CN113571761B - Clamping and stacking type electrode assembly and manufacturing method thereof - Google Patents
Clamping and stacking type electrode assembly and manufacturing method thereof Download PDFInfo
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- CN113571761B CN113571761B CN202111125811.0A CN202111125811A CN113571761B CN 113571761 B CN113571761 B CN 113571761B CN 202111125811 A CN202111125811 A CN 202111125811A CN 113571761 B CN113571761 B CN 113571761B
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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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- 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
- H01M10/0583—Construction or manufacture of accumulators with folded construction elements except wound ones, i.e. folded positive or negative electrodes or separators, e.g. with "Z"-shaped electrodes or separators
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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
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- 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
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Abstract
The invention discloses a clamping and stacking type electrode assembly and a manufacturing method thereof, which are used for solving the technical problem that positive and negative pole pieces in the existing stacking type electrode assembly are easy to displace and are contacted with each other to cause short circuit of a battery. After being folded, the first active pole piece forms a first folding area in the middle of the first active pole piece, two adjacent sides of the first folding area are respectively provided with a first active material coating area, one side of the first active material coating area is provided with a first pole lug empty foil area, and a first pole lug is formed on the first pole lug empty foil area; after the second active pole piece is folded, second tab empty foil areas are arranged on two adjacent sides of the crease line of the second active pole piece, a second active material coating area is arranged on one side of each second tab empty foil area, a second tab is formed on each second tab empty foil area, and the two second tabs are connected with each other; the isolating film is folded to form a zigzag structure which is repeatedly extended, and the first active pole piece and the second active pole piece are respectively stacked on two opposite sides of the isolating film.
Description
Technical Field
The invention relates to the technical field of battery design, in particular to a clamping and stacking type electrode assembly and a manufacturing method thereof.
Background
In recent years, industries related to new energy resources develop rapidly, and the lithium ion battery technology is widely applied to the subdivided fields of electric automobiles, base station energy storage, electric tools and the like due to the advantages of the lithium ion battery technology, wherein the specific energy density is an important index for evaluating the lithium ion battery.
The existing technical route for improving the specific energy density of the battery cell can be roughly divided into two categories: the specific energy per unit of an active chemical system is improved, and the method is difficult to be quickly applied due to the existence of a larger technical bottleneck; the other is to reduce the proportion of inactive substances, including the huge cell size, the increase of the active substance load capacity, the thinning of the current collector substrate/packaging material, the improvement of the available space utilization rate and other means, and the switching from the winding process to the lamination process is the most common and simple route. In the traditional lamination process, lamination is generally carried out in a mode that one layer of positive plate, one layer of diaphragm and one layer of negative plate are circularly stacked layer by layer, and in the mode, the positive plate or the negative plate is easy to shift in the stacking process, so that the positive plate and the negative plate are contacted with each other, and the problem of short circuit of the battery is caused.
Therefore, it is an important subject of research by those skilled in the art to find a sandwich electrode assembly and a method for manufacturing the same, which can solve the above-mentioned problems.
Disclosure of Invention
The embodiment of the invention discloses a clamping and stacking type electrode assembly and a manufacturing method thereof, which are used for solving the technical problem that the positive and negative pole pieces are contacted with each other to cause the short circuit of a battery because the pole pieces in the existing stacking type electrode assembly are easy to displace.
The embodiment of the invention provides a sandwich type electrode assembly, which comprises an isolating membrane, at least one first active pole piece and at least one second active pole piece, wherein the isolating membrane is arranged between the first active pole piece and the second active pole piece;
the first active pole piece is provided with a first active material coating area and a first pole lug empty foil area; after the first active pole piece is folded along the central axis of the first active pole piece, a first folding area is formed in the middle of the first active pole piece, the two adjacent sides of the first folding area are respectively provided with a first active substance coating area, one side, far away from the first folding area, of the first active substance coating area is provided with a first pole lug empty foil area, and a first pole lug exposed out of the first active pole piece is formed on the first pole lug empty foil area;
a second active material coating area and a second pole ear empty foil area are arranged on the second active pole piece; after the second active pole piece is folded along the central axis, second pole ear empty foil areas are arranged on two adjacent sides of the crease of the second active pole piece, a second active material coating area is arranged on one side, away from the crease, of each second pole ear empty foil area, second pole ears are formed on the second pole ear empty foil areas, and the second pole ears on the two second pole ear empty foil areas are connected with each other;
the isolating membrane is folded for a plurality of times to form a repeatedly extending zigzag structure, the first active pole piece and the second active pole piece are respectively stacked on two opposite sides of the isolating membrane, a V-shaped notch formed by folding the first active pole piece is arranged towards a folding corner on one side of the isolating membrane, a V-shaped notch formed by folding the second active pole piece is arranged towards a folding corner on the other side of the isolating membrane, and the repeatedly extending zigzag structure is repeatedly extended in a mode of first active pole piece-isolating membrane-second active pole piece-isolating membrane-first active pole piece;
the isolating film and the folding position of the first lug opposite to each other are provided with a hole for the first lug to penetrate out.
