Pole piece and battery

Abstract

The invention relates to the technical field of batteries, and discloses a pole piece and a battery. The pole piece comprises a pole piece body which comprises a current collector and is provided with a tab connecting area; the tab is provided with a connecting part and an extending part; the first adhesive layer is arranged in the tab connecting area, the first adhesive layer is located between the connecting part and the current collector in the tab connecting area in the thickness direction of the tab, a through hole penetrating through the tab is formed in the connecting part, at least part of the first adhesive layer is embedded into the through hole, and the heat conductivity coefficient of the first adhesive layer is 1.5 W / (m.K)-50 W / (m.K). The connecting part of the tab is bonded with the current collector through the first adhesive layer, so that the tab is electrically connected with the current collector, the current collector cannot be damaged by the bonding mode, the conductivity of the current collector is ensured, and the normal development of the battery capacity is ensured; the through holes are formed in the tabs to increase evaporation channels in the fixing process of the first adhesive layer, so that rapid heat dissipation is realized, the fixing time is shortened, the curing efficiency is improved, the temperature rise of areas near the tabs is reduced, the safety performance of the battery is improved, and the service life of the battery is prolonged.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and particularly to a pole piece and a battery. Background Art

[0002] In the field of batteries, the positive and negative electrodes of a battery are usually electrically connected to the outside of the battery case through pole ears to achieve the conduction between the battery and an external circuit. The pole ears are generally made of metals such as aluminum, nickel, copper and their coated materials.

[0003] In related technologies, in order to connect the pole ear to the positive electrode sheet or the negative electrode sheet, it is usually necessary to clean a part of the active coating on the pole piece to form a single-sided empty foil area or a double-sided empty foil area for connecting with the pole ear. The pole ear is connected to the empty foil area by welding methods such as ultrasonic welding or laser welding. During the welding process of the pole ear, it is easy to generate welding mark protrusions, which may cause the risk of piercing the separator or even damaging the current collector structure and triggering a short circuit. When the pole ear is welded to the single-sided empty foil area, the heat generated by the welding will affect the activity of the active material on the opposite surface of the single-sided empty foil area, reducing the ability of the active layer to intercalate and deintercalate lithium, resulting in the inability to exert the battery capacity. In severe cases, it may even cause the precipitation of lithium dendrites on the negative electrode and pose a safety problem. Summary of the Invention

[0004] In view of this, the present invention provides a pole piece and a battery to solve the problems of damaging the separator and the current collector and triggering a short circuit during the welding of the pole ear to the current collector and the inability to exert the battery capacity.

[0005] In a first aspect, the present invention provides a pole piece, comprising: a pole piece body including a current collector, and the pole piece body has a pole ear connection area; a pole ear having a connection portion connected to the pole ear connection area and an extending portion extending beyond the edge of the pole piece body; a first adhesive layer disposed in the pole ear connection area. Along the thickness direction of the pole ear, the first adhesive layer is located between the connection portion and the current collector of the pole ear connection area. A through hole penetrating the pole ear along the thickness direction of the pole ear is formed in the connection portion, and at least a part of the first adhesive layer is embedded in the through hole. The thermal conductivity of the first adhesive layer is 1.5 W / (m·K) - 50 W / (m·K).

[0006] In an alternative embodiment, along the length direction of the electrode tab, the electrode tab connection region is disposed in the middle of the electrode tab body; and / or, on the same side in the length direction of the electrode tab, the distance L3 between the edge of the first adhesive layer and the edge of the electrode tab connection region is 0-8 mm; and / or, along the width direction of the electrode tab, the distance L4 between the edge of the first adhesive layer and the edge of the electrode tab connection region close to the edge of the first adhesive layer is 0-8 mm; and / or, the dimension L1 of the through hole in the length direction of the electrode tab is 50 μm-2000 μm; and / or, the dimension L2 of the through hole in the width direction of the electrode tab is 50 μm-2000 μm; and / or, along the thickness direction of the electrode tab, the projected area S1 of the through hole on the first surface of the current collector and the projected area S2 of the connecting portion on the first surface satisfy: 0.1 ≤ S1 / S2 ≤ 0.8; and / or, the shape of the through hole is circular, oval, linear or polygonal.

[0007] In an alternative embodiment, the current collector has a first surface and a second surface that are oppositely disposed; the electrode tab body further includes: a first active material layer disposed on the first surface, an electrode tab groove is provided on the first active material layer, the current collector includes a single-sided empty foil area, and the first surface of the single-sided empty foil area is exposed in the electrode tab groove; a second active material layer disposed on the second surface, the area of the second surface opposite to the single-sided empty foil area is covered by the second active material layer, the single-sided empty foil area forms an electrode tab connection region, and the connecting portion is connected to the single-sided empty foil area.

[0008] In an alternative embodiment, along the thickness direction of the electrode tab, the connecting portion has a third surface facing the current collector, a non-through hole that does not penetrate the connecting portion along the thickness direction of the electrode tab is provided on the third surface, the depth of the non-through hole is less than the thickness of the electrode tab, the non-through hole forms a concave portion on the third surface, the connecting portion has a fourth surface away from the current collector, and the fourth surface has a convex portion corresponding to the concave portion.

[0009] In an alternative embodiment, on the side of the connecting portion facing the current collector, a protrusion is formed at the edge of the through hole, and the height h of the protrusion along the thickness direction of the electrode tab is 6 μm-59 μm; and / or, at least part of the protrusion is in contact with the current collector.

[0010] In an alternative embodiment, the thickness T1 of the connecting portion is less than the thickness T of the protruding portion; and / or, the thickness T1 of the connecting portion and the thickness T of the protruding portion satisfy: 20% ≤ T1 / T ≤ 90%; and / or, the thickness T1 of the connecting portion is 30 μm-100 μm.

[0011] In an alternative embodiment, the first adhesive layer is a conductive adhesive layer, and the first adhesive layer includes conductive fillers and polymer fillers; based on the mass of the first adhesive layer, the mass ratio of the conductive fillers is 60%-95%, and the mass ratio of the polymer fillers is 3%-40%; and / or, the conductive fillers include at least one of gold powder, silver powder, copper powder, aluminum powder, nickel powder, carbon black, graphite, carbon nanotubes, and graphene, and the polymer fillers include at least one of epoxy resin, silicone resin, polyimide resin, phenolic resin, polyolefin, styrene-butadiene rubber, polystyrene, and polymethyl methacrylate.

[0012] In an alternative embodiment, the first adhesive layer further includes a support body, and the support body includes SiO 2 , Al 2 O 3 , ZrO 2 , at least one of polymer particles, mesophase carbon microspheres, carbides, titanium nitride, tin, and tin bismuth alloy, and / or, the particle size of the support body is larger than that of the conductive fillers.

[0013] In an alternative embodiment, based on the mass of the first adhesive layer, the mass ratio of the support body is 1%-10%; and / or, the shape of the support body is spherical or ellipsoidal; and / or, the particle size of the support body is 5μm-30μm; and / or, the thickness of the first adhesive layer is 3μm-50μm; and / or, the thickness T of the tab and the thickness t of the first adhesive layer satisfy: 0.6≤T / t≤50.

[0014] In an alternative embodiment, along the width direction of the electrode sheet, the current collector has an edge close to the protruding portion, and along the width direction of the electrode sheet, the distance D1 between one side of the first adhesive layer close to the edge and the edge is 0.2mm-2mm; and / or, along the thickness direction of the electrode sheet, the projected area S2 of the connecting portion on the first surface of the current collector and the projected area S3 of the first adhesive layer on the first surface satisfy: 20%≤S2 / S3≤150%.

