in the middle and are overlapped, and the end surfaces formed by the tabs of the laminated pole piece group 1 with the same polarity are flush. Here, the tab of the pole piece group 1 having the same polarity refers to the positive tab 113 of all the positive pole piece groups 11 or the negative tab 123 of all the negative pole piece groups 12.
As can be seen from the above structure, in the battery cell 100 according to the embodiment of the present invention, for the stacked multiple layers of the pole piece groups 1, the protruding length of the middle tab is the shortest, the protruding length of the side tab farther from the middle tab is increased, and the protruding lengths of the two outermost tabs are the longest, so that after the multiple layers of the pole piece groups 1 are stacked, the tabs on the two sides are close to the middle tab and are overlapped to form the whole positive tab 113 or negative tab 123 with flush end surfaces, and subsequent cutting is not required, thereby preventing metal dust generated when welding the tabs on the respective layers from entering the battery cell, reducing the self-discharge level of the battery cell, and improving the uniformity of the battery.
It can be understood that, compared with the prior art in which each tab after stacking is cut again, the battery cell 100 of the present invention does not need to cut each tab after molding, but after each layer of the pole piece groups 1 are stacked, the tabs with the same polarity are stacked to automatically form the end faces flush with each other, so that the process is saved, and the self-discharge of the battery cell 100 is reduced.
In some embodiments of the present invention, as shown in fig. 2, the edges of the pole piece sets 1 with the same polarity are aligned up and down, the pole piece set 1 includes a positive pole piece set 11 and a negative pole piece set 12 with different polarities, the positive pole piece set 11 includes a positive pole piece body 111, an aluminum foil and a positive tab 113, the outer side of the positive pole piece body 111 is wrapped with the aluminum foil, and the aluminum foil is used as a positive pole current collector, which has good conductivity and light weight, and the surface of the aluminum foil can be passivated to prevent further oxidation. Correspondingly, the negative electrode plate group 12 comprises a negative electrode plate body 121, copper foil and a negative electrode tab 123, the copper foil is wrapped on the outer side of the negative electrode plate body 121 and serves as a negative electrode current collector, and the negative electrode plate group is good in conductivity, light in weight, good in toughness and stable in property.
Optionally, the positive electrode plate groups 11 and the negative electrode plate groups 12 are alternately arranged, and the tabs of the same type of plate group 1 are vertically aligned, so that the positive electrode tabs 113 with the same polarity are conveniently overlapped and welded together, and the negative electrode tabs 123 with the same polarity are also conveniently overlapped and welded together.
As shown in fig. 2 and 4, when the number of layers of the same pole piece group 1 is an odd number, the tab extending length of the pole piece group 1 located in the middle part is the shortest, and the extending lengths of the tabs increase gradually in the directions from the middle part to both sides. When the pole piece group 1 is the odd number layer, the one deck pole piece group 1 that is located the middle part is as the center, the utmost point ear of each layer pole piece group 1 of both sides all need draw close and overlap together with the utmost point ear in the middle towards the utmost point ear in the middle of, and because the pole piece group 1 all has certain thickness, consequently the utmost point ear of pole piece group 1 far away from the utmost point ear in intermediate level needs the more part of loss length to be close to the utmost point ear in intermediate level when the coincide, and accomplish coincide and weld, and the utmost point ear that this application was equipped with above-mentioned specific structure then can be after the coincide finishes, the automatic parallel and level. For example, in the positive electrode plate group 11 shown in fig. 2 and 4, the number of layers is odd, and thus the design structure is described above, and all the positive electrode tabs 113 are flush with each other after lamination.
Correspondingly, when the number of the layers of the same pole piece group 1 is even, the extending lengths of the pole lugs of the two pole piece groups 1 positioned in the middle are the same, and the extending lengths of the pole piece groups 1 at the two sides far away from the middle pole piece group 1 are sequentially increased. When the number of the pole piece groups 1 is even, the pole piece group 1 in the middle has two layers, and the central surfaces of the two layers of the pole piece groups 1 form a superposed symmetrical surface, so that the pole lugs of each layer of the pole piece groups 1 on the two sides are drawn together and superposed by the symmetrical surface, and finally the pole lug of the complete battery cell 100 is formed. For example, in the negative electrode plate group 12 in fig. 2 and 4, the number of layers is even, so that the design structure is as described above, and all the negative electrode tabs 123 are flush with each other after the lamination is completed.