Optionally, a first functional coating region is further disposed on the first active tab, the first functional coating region is located between the first tab foil region and the first active material coating region, and the first functional coating region is coated with an inorganic non-metallic material or a high molecular material.
Optionally, a second functional coating region is further disposed on the second active tab, the second functional coating region being located between the second tab empty foil region and the second active material coating region and on a side of the second active material coating region away from the second tab empty foil region, the second functional coating region being coated with an inorganic non-metallic material or a polymeric material.
Optionally, the width of the opening is greater than the width of the first tab;
the width of the opening is less than 25% of the length of the fold of the isolating film where the opening is located, and the width of the first tab accounts for 50% -95% of the width of the opening.
Optionally, the width of the first active material coated region is greater than the width of the first tab open foil region, which is greater than the width of the first folded region;
the width of the second active material coated region is greater than the width of the second tab empty foil region.
Optionally, the second tabs are all exposed from the isolation film, and the first tabs and the second tabs are located on the same side of the isolation film.
Optionally, a corner margin of the isolation film adjacent to the first folding area is coated on the first folding area, and an insulating coating is coated on the first folding area.
The embodiment of the invention provides a manufacturing method of a clamping and stacking type electrode assembly, which comprises the following steps:
folding the first active pole piece along the central axis thereof to form a first folding area in the middle, coating active substances on two adjacent sides of the first folding area to form a first active substance coating area on two adjacent sides of the first folding area, leaving an inactive substance coating area on one side of the first active substance coating area far away from the first folding area as a first pole tab empty foil area, and carrying out die cutting treatment on the first pole tab empty foil area to form a first pole tab exposed out of the first active pole piece;
folding the second active pole piece along the central axis thereof to form a crease in the middle, leaving non-active substance coating areas on two adjacent sides of the crease as second pole tab empty foil areas, coating active substances on one side of the second pole tab empty foil areas far away from the crease, forming second active substance coating areas on one side of the second pole tab empty foil areas far away from the crease, and carrying out die cutting treatment on the second pole tab empty foil areas to form second pole tabs, wherein the second pole tabs on the two second pole tab empty foil areas are connected with each other;
folding the isolating film for a plurality of times to form a repeatedly extending zigzag structure, and arranging an opening at the folding position of the isolating film opposite to the first tab, wherein the opening is used for exposing the first tab out of the isolating film; and laminating the first active pole piece and the second active pole piece from the two opposite sides of the isolating membrane and repeatedly extending the first active pole piece, the isolating membrane, the second active pole piece, the isolating membrane and the first active pole piece in a mode of first active pole piece, second active pole piece, isolating membrane and first active pole piece to form the laminated electrode assembly.
Optionally, the method further comprises: applying a functional coating between the first tab open foil area and the first active material coated area such that a first functional coated area is formed between the first tab open foil area and the first active material coated area;
and applying a functional coating between the second tab empty foil area and the second active material coated area and applying a functional coating on a side of the second active material coated area remote from the second tab empty foil area, such that a second functional coated area is formed between the second tab empty foil area and the second active material coated area and on a side of the second active material coated area remote from the second tab empty foil area.
Optionally, the method further comprises: and after coating an insulating coating on the first folding area of the first active pole piece, carrying out hot pressing operation on the folded electrode assembly, so that the corner margin of the isolating film close to the first folding area is coated on the first folding area.
