Battery and electric equipment

Abstract

The embodiment of the utility model provides a battery and electric equipment. The battery comprises a positive plate, a negative plate and a diaphragm, wherein the positive plate and the negative plate are laminated and wound into an electrode body through the diaphragm. The positive plate comprises a positive current collector, a positive active layer, a first positive tab, a second positive tab and protective glue, the starting end of the positive current collector is provided with a first empty foil area, the positive active layer is provided with a foil exposing groove for exposing the positive current collector, the first positive tab is electrically connected with the positive current collector in the first empty foil area, and the second positive tab is partially located in the foil exposing groove and electrically connected with the positive current collector; and the protective glue covers the part of the second positive tab in the foil exposing groove and does not cover the positive active layer. The negative plate comprises a negative current collector and a negative tab electrically connected with the negative current collector, the first positive tab and the negative tab form a charging and discharging circuit, a heating circuit formed by the first positive tab and the second positive tab provides working temperature for the charging and discharging circuit, and the first positive tab and the second positive tab are located at the starting end and the middle of the positive current collector, so that the thickness of the electrode body is not increased; and the energy density can be improved.

Description

TECHNICAL FIELD

[0001] The embodiment of the utility model relates to the field of battery, especially, relate to a battery and electric equipment. BACKGROUND

[0002] With the development of technology, people have higher requirements for the charging capacity and charge-discharge rate of lithium ion batteries. The low-temperature large-rate charging mode can shorten the charging time and thus improve the charging efficiency, which is the development trend of batteries. However, the use of lithium ion batteries at a lower temperature may have some problems, such as capacity decay, reduced charge-discharge efficiency, increased internal impedance of the battery, and even the possibility of metal lithium precipitation at the negative electrode position during large-rate fast charging.

[0003] To solve the problems of slow charging speed and easy lithium precipitation during large-rate charging of the battery at low temperature, the related technology provides various solutions, such as using low-temperature electrolyte, low-impedance positive electrode formula, and higher-rate negative electrode material, and reducing the compaction of the positive and negative electrodes and the surface density to shorten the ion transmission distance. However, the implementation of these solutions often involves an increase in cost and a loss of battery energy density, and the lithium precipitation problem still exists, which still needs to be alleviated by reducing the charging rate. SUMMARY

[0004] Therefore, the embodiments of the utility model provide a battery and electric equipment to solve the problem of easy lithium precipitation of the previous battery under the condition of low-temperature large-rate charging.

[0005] In one aspect, the embodiments of the utility model provide a battery. The battery includes a positive electrode sheet, a negative electrode sheet, and a separator. The positive electrode sheet and the negative electrode sheet are stacked and wound with the separator to form an electrode body. The electrode body includes two curved portions and a flat portion located between the two curved portions. The positive electrode sheet includes a positive current collector, a positive active layer, a first positive electrode tab, a second positive electrode tab, and a protective glue. The positive current collector has a first empty foil area at a starting end. The positive active layer has an exposed foil groove located at the flat portion and exposing the positive current collector. The first positive electrode tab is electrically connected to the positive current collector at the first empty foil area. The second positive electrode tab is partially located in the exposed foil groove and electrically connected to the positive current collector. The protective glue covers the part of the second positive electrode tab located in the exposed foil groove and does not cover the positive active layer. The negative electrode sheet includes a negative current collector and a negative electrode tab electrically connected to the negative current collector. The first positive electrode tab and the negative electrode tab are used to form a charge-discharge circuit, and the first positive electrode tab and the second positive electrode tab are used to form a heating circuit.

[0006] In one possible implementation, the second positive electrode tab includes a copper base and a nickel adhesion layer provided on at least part of the surface of the base. The second positive electrode tab is electrically connected to the positive current collector through the adhesion layer.

[0007] In a possible implementation, the second positive tab includes a first segment and a second segment along a width direction of the positive plate, an insulating adhesive is provided on an outer periphery of the second positive tab to separate the first segment and the second segment, the second segment is at least partially located in the exposed tab groove, and the adhesive layer covers a surface of the second segment and ends at the insulating adhesive.

[0008] In a possible implementation, 0.8 mm≤D1≤1.6 mm; and / or 0.3≤H2 / H1≤0.9; and / or 15 mm≤H1≤23 mm; and / or 5 mm≤H2≤10 mm, where D1 is an average distance from an edge of the second positive tab to an edge of the exposed tab groove, H1 is a size of a portion of the first positive tab that overlaps the positive current collector in a width direction of the positive plate, and H2 is a size of a portion of the second positive tab that overlaps the positive current collector in the width direction of the positive plate.

