Pole piece, battery and electric equipment

Abstract

The utility model discloses a pole piece, a battery and electric equipment. The pole piece comprises a current collector, an active material layer and a tab, wherein the current collector is made of conductive foil; the active material layer is arranged on at least one side of the current collector along the thickness direction, the active material layer is provided with a first tab groove, and the first tab groove penetrates through the current collector to expose the conductive foil; the tab is arranged in the first tab groove and is connected with the current collector; wherein the first tab groove is further filled with an insulating part, the insulating part wraps the tab, and the insulating part does not protrude out of the active substance layer. According to the pole piece, the diaphragm can be tightly attached to the pole piece, the conduction path of lithium ions is remarkably reduced, the impedance of the battery is reduced, and the lithium separation risk is reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of new energy batteries, and in particular to a pole piece, a battery and an electrical device. Background Art

[0002] In existing battery structures, electrode sheets are typically provided with tab slots for welding the tabs. After the tabs are installed in the slots, insulating tape is applied to protect the tabs. However, due to the thickness of the insulating tape, it protrudes from the surface of the electrode sheet after being applied, making the thickness of the electrode sheet where the tabs are located greater than that of other areas.

[0003] During the winding process of the electrode, the raised part abuts against the diaphragm and deforms the diaphragm, causing the lithium ion conduction interface path to become longer, the impedance to increase, and it is easy to cause interface defects such as bubbles and pores, causing lithium deposition during battery charging. Utility Model Content

[0004] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention proposes a pole piece that can make the separator and the pole piece fit more tightly, significantly reducing the conduction path of lithium ions, lowering the impedance of the battery and reducing the risk of lithium plating.

[0005] The utility model also provides a battery having the above-mentioned electrode piece.

[0006] The utility model also provides an electrical device having the battery.

[0007] The pole piece according to the first embodiment of the present invention includes:

[0008] a current collector, wherein the current collector is made of a conductive foil;

[0009] an active material layer, the active material layer being disposed on at least one side of the current collector along its thickness direction, the active material layer being provided with a first tab groove, the first tab groove penetrating the current collector to expose the conductive foil;

[0010] a tab, the tab being disposed in the first tab slot and connected to the current collector;

[0011] The first tab groove is further filled with an insulating member, the insulating member covers the tab, and the insulating member is not protruding from the active material layer.

[0012] The pole piece according to the embodiment of the utility model has at least the following beneficial effects:

[0013] In the prior art, since the insulating tape needs to be attached to the active material layer, the insulating tape is bound to protrude from the surface of the active material layer. In the present application, since the insulating member can be directly filled in the first pole ear groove, the thickness of the pole piece, the thickness of the active material layer and the thickness of the insulating member can be reasonably designed so that the insulating member does not protrude from the active material layer to ensure that there is no raised part on the pole piece to abut against the diaphragm when the pole piece is wound, thereby reducing the deformation degree of the diaphragm, making the interface gap at the pole ear lower, and the diaphragm and the pole piece fit more tightly, thereby significantly reducing the conduction path of lithium ions, reducing the impedance of the battery, reducing the risk of lithium plating, and improving the overall performance of the battery compared to the battery in the prior art.

[0014] According to some embodiments of the present invention, the insulating member is flush with the surface of the active material layer.

[0015] According to some embodiments of the present invention, the size of the pole tab is smaller than the size of the first pole tab slot, so that an exposed foil space is formed between the pole tab and the slot wall of the first pole tab slot, part of the insulating member fills the exposed foil space, and part of the insulating member covers the pole tab.

[0016] According to some embodiments of the present invention, the portion of the insulating member covering the electrode tab is set as a first coating portion, and the thickness of the first coating portion is 5 μm to 20 μm.

[0017] According to some embodiments of the present invention, the portion of the insulating member filling the exposed foil space is defined as a second coating portion, and a thickness of the second coating portion is greater than a thickness of the first coating portion.

[0018] According to some embodiments of the present invention, the sum of the thickness of the first coating portion and the thickness of the tab is equal to the thickness of the active material layer.

