Battery cell and electric equipment

Abstract

The invention provides a battery cell and electric equipment, the battery cell comprises an electrode assembly and a bonding piece, and the electrode assembly is formed by winding a positive pole piece, a diaphragm and a negative pole piece which are stacked. The innermost ring of the positive pole piece comprises a first straight section, a first corner section and a second straight section, the innermost ring of the negative pole piece comprises a third straight section, a second corner section and a fourth straight section, and one end, far away from the first corner section, of the first straight section is a first winding starting end. The end, away from the second corner section, of the third straight section is a second winding starting end. The positive pole piece is provided with a first groove opposite to the second winding starting end at the first corner section; the first groove comprises a first sub-groove and a second sub-groove penetrating through the first sub-groove to the first current collector, and the first area of the first current collector is exposed out of the second sub-groove. The bonding piece is arranged in the second sub-groove and at least partially covers the first sub-groove. The possibility of metal ion precipitation can be reduced, and the safety of the battery cell is improved.

Description

Technical Field

[0001] The present application relates to the technical field of batteries, and more particularly, to an electric core and an electrical device using the same. Background Art

[0002] With the rapid development of electronic information technology, various electronic devices are also developing towards the direction of intelligence and multi-functionality, and the safety requirements for batteries are getting higher and higher. Therefore, how to improve the safety of batteries has become an urgent problem to be solved in the battery field. Summary of the Invention

[0003] The present application provides an electric core and an electrical device using the same, which can improve the safety of the electric core.

[0004] In a first aspect, the present application provides an electric core, which includes an electrode assembly formed by winding a positive electrode tab, a separator, and a negative electrode tab stacked. The innermost circle of the positive electrode tab includes a first straight section, a first corner section, and a second straight section. The first corner section connects the first straight section and the second straight section. One end of the first straight section away from the first corner section is the first winding starting end of the positive electrode tab. The innermost circle of the negative electrode tab includes a third straight section, a second corner section, and a fourth straight section. The second corner section connects the third straight section and the fourth straight section. One end of the third straight section away from the second corner section is the second winding starting end of the negative electrode tab. The positive electrode tab includes a first current collector and a first material layer provided on the surface of the first current collector. The positive electrode tab has a first groove at the first corner section. The first current collector has a first region. Along the width direction of the electrode assembly, the first groove is opposite to the second winding starting end. The first groove includes a first sub-groove and a second sub-groove penetrating the first sub-groove to the first current collector. The first region is exposed in the second sub-groove. An adhesive is disposed in the second sub-groove and at least partially covers the first sub-groove.

[0005] In the above technical solution, in the first corner section, after the metal ions in the first material layer on the side of the first current collector facing the winding center of the electrode assembly are deintercalated, there is not enough material layer at the second winding starting end for the metal ions to be intercalated. By providing an adhesive in the first groove, the possibility of metal ion precipitation in the first corner section can be reduced. And since the adhesive is provided in the first groove, the adhesive will not protrude from the positive electrode plate or the thickness of the protruding part is small, so that the overall thickness of the adhesive and the positive electrode plate can be reduced, the overall volume of the electrode assembly can be reduced, and the energy density of the battery cell can be increased. In the first corner section, bending of the positive electrode plate may cause cracks in the first current collector. The metal ions in the first material layer provided on the side of the first current collector facing the winding center of the electrode assembly enter the side of the first current collector facing away from the winding center of the electrode assembly through the cracks, resulting in the problem of metal ion precipitation. By exposing at least a part of the first current collector in the first groove, the metal ions in the first material layer can be prevented from entering the side of the first current collector facing away from the winding center of the electrode assembly through the cracks in the first current collector, thereby reducing the possibility of metal ion precipitation and improving the safety of the battery cell. The adhesive can also play an insulating role between the first corner section and the second winding starting end, reducing the possibility of short circuit due to contact between the positive electrode plate and the negative electrode plate, and further improving the safety of the battery cell. The metal ions include sodium ions, lithium ions or magnesium ions.

[0006] In the above technical solution, by exposing the first current collector in the second sub-groove and providing the adhesive in the second sub-groove and at least partially covering the first sub-groove, not only can the covering effect of the adhesive on the first groove be better, reducing the risk of exposure of the first current collector and improving the safety of the battery cell, but also the adhesive will not protrude from the positive electrode plate or the thickness of the protruding part is small, so that the overall thickness of the adhesive and the positive electrode plate can be reduced, the overall volume of the electrode assembly can be reduced, and the energy density of the battery cell can be increased.