[0009] In a possible implementation, 3≤M≤N-3; and / or 1 / 10≤W2 / W1≤1 / 2; and / or 200 mm≤D2≤1900 mm, where the positive plate includes N flat segments in the flat portion, the second positive tab is located on an Mth flat segment from a starting end of the positive current collector among the N flat segments, W1 is a width of the flat portion, W2 is a distance from the second positive tab to a closer one of the two curved portions, and D2 is a distance between the first positive tab and the second positive tab in a length direction of the positive plate.

[0010] In a possible implementation, the negative plate further includes a negative active layer disposed on the negative current collector, a second empty tab area is provided at a starting end of the negative current collector, and the negative tab is electrically connected to the negative current collector at the second empty tab area.

[0011] In a possible implementation, an area of the second positive tab is less than or equal to an area of the first positive tab.

[0012] In a possible implementation, the positive plate satisfies 7 μm≤T1≤20 μm; 50 μm≤T2≤150 μm; and 6≤T2 / T1≤15. The first positive tab and the second positive tab are welded to the positive current collector, T1 is a thickness of the positive current collector, and T2 is a thickness of any one of the first positive tab and the second positive tab. The negative plate satisfies 3 μm≤T3≤20 μm; 50 μm≤T4≤150 μm; and 7≤T4 / T3≤18. The negative tab is welded to the negative current collector, T3 is a thickness of the negative current collector, and T4 is a thickness of the negative tab.

[0013] In a possible implementation, the positive plate satisfies R1>R2, and / or R1>R3, and / or R2>R3. R1 is a resistance value of a portion of the positive current collector between the first positive tab and the second positive tab, R2 is a resistance value of a portion where the first positive tab is welded to the positive current collector, and R3 is a resistance value of a portion where the second positive tab is welded to the positive current collector.

[0014] In another aspect, the embodiments of the utility model also provide a kind of electric equipment.The electric equipment includes the battery of preceding text, charging power supply or load, heating power supply, charge-discharge circuit, heating circuit, temperature sensor, controller.Charge-discharge circuit is used to connect the first positive lug with the positive pole of charging power supply or load, and negative lug is electrically connected with the negative pole of charging power supply or load.Heating circuit is used to connect the first positive lug with the positive pole of heating power supply, and the second positive lug is electrically connected with the negative pole of heating power supply, temperature sensor is used to sense the temperature of the electrode body, controller is connected with temperature sensor, and accepts the sensing result of temperature sensor, to connect or disconnect heating circuit and charge-discharge circuit according to sensing result.

[0015] According to the embodiments of the utility model, the first positive lug is located in the first empty foil area, and the second positive lug is located in the exposed foil groove, which can ensure that the first positive lug and the second positive lug are electrically connected with the positive pole and the negative pole of the heating power supply to form a heating circuit with large impedance, thereby providing appropriate working temperature for the charge-discharge circuit formed by the electrical connection of the first positive lug and the negative lug, thereby reducing the risk of lithium precipitation of the battery in the low-temperature large-rate charging state.In addition, the first positive lug is located at the starting end of the positive current collector, so that when the electrode body is wound, the first positive lug will be located inside the electrode body and will not form a protrusion on the outside of the electrode body, thereby helping to improve the energy density of the electrode body.In addition, the second positive lug is a heating lug, and the current density is small, so that when the protective glue covers the second positive lug, only the part located in the exposed foil groove can be covered without covering the positive active layer, which enables the thickness of the protective glue to be absorbed by the exposed foil groove, thereby not increasing the thickness of the electrode body after the electrode body is wound, which helps to improve the energy density. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 It is a structural schematic diagram of the battery according to an embodiment of the utility model.

[0017] Figure 2 It is a structural schematic diagram of the battery according to Figure 1 It is a structural schematic diagram of the wound electrode body of the battery in

[0018] Figure 3 It is a sectional view taken along the A-A line in Figure 2

[0019] Figure 4 It is an unfolded structure schematic diagram of the positive sheet and the negative sheet of the wound electrode body in Figure 3

[0020] Figure 5 It is a structural schematic diagram of the first positive lug in Figure 3

[0021] Figure 6 It is​​​Figure 3 Structure diagram of a second positive electrode tab.

[0022] Figure 7 Structure diagram of a power consuming device according to an embodiment of the present application DETAILED DESCRIPTION

[0023] Many specific details are set forth in this document to provide a thorough understanding of the overall structure, function, and use of the embodiments described and shown in the specification. Well-known operations, components, and elements are not described in detail to avoid obscuring the description of the application described in the specification. The reader will understand that the embodiments described and shown herein are non-limiting examples, and it will be recognized that the specific structural and functional details described herein can be representative and illustrative. Variations and changes can be made to these embodiments without departing from the scope of the claims.

