Battery cell, and production device and preparation method therefor

Abstract

The present application discloses a battery cell, and a production device and preparation method therefor. The battery cell comprises cathode electrode plates and anode electrode plates stacked alternately with one another. In two adjacent electrode plates, along a direction parallel to an electrode plate surface and perpendicular to a first side edge, the first side edge of the anode electrode plate extends beyond the cathode electrode plate by a distance that is limited to within 0.6 mm, and along a direction parallel to the electrode plate surface and perpendicular to a second side edge, the second side edge of the anode electrode plate extends beyond the cathode electrode plate by a distance that is limited to within 0.6 mm. In this way, the space occupied by AC-Overhang structures in the two directions of the first side edge and the second side edge of the electrode plate is at least reduced, thereby improving the energy density of the battery cell. Moreover, during production, rapid alignment of anode electrode plates and cathode electrode plates is realized by means of a clamp, greatly decreasing the accuracy requirements for moving and placing the electrode plates, which not only increases battery cell production efficiency, but can also reduce production costs in terms of equipment and process difficulty.

Description

Battery cells, their production equipment and preparation methods Technical Field

[0001] This invention relates to the field of battery technology, and in particular to a battery cell, its manufacturing equipment, and its preparation method. Background Technology

[0002] The stacked cell process involves cutting electrodes and separators to specific sizes and shapes, and then stacking them in a specific order. During stacking, if the edge of the cathode electrode extends beyond the cathode electrode, lithium plating can occur on the anode during charging, forming dendrites. These dendrites can puncture the separator, causing an internal short circuit in the lithium battery. Therefore, it is necessary to ensure that the edges of the anode and cathode electrodes are aligned, or that the edge of the anode electrode extends beyond the cathode electrode, to avoid lithium plating on the anode electrode during charging. In actual production, when stacking electrodes, high-precision robotic arms are used to grasp the electrodes and place them on top of each other. However, since the precision of the robotic arms is difficult to meet the requirements for aligning the edges of the anode and cathode electrodes, existing stacked cells usually adopt an AC-Overhang structure. The AC-Overhang is the part of the anode electrode whose length and / or width exceeds that of the cathode electrode. The AC-Overhang structure makes the length and / or width of the anode electrode greater than that of the cathode electrode, ensuring that the anode electrode has enough space to absorb lithium ions and reserving a certain fault tolerance space for the alignment of the anode and cathode electrodes, thereby reducing the requirements for the alignment precision of the anode and cathode electrodes.

[0003] However, the large AC-Overhang size of this structure reduces the energy density of the battery cell. At the same time, the alignment of the electrode sheets during stacking still has high process requirements. Summary of the Invention

[0004] The present invention aims to provide a battery cell, its production equipment and preparation method, which can solve the technical problem of low energy density of battery cells in the prior art.

[0005] According to a first aspect of this application, this application discloses a battery cell, comprising:

[0006] Multiple electrodes are stacked together. Each electrode has at least a first side, a second side, and a third side. There is a first included angle between the first side and the second side of each electrode. The electrode is an anode electrode or a cathode electrode. The multiple electrodes include at least one anode electrode and at least one cathode electrode. The anode electrode and the cathode electrode are stacked alternately.

[0007] Each electrode is provided with a tab, which is located on the third side.

[0008] In the two adjacent electrode pieces, the size of the first side of the anode electrode piece exceeding the cathode electrode piece in the direction parallel to the surface of the electrode piece and perpendicular to the first side is less than 0.6 mm, and the size of the second side of the anode electrode piece exceeding the cathode electrode piece in the direction parallel to the surface of the electrode piece and perpendicular to the second side is also less than 0.6 mm.

[0009] Since the size of the first side of the anode electrode piece exceeding the cathode electrode piece in the direction parallel to the surface of the electrode piece and perpendicular to the first side is less than 0.6 mm, and the size of the second side of the anode electrode piece exceeding the cathode electrode piece is also less than 0.6 mm, the space occupied by the AC-Overhang structure of the battery cell in the two directions of the first side and the second side of the electrode piece is greatly reduced, the space utilization inside the battery cell is improved, and the energy density of the battery cell is improved.

[0010] Optionally, the bending stiffness of the electrode piece is wherein b is the length of the first side, m1 is the mass of the electrode piece, 0.64 is the sine value of the angle between the electrode piece and the horizontal plane, and 0.4 is the instability coefficient of the electrode piece.

[0011] Optionally, the bending stiffness of the electrode piece is wherein 0.4 and 0.2 are both instability coefficients of the electrode piece.

[0012] Since the electrode piece has a certain bending stiffness, the stacking process of the electrode piece can be quickly completed by a clamp during the production of the battery cell, which is beneficial to reducing the space occupied by the AC-Overhang structure and improving the production efficiency. In the two adjacent electrode pieces, the size of the first side of the anode electrode piece exceeding the cathode electrode piece in the direction parallel to the surface of the electrode piece and perpendicular to the first side is less than 0.4 mm, and the size of the first side of the anode electrode piece exceeding the cathode electrode piece in the direction parallel to the surface of the electrode piece and perpendicular to the second side is also less than 0.4 mm.

[0013] Since the size of the first side of the anode electrode piece exceeding the cathode electrode piece in the direction parallel to the surface of the electrode piece and perpendicular to the first side is less than 0.4 mm, and the size of the second side of the anode electrode piece exceeding the cathode electrode piece is also less than 0.4 mm, the space occupied by the AC-Overhang structure of the battery cell in the two directions of the first side and the second side of the electrode piece is further reduced, the space utilization inside the battery cell is improved, and the energy density of the battery cell is improved. Optionally, the first side and the second side of each electrode piece are perpendicular to each other, each electrode piece further includes a fourth side parallel to the first side thereof, and in the two adjacent electrode pieces, the size of the fourth side of the anode electrode piece exceeding the cathode electrode piece in the direction parallel to the surface of the electrode piece and perpendicular to the fourth side is less than 0.6 mm.

[0014] In this way, the AC-Overhang size of the battery cell in the first side edge and the second side edge of the electrode tab is reduced, and the space occupied by the AC-Overhang in the fourth side edge of the electrode tab is also reduced, thereby further improving the energy density of the battery cell.

[0015] Optionally, the first side edge and the second side edge of each electrode tab are perpendicular to each other, and each electrode tab further includes a fourth side edge parallel to the first side edge, and in the two adjacent electrode tabs, the fourth side edge of the anode tab exceeds the cathode tab by a size a, 0.4mm≤a<0.6mm in the direction parallel to the surface of the electrode tab and perpendicular to the fourth side edge.

[0016] In the two adjacent electrode tabs, the anode tab exceeds the cathode tab by 0.4mm≤a<0.6mm in the first side edge and the second side edge, thereby further reducing the risk of lithium precipitation of the anode tab in the fourth side edge, so that the processing precision of the electrode tab has a larger fault tolerance space, thereby reducing the production difficulty. In this way, the cost can be saved by reducing the processing precision of the production equipment, and the production efficiency can be improved by reducing the processing difficulty.

[0017] Optionally, in the two adjacent electrode tabs, the third side edge of the anode tab exceeds the cathode tab by a size less than 0.6mm in the direction parallel to the surface of the electrode tab and perpendicular to the third side edge.

[0018] In this way, since the four edges of the anode tab exceed the cathode tab by a size less than 0.6mm in the four directions parallel to the surface of the electrode tab and perpendicular to the edges in the two adjacent electrode tabs, the space occupied by the AC-Overhang of the four edges of the battery cell is reduced, thereby further increasing the energy density of the battery cell.

[0019] Optionally, each electrode tab includes a composite current collector and an active material layer coated on one side of the composite current collector, and the composite current collector includes a porous polymer substrate and a conductive layer combined on one side of the porous polymer substrate, and the active material layer is coated on the other side of the conductive layer.

[0020] By combining the porous polymer substrate and the conductive layer to form the composite current collector, the separator between the electrode tabs is not required, thereby reducing the difficulty of stacking the electrode tabs, and the structure of the composite current collector enables the electrode tab to have a certain bending stiffness, thereby facilitating the rapid stacking of the electrode tabs by means of a clamp.

[0021] Optionally, the battery cell further includes a separator arranged between the two adjacent electrode tabs.

[0022] The single electrode tab includes a conductive layer and an active material layer coated on the surface of the conductive layer.

[0023] Optionally, the bending stiffness of the separator is less than 0.5N / mm2. Wherein, b is the first side length, m2 is the diaphragm mass, 0.64 is the sine value of the angle between the pole piece and the horizontal plane, and 0.4 is the instability coefficient of the diaphragm.

[0024] Since the diaphragm has a certain bending stiffness, it is convenient for the diaphragm to align with the edges of the pole piece during stacking of the pole piece, that is, in the direction parallel to the pole piece, it is beneficial to reduce the spacing between each side of the diaphragm and the corresponding side of the pole piece, thereby improving the efficiency of the pole piece stacking.

[0025] Optionally, the battery cell includes two outermost pole pieces at both ends of the stacking direction, and intermediate layer pole pieces between the two outermost pole pieces, and each intermediate layer pole piece is provided with a hole for ion passing.