Advantageously, as shown in fig. 1 and fig. 3, the battery cell 100 of the present invention includes at least seven layers of pole piece sets 1, where the two layers of pole piece sets 1 located at the top side and the bottom side are both negative pole piece sets 12, the one layer of pole piece set 1 located at the middle part is a positive pole piece set 11, and the protruding lengths of the positive pole ears 113 of the two layers of positive pole piece sets 11, which are spaced apart from the central plane by the same distance, are the same with each other; the negative electrode tabs 123 of the two layers of negative electrode plate groups 12 with the same distance from the central plane have the same extension length. That is to say, in the case that the battery cell 100 in the present application includes the seven-layer pole piece group 1 as shown in fig. 1 or includes more than seven-layer pole piece group 1 as shown in fig. 3, it is more obvious that the end part is not flush when the tabs with the same polarity are stacked, and the above problems can be overcome by using the design form of the pole piece group 1 and the tabs in the present application. The positive electrode plate group 11 of the present application is located in the middle layer, and the same kind of electrode plate groups 1 with the same distance and the same tab extending length are symmetrically stacked in sequence with the central plane of the positive electrode plate group 11 of the middle layer as a reference plane, so that the effect required by the finally stacked battery cell 100 of the present application can be achieved.
It should be noted that, in the actual lamination process, the electrode plate group 1 of the present application does not need to be laminated from the middle layer to both sides, but may be laminated in sequence from the bottom layer to the top layer.
It should be further noted that, in the present application, the negative electrode plate group 12 is located at the outermost layer, and the positive electrode plate group 11 is located at the intermediate layer, which is more suitable for the actual processing and production requirements, but if necessary, the negative electrode plate group 12 may also be located at the intermediate layer, and the positive electrode plate group 11 is located at both sides, which is not limited specifically here.
In some embodiments of the present invention, as shown in fig. 2, the thickness of each positive electrode sheet body 111 is the same and is denoted by z, the thickness of each aluminum foil is the same and is denoted by e, the thickness of each negative electrode sheet body 121 is the same and is denoted by f, the thickness of each separator 2 is the same and is denoted by g, the thickness of each copper foil is the same and is denoted by d, the tab includes a welded section and a flush section, and the welded section has a cell body end close to the electrode sheet and a welded inner end connected to the flush section.
Optionally, the cell body end refers to a flush end surface of the anode electrode plate group 11, the cathode electrode plate group 12 or the diaphragm 2 at the outermost end, and generally refers to a flush end surface of the diaphragm 2.
For convenience of description, in the following examples, the welding-together section and the flush section of the positive tab 113 are respectively denoted as a first welding-together section 1131 and a first flush section 1132, the inner end of the welding-print on the first welding-together section 1131 is denoted as a first welding-print inner end 11311, and the cell body end on the first welding-together section 1131 is denoted as a first cell body end 11312; the welding section and the flush section of the negative tab 123 are respectively denoted as a second welding section 1231 and a second flush section 1232, the inner end of the welding seal on the second welding section 1231 is denoted as a second inner welding seal 12311, and the end of the cell body on the second welding section 1231 is denoted as a second cell body end 12312.
As shown in fig. 3, the positive tab 113 of the positive electrode tab group 11 located in the middle layer horizontally protrudes, and the length of the first welded segment 1131 is denoted as c, and the lengths of the welded segments of the T-th positive electrode tab groups 11 located on both sides are denoted as lT isThe height difference between the central plane of the T-th layer positive electrode plate group 11 on both sides of the positive electrode plate group 11 in the middle layer and the central plane of the positive electrode plate group 11 in the middle layer is denoted as hT is，lT isIs equal to the sum of the squares of c and hT isIs the sum of squares of, i.e.The method comprises the following steps:
lt is 2＝c2+hT is 2Wherein the first welded segment 1131 is in a straightened state.
Furthermore, hT is＝T*z+T*f+2*T*g-(T-1)*e。
Similarly, the length of the second welding section 1231 from the positive electrode plate group 11 in the middle layer to the T-th negative electrode plate groups 12 on the two sides is recorded as lT is minusThe height difference between the center plane of the positive electrode plate group 11 in the middle layer and the center plane of the negative electrode plate group 12 in the T-th layer on both sides from the center plane of the positive electrode plate group 11 in the middle layer is denoted as hT is minus，lT is minusIs equal to the sum of the squares of c and hT is minusThe sum of the squares of (i) also means:
lt is minus 2＝c2+hT is minus 2Wherein the second welded segment 1231 is in a straightened state.
Furthermore, hT is minus＝(T+0.5)*z+(T+0.5)*f+(2*T+1)*g-T*d。
Optionally, the outward extending length of the positive tab 113 is 2-40 mm, and the outward extending length of the negative tab 123 is 2-40 mm, which can be selectively designed according to specific products.
