Cathode pole piece, battery and electric device

Abstract

The utility model belongs to the technical field of battery production and manufacturing, and particularly relates to a cathode pole piece which comprises a current collector and an active material layer coated on the current collector, the current collector is provided with an empty foil area which is not coated with the active material layer, and the empty foil area is used for placing a tab. The tab is provided with a tab bottom end corresponding to the empty foil area, the tab bottom end is connected with the empty foil area through a hot-melt fixing adhesive, the tab and the hot-melt fixing adhesive are partially overlapped, the hot-melt fixing adhesive is of a trapezoidal structure, the projection area of the hot-melt fixing adhesive in the thickness direction of the cathode pole piece is S1, and the projection area of the hot-melt fixing adhesive in the thickness direction of the cathode pole piece is S2. The projection area of the tab in the thickness direction is S2, S1 and S2 meet the relational expression that S1 = a * S2, and a is larger than or equal to 0.03 and smaller than or equal to 0.09. The hot melting fixing glue can prevent the bottom ends of the tabs from cracking, so that the safety performance is improved. In addition, the utility model also discloses a battery comprising the cathode pole piece and an electric device.

Description

Technical Field

[0001] The utility model belongs to the technical field of battery production and manufacturing, and specifically relates to a cathode electrode piece, a battery and an electrical device. Background Art

[0002] Nowadays, with the development of modern society and the enhancement of people's environmental awareness, more and more devices choose lithium-ion batteries as power sources, such as mobile phones, laptops, power tools and electric vehicles, which provides a broad space for the application and development of lithium-ion batteries.

[0003] As the energy density requirements of lithium-ion power batteries continue to increase, it has become a common practice to reduce the thickness of foil and leave more physical space for active materials to increase the energy density of batteries. The increasingly thin foil thickness not only requires higher welding technology for the battery cell tabs, but also increases the risk of damage and breakage of the tab foil inside the battery during module assembly and application. After the power battery has been circulating for a period of time, it is easy to cause cracks at the bottom of the cathode tab due to the influence of the tab burrs and expansion tension, and further extend to the cracks on both sides of the tab, affecting battery performance and causing serious safety risks. To this end, it is urgent to propose a new technical solution to solve the above problems. Utility Model Content

[0004] One of the purposes of the utility model is to provide a cathode pole piece in view of the deficiencies of the prior art, which prevents the bottom end of the pole ear from cracking and increases the safety performance of the cathode pole piece by arranging hot-melt fixing glue at the bottom end of the pole ear.

[0005] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0006] A cathode electrode sheet comprises a current collector and an active material layer coated on the current collector, the current collector is provided with an empty foil area not coated with the active material layer, the empty foil area is used to place a pole ear, the pole ear has a pole ear bottom end corresponding to the empty foil area, the pole ear bottom end is connected to the empty foil area by a hot-melt fixing glue, the pole ear and the hot-melt fixing glue are partially overlapped, the hot-melt fixing glue is arranged in a trapezoidal structure, the projection area of ​​the hot-melt fixing glue in the thickness direction of the cathode electrode sheet is S1, the projection area of ​​the pole ear in the thickness direction is S2, and S1 and S2 satisfy the relationship: S1=a*S2, 0.03≤a≤0.09.

[0007] In actual applications, the cathode electrode heats up due to charging and discharging, and the hot-melt fixing glue melts, so that the electrode ear and the current collector adhere to each other, increasing the connection strength between the electrode ear and the current collector, avoiding the cracking of the bottom end of the electrode ear and then extending to the entire electrode ear, thereby improving safety performance.

[0008] As an improvement of the cathode electrode piece described in the utility model, the hot melt fixing adhesive has an upper bottom edge, and the length of the upper bottom edge in the length direction of the cathode electrode piece is the same as the length of the bottom end of the electrode ear in the length direction.

[0009] As an improvement of the cathode electrode sheet described in the utility model, the hot-melt fixing adhesive has a lower bottom edge parallel to the upper bottom edge, and in the width direction of the cathode electrode sheet, the bottom end of the pole ear is located between the upper bottom edge and the lower bottom edge, the length of the upper bottom edge in the length direction is L1, and the length of the lower bottom edge in the length direction is L2, and L1 and L2 satisfy the relationship: L2=L1+b, 2mm≤b≤4mm.