[0026] By respectively providing holes for ion passing in the pole pieces at the intermediate layer position, wherein the anode hole provided in the anode pole piece enables lithium ion migration to occur on both sides of the anode material layer during charging and discharging of the battery cell, and similarly, the cathode hole provided in the cathode pole piece enables lithium ion migration to occur on both sides of the cathode material layer during charging and discharging of the battery cell, which makes the lithium ion migration between the anode pole piece and the cathode pole piece stronger, thereby improving the charging and discharging rate of the battery cell.

[0027] Optionally, the active material layer thickness of at least one outermost pole piece is less than the active material layer thickness of the intermediate layer pole piece.

[0028] Since lithium ion migration of the outermost pole piece can only occur on one side of the pole piece, the amount of lithium ions that can be absorbed and released by the outermost pole piece is less than that of the intermediate layer pole piece. In this way, the active material layer thickness of the outermost pole piece is set to be less than that of the intermediate layer pole piece, which does not affect the efficiency of lithium ion migration of the outermost pole piece during charging and discharging, and can also reduce the overall thickness of the battery cell and improve the energy density of the battery cell.

[0029] According to the second aspect of the present application, the present application also discloses a device for producing the above-mentioned battery cell, which comprises a clamp for stacking a plurality of pole pieces, the clamp comprising a bottom plate for supporting a plurality of pole pieces, and a first baffle plate for abutting the first side of the plurality of pole pieces, so that in the two adjacent pole pieces, the size of the first side of the anode pole piece exceeds that of the cathode pole piece by less than 0.6mm in the direction parallel to the surface of the pole piece and perpendicular to the first side; the clamp further comprises a second baffle plate for abutting the second side of the plurality of pole pieces, so that in the two adjacent pole pieces, the size of the second side of the anode pole piece exceeds that of the cathode pole piece by less than 0.6mm in the direction parallel to the surface of the pole piece and perpendicular to the second side.

[0030] The first baffle plate and the second baffle plate form a second included angle, and the first included angle is equal to the second included angle.

[0031] In this way, when the pole pieces are stacked, the first side edge and the second side edge of the pole pieces are constrained by the first baffle and the second baffle of the clamp, so that, in the two adjacent pole pieces, the size of the first side edge of the anode pole piece exceeding the cathode pole piece is less than 0.6 mm in the direction parallel to the surface of the pole piece and perpendicular to the first side edge, and the size of the second side edge of the anode pole piece exceeding the cathode pole piece is less than 0.6 mm in the direction parallel to the surface of the pole piece and perpendicular to the second side edge.

[0032] Optionally, a third included angle exists between the bottom plate and the horizontal plane, so that, under the action of gravity of the pole pieces, the first side edges of the plurality of pole pieces abut against the first baffles, and the second side edges of the plurality of pole pieces abut against the second baffles.

[0033] Since the third included angle exists between the bottom plate and the horizontal plane, the surface of the bottom plate forms an inclined plane relative to the horizontal plane, so that, when the pole pieces are stacked, the pole pieces are facilitated to move downward along the surface of the bottom plate under the action of gravity of the pole pieces, so that the first side edges of the plurality of pole pieces abut against the first baffles, and the second side edges of the plurality of pole pieces abut against the second baffles, thereby achieving that the size of the first side edge of the anode pole piece exceeding the cathode pole piece is reduced to within 0.6 mm in the direction parallel to the surface of the pole piece and perpendicular to the first side edge, and the size of the second side edge of the anode pole piece exceeding the cathode pole piece is reduced to within 0.6 mm in the direction parallel to the surface of the pole piece and perpendicular to the second side edge. Optionally, the device further comprises a driving device for driving the clamp to vibrate, and the driving device is in transmission connection with the clamp.

[0034] The driving device is in transmission connection with the clamp, so that the clamp generates continuous vibration with high frequency and low amplitude, and the pole pieces in the clamp are prompted to move to one end of the first baffle and the second baffle, so that the first side edges and the second side edges of the plurality of pole pieces abut against the first baffle and the second baffle, respectively.

[0035] According to the third aspect of the present application, the embodiments of the present application further disclose a method for producing the above-mentioned battery cell, comprising:

[0036] Preparation of the pole pieces, including preparation of anode pole pieces and cathode pole pieces; bending stiffness of the pole pieces wherein b is the length of the first side edge, m1 is the mass of the pole piece, θ is the included angle between the pole piece and the horizontal plane, K1 is the instability coefficient of the pole piece, the value range of K1 is 0.2-4, and the value range of θ is between 40-70 degrees; each pole piece has at least a first side edge, a second side edge and a third side edge, and a first included angle exists between the first side edge and the second side edge;

[0037] Connection of the tabs, the tabs are electrically connected with the third side edges of the corresponding pole pieces;

[0038] Stacking the plurality of electrode sheets, and alternately stacking the anode electrode sheet and the cathode electrode sheet in the jig to make the first side edge and the second side edge of the plurality of electrode sheets respectively adhere to the first baffle and the second baffle of the jig; the third included angle between the bottom plate of the jig and the horizontal plane is consistent with the first included angle, and the end of the first baffle and the second baffle where the first baffle and the second baffle are gathered is lower than the end of the first baffle and the second baffle where the first baffle and the second baffle are dispersed.

[0039] Packaging the electrode core, and fixing the stacked electrode sheet in the packaging shell.

[0040] By placing the electrode sheet with bending stiffness in the jig, controlling the first baffle and the second baffle of the jig to respectively adhere to the first side edge and the second side edge of the electrode sheet, the first side edge and the second side edge of the electrode sheet can be constrained; because the third included angle exists between the bottom plate and the horizontal plane, the surface of the bottom plate forms an inclined plane relative to the horizontal plane, so that the electrode sheet automatically moves downward along the surface of the bottom plate under the action of its own gravity, so that the first side edge of the plurality of electrode sheets adheres to the first baffle, and the second side edge of the plurality of electrode sheets adheres to the second baffle. In this way, among the two adjacent electrode sheets, in the direction parallel to the surface of the electrode sheet and perpendicular to the first side edge, the size of the first side edge of the anode electrode sheet exceeds that of the cathode electrode sheet by less than 0.6 mm; and in the direction parallel to the surface of the electrode sheet and perpendicular to the second side edge, the size of the second side edge of the anode electrode sheet exceeds that of the cathode electrode sheet by less than 0.6 mm. At the same time, the jig can realize the rapid stacking of the electrode sheet, and increase the production efficiency of the electrode core.

[0041] Optionally, in the direction parallel to the surface of the electrode sheet and perpendicular to the first side edge, the spacing between the first side edges of the two adjacent electrode sheets is less than 0.6 mm; and in the direction parallel to the surface of the electrode sheet and perpendicular to the second side edge, the spacing between the second side edges of the two adjacent electrode sheets is less than 0.6 mm.

[0042] In this way, by reducing the space occupied by the AC-Overhang structure of the electrode core in the two directions of the first side edge and the second side edge of the electrode sheet, the energy density of the electrode core is improved.

[0043] Optionally, the preparation of the electrode sheet comprises:

[0044] Preparation of the composite current collector, and compounding the conductive layer on one side of the porous polymer substrate to form the composite current collector; wherein the composite current collector comprises an anode composite current collector and a cathode composite current collector, the anode composite current collector comprises an anode porous polymer substrate and an anode conductive layer, and the cathode composite current collector comprises a cathode porous polymer substrate and a cathode conductive layer;

[0045] Coating the active material layer, and coating the active material layer on the surface of the conductive layer away from the porous polymer substrate;

[0046] The anode active material layer is coated on the side of the anode conductive layer away from the anode porous polymer substrate, and the cathode active material layer is coated on the side of the cathode conductive layer away from the cathode porous polymer substrate.

[0047] By compounding the porous polymer substrate with the conductive layer to form a composite current collector, the separator is not required between the electrode sheets, the difficulty of stacking the electrode sheets is reduced, and the structure of the composite current collector enables the electrode sheets to have a certain bending stiffness, facilitating the rapid stacking of the electrode sheets by means of the clamp.

[0048] Optionally, the step of preparing the electrode sheet further comprises: preparing a separator, the separator comprising an anode separator consistent in size with the anode electrode sheet and a cathode separator consistent in size with the cathode electrode sheet, the separator having a first side edge and a second side edge consistent with the electrode sheet;

[0049] The stiffness of the separator wherein b is the length of the first side edge, m2 is the mass of the separator, K2 is the instability coefficient of the separator, the value range of K2 is 0.2-0.4, and θ is the included angle between the electrode sheet and the horizontal plane, the value range of θ is between 40-70 degrees;

[0050] The step of stacking the electrode sheets further comprises: placing the separator between the anode electrode sheet and the cathode electrode sheet, so that the first side edge of the plurality of electrode sheets and the separator is attached to the first baffle of the clamp, and the second side edge of the electrode sheet and the separator is attached to the second baffle.