[0024] A battery 100 according to an embodiment of the present application is shown in Figure 1 . Referring to Figure 1 , the battery 100 can include an electrode body 10 and a packaging body 20, the electrode body 10 being housed in the packaging body 20. For example, the electrode body 10 can be flat. The electrode body 10 is shown separately in Figure 2 , which can have a ratio of a dimension in a width direction to a dimension in a thickness direction of 1 to 200. In the drawings, the "width direction" of the electrode body 10 is indicated by arrow U, and the "thickness direction" of the electrode body 10 is indicated by arrow V.

[0025] By way of example only, the battery 100 can employ a pouch packaging. That is, the packaging body 20 can be an aluminum-plastic composite film. Of course, in other examples, the battery 100 can employ other packaging. For example, in some examples, the battery 100 can employ a square hard-shell packaging. As another example, in some examples, the electrode body 10 can be cylindrical, and correspondingly, the battery 100 can employ a cylindrical packaging.

[0026] Referring to Figures 2 to 4 , the electrode body 10 can be a jelly-roll electrode body, which can include a positive electrode sheet 11, a negative electrode sheet 12, and a separator 13 arranged in layers. The separator 13 is a member that insulates the positive electrode sheet 11 and the negative electrode sheet 12. The positive electrode sheet 11 and the negative electrode sheet 12 can be wound into the electrode body 10 with the separator 13 in between. The electrode body 10 includes two curved portions 141 and a flat portion 142 between the two curved portions 141.

[0027] Referring to Figure 3 and Figure 4 , the positive electrode sheet 11 can include a positive current collector 111 and a positive active layer 112 arranged in layers. The positive active layer 112 can be disposed on either side of the positive current collector 111 in the thickness direction. Correspondingly, continuing to refer to Figure 3 andFigure 4 The negative electrode sheet 12 includes a negative current collector 121 and a negative active layer 122 arranged in a stack. The negative active layer 122 can be arranged on either side of the negative current collector 121 in the thickness direction.

[0028] By way of example only, the positive current collector 111 can be a metal foil in a strip shape, and the positive active layer 112 can include a positive active material capable of reversibly absorbing and releasing charge carriers, and can further include a conductive material, a binder, and various additive components. By way of example only, the metal foil can be an aluminum foil, the positive active material can be a lithium nickel cobalt manganese composite oxide or the like lithium transition metal composite oxide, the conductive material can be a carbon-based material such as acetylene black, and the binder can be polyvinylidene fluoride or the like.

[0029] By way of example only, the negative current collector 121 can be a metal foil in a strip shape, and the negative active layer 122 can include a negative active material capable of reversibly absorbing and releasing charge carriers, a binder, a dispersant, and various additive components. By way of example only, the metal foil can be a copper foil, the negative active material can be a carbon-based material such as graphite, the binder can be a rubber-based material such as butadiene rubber, and the dispersant can be a cellulose-based material such as carboxymethyl cellulose.

[0030] Reference is made to Figure 4 The positive electrode sheet 11 can further include a first positive tab 151, a second positive tab 152, and a protective tape 16, and the negative electrode sheet 12 can further include a negative tab 153. The first positive tab 151 and the second positive tab 152 can be welded to the positive current collector 111, that is, both the first positive tab 151 and the second positive tab 152 can be hard tabs. The negative tab 153 can be electrically connected to the negative current collector 121, for example, welded together, or integrally formed.

[0031] Reference is made to Figure 3 and Figure 4The starting end of the positive current collector 111 is provided with a first empty foil area 113, the positive active layer 112 is provided with a foil exposure groove 114 located at the flat part 142 and exposing the positive current collector 111, the first positive electrode lug 151 is electrically connected with the positive current collector 111 at the first empty foil area 113, and the second positive electrode lug 152 is partially located in the foil exposure groove 114 and is electrically connected with the positive current collector 111. The protective glue 16 covers the part of the second positive electrode lug 152 located in the foil exposure groove 114 and does not cover the positive active layer 112. When applied in an electrical equipment, the first positive electrode lug 151 can be electrically connected with the positive electrode of the charging power supply 21 or the load 21 of the electrical equipment, and the negative electrode lug 153 can be electrically connected with the negative electrode of the charging power supply 21 or the load 21, so as to form a charging and discharging circuit. The first positive electrode lug 151 can be electrically connected with the positive electrode of the heating power supply 22 of the electrical equipment, and the second positive electrode lug 152 can be electrically connected with the negative electrode of the heating power supply 22 to form a heating circuit. According to the embodiment of the utility model, the first positive electrode lug 151 is located in the first empty foil area 113, and the second positive electrode lug 152 is located in the foil exposure groove 114, which can ensure that the first positive electrode lug 151 and the second positive electrode lug 152 are respectively electrically connected with the positive electrode and the negative electrode of the heating power supply to form a heating circuit with relatively large impedance, thereby providing a proper working temperature for the charging and discharging circuit formed by the electrical connection of the first positive electrode lug 151 and the negative electrode lug 153, thereby reducing the risk of lithium precipitation of the battery in a low-temperature large-rate charging state. In addition, the first positive electrode lug 151 is located at the starting end of the positive current collector 111, so that when the electrode body 10 is wound, the first positive electrode lug 151 will be located inside the electrode body 10 and will not form a protrusion on the outside of the electrode body 10, thereby helping to improve the energy density of the electrode body 10. In addition, the second positive electrode lug 152 is a heating electrode lug, and the current density is small, so when the protective glue 16 covers the second positive electrode lug 152, it can only cover the part located in the foil exposure groove 114 without covering the positive active layer 112, which makes the thickness of the protective glue 16 be absorbed by the foil exposure groove 114, so that after the winding of the electrode body 10 is completed, the thickness of the electrode body 10 will not be increased too much, which helps to improve the energy density.