[0010] As an improvement of the cathode electrode plate described in the utility model, the hot melt fixing adhesive is set to an isosceles trapezoidal structure, the distance between the lower bottom corner and the corresponding upper bottom edge is L3, and L3 satisfies the relationship: 1mm≤L3≤2mm.

[0011] As an improvement of the cathode electrode sheet described in the utility model, the distance between the upper bottom edge and the lower bottom edge in the width direction is set to 6mm-8mm.

[0012] As an improvement of the cathode electrode sheet of the utility model, the distance between the lower bottom edge and the bottom end of the electrode ear in the width direction is set to 2mm-4mm.

[0013] As an improvement of the cathode electrode sheet described in the utility model, the thickness of the hot-melt fixing adhesive in the thickness direction is 0.1 mm-0.3 mm.

[0014] In the utility model, the length direction, the width direction and the thickness direction are equivalent to the Y-axis direction, the X-axis direction and the Z-axis direction in the rectangular coordinate system, and the above three directions are perpendicular to each other; the parameter limitation of the hot-melt fixing glue can further ensure the realization of the function of preventing the bottom end of the pole ear from cracking without affecting the thickness of the cathode electrode sheet and the electrical properties of the pole ear.

[0015] As an improvement of the cathode electrode sheet described in the utility model, the hot melt fixing glue includes a superimposed substrate layer and an adhesive layer, the material of the substrate layer is set to one or more of thermoplastic polyester, polyethylene, polypropylene and polyvinyl chloride, and the material of the adhesive layer is set to one or more of acrylic resin, polycarbonate, polyurethane and rubber. In actual application, the substrate layer is arranged close to the electrode ear, and the adhesive layer is arranged close to the current collector, so as to further ensure its hot melt property and increase the connection strength between the electrode ear and the current collector.

[0016] The second object of the utility model is to provide a battery, comprising an anode electrode sheet, the cathode electrode sheet as described above, and a diaphragm, wherein the diaphragm is located between the anode electrode sheet and the cathode electrode sheet.

[0017] The second purpose of the utility model is to provide an electrical device, comprising the battery as described above.

[0018] The beneficial effect of the utility model lies in that the cathode electrode sheet of the utility model comprises a current collector and an active material layer coated on the current collector, the current collector is provided with an empty foil area which is not coated with the active material layer, the empty foil area is used to place the pole ear, the pole ear has a pole ear bottom end corresponding to the empty foil area, the pole ear bottom end is connected to the empty foil area by a hot-melt fixing glue, the pole ear partially overlaps with the hot-melt fixing glue, the hot-melt fixing glue is arranged in a trapezoidal structure, the projection area of ​​the hot-melt fixing glue in the thickness direction of the cathode electrode sheet is S1, the projection area of ​​the pole ear in the thickness direction is S2, and S1 and S2 satisfy the relationship: S1=a*S2, 0.03≤a≤0.09. The utility model arranges hot-melt fixing glue at the bottom end of the pole ear. In actual application, when the battery composed of the negative electrode plate of the utility model is subjected to charge and discharge cycles, the temperature rise increases, causing the hot-melt fixing glue to melt, thereby enhancing the adhesion between the bottom end of the pole ear and the current collector. Moreover, since the hot-melt fixing glue is arranged in a trapezoidal structure, the melted hot-melt fixing glue plays a role of surrounding and fixing the bottom end of the pole ear, thereby avoiding the situation where the bottom end of the pole ear cracks and then extends to the entire pole ear, thereby improving the safety performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The features, advantages and technical effects of exemplary embodiments of the present invention will be described below with reference to the accompanying drawings.

[0020] Figure 1 It is a structural schematic diagram of the utility model.

[0021] Figure 2 This is one of the structural schematic diagrams of the hot melt fixing adhesive in the utility model.

[0022] Figure 3 This is the second structural schematic diagram of the hot melt fixing adhesive in the utility model.