[0015] In an alternative embodiment, a connecting member is provided on the portion of the first adhesive layer exceeding the connecting portion; and / or, a first insulating member is provided on the surface of the connecting portion away from the current collector.

[0016] In a second aspect, the present invention further provides a battery, including a separator and at least two electrode sheets with opposite polarities, and the at least two electrode sheets with opposite polarities are respectively a positive electrode sheet and a negative electrode sheet. The positive electrode sheet, the separator, and the negative electrode sheet are stacked and wound. At least one of the positive electrode sheet and the negative electrode sheet is the above-mentioned electrode sheet; when the positive electrode sheet is the above-mentioned electrode sheet, the tab is a positive tab, and the current collector is a positive current collector; and / or, when the negative electrode sheet is the above-mentioned electrode sheet, the tab is a negative tab, and the current collector is a negative current collector.

[0017] In an alternative embodiment, both the positive electrode sheet and the negative electrode sheet are the above-mentioned electrode sheets. The positive electrode sheet includes a positive current collector and a positive active material layer provided on the surface of the positive current collector. The positive electrode sheet includes a first groove, and the thickness of the positive active material layer in the first groove is less than the thickness of the positive active material layer in other regions of the positive electrode sheet except the first groove. Along the thickness direction of the battery, the first groove is disposed opposite to the negative electrode tab, and the positive projection of the negative electrode tab in the thickness direction of the battery is located in the first groove; and / or, the negative electrode sheet includes a negative current collector and a negative active material layer provided on the surface of the negative current collector. The negative electrode sheet includes a second groove formed by the absence of the negative active material layer. Along the thickness direction of the battery, the second groove is disposed opposite to the positive electrode tab, and the positive projection of the positive electrode tab in the thickness direction of the battery is located in the second groove.

[0018] In an alternative embodiment, when the positive electrode sheet includes a first groove, a second insulating member is provided on the side of the positive electrode sheet facing the negative electrode tab, and the second insulating member at least partially covers the first groove; and / or, when the negative electrode sheet includes a second groove, a third insulating member is provided on the side of the negative electrode sheet facing the positive electrode tab, and at least part of the third insulating member covers the second groove.

[0019] The technical solution of the present application has the following advantages:

[0020] The connecting part of the tab is bonded to the current collector through the first adhesive layer to achieve the electrical connection between the tab and the current collector. The bonding method will not damage the current collector, ensuring the conductive ability of the current collector, and thus ensuring the normal performance of the battery capacity. This effectively solves the problem that the battery capacity cannot be fully utilized due to the damage of the current collector during the welding of the tab and the current collector. When the first adhesive layer is bonded to the tab, a thermal curing reaction needs to be carried out under certain temperature conditions. In this application, the first adhesive layer with a specific range of thermal conductivity coefficients combined with the structure of through holes provided on the connecting part of the tab can improve the curing effect of the first adhesive layer, prevent excessive heat generation in the tab area of the battery including this electrode due to poor curing, reduce the temperature rise in the tab position of the battery including this electrode and its nearby areas, and greatly improve the battery cycle performance.During the cycling process of the battery, due to the relatively high current density at the tab position, there is usually a risk of overheating at this position. Overheating can cause the temperature to rise in the tab area and the adjacent electrode area, increasing the side reactions between the materials in this area and the electrolyte, deteriorating the cycling performance of the battery. By providing through holes in the tabs, the first adhesive layer can penetrate into the through holes, increasing the contact area between the first adhesive layer and the tabs, thereby enhancing the bonding force and conductivity between the tabs and the current collector, reducing the internal resistance of the battery. In addition, the through holes in the tabs can impose a certain restraint on the first adhesive layer, inhibiting excessive swelling of the first adhesive layer after contact with the electrolyte, which may lead to unstable tab bonding and more heat generation, and the safety risk caused by a sharp increase in temperature. Further, the setting of the through holes can increase the evaporation channels during the fixing process of the first adhesive layer, enabling the heat of the first adhesive layer to be transferred outward through the through holes, achieving rapid heat dissipation, shortening the curing time, and improving the curing efficiency. If no through holes are provided on the connecting part, there are no evaporation channels in the overlapping part of the first adhesive layer and the connecting part, and the heat of the first adhesive layer can only be transferred outward through the connecting part, resulting in an overly long curing time for the first adhesive layer, which may damage the network structure between the polymers in the first adhesive layer, and then lead to uneven curing of the first adhesive layer, unstable tab connection, excessive heat generation in the area near the tabs of the battery, and too high a temperature rise in the area near the tabs, affecting the cycling performance of the battery. The thermal conductivity of the first adhesive layer affects the curing effect of the first adhesive layer. When the thermal conductivity coefficient of the first adhesive layer is in the range of 1.5 W / (m·K) - 50 W / (m·K), the first adhesive layer is heated evenly during the curing process, the curing time is appropriate, and the curing effect is good. However, if the thermal conductivity coefficient of the first adhesive layer is not within the above range, it will lead to an overly long curing time, causing damage to the polymer network inside the first adhesive layer or loose network connection, increasing the heat generation at the tab position, and affecting the cycling performance of the battery. On the other hand, during the charge and discharge process of the battery, especially when the charge and discharge rate is relatively high, the current flows through the tabs and the junction between the tabs and the current collector. Due to the existence of resistance, heat cannot be released by converting the current into heat on the tabs. At this time, if the thermal conductivity coefficient of the first adhesive layer is within the above range, the first adhesive layer at the tabs and their junctions can quickly transfer the heat at the tab position, preventing the continuous accumulation of heat from causing the battery temperature to rise and reducing the cycling performance of the battery.

[0021] Additional aspects and advantages of the embodiments of the present application will be described and shown in part in the subsequent description, or will be elucidated through the implementation of the embodiments of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0023] Figure 1 Top view of the first type of electrode sheet in the embodiment of the present invention;

[0024] Figure 2 For Figure 1 Schematic structural diagram of the cross-section of the electrode sheet shown along its length direction;

[0025] Figure 3 Top view of the first type of tab and seal in the embodiment of the present invention;

[0026] Figure 4 Top view of the second type of tab and seal in the embodiment of the present invention;

[0027] Figure 5 Top view of the third type of tab and seal in the embodiment of the present invention;

[0028] Figure 6 Top view of the fourth type of tab and seal in the embodiment of the present invention;

[0029] Figure 7 Cross-sectional view of the fifth type of electrode sheet and seal in the embodiment of the present invention;

[0030] Figure 8 For Figure 7 Partial enlarged schematic diagram of A in

[0031] Figure 9 Top view of the sixth type of electrode sheet and seal in the embodiment of the present invention;

[0032] Figure 10 For Figure 9 Cross-sectional view taken along the C-C direction of the electrode sheet and seal shown;

[0033] Figure 11 Schematic structural diagram of a battery in the embodiment of the present invention;

[0034] Figure 12 For Figure 11 Schematic structural diagram of a part of the battery;

[0035] Figure 13 For Figure 12 Partial enlarged schematic diagram of B in

[0036] Figure 14Schematic diagram of a partial structure of another battery according to an embodiment of the present invention.

[0037] Description of reference numerals:

[0038] 1. Electrode plate; 101. Current collector; 1013. Edge; 102. First active material layer; 1021. Tab groove; 103. Tab; 1031. Connection part; 1032. Protruding part; 1033. Through hole; 1034. Protrusion; 104. First adhesive layer; 105. First insulating member; 106. Second active material layer; 107. Seal; 108. Connector.