According to the technical scheme, the embodiment of the invention has the following advantages:
in the sandwich electrode assembly in this embodiment, the first active electrode sheet and the second active electrode sheet are folded, and the first active electrode sheet and the second active electrode sheet are subjected to differential coating and die cutting, so that the geometric positions of the tabs formed by the first active electrode sheet and the second active electrode sheet are different, and the first active electrode sheet and the second active electrode sheet are respectively stacked on the two opposite sides of the isolation film, so that the first active electrode sheet and the second active electrode sheet are in an alternate engagement structure, and the active electrode sheet and the isolation film are more tightly attached, so that the active electrode sheets are not easy to shift, and the technical problem that each layer of active electrode sheet is easy to shift and causes short circuit of the battery is effectively solved.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without inventive exercise.
Fig. 1 is a schematic structural diagram of a first active electrode sheet in a sandwich electrode assembly provided in an embodiment of the present invention when die cutting is not performed;
fig. 2 is a schematic structural diagram of a first active electrode sheet in a sandwich electrode assembly after die cutting according to an embodiment of the present invention;
fig. 3 is a schematic structural diagram of a second active electrode sheet in a sandwich electrode assembly provided in an embodiment of the present invention when die cutting is not performed;
fig. 4 is a schematic structural diagram of a second active electrode sheet in a sandwich electrode assembly after die cutting according to an embodiment of the present invention;
fig. 5 is a schematic view of a first active electrode plate, a second active electrode plate, and an isolation film of a sandwich electrode assembly according to an embodiment of the present invention during lamination;
fig. 6 is a schematic structural view of a sandwich type electrode assembly provided in an embodiment of the present invention;
fig. 7 is a schematic cross-sectional view of a sandwich electrode assembly according to an embodiment of the present invention;
FIG. 8 is a diagram illustrating a positional relationship between a first active electrode and a second active electrode in a lamination process according to the prior art;
fig. 9 is a diagram illustrating a positional relationship between a first active electrode piece and a second active electrode piece in a sandwich electrode assembly according to an embodiment of the present invention;
fig. 10 is a schematic flow chart illustrating a method of fabricating a sandwich electrode assembly according to an embodiment of the present invention;
illustration of the drawings: a first active pole piece 1; a first active material coated region 101; a first fold region 102; a corner position 102W of the first active pole piece; a first functional coating region 103; a first tab foil area 104; a first tab 1041; the thick edge 105 of the first active pole piece; the thin edge 106 of the first active pole piece; a second active pole piece 2; a second active material coated region 201; a second functional coating region 202; a second pole ear cavity foil region 203; a second pole ear 2031; a thick edge 204 of the second active pole piece; a thin edge 205 of the second active pole piece; a separator 3; corner redundancy 301 of the isolation film; an opening 302.
Detailed Description
The embodiment of the invention discloses a clamping and stacking type electrode assembly and a manufacturing method thereof, which are used for solving the technical problem that the positive and negative pole pieces are contacted with each other to cause the short circuit of a battery because the pole pieces in the existing stacking type electrode assembly are easy to displace.
In order that those skilled in the art will better understand the disclosure, the invention will be described in further detail with reference to the accompanying drawings and specific embodiments. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. 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 invention.
Example one
Referring to fig. 1 to 9, a stacked electrode assembly according to an embodiment of the present invention includes:
the separator 3 and at least one first active pole piece 1 and one second active pole piece 2, specifically, the number of the first active pole pieces 1 may be one or more, and the number of the second active pole pieces 2 may be one or more;
a first active material coating area 101 and a first tab empty foil area 104 are arranged on the first active pole piece 1; the middle of the first active pole piece 1 is folded along the central axis thereof to form a first folding area 102, the two adjacent sides of the first folding area 102 are both provided with the first active material coating area 101, one side of the first active material coating area 101, which is far away from the first folding area 102, is provided with the first tab empty foil area 104, and the first tab 1041 exposed out of the first active pole piece 1 is formed on the first tab empty foil area 104;
specifically, as shown in fig. 1 and fig. 2, the first folding area 102 is located on a central axis of the first active electrode sheet 1, the left and right sides of the first folding area 102 are respectively provided with a first active material coating area 101, one side of the first active material coating area 101, which is far away from the first folding area 102, is provided with a first tab empty foil area 104, the first tab empty foil area 104 is not coated with an active material, and an operator performs die cutting on the first tab empty foil area 104 by a die cutting method to obtain a first tab 1041, and as shown in fig. 2, the first tab 1041 is located on the left and right sides of the first active electrode sheet 1 respectively.