[0023] The reference numerals are described as follows:

[0024] 1-current collector;

[0025] 2-active material layer;

[0026] 3-ear; 31-bottom of ear;

[0027] 4-hot melt fixing glue; 41-upper bottom edge; 42-lower bottom edge; 43-base material layer; 44-adhesive layer;

[0028] Y-length direction; X-width direction; Z-thickness direction. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0030] Unless otherwise defined, all technical and scientific terms used in this application have the same meanings as those commonly understood by technicians in the technical field to which this application belongs; the terms used in the specification of this application are only for the purpose of describing specific implementation methods and are not intended to limit this application; the terms "including" and "having" in the specification and claims of this application and the above-mentioned figure descriptions and any variations thereof are intended to cover non-exclusive inclusions.

[0031] Reference to "embodiment" in this application means that a particular feature, structure or characteristic described in conjunction with the embodiment may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments.

[0032] In the embodiments of the present application, the same reference numerals represent the same components, and for the sake of brevity, detailed descriptions of the same components are omitted in different embodiments. It should be understood that the thickness, length, width and other dimensions of various components in the embodiments of the present application shown in the drawings, as well as the overall thickness, length, width and other dimensions of the integrated device are only exemplary descriptions and should not constitute any limitation to the present application.

[0033] The battery includes an electrode assembly and an electrolyte. The electrode assembly is composed of a positive electrode sheet, a negative electrode sheet and a separator. The battery mainly relies on the movement of metal ions between the positive electrode sheet and the negative electrode sheet to work. The positive electrode sheet includes a positive electrode collector and a positive electrode active material layer. The positive electrode active material layer is coated on the surface of the positive electrode collector. The positive electrode collector not coated with the positive electrode active material layer protrudes from the positive electrode collector coated with the positive electrode active material layer. The positive electrode collector not coated with the positive electrode active material layer serves as the positive electrode tab. Taking lithium-ion batteries as an example, the material of the positive electrode collector can be aluminum, and the positive electrode active material can be lithium cobalt oxide, lithium iron phosphate, ternary lithium or lithium manganese oxide. The negative electrode sheet includes a negative electrode collector and a negative electrode active material layer. The negative electrode active material layer is coated on the surface of the negative electrode collector. The negative electrode collector not coated with the negative electrode active material layer protrudes from the negative electrode collector coated with the negative electrode active material layer. The negative electrode collector not coated with the negative electrode active material layer serves as the negative electrode tab. The material of the negative electrode current collector may be copper, and the negative electrode active material may be carbon or silicon, etc. In order to ensure that a large current can pass without melting, the number of positive electrode tabs is multiple and stacked together, and the number of negative electrode tabs is multiple and stacked together. The material of the isolation film may be PP (polypropylene) or PE (polyethylene), etc. In addition, the electrode assembly may be a winding structure or a laminated structure, and the embodiments of the present application are not limited thereto.

[0034] The development of battery technology must take into account many design factors at the same time, such as energy density, cycle life, discharge capacity, charge and discharge rate and other performance parameters. In addition, battery safety must also be considered.

[0035] For battery cells, the main safety hazard comes from the charging and discharging process. After a period of charge and discharge cycles, the pole piece will expand and shift. Since the pole tab is set in the empty foil area of ​​the pole piece, it is easy to break at the bottom of the pole tab due to the influence of burrs and expansion pressure. In addition, most existing pole pieces use thinner current collectors for higher energy density, which makes the pole tab more likely to break during module assembly and actual application, reducing the safety performance of the battery. In view of this, this embodiment increases the connection strength between the bottom of the pole tab and the current collector by setting hot melt fixing glue at the bottom of the pole tab, strengthens the protection of the bottom of the pole tab, prevents cracking, and improves safety performance.

[0036] The following is combined with Figures 1 to 3 The utility model is further described in detail with specific implementation modes, but is not intended to limit the utility model.

[0037] A cathode electrode sheet comprises a current collector 1 and an active material layer 2 coated on the current collector 1, the current collector 1 is provided with a hollow foil area which is not coated with the active material layer 2, the hollow foil area is used to place a pole ear 3, the pole ear 3 has a pole ear bottom end 31 corresponding to the hollow foil area, the pole ear bottom end 31 is connected to the hollow foil area through a hot-melt fixing adhesive 4, the pole ear 3 partially overlaps with the hot-melt fixing adhesive 4, and the hot-melt fixing adhesive 4 is arranged in a trapezoidal structure.