[0019] According to some embodiments of the present invention, the thermal conductivity of the insulating member is greater than or equal to 15 W / (m·K).

[0020] According to some embodiments of the present invention, the active material layer is provided on both sides of the current collector along its thickness direction, one of the active material layers is provided with the first pole tab groove, and the other active material layer is provided with the second pole tab groove, the first pole tab groove and the second pole tab groove are arranged opposite to each other, and the second pole tab groove is filled with the insulating member.

[0021] The battery according to the second embodiment of the present invention includes the pole piece described in any one of the above embodiments.

[0022] The electrical equipment according to the third embodiment of the present utility model includes the battery described in the above embodiment.

[0023] Additional aspects and advantages of the present invention will be given in part in the following description and will become apparent from the following description or learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The present invention will be further described below with reference to the accompanying drawings and embodiments, wherein:

[0025] Figure 1 It is the insulation structure of the pole piece at the pole ear in the prior art;

[0026] Figure 2 This is the insulation structure of the pole piece at the pole ear of an embodiment of the present utility model.

[0027] Reference numerals:

[0028] Current collector 100;

[0029] Active material layer 200; first electrode tab groove 210; second electrode tab groove 220;

[0030] Tab 300;

[0031] Insulating member 400; first coating portion 410; second coating portion 420;

[0032] Insulation tape 500. DETAILED DESCRIPTION

[0033] The following describes embodiments of the present invention in detail. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended only to explain the present invention and are not to be construed as limiting the present invention.

[0034] In the description of the present invention, it should be understood that descriptions involving orientations, such as up, down, front, back, left, right, etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they cannot be understood as limitations on the present invention.

[0035] In the description of this utility model, "several" means more than one, "plurality" means more than two, "greater than," "less than," and "exceed" are understood to exclude the number itself, while "above," "below," and "within" are understood to include the number itself. The use of the terms "first" and "second" is solely for the purpose of distinguishing technical features and is not to be construed as indicating or implying relative importance, implicitly specifying the number of the indicated technical features, or implicitly specifying the order of the indicated technical features.

[0036] In the description of the present invention, unless otherwise clearly defined, terms such as setting, installing, and connecting should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in the present invention based on the specific content of the technical solution.

[0037] In the description of the present invention, reference to terms such as "one embodiment," "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the exemplary expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0038] In the existing battery structure, such as Figure 1 As shown, the electrode sheet is typically provided with a tab slot for welding the tab. After the tab is installed in the tab slot, insulating tape 500 is applied to insulate and protect the tab. However, since the insulating tape 500 has a certain thickness, it protrudes from the surface of the electrode sheet after being attached to the electrode sheet, making the thickness of the electrode sheet where the tab is located greater than that of other areas.

[0039] During the winding process of the electrode, the raised part abuts against the diaphragm and deforms the diaphragm, causing the lithium ion conduction interface path to become longer, the impedance to increase, and it is easy to cause interface defects such as bubbles and pores, causing lithium deposition during battery charging.

[0040] To solve the above problems, Figure 2 As shown, the first embodiment of the present application proposes a pole piece, which includes a current collector 100, an active material layer 200 and a pole ear 300. The current collector 100 is made of a conductive foil. It should be noted that the conductive foil can be copper foil, aluminum foil, etc., or a composite foil with good conductive properties, so as to play a role in transmitting current during the battery charging and discharging process.

[0041] The active material layer 200 is disposed on at least one side of the current collector 100 along its thickness. Pole sheets include single-sided sheets and double-sided sheets. Single-sided sheets are coated with the active material layer 200 on one side of the current collector 100, while double-sided sheets are coated with the active material layer 200 on both sides of the current collector 100. The active material layer 200 is formed by coating the active material coating on the current collector 100. During the battery's charge and discharge processes, it undergoes electrochemical reactions and releases or inserts lithium ions. A first tab groove 210 is provided along the width edge of the active material layer 200. The first tab groove 210 is used to accommodate the tab 300. Specifically, the first tab groove 210 extends along the thickness of the current collector 100 until it penetrates the current collector 100, exposing the conductive foil at the bottom of the first tab groove 210. This allows the tab 300 to be directly connected to the current collector 100, allowing current to be concentratedly input or output from the tab 300.