[0039] 2. Positive electrode plate; 201. Positive current collector; 202. Positive active material layer; 203. Positive tab; 204. First groove; 205. Second insulating member.

[0040] 3. Separator

[0041] 4. Negative electrode plate; 401. Negative current collector; 402. Negative active material layer; 403. Negative tab; 404. Second groove; 405. Third insulating member. Detailed implementation manners

[0042] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative efforts shall fall within the protection scope of the present invention.

[0043] The following combines Figures 1 to 14 , and describes the embodiments of the present invention.

[0044] According to an embodiment of the present invention, on the one hand, a provided electrode plate 1 includes: an electrode plate body, a tab 103, and a first adhesive layer 104. The electrode plate body includes a current collector 101, and the electrode plate body has a tab connection area; the tab 103 has a connection part 1031 connected to the tab connection area and a protruding part 1032 protruding from the edge of the electrode plate body; the first adhesive layer 104 is disposed in the tab connection area. Along the thickness direction of the tab 103, the first adhesive layer 104 is located between the connection part 1031 and the current collector 101 in the tab connection area. A through hole 1033 penetrating the tab 103 along the thickness direction of the tab 103 is formed in the connection part 1031, at least part of the first adhesive layer 104 is embedded in the through hole 1033, and the thermal conductivity of the first adhesive layer 104 is 1.5 W / (m·K) - 50 W / (m·K).

[0045] When applying the electrode tab 1 of this embodiment, the connecting portion 1031 of the electrode ear 103 is bonded to the current collector 101 through the first adhesive layer 104 to achieve the electrical connection between the electrode ear 103 and the current collector 101. The bonding method will not damage the current collector 101, ensuring the conductivity of the current collector 101, and thus ensuring the normal performance of the battery capacity. This effectively solves the problem that the battery capacity cannot be fully utilized due to the damage of the current collector 101 during the welding of the electrode ear 103 and the current collector 101.

[0046] When the first adhesive layer 104 is bonded to the electrode ear, a thermal curing reaction needs to be carried out under certain temperature conditions. The structure of the first adhesive layer 104 with a specific range of thermal conductivity coefficient combined with the through hole 1033 provided on the connecting portion 1031 of the electrode ear can improve the curing effect of the first adhesive layer, prevent excessive heat generation in the battery electrode ear area including this electrode tab due to poor curing, and reduce the temperature rise in the electrode ear position and its nearby area of the battery including this electrode tab, greatly improving the battery cycle performance.

[0047] During the cycling of the battery, due to the relatively high current density at the electrode ear position, there is usually a risk of overheating at this position. Overheating will cause the temperature of the electrode ear area and its nearby electrode tab area to rise, resulting in an increase in side reactions between the materials in this area and the electrolyte, deteriorating the battery cycle performance. By providing through holes on the electrode ear, the first adhesive layer can penetrate into the through holes, increasing the contact area between the first adhesive layer and the electrode ear, thereby enhancing the bonding force and conductivity between the electrode ear and the current collector, reducing the battery internal resistance. In addition, the through holes on the electrode ear can impose a certain restraint on the first adhesive layer, inhibiting the excessive swelling of the first adhesive layer after contacting the electrolyte, which may lead to unstable bonding of the electrode ear and more heat generation, and the safety risk caused by a sharp increase in temperature.

[0048] The further provision of vias can increase the evaporation channels during the fixation process of the first adhesive layer, enabling the heat of the first adhesive layer to be transferred outward through the vias, achieving rapid heat dissipation, shortening the curing time, and improving the curing efficiency. If no vias are provided on the connecting portion, there are no evaporation channels in the overlapping part of the first adhesive layer and the connecting portion, and the heat of the first adhesive layer can only be transferred outward through the connecting portion, resulting in an overly long curing time for the first adhesive layer, which may damage the network structure between the polymers in the first adhesive layer, further leading to uneven curing of the first adhesive layer, unstable connection of the tab, excessive heat generation in the area near the tab of the battery, and too high a temperature rise in the area near the tab, affecting the cycle performance of the battery; the thermal conductivity of the first adhesive layer affects the curing effect of the first adhesive layer. When the thermal conductivity coefficient of the first adhesive layer is within the range of 1.5 W / (m·K) - 50 W / (m·K), the first adhesive layer is heated evenly during the curing process, the curing time is appropriate, and the curing effect is good. However, if the thermal conductivity coefficient of the first adhesive layer is not within the above range, it will lead to an overly long curing time, causing damage to the polymer network inside the first adhesive layer or loose network connection, increasing the heat generation at the tab position, and affecting the cycle performance of the battery. On the other hand, during the charging and discharging process of the battery, especially when the charging and discharging rate is large, the current flows through the tab and the junction of the tab and the current collector. Due to the existence of resistance, heat cannot be released by converting the current into heat on the tab. At this time, if the thermal conductivity coefficient of the first adhesive layer is within the above range, the adhesive of the first adhesive layer at the tab and its junction can quickly transfer the heat at the tab position, preventing the continuous accumulation of heat from causing the battery temperature to rise and reducing the cycle performance of the battery.

[0049] It should be noted that when the battery is in a high-temperature environment, if the thermal conductivity coefficient of the first adhesive layer is large, it may cause the heat transfer to accumulate on the metal strip tab, and the heat accumulation will increase the risk of diaphragm shrinkage at the tab position, resulting in short circuit due to positive and negative contact.

[0050] In one embodiment, along the length direction of the electrode plate 1, the tab connection area is arranged in the middle of the electrode plate body. Setting the tab in the middle of the electrode plate body can shorten the distance of electron movement, reduce the internal resistance of the battery, enable faster charging speed, and the battery can support higher-rate charging and discharging; it can also reduce the risk of local overheating of the battery and improve the overall performance of the battery.

[0051] It can be understood that in another embodiment, along the length direction of the electrode plate 1, the tab connection area is arranged at one end of the electrode plate body. Specifically, one end of the electrode plate along the length direction of the electrode plate 1 has an empty foil area, and the tab is fixed in the empty foil area through the first adhesive layer.

[0052] In one embodiment, on the same side of the length direction of the electrode tab 1, the distance L3 between the edge of the first adhesive layer 104 and the edge of the tab connection area is 0 - 8 mm; along the width direction of the electrode tab 1, the distance L4 between the edge of the first adhesive layer 104 and the edge of the tab connection area close to the edge of the first adhesive layer 104 is 0 - 8 mm.

[0053] Furthermore, if the first adhesive layer covers the active material layer of the electrode tab body, it will increase the thickness of the electrode tab and reduce the volumetric energy density of the battery; if the distance between the edge of the first adhesive layer 104 and the edge of the tab connection area is too far, assuming the size of the tab connection area is fixed, then the size of the first adhesive layer is bound to be reduced. When the size of the first adhesive layer becomes smaller, the bonding area between the tab and the current collector will also decrease, which will further lead to an increase in resistance.

[0054] Therefore, by controlling L3 and L4 within the range of 0 - 8 mm, on the one hand, it will not affect the thickness of the electrode tab and ensure the energy density of the battery, and on the other hand, it will ensure the bonding area between the tab and the current collector, reduce the resistance, and improve the efficiency of current transmission.

[0055] Preferably, L3 is 0 mm, 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm or within the range composed of any two of the above values. L4 is 0 mm, 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm or within the range composed of any two of the above values.

[0056] In one embodiment, the size L1 of the through hole 1033 in the length direction of the electrode tab 1 is 50 μm - 2000 μm, and the size L2 of the through hole 1033 in the width direction of the electrode tab 1 is 50 μm - 2000 μm.