[0051] Since the separator has a certain bending stiffness, the edges of the separator and the electrode sheet are aligned when the electrode sheets are stacked, that is, in the direction parallel to the surface of the electrode sheet, the distance between the edges of the separator and the corresponding edges of the electrode sheet is reduced, and the efficiency of the electrode sheet stacking is improved.

[0052] Optionally, before the step of packaging the battery cell, the cathode electrode sheet is deactivated:

[0053] The first side edge of the cathode electrode sheet is deactivated so that, in the direction parallel to the surface of the electrode sheet, the size of the edge of the anode active material layer of the anode electrode sheet located at the first side edge exceeding the edge of the cathode active material layer of the cathode electrode sheet is less than 0.6 mm; and the second side edge of the cathode electrode sheet is deactivated so that, in the direction parallel to the surface of the electrode sheet, the size of the edge of the anode active material layer of the anode electrode sheet located at the second side edge exceeding the edge of the cathode active material layer of the adjacent cathode electrode sheet is less than 0.6 mm.

[0054] By deactivating the active material layer of the cathode electrode sheet, it is ensured that, in the direction parallel to the electrode sheet, the edge of the active material layer of the anode electrode sheet at the first side edge and the second side edge exceeds the cathode electrode sheet, and the exceeding size is between 0-0.6 mm, avoiding the phenomenon of lithium precipitation of the anode electrode sheet.

[0055] Optionally, holes for ion passing are opened on the surface of the conductive layer.

[0056] By setting holes for ion passing on the surface of the conductive layer, the migration of lithium ions between the anode and cathode electrode sheets is stronger, thereby improving the charge and discharge rate of the battery cell.

[0057] Optionally, the battery cell comprises two outermost electrode sheets at the two ends of the stacking direction, and intermediate electrode sheets between the two outermost electrode sheets.

[0058] The thickness of the active material layer of at least one outermost electrode sheet is less than that of the intermediate electrode sheets.

[0059] Since the lithium ion migration of the outermost electrode sheet can only occur on one side of the electrode sheet, the amount of lithium ions that can be absorbed and released by the outermost electrode sheet is less than that of the intermediate electrode sheets. Therefore, by setting the thickness of the active material layer of the outermost electrode sheet to be less than that of the intermediate electrode sheets, the efficiency of lithium ion migration of the outermost electrode sheet during charging and discharging is not affected, and the overall thickness of the battery cell is reduced, thereby improving the energy density of the battery cell.

[0060] Optionally, the method further comprises, before the packaging step:

[0061] The vibration fixture is controlled to generate mechanical vibration for causing the first side edge and the second side edge of the plurality of electrode sheets to respectively adhere to the first baffle and the second baffle under the action of gravity.

[0062] By controlling the vibration fixture to generate continuous vibration with high frequency and low amplitude, the electrode sheets in the fixture move towards the end where the first baffle and the second baffle are gathered, thereby causing the first side edge and the second side edge of the plurality of electrode sheets to respectively adhere to the first baffle and the second baffle. This achieves the following results: in the direction parallel to the surface of the electrode sheets and perpendicular to the first side edge, the size of the first side edge of the anode electrode sheet exceeding the cathode electrode sheet is reduced to within 0.6 mm; and in the direction parallel to the surface of the electrode sheets and perpendicular to the second side edge, the size of the second side edge of the anode electrode sheet exceeding the cathode electrode sheet is reduced to within 0.6 mm.

[0063] The electric core, the production equipment and the preparation method thereof disclosed in the application, in the adjacent two pole pieces, in the direction parallel to the pole piece surface and perpendicular to the first side edge, the first side edge of the anode pole piece exceeds the size of the cathode pole piece within 0.6 mm, in the direction parallel to the pole piece surface and perpendicular to the second side edge, in the adjacent two pole pieces, the second side edge of the anode pole piece exceeds the size of the cathode pole piece within 0.6 mm, so that the space occupied by the AC-Overhang structure in the first side edge and the second side edge of the pole piece is reduced at least, and the energy density of the electric core is improved. And the anode pole piece and the cathode pole piece are quickly aligned by the clamp during production, the accuracy requirement of the pole piece dragging and placing is greatly reduced, the production efficiency of the electric core is increased, and the production cost is reduced in terms of equipment and process difficulty. BRIEF DESCRIPTION OF DRAWINGS

[0064] In order to more clearly illustrate the technical solutions in the specific embodiments of the application, the drawings needed to be used in the specific embodiment description will be briefly introduced below. In all the drawings, similar elements or parts are generally identified by similar reference signs. In the drawings, each element or part is not necessarily drawn according to the actual proportion.

[0065] Fig. 1 is a structural schematic diagram of an electric core in an embodiment of the application;

[0066] Fig. 2 is a structural schematic diagram of a pole piece in an embodiment of the application;

[0067] Fig. 3 is a structural schematic diagram of an anode pole piece in an embodiment of the application;

[0068] Fig. 4 is a structural schematic diagram of a cathode pole piece in an embodiment of the application;

[0069] Fig. 5 is a structural schematic diagram of an electric core in another embodiment of the application;

[0070] Fig. 6 is a structural schematic diagram of an electric core in another embodiment of the application;

[0071] Fig. 7 is a sectional view of an electric core in an embodiment of the application;

[0072] Fig. 8 is another sectional view of an electric core in an embodiment of the application;

[0073] Fig. 9 is a structural schematic diagram of a clamp in an embodiment of the application;

[0074] Fig. 10 is a schematic diagram of the use state of a clamp in an embodiment of the application;

[0075] Fig. 11 is a schematic diagram of the local structure of an electric core in an embodiment of the application;

[0076] Fig. 12 is a flow chart of an electric core production method in an embodiment of the application;

[0077] Fig. 13 is a flow chart of a method of manufacturing an electric cell according to another embodiment of the present application.

[0078] In the drawings: 1: electrode sheet, 1a: anode electrode sheet, 10a: anode material layer, 11a: anode porous polymer substrate, 12a: anode conductive layer, 120a: anode hole, 1b: cathode electrode sheet, 10b: cathode material layer, 11b: cathode porous polymer substrate, 12b: cathode conductive layer, 120b: cathode hole, 11: first side edge, 12: second side edge, 13: third side edge, 14: fourth side edge; 2: electrode tab, 21: anode electrode tab, 22: cathode electrode tab; 3: separator; 4: jig, 40: base plate, 41: first baffle, 42: second baffle. DETAILED DESCRIPTION

[0079] For the purpose of promoting the understanding of the present application, the present application will be described in further detail below with reference to the drawings and specific embodiments. It should be noted that when an element is described as "fixed to" another element, it can be directly on the other element or one or more intervening elements can be present therebetween. When an element is described as "connected to" another element, it can be directly connected to the other element or one or more intervening elements can be present therebetween. The terms "upper", "lower", "inner", "outer", "vertical", "horizontal", and the like as used in the present specification and in the appended claims are used for the purpose of illustrating specific embodiments of the present application and simplifying the present description only and are not intended to limit or confine the present application to the positions illustrated unless such a limiting interpretation appears inescapable from the context. Furthermore, the terms "first", "second", and the like are used merely as identifiers and are not intended to confine the scope of the present application to any relative importance. The terms "comprise", "include", and the like are intended to mean that the elements or components present in the preceding description are encompassed by the term, and are not intended to exclude other elements or components. The terms "connected" or "coupled" are not limited to direct connections or physical connections, but can include indirect connections or physical connections unless otherwise defined in context. Unless otherwise defined, the terms "parallel", "perpendicular", and "identical" as used in the embodiments of the present application include the cases of "strictly parallel", "strictly perpendicular", and "strictly identical" as well as the cases of "approximately parallel", "approximately perpendicular", and "approximately identical" that include certain errors. For example, "approximately" as described above can mean that the difference between the compared objects is within 10% or 5% of the average value of the compared objects. In the following description of the embodiments of the present application, when the number of a component or element is not specifically indicated, it means that the component or element can be one or more, or can be understood as at least one. "At least one" means one or more, and "a plurality of" means at least two.

[0080] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description of the application herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. All publications, patent applications, patents, and other references mentioned herein are incorporated by reference in their entirety for the teachings relevant to the sentence and / or paragraph in which the reference is presented.

[0081] In addition, the technical features involved in the different embodiments of the application described below can be combined with each other as long as there is no conflict. Obviously, the described embodiments are part of the embodiments of the application, not all.

[0082] The electric core disclosed in the application, as shown in FIGS. 1-4, comprises a plurality of laminated pole pieces 1, a plurality of tabs 2 corresponding to the plurality of pole pieces 1, each pole piece 1 has at least a first side edge 11, a second side edge 12 and a third side edge 13, and a first included angle between the first side edge 11 and the second side edge 12. The pole piece 1 is further divided into an anode pole piece 1a and a cathode pole piece 1b according to the type of reaction occurring during electrochemical reaction. The plurality of laminated pole pieces 1 includes at least one anode pole piece 1a and one cathode pole piece 1b, and the anode pole piece 1a and the cathode pole piece 1b are alternately laminated. The tab 2 includes an anode tab 21 arranged on the anode pole piece 1a and a cathode tab 22 arranged on the cathode pole piece 1b. Among them, the anode tab 21 is arranged on the third side edge 13 of the anode pole piece 1a, and the cathode tab 22 is arranged on the third side edge 13 of the cathode pole piece 1b.