[0038] In actual applications, during the charge and discharge cycle of the battery, the battery temperature rises and the hot melt fixing glue 4 melts, which can increase the bonding force between the bottom end 31 of the pole lug and the current collector 1. In addition, since the hot melt fixing glue 4 has a trapezoidal structure, it can wrap and fix the bottom end 31 of the pole lug, thereby preventing the bottom end 31 of the pole lug from cracking due to burrs and expansion and extrusion, thereby improving safety performance.

[0039] In the present invention, the cross-section of the hot-melt fixing adhesive 4 is an isosceles trapezoid, which can better wrap and fix the bottom end 31 of the tab. It is understandable that in some other technical solutions, the hot-melt fixing adhesive 4 can be set to other types of trapezoidal structures and can be adjusted according to actual conditions.

[0040] Preferably, the projection area of ​​the hot-melt fixing adhesive 4 in the thickness direction Z of the cathode electrode is S1, and the projection area of ​​the electrode tab 3 in the thickness direction Z is S2. S1 and S2 satisfy the relationship: S1=a*S2, 0.03≤a≤0.09, to prevent the area of ​​the hot-melt fixing adhesive 4 from being too large and affecting the power transmission performance of the electrode tab 3.

[0041] Preferably, the hot melt fixing glue 4 has an upper bottom edge 41, and the length of the upper bottom edge 41 in the length direction Y of the cathode electrode is the same as the length of the bottom end 31 of the pole lug in the length direction Y. The hot melt fixing glue 4 has a lower bottom edge 42 parallel to the upper bottom edge 41. In the width direction X, the bottom end 31 of the pole lug is located between the upper bottom edge 41 and the lower bottom plate 42. The length of the upper bottom edge 41 in the length direction Y is L1, and the length of the lower bottom edge 42 in the length direction Y is L2. L1 and L2 satisfy the relationship: L2=L1+b, 2mm≤b≤4mm, ensuring that the length of the lower bottom edge 42 of the hot melt fixing glue 4 is greater than the length of the pole lug 3, further improving the wrapping and fixing effect of the hot melt fixing glue 4, and preventing the bottom end 31 of the pole lug from cracking; in this embodiment, the pole lug extreme 31 is set to 4mm, and the length of the lower bottom edge 42 is 6mm-8mm, which can be adjusted accordingly according to actual conditions.

[0042] Preferably, the distance between the corner of the lower bottom edge 42 and the edge of the corresponding upper bottom edge 41 is L3, and L3 satisfies the relationship: 1mm≤L3≤2mm; the distance between the upper bottom edge 41 and the lower bottom edge 42 in the width direction X of the cathode electrode sheet is set to 6mm-8mm; the distance between the lower bottom edge 42 and the bottom end 31 of the pole ear in the width direction X of the cathode electrode sheet is set to 2mm-4mm; the thickness of the hot melt fixing glue 4 in the thickness direction Z is 0.1mm-0.3mm; the length direction Y, the width direction X and the thickness direction Z are equivalent to the Y-axis direction, the X-axis direction and the Z-axis direction in the rectangular coordinate system, and the above three directions are perpendicular to each other; the setting of the above parameters further prevents the hot melt fixing glue 4 from affecting the electrical properties of the pole ear 3 and the current collector 1.

[0043] Preferably, the hot melt fixing glue 4 includes a superimposed substrate layer 43 and an adhesive layer 44, the material of the substrate layer 43 is set to one or more of thermoplastic polyester, polyethylene, polypropylene and polyvinyl chloride, and the material of the adhesive layer 44 is set to one or more of acrylic resin, polycarbonate, polyurethane and rubber. In actual application, the substrate layer 43 is arranged close to the pole ear 3, and the adhesive layer 44 is arranged close to the current collector 1, so as to further ensure its hot melt property and increase the connection strength between the pole ear 3 and the current collector 1.

[0044] Battery

[0045] A battery comprises an anode electrode sheet, a cathode electrode sheet as described above and a separator, wherein the separator is located between the anode electrode sheet and the cathode electrode sheet, and the battery can be a lithium ion battery, a sodium ion battery, a magnesium ion battery, etc.

