Pole piece, battery cell and battery

Abstract

The utility model relates to the field of battery production, in particular to a pole piece, a battery cell and a battery. The pole piece comprises a current collector which is provided with a first surface and a second surface which are oppositely arranged, and the first surface comprises a first coating area and a first blank area; the first active material layer is coated in the first coating area, and the first active material layer is provided with a first edge area close to one side of the first blank area; the first conducting strip is connected to the first blank area of the current collector through welding, and the first conducting strip is provided with a first welding area; the pole piece further comprises a first coating layer, and the first coating layer covers at least part of the first edge area of the first active material layer and at least part of the first welding area. By applying the technical scheme provided by the invention, the problems that the performance of the pole piece is poor and the diaphragm is easily punctured in the prior art can be effectively solved.

Description

Technical Field

[0001] This application relates to the field of battery production, and particularly to an electrode sheet, an electrode core, and a battery. Background Art

[0002] Due to many advantages, lithium-ion batteries have become the main power source for consumer electronics and electric vehicles. The safety performance and light weight of lithium-ion batteries have been the focus of consumers in recent years, especially for batteries used in electric vehicles.

[0003] Currently, in the electrode core of a lithium-ion battery, the electrode sheet is a very important component. The electrode sheet generally includes a current collector and a conductive sheet, and the conductive sheet is connected to the current collector by welding.

[0004] However, when the current collector is a composite current collector, after the conductive sheet is welded to the current collector, the conductive sheet is prone to folding or wrinkling, which affects the contact area between the conductive sheet and the current collector, thereby affecting the performance of the electrode sheet, reducing the flatness of the surface of the electrode sheet, and increasing the risk of the separator being punctured. Summary of the Utility Model

[0005] This application provides an electrode sheet, an electrode core, and a battery to solve the problems of poor performance of the electrode sheet and easy puncture of the separator in the related art.

[0006] On the one hand, this application provides an electrode sheet, including:

[0007] A current collector having a first surface and a second surface oppositely arranged in the thickness direction, the first surface including a first coating area and a first blank area adjacent to and connected to the first coating area;

[0008] A first active material layer coated in the first coating area, the first active material layer having a first edge area arranged on the side close to the first blank area;

[0009] A first conductive sheet connected to the first blank area of the current collector, the first conductive sheet having a first welding area;

[0010] Wherein, the electrode sheet further includes a first coating layer covering at least part of the first edge area of the first active material layer and covering at least part of the first welding area.

[0011] In some embodiments, the thickness of the first active material layer located in the first edge area gradually decreases in the direction from the first coating area to the first blank area.

[0012] In some embodiments, a first edge region of the first active material layer has a first active layer surface, the first conductive sheet has a vertical surface close to the first active material layer, the first active layer surface, the vertical surface, and the current collector enclose a filling region, and the first coating layer fills the filling region and covers all of the first welding regions.

[0013] In some embodiments, the width W1 of the first coating layer is between 0.1 mm and 15 mm;

[0014] and / or, the thickness H1 of the first coating layer is between 20 μm and 200 μm; and / or, the thickness H11 of the first coating layer covering the first welding region is between 10 μm and 100 μm;

[0015] and / or, the following is satisfied between the maximum thickness H1 of the first coating layer and the maximum thickness H2 of the first active material layer: 0 < H2 - H1 ≤ 10 μm;

[0016] and / or, the width W2 of the first welding region is between 0.5 mm and 10 mm.

[0017] In some embodiments, the electrode tab further includes a first adhesive layer. Along the first direction of the electrode tab, the first adhesive layer is located between the first surface and the first conductive sheet. Along the second direction of the electrode tab, the first adhesive layer is located between the first active material layer and the first welding region.

[0018] In some embodiments, the width of the first adhesive layer is W3 and the distance between the first welding region and the edge of the current collector close to the first active material layer is W4, and W3 and W4 satisfy: 0.5 ≤ W3:W4 ≤ 0.9;

[0019] and / or,

[0020] the width of the first filling layer is W5 and the distance between the first welding region and the edge of the current collector far from the first active material layer is W6, and W5 and W6 satisfy: 0.1 ≤ W5:W6 ≤ 0.9;

[0021] The width W3 of the first adhesive layer, the width W5 of the first filling layer, and the width W6 of the first blank region satisfy: 0.1 ≤ W3:W6 ≤ 0.4, 0.1 ≤ W5:W6 ≤ 0.4.

[0022] In some embodiments, the width W3 of the first adhesive layer is between 0.05 mm and 4.5 mm;

[0023] and / or, the distance W4 between the first welding region and the edge of the current collector close to the first active material layer is between 0.1 mm and 5 mm;

[0024] and / or, the width W5 of the first filling layer is between 0.05 mm and 4.5 mm;

[0025] And / or, the distance W6 between the first welding area and the edge of the current collector away from the first active material layer is between 0.1 mm and 5 mm;

[0026] And / or, the width W7 of the first blank area is between 0.2 mm and 20 mm.

[0027] In some embodiments, the thickness of the first adhesive layer is the same as the thickness of the first filling layer;

[0028] And / or, the sum of the thickness of the first adhesive layer and the thickness of the first conductive sheet is less than the thickness of the first welding area.

[0029] In some embodiments, the second surface includes a second coating area and a second blank area adjacent to and connected to the second coating area;

[0030] A second active material layer is coated in the second coating area, and the second active material layer has a second edge area disposed on a side close to the second blank area;

[0031] A second conductive sheet is connected to the second blank area of the current collector, and the second conductive sheet has a second welding area;

[0032] Wherein, the thickness of the second active material layer located in the second edge area gradually decreases in the direction from the second coating area to the second blank area; the electrode plate further includes a second coating layer, and the second coating layer covers at least part of the second edge area of the second active material layer and covers at least part of the second welding area.