[0042] The tab 300 is disposed in the first tab groove 210 and connected to the current collector 100. The tab 300 can be fixed to the current collector 100 by welding, bonding, or other connection methods. It is understood that the thickness of the tab 300 is less than the thickness of the active material layer 200. Therefore, when the tab 300 is disposed in the first tab groove 210, the surface of the tab 300 away from the current collector 100 is lower than the surface of the active material layer 200.

[0043] The pole piece also includes an insulating member 400, which is filled in the first pole ear groove 210 where the pole ear 300 is provided, and the insulating member 400 is wrapped around the pole ear 300. The insulating member 400 is formed by mixing an insulating material and an adhesive, and has good insulation properties. It is wrapped around the pole ear 300 to prevent the pole ear 300 from contacting the adjacent pole piece and causing a short circuit.

[0044] In the prior art, since the insulating tape 500 needs to be attached to the active material layer 200, the insulating tape 500 is bound to protrude from the surface of the active material layer 200. In the present application, since the insulating member 400 can be directly filled in the first pole ear groove 210, by reasonably designing the thickness of the pole piece, the thickness of the active material layer 200 and the thickness of the insulating member 400, the insulating member 400 can be prevented from protruding from the active material layer 200 to ensure that there is no raised part on the pole piece to abut against the diaphragm when the pole piece is wound, thereby reducing the degree of deformation of the diaphragm, making the interface gap at the pole ear 300 lower, and the diaphragm and the pole piece fit more tightly, thereby significantly reducing the conduction path of lithium ions, reducing the impedance of the battery, reducing the risk of lithium plating, and improving the overall performance of the battery compared to the battery in the prior art.

[0045] In some embodiments, the insulating member 400 is flush with the surface of the active material layer 200, that is, after the electrode tab 300 is connected to the first electrode tab groove 210, the insulating member 400 fills the remaining space in the first electrode tab groove 210 and makes the surface of the insulating member 400 flush with the surface of the active material layer 200 to improve the flatness of the electrode piece.

[0046] In some embodiments, the tab 300 is smaller than the first tab slot 210. That is, along the thickness direction of the current collector 100, the entire projection of the tab 300 onto the current collector 100 falls within the first tab slot 210. A gap exists between the side of the tab 300 and the wall of the first tab slot 210, allowing a portion of the conductive foil to remain exposed. For ease of description, the gap between the tab 300 and the wall of the first tab slot 210 is referred to as the "exposed foil space." Prolonged exposure of the foil to the electrolyte can cause corrosion. To this end, a portion of the insulating member 400 fills the exposed foil space, while another portion of the insulating member 400 covers the tab 300.

[0047] Furthermore, for the convenience of subsequent description, the portion of the insulating member 400 covering the tab 300 is designated as the first coating portion 410, and the portion of the insulating member 400 filling the exposed foil space is designated as the second coating portion 420. The thickness of the first coating portion 410 is 5 μm to 20 μm. It is understood that if the thickness of the first coating portion 410 is too thin, it will not provide insulation protection. If the thickness of the first coating portion 410 is too thick, then if the thickness of the tab 300 and the thickness of the active material layer 200 are constant, the first coating portion 410 will protrude from the surface of the active material layer 200. Preferably, the sum of the thickness of the first coating portion 410 and the thickness of the tab 300 is equal to the thickness of the active material layer 200.

[0048] It is understood that the thickness of the second coating portion 420 is greater than the thickness of the first coating portion 410. The insulating member 400 may be a slurry that is filled in the first tab groove 210 and then solidified in the first tab groove 210 by a process such as drying.