Optionally, the difference Δ T between the tab extension length of the positive electrode plate group 11 of the T-th layer on both sides of the positive electrode plate group 11 of the intermediate layer and the extension length c of the positive electrode tab 113 of the intermediate layer is used as the positive electrode tab group 11 of the intermediate layerIs just＝lT is-c; similarly, the difference value Δ T between the tab extension length of the negative electrode plate group 12 of the T-th layer on both sides and the extension length of the positive electrode tab 113 of the intermediate layer is calculated by the negative electrode plate group 12 of the intermediate layerNegative pole＝lT is minus-c。
Optionally, the first welding section 1131 of the positive electrode plate group 11 on both sides has a certain radian and a length of lT is', at this time, "T is’＝α*lT isAnd alpha is more than 1 and less than or equal to 2, and the arc state formed by the positive tab 113 during welding can be more suitable for the calculation formula of the first welding section 1131 when the welding is tightened, so that the final length of the protrusion of the positive tab 113 is more in line with the actual situation, and all positive tabs subjected to final welding are more in line with the actual situationThe end surfaces of the tabs 113 are extremely flush.
Similarly, the second welding sections 1231 of the cathode electrode sheet groups 12 on the two sides have a certain radian and a length of lT is minus', at this time, "T is minus’＝β*lNegative plusAnd beta is more than 1 and less than or equal to 2, and by setting the correction constant, the arc state formed by the negative electrode tab 123 during welding is more suitable for the calculation formula of the second welding-together section 1231 when the second welding-together section is stretched straight, so that the final length of the extension of the negative electrode tab 123 is more in line with the actual situation, and the end faces of all the negative electrode tabs 123 after final welding are extremely high in levelness.
In some embodiments of the present invention, the positive tab 113 of the positive electrode tab group 11 and the negative tab 123 of the negative electrode tab group 12 both extend in the same direction and are located on the same side, and all the overlapped positive tabs 113 and all the overlapped negative tabs 123 are arranged at intervals in the horizontal direction. In these examples, all the tabs are located on the same side of the pole piece, which is also applicable to the design structure of the aforementioned tabs of the present application, and the ends of the positive tab 113 and the negative tab 123 can be flush; the horizontal spacing design can ensure that the positive electrode tab 113 and the negative electrode tab 123 do not interfere with each other during transportation and welding and are not short-circuited.
In other examples, as shown in fig. 1 and 3, positive tab 113 of positive tab stack 11 and negative tab 123 of negative tab stack 12 extend out toward different sides. In these examples, the positive tab 113 and the negative tab 123 are located on different sides of the cell body, and the same applies to the design structure of the tabs described above in the present application, and the ends of the positive tab 113 and the negative tab 123 are flush.
A method for molding the battery cell 100 according to the embodiment of the present invention is described below with reference to the drawings.
The method for forming the battery cell 100 according to the embodiment of the invention comprises a plurality of stacked pole piece groups 1, wherein each layer of the pole piece group 1 comprises a pole lug extending outwards, and the method comprises the following steps:
step S1: the positive pole piece groups 11 and the negative pole piece groups 12 with different polarities are alternately stacked in sequence, and the edges of the pole piece groups 1 with the same polarity are aligned.
Step S2: a layer of diaphragm 2 is additionally arranged between the adjacent anode plate group 11 and the adjacent cathode plate group 12.
Step S3: the pole lugs of the pole piece group 1 positioned in the middle layer horizontally extend out and have the shortest extension length, and the extension lengths of the pole lugs of the pole piece group 1 in the middle part to the pole lugs of the pole piece group 1 in the two side directions are sequentially increased progressively.
Step S4: the end surfaces formed by welding the positive electrode tabs 113 of all the positive electrode plate groups 11 are flush.
Step S5: the end surfaces formed by welding the negative electrode tabs 123 of all the negative electrode plate groups 12 are flush.
According to the method for forming the battery cell 100, the positive electrode plate groups 11 and the negative electrode plate groups 12 with different polarities are sequentially and alternately stacked, the edges of the electrode plate groups 1 with the same polarity are flush, the extending lengths of the electrode lugs are sequentially increased from the middle layer to the edge layer, and finally the electrode lugs with the same polarity are drawn together from two sides to the middle layer and welded to form the positive electrode lug 113 and the negative electrode lug 123 with flush end surfaces.
Optionally, before step S1, step S0 is further included: and arranging a layer of negative electrode plate group 12 at the bottommost layer, then stacking other electrode plate groups 1, leaving a layer of negative electrode plate group 12 at the topmost layer, arranging a positive electrode plate group 11 in the middle layer, stacking at least three layers of positive electrode plate groups 11, and forming the battery cell 100 with at least seven layers of electrode plate groups 1. The effect of arranging at least seven layers of pole piece groups 1 has been described previously and is not described here.