[0033] On the other hand, the present application provides an electric core, including: a first electrode plate, a second electrode plate, and a separator disposed between the first electrode plate and the second electrode plate, and the first electrode plate, the second electrode plate, and the separator are wound or laminated; wherein, the first electrode plate is the above-mentioned electrode plate, and the conductive structure of the first electrode plate forms the tab structure of the electric core.

[0034] On the other hand, the present application provides a battery, including: an electric core, and the electric core is the above-mentioned electric core.

[0035] The present application provides a pole piece, which includes a current collector, a first active material layer, a first conductive sheet, and a first coating layer. The first surface of the current collector is divided into a first coating area and a first blank area. The first active material layer is coated in the first coating area. The first conductive sheet can be welded in the first blank area. The first coating layer can be coated at the connection between the first active material layer and the first conductive sheet. Specifically, the first active material layer has a first edge area disposed on the side close to the first blank area, and the thickness of the first active material layer within the first edge area gradually decreases in the direction from the first coating area to the first blank area. The first coating layer can cover at least part of the first edge area and cover at least part of the first welding area. When the first coating layer solidifies, it can generate a certain adhesive force, increasing the connection stability between the first conductive sheet and the current collector or the first active material layer, so that when the first conductive sheet is processed subsequently, the edge of the first conductive sheet close to the first coating layer is not easily turned up or deformed. At the same time, the first coating layer can also cover the first conductive sheet and at least part of the first welding area, increasing the connection strength of the first welding area and improving the flatness of the surface of the first conductive sheet, thereby being able to reduce the risk of the conductive sheet piercing the diaphragm. In addition, the first coating layer can also fill the space between the first active material layer and the first conductive sheet, so that the originally thinner areas on the pole piece are filled, thereby improving the thickness uniformity of the pole piece, enabling the pole piece to be evenly pressed during formation, and further contributing to improving the cycle performance of the battery cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The accompanying drawings herein are incorporated into the specification and form a part of the specification, showing embodiments consistent with the present application, and are used together with the specification to explain the principles of the present application.

[0037] Figure 1 Schematic structural diagram of a pole piece provided by an embodiment of the present application;

[0038] Figure 2 For Figure 1 Schematic structural diagram of the current collector of the pole piece;

[0039] Figure 3 For Figure 1 Partial structural diagram of the pole piece, where Figure 5 Shows the schematic structural diagram after the current collector is welded to the first conductive sheet and the second conductive sheet;

[0040] Figure 4 Schematic structural diagram of a pole piece provided by another embodiment of the present application;

[0041] Figure 5 For Figure 4 Exploded structural diagram of the pole piece;

[0042] Figure 6 For Figure 4 Top view of the pole piece.

[0043] Description of the reference numerals:

[0044] 10. Electrode

[0045] 100. Current collector; 101. First surface; 1011. First coating area; 1012. First blank area

[0046] 102. Second surface; 1021. Second coating area; 1022. Second blank area

[0047] 210. First active material layer; 211. First edge area; 2111. First active layer surface

[0048] 220. Second active material layer

[0049] 310. First conductive sheet; 301. Filling area; 311. Vertical surface

[0050] 320. Second conductive sheet

[0051] 410. First welding area; 420. Second welding area

[0052] 510. First coating layer; 520. Second coating layer

[0053] 610. First adhesive layer; 620. Second adhesive layer

[0054] 710. First filling layer; 720. Second filling layer

[0055] Through the above-mentioned drawings, specific embodiments of the present application have been shown, and more detailed descriptions will be given hereinafter. These drawings and the written descriptions are not intended to limit the scope of the concept of the present application in any way, but to illustrate the concept of the present application to those skilled in the art by referring to specific embodiments. Detailed description of the specific embodiments

[0056] In order to make the objectives, technical solutions and advantages of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some, but not all, of the embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts shall fall within the protection scope of the present application.

[0057] Currently, in the battery cell of a lithium-ion battery, the electrode is a very important component. The electrode generally includes a current collector and a conductive sheet, and the conductive sheet is connected to the current collector by welding.

[0058] To improve the safety performance and energy density of lithium-ion batteries, a composite current collector with a polymer insulating matrix in the middle and conductive layers on both sides has been proposed. The composite current collector has a small self-weight and a high energy density, and can effectively prevent lithium-ion batteries from catching fire, exploding, etc. due to internal short circuits when encountering abnormal situations such as collisions, squeezes, and punctures. Therefore, it is used to replace pure metal current collectors.

[0059] However, in the composite current collector, the metal conductive layers on both sides are separated by the insulating matrix, which hinders the conduction of current. To address this problem, currently, a method of double-sided welding conductive sheets in the blank area of the composite current collector is mostly used to achieve the current conduction of the conductive layers on both sides. However, in actual verification, this scheme of directly welding conductive sheets and composite current collectors has many problems in the manufacturing process, and even introduces some uncontrollable risks to the final performance of the battery cell.

[0060] Specifically, currently, when welding conductive sheets and current collectors, the welding area is generally located at the center of the width direction of the conductive sheet, leaving a certain width of the conductive sheet between the welding mark and the active material layer to avoid the heat generated by welding affecting the performance of the active material layer. However, the reserved conductive sheet is prone to problems such as folding, shrinkage, warping, and skewing after welding, which affects the contact area between the conductive sheet and the current collector. The presence of welding protrusions in the welding area also reduces the flatness of the surface of the electrode sheet, thereby increasing the risk of the separator being punctured, and further affecting the performance of the electrode sheet.