[0083] In the direction parallel to the surface of the pole piece 1 and perpendicular to the first side edge 11, the size of the first side edge 11 of the anode pole piece 1a exceeding the adjacent cathode pole piece 1b is less than 0.6mm, and the size of the second side edge 12 of the anode pole piece 1a exceeding the adjacent cathode pole piece 1b is less than 0.6mm.

[0084] Since the size of the first side edge 11 of the anode pole piece 1a exceeding the cathode pole piece 1b is limited within 0.6mm in the direction parallel to the surface of the pole piece and perpendicular to the first side edge, and the size of the second side edge 12 of the anode pole piece 1a exceeding the cathode pole piece 1b is limited within 0.6mm, the space occupied by the AC-Overhang structure of the electric core in the two directions of the first side edge 11 and the second side edge 12 of the pole piece 1 is greatly reduced, and the energy density of the electric core is improved.

[0085] In another embodiment of the present application, in the two adjacent pole pieces 1, the size of the first side edge 11 of the anode pole piece 1a exceeding the cathode pole piece 1b in the direction parallel to the surface of the pole piece 1 and perpendicular to the first side edge is less than 0.4 mm, and the size of the first side edge 11 of the anode pole piece 1a exceeding the cathode pole piece 1b in the direction parallel to the surface of the pole piece 1 and perpendicular to the second side edge 12 is less than 0.4 mm. Thus, the space occupied by the AC-Overhang structure of the battery cell in the two directions of the first side edge 11 and the second side edge 12 of the pole piece 1 is further reduced, and the energy density of the battery cell is improved.

[0086] In an embodiment of the present application, the pole piece 1 is a rigid pole piece with a certain bending resistance, specifically, the bending stiffness D1 of the pole piece 1 satisfies wherein b is the length of the first side edge, m1 is the mass of the pole piece, and 0.2 and 0.4 are two end point values of the pole piece instability coefficient K1, and the value range of K1 is 0.2-0.4 (including 0.2 and 0.4). In another embodiment of the present application, the bending stiffness D1 of the pole piece 1 satisfies wherein the bending stiffness D1 of the pole piece 1 satisfies wherein E1 is the equivalent elastic modulus of the pole piece, t is the thickness of the pole piece, and υ1 is the Poisson's ratio of the pole piece, and E1 and υ1 are inherent parameters related to the material of the pole piece, and are fixed values when the material of the pole piece is fixed.

[0087] For example, in the present embodiment, when the equivalent elastic modulus E1 of the pole piece 1 is 10.48 GPa, the thickness t is 0.106 mm, and the Poisson's ratio υ1 is 0.3, the bending stiffness D1 of the pole piece 1 is 1.143 N·mm. The pole piece instability coefficient K1 is 0.4, the length b of the first side edge 11 is 71 mm, the mass m1 of the pole piece is 0.001266 Kg, and the inclination angle θ of the pole piece 1 is 60 degrees.

[0088] Since the pole piece 1 has a certain bending stiffness, the stacking process of the pole piece can be quickly completed by the clamp, which is not only conducive to reducing the space occupied by the AC-Overhang structure, but also improves the production efficiency.

[0089] In another embodiment of the present application, as shown in FIG. 5, the first side edge 11 and the second side edge 12 of the pole piece 1 are perpendicular to each other, i.e., the first included angle is 90 degrees. The pole piece 1 further comprises a fourth side edge 14 parallel to the first side edge 11. In the direction parallel to the surface of the pole piece 1 and perpendicular to the fourth side edge 14, the fourth side edge 14 of the anode pole piece 1a exceeds the adjacent cathode pole piece 1b by a size less than 0.6 mm, i.e., the fourth side edge 14 of the anode pole piece 1a exceeds the fourth side edge 14 of the adjacent cathode pole piece 1b by a misalignment size less than 0.6 mm. Since in the direction parallel to the surface of the pole piece 1 and perpendicular to the fourth side edge 14, the fourth side edge 14 of the anode pole piece 1a exceeds the adjacent cathode pole piece 1b by a size less than 0.6 mm, the AC-Overhang space occupied by the pole piece 1 in the fourth side edge 14 direction is reduced, further improving the energy density of the battery cell.

[0090] In another embodiment of the present application, as shown in FIG. 1, in the two adjacent pole pieces 1, in the direction parallel to the surface of the pole piece 1 and perpendicular to the first side edge, the first side edge 11 of the anode pole piece 1a exceeds the cathode pole piece 1b by a size less than 0.4 mm, and in the direction parallel to the surface of the pole piece 1 and perpendicular to the second side edge 12, the first side edge 11 of the anode pole piece 1a exceeds the cathode pole piece 1b by a size less than 0.4 mm. In the direction parallel to the surface of the pole piece 1 and perpendicular to the fourth side edge 14, the fourth side edge 14 of the anode pole piece 1a exceeds the adjacent cathode pole piece 1b by a size between 0.4-0.6 mm, i.e., in the direction parallel to the surface of the pole piece 1, the fourth side edge 14 of the anode pole piece 1a exceeds the fourth side edge 14 of the adjacent cathode pole piece 1b by a misalignment size a, 0.4 mm≤a<0.6 mm. Since the greater the size of the edge of the anode pole piece 1a exceeding the cathode pole piece 1b in the two adjacent pole pieces, the lower the risk of lithium precipitation on the surface of the anode pole piece 1a, and the lower the requirement for the precision of the processing equipment itself. In this embodiment, compared to the first side edge and the second side edge, the size of the anode pole piece 1a exceeding the cathode pole piece 1b at the fourth side edge 14 is greater in the two adjacent pole pieces 1, thus reducing the risk of lithium precipitation on the fourth side edge 14 of the anode pole piece 1a, providing a larger fault tolerance space for the processing precision of the pole piece 1, thus reducing the production difficulty. This can not only save costs by reducing the processing precision of the production equipment, but also improve production efficiency by reducing processing difficulty.

[0091] In another embodiment of the present application, as shown in FIG. 6, the pole piece 1 is rectangular, and in the two adjacent pole pieces 1 stacked with each other, the third side 13 of the anode pole piece 1a exceeds the third side 13 of the cathode pole piece 1b in the direction parallel to the surface of the pole piece 1 and perpendicular to the third side 13, and the size of the third side 13 of the anode pole piece 1a exceeding the third side 13 of the adjacent cathode pole piece 1b is less than 0.6 mm, i.e., the size of the third side 13 of the anode pole piece 1a exceeding the third side 13 of the adjacent cathode pole piece 1b is less than 0.6 mm in the four directions parallel to the surface of the pole piece 1 and perpendicular to the edges. In this way, in the two adjacent pole pieces 1, the four edges of the anode pole piece 1a exceed the four edges of the cathode pole piece 1b in the four directions parallel to the surface of the pole piece 1 and perpendicular to the edges, and the size of the four edges of the anode pole piece 1a exceeding the four edges of the adjacent cathode pole piece 1b is less than 0.6 mm, i.e., the space occupied by the four edges AC-Overhang of the battery cell is reduced, further increasing the energy density of the battery cell.

[0092] As shown in FIGS. 3-4 and FIGS. 7-8, each pole piece of the present embodiment comprises a composite current collector and an active material layer coated on the surface of the composite current collector, and the composite current collector comprises a porous polymer substrate and a conductive layer combined with the single side surface of the porous polymer substrate. Specifically, the composite current collector, the porous polymer substrate, the conductive layer and the active material layer corresponding to the anode pole piece 1a are anode composite current collector, anode porous polymer substrate 11a, anode conductive layer 12a and anode material layer 10a respectively; the composite current collector, the porous polymer substrate, the conductive layer and the active material layer corresponding to the cathode pole piece 1b are cathode composite current collector, cathode porous polymer substrate 11b, cathode conductive layer 12b and cathode material layer 10b respectively. The anode pole piece 1a comprises an anode composite current collector and an anode material layer 10a arranged on the surface of the anode composite current collector, and the anode composite current collector comprises an anode porous polymer substrate 11a and an anode conductive layer 12a combined with the single side surface of the anode porous polymer substrate 11a, for example, the anode conductive layer 12a is coated on the surface of the anode porous polymer substrate 11a by vacuum evaporation to realize the composite process of the anode porous polymer substrate 11a and the anode conductive layer 12a. The anode material layer 10a is arranged on the surface of the anode conductive layer 12a.

[0093] The cathode pole piece 1b comprises a cathode composite current collector and a cathode material layer 10b arranged on the surface of the cathode composite current collector, and the cathode composite current collector comprises a cathode porous polymer substrate 11b and a cathode conductive layer 12b combined with the single side surface of the cathode porous polymer substrate 11b, for example, the cathode conductive layer 12b is coated on the surface of the cathode porous polymer substrate 11b by vacuum evaporation to realize the composite process of the cathode porous polymer substrate 11b and the cathode conductive layer 12b. The cathode material layer 10b is arranged on the surface of the cathode conductive layer 12b.