A second active material coating area 201 and a second pole ear empty foil area 203 are arranged on the second active pole piece 2; after the second active electrode sheet 2 is folded along the central axis thereof, second tab empty foil areas 203 are respectively arranged on two adjacent sides of the fold, a second active material coating area 201 is arranged on one side, away from the fold, of the second tab empty foil area 203, second electrode lugs 2031 are formed on the second tab empty foil areas 203, and the second electrode lugs 2031 on the two second tab empty foil areas 203 are connected with each other;
specifically, as shown in fig. 3 and 4, the fold is substantially obtained by folding along the second tab empty foil area 203, the second tab empty foil area 203 is located at the middle position of the second active electrode sheet 2, the second active material coating areas 201 are arranged at the left and right sides of the second tab empty foil area 203, and an operator performs die cutting on the second tab empty foil area 203 by means of die cutting to obtain the second tab 2031, as shown in fig. 2, the second tabs 2031 on the two second tab empty foil areas 203 are connected with each other into a whole and are located between the two second active material coating areas 201;
as shown in fig. 5 and 6, the isolation film 3 forms a zigzag structure extending repeatedly after being folded for a plurality of times, the first active electrode sheet 1 and the second active electrode sheet 2 are stacked on two opposite sides of the isolation film 3 respectively, the V-shaped notch formed by folding the first active electrode sheet 1 is arranged toward the folding corner on one side of the isolation film 3, the V-shaped notch formed by folding the second active electrode sheet 2 is arranged toward the folding corner on the other side of the isolation film 3, and the zigzag structure extends repeatedly according to the manner of the first active electrode sheet 1-the isolation film 3-the second active electrode sheet 2-the isolation film 3-the first active electrode sheet 1.
In order to expose the first tab 1041 to the isolation film 3, please refer to fig. 7, an opening 302 is disposed at a folding position of the isolation film 3 opposite to the first tab 1041, and the first tab 1041 can be exposed to the isolation film 3 after passing through the opening 302. Specifically, the width of the opening hole 302 is greater than the width of the first tab 1041, the width of the opening hole 302 is less than 25% of the length of the fold of the separator 3 where the opening hole 302 is located, and the width of the first tab 1041 accounts for 50% to 95% of the width of the opening hole 302.
It should be noted that the advantage of designing the width of the opening 302 to exceed the width of the first tab 1041 is that:
(1) the root department that can make first utmost point ear 1041 lacks the accumulation of barrier film 3 for barrier film 3 is less than active pole piece main part thickness at the accumulated thickness in first utmost point ear 1041 root department, and then makes first utmost point ear 1041 root degree of freedom promote, is difficult for being torn.
(2) The isolating membrane 3 is provided with the opening 302, so that stress release in the charging and discharging process is facilitated, and the isolating membrane 3 is prevented from being wrinkled to influence an interface.
(3) The isolating membrane 3 sets up trompil 302 is favorable to helping the active pole piece can be more even, soaks fast, and the trompil 302 of isolating membrane 3 has simultaneously increased the gas vent in other words, prevents that the gaseous continuation of active pole piece from collecting and causing the interface bad.
Further, the first active electrode tab 1 may be a positive electrode tab or a negative electrode tab, the second active electrode tab 2 may be a positive electrode tab or a negative electrode tab, when the first active electrode tab 1 is a positive electrode tab, the second active electrode tab 2 is a negative electrode tab, the first active material coating area 101 is coated with a positive active material, and the second active material coating area 201 is coated with a negative active material. On the contrary, when the first active electrode sheet 1 is a negative electrode sheet and the second active electrode sheet 2 is a positive electrode sheet, the first active material coating region 101 is coated with a negative electrode active material, and the second active material coating region 201 is coated with a positive electrode active material.