[0057] Furthermore, the size of the through hole 1033 should neither be too large nor too small. If the size of the through hole 1033 is too large, the structural strength of the tab 103 will be reduced, and thus the tab 103 is likely to break or deform during the battery process; if the size of the through hole 1033 is too small, the contact area between the first adhesive layer 104 and the tab 103 will be too small, which will affect the heat dissipation capacity and also the bonding strength between the tab and the first adhesive layer and the current collector.

[0058] Therefore, the size L1 of the through hole 1033 in the length direction of the electrode tab 1 is 50 μm - 2000 μm, and the size L2 of the through hole 1033 in the width direction of the electrode tab 1 is 50 μm - 2000 μm, which can not only ensure the structural strength of the tab 103, but also ensure sufficient heat dissipation capacity and the bonding strength between the tab and the first adhesive layer and the current collector.

[0059] Preferably, the size L1 of the through hole 1033 in the length direction of the electrode tab 1 is 50μm, 60μm, 70μm, 80μm, 90μm, 100μm, 200μm, 300μm, 400μm, 500μm, 600μm, 700μm, 800μm, 900μm, 1000μm, 1100μm, 1200μm, 1300μm, 1400μm, 1500μm, 1600μm, 1700μm, 1800μm, 1900μm, 2000μm or within the range formed by any two of the above values, and the size L2 of the through hole 1033 in the width direction of the electrode tab 1 is 50μm, 60μm, 70μm, 80μm, 90μm, 100μm, 200μm, 300μm, 400μm, 500μm, 600μm, 700μm, 800μm, 900μm, 1000μm, 1100μm, 1200μm, 1300μm, 1400μm, 1500μm, 1600μm, 1700μm, 1800μm, 1900μm, 2000μm or within the range formed by any two of the above values.

[0060] In one embodiment, as Figure 3 shown, along the thickness direction of the electrode tab 1, the projected area S1 of the through hole 1033 on the first surface of the current collector 101 and the projected area S2 of the connecting portion 1031 on the first surface satisfy: 0.1 ≤ S1 / S2 ≤ 0.8.

[0061] Furthermore, S1 / S2 should neither be too large nor too small. If S1 / S2 is too large, the area of the through hole 1033 is large, reducing the structural strength of the tab 103. The tab 103 is prone to breakage or even fracture, thereby weakening its current extraction performance and reducing the battery cycle performance. If S1 / S2 is too small, the area of the through hole 1033 is small, and the contact area between the first adhesive layer 104 and the tab 103 is too small, thereby affecting the heat dissipation capacity.

[0062] Therefore, S1 / S2 being 0.1 - 0.8 can not only ensure the structural strength of the tab 103, making the tab 103 not easily bend, but also ensure sufficient heat dissipation capacity.

[0063] Preferably, S1 / S2 is 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8 or within the range formed by any two of the above values.

[0064] In one embodiment, along the thickness direction of the tab 103, the connecting portion 1031 has a third surface facing the current collector 101. A non-through hole that does not penetrate the connecting portion 1031 along the thickness direction of the tab 103 is formed on the third surface. The depth of the non-through hole is less than the thickness of the tab 103. The non-through hole forms a concave portion on the third surface. The connecting portion 1031 has a fourth surface away from the current collector 101, and the fourth surface has a convex portion corresponding to the concave portion. The through hole facilitates the rapid volatilization and curing of the first adhesive layer 104, improving the curing efficiency and reliability. The non-through hole can increase the contact area between the tab 103 and the first adhesive layer 104, improving the conductivity while taking into account the strength of the tab 103.

[0065] Further, the concave portion is formed by stamping or the like. After stamping the third surface of the connecting portion 1031, a concave portion is formed on the third surface and a convex portion is formed on the fourth surface. By manufacturing the tab by stamping, the production efficiency is high and the cost is reduced.

[0066] In one embodiment, as Figure 7 and Figure 8 shown, on the side of the connecting portion 1031 facing the current collector 101, a protrusion 1034 is formed at the edge of the through hole 1033. The height h of the protrusion 1034 along the thickness direction of the electrode sheet 1 is 6 μm - 59 μm. The protrusion 1034 can not only enhance the structural strength of the tab 103, but also increase the bonding area between the first adhesive layer 104 and the tab 103, thereby improving the bonding force between the tab 103 and the current collector 101.

[0067] Preferably, h is 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 59 μm or within the range composed of any two of the above values.

[0068] In one embodiment, at least part of the protrusion 1034 is in contact with the current collector 101. The direct contact between the protrusion 1034 and the current collector 101 can improve the electrical conduction ability between the tab 103 and the current collector 101, thereby improving the current transmission efficiency.

[0069] In one embodiment, as Figures 2 to 6 shown, the shape of the through hole 1033 is circular, oval, linear or polygonal, etc. Specifically, the polygon is a rectangle, a rhombus, etc., and the linear shape is a straight line or an arc, etc.

[0070] In one embodiment, as Figure 1 、 Figure 2 、 Figure 9 and Figure 10As shown, the thickness T1 of the connecting portion 1031 is less than the thickness T of the protruding portion 1032. A first adhesive layer 104 is provided between the connecting portion 1031 and the current collector 101, and a through hole 1033 is provided on the connecting portion 1031. The thinner connecting portion 1031 results in a smaller thickness after the connecting portion 1031 is connected to the current collector 101, which can reduce the influence of the thickness of the tab 103 on the thickness of the battery cell, thereby improving the battery energy density.

[0071] In one embodiment, the thickness T1 of the connecting portion 1031 and the thickness T of the protruding portion 1032 satisfy: 20% ≤ T1 / T ≤ 90%; the thickness T1 of the connecting portion 1031 is 30 μm - 100 μm.

[0072] Furthermore, neither T1 / T nor T1 can be too large or too small. If the thickness of the connecting portion 1031 is too small, the strength of the tab 103 is insufficient and it is easy to bend; if the thickness of the connecting portion 1031 is too thick, it cannot play the role of reducing the battery thickness.

[0073] Therefore, when T1 / T is in the range of 20% - 90% and T1 is 30 μm - 100 μm, on the one hand, it ensures the strength of the tab 103 and prevents the risk of tab breakage caused by low strength due to too thin tabs. On the other hand, it can reduce the influence of the thickness of the tab 103 on the thickness of the battery cell, thereby improving the battery energy density.

[0074] Preferably, T1 / T is 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90% or within the range composed of any two of the above values. T1 is 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm or within the range composed of any two of the above values.

[0075] In one embodiment, the first adhesive layer 104 is a conductive adhesive layer. The first adhesive layer 104 includes conductive fillers and polymer fillers. Based on the mass of the first adhesive layer 104, the mass ratio of the conductive fillers is 60% - 95%, and the mass ratio of the polymer fillers is 3% - 40%. By controlling the mass ratio of the conductive fillers within a suitable range, the conductivity of the first adhesive layer can be ensured, the resistance can be significantly reduced, and the current transmission efficiency can be improved. And by controlling the mass ratio of the polymer fillers within a suitable range, the adhesion of the first adhesive layer can be ensured, the structural strength of the first adhesive layer can be enhanced, and damage caused by external impact can be prevented.

[0076] Preferably, the mass ratio of the conductive filler is 60%, 61%, 62%, 63%, 64%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95% or within the range composed of any two of the above values, and the mass ratio of the polymer filler is 3%, 5%, 6%, 7%, 8%, 9%, 10%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40% or within the range composed of any two of the above values.