[0094] As shown in Fig. 8, due to the alternate stacking of the anode electrode sheet 1a and the cathode electrode sheet 1b, each cathode electrode sheet 1b in the middle layer is located between two anode electrode sheets 1a, one of which is located on the side of the cathode material layer 10b of the cathode electrode sheet 1b, and the other of which is located on the side of the cathode porous polymer substrate 11b of the cathode electrode sheet 1b; similarly, each anode electrode sheet 1a in the middle layer is located between two cathode electrode sheets 1b, one of which is located on the side of the anode material layer 10a of the anode electrode sheet 1a, and the other of which is located on the side of the anode porous polymer substrate 11a of the anode electrode sheet 1a.

[0095] In this embodiment, the conductive layer of each middle layer electrode sheet is provided with holes for ion passage. That is, the anode conductive layer 12a and the cathode conductive layer 12b in the middle layer are both distributed with holes for lithium ion passage, wherein the holes provided on the anode conductive layer 12a are anode holes 120a, and the holes provided on the cathode conductive layer 12b are cathode holes 120b.

[0096] In this way, during charging, lithium ions in the cathode electrode sheet 1b located in the middle position enter the electrolyte from the cathode material layer 10b of the cathode electrode sheet 1b, thereby releasing a large amount of lithium ions near the cathode electrode sheet 1b. On the one hand, part of these lithium ions move to the anode electrode sheet 1a located on the side of the cathode material layer 10b, and these lithium ions successively pass through the anode porous polymer substrate 11a of the anode electrode sheet 1a and the anode holes 120a of the anode conductive layer 12a, and finally undergo a reduction reaction (obtain electrons) in the anode material layer 10a of the anode electrode sheet 1a to form lithium atoms embedded in the anode material layer 10a; on the other hand, another part of the lithium ions move to the anode electrode sheet 1a located on the side of the cathode porous polymer substrate 11b in the opposite direction, and these lithium ions successively pass through the cathode holes 120b of the cathode conductive layer 12b and the cathode porous polymer substrate 11b of the cathode electrode sheet 1b, and finally undergo a reduction reaction (obtain electrons) in the anode material layer 10a of the anode electrode sheet 1a to form lithium atoms embedded in the anode material layer 10a.

[0097] During discharging, lithium atoms in the anode tab 1a in the middle position react with oxygen (lose electrons) to form lithium ions, which are then deintercalated from the anode material layer 10a of the anode tab 1a, thereby releasing a large number of lithium ions. On one hand, part of the lithium ions move to the cathode tab 1b on the side of the anode material layer 10a, and under the action of the electric field, the lithium ions pass through the cathode porous polymer base material 11b and the cathode hole 120b of the cathode conductive layer 12b of the cathode tab 1b on the side in turn, and finally, the lithium ions react with oxygen (gain electrons) in the cathode material layer 10b of the cathode tab 1b and return to the cathode material layer 10b. On the other hand, the other part of the lithium ions move to the cathode tab 1b on the side of the anode porous polymer base material 11a in the opposite direction, and under the action of the electric field, the lithium ions pass through the anode hole 120a of the anode conductive layer 12a and the anode porous polymer base material 11a of the anode tab 1a in turn, and finally, the lithium ions react with oxygen (gain electrons) in the cathode material layer 10b of the cathode tab 1b and return to the cathode material layer 10b.

[0098] Therefore, the anode hole 120a of the anode conductive layer 12a arranged in the middle layer enables the migration of lithium ions to occur on both sides of the anode material layer 10a during charging and discharging of the battery cell, and similarly, the cathode hole 120b of the cathode tab 1b arranged in the middle layer enables the migration of lithium ions to occur on both sides of the cathode material layer 10b during charging and discharging of the battery cell, which makes the migration of lithium ions between the anode tab 1a and the cathode tab 1b stronger, thereby improving the charging and discharging rate of the battery cell.

[0099] The battery cell includes two outermost tabs 1 at both ends in the stacking direction, and a middle tab 1 between the two outermost tabs 1. Since the migration of lithium ions of the outermost tab 1 can only occur on one side, the amount of lithium ions that can be absorbed and released by the outermost tab 1 is less than that of the middle tab 1. Therefore, in the embodiment, the thickness of the active material layer of at least one outermost tab 1 is less than that of the active material layer of the middle tab 1. The two outermost tabs 1 can be tabs of the same polarity or tabs of different polarities.

[0100] In an embodiment of the present application, as shown in FIGS. 7 and 8, the thickness of the active material layer of the two outermost tabs 1 of the battery cell is less than that of the active material layer of the middle tab 1. In this way, the efficiency of the migration of lithium ions during charging and discharging of the outermost tab 1a is not affected, and the overall thickness of the battery cell is reduced, thereby improving the energy density of the battery cell.

[0101] In yet another embodiment of the present application, as shown in FIG. 11, the pole piece 1 comprises a conductive layer and an active material layer coated on the surface of the conductive layer, wherein the active material layer can be coated on one side of the conductive layer or on both sides of the conductive layer. The difference between this embodiment and the above embodiments is that the battery cell further comprises a separator 3 arranged between the pole pieces 1.

[0102] In this embodiment, the bending stiffness of the separator 3 is wherein b is the length of the first side edge 11, m2 is the mass of the separator 3, θ is the included angle between the pole piece 1 and the horizontal plane, and K2 is the buckling coefficient of the separator 3, the value range of K2 is 0.2-0.4, and the value range of θ is between 40-70 degrees. In this embodiment, the bending stiffness of the separator 3 is E2 is the equivalent elastic modulus of the separator 3, t is the thickness of the separator 3 (the distance between the first side edge and the fourth side edge), and υ2 is the corresponding Poisson's ratio of the separator material. In this embodiment, E2 and υ2 are inherent parameters related to the separator material, and are fixed values when the material of the separator is fixed.

[0103] In this embodiment, the separator 3 has a certain bending stiffness, which facilitates the alignment of the edges of the separator 3 and the pole piece 1 during the stacking of the pole pieces, i.e., in the direction parallel to the surface of the pole piece, the distance between the edges of the separator and the corresponding edges of the pole piece is reduced, thereby improving the efficiency of the stacking of the pole pieces.

[0104] As shown in FIGS. 9 and 10, the present application further discloses an apparatus for producing the battery cell of the above embodiments, which comprises a clamp 4 for stacking a plurality of pole pieces 1, the clamp 4 comprising a bottom plate 40 for supporting the plurality of pole pieces 1, a first baffle plate 41 for abutting the first side edge 11 of the plurality of pole pieces 1, so that the size of the first side edge 11 of the anode pole piece 1a exceeding the adjacent cathode pole piece 1b in the direction parallel to the surface of the pole piece 1 and perpendicular to the first side edge 11 is less than 0.6 mm, and a second baffle plate 42 for abutting the second side edge 12 of the plurality of pole pieces 1, so that the size of the second side edge 12 of the anode pole piece 1a exceeding the adjacent cathode pole piece 1b in the direction parallel to the surface of the pole piece 1 and perpendicular to the second side edge 12 is less than 0.6 mm, wherein a first included angle exists between the first side edge 11 and the second side edge 12 of each pole piece 1, a second included angle exists between the first baffle plate 41 and the second baffle plate 42, and the first included angle is equal to the second included angle. In this embodiment, the first included angle and the second included angle are both 90 degrees, i.e., the first side edge 11 is perpendicular to the second side edge 12.

[0105] In this way, when the pole pieces are stacked, the first side edge and the second side edge of the pole pieces are constrained by controlling the first baffle and the second baffle of the clamp to be attached to the first side edge and the second side edge of the pole pieces respectively, so that, in the two adjacent pole pieces, the size of the first side edge of the anode pole piece exceeding the cathode pole piece in the direction parallel to the surface of the pole piece and perpendicular to the first side edge is less than 0.6 mm, and the size of the second side edge of the anode pole piece exceeding the cathode pole piece in the direction parallel to the surface of the pole piece and perpendicular to the second side edge is less than 0.6 mm.

[0106] The third included angle between the bottom plate 40 of the clamp 4 and the horizontal plane is between 40-70 degrees, so that the surface of the bottom plate 40 forms an inclined surface relative to the horizontal plane, so that the pole pieces 1 automatically move downward along the surface of the bottom plate 40 under the action of their own gravity, so that the first side edge 11 of the plurality of pole pieces 1 is attached to the first baffle 41, and the second side edge 12 of the plurality of pole pieces 1 is attached to the second baffle 42. The end of the first baffle 41 and the second baffle 42 gathered together is lower than the end of the two dispersed in the vertical direction. In this way, when the pole pieces 1 are stacked, the pole pieces 1 are moved to the end of the first baffle 41 and the second baffle 42 gathered together under the action of their own gravity by vibrating the clamp 4, until the first side edge 11 and the second side edge 12 of the plurality of pole pieces 1 are attached to the first baffle 41 and the second baffle 42 respectively. In this way, in the direction parallel to the surface of the pole piece 1 and perpendicular to the first side edge 11, the size of the first side edge 11 of the anode pole piece 1a exceeding the adjacent cathode pole piece 1b is less than 0.6 mm, and the size of the second side edge 12 of the anode pole piece 1a exceeding the adjacent cathode pole piece 1b is also less than 0.6 mm.