[0007] In some embodiments of the present application, along the width direction of the electrode assembly, the first starting end and the second starting end are respectively located on both sides of the center of the battery cell, the first winding starting end is opposite to the second corner section, and the second winding starting end is opposite to the first corner section.

[0008] In the above technical solution, by making the first starting end and the second starting end respectively located on both sides of the center of the battery cell along the width direction of the electrode assembly, and the first winding starting end is opposite to the second corner section, and the second winding starting end is opposite to the first corner section, a butt-insert structure is formed between the first winding starting end and the second winding starting end, which is convenient for the winding and forming of the electrode assembly, efficiently utilizes the internal space of the battery cell, and increases the energy density of the battery cell.

[0009] In some embodiments of the present application, along the winding direction of the electrode assembly, the width of the first region is W, satisfying 1 mm ≤ W ≤ 25 mm.

[0010] In the above technical solution, since the first region of the first current collector is opposite to the second winding starting end along the width direction of the electrode assembly, when the electrode assembly is wound and formed, the bending angle of the first region is relatively large and cracks are more likely to occur. By exposing the first region of the first current collector in the first groove, it is possible to further reduce the metal ions in the first material layer from passing through the cracks of the first current collector from the side of the first current collector facing the winding center of the electrode assembly to the side of the first current collector facing away from the winding center of the electrode assembly, thereby further reducing the possibility of metal ion precipitation and improving the safety of the battery cell. When W is greater than or equal to 1 mm, it is possible to further reduce the metal ions in the first material layer from passing through the cracks of the first current collector from the side of the first current collector facing the winding center of the electrode assembly to the side of the first current collector facing away from the winding center of the electrode assembly, thereby further reducing the possibility of metal ion precipitation and improving the safety of the battery cell; when W is less than or equal to 25 mm, it is possible to make the volume of the first material layer relatively large, which is beneficial to improving the energy density of the battery cell; therefore, when 1 mm ≤ W ≤ 25 mm, it is possible to both further reduce the metal ions in the first material layer from passing through the cracks of the first current collector from the side of the first current collector facing the winding center of the electrode assembly to the side of the first current collector facing away from the winding center of the electrode assembly, thereby further reducing the possibility of metal ion precipitation and improving the safety of the battery cell, and make the volume of the first material layer relatively large, which is beneficial to improving the energy density of the battery cell.

[0011] In some embodiments of the present application, along the winding direction of the electrode assembly, at least one end of the adhesive is disposed on the first material layer.

[0012] In the above technical solution, by making at least one end of the adhesive disposed on the first material layer along the winding direction of the electrode assembly, the covering effect of the adhesive on the first groove can be better, the risk of exposure of the first current collector can be reduced, and further the risk of contact short circuit between the positive electrode sheet and the negative electrode sheet can be reduced, which is beneficial to improving the safety of the battery cell.

[0013] In some embodiments of the present application, along the winding direction of the electrode assembly, the first sub-groove has a first side wall and a second side wall. The distance between the first end of the adhesive and the first side wall is D1, satisfying D1 ≥ 0; the distance between the second end of the adhesive and the second side wall is D2, satisfying D2 ≥ 0.

[0014] In the above technical solution, by making the distance between the first end of the bonding member and the first side wall be D1, where D1≥0; and the distance between the second end of the bonding member and the second side wall be D2, where D2≥0, the bonding member is completely accommodated in the first groove, which can further make the part of the bonding member that does not protrude from the positive electrode tab or protrudes from the positive electrode tab have a smaller thickness, thereby further reducing the overall thickness of the bonding member and the positive electrode tab, further reducing the overall volume of the electrode assembly, and further increasing the energy density of the battery cell.

[0015] In some embodiments of the present application, the thickness of the first material layer located in the first sub-groove is H1, the thickness of the bonding member is H2, and the maximum thickness of the first material layer is H3, satisfying H1 + H2 ≤ H3.

[0016] In the above technical solution, by making the thickness H1 of the first material layer located in the first sub-groove, the thickness H2 of the bonding member, and the maximum thickness H3 of the first material layer satisfy H1 + H2 ≤ H3, the bonding member does not protrude from the positive electrode tab, thereby further reducing the overall thickness of the bonding member and the positive electrode tab, further reducing the overall volume of the electrode assembly, and further increasing the energy density of the battery cell.