In the sandwich electrode assembly in this embodiment, the first active electrode sheet 1 and the second active electrode sheet 2 are folded, and the first active electrode sheet 1 and the second active electrode sheet 2 are subjected to differential coating and die cutting, so that the geometric positions of the tabs formed by the first active electrode sheet 1 and the second active electrode sheet 2 are different, and the first active electrode sheet 1 and the second active electrode sheet 2 are respectively stacked on the two opposite sides of the isolation film 3, so that the first active electrode sheet 1 and the second active electrode sheet 2 are in an alternate engagement structure, the active electrode sheet and the isolation film 3 are more tightly attached, the active electrode sheet is less likely to shift, the edge loss probability (powder falling, burr and wire drawing) of the active electrode sheet is greatly reduced, thereby improving the self-discharge and safety performance of the battery cell, and more importantly, the respective thickness gradients of the first active electrode sheet 1 and the second active electrode sheet 2 are mutually offset, the thickness gradient of the finally formed electrode assembly is greatly reduced, and the technical problem that the thickness of the electrode assembly is seriously uneven is effectively solved, so that the situation that the later-stage serious deformation of the electrode assembly is caused by serious unevenness of the thickness is avoided. Meanwhile, the first tab 1041 and the second tab 2031 can still be led out from one side of the isolating film 3, so that the advantage of high space utilization rate (namely the advantage of high energy density) is ensured. In addition, the clamping and stacking type electrode assembly can stack two or more layers of active pole pieces at one time, the stacking efficiency of the whole process can be effectively improved, meanwhile, the number of layers of the lugs can be controlled, the assembly space utilization rate is effectively improved, the energy density of the battery cell is further improved, and the advantages are more obvious particularly in large-size and multi-layer battery cells.
Furthermore, a first functional coating region 103 is also provided on the first active electrode sheet 1, and the first functional coating region 103 is located between the first tab empty foil region 104 and the first active material coating region 101.
A second functional coating region 202 is also provided on the second active pole piece 2, the second functional coating region 202 being located between the second tab void foil region 203 and the second active material coated region 201 and on the side of the second active material coated region remote from the second tab void foil region 203.
It should be noted that the first functional coating region 103 and the second functional coating region 202 are both coated with a coating having an insulation protection or toughness enhancing effect, and are typically inorganic non-metallic materials or polymeric materials.
Specifically, as can be seen from fig. 1 to 4, the width of the first active material coated region 101 is greater than the width of the first tab empty foil region 104, and the width of the first tab empty foil region 104 is greater than the width of the first folding region 102.
The width of the second active material coated region 201 is greater than the width of the second tab empty foil region 203.
It should be noted that the first folding area 102 in the present embodiment can be simply understood as a fold, wherein the width of the first folding area 102 ranges from 0 mm to 5 mm. In addition, the width of the first functional coating region 103 and the second functional coating region 202 in this embodiment is also relatively small, and the width range of both is 0 to 5 mm.
Further, the first tab 1041 and the second tab 2031 are both exposed out of the isolation film 3, and the first tab 1041 and the second tab 2031 are located on the same side of the isolation film 3.
As can be seen from fig. 1 to 4, the first tab 1041 is perpendicular to the first folding region 102 (fold) at an angle of 90 °. The second pole tab 2031 is at a 90 angle to the fold.
Further, a corner margin 301 of the isolation film 3 adjacent to the first folding area 102 is wrapped on the first folding area 102, and an insulating coating is coated on the first folding area 102.
It should be noted that, as shown in fig. 7, the first active electrode sheet 1 and the second active electrode sheet 2 are respectively attached to and correspond to the upper surface and the lower surface of the isolation film 3 one by one, although the corner position 102W (the first folding region) of the first active electrode sheet 1 is exposed to the outermost layer, the corner position 301 (the folding position) of the isolation film 3 may be set near the lamination layer, and the corner position 102W of the first active electrode sheet 1 may be covered by the corner position 301 after the electrode assembly is subjected to the hot pressing and shaping, so that the safety performance of the electrode assembly in the edge region may not be sacrificed.
Further, the existing coating technology determines that the first active pole piece 1 and the second active pole piece 2 have thickness gradient phenomenon in the production process of the previous working procedure.