[0032] The tab slot is usually formed by laser cleaning, that is, a positive active layer is coated on the positive current collector, and then a part of the positive active layer is removed by laser cleaning to obtain the tab slot. During the cleaning process, the positive active material at the edge of the tab slot is relatively loose. If the charge-discharge tab is placed in the tab slot, the current density near the tab slot will be larger during the charge-discharge process. In combination with the fact that the positive active material at the edge of the tab slot is relatively loose, the migration efficiency of lithium ions from the positive electrode sheet to the negative electrode sheet will be reduced during the charging process, so that part of the lithium ions are accumulated on the surface of the negative electrode sheet, resulting in lithium precipitation. In addition, when the tab is welded to the current collector, burrs on the welding point may pierce the separator, causing short circuit. Therefore, the protective glue needs to cover the welding area of the tab. Further, if the tab is a charge-discharge tab, the protective glue needs to exceed the boundary of the tab slot and cover a part of the positive active layer to avoid lithium precipitation on the surface of the negative electrode sheet. According to the embodiment of the present disclosure, the second positive tab 152 on the tab slot 114 is only used as a heating tab, the current density at the tab slot 114 is smaller, and the risk of lithium precipitation is smaller, so the protective glue 16 can be located completely in the tab slot 114.

[0033] When the tab is located at the middle position of the current collector, heat is easily accumulated in the interior of the electrode body, resulting in excessively high temperature near the tab. High temperature causes damage to the structure of the separator, resulting in that the original micropores or pores become smaller or even completely closed, so that ions cannot pass through the separator, thereby blocking the ion channel in the interior of the electrode body.

[0034] Reference Figure 4 and Figure 6 The second positive tab 152 can be made of a copper-based substrate 1521 and a nickel-based adhesion layer 1522 provided on at least part of the surface of the substrate 1521, and the second positive tab 152 is electrically connected to the positive current collector 111 through the adhesion layer 1522. By attaching the nickel-based adhesion layer 1522 to the copper-based substrate 1521, the second positive tab 152 has smaller impedance, and generates less heat when current passes through, so that the possibility of heat accumulation in the interior of the electrode body 10 can be reduced, thereby avoiding the closure of the pores of the separator 13 under high temperature.

[0035] During the charging process, the positive electrode potential will rise, and copper is prone to oxidation reaction to generate copper oxide, which will reduce the conductivity of the tab. In addition, copper may also release copper ions, which will reduce on the surface of the negative electrode sheet to form metal copper, so that part of the lithium ions are accumulated on the surface of the negative electrode sheet, resulting in lithium precipitation. Nickel has strong oxidation resistance and corrosion resistance, so attaching the nickel-based adhesion layer 1522 to the surface of the copper-based substrate 1521 can effectively prevent the oxidation or corrosion of the copper material and reduce the risk of lithium precipitation.

[0036] It can be understood that there are many ways to attach nickel to the surface of the copper substrate, for example, it can be achieved by thermal spraying, or it can be achieved by electrochemical deposition.

[0037] Exemplarily, the material of the second positive tab 152 can also be one or more of aluminum, iron plated with nickel, etc., and the embodiments of the present application do not make special limitations thereto, as long as the material can conduct electrons and form a heating circuit with the first positive tab 151 and the positive and negative poles of the heating power supply, respectively.