[0046] Electrical devices

[0047] An electrical device, comprising the above-mentioned battery, wherein the electrical device can be a vehicle, a mobile phone, a portable device, a laptop computer, a ship, a spacecraft, an electric toy, an electric tool, etc. The vehicle can be a fuel vehicle, a gas vehicle or a new energy vehicle, and the new energy vehicle can be a pure electric vehicle, a hybrid vehicle or an extended-range vehicle, etc.; the spacecraft includes an airplane, a rocket, a space shuttle and a spacecraft, etc.; the electric toy includes a fixed or mobile electric toy, such as a game console, an electric car toy, an electric ship toy and an electric airplane toy, etc.; the electric tool includes a metal cutting electric tool, a grinding electric tool, an assembly electric tool and an electric tool for railways, such as an electric drill, an electric grinder, an electric wrench, an electric screwdriver, an electric hammer, an impact drill, a concrete vibrator and an electric planer, etc. The embodiments of the present application do not impose any special restrictions on the above-mentioned electrical devices.

[0048] According to the disclosure and teaching of the above description, the technicians in the field of the utility model can also change and modify the above implementation. Therefore, the utility model is not limited to the above specific implementation, and any obvious improvement, replacement or modification made by the technicians in this field on the basis of the utility model belongs to the protection scope of the utility model. In addition, although some specific terms are used in this specification, these terms are only for the convenience of explanation and do not constitute any limitation to the utility model.

Claims

1. A cathode electrode sheet, comprising a current collector (1) and an active material layer (2) coated on the current collector (1), wherein the current collector (1) is provided with an empty foil area not coated with the active material layer (2), and the empty foil area is used to place a tab (3), characterized in that: The pole lug (3) has a pole lug bottom end (31) corresponding to the empty foil area, the pole lug bottom end (31) is connected to the empty foil area via a hot melt fixing glue (4), the pole lug (3) and the hot melt fixing glue (4) partially overlap, the hot melt fixing glue (4) is arranged in a trapezoidal structure, the projection area of ​​the hot melt fixing glue (4) in the thickness direction (Z) of the cathode electrode sheet is S1, the projection area of ​​the pole lug (3) in the thickness direction (Z) is S2, and S1 and S2 satisfy the relationship: S1 = a*S2, 0.03≤a≤0.

09.

2. The cathode electrode according to claim 1, characterized in that: The hot melt fixing adhesive (4) has an upper bottom edge (41), and the length of the upper bottom edge (41) in the length direction (Y) of the cathode electrode sheet is the same as the length of the bottom end (31) of the electrode tab in the length direction (Y).

3. The cathode electrode according to claim 2, characterized in that: The hot-melt fixing adhesive (4) has a lower bottom edge (42) parallel to the upper bottom edge (41); in the width direction (X) of the cathode electrode sheet, the bottom end (31) of the electrode ear is located between the upper bottom edge (41) and the lower bottom edge (42); the length of the upper bottom edge (41) in the length direction (Y) is L1, and the length of the lower bottom edge (42) in the length direction (Y) is L2; ​​L1 and L2 satisfy the relationship: L2=L1+b, 2mm≤b≤4mm.

4. The cathode electrode according to claim 3, characterized in that: The hot melt fixing adhesive (4) is configured as an isosceles trapezoidal structure, and the distance between the corner of the lower base (42) and the corresponding edge of the upper base (41) is L3, and L3 satisfies the relationship: 1mm≤L3≤2mm.

5. The cathode electrode according to claim 3, characterized in that: The distance between the upper bottom edge (41) and the lower bottom edge (42) in the width direction (X) is set to 6 mm-8 mm.

6. The cathode electrode according to claim 3, characterized in that: The distance between the lower bottom edge (42) and the bottom end (31) of the tab in the width direction (X) is set to 2 mm-4 mm.

7. The cathode electrode according to claim 1, characterized in that: The thickness of the hot-melt fixing adhesive (4) in the thickness direction (Z) is 0.1 mm-0.3 mm.

8. The cathode electrode according to claim 1, characterized in that: The hot-melt fixing adhesive (4) comprises a superimposed substrate layer (43) and an adhesive layer (44), wherein the substrate layer (43) is arranged close to the electrode tab (3), and the adhesive layer (44) is arranged close to the current collector (1).

9. A battery, characterized in that: It comprises an anode electrode piece, a cathode electrode piece as claimed in any one of claims 1 to 8, and a separator, wherein the separator is located between the anode electrode piece and the cathode electrode piece.

10. An electrical device, characterized in that: Comprising the battery as claimed in claim 9.

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