[0061] In view of this, the present application provides an electrode sheet. By adding a coating layer on the electrode sheet, the coating layer covers the active material layer and the conductive sheet close to the active material layer. After the coating layer solidifies, it will play a connecting role, improving the connection stability between the conductive sheet, the current collector, and the active material layer, thereby enhancing the performance of the electrode sheet. In addition, the coating layer covering the surface of the conductive sheet can also improve the flatness of the surface of the conductive sheet, thereby reducing the risk of the conductive sheet piercing the separator.

[0062] The electrode sheet provided by the embodiment of the present application will be described below with reference to the accompanying drawings. It should be noted that the electrode sheet provided by the embodiment of the present application can be applied to a battery. The battery can be a secondary battery, that is, the battery in the embodiment of the present application can be charged, discharged, and recycled. The specific type of the battery can include, but is not limited to, lithium batteries, etc. The scenarios where the battery can be used include, but are not limited to, electronic products, energy storage devices, transportation tools, etc., such as mobile communication devices, new energy vehicles, drones, etc. The embodiment of the present application does not make specific limitations on this.

[0063] Figure 1 is a schematic structural diagram of the electrode sheet provided by an embodiment of the present application, Figure 2 is Figure 1 a schematic structural diagram of the current collector of the electrode sheet; Figure 3 is Figure 1 a partial structural diagram of the electrode sheet, whereFigure 5 The structural schematic diagram after welding the current collector with the first conductive sheet and the second conductive sheet is shown.

[0064] Please refer to Figures 1 to 3 As shown, the electrode sheet 10 provided in this embodiment includes: a current collector 100, a first active material layer 210, a first conductive sheet 310, and a first coating layer 510.

[0065] Among them, the current collector 100 has a first surface 101 and a second surface 102 oppositely arranged in the thickness direction. The first surface 101 includes a first coating area 1011 and a first blank area 1012 adjacent to and connected to the first coating area 1011. The first coating area 1011 is used for coating the first active material layer 210, and the first blank area 1012 is used for connecting the first conductive sheet 310.

[0066] The first active material layer 210 is coated within the first coating area 1011 and is used to provide active materials for the electrode sheet. The first active material layer 210 has a first edge area 211 arranged on one side close to the first blank area 1012.

[0067] The first conductive sheet 310 is connected to the first blank area 1012 of the current collector 100 by welding. After welding, a first welding area 410 can be formed on the first conductive sheet 310.

[0068] The electrode sheet 10 further includes a first coating layer 510 that covers at least part of the first edge area 211 of the first active material layer 210 and covers at least part of the first welding area 410.

[0069] Applying the technical solution of this embodiment, the electrode sheet 10 includes a current collector 100, a first active material layer 210, a first conductive sheet 310, and a first coating layer 510. The first surface 101 of the current collector 100 is divided into a first coating area 1011 and a first blank area 1012. The first active material layer 210 is coated within the first coating area 1011. The first conductive sheet 310 can be welded within the first blank area 1012. The first coating layer 510 can be coated at the connection between the first active material layer 210 and the first conductive sheet 310. Specifically, the first active material layer 210 has a first edge area 211 disposed on a side close to the first blank area 1012. The first coating layer 510 can cover at least part of the first edge area 211 and cover at least part of the first welding area 410. When the first coating layer 510 solidifies, it can generate a certain adhesive force, increasing the connection stability between the first conductive sheet 310 and the current collector 100 or the first active material layer 210, such that when processing the first conductive sheet 310 subsequently, the edge of the first conductive sheet 310 close to the first coating layer 510 is not easily turned up or deformed. At the same time, the first coating layer 510 can also cover the first conductive sheet 310 and at least part of the first welding area 410, increasing the connection strength of the first welding area and improving the flatness of the surface of the first conductive sheet 310, thereby being able to reduce the risk of the conductive sheet piercing the separator. Additionally, the first coating layer 510 can also fill the space between the first active material layer 210 and the first conductive sheet 310, such that the originally thinner areas on the electrode sheet 10 are filled, thereby improving the thickness uniformity of the electrode sheet 10, enabling the electrode sheet 10 to be evenly pressed during formation, and further contributing to improving the cycle performance of the battery cell.

[0070] In some embodiments, the thickness of the first active material layer 210 within the first edge area 211 gradually decreases in the direction from the first coating area 1011 to the first blank area 1012 to form a thinning area. The first coating layer 510 can cover at least part of the first edge area 211 and cover at least part of the first welding area 410. The thinning setting of the first blank area 1012 enables more of the first active material layer 210 to be accommodated at the first edge area 211. Additionally, after being roll-pressed, the first active material layer 210 can also be flattened with the first active material layer, thereby ensuring the flatness of the electrode sheet.

[0071] Specifically, as Figure 1As shown, in some embodiments, the first edge region 211 of the first active material layer 210 has a first active layer surface 2111, the first conductive sheet 310 has an upright surface 311 close to the first active material layer 210, the first active layer surface 2111, the upright surface 311, and the current collector 100 enclose a filling area 301, and the first coating layer 510 can fill the filling area 301 and cover the first welding area 410. This setting utilizes the space between the first active layer surface 2111 and the upright surface 311 to ensure the filling amount of the first coating layer 510, thereby enabling the first conductive sheet 310 to have a better connection effect and the electrode sheet to have better performance.

[0072] In some embodiments, the first coating layer 510 can fill the filling area 301 and cover the entire first welding area 410. This setting can improve the connection strength between the first conductive sheet and the current collector at the first welding area, maximize the flatness of the electrode sheet surface, and thereby effectively reduce the probability of the electrode sheet scratching and piercing the separator.