[0077] Furthermore, the conductive filler includes at least one of gold powder, silver powder, copper powder, aluminum powder, nickel powder, carbon black, graphite, carbon nanotubes, graphene, and the polymer filler includes at least one of epoxy resin, silicone resin, polyimide resin, phenolic resin, polyolefin, styrene-butadiene rubber, polystyrene, polymethyl methacrylate.

[0078] It should be noted that the mass ratio of the conductive filler refers to the ratio of the mass of the conductive filler to the total mass of the first adhesive layer 104, and the mass ratio of the polymer filler refers to the ratio of the mass of the polymer filler to the total mass of the first adhesive layer 104.

[0079] In one embodiment, the first adhesive layer 104 further includes a support body, and the support body includes SiO 2 , Al 2 O 3 , ZrO 2 , polymer particles, mesophase carbon microspheres, carbides, titanium nitride, tin, tin-bismuth alloy, etc. At least one of them, and the particle size of the support body is larger than that of the conductive filler. When the tab 103, the first adhesive layer 104 and the tab body are bonded together under pressure, the support body will play a supporting role, that is, when the tab 103, the first adhesive layer 104 and the current collector are bonded together under pressure, it is ensured that most of the first adhesive layer 104 is located between the tab 103 and the tab body, which can prevent a large amount of the first adhesive layer 104 from being squeezed out beyond the positive projection of the tab 103 in the tab connection area, thereby reducing the conductive ability and bonding strength between the tab 103 and the tab body, making the ultimate tab of the battery including this tab prone to fall off under external force, increasing the internal resistance of the battery, and reducing the electrical performance of the battery.

[0080] Furthermore, the polymer particles are made of PP or PE, etc.

[0081] In one embodiment, based on the mass of the first adhesive layer 104, the mass ratio of the support body is 1% to 10%.

[0082] It should be noted that the mass ratio of the support body refers to the ratio of the mass of the support body to the total mass of the first adhesive layer 104.

[0083] Furthermore, the mass ratio of the support body should neither be too large nor too small. If the mass ratio of the support body is too large, the mass ratios of the conductive filler and the polymer filler are relatively small, which will affect the conductivity and bonding ability between the tab 103 and the electrode sheet body; if the mass ratio of the support body is too small, a large amount of the first adhesive layer 104 will be extruded and overflowed, which will also reduce the conductivity and bonding force between the tab 103 and the electrode sheet body.

[0084] Preferably, the mass ratio of the support body is 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10% or within the range composed of any two of the above values.

[0085] Therefore, the mass ratio of the support body is 1% to 10%, which ensures the conductivity and bonding ability between the tab 103 and the electrode sheet body, thereby improving the current transmission efficiency and the connection strength between the tab 103 and the electrode sheet body.

[0086] In one embodiment, the shape of the support body is spherical or ellipsoidal, and the particle size of the support body is 5 μm to 30 μm.

[0087] Furthermore, the particle size of the support body should neither be too large nor too small. If the particle size of the support body is too large, the thickness of the first adhesive layer 104 is too large, and the thickness after the tab 103 is connected to the current collector 101 is relatively large, which will increase the ineffective thickness of the battery cell and result in a decrease in the energy density of the battery. At the same time, if the particle size of the support body is too large, it will affect the effective connection between the conductive particles in the first adhesive layer, resulting in an insufficiently tight connection network and too large a resistance of the tab, deteriorating the cycle performance of the battery; if the particle size of the support body is too small, it cannot play a supporting role, and it is easy to cause the first adhesive layer 104 to flow too much when the tab 103, the first adhesive layer 104, and the electrode sheet body are bonded together under pressure, reducing the connection stability between the tab and the electrode sheet body.

[0088] Therefore, the particle size of the support body is 5 μm to 30 μm, which can reduce the influence of the thickness of the first adhesive layer 104 on the thickness of the battery cell while ensuring the supporting ability of the support body, that is, improving the energy density and cycle performance of the battery while ensuring the connection stability of the tab.

[0089] Preferably, the particle size of the support is 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, 11μm, 12μm, 13μm, 14μm, 15μm, 16μm, 17μm, 18μm, 19μm, 20μm, 21μm, 22μm, 23μm, 24μm, 25μm, 26μm, 27μm, 28μm, 29μm, 30μm or within the range formed by any two of the above values.

[0090] In one embodiment, the thickness of the first adhesive layer 104 is 3μm to 50μm.

[0091] Furthermore, the thickness of the first adhesive layer 104 should neither be too large nor too small. If the thickness of the first adhesive layer 104 is too large, the thickness after the tab 103 is connected to the current collector 101 is relatively large, which affects the thickness of the battery cell; if the thickness of the first adhesive layer 104 is too small, the conductivity and adhesion between the tab 103 and the electrode sheet body are reduced.

[0092] Therefore, the thickness of the first adhesive layer 104 is 3μm to 50μm. On the one hand, it reduces the influence of the thickness of the first adhesive layer 104 on the thickness of the battery cell and improves the energy density; on the other hand, it ensures the conductivity and adhesion between the tab 103 and the electrode sheet body, thereby improving the current transmission efficiency and the connection strength between the tab 103 and the electrode sheet body.

[0093] In one embodiment, the thickness T of the tab 103 and the thickness t of the first adhesive layer 104 satisfy: 0.6 ≤ T / t ≤ 50.

[0094] Furthermore, T / t should neither be too large nor too small. If T / t is too large, the conductivity and adhesion between the tab 103 and the electrode sheet body are reduced; if T / t is too small, the structural strength of the tab 103 is reduced, and the tab 103 is prone to bending, thereby affecting the performance of the battery.

[0095] Therefore, for T / t being 0.6 - 50, not only the conductivity and adhesion between the tab 103 and the electrode sheet body are ensured, but also the structural strength of the tab 103 is guaranteed, making the tab 103 not easily bend.

[0096] Preferably, T / t is 0.6, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50 or within the range formed by any two of the above values.

[0097] In one embodiment, as Figure 1As shown, along the width direction of the electrode tab, the current collector 101 has an edge 1013 close to the tab groove 1021. Along the width direction of the electrode tab, the distance D1 between one side of the first adhesive layer 104 close to the edge 1013 and the edge 1013 is 0.2 mm - 2 mm. The setting of D1 enables the first adhesive layer 104 to have a certain distance from the edge of the electrode tab 1, preventing the first adhesive layer 104 provided on the electrode tab 1 in the battery from contacting the coating on another electrode tab with the opposite polarity, avoiding the risk of short circuit and improving the battery safety.

[0098] Preferably, D1 is 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1 mm, 1.1 mm, 1.2 mm, 1.3 mm, 1.4 mm, 1.5 mm, 1.6 mm, 1.7 mm, 1.8 mm, 1.9 mm, 2 mm or within the range composed of any two of the above values.

[0099] In one embodiment, along the thickness direction of the electrode tab 1, the projected area S2 of the connecting portion 1031 on the first surface and the projected area S3 of the first adhesive layer 104 on the first surface satisfy: 20% ≤ S2 / S3 ≤ 150%.

[0100] Furthermore, S2 / S3 should neither be too large nor too small. If S2 / S3 is too small, when the value of S2 is too small, due to the small contact area between the tab and the current collector, the internal resistance of the battery will increase and the bonding strength will decrease; if S2 / S3 is too large, when the value of S2 is too large, the first adhesive layer cannot completely cover the connecting portion, resulting in insecure bonding between the tab and the current collector and prone to the risk of loosening or falling off.