The following describes a specific structure of the battery cell 100 and a battery cell forming method in an embodiment of the present invention with reference to the drawings. The embodiments of the present invention may be all embodiments obtained by combining the foregoing technical solutions, and are not limited to the following specific embodiments, which fall within the scope of the present invention.
Example 1
A battery core 100, as shown in fig. 1, includes seven layers of pole piece groups 1, the multiple layers of pole piece groups 1 are stacked up and down, a separator 2 is arranged between adjacent pole piece groups 1 for connection, and the pole piece groups 1 of adjacent layers have different polarities. The positive pole piece groups 11 and the negative pole piece groups 12 are alternately arranged, the pole lugs of the same pole piece group 1 are vertically aligned, the two pole piece groups 1 positioned at the top side and the bottom side are the negative pole piece groups 12, the pole piece group 1 positioned at the middle part is the positive pole piece group 11, and the extending lengths of the positive pole lugs 113 of the two layers of positive pole piece groups 11 with the same interval distance from the central plane of the positive pole piece group 11 are the same; the negative electrode lugs 123 of the two layers of negative electrode pole piece groups 12 with the same distance from the central plane have the same extension length, and the end surfaces formed by the superposed lugs of the pole piece groups 1 with the same polarity are flush.
Example 2
A battery core 100 adopts 32 layers of negative electrode plate groups 12 and 31 layers of positive electrode plate groups 11, the thickness of a copper foil is 6 microns, the thickness of an aluminum foil is 12 microns, the thickness of a diaphragm 2 is 13 microns, a positive electrode lug 113 of the positive electrode plate group 11 positioned in the middle layer horizontally extends out, the length c of a first welding section 1131 is 5.1mm, the thickness of a positive electrode plate body 111 is 125 microns, the thickness of a negative electrode plate body 121 is 162 microns, alpha is 1.2, and beta is 1.3.
As shown in fig. 5, the voltage drop values in the cell detection 72H of 100 cells manufactured by the conventional tab forming method and the cell forming method of the present application are selected, and it is determined that, under the same voltage drop test condition for cells of the same system and the same size, the voltage drop of the cell manufactured by the cell forming method of the present application is reduced by about 0.000302V compared with the conventional method, the consistency level is significantly improved, and the pole difference is reduced from 0.0005V to 0.0003V.
In the description of the present invention, it is to be noted that, unless otherwise explicitly specified or limited, the term "connected" is to be interpreted broadly, e.g. as a fixed connection, a detachable connection, or an integral connection; either mechanically or electrically. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
Seven pole piece groups 1 are shown in fig. 1 for illustrative purposes, but it is obvious to those skilled in the art after reading the above technical solutions that the solution can be applied to more pole piece groups 1, and this also falls into the protection scope of the present invention.
Other configurations of the battery cell 100 and the battery cell forming method according to the embodiment of the present invention, such as the welding method of the battery cell 100, are known to those skilled in the art, and will not be described in detail herein.
In the description herein, references to the description of the terms "embodiment," "example," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
While embodiments of the invention have been shown and described, it will be understood by those of ordinary skill in the art that: various changes, modifications, substitutions and alterations can be made to the embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.
Claims (10)
1. The utility model provides an electric core, its characterized in that includes multilayer pole piece group, and multilayer pole piece group piles up the setting from top to bottom, and is adjacent be equipped with the diaphragm between the pole piece group and connect, adjacent layer the polarity of pole piece group is different, every layer the pole piece group all includes:
pole pieces;
the pole lug is connected with the pole piece and extends outwards; the extension length of the lugs is increased from the middle to the two sides, the lugs on the two sides are close to the middle lug and are overlapped, and the overlapped lugs are the same in polarity and the end faces formed by the lugs in the lug group are flush.
2. The battery cell of claim 1, wherein edges of the electrode sheet groups with the same polarity are aligned up and down, the electrode sheet groups include positive electrode sheet groups and negative electrode sheet groups with different polarities, each positive electrode sheet group includes a positive electrode sheet body, an aluminum foil and a positive electrode tab, and the aluminum foil is wrapped on the outer side of the positive electrode sheet body;
the negative electrode plate group comprises a negative electrode plate body, a copper foil and a negative electrode lug, and the copper foil is wrapped on the outer side of the negative electrode plate body;
the positive pole piece group and the negative pole piece group are alternately arranged, and the pole lugs of the same pole piece group are vertically aligned.