[0107] The production equipment of the battery cell also includes a driving device for driving the clamp 4 to vibrate, the clamp 4 is in transmission connection with the driving device, the driving device can include a connecting rod mechanism or a cam mechanism, or include an ultrasonic vibrator that realizes mechanical vibration by using piezoelectric effect or magnetostrictive effect, by transmission connection between the driving device and the clamp 4, so that the clamp 4 generates continuous vibration with high frequency and low amplitude, prompting the pole pieces 1 in the clamp 4 to move to the end of the first baffle 41 and the second baffle 42 gathered together, prompting the first side edge 11 and the second side edge 12 of the plurality of pole pieces 1 to be attached to the first baffle 41 and the second baffle 42 respectively.

[0108] The application also discloses a method for manufacturing a battery cell, as shown in FIG. 12, comprising the steps of:

[0109] S1, preparing pole pieces.

[0110] The preparation of the pole pieces includes:

[0111] The composite current collector is prepared by compounding the conductive layer on the surface of the porous polymer substrate on one side to form the composite current collector. The composite current collector includes an anode composite current collector and a cathode composite current collector according to the polarity of the pole piece 1. The anode composite current collector includes an anode porous polymer substrate and an anode conductive layer. The cathode composite current collector includes a cathode porous polymer substrate and a cathode conductive layer.

[0112] In this embodiment, the porous polymer substrate is a thin film layer with a thickness of 1-100 μm, and the material is a polymer, such as polyethylene, polypropylene, polyethylene terephthalate, polyimide, or polyphenylene sulfide in one or more combinations. The porous polymer substrate is a porous structure and can be directly used as a separator of an existing lithium battery. The electrolyte can flow through the pores on both sides of the porous polymer substrate.

[0113] The conductive layer is compounded on the surface of the porous polymer substrate by using existing processes, such as vacuum evaporation to coat the anode conductive layer on the surface of the anode porous polymer substrate to realize the compounding process of the anode porous polymer substrate and the anode conductive layer. Similarly, the cathode conductive layer is coated on the surface of the cathode porous polymer substrate by vacuum evaporation to realize the compounding process of the cathode porous polymer substrate and the cathode conductive layer. The material of the conductive layer includes any one or a combination of at least two of an aluminum layer, a copper layer, a silver layer, a gold layer, or an iron layer.

[0114] In this embodiment, the composite current collector formed by the compounding of the porous polymer substrate and the conductive layer has a certain bending stiffness. The bending stiffness referred to in the present application means that when the edge of the pole piece on one side is subjected to a pushing force parallel to the surface of the pole piece, the pushing force will not cause local deformation, but will be transmitted to the edge on the other side, so that the pole piece as a whole moves under the action of the pushing force. Specifically, the bending stiffness of the pole piece where b is the length of the first side edge, m1 is the mass of the pole piece, θ is the angle between the pole piece and the horizontal plane, and K1 is the instability coefficient, which is in the range of 0.2-0.4, and θ is in the range of 40-70 degrees. The bending stiffness of the pole piece E1 is the equivalent elastic modulus of the pole piece, t is the thickness of the pole piece (the distance between the first side edge and the fourth side edge), and υ1 is the Poisson's ratio of the pole piece. E1 and υ1 are inherent parameters related to the material of the pole piece and have fixed values when the material of the pole piece is fixed.

[0115] The conductive layer surface of the composite current collector is coated with an active material layer. The active material layer includes an anode material layer and a cathode material layer. Specifically, the anode conductive layer surface of the anode composite current collector is coated with an anode active material layer to form an anode electrode sheet, and the cathode conductive layer surface of the cathode composite current collector is coated with a cathode active material layer to form a cathode electrode sheet. The selection of the anode active material of the present application is not limited, and examples include graphite, silicon-carbon, silicon, lithium titanate, hard carbon, soft carbon, etc. The cathode material layer can use existing materials, such as lithium iron phosphate, lithium iron manganese phosphate, lithium cobaltate, or lithium nickel cobalt manganese oxide, etc.

[0116] By compounding the porous polymer substrate with the conductive layer to form a composite current collector, the separator between the electrode sheets is not required, reducing the difficulty of stacking the electrode sheets. At the same time, the composite current collector enables the electrode sheets to have a certain bending stiffness, facilitating the rapid stacking of the electrode sheets with the aid of a clamp.

[0117] In the present embodiment, the anode conductive layer and the cathode conductive layer are both distributed with pores for lithium ion passage, wherein the anode conductive layer is provided with anode pores, and the cathode conductive layer is provided with cathode pores. In this way, the anode pores provided on the anode conductive layer enable the migration of lithium ions to occur on both sides of the anode material layer during charging and discharging of the battery cell, and similarly, the cathode conductive pores provided on the cathode electrode sheet enable the migration of lithium ions to occur on both sides of the cathode material layer during charging and discharging of the battery cell. This makes the migration of lithium ions between the anode electrode sheet and the cathode electrode sheet stronger, thereby improving the charging and discharging rate of the battery cell.

[0118] The battery cell includes two outermost electrode sheets located at both ends in the stacking direction, and intermediate electrode sheets located between the two outermost electrode sheets. Since the lithium ion migration of the outermost electrode sheets can only occur on one side, the amount of lithium ions that can be absorbed and released by the outermost electrode sheets is less than that of the intermediate electrode sheets. Therefore, in the present embodiment, the thickness of the active material layer of at least one outermost electrode sheet is less than the thickness of the active material layer of the intermediate electrode sheets. The two outermost electrode sheets can be electrode sheets of the same polarity, or electrode sheets of different polarities.

[0119] In an embodiment of the present application, the thickness of the active material layer of the two outermost electrode sheets of the battery cell is less than the thickness of the active material layer of the intermediate electrode sheets. In this way, the effect of the outermost electrode sheets participating in lithium ion migration is not affected, and the overall thickness of the battery cell is reduced, thereby improving the energy density of the battery cell.

[0120] In addition, the present application only coats the active material on one side of the composite current collector, without the need for double-sided coating, thereby avoiding the limitations of double-sided alignment and the consistency of double-sided surface density, and the production efficiency is higher. The electrode sheets are cut to a predetermined size so that the electrode sheets have a first side edge, a second side edge, and a third side edge, and a first included angle between the first side edge and the second side edge.

[0121] In an embodiment of the present application, the pole piece is cut at a first included angle of 90 degrees, and the cut pole piece is rectangular, wherein the pole piece further comprises a fourth side, and the first side is parallel to the fourth side.

[0122] In an embodiment of the present application, the first side of the cathode pole piece and the first side of the anode pole piece are cut to the same size.

[0123] In another embodiment of the present application, as shown in FIG. 10, in a direction parallel to the surface of the pole piece and perpendicular to the first side, the distance between the first side and the fourth side of the anode pole piece is greater than the distance between the first side and the fourth side of the cathode pole piece.

[0124] S2, connecting the tab.

[0125] The tab is electrically connected to the third side of the pole piece. The tab includes an anode tab and a cathode tab, wherein the anode tab is arranged on the third side of the anode pole piece and is electrically connected to the anode conductive layer; and the cathode tab is arranged on the third side of the cathode pole piece and is electrically connected to the cathode conductive layer.

[0126] S3, stacking the pole pieces.

[0127] The anode pole pieces and the cathode pole pieces are alternately stacked in the jig, so that the first sides of both the anode pole pieces and the cathode pole pieces are parallel to the first baffle of the jig, and the second sides of both the anode pole pieces and the cathode pole pieces are parallel to the second baffle of the jig.

[0128] The jig comprises a bottom plate for supporting the pole pieces, a first baffle for abutting the first side of the pole piece, and a second baffle for abutting the second side of the pole piece. In this embodiment, the first included angle between the first side and the second side of the pole piece is equal to the second included angle between the first baffle and the second baffle, so that when the first side of the pole piece abuts the first baffle, the second side of the pole piece simultaneously abuts the second baffle, thereby aligning the edges of the first side and the second side of the pole piece, and achieving fast positioning of the first side and the second side of the adjacent anode pole piece and cathode pole piece. In this embodiment, the pole piece is rectangular, and the first included angle and the second included angle are both 90 degrees.

[0129] S4, vibrating the jig.

[0130] In order to reduce the Overhang structure on the first side and the second side of both the cathode pole piece and the anode pole piece to less than 0.6 mm, after the anode pole pieces and the cathode pole pieces are alternately stacked in the jig, the driving device connected to the jig is vibrated to make the jig produce high-frequency low-amplitude mechanical vibration.

[0131] In the embodiment, the third angle between the bottom plate of the clamp and the horizontal plane is consistent with the first angle. In this way, the surface of the bottom plate forms an inclined surface, and the end where the first baffle and the second baffle converge is lower than the end where the first baffle and the second baffle diverge.