[0049] In some embodiments, it should be noted that the insulating member 400 also has good thermal conductivity. The insulating member 400 is made of a high thermal conductivity insulating material and an adhesive. The high thermal conductivity insulating material includes one or more of boehmite, BeO (beryllium oxide), MgO (magnesium oxide), Al2O3 (aluminum oxide), NiO (nickel oxide), AlN (aluminum nitride), Si3N4 (silicon nitride), and BN (boron nitride); the adhesive includes one or more of styrene-butadiene rubber, polyacrylate, and polyvinylidene fluoride.

[0050] It should be noted that high thermal conductivity insulating materials, in addition to having insulating properties, also have better thermal conductivity compared to ordinary insulating materials (such as plastics). Their thermal conductivity coefficient is greater than or equal to 15W / (m·K). During the battery charging and discharging process, they can quickly absorb and transfer the heat generated at the pole tab 300 to dissipate heat from the pole tab 300, thereby improving the problem of large temperature rise at the pole tab 300 during the charging and discharging process.

[0051] In some embodiments, active material layers 200 are provided on both sides of the current collector 100 along its thickness. A first tab groove 210 is provided on one active material layer 200, and a second tab groove 220 is provided on the other active material layer 200. It should be noted that after the electrode sheet undergoes the coating process, the active material is evenly distributed on the surface of the current collector 100. Laser cleaning is then performed to form the first tab groove 210 and the second tab groove 220 on each side of the active material layer 200, respectively. The first tab groove 210 is used for welding the tab 300, and the provision of the second tab groove 220 improves the yield rate of tab 300 welding. The second tab groove 220 does not require a tab 300. To prevent the current collector 100 from being exposed to the electrolyte, the second tab groove 220 is also filled with an insulating member 400. It is understood that the insulating member 400 in the second tab groove 220 should not protrude from the surface of the active material layer 200.

[0052] The second embodiment of the present application provides a battery (not shown in the figure), which includes the electrode sheet mentioned in any of the above embodiments. It is understood that the battery includes a positive electrode sheet, a separator, and a negative electrode sheet. The positive electrode sheet, the separator, and the negative electrode sheet are formed into an electrode assembly through a winding process or a lamination process. The electrode assembly is wrapped with aluminum-plastic film, dried, and then injected with electrolyte. The lithium-ion battery is obtained through processes such as packaging, standing, forming, and trimming.

[0053] The electrode structure in the embodiment of the first aspect of the present application can be applied to the positive electrode sheet or the negative electrode sheet, so that the positive electrode sheet in the battery of the embodiment of the second aspect of the present application can adopt the above-mentioned electrode structure, and / or the negative electrode sheet can adopt the above-mentioned electrode structure to obtain better battery performance.

[0054] In order to verify the technical effect of the insulating member 400 used in this application, the following comparative experiments were conducted:

[0055] Example 1:

[0056] The thickness of the active material layer 200 on one side is 100 μm, and the length, width, and thickness of the tab 300 are 36 mm, 6 mm, and 0.08 mm, respectively.

[0057] The first tab groove 210 is coated with an insulating member 400 . The insulating member 400 is flush with the active material layer 200 . The thickness of the first coating portion 410 on the surface of the tab 300 is 20 μm.

[0058] The insulating member 400 includes a high thermal conductivity insulating material and an adhesive. The high thermal conductivity insulating material is boehmite, and the adhesive is styrene-butadiene rubber.

[0059] The positive electrode sheet, negative electrode sheet and separator are wound to obtain an electrode assembly with a wound structure, which is then wrapped with an aluminum-plastic film. After drying, the electrolyte is injected into the electrode assembly, and a lithium-ion battery is obtained through processes such as packaging, standing, forming and trimming.

[0060] Comparative Example:

[0061] The difference between this comparative example and Example 1 is that the first tab groove 210 is directly coated with a glue process, and the insulating tape 500 is attached to the active material layer 200 and covered in the first tab groove 210. Except that the insulating member 400 is not coated, the other conditions are the same as those in Example 1.