[0038] Reference Figure 4 and Figure 6 The second positive tab 152 includes a first segment 1523 and a second segment 1524 along the width direction of the positive plate 11, and an insulating glue 17 is provided on the outer periphery of the second positive tab 152 to separate the first segment 1523 and the second segment 1524, the second segment 1524 is at least partially located in the exposed foil groove 114, and the adhesion layer 1522 covers the surface of the second segment 1524 and stops at the insulating glue 17. The encapsulated electrode body 10 can be sealed by a heat sealing process, and the insulating glue 17 can be fixedly connected with the packaging body 20 when the packaging body 20 is heat sealed. In combination Figure 1 After encapsulation, the first segment 1523 is exposed outside the packaging body 20, and the second segment 1524 and the insulating glue 17 are located inside the packaging body 20. The adhesion layer 1522 covers the surface of the second segment 1524 and stops at the insulating glue 17, which can effectively prevent the substrate 1521 from being oxidized or corroded inside the packaging body 20, and ensure its safety performance.

[0039] It can be understood that the positive plate 11 and the negative plate 12 each have a winding head and a winding tail. In the winding process, the positive plate 11 and the negative plate 12 are wound from the winding head to the winding tail. That is, the winding direction of the electrode body 10 is the direction from the winding head to the winding tail of the positive plate 11 and the negative plate 12, that is Figure 3 the direction indicated by the arrow X. Referring to Figure 4 When the positive plate 11 is unfolded, the direction indicated by the arrow X is the length direction of the positive plate 11, and the direction indicated by the arrow Y is perpendicular to the length direction of the positive plate 11, which is the width direction of the positive plate 11.

[0040] As a possible implementation, referring to Figures 4 to 6, 0.8mm≤D1≤1.6mm, optionally, D1 can be 0.8mm, 1.0mm, 1.2mm, 1.4mm, etc.; 0.3≤H2 / H1≤0.9, optionally, H2 / H1 can be 0.3, 0.5, 0.7, 0.9, etc.; 15mm≤H1≤23mm, optionally, H1 can be 15mm, 18mm, 20mm, 23mm, etc.; 5mm≤H2≤10mm, optionally, H2 can be 5mm, 6mm, 8mm, etc. D1 is the average distance from the edge of the second positive tab 152 to the edge of the exposed tab slot 114, H1 is the size of the part of the first positive tab 151 overlapping the positive current collector 111 in the width direction of the positive plate 11, and H2 is the size of the part of the second positive tab 152 overlapping the positive current collector 111 in the width direction of the positive plate 11. Since the second positive tab 152 is a heating tab, the current density is small, so the size of the part of the second positive tab 152 overlapping the positive current collector 111 can be appropriately reduced compared to the first positive tab 151. According to the embodiment of the utility model, the size of the second positive tab 152 in the width direction of the positive plate 11 is smaller than that of the first positive tab 151, so the area of the exposed tab slot 114 can be adaptively reduced, which makes the cleaned positive active layer 112 less, which is beneficial to the energy density of the battery 100.

[0041] If the size of the second positive tab 152 is too small, the impedance will increase, and the heat generated when the current passes through will be large, which may cause the heat to accumulate in the inside of the electrode body 10, which is not conducive to the safety performance of the battery 100; if the size of the second positive tab 152 is too large, too much positive active layer 112 will be cleaned, which is not conducive to the energy density of the battery 100. According to the embodiment of the utility model, the average distance from the edge of the second positive tab 152 to the edge of the exposed tab slot 114 is limited, which can ensure the energy density of the battery 100 and the safety performance of the battery 100.

[0042] It can be understood that in the width direction of the positive plate 11, the exposed tab slot 114 has one edge, and in the length direction of the positive plate 11, the exposed tab slot 114 has two edges. D1 is the average distance from the edge of the protective glue 16 to the three edges of the exposed tab slot 114.

[0043] As a possible implementation, reference is made to Figure 3 , 3≤M≤N-3; 1 / 10≤W2 / W1≤1 / 2, the positive plate 11 includes N flat sections in the flat part 142, the second positive tab 152 is located on the Mth flat section from the starting end of the positive current collector among the N flat sections, W1 is the width of the flat part 142, and W2 is the distance from the second positive tab 152 to the closer one of the two curved parts 141.

[0044] During the winding process of the electrode body 10, there are positions where stress is relatively large. For example, the stress on the bending portion 141 in the positive electrode tab 11 is relatively large, and for another example, in the thickness direction of the electrode body 10, the stress on the flat section closer to the starting end of the positive current collector 111 is relatively large. During the charging and discharging process, the electrode body 10 will expand and contract in volume, and when the tab is located in a region where the stress is relatively large, micro-cracks are likely to form, and the corrosion environment in the electrode body 10 will accelerate the propagation of the cracks, and eventually may cause the tab to break. In addition, in the thickness direction of the electrode body 10, if the tab is located in the flat section away from the starting end of the positive current collector 111, i.e., the tab is close to the outer side, the part of the electrode body 10 after winding will have a significant bulge, and thus is likely to be damaged by external pressure or impact. According to the above implementation manner, the second positive tab 152 will be located between the 3rd flat section and the N-3rd flat section from the starting end of the positive current collector, and at the same time, the distance from the second positive tab 152 to the bending portion 141 is large. This implementation manner can both reduce the risk of stress corrosion of the second positive tab 152 and reduce the possibility of damage to the second positive tab 152 by external pressure.