[0073] In some embodiments, the first coating layer 510 can cover a part of the first welding area 410. This setting helps to improve the connection stability of the first conductive sheet 310 while saving the material cost of the first coating layer 510.

[0074] In other embodiments, the first coating layer 510 can also cover the entire first welding area 410. This setting can effectively improve the flatness of the surface of the first welding area 410, reduce the scratching effect of the welding mark on the separator, and thereby reduce the risk of the separator being pierced.

[0075] Furthermore, in some embodiments, the first coating layer 510 includes an active material, a conductive agent, and a binder.

[0076] Specifically, the active material can directly participate in the chemical reaction of the battery and determines the energy storage and release capacity of the battery. These active materials store energy during charging and release energy during discharging. Adding active materials to the first coating layer 510 can improve the chemical performance of the electrode sheet. Exemplarily, when the electrode sheet 10 is a positive electrode sheet, the active materials in the first coating layer 510 can include lithium iron phosphate, lithium cobaltate, etc. Exemplarily, when the electrode sheet 10 is a negative electrode sheet, the active materials in the first coating layer 510 can be graphite or silicon-based materials, etc.

[0077] The function of the conductive agent is to improve the conductivity of the first coating layer 510, which can promote the rapid transfer of electrons, thereby improving the charge-discharge efficiency and power performance of the battery. In addition, the conductive agent is also beneficial to form a conductive network, enabling the conductive performance of the electrode sheet 10 to be effectively improved.

[0078] The function of the binder is to adhere the active material and the conductive agent, and at the same time, it can also improve the bonding effect between the first conductive sheet 310 and the current collector 100, making it difficult for the first conductive sheet 310 to separate from the current collector, ensuring the contact area between the first conductive sheet 310 and the current collector 100, and enabling the electrode sheet to form a stable connection structure.

[0079] Therefore, when the electrode sheet 10 is a positive electrode sheet, since the first coating layer 510 also includes the active material, the conductive agent, and the binder, the proportion of the active material in the positive electrode sheet can be increased, thereby improving the chemical performance of the battery. The conductive agent can improve the conductive effect of the first coating layer 510, increase the moving speed of electrons in the positive electrode sheet, and ensure the over-current capacity of the positive electrode sheet. On the one hand, the binder can ensure the bonding effect on the active material and the conductive agent, and on the other hand, it can also improve the connection stability between the first conductive sheet 310 and the current collector 100.

[0080] At the same time, since the first coating layer 510 can also cover the first welding area 410, the first coating layer 510 fills the depressions, welding holes, etc. during welding in the first welding area 410. On the one hand, it improves the connection strength and conductive ability of the first welding area 410, and at the same time, it also improves the flatness of the first welding area 410, reducing the risk of piercing the separator by the first welding area 410.

[0081] Correspondingly, when the electrode sheet 10 is a negative electrode sheet, since the first coating layer 510 also includes the active material, the conductive agent, and the binder, the proportion of the active material in the negative electrode sheet can be increased, which helps to improve the CB value of the battery, increase the energy density of the battery, and reduce the risk of lithium deposition in the weak connection area (the first welding area). The effects of the conductive agent, the binder, and the covering effect of the first coating layer 510 are the same as those when the electrode sheet 10 is a positive electrode sheet, and will not be elaborated here.

[0082] It should also be noted that in some embodiments, the first active material layer 210 also includes the components of the active material, the conductive agent, and the binder. However, the proportions of the above components in the first active material layer 210 are different from those of the first coating layer 510.

[0083] Specifically, the mass percentage of the active material in the first coating layer 510 is less than the mass percentage of the active material in the first active material layer 210; the resistivity of the first coating layer 510 is lower than the resistivity of the first active material layer 210; the mass percentage of the binder in the first coating layer 510 is greater than the mass percentage of the binder in the first active material layer 210.

[0084] The above-described differential setting method is because the main function of the first active material layer 210 is to provide a large amount of active material to enable the battery to perform charge and discharge functions. Therefore, the mass percentage of the active material in the first coating layer 510 will be less than the mass percentage of the active material in the first active material layer 210. In the first coating layer 510, the conductive agent and the binder will occupy a larger proportion, so that after the first coating layer 510 is coated, the overcurrent capacity and connection stability of the electrode sheet can be further improved.

[0085] In addition, due to the relatively large proportion of the binder in the first coating layer 510, the first coating layer 510 can present a colloidal state rather than a granular state, thus having better adhesiveness.

[0086] Furthermore, the resistivity of the conductive agent in the first coating layer 510 can be less than 0.00001 Ωm, and the resistivity of the conductive agent in the first active material layer 210 can be less than 0.0001 Ωm. There is an order-of-magnitude difference between the two. The conductive agent in the first coating layer 510 has a lower resistivity, that is, higher conductivity. The introduction of a highly conductive agent can relieve the overcurrent pressure in the first welding area, increase the overcurrent area, and reduce the risk of battery thermal runaway caused by temperature rise.

[0087] It should be noted that the resistivity of the first coating layer 510 and the resistivity of the first active material layer 210 can be measured by a film resistance tester. Specifically, the film resistance tester includes a first conductive probe and a second conductive probe. When measuring the resistivity of the first coating layer 510, the first conductive probe and the second conductive probe can be clamped on both sides of the electrode sheet with the first coating layer 510, as Figure 4 shown at A-A in. Similarly, when measuring the resistivity of the first active material layer 210, the first conductive probe and the second conductive probe can be clamped on both sides of the electrode sheet with the first active material layer 210, as Figure 4 shown at B-B in.

[0088] Exemplarily, the material of the conductive agent in the first coating layer 510 can be one or several of carbon nanofibers, carbon nanotubes, and graphene.