Specifically, the first active electrode sheet 1 and the second active electrode sheet 2 in fig. 8 are stacked by using an existing lamination process, and the first active electrode sheet 1 and the second active electrode sheet 2 are applied by the same die cutting and non-differential coating process, when the first active electrode sheet 1 and the second active electrode sheet 2 are coated with active materials, the thickness of the active paste on the side close to the tab is thin, and the thickness of the active paste on the side far from the tab is thick, as shown in fig. 8, the left side of the first active electrode sheet 1 is the thick side thereof, the right side thereof is the thin side thereof, the left side of the second active electrode sheet 2 is the thick side thereof, the right side thereof is the thin side thereof, the thickness of the thick side and the thickness of the thin side of the first active electrode sheet 1 are d1 and d2, respectively, and the thickness of the thick side and the thickness of the thin side of the second active electrode sheet 2 are d3 and d4, respectively. Taking an electrode assembly with n layers of first active pole pieces 1 as an example, the first active pole piece 1 and the second active pole piece 2 are overlapped with each other in a thick edge area at one side of a pole group and in a thin edge area at the other side of the electrode assembly by using a traditional lamination method, and the final maximum value of the thickness gradient of the electrode assembly is T = n (d 1-d 2) + (n +/-1) (d3-d4) and is approximately T1= n (d1+ d3-d2-d 4);
as shown in fig. 9, when the structure of the electrode assembly in this embodiment is changed, the first active electrode sheet 1 and the second active electrode sheet 2 are coated differently and die-cut differently, after the first active pole piece 1 and the active pole piece 2 are coated with active substances, the thick edge is arranged at the left side of the first active pole piece 1, the thin edge is arranged at the right side of the first active pole piece 1, the thick edge is arranged at the middle part of the second active pole piece, the left side and the right side are the thin edges, because the thick and thin areas of the first active pole piece 1 and the second active pole piece 2 are mutually offset due to the crossed overlapping of the areas to a great extent, the maximum thickness gradient can be approximated as T2= n (d1+ d4-d2-d 3), the difference in thickness gradient from the two lamination methods can be approximated as T = T1-T2=2n (d3-d4), where n is directly related to the number of layers of the active pole piece, and (d3-d4) is highly related to the size of the active pole piece and the amount of dressing per unit area.
Therefore, when the cell energy density is increased by methods of increasing the amount of the coating material per unit area, increasing the number of layers of the active pole pieces, increasing the size of the active pole pieces and the like, which are frequently adopted at present, the electrode assembly adopting the conventional lamination process has obvious disadvantages compared with the electrode assembly in the present example. The electrode assembly of the embodiment can well solve the technical problem that the existing electrode assembly is easy to have serious uneven accumulated thickness, so that the situation that the electrode assembly is seriously deformed in the later period due to the serious uneven thickness is avoided.
Compared with the T1 value of the traditional lamination process which is easily greater than 100um, the T2 value of the pole group manufactured by the method disclosed in the example is greatly reduced, and the electrode assembly does not have poor regional heat laminating effect due to thickness gradient in the hot pressing process after lamination; meanwhile, the inherent volume effect of the electrode assembly in the later charging and discharging process is considered, the thickness gradient of the electrode assembly in the initial stage is reduced as much as possible, the stress is distributed on the electrode assembly evenly, and the rapid deterioration of the electrochemical performance and the safety performance caused by the phenomena of serious fold and powder falling of the electrode assembly due to the local stress concentration is prevented.
Example two
Referring to fig. 1 to 10, the present embodiment provides a method for manufacturing a stacked electrode assembly, which is used to manufacture the stacked electrode assembly according to the first embodiment, and mainly includes the following steps:
step S1, folding the first active electrode sheet 1 along its central axis to form a first folded area 102 in the middle, coating active materials on two adjacent sides of the first folded area 102 to form a first active material coated area 101 on two adjacent sides of the first folded area 102, leaving an inactive material coated area as a first tab empty foil area 104 on one side of the first active material coated area 101 away from the first folded area 102, and performing die cutting processing on the first tab empty foil area 104 to form a first tab 1041 exposed out of the first active electrode sheet 1;
step S2, folding the second active electrode sheet 2 along its central axis to form a fold in the middle, leaving an inactive material coated area on two adjacent sides of the fold as a second tab 2031 empty foil area, coating an active material on the side of the second tab 2031 empty foil area away from the fold to form a second active material coated area 201 on the side of the second tab empty foil area 203 away from the fold, performing a die cutting process on the second tab empty foil area 203 to form a second tab 2031, and connecting the second tabs 2031 on the two second tab empty foil areas 203;
step S3, folding the isolation film 3 for several times to form a repeatedly extending zigzag structure, and opening holes 302 for exposing the first tab 1041 to the isolation film 3 are formed at the folding positions of the isolation film 3 opposite to the first tab 1041;
and (2) enabling a V-shaped notch formed by folding the first active pole piece 1 to face a folding corner on one side of the isolating membrane 3, enabling a V-shaped notch formed by folding the second active pole piece 2 to face a folding corner on the other side of the isolating membrane 3, laminating the first active pole piece 1 and the second active pole piece 2 from two opposite sides of the isolating membrane 3, and repeatedly extending according to the mode of the first active pole piece 1-the isolating membrane 3-the second active pole piece 2-the isolating membrane 3-the first active pole piece 1 to form the laminated electrode assembly.