[0045] As a possible implementation manner, with reference to Figure 4 , the distance between the first positive tab 151 and the second positive tab 152 along the length direction of the positive electrode tab 11 is D2, and the value range of the distance D2 can be: 200mm≤D2≤1900mm. The longer the part of the positive current collector 111 between the first positive tab 151 and the second positive tab 152, the greater the impedance of this part of the positive current collector 111, the more heat generated during electrification, and the better the heating effect. According to the positive electrode tab 11 set according to the above range, both the stability and safety of the second positive tab 152 can be ensured, and the heating effect can also be guaranteed.

[0046] With reference to Figure 3 and Figure 4 , in the case where the first positive tab 151 is located at the winding starting end of the positive electrode tab 11, the winding starting end of the negative current collector 121 can be provided with a second empty foil area 123, and the negative tab 153 is electrically connected to the negative current collector 121 at the second empty foil area 123. When the first positive tab 151 and the negative tab 153 are close to each other, the impedance of the charging and discharging circuit is low, which helps to reduce the heat generation of the battery. Further, the first positive tab 151 and the negative tab 153 are both located at the winding starting end, so during the winding process of the electrode tab, the position of the tab is not easily affected by the subsequent winding layers and position offset, which makes the position of the tab always consistent, reducing the problem of inaccurate position caused by winding error.

[0047] It can be understood that in some other embodiments, the winding ending end of the negative current collector 121 can be provided with a negative electrode tab empty foil area not covered by the negative active layer 122, and the negative tab 153 is connected to the negative electrode tab empty foil area.

[0048] In addition to the winding start end and the winding end of the negative current collector 121, the negative tab 153 can also be connected to the middle part of the negative current collector 121 in the winding direction. As an example, the negative active layer 122 can include a negative tab groove that exposes part of the surface of the negative current collector 121, and the negative tab 153 is connected to the part of the surface of the negative current collector 121 exposed by the negative tab groove.

[0049] As a possible implementation, the area of the second positive tab 152 can be less than or equal to the area of the first positive tab 151. The second positive tab 152 has a smaller area, that is, the exposed tab groove 114 has a smaller area, and the area of the cleaned positive active layer 112 is also smaller, which is beneficial to the energy density of the battery.

[0050] The positive current collector 111 can have a thickness T1, and the first positive tab 151 and the second positive tab 152 can have a thickness T2. The thickness T1 can be in the range of 7 μm≤T1≤20 μm, the thickness T2 can be in the range of 50 μm≤T2≤150 μm, and the thickness T1 and the thickness T2 can satisfy 6≤T2 / T1≤15. Selecting the values of the thickness T1 and the thickness T2 and the ratio T2 / T1 in the above ranges can make the welding of the positive tab and the positive current collector 111 more firm, avoid the problem that the positive current collector 111 is damaged when the positive tab is welded, causing the impedance to increase, and also avoid the positive tab from melting due to overload when high-rate charging and high-current heating.

[0051] The resistance value of the part of the positive current collector 111 between the first positive tab 151 and the second positive tab 152 is R1, the resistance value of the part of the positive current collector 111 welded with the first positive tab 151 is R2, and the resistance value of the part of the positive current collector 111 welded with the second positive tab 152 is R3. The resistance values R1, R2 and R3 can satisfy R1>R2, and / or R1>R3, and / or R2>R3.

[0052] The part of the positive current collector 111 welded with the second positive tab 152 can not constitute part of the charging and discharging circuit, but only part of the heating circuit. Setting the resistance value R3 of the part of the positive current collector 111 welded with the second positive tab 152 to be slightly smaller, that is, smaller than the resistance value R2 of the part of the positive current collector 111 welded with the first positive tab 151, can make the second positive tab 152 have a smaller impedance, and generate less heat when electrified. This can reduce the heat accumulation near the second positive tab 152, and avoid the problem that the diaphragm 13 will close at high temperatures.

[0053] In a preferred example, the resistance value R1 can be in the range of 28mΩ≤R1≤105mΩ, and / or, the resistance value R2 can be in the range of 10mΩ≤R2≤20mΩ, and / or, the resistance value R3 can be in the range of 5mΩ≤R3≤18mΩ.