[0089] Specifically, in some embodiments, the mass percentage of the main active material in the first coating layer 510 can be 40%-58%, the mass percentage of the binder is greater than or equal to 40%, and the mass percentage of the conductive agent is greater than or equal to 15%. In the first active material layer 210, the proportion of the main active material is between 90%-98%, and the proportion of the binder and the conductive agent accounts for at most only 10%. The proportion of these two is much smaller than that of the two in the first coating layer 510.

[0090] Exemplarily, the values that the mass percentage of the active main material in the first coating layer 510 can take include, but are not limited to, 40%, 45%, 48, 50%, 55%, 58%.

[0091] Exemplarily, the values that the mass percentage of the binder in the first coating layer 510 can take include, but are not limited to, 40%, 41%, 43%, 44%, 45%.

[0092] Exemplarily, the values that the mass percentage of the conductive agent in the first coating layer 510 can take include, but are not limited to, 15%, 16%, 17%, 18%, 19%, 20%.

[0093] It should also be noted that in some embodiments, the binder in the first coating layer 510 is a polymer with an ultra-high weight-average molecular weight. The polymer with an ultra-high weight-average molecular weight can improve the adhesion of the first coating layer 510, enable the first coating layer 510 to maintain viscosity, reduce the probability of powder falling off after the first coating layer 510 solidifies, and improve the reliability of the positive electrode sheet.

[0094] Furthermore, the molecular weight of the polymer with an ultra-high weight-average molecular weight can be between 2 million and 6 million. Exemplarily, the binder can be substances such as ultra-high molecular weight PVDF, ultra-high molecular weight polyethylene, etc.

[0095] As Figure 5 and Figure 6 shown, in some embodiments, the width W1 of the first coating layer 510 is between 0.1 mm and 15 mm. Further, the width W1 of the first coating layer 510 is between 5 mm and 15 mm, so that the first coating layer 510 covers the first active material layer 210 and the first conductive sheet 310.

[0096] Exemplarily, the values that the width W1 of the first coating layer 510 can take include, but are not limited to, 0.1 mm, 1 mm, 5 mm, 7 mm, 9 mm, 10 mm, 12 mm, 14 mm, 15 mm.

[0097] In some embodiments, the thickness H1 of the first coating layer 510 is between 2 μm and 200 μm; further, the thickness H1 of the first coating layer 510 is between 50 μm and 200 μm.

[0098] Exemplarily, the values that the thickness H1 of the first coating layer 510 can take include, but are not limited to, 2 μm, 25 μm, 50 μm, 75 μm, 100 μm, 125 μm, 150 μm, 175 μm, 200 μm.

[0099] In some embodiments, the thickness H11 of the first coating layer 510 covering the first welding area 410 is between 2 μm and 200 μm to ensure the shielding effect of the first coating layer 510 on the welding mark, which helps to improve the flatness of the surface of the electrode sheet.

[0100] In some embodiments, the maximum thickness H1 of the first coating layer 510 and the maximum thickness H2 of the first active material layer 210 satisfy: 0 < H2 - H1 ≤ 10 μm. Such a setting makes the thickness of the first coating layer 510 not exceed that of the first active material layer 210, avoiding the excessive thickness of the electrode sheet and occupying too much space. In addition, the value of H2 - H1 being between 0 μm and 10 μm results in a small difference between the thickness of the first coating layer 510 and the thickness of the first active material layer 210, which helps to ensure the flatness of the surface of the electrode sheet.

[0101] Exemplarily, the values that the difference value of H2 - H1 can take include but are not limited to 0 μm, 1 μm, 2.5 μm, 5 μm, 7.5 μm, 9 μm, 10 μm.

[0102] In some embodiments, the width W2 of the first welding area 410 is between 0.5 mm and 10 mm to ensure the connection effect between the first conductive sheet 310 and the current collector 100.

[0103] Exemplarily, the values that the width W2 of the first welding area 410 can take include but are not limited to 0.5 mm, 1 mm, 5 mm, 7 mm, 9 mm, 10 mm.

[0104] It should be noted that the current collector 100 can be a composite current collector, that is, the current collector includes an insulating matrix layer in the middle, a first metal coating covering the first surface of the insulating matrix layer, and a second metal coating covering the second surface of the insulating matrix layer. Exemplarily, the thickness of the insulating matrix layer is between 1 μm and 25 μm, the thickness of the first metal coating is between 0.3 μm and 25 μm, and the thickness of the second metal coating is between 0.3 μm and 25 μm.

[0105] Exemplarily, the thickness of the first conductive sheet is between 1 μm and 25 μm.

[0106] In addition, it should also be noted that the first conductive sheet 310 and the current collector 100 are welded by roll welding. After roll welding, welding marks can be formed on the surface of the first welding area 410. The welding marks include protrusions and recesses. Affected by the welding process, the recesses include welding grooves and welding through-holes. The welding groove refers to the recess that does not penetrate the electrode sheet, and the welding through-hole refers to the recess that penetrates the current collector 100 and the conductive sheet in the thickness direction of the electrode sheet. These recesses will reduce the conductivity of the electrode sheet and increase the internal resistance of the electrode sheet.

[0107] In this embodiment, a first coating layer 510 is coated on the first welding area 410, and the first coating layer 510 is spread and flattened by a pressing roller so that the first coating layer 510 fills into the above-mentioned recesses. After the first coating layer 510 is air-dried, a solid structure extending into the welding through-holes and welding grooves is formed. Since the first coating layer 510 contains a conductive agent, the over-current capacity of the electrode sheet is effectively guaranteed, and the internal resistance of the electrode sheet is reduced.