Further, the method for manufacturing a sandwich electrode assembly in this embodiment further includes: applying a functional coating between the first tab foil-free area 104 and the first active material coated area 101 such that a first functional coated area 103 is formed between the first tab foil-free area 104 and the first active material coated area 101;
a functional coating is applied between the second tab void foil area 203 and the second active material coated area 201 and on the side of the second active material coated area remote from the second tab void foil area 203, such that a second functional coated area 202 is formed between the second tab void foil area 203 and the second active material coated area 201 and on the side of the second active material coated area remote from the second tab void foil area 203.
Further, the method for manufacturing a sandwich electrode assembly in this embodiment further includes: after the insulating coating is coated on the first folding region 102 of the first active electrode tab 1, the folded electrode assembly is hot-pressed, so that the corner margin 301 of the isolation film 3 adjacent to the first folding region 102 is covered on the first folding region 102.
Note that, the first active electrode sheet 1 and the second active electrode sheet 2 in the sandwich electrode assembly can be changed from the loose state to the compact state by the hot pressing operation.
The sandwich electrode assembly manufactured by the manufacturing method in the embodiment can enable the first active pole piece 1 and the second active pole piece 2 to be in an alternate occlusion structure, the pole pieces are more tightly attached to the isolating membrane 3, so that the pole pieces are more difficult to shift, the loss probability (powder falling, burr and wire drawing) of the edges of the active pole pieces is greatly reduced, the self-discharge performance, the safety performance and the like of the battery cell are improved, more importantly, the original thickness gradients of the first active pole piece 1 and the second active pole piece 2 are mutually offset, the thickness gradient of the finally formed electrode assembly is greatly reduced, the technical problem that the thickness of the electrode assembly is seriously uneven is effectively solved, and the situation that the later-stage serious deformation of the electrode assembly is caused by serious uneven thickness is avoided. Meanwhile, the first tab 1041 and the second tab 2031 can still be led out from one side of the isolating film 3, so that the advantage of high space utilization rate (namely the advantage of high energy density) is ensured. In addition, the laminated electrode assembly manufactured by the method can stack two or more layers of active pole pieces at one time, the lamination efficiency can be effectively improved, meanwhile, the manufacturing method can effectively improve the assembly space utilization rate by controlling the number of layers of the pole lugs, further improve the energy density of the battery cell, and has more obvious advantages particularly in the battery cell with large size and multiple layers.
While the present invention has been particularly shown and described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention.
Claims (8)
1. A sandwich electrode assembly comprising a separator and at least a first active electrode sheet and a second active electrode sheet;
the first active pole piece is provided with a first active material coating area and a first pole lug empty foil area; after the first active pole piece is folded along the central axis of the first active pole piece, a first folding area is formed in the middle of the first active pole piece, the two adjacent sides of the first folding area are respectively provided with a first active substance coating area, one side, far away from the first folding area, of the first active substance coating area is provided with a first pole lug empty foil area, and a first pole lug exposed out of the first active pole piece is formed on the first pole lug empty foil area;
a second active material coating area and a second pole ear empty foil area are arranged on the second active pole piece; after the second active pole piece is folded along the central axis, second pole ear empty foil areas are arranged on two adjacent sides of the crease of the second active pole piece, a second active material coating area is arranged on one side, away from the crease, of each second pole ear empty foil area, second pole ears are formed on the second pole ear empty foil areas, and the second pole ears on the two second pole ear empty foil areas are connected with each other;
the isolating membrane is folded for a plurality of times to form a repeatedly extending zigzag structure, the first active pole piece and the second active pole piece are respectively stacked on two opposite sides of the isolating membrane, a V-shaped notch formed by folding the first active pole piece is arranged towards a folding corner on one side of the isolating membrane, a V-shaped notch formed by folding the second active pole piece is arranged towards a folding corner on the other side of the isolating membrane, and the repeatedly extending zigzag structure is repeatedly extended in a mode of first active pole piece-isolating membrane-second active pole piece-isolating membrane-first active pole piece;
the folding part of the isolating film, which is opposite to the first tab, is provided with an opening through which the first tab penetrates;
the first folding region of the first active pole piece is exposed on the outermost layer, the isolating membrane is close to the corner surplus position arranged in the first folding region, the insulating coating is coated on the first folding region, and after hot pressing, the corner surplus position is coated on the first folding region to form the clamping type electrode assembly.