3. The battery cell of claim 2, wherein when the number of the same type of the pole piece group is an odd number of layers, the protruding length of the pole lug of the pole piece group located in the middle part is the shortest, and the protruding lengths of the pole lugs increase in sequence from the middle part to both sides;
when the number of the pole piece groups of the same kind is even, the extending lengths of the pole lugs of the two pole piece groups positioned in the middle are the same, and the extending lengths of the pole piece groups far away from the two sides of the middle pole piece group are sequentially increased.
4. The battery cell of claim 3, which comprises at least seven layers of pole piece groups, wherein the two layers of pole piece groups on the top side and the bottom side are both the negative pole piece groups, the one layer of pole piece group in the middle part is the positive pole piece group, and the extending lengths of the positive pole lugs of the two layers of positive pole piece groups which are spaced from the central plane of the positive pole piece group at the same distance are the same; the two layers of the negative electrode tab groups with the same distance from the central plane have the same extension length of the negative electrode tabs.
5. The battery cell according to claim 4, wherein the positive electrode sheet bodies on each layer have the same thickness and are denoted by z, the aluminum foil on each layer has the same thickness and is denoted by e, the negative electrode sheet bodies on each layer have the same thickness and is denoted by f, the separator on each layer has the same thickness and is denoted by g, the copper foil on each layer has the same thickness and is denoted by d, the tab comprises a welded section and a flush section, and the welded section has a cell body end close to the electrode sheet and a welded inner end connected with the flush section;
the length of the welding section of the positive plate group on the T-th layer positioned on the two sides is recorded as lT isThe height difference between the central plane of the positive electrode plate group of the middle layer and the central plane of the positive electrode plate group of the T-th layer at the two sides of the positive electrode plate group of the middle layer is recorded as hT is，lT isIs equal to the sum of the squares of c and hT isThe square sum of (1), wherein the welding section is in a stretched state; h isT is＝T*z+T*f+2*T*g-(T-1)*e；
The length of the welding section of the positive electrode plate group in the middle layer towards the T-th negative electrode plate groups on the two sides is recorded as lT is minusThe height difference between the central plane of the positive electrode plate group in the middle layer and the central plane of the negative electrode plate group in the T-th layer at the two sides from the central plane of the positive electrode plate group in the middle layer is recorded as hT is minus，lT is minusIs equal to the sum of the squares of c and hT is minusThe square sum of (1), wherein the welding section is in a stretched state; h isT is minus＝(T+0.5)*z+(T+0.5)*f+(2*T+1)*g-T*d。
6. The battery cell of claim 5, wherein the welded sections of the positive electrode plate groups on two sides have a certain radian and a length of lT is', at this time, "T is’＝α*lT is，1＜α≤2；
The welding sections of the cathode electrode plate groups positioned on the two sides have a certain radian and are l in lengthT is minus', at this time, "T is minus’＝β*lNegative plus，1＜β≤2。
7. The electric core according to any one of claims 2 to 6, wherein the positive tab of the positive tab group and the negative tab of the negative tab group both extend in the same direction and are located on the same side, and all the superimposed positive tabs and all the superimposed negative tabs are arranged at intervals in the horizontal direction.
8. The electrical core of any of claims 2 to 6, wherein the positive tab of the positive tab stack and the negative tab of the negative tab stack protrude towards different sides.
9. The battery core forming method is characterized by comprising a plurality of layers of pole piece groups stacked, wherein each layer of pole piece group comprises a pole lug extending outwards, and the method comprises the following steps:
sequentially and alternately stacking the anode plate groups and the cathode plate groups with different polarities, and aligning the edges of the electrode plate groups with the same polarity;
a layer of diaphragm is additionally arranged between the adjacent anode plate group and the adjacent cathode plate group;
the tabs of the pole piece group positioned in the middle layer horizontally extend out and have the shortest extension length, and the extension lengths of the tabs of the pole piece group from the middle pole piece group to the two side directions are sequentially increased;
welding positive lugs of all the positive plate groups to form end faces which are parallel and level;
and welding the negative electrode lugs of all the negative electrode plate groups to form end faces which are parallel and level.
10. The battery cell molding method according to claim 9,
and arranging one layer of negative electrode plate group at the bottommost layer, then stacking other electrode plate groups, and leaving one layer of negative electrode plate group at the topmost layer, wherein the positive electrode plate group is positioned in the middle layer and stacked with at least three layers of positive electrode plate groups, and the molded battery cell is provided with at least seven layers of electrode plate groups.
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| CN202011071311.9A CN112117497A (en) | 2020-10-09 | 2020-10-09 | Battery cell and battery cell forming method |
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