[0108] It should be noted that, in order to further increase the conductivity of the electrode sheet, in some embodiments, the process parameters of welding can be adjusted so that the proportion of the welding through-holes accounts for 5% to 40% of the total number of recesses.

[0109] Specifically, the proportion of the weldable through-holes can account for 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40% of the total number of recesses.

[0110] To further improve the connection effect between the first conductive sheet 310 and the current collector 100 and reduce the probability of the edge of the first conductive sheet 310 near the first active material layer 210 turning up, as Figures 4 to 6 shown, in some embodiments, the electrode sheet 10 further includes a first adhesive layer 610. In the first direction, the first adhesive layer 610 is located between the first surface 101 and the first conductive sheet 310, and in the second direction, the first adhesive layer 610 is located between the first active material layer 210 and the first welding area 410.

[0111] In the above structure, the first adhesive layer 610 can bond the first surface 101 of the current collector 100 and the surface of the first conductive sheet 310 close to the current collector 100, thereby effectively reducing the probability of shrinkage, bending, and turning up of the first conductive sheet 310 between the first active material layer 210 and the first welding area 410, and ensuring the connection area between the first conductive sheet 310 and the current collector 100. In addition, the first adhesive layer 610 can also play a role in increasing the strength of the first conductive sheet 310, so that the structural strength of the first conductive sheet 310 between the first active material layer 210 and the first welding area 410 can be improved.

[0112] It should be noted that the above-mentioned first direction refers to the Figure 4 z direction shown in Figure 6 , that is, the thickness direction of the electrode sheet; the above-mentioned second direction refers to the Figure 4 y direction shown in

[0113] Further, in some embodiments, the material of the first adhesive layer 610 includes a polymer elastomer, a tackifier, a plasticizer, a viscosity regulator, and an antioxidant. The above materials enable the first adhesive layer 610 to have no adhesiveness at room temperature and generate adhesiveness in the heated area when heated, so as to adhere the current collector 100 and the first conductive sheet 310. On the one hand, the first adhesive layer 610 can support the first conductive sheet area near the first edge area, avoiding wrinkling and shrinking of the first conductive sheet area near the first edge area during welding; on the other hand, the first adhesive layer 610 has thermal adhesiveness and will generate adhesiveness when excited by heat, so as to adhere the first conductive sheet and the current collector. In the actual battery manufacturing process, when laser die-cutting the tab, the die-cut edges of the first conductive sheet 310 and the second conductive sheet 320 will be adhered together. Since the first adhesive layer 610 is provided between the conductive sheet and the current collector, the risk of folding and skewing of the first conductive sheet 310 and the second conductive sheet 320 during die-cutting can be effectively reduced.

[0114] Further, the polymer elastomer includes one or more of SIS, SBS, SEBS, and SEPS; the tackifier includes one or more of rosin, modified rosin (138 or 145), C5 petroleum resin, C9 petroleum resin, and terpene resin; the plasticizer is one or more of epoxidized soybean oil, DOP, DBP, and paraffin wax 52; the viscosity regulator is one or more of paraffin wax, microcrystalline wax, synthetic wax (PE or PP), and Forton wax; the antioxidant is one or more of N-phenyl-β-naphthylamine and 2,6-di-tert-butyl-p-cresol.

[0115] Further, as Figures 4 to 6 shown, in some embodiments, the electrode sheet 10 further includes a first filling layer 710, and the first filling layer 710 is located between the first surface 101 and the first conductive sheet 310, and the first filling layer 710 is located between the first welding area 410 and the edge of the current collector 100 away from the first active material layer 210.

[0116] In the above structure, when the first adhesive layer 610 is provided on the electrode sheet 10, the setting of the first filling layer 710 can effectively support the first conductive sheet 310 and ensure the flatness of the first conductive sheet 310.

[0117] Specifically, the material of the first filling layer 710 includes conductive adhesive, and the conductive adhesive includes conductive filler, matrix resin, diluent, curing agent, and plasticizer. The above materials enable the first filling layer 710 to not only support the first conductive sheet 310 but also improve the conductivity between the first conductive sheet 310 and the current collector. The conductive adhesive can form a conductive network structure, increase the current-carrying area, relieve the current-carrying pressure in the welding area, thereby improving the current-carrying capacity between the first conductive sheet 310 and the current collector and reducing the temperature rise phenomenon during the charge and discharge process of the battery.

[0118] Furthermore, the conductive filler may be composed of one or several carbon-based composite materials, the matrix resin is composed of one or several of epoxy resin, polyurethane, and polyimide resin, the curing agent may be an alkaline curing agent or an acidic curing agent, and the diluent may be an active diluent or an inactive diluent.

[0119] Of course, in other embodiments, the material of the first filling layer 710 is the same as that of the first coating layer 510. Alternatively, the material of the first filling layer 710 is the same as that of the first active material layer 210.

[0120] As Figure 6 shown, in some embodiments, the width of the first bonding layer 610 is W3 and the distance between the first welding region 410 and the edge of the current collector 100 close to the first active material layer 210 is W4, and W3 and W4 satisfy: 0.5 ≤ W3:W4 ≤ 0.9. Thus, on the one hand, the bonding effect of the first bonding layer 610 on the first conductive sheet 310 is satisfied, and at the same time, the usage amount of the material of the first bonding layer 610 is controlled, which helps to control the cost. Exemplarily, the values that the ratio of W3:W4 can take include but are not limited to 0.5, 0.6, 0.7, 0.8, 0.9.