2. The sandwich electrode assembly of claim 1, wherein a first functional coating region is further disposed on the first active electrode sheet between the first tab foil region and the first active material coating region, the first functional coating region being coated with an inorganic non-metallic material or a polymeric material.
3. The sandwich electrode assembly of claim 1, wherein a second functional coating region is further disposed on the second active electrode sheet between the second tab void foil region and the second active material coating region and on a side of the second active material coating region remote from the second tab void foil region, the second functional coating region being coated with an inorganic non-metallic material or a polymeric material.
4. The sandwich electrode assembly of claim 1 wherein the opening has a width greater than a width of the first tab;
the width of the opening is less than 25% of the length of the fold of the isolating film where the opening is located, and the width of the first tab accounts for 50% -95% of the width of the opening.
5. The sandwich electrode assembly of claim 1, wherein the first active material coated region has a width greater than a width of the first tab open foil region, the first tab open foil region having a width greater than a width of the first folded region;
the width of the second active material coated region is greater than the width of the second tab empty foil region.
6. The sandwich electrode assembly of claim 1, wherein the second tabs are each exposed to the separator film, and the first tab is on the same side of the separator film as the second tab.
7. A method for manufacturing a sandwich type electrode assembly is characterized by comprising the following steps:
folding the first active pole piece along the central axis thereof to form a first folding area in the middle, coating active substances on two adjacent sides of the first folding area to form a first active substance coating area on two adjacent sides of the first folding area, leaving an inactive substance coating area on one side of the first active substance coating area far away from the first folding area as a first pole tab empty foil area, and carrying out die cutting treatment on the first pole tab empty foil area to form a first pole tab exposed out of the first active pole piece;
folding the second active pole piece along the central axis thereof to form a crease in the middle, leaving non-active substance coating areas on two adjacent sides of the crease as second pole tab empty foil areas, coating active substances on one side of the second pole tab empty foil areas far away from the crease, forming second active substance coating areas on one side of the second pole tab empty foil areas far away from the crease, and carrying out die cutting treatment on the second pole tab empty foil areas to form second pole tabs, wherein the second pole tabs on the two second pole tab empty foil areas are connected with each other;
folding the isolating film for a plurality of times to form a repeatedly extending zigzag structure, and arranging an opening at the folding position of the isolating film opposite to the first tab, wherein the opening is used for exposing the first tab out of the isolating film; enabling a V-shaped notch formed by folding the first active pole piece to face a folding corner on one side of the isolating membrane, enabling a V-shaped notch formed by folding the second active pole piece to face a folding corner on the other side of the isolating membrane, laminating the first active pole piece and the second active pole piece from two opposite sides of the isolating membrane, and repeatedly extending in a mode of first active pole piece-isolating membrane-second active pole piece-isolating membrane-first active pole piece;
after lamination, the first folding area of the first active pole piece is exposed on the outermost layer, the isolation film forms a corner surplus position at the position close to the first folding area, and after the first folding area of the first active pole piece is coated with an insulating coating, hot pressing operation is carried out on the obtained assembly, so that the corner surplus position is covered on the first folding area to form the sandwich type electrode assembly.
8. The method of making a sandwich electrode assembly of claim 7 further comprising:
applying a functional coating between the first tab open foil area and the first active material coated area such that a first functional coated area is formed between the first tab open foil area and the first active material coated area;
and applying a functional coating between the second tab empty foil area and the second active material coated area and applying a functional coating on a side of the second active material coated area remote from the second tab empty foil area, such that a second functional coated area is formed between the second tab empty foil area and the second active material coated area and on a side of the second active material coated area remote from the second tab empty foil area.
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| CN114335831B (en) * | 2021-12-28 | 2024-03-01 | 远景动力技术(江苏)有限公司 | Laminated battery core and preparation method thereof |
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