[0054] Back to Figure 3 In the thickness direction of the electrode body 10, i.e. the direction indicated by the arrow V, the orthogonal projection of any two of the first positive tab 151, the second positive tab 152 and the negative tab 153 on a projection plane perpendicular to the thickness direction do not overlap with each other. Accordingly, the first positive tab 151, the second positive tab 152 and the negative tab 153 will not increase the thickness of the electrode body 10 too much, thereby helping to improve the energy density.

[0055] In some embodiments, the thickness of the negative current collector 121 is T3, and the thickness of the negative tab 153 is T4. The thickness T3 can be in the range of 3μm≤T3≤20μm, and the thickness T4 can be in the range of 50μm≤T4≤150μm. The thickness T3 and the thickness T4 can satisfy 7≤T4 / T3≤18. In this way, it can ensure that the welding of the negative tab 153 and the negative current collector 121 is more firm, while it can avoid the problem that the negative current collector 121 is damaged when welding the negative tab 153, resulting in increased impedance. Further, it can also avoid the problem that the thickness of the tab is not up to standard, resulting in the tab being overloaded and melted when charging at a high rate.

[0056] Referring to Figure 7 The utility device 200 can be, but is not limited to, an electronic device, an electric vehicle or a household appliance, etc. The utility device 200 includes the battery 100 described above, and can further include a charging power source or a load 21, a heating power source 22, a charging and discharging circuit and a heating circuit. The charging and discharging circuit is used to electrically connect the first positive tab 151 to the positive electrode of the charging power source or the load 21, and electrically connect the negative tab 153 to the negative electrode of the charging power source or the load 21. The heating circuit is used to electrically connect the first positive tab 151 to the positive electrode of the heating power source 22, and electrically connect the second positive tab 152 to the negative electrode of the heating power source 22.

[0057] Continuing to refer to Figure 7 The utility device 200 can further include a temperature sensor 23 and a controller 24. The temperature sensor 23 can be in communication connection with the controller 24, and can sense the temperature of the tab or the temperature of the electrode body 10, and transmit the sensing result to the controller 24. The controller 24 will execute a preset program according to the sensing result in response to receiving the sensing result, and turn on or turn off the heating circuit and the charging and discharging circuit.

[0058] As an example, in the case where the first positive tab 151 is used as the heating tab and the charge / discharge tab, the second positive tab 152 is used as the heating tab, and the negative tab 153 is used as the charge / discharge tab, the program executed by the controller 24 of the electric device 200 can include the following steps.

[0059] Step one: When the temperature sensor 23 monitors that the ambient temperature where the electrode body 10 is located is lower than the normal temperature environment, for example, 25℃, the controller 24 can control the heating power supply 22 to heat the electrode body 10, so that the temperature of the electrode body 10 gradually rises until it reaches the required preset temperature, for example, 25℃. At this time, the positive electrode of the heating power supply 22 is connected with the first positive tab 151, and the negative electrode of the heating power supply 22 is connected with the second positive tab 152, forming a heating circuit, and the positive tab 11 between the first positive tab 151 and the second positive tab 152 of the positive tab 11 acts as a heating resistor to heat the electrode body 10.

[0060] Step two: When the temperature sensor 23 monitors that the electrode body 10 is heated to the preset temperature, the controller 24 controls the charging power supply 21 to charge the battery. At this time, the positive electrode of the charging power supply 21 is connected with the first positive tab 151, and the negative electrode of the charging power supply 21 is connected with the negative tab 153, forming a charge / discharge circuit, and the battery is charged and discharged at the preset temperature, which can avoid the problem of lithium precipitation when the battery is charged at low temperature.

[0061] It should be noted that there is a contact resistance between the tab and the tab, which will cause additional heat at the contact part. When the current is too large, the heat accumulation of the contact resistance will also increase, increasing the risk of tab melting. Therefore, when heating the electrode body 10, the current should be avoided to be too large. As an example, the current of the heating power supply 22 can be limited to a range of 5A as the minimum current and 50A as the maximum current.

[0062] It can be understood that in other embodiments, the charging power supply 21 and the heating power supply 22 can work at the same time to realize heating and charging at the same time.

[0063] It should be understood that the term "comprising" and its variants used in the present application are open and inclusive, i.e. "including but not limited to". The term "according to" is "at least partially according to". The term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least another embodiment". The term "multiple" means "more than one", which means to cover the cases of two, three or more.

[0064] It should be understood that although the terms "first" or "second" and the like can be used in the present application to describe various elements, for example, the first positive tab and the second positive tab, these elements are not set by these terms, and these terms are only used to distinguish one element from another.

[0065] The utility model discloses the protection scope is not limited to the above -mentioned embodiment, any person skilled in the art in the utility model discloses the technical range, can think of change or replacement, all should cover in the utility model's protection scope. Therefore, the protection scope of the utility model should be the protection scope of claims.