[0121] In some embodiments, the width of the first filling layer 710 is W5 and the distance between the first welding region 410 and the edge of the current collector 100 far from the first active material layer 210 is W6, and W5 and W6 satisfy: 0.1 ≤ W5:W6 ≤ 0.9. Thus, on the one hand, the conductivity between the first conductive sheet 310 and the current collector is ensured, and at the same time, the usage amount of the material of the first filling layer 710 is controlled, which helps to control the cost.

[0122] It should also be noted that the ratio of W5:W6 needs to be less than or equal to 0.9, so that the width of the first filling layer 710 is less than W6 to avoid the risk of conduction on the welding mark. Therefore, 0.1 ≤ W5:W6 ≤ 0.9 enables the first filling layer 710 to achieve the effect and avoid risks. Further, the ratio of W5:W6 is between 0.1 and 0.9.

[0123] Exemplarily, the values that the ratio of W5:W6 can take include but are not limited to 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9.

[0124] In some embodiments, the width W3 of the first adhesive layer 610, the width W5 of the first filling layer 710, and the width W7 of the first blank area 1012 satisfy: 0.1 ≤ W3:W7 ≤ 0.4, 0.1 ≤ W5:W7 ≤ 0.4. The above settings make the widths of the first adhesive layer 610, the width W5 of the first filling layer 710, and the width range of the first welding area 410 reasonable, effectively utilizing the space of the first blank area 1012 to optimize the performance of the electrode sheet.

[0125] Exemplarily, the values that the ratio of W3:W7 can take include, but are not limited to, 0.1, 0.2, 0.3, and 0.4.

[0126] Exemplarily, the values that the ratio of W5:W7 can take include, but are not limited to, 0.1, 0.2, 0.3, and 0.4.

[0127] It should also be noted that the width of the first edge area is W1, and the width of the part of the first active material layer 210 covering the first edge area is less than or equal to W1. This way can not only make the first coating layer 510 cover the first active material layer 210, thus ensuring the connection effect on the first conductive sheet 310. In addition, the above structure also enables the thickness of the first active material layer 210 to be less than or equal to the thickness of the first active material layer 210 by adjusting the rolling pressure, avoiding the electrode sheet from being too thick.

[0128] Furthermore, as Figure 6 shown, in some embodiments, the width W3 of the first adhesive layer is in the range of 0.05 mm - 4.5 mm. Exemplarily, the values that W3 can take include, but are not limited to, 0.05 mm, 0.1 mm, 0.5 mm, 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm.

[0129] The distance W4 between the first welding area and the edge of the current collector close to the first active material layer is in the range of 0.1 mm - 5 mm. Exemplarily, the values that W4 can take include, but are not limited to, 0.1 mm, 0.5 mm, 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm, 5 mm.

[0130] The width W5 of the first filling layer is in the range of 0.05 mm - 4.5 mm. Exemplarily, the values that W5 can take include, but are not limited to, 0.05 mm, 0.1 mm, 0.5 mm, 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm.

[0131] The distance W6 between the first welding area and the edge of the current collector away from the first active material layer is between 0.1 mm and 5 mm. Exemplarily, the values that W6 can take include, but are not limited to, 0.1 mm, 0.5 mm, 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm, 5 mm.

[0132] The width W7 of the first blank area is between 0.2 mm and 20 mm. Exemplarily, the values that W7 can take include, but are not limited to, 0.2 mm, 0.5 mm, 1 mm, 5 mm, 10 mm, 15 mm, 20 mm.

[0133] In some embodiments, the thickness of the first adhesive layer 610 and the thickness of the first filling layer 710 can be the same, which can ensure the flatness of the first conductive sheet 310 while facilitating processing, and at the same time can prevent problems such as welding deviation caused by the sliding of the first conductive sheet due to thickness differences.

[0134] In addition, it should be noted that the thickness of the first adhesive layer 610 and the thickness of the first conductive sheet 310 can be less than the thickness of the first welding area 410. This thickness relationship can reduce the probability of warping of the first conductive sheet 310 after welding, and facilitate the coating and rolling of the first coating layer and other processes.

[0135] It should also be noted that in some embodiments, the second surface 102 of the current collector 100 includes a second coating area 1021 and a second blank area 1022 adjacent to and connected to the second coating area 1021; the structure connected to the second blank area 1022 and the coating provided are the same as those of the first blank area 1012, and the material of the second active material layer 220 is the same as the material of the first active material layer 210. That is, the structure on the second surface 102 is symmetric with the structure on the first surface 101.

[0136] Specifically, the second active material layer 220 is coated in the second coating area 1021, and the second active material layer 220 has a second edge area provided on the side close to the second blank area 1022; the second conductive sheet is connected to the second blank area 1022 of the current collector 100 by welding, and the second conductive sheet has a second welding area; wherein, the thickness of the second active material layer 220 located in the second edge area gradually decreases in the direction from the second coating area 1021 to the second blank area 1022; the electrode plate 10 further includes a second coating layer 520, and the second coating layer 520 covers at least part of the second edge area of the second active material layer 220 and covers at least part of the second welding area.

[0137] In addition, a second adhesive layer 620 and a second filling layer 720 are provided on the second surface 102. The structures and functions of these two layers are the same as those of the first adhesive layer 610 and the first filling layer 710, and thus will not be elaborated herein in this embodiment.

[0138] The present application provides an electric core. Embodiments of the electric core of the present application include: a first electrode tab, a second electrode tab, and a separator disposed between the first electrode tab and the second electrode tab.

[0139] Specifically, the first electrode tab, the second electrode tab, and the separator are wound or laminated to form a shape; wherein, the first electrode tab is the above-mentioned electrode tab, and the conductive structure of the first electrode tab forms the tab structure of the electric core.

[0140] Since the electrode tab of the present application has the advantages of high structural strength, strong conductivity, and low risk of lithium plating, the electric core having the same also has the above advantages.