[0062] Performance testing:

[0063] (1) Cycle performance test: The lithium-ion batteries in Example 1 and the comparative example were placed in a thermostat at 25°C ± 3°C and allowed to stand for 1 hour. They were charged to 4.45V at a constant current of 1C, then charged to 0.05C at a constant voltage of 4.45V and allowed to stand for 10 minutes. They were then discharged to 3.0V at a constant current of 0.5C. This was recorded as one charge and discharge cycle, and the discharge capacity C1 of the lithium-ion battery in the first cycle was recorded. The charge and discharge cycles were performed 700 times according to the above method, and the discharge capacity C2 after 700 cycles was recorded. Five lithium-ion batteries were tested in each group, and the average value of the capacity retention rate was taken to characterize the cycle performance, where capacity retention rate (%) = C2 (mAh) / C1 (mAh) × 100%.

[0064] (2) Charging Temperature Rise Test: The lithium-ion batteries of Example 1 and the comparative example were placed in a thermostat at 25°C ± 3°C and allowed to stand for 1 hour. They were then charged to 4.45V at constant currents of 1C, 1.5C, 2C, 3C, and 4C, respectively. They were then charged to 0.05C at a constant voltage of 4.45V and allowed to stand for 10 minutes. The temperature at 300°C of the negative tab was monitored throughout the charging process. Five lithium-ion batteries were tested in each group, and the average value was taken as the temperature rise at 300°C of the tab.

[0065] The results of the performance test are shown in the following table.

[0066]

[0067] It can be found that Example 1 using the insulating component solution of the present application has good heat dissipation performance, a small temperature rise during charging, a high capacity retention rate, and good overall battery performance.

[0068] The third embodiment of the present application provides an electric device, which includes the battery mentioned in the second embodiment. The electric device can be a new energy vehicle, a digital product such as a computer, or a household appliance such as a cleaning robot or a projector.

[0069] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Various modifications can be made within the scope of knowledge possessed by a person skilled in the art without departing from the spirit of the present invention. In addition, the embodiments of the present invention and the features of the embodiments can be combined with each other unless there is a conflict.

Claims

1. A pole piece, characterized in that: include: a current collector, wherein the current collector is made of a conductive foil; an active material layer, the active material layer being disposed on at least one side of the current collector along its thickness direction, the active material layer being provided with a first tab groove, the first tab groove penetrating the current collector to expose the conductive foil; a tab, the tab being disposed in the first tab slot and connected to the current collector; The first tab groove is further filled with an insulating member, the insulating member covers the tab, and the insulating member is not protruding from the active material layer.

2. The pole piece according to claim 1, characterized in that: The insulating member is flush with a surface of the active material layer.

3. The pole piece according to claim 1, characterized in that: The size of the tab is smaller than that of the first tab slot, so that a foil-exposed space is formed between the tab and the slot wall of the first tab slot, part of the insulating member fills the foil-exposed space, and part of the insulating member covers the tab.

4. The pole piece according to claim 3, characterized in that: The portion of the insulating member covering the electrode tab is set as a first coating portion, and the thickness of the first coating portion is 5 μm to 20 μm.

5. The pole piece according to claim 4, characterized in that: The portion of the insulating member filling the exposed foil space is set as a second coating portion, and a thickness of the second coating portion is greater than a thickness of the first coating portion.

6. The pole piece according to claim 4, characterized in that: The sum of the thickness of the first coating portion and the thickness of the tab is equal to the thickness of the active material layer.

7. The pole piece according to claim 1, characterized in that: The thermal conductivity of the insulating member is greater than or equal to 15 W / (m·K).

8. The pole piece according to claim 1, characterized in that: The active material layer is provided on both sides of the current collector along its thickness direction, one of the active material layers is provided with the first pole tab groove, and the other active material layer is provided with the second pole tab groove, the first pole tab groove and the second pole tab groove are arranged opposite to each other, and the second pole tab groove is filled with the insulating member.

9. A battery, characterized in that A pole piece comprising any one of claims 1 to 8.

10. Electrical equipment, characterized in that: Comprising the battery of claim 9.

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