[0101] Therefore, S2 / S3 is 20% - 150%, ensuring that the first adhesive layer 104 and the tab 103 and the current collector 101 have sufficient bonding area, enhancing the bonding strength, reducing the internal resistance of the battery, and improving the electrical conduction ability.

[0102] Preferably, S2 / S3 is 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 100, 110%, 120%, 130%, 140%, 150% or within the range composed of any two of the above values.

[0103] In one embodiment, as Figure 1 and Figure 2As shown, a connecting member 108 is provided on a portion of the first adhesive layer 104 that extends beyond the connecting portion 1031. The connecting member 108 can protect the first adhesive layer 104 from being corroded by the electrolyte or reduce the contact area between the first adhesive layer 104 and the electrolyte, preventing side reactions between the first adhesive layer 104 and the electrolyte. It can also prevent the first adhesive layer 104 from overflowing and covering the active material layer near the ear groove 1021 after the first adhesive layer 104 is hot-pressed together with the ear 103, reducing the energy density.

[0104] Furthermore, the connecting member 108 is made of pressure-sensitive adhesive, thermosetting adhesive, etc.

[0105] In one embodiment, as Figure 1 and Figure 2 shown, a first insulating member 105 is provided on a side of the connecting portion 1031 away from the current collector 101. The first insulating member 105 can further fix the ear 103 and the first adhesive layer 104, preventing the first adhesive layer 104 from swelling after leaking out and contacting the electrolyte, which would increase the internal resistance of the first adhesive layer 104 and fail to ensure the conductive effect.

[0106] Furthermore, the first insulating member 105 is made of insulating materials such as adhesive tape. The projection of the first insulating member along the thickness direction of the electrode plate completely covers the first adhesive layer. It can be understood that in some embodiments, the first insulating member 105 may not be provided.

[0107] In the related art, double-sided empty foil areas are usually provided between the ear and the electrode plate body to achieve electrical connection, but the setting of the double-sided empty foil areas reduces the active coating area of the electrode plate body, which is not conducive to improving the energy density of the battery.

[0108] In one embodiment, as Figure 1 and Figure 2 shown, the current collector 101 has a first surface and a second surface that are oppositely arranged; the electrode plate body further includes: a first active material layer 102 and a second active material layer 106. The first active material layer 102 is provided on the first surface, and an ear groove 1021 is provided on the first active material layer 102. The current collector 101 includes a single-sided empty foil area, and the first surface of the single-sided empty foil area is exposed in the ear groove 1021; the second active material layer 106 is provided on the second surface, and the area of the second surface opposite to the single-sided empty foil area is covered by the second active material layer 106. The single-sided empty foil area forms an ear connection area, and the connecting portion 1031 is connected to the single-sided empty foil area. By only providing a single-sided empty foil area, the electrical connection between the ear 103 and the current collector 101 in the empty foil area can also be achieved, retaining the active coating on the back of the empty foil area, thereby improving the energy density of the battery.

[0109] According to an embodiment of the present invention, on the other hand, a battery is further provided, which includes a separator 3 and at least two polar opposite electrode plates. The at least two polar opposite electrode plates are respectively a positive electrode plate 2 and a negative electrode plate 4. The positive electrode plate 2, the separator 3 and the negative electrode plate 4 are stacked and wound. At least one of the positive electrode plate 2 and the negative electrode plate 4 is the above-mentioned electrode plate 1. When the positive electrode plate 2 is the above-mentioned electrode plate 1, the electrode tab 103 is a positive electrode tab 203, and the current collector is a positive current collector 201. When the negative electrode plate 4 is the above-mentioned electrode plate 1, the electrode tab 103 is a negative electrode tab 403, and the current collector is a negative current collector 401.

[0110] Further, the active material layer of the positive electrode plate 2 is a positive active material layer 202, the current collector 101 of the positive electrode plate 2 is a positive current collector 201, the active material layer of the negative electrode plate 4 is a negative active material layer 402, and the current collector 101 of the negative electrode plate 4 is a negative current collector 401.

[0111] In one embodiment, as Figures 11 to 14 shown, both the positive electrode plate 2 and the negative electrode plate 4 are the above-mentioned electrode plate 1. The positive electrode plate 2 includes a positive current collector 201 and a positive active material layer 202 provided on the surface of the positive current collector 201. The positive electrode plate 2 includes a first groove 204. The thickness of the positive active material layer 202 in the first groove 204 is less than the thickness of the positive active material layer 202 in other regions of the positive electrode plate 2 except the first groove 204. Along the thickness direction of the battery, the first groove 204 is disposed opposite to the negative electrode tab 403, and the positive projection of the negative electrode tab 403 in the thickness direction of the battery is located in the first groove 204. The setting of the first groove 204 can save the thickness accumulation of the negative electrode tab 403, reduce the battery thickness, and thus improve the battery energy density.

[0112] Further, the negative electrode plate 4 includes a negative current collector 401 and a negative active material layer 402 provided on the surface of the negative current collector 401. The negative electrode plate 4 includes a second groove 404 formed by the absence or thinning of the negative active material layer 402. Along the thickness direction of the battery, the second groove 404 is disposed opposite to the positive electrode tab 203, and the positive projection of the positive electrode tab 203 in the thickness direction of the battery is located in the second groove 404. The setting of the second groove 404 can save the thickness accumulation of the positive electrode tab 203, reduce the battery thickness, and thus improve the battery energy density.

[0113] Further, a second insulating member 205 is provided on the side of the positive electrode sheet 2 facing the negative electrode tab 403, and the second insulating member 205 at least partially covers the first groove 204. A third insulating member 405 is provided on the side of the negative electrode sheet 4 facing the positive electrode tab 203, and at least a portion of the third insulating member 405 covers the second groove 404. The second insulating member 205 prevents lithium ions on the positive electrode sheet 2 facing the negative electrode tab 403 from entering the negative electrode tab area during charging to cause lithium deposition. The third insulating member can prevent the positive electrode tab 203 from contacting the negative electrode sheet 4, avoiding the risk of short circuit caused by positive and negative electrode contact due to manufacturing defects, external impact, or material expansion during long-term use, thereby improving battery safety, extending battery life, and improving battery performance.

[0114] Specifically, as Figure 13 shown, the second insulating member 205 partially covers the first groove 204, or, as Figure 14 shown, the second insulating member 205 completely covers the first groove 204 and extends from the opening of the first groove 204 to the surface of the positive electrode active material layer 202.

[0115] In one embodiment, a portion of the protruding portion 1032 of the electrode tab 103 forms a sealing portion, and a sealing member 107 is provided at the sealing portion. The sealing member 107 functions to seal, preventing electrolyte leakage and the entry of external moisture, oxygen, etc. into the battery interior.

[0116] The following further describes the present application in detail with specific embodiments, and these embodiments should not be construed as limiting the scope claimed by the present application. For those in which specific experimental steps or conditions are not indicated in the embodiments and comparative examples, the operations or conditions of the conventional experimental steps described in the literature in this field can be followed. In all embodiments and comparative examples of the present application, the unit % represents mass percentage.

[0117] The method for preparing a battery includes:

[0118] (1) Prepare a negative electrode sheet: uniformly coat the prepared negative electrode slurry on a copper foil, dry it at 100 °C, and perform rolling and slitting to obtain a negative electrode sheet;

[0119] (2) Prepare a positive electrode sheet: uniformly coat the prepared positive electrode slurry on an aluminum foil to form a positive electrode sheet;

[0120] (3) Prepare a separator:

[0121] (4) Wind the positive electrode sheet, separator, and negative electrode sheet to obtain an electrode core, and then make a battery through steps such as encapsulation, liquid injection, formation, secondary encapsulation, and grading.