[0132] In this way, when the electrode plates are stacked, the vibration clamp plays a guiding role in the movement of the electrode plates, so that the electrode plates move to the end where the first baffle and the second baffle converge under the action of their own gravity, until the first side edge and the second side edge of the electrode plate are attached to the first baffle and the second baffle, respectively.

[0133] In this way, the Overhang size of the first side edge and the second side edge of the two adjacent electrode plates in two directions is less than 0.6 mm. That is, in the direction parallel to the surface of the electrode plate and perpendicular to the first side edge, the distance between the first side edges of the two adjacent electrode plates is less than 0.6 mm, and in the direction parallel to the surface of the electrode plate and perpendicular to the second side edge, the distance between the second side edges of the two adjacent electrode plates is less than 0.6 mm. In this way, the size of the electrode core is reduced in the first side edge and the second side edge directions, greatly improving the energy density of the electrode core.

[0134] In another embodiment of the present application, as shown in FIG. 10, in the direction parallel to the surface of the electrode plate and perpendicular to the first side edge, the size of the first side edge of the anode electrode plate beyond the cathode electrode plate is less than 0.4 mm, and in the direction parallel to the surface of the electrode plate and perpendicular to the fourth side edge, the size of the fourth side edge of the anode electrode plate beyond the cathode electrode plate is between 0.4-0.6 mm. In this way, among the two adjacent electrode plates, the size of the fourth side edge of the anode electrode plate beyond the cathode electrode plate is larger, reducing the risk of lithium precipitation of the anode electrode plate at the fourth side edge, so that the processing precision of the electrode plate has a larger fault tolerance space, thereby reducing the production difficulty.

[0135] The driving device can include a connecting rod mechanism or a cam mechanism, or an ultrasonic vibrator that realizes mechanical vibration by using a piezoelectric effect or a magnetostrictive effect. The driving device is in transmission connection with the clamp, so that the clamp generates continuous vibration with high frequency and low amplitude, and the electrode plate in the clamp moves to the intersection of the first baffle and the second baffle.

[0136] S5, deactivation treatment of the cathode sheet.

[0137] The first side edge of the cathode electrode plate is deactivated to make the size of the anode active material edge of the anode electrode plate located at the first side edge beyond the cathode active material edge of the cathode electrode plate less than 0.6 mm in the direction parallel to the surface of the electrode plate; and the second side edge of the cathode electrode plate is deactivated to make the size of the anode active material layer edge of the anode electrode plate located at the second side edge beyond the cathode active material edge of the adjacent cathode electrode plate less than 0.6 mm in the direction parallel to the surface of the electrode plate.

[0138] The specific manner of the inactivation treatment can adopt a chemical inactivation method, i.e., using a chemical agent to make the part of the cathode active material layer at the first side edge of the cathode electrode sheet lose activity; or can adopt a gluing method, i.e., coating the surface of the part of the cathode active material layer at the first side edge of the cathode electrode sheet with insulating glue, covering the part of the active material layer with the insulating glue so as to make it unable to participate in the charging and discharging process.

[0139] By inactivating the active material layer of the cathode electrode sheet, it is ensured that, in the direction parallel to the electrode sheet, the edge of the active material layer of the anode electrode sheet at the first side edge and the second side edge exceeds the cathode electrode sheet, and the exceeding size is between 0-0.6 mm, thereby avoiding the lithium precipitation phenomenon of the anode electrode sheet.

[0140] S6, packaging the battery cell.

[0141] The stacked electrode sheets are fixed in the packaging shell, and the electrode assembly is connected correspondingly to manufacture a finished battery cell.

[0142] In the production process of the existing laminated battery cell, the placement of the cathode electrode sheet and the anode electrode sheet still needs to be accurately controlled when the electrode sheets are stacked, the rapid stacking of the electrode sheets cannot be realized, the equipment precision requirement is high, the production efficiency is low, and the cost is high.

[0143] However, by using the preparation method of the embodiment, the cathode electrode sheet and the anode electrode sheet are quickly aligned by using the clamp, the precision requirement for dragging and placing the electrode sheet is greatly reduced, the production efficiency of the battery cell is increased, the production cost is reduced in terms of equipment and process difficulty, and the AC-Overhang structure size of at least two edges of the prepared battery cell is reduced, thereby improving the energy density of the battery cell.

[0144] Another preparation method of a battery cell is also disclosed in another embodiment of the present application, as shown in FIG. 13, which includes the following steps:

[0145] S10, manufacturing electrode sheets and separators.

[0146] The active material is coated on the surface of the current collector to form the electrode sheet. The active material can be coated on one side of the current collector or on both sides of the current collector.

[0147] The surface of the anode current collector is coated with an anode material layer to prepare an anode electrode sheet, and the surface of the cathode current collector is coated with a cathode material layer to prepare a cathode electrode sheet.

[0148] Bending stiffness of the electrode sheet wherein b is the length of the first side edge, m1 is the mass of the electrode sheet, K1 is the instability coefficient of the electrode sheet, the value range of K1 is 0.2-0.4, and θ is the included angle between the electrode sheet and the horizontal plane, the value range of θ is between 40-70 degrees. The bending stiffness of the electrode sheet is E1 is the equivalent elastic modulus of the pole piece, t is the thickness of the pole piece (the distance between the first side and the fourth side), and υ1 is the Poisson's ratio of the pole piece. Among them, E1 and υ1 are inherent parameters related to the material of the pole piece, and are fixed values when the material of the pole piece is certain. The pole piece is cut to a predetermined size to make each pole piece have a first side, a second side and a third side, and a first included angle between the first side and the second side.

[0149] The separator is cut into an anode separator consistent with the size of the anode pole piece and a cathode separator consistent with the size of the cathode pole piece, so that the separator has a first side and a second side consistent with the pole piece. The bending stiffness of the separator Where b is the length of the first side, m2 is the mass of the separator, K2 is the instability coefficient of the separator, K2 is in the range of 0.2-4, and θ is the included angle between the pole piece and the horizontal plane, θ is in the range of 40-70 degrees. Where the bending stiffness of the separator E2 is the equivalent elastic modulus of the separator, t is the thickness of the separator (the distance between the first side and the fourth side), and υ2 is the Poisson's ratio corresponding to the material of the separator. Among them, E2 and υ2 are inherent parameters related to the material of the separator, and are fixed values when the material of the separator is certain.

[0150] S20, connecting the tab.

[0151] The tab is electrically connected to the third side of the pole piece. Among them, the anode tab is electrically connected to the anode current collector, and the cathode tab is electrically connected to the cathode current collector.

[0152] S30, pole piece stacking, the anode pole piece, the cathode pole piece are alternately stacked in the above-mentioned clamp, and the separator is placed between the anode pole piece and the cathode pole piece. So that the first side of the plurality of pole pieces and the separator is in contact with the first baffle of the clamp, and the second side of the pole piece and the separator is in contact with the second baffle. Among them, along the direction parallel to the surface of the pole piece and perpendicular to the first side, the distance between the first sides of the adjacent two pole pieces is less than 0.6mm, and along the direction parallel to the surface of the pole piece and perpendicular to the second side, the distance between the second sides of the adjacent two pole pieces is less than 0.6mm.

[0153] S40, vibrating the clamp.

[0154] In order to reduce the AC-Overhang structure on the first side and the second side of both the cathode pole piece and the anode pole piece to less than 0.6mm, when the anode pole piece and the cathode pole piece are alternately stacked in the clamp, the driving device connected with the clamp is also controlled to vibrate the clamp, so that the clamp produces high-frequency low-amplitude mechanical vibration.

[0155] S50, cathode sheet deactivation treatment.

[0156] The first side edge of the cathode tab is deactivated to make the size of the anode active material edge of the anode tab located at the first side edge exceeding the cathode active material edge of the cathode tab less than 0.6 mm in the direction parallel to the tab surface; and the second side edge of the cathode tab is deactivated to make the size of the anode active material layer edge of the anode tab located at the second side edge exceeding the cathode active material edge of the adjacent cathode tab less than 0.6 mm.

[0157] The specific method of the deactivation treatment can be a chemical deactivation method, which makes the part of the cathode active material layer of the cathode tab located at the first side edge lose activity by a chemical agent; or a glue coating method, which coats the part of the cathode active material layer of the cathode tab located at the first side edge with insulating glue to cover the part of the active material layer so that it cannot participate in the charging and discharging process.

[0158] The deactivation treatment of the active material layer of the cathode tab ensures that the edge of the active material layer of the anode tab at the first side edge and the second side edge exceeds the cathode tab in the direction parallel to the tab, and the size of the excess is between 0-0.6 mm.

[0159] S60, packaging the battery cell, and fixing the stacked tabs in a packaging shell.

[0160] The battery cell preparation method disclosed in the embodiment is not limited to the tab with a composite current collector structure, but can also be applied to the scenario where the separator is separated from the tab. The fixture is used to quickly align the cathode tab, the anode tab and the separator, the accuracy requirement for dragging and dropping the tab and the separator is greatly reduced, the production efficiency of the battery cell is increased, the production cost is reduced in terms of equipment and process difficulty, the size of the AC-Overhang of at least three edges of the prepared battery cell is reduced to less than 0.6 mm, and the energy density of the battery cell is improved.