Claims

1. A battery, characterized by, The battery includes a positive electrode sheet, a negative electrode sheet, and a separator, the positive electrode sheet and the negative electrode sheet are stacked and roll-wound with the separator therebetween to form an electrode body, the electrode body includes two curved portions and a flat portion between the two curved portions; The positive electrode sheet includes a positive current collector, a positive active layer, a first positive tab, a second positive tab, and a protective adhesive, a first empty foil area is provided at a starting end of the positive current collector, the positive active layer is provided with an exposed foil groove in the flat portion and exposing the positive current collector, the first positive tab is electrically connected to the positive current collector at the first empty foil area, the second positive tab is partially located in the exposed foil groove and electrically connected to the positive current collector, and the protective adhesive covers the part of the second positive tab located in the exposed foil groove and does not cover the positive active layer. The negative electrode sheet includes a negative current collector and a negative tab electrically connected to the negative current collector, the first positive tab and the negative tab are used to form a charging and discharging circuit, and the first positive tab and the second positive tab are used to form a heating circuit.

2. The battery of claim 1, wherein, The second positive tab includes a copper base and a nickel adhesion layer provided on at least part of the surface of the base, and the second positive tab is electrically connected to the positive current collector through the adhesion layer.

3. The battery of claim 2, wherein, The second positive tab includes a first segment and a second segment along the width direction of the positive electrode sheet, an insulating adhesive is provided on the outer periphery of the second positive tab to separate the first segment and the second segment, the second segment is at least partially located in the exposed foil groove, and the adhesion layer covers the surface of the second segment and stops at the insulating adhesive.

4. The battery of any one of claims 1 to 3, wherein: 0.8 mm≤D1≤1.6 mm; and / or 0.3≤H2 / H1≤0.9; and / or 15 mm≤H1≤23 mm; and / or 5 mm≤H2≤10 mm, wherein D1 is an average distance from an edge of the second positive tab to an edge of the exposed foil groove, H1 is a size of a part of the first positive tab overlapping the positive current collector in the width direction of the positive electrode sheet, and H2 is a size of a part of the second positive tab overlapping the positive current collector in the width direction of the positive electrode sheet.

5. The battery of any one of claims 1 to 3, wherein: 3≤M≤N-3; and / or 1 / 10≤W2 / W1≤1 / 2; and / or 200 mm≤D2≤1900 mm, wherein the positive electrode sheet includes N flat segments in the flat portion, the second positive tab is located on an Mth flat segment from a starting end of the positive current collector among the N flat segments, W1 is a width of the flat portion, W2 is a distance from the second positive tab to a closer one of the two curved portions, and D2 is a distance between the first positive tab and the second positive tab in a length direction of the positive electrode sheet.

6. The battery of any one of claims 1 to 3, wherein, The negative electrode sheet further includes a negative active layer disposed on the negative current collector, a second empty foil area is provided at a starting end of the negative current collector, and the negative tab is electrically connected to the negative current collector at the second empty foil area.

7. The battery of any one of claims 1 to 3, wherein, An area of the second positive tab is less than or equal to an area of the first positive tab. 8.The battery according to any one of claims 1 to 3, wherein: 7 μm≤T1≤20 μm; 50 μm≤T2≤150 μm; 6≤T2 / T1≤15, 3 μm≤T3≤20 μm; 50 μm≤T4≤150 μm; and 7≤T4 / T3≤18, wherein the first and second positive tabs are welded to the positive current collector, T1 is a thickness of the positive current collector, T2 is a thickness of either of the first and second positive tabs, the negative tab is welded to the negative current collector, T3 is a thickness of the negative current collector, and T4 is a thickness of the negative tab. 9.The battery according to any one of claims 1 to 3, wherein: R1>R2; and / or, R1>R3; and / or, R2>R3, wherein R1 is a resistance value of a portion of the positive current collector between the first and second positive tabs, R2 is a resistance value of a portion of the positive current collector welded to the first positive tab, and R3 is a resistance value of a portion of the positive current collector welded to the second positive tab. including: the battery according to any one of claims 1 to 9; a charging power source or a load; a heating power source; a charge-discharge circuit configured to electrically connect the first positive tab to a positive electrode of the charging power source or the load and electrically connect the negative tab to a negative electrode of the charging power source or the load; a heating circuit configured to electrically connect the first positive tab to a positive electrode of the heating power source and electrically connect the second positive tab to a negative electrode of the heating power source; a temperature sensor configured to sense a temperature of the electrode body; and a controller communicatively connected to the temperature sensor and configured to receive a sensing result of the temperature sensor and to turn on or off the heating circuit and the charge-discharge circuit based on the sensing result. ​ ​ ​ ​ 10. An electric device, characterized by ​ ​ ​ ​ ​ ​ ​ ​ ​

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