[0122] Prepare batteries according to the parameters in Table 1 and Table 2, and perform electrical performance tests on the batteries prepared in each embodiment and comparative example. The test methods for the batteries include:

[0123] 1. Battery temperature rise test method:

[0124] Let the battery stand still for 5 minutes, then charge it at a constant current of 2.5C until 4.3V, switch to a constant current of 2C and charge until 4.45V, then switch to a constant voltage of 1.5C and charge until 4.58V, with the cut-off current being 0.05C. During the charging process, record the temperatures of the positions near the left and right tabs of the battery body and the environment. The maximum temperature difference between the battery body temperature and the environment is the temperature rise of the battery.

[0125] 2. Bonding strength test method:

[0126] Cut out the electrode sheet with tabs, that is, the cutting position is more than 5 mm away from the edge of the tab groove. Then cover and protect the coating on the back of the tab groove with transparent tape. Use a tensile tester to clamp the coated part covered with tape, and clamp the tab at the upper end. Zero the tensile tester, and finally click to pull upward until the tab separates from the tab groove of the electrode plate, and read the tensile value.

[0127] 3. Capacity retention rate test method:

[0128] Place the battery on the fixture of the charge and discharge cycle tester. Under an environment of 25°C, charge it at a constant current of 2.5C to 4.3V, charge it at a constant current of 1.5C until 4.4V, then switch to a constant voltage of 1.2C and charge until 4.5V (0.2C, cut-off current 0.05C), and then discharge it at a constant current of 1.5C until 3.4V, then switch to a constant current of 0.5C and discharge until 3V. Charge and discharge in cycles 1000 times in sequence, and then record the ratio of the discharge capacity of the 1000th time to the discharge capacity of the 1st time as the capacity retention rate.

[0129] 4. ED test method:

[0130] Charge the battery at a current of 0.2C to 4.5V, then charge it at a constant voltage until the current drops to 0.02C, and then discharge it at a current of 0.2C until 3.0V. The energy of the discharge is recorded as E; measure the thickness, width and length of the battery and calculate the product of the three to obtain the volume of the battery, which is recorded as V. The calculation formula for the volume energy density VED is VED = E / V.

[0131] 5. Test method for the thermal conductivity of the first adhesive layer:

[0132] 1) Disassemble the battery and take out the sample of the first adhesive layer in the battery, and measure the area s and thickness d of the sample of the first adhesive layer;

[0133] 2) Use a steady-state thermal conductivity meter to set the applied pressure to 50N, set the cold plate temperature to 25°C, and set the hot plate temperature to 65°C;

[0134] 3) Start the equipment to start the test, and record the steady-state heat flow Q and the temperature difference ΔT;

[0135] 4) Calculate the thermal conductivity λ = (Q × d) / (s × ΔT) according to the formula.

[0136] Please refer to Table 1 and Table 2 for the above test results.

[0137] Table 1 Structural and Performance Parameters of the Battery

[0138]

[0139]

[0140] Table 2 Parameters and Performance Parameters of the Support of the Battery

[0141]

[0142] It should be noted that " / " in Table 1 indicates non - existence. In Examples 1 - 1 to 4 - 5, the mass ratio of the support is 5%, the particle size of the support is 15 μm. In Examples 5 - 1 to 6 - 4, the thermal conductivity is 25 W / (m·K), both L1 and L2 are 750 μm, S1 is 26.49375, S2 is 84, and S3 is 112.

[0143] It can be seen from Table 1 that:

[0144] Compared with Examples 1 - 1 to 1 - 4, in Comparative Example 1, when the thermal conductivity of the conductive adhesive is out of range and too small, even if through - holes are provided on the connecting part, the temperature rise of the battery during charge and discharge increases significantly to 30.2 °C, affecting the cycle performance of the battery; in Comparative Example 2, no through - holes are provided on the connecting part. Even if the thermal conductivity is reasonable, the temperature rise of the battery during charge and discharge increases to 28.9 °C, affecting the cycle performance of the battery. Thus, by controlling the thermal conductivity and through - holes within an appropriate range and shortening the curing time, the temperature rise of the battery during charge and discharge is lower, improving the cycle performance of the battery.

[0145] In Example 2 - 1, when L1 and L2 of the through - hole take the lower limit values, the temperature rise of the battery during charge and discharge is lower, and the bonding strength of the tab is smaller; in Example 3 - 1, when L1 and L2 of the through - hole take the upper limit values, compared with Example 2 - 1, the temperature rise of the battery is slightly higher, and the cycle performance of the battery is slightly worse; in Example 2 - 3, when L1 of the through - hole takes the lower limit value and L2 takes the lower limit value, Example 2 - 3 only increases in size in the L2 direction compared with Example 2 - 1, and the effect is also slightly worse. Thus, by controlling L1 and L2 of the through - hole within an appropriate range and shortening the curing time, the temperature rise and cycle performance of the battery are improved.

[0146] In Example 3-2, when the via hole area is too small, since the heat dissipation is slow during the curing of the conductive adhesive, the curing time is too long, the temperature rise of the battery is slightly higher during charge and discharge, the bonding strength of the tab is also small, and the cycle performance of the battery is slightly poor; in Example 3-1, when the via hole area is too large, the bonding strength of the tab is also small, and the cycle performance of the battery is slightly poor. Thus, by keeping S1 / S2 within a suitable range, the curing time is shortened, and the temperature rise and cycle performance of the battery are improved.

[0147] In Example 4-1, when the value of S2 is too small, since the contact area between the tab and the current collector is small, the temperature rise of the battery is slightly higher during charge and discharge, and the cycle performance of the battery is slightly poor. Thus, by controlling S2 / S3 within a suitable range, the contact area between the tab and the current collector is ensured, and the temperature rise and cycle performance of the battery are improved.

[0148] As can be seen from Table 2:

[0149] In Example 5-4, when the proportion of the support body is too large, the temperature rise of the battery is high during charge and discharge, and the cycle performance of the battery is slightly poor. Thus, by controlling the proportion of the support body within a suitable range, the temperature rise and cycle performance of the battery are improved.

[0150] In Example 6-4, when the particle size of the support body is too large, the temperature rise of the battery is high during charge and discharge, and the cycle performance of the battery is slightly poor. Thus, by controlling the particle size of the support body within a suitable range, the temperature rise and cycle performance of the battery are improved.

[0151] Although the embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations fall within the scope defined by the appended claims.

Claims

1. A pole piece, characterized in that: include: A pole piece body, comprising a current collector (101), wherein the pole piece body has a pole ear connection area; A pole lug (103) having a connection portion (1031) connected to the pole lug connection region and an extension portion (1032) extending out of the edge of the pole piece body; A first adhesive layer (104) is arranged in the electrode tab connection region, and along the thickness direction of the electrode tab (103), the first adhesive layer (104) is located between the connection portion (1031) and the current collector (101) in the electrode tab connection region, the connection portion (1031) is provided with a through hole (1033) penetrating the electrode tab (103) along the thickness direction of the electrode tab (103), at least a portion of the first adhesive layer (104) is embedded in the through hole (1033), and the thermal conductivity of the first adhesive layer (104) is 1.5 W / (m·K)-50 W / (m·K).