[0161] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; under the idea of the present application, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other changes of different aspects of the present application as described above, which are not provided in detail for simplicity; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement to part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A battery cell, comprising: Multiple electrodes are stacked together. Each electrode has at least a first side, a second side, and a third side. The first side and the second side of each electrode have a first angle. The electrode is an anode electrode or a cathode electrode. The multiple electrodes include at least one anode electrode and at least one cathode electrode. The anode electrode and the cathode electrode are stacked alternately. Each of the electrode plates is provided with an electrode tab, and the electrode tab is provided on the third side; Its features are: In two adjacent electrodes, along a direction parallel to the electrode surface and perpendicular to the first side, the first side of the anode electrode exceeds the cathode electrode by less than 0.6 mm, and along a direction parallel to the electrode surface and perpendicular to the second side, the first side of the anode electrode exceeds the cathode electrode by less than 0.6 mm.

2. The battery cell according to claim 1, characterized in that, The bending stiffness of the electrode Where b is the length of the first side and m1 is the mass of the electrode.

3. The battery cell according to claim 1, characterized in that, In two adjacent electrodes, along a direction parallel to the electrode surface and perpendicular to the first side, the first side of the anode electrode exceeds the cathode electrode by less than 0.4 mm, and along a direction parallel to the electrode surface and perpendicular to the second side, the first side of the anode electrode exceeds the cathode electrode by less than 0.4 mm.

4. The battery cell according to claim 1 or 3, characterized in that, The first side and the second side of each electrode are perpendicular to each other. Each electrode also includes a fourth side parallel to its first side. In two adjacent electrodes, the fourth side of the anode electrode extends beyond the cathode electrode by less than 0.6 mm in a direction parallel to the electrode surface and perpendicular to the fourth side.

5. The battery cell according to claim 3, characterized in that, The first side and the second side of each electrode are perpendicular to each other. Each electrode also includes a fourth side parallel to its first side. In two adjacent electrodes, along a direction parallel to the electrode surface and perpendicular to the fourth side, the fourth side of the anode electrode exceeds the cathode electrode by a size 'a', where 0.4 mm ≤ a < 0.6 mm.

6. The battery cell according to claim 4, characterized in that, In two adjacent electrodes, along a direction parallel to the electrode surface and perpendicular to the third side, the third side of the anode electrode extends beyond the cathode electrode by less than 0.6 mm.

7. The battery cell according to claim 1, characterized in that, Each of the electrodes includes a composite current collector and an active material layer coated on one side of the composite current collector. The composite current collector includes a porous polymer substrate and a conductive layer composited on one side of the porous polymer substrate. The active material layer is coated on the other side of the conductive layer.

8. The battery cell according to claim 1, characterized in that, It also includes a diaphragm disposed between two adjacent electrodes; Each electrode includes a conductive layer and an active material layer coated on the surface of the conductive layer.

9. The battery cell according to claim 8, characterized in that, The flexural stiffness of the diaphragm Where b is the length of the first side and m2 is the mass of the diaphragm.

10. The battery cell according to claim 7 or 8, characterized in that, The battery cell includes two outermost electrode plates located at both ends of the stacking direction, and an intermediate electrode plate located between the two outermost electrode plates. The conductive layer of each intermediate electrode plate is provided with a hole for ion passage.

11. The battery cell according to claim 10, characterized in that, At least one of the outermost electrode layers has an active material layer thickness that is less than the active material layer thickness of the intermediate electrode layer.

12. An apparatus for producing a battery cell as claimed in any one of claims 1-11, comprising a clamp for stacking a plurality of said electrodes, the clamp including a base plate for supporting the plurality of said electrodes, and a first baffle for engaging with a first side of the plurality of said electrodes such that the distance between the first side of two adjacent said electrodes is less than 0.6 mm in a direction parallel to the surface of the electrode and perpendicular to the first side; the clamp further comprising a second baffle for engaging with a second side of the plurality of said electrodes such that the distance between the second side of two adjacent said electrodes is less than 0.6 mm in a direction parallel to the surface of the electrode and perpendicular to the second side; There is a second included angle between the first baffle and the second baffle, and the first included angle is equal to the second included angle.

13. The device according to claim 12, characterized in that, The base plate has a third included angle with respect to the horizontal plane, which is used to make the first side of the plurality of electrodes abut against the first baffle and the second side of the plurality of electrodes abut against the second baffle under the gravity of the electrodes.

14. The device according to claim 13, characterized in that, It also includes a drive device for driving the clamp to vibrate, the drive device being connected to the clamp in a transmission connection.

15. A method for producing a battery cell as described in any one of claims 1-11, characterized in that, include: The preparation of electrodes includes the preparation of anode electrodes and cathode electrodes; The bending stiffness of the electrode Wherein, b is the length of the first side, m1 is the mass of the electrode, θ is the angle between the electrode and the horizontal plane, K1 is the instability coefficient of the electrode, the value of K1 ranges from 0.2 to 0.4, and the value of θ ranges from 40 to 70 degrees; each electrode has at least a first side, a second side, and a third side, and the first angle exists between the first side and the second side; Connect the tab to electrically connect the tab to the third side of the corresponding electrode; The anode and cathode electrodes are stacked alternately in a fixture as described in any one of claims 12-14, such that the first and second sides of the plurality of electrodes are respectively in contact with the first and second baffles of the fixture; the bottom plate of the fixture has a third angle with the horizontal plane, the size of the third angle being the same as θ, and the end where the first and second baffles converge is lower than the end where they diverge; The battery cell is encapsulated by fixing the stacked electrodes inside the encapsulation shell.

16. The method according to claim 15, characterized in that, Along a direction parallel to the surface of the electrode and perpendicular to the first side, the distance between the first side of two adjacent electrodes is less than 0.6 mm; Along a direction parallel to the surface of the electrode and perpendicular to the second side, the distance between the second sides of two adjacent electrodes is less than 0.6 mm.

17. The method according to claim 15, characterized in that, Along a direction parallel to the surface of the electrode and perpendicular to the first side, the distance between the first sides of two adjacent electrodes is less than 0.4 mm; Along a direction parallel to the surface of the electrode and perpendicular to the second side, the distance between the second sides of two adjacent electrodes is less than 0.4 mm.

18. The method according to claim 15, characterized in that, The preparation of the electrode includes: A composite current collector is prepared by bonding a conductive layer to the surface of a porous polymer substrate to form a composite current collector; wherein the composite current collector includes an anodic composite current collector and a cathode composite current collector, the anodic composite current collector includes an anodic porous polymer substrate and an anodic conductive layer, and the cathode composite current collector includes a cathode porous polymer substrate and a cathode conductive layer. An active material layer is coated on the surface of the conductive layer opposite to the porous polymer substrate. Specifically, an anodic active material layer is coated on the side of the anodic conductive layer opposite to the anodic porous polymer substrate, and a cathode active material layer is coated on the side of the cathode conductive layer opposite to the cathode porous polymer substrate.

19. The method according to claim 15, characterized in that, The electrode preparation step further includes: preparing a separator, the separator including an anode separator with the same size as the anode electrode and a cathode separator with the same size as the cathode electrode, the separator having a first side and a second side consistent with the electrode; The stiffness of the diaphragm Where b is the length of the first side, m2 is the mass of the diaphragm, K2 is the instability coefficient of the diaphragm, the value of K2 is in the range of 0.2-0.4, and θ is the angle between the electrode and the horizontal plane, the value of θ is in the range of 40-70 degrees. The electrode stacking step further includes: placing the diaphragm between the anode electrode and the cathode electrode, so that the first side of the plurality of electrodes and the diaphragm and the first baffle of the clamp are in contact with each other, while the second side of the electrodes and the diaphragm are in contact with the second baffle.

20. The method according to claim 15, characterized in that, The process before encapsulating the battery cell also includes cathode electrode deactivation treatment: The first side of the cathode electrode is deactivated so that, in the direction parallel to the electrode surface, the edge of the anode active material layer of the anode electrode located on the first side exceeds the edge of the cathode active material layer of the cathode electrode by less than 0.6 mm. The second side of the cathode electrode is deactivated so that, in the direction parallel to the electrode surface, the edge of the anodic active material layer of the anode electrode located on the second side exceeds the edge of the cathode active material layer of the cathode electrode by less than 0.6 mm.

21. The method according to claim 18, characterized in that, Holes are formed on the surface of the conductive layer to allow ions to pass through.

22. The method according to claim 18, characterized in that, The battery cell includes two outermost electrode plates located at both ends of the stacking direction, and an intermediate electrode plate located between the two outermost electrode plates. At least one of the outermost electrode coatings has an active material layer thickness that is less than the active material layer of the intermediate electrode.

23. The method according to claim 15, characterized in that, The process before packaging also includes: The vibration fixture is controlled to generate mechanical vibration, which is used to make the first side and the second side of the plurality of electrodes fit against the first baffle and the second baffle respectively under the action of gravity.

Images