[0141] The present application further provides a battery, including: an electric core, where the electric core is the above-mentioned electric core. Since the electric core of the present application has the advantages of high strength, strong conductivity, and low risk of lithium plating, the battery having the same also has the advantages of good functionality, low risk of lithium plating, and long service life.

[0142] In the description of the present application, it should be noted that unless otherwise clearly specified and limited, the terms "installed", "connected", and "coupled" should be understood in a broad sense. For example, it may be a fixed connection, or may be indirectly connected through an intermediate medium, and may be the internal communication of two components or the interaction relationship between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances.

[0143] In the description of the present application, it should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "front", "rear", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation to the present application.

[0144] The terms "first", "second", "third", "fourth", etc. (if any) in the description, claims, and drawings of the present application are used to distinguish similar objects, and do not have to be used to describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein, for example.

[0145] In addition, the terms "comprise" and "include" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or apparatuses.

[0146] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application and are not intended to limit them. Although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A pole piece, characterized in that, Comprising: A current collector, the current collector having a first surface and a second surface oppositely disposed in the thickness direction, the first surface including a first coating region and a first blank region adjacent to and connected to the first coating region; A first active material layer coated in the first coating region, the first active material layer having a first edge region disposed on a side close to the first blank region; A first conductive sheet connected to the first blank region of the current collector, the first conductive sheet having a first welding region; Wherein, the electrode sheet further includes a first coating layer, the first coating layer covering at least part of the first edge region of the first active material layer and covering at least part of the first welding region.

2. The pole piece according to claim 1, wherein The thickness of the first active material layer located within the first edge region gradually decreases in the direction from the first coating region to the first blank region.

3. The pole piece according to claim 2, characterized in that, The first edge region of the first active material layer has a first active layer surface, the first conductive sheet has a vertical surface close to the first active material layer, the first active layer surface, the vertical surface and the current collector enclose a filling region, and the first coating layer is at least partially located in the filling region.

4. The electrode sheet according to any one of claims 1 to 3, characterized in that The width W1 of the first coating layer is between 0.1 mm and 15 mm; And / or, the thickness H1 of the first coating layer is between 20 μm and 200 μm; And / or, the thickness of the first coating layer covering the first welding region is between 10 μm and 100 μm; And / or, the maximum thickness H1 of the first coating layer and the maximum thickness H2 of the first active material layer satisfy: 0 ≤ H2 - H1 ≤ 10 μm; And / or, the width W2 of the first welding region is between 0.5 mm and 10 mm.

5. The pole piece according to any one of claims 1 to 3, characterized in that, The electrode sheet further includes a first adhesive layer, along the first direction of the electrode sheet, the first adhesive layer is located between the first surface and the first conductive sheet, and along the second direction of the electrode sheet, the first adhesive layer is located between the first active material layer and the first welding region.

6. The electrode tab according to claim 5, wherein The electrode sheet further includes a first filling layer, the first filling layer is located between the first surface and the first conductive sheet, and the first filling layer is located between the first welding region and the edge of the current collector away from the first active material layer.

7. The electrode sheet according to claim 6, wherein The width of the first adhesive layer is W3, the distance between the first welding region and the edge of the current collector close to the first active material layer is W4, and W3 and W4 satisfy: 0.5 ≤ W3:W4 ≤ 0.9; And / or, The width of the first filling layer is W5, the distance between the first welding region and the edge of the current collector away from the first active material layer is W6, and W5 and W6 satisfy: 0.1 ≤ W5:W6 ≤ 0.9; And / or, The width W3 of the first adhesive layer, the width W5 of the first filling layer, and the width W7 of the first blank region satisfy: 0.1 ≤ W3:W7 ≤ 0.4, 0.1 ≤ W5:W7 ≤ 0.

4.

8. The pole piece according to claim 6, characterized in that, The width W3 of the first adhesive layer is between 0.05 mm and 4.5 mm; And / or, the distance W4 between the first welding area and the edge of the current collector close to the first active material layer is 0.1 mm - 5 mm; And / or, the width W5 of the first filling layer is 0.05 mm - 4.5 mm; And / or, the distance W6 between the first welding area and the edge of the current collector away from the first active material layer is 0.1 mm - 5 mm; And / or, the width W7 of the first blank area is 0.2 mm - 20 mm.

9. The pole piece according to claim 6, characterized in that, The thickness of the first adhesive layer is the same as that of the first filling layer; And / or, the sum of the thickness of the first adhesive layer and the thickness of the first conductive sheet is less than the thickness of the first welding area.

10. The pole piece according to claim 1, wherein, The second surface includes a second coating area and a second blank area adjacent to and connected to the second coating area; A second active material layer is coated in the second coating area, and the second active material layer has a second edge area disposed on a side close to the second blank area; A second conductive sheet is connected to the second blank area of the current collector, and the second conductive sheet has a second welding area; Wherein, the thickness of the second active material layer located in the second edge area gradually decreases in the direction from the second coating area to the second blank area; the electrode plate further includes a second coating layer, and the second coating layer covers at least part of the second edge area of the second active material layer and covers at least part of the second welding area.

11. A battery cell, characterized in that, Comprising: A first electrode plate, a second electrode plate, and a separator disposed between the first electrode plate and the second electrode plate, and the first electrode plate, the second electrode plate, and the separator are wound or laminated; Wherein, the first electrode plate is the electrode plate according to any one of claims 1 to 10, and the conductive structure of the first electrode plate forms the tab structure of the battery cell.

12. A battery, characterized in that, Comprising: A battery cell, and the battery cell is the battery cell according to claim 11.

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