2. The pole piece according to claim 1, characterized in that: Along the length direction of the pole piece (1), the pole ear connection area is arranged in the middle of the pole piece body; and / or, located on the same side of the length direction of the pole piece (1), a distance L3 between the edge of the first adhesive layer (104) and the edge of the pole tab connection area is 0-8 mm; and / or, along the width direction of the pole piece (1), a distance L4 between an edge of the first adhesive layer (104) and an edge of the pole lug connection region close to the edge of the first adhesive layer (104) is 0-8 mm; And / or, a dimension L1 of the through hole (1033) in the length direction of the pole piece (1) is 50 μm-2000 μm; And / or, a dimension L2 of the through hole (1033) in the width direction of the pole piece (1) is 50 μm-2000 μm; and / or, along the thickness direction of the pole piece (1), a projection area S1 of the through hole (1033) on the first surface of the current collector (101) and a projection area S2 of the connecting portion (1031) on the first surface satisfy: 0.1≤S1 / S2≤0.8; And / or, the through hole (1033) is in the shape of a circle, an ellipse, a line or a polygon.

3. The pole piece according to claim 1, characterized in that: The current collector (101) has a first surface and a second surface that are arranged opposite to each other; The pole piece body also includes: A first active material layer (102) is arranged on the first surface, a tab groove (1021) is arranged on the first active material layer (102), the current collector (101) comprises a single-sided empty foil area, the first surface of the single-sided empty foil area is exposed to the tab groove (1021); a second active material layer (106) is arranged on the second surface, an area of ​​the second surface opposite to the single-sided empty foil area is covered by the second active material layer (106), the single-sided empty foil area forms the tab connection area, and the connection portion (1031) is connected to the single-sided empty foil area.

4. The pole piece according to claim 1, characterized in that: Along the thickness direction of the pole lug (103), the connecting portion (1031) has a third surface facing the current collector (101), and a non-through hole that does not penetrate the connecting portion (1031) along the thickness direction of the pole lug (103) is opened on the third surface, and the depth of the non-through hole is less than the thickness of the pole lug (103), and the non-through hole forms a recess on the third surface, and the connecting portion (1031) has a fourth surface away from the current collector (101), and the fourth surface has a convex portion corresponding to the recess.

5. The pole piece according to claim 1, characterized in that: On the side of the connecting portion (1031) facing the current collector (101), a protrusion (1034) is formed on the edge of the through hole (1033), and the height h of the protrusion (1034) along the thickness direction of the pole piece (1) is 6 μm-59 μm; And / or, at least a portion of the protrusions (1034) are in contact with the current collector (101).

6. The pole piece according to claim 1, characterized in that: The thickness T1 of the connecting portion (1031) is smaller than the thickness T of the extending portion (1032); And / or, the thickness T1 of the connecting portion (1031) and the thickness T of the extending portion (1032) satisfy: 20%≤T1 / T≤90%; And / or, the thickness T1 of the connecting portion (1031) is 30 μm-100 μm.

7. The pole piece according to claim 1, characterized in that: The first adhesive layer (104) is a conductive adhesive layer, and the first adhesive layer (104) comprises a conductive filler and a polymer filler; Based on the mass of the first adhesive layer (104), the mass of the conductive filler accounts for 60%-95%, and the mass of the polymer filler accounts for 3%-40%; And / or, the conductive filler includes at least one of gold powder, silver powder, copper powder, aluminum powder, nickel powder, carbon black, graphite, carbon nanotubes, and graphene, and the polymer filler includes at least one of epoxy resin, silicone resin, polyimide resin, phenolic resin, polyolefin, styrene-butadiene rubber, polystyrene, and polymethyl methacrylate.

8. The pole piece according to claim 7, characterized in that: The first adhesive layer (104) further includes a support, the support including at least one of SiO2, Al2O3, ZrO2, polymer particles, mesocarbon microspheres, carbides, titanium nitride, tin, and tin-bismuth alloy, and / or the particle size of the support is larger than the particle size of the conductive filler.

9. The pole piece according to claim 8, characterized in that: Based on the mass of the first adhesive layer (104), the mass of the support body accounts for 1% to 10%; And / or, the support body is spherical or ellipsoidal in shape; and / or, the particle size of the support is 5 μm to 30 μm; And / or, the thickness of the first adhesive layer (104) is 3 μm to 50 μm; And / or, the thickness T of the tab (103) and the thickness t of the first adhesive layer (104) satisfy: 0.6≤T / t≤50.

10. The pole piece according to claim 1, characterized in that: Along the width direction of the pole piece, the current collector (101) has an edge (1013) close to the protruding portion (1032); along the width direction of the pole piece, a distance D1 between a side of the first adhesive layer (104) close to the edge (1013) and the edge (1013) is 0.2 mm-2 mm; And / or, along the thickness direction of the pole piece (1), a projection area S2 of the connecting portion (1031) on the first surface of the current collector (101) and a projection area S3 of the first adhesive layer (104) on the first surface satisfy: 20%≤S2 / S3≤150%.

11. The pole piece according to claim 1, characterized in that: A connecting piece (108) is provided on the portion of the first adhesive layer (104) that exceeds the connecting portion (1031); And / or, a first insulating member (105) is provided on a surface of the connecting portion (1031) that is away from the current collector (101).

12. A battery, characterized in that: The invention comprises a separator (3) and at least two pole pieces with opposite polarities, wherein the at least two pole pieces with opposite polarities are respectively a positive pole piece (2) and a negative pole piece (4), wherein the positive pole piece (2), the separator (3) and the negative pole piece (4) are stacked and wound, and at least one of the positive pole piece (2) and the negative pole piece (4) is the pole piece (1) according to any one of claims 1 to 11; When the positive electrode sheet (2) is the electrode sheet (1) according to any one of claims 1 to 11, the electrode tab (103) is a positive electrode tab (203), and the current collector is a positive electrode current collector (201); And / or, when the negative electrode sheet (4) is the electrode sheet (1) according to any one of claims 1 to 11, the electrode tab (103) is a negative electrode tab (403), and the current collector is a negative electrode current collector (401).

13. The battery according to claim 12, characterized in that The positive electrode sheet (2) and the negative electrode sheet (4) are both the electrode sheets (1) according to any one of claims 1 to 11, the positive electrode sheet (2) comprises the positive electrode current collector (201) and a positive electrode active material layer (202) arranged on the surface of the positive electrode current collector (201), the positive electrode sheet (2) comprises a first groove (204), the thickness of the positive electrode active material layer (202) in the first groove (204) is less than the thickness of the positive electrode active material layer (202) in other areas of the positive electrode sheet (2) except the first groove (204), along the thickness direction of the battery, the first groove (204) is arranged opposite to the negative electrode ear (403), and the orthographic projection of the negative electrode ear (403) along the thickness direction of the battery is located in the first groove (204); And / or, the negative electrode sheet (4) comprises the negative electrode current collector (401) and a negative electrode active material layer (402) arranged on the surface of the negative electrode current collector (401), the negative electrode sheet (4) comprises a second groove (404) formed by the absence of the negative electrode active material layer (402), along the thickness direction of the battery, the second groove (404) is arranged opposite to the positive electrode ear (203), and the orthographic projection of the positive electrode ear (203) along the thickness direction of the battery is located in the second groove (404).

14. The battery according to claim 13, characterized in that When the positive electrode sheet (2) includes a first groove (204), a second insulating member (205) is provided on a side of the positive electrode sheet (2) facing the negative electrode ear (403), and the second insulating member (205) at least partially covers the first groove (204); And / or, when the negative electrode sheet (4) includes a second groove (404), a third insulating member (405) is provided on a side of the negative electrode sheet (4) facing the positive electrode ear (203), and at least a portion of the third insulating member (405) covers the second groove (404).

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