[0017] In some embodiments of the present application, along the width direction of the electrode assembly, the bonding member and the third straight section have an overlapping area, and the length of the overlapping area is L1, satisfying L1≥0.5 mm.

[0018] In the above technical solution, by making the length L1 of the overlapping area between the bonding member and the third straight section along the width direction of the electrode assembly satisfy L1≥0.5 mm, the area of the first material layer covered by the bonding member can be made larger, further reducing the possibility of metal ion precipitation at the first corner section, which is beneficial to improving the safety of the battery cell and extending the service life of the battery cell.

[0019] In some embodiments of the present application, the negative electrode tab includes a second current collector and two layers of second material layers, and the two surfaces of the second current collector are completely covered with the two layers of second material layers.

[0020] In the above technical solution, by making the two surfaces of the second current collector be completely covered with the two layers of second material layers, the volume of the second material layer can be made larger, which is more conducive to the insertion and extraction of metal ions, thereby increasing the energy density of the battery cell.

[0021] In some embodiments of the present application, the electrode assembly includes two layers of separators, and the two layers of separators are respectively arranged on both sides of the negative electrode tab along its thickness direction. Along the opposite direction of the winding direction of the electrode assembly, the two layers of separators extend beyond the winding starting end of the negative electrode tab and are connected.

[0022] In the above technical solution, by making the electrode assembly include two separator films, the two separator films are respectively disposed on both sides of the negative electrode tab along its thickness direction, and in the opposite direction of the winding direction of the electrode assembly, the two separator films extend beyond the winding starting end of the negative electrode tab and are connected, so that the separator film can play an isolation role between the positive electrode tab and the negative electrode tab, reducing the risk of contact short circuit between the positive electrode tab and the negative electrode tab, and improving the safety of the battery cell.

[0023] In a second aspect, the present application provides an electrical device, including the battery cell as described above, and the battery cell is used to provide electrical energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings required for the embodiments. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can also be obtained based on these drawings.

[0025] Figure 1 A cross-sectional structural schematic diagram of a battery cell provided by some embodiments of the present application;

[0026] Figure 2 For Figure 1 A partial enlarged structural schematic diagram of part A of the battery cell in

[0027] Figure 3 A partial enlarged schematic diagram of a part of the structure of a battery cell provided by some embodiments of the present application;

[0028] Figure 4 A structural schematic diagram of the positive electrode tab of a battery cell provided by some embodiments of the present application after being unfolded;

[0029] Figure 5 A structural schematic diagram of the negative electrode tab of a battery cell provided by some embodiments of the present application after being unfolded;

[0030] Figure 6 A structural schematic diagram of the positive electrode tab of a battery cell provided by some other embodiments of the present application after being unfolded;

[0031] Figure 7 A structural schematic diagram of the separator film of a battery cell provided by some embodiments of the present application.

[0032] Icons: 10 - electrode assembly; 100 - positive electrode tab; 101 - first straight section; 102 - first corner section; 103 - second straight section; 110 - first current collector; 111 - first region; 120 - first material layer; 130 - first groove; 131 - first sub - groove; 1311 - first side wall; 1312 - second side wall; 132 - second sub - groove; 200 - separator; 300 - negative electrode tab; 301 - third straight section; 302 - second corner section; 303 - fourth straight section; 310 - second current collector; 320 - second material layer; 400 - bonding member; 510 - first tab; 520 - second tab; X - width direction of the electrode assembly; Y - thickness direction of the electrode assembly. Detailed implementation manners

[0033] To make the objectives, technical solutions and advantages of this application clearer, the technical solutions in the embodiments of this application will be clearly described below with reference to the accompanying drawings in the embodiments of this application. Obviously, the described embodiments are some, but not all, of the embodiments of this application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in this application fall within the scope of protection of this application.

[0034] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by those of ordinary skill in the technical field to which this application belongs; the terms used in the description of this application are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the description and claims of this application and the above - mentioned drawings are intended to cover non - exclusive inclusion.

[0035] The terms "first", "second", etc. in the description and claims of this application or the above - mentioned drawings are used to distinguish different objects and are not used to describe a specific order or primary - secondary relationship.

[0036] Referring to "embodiments" in this application means that specific features, structures or characteristics described in connection with the embodiments can be included in at least one embodiment of this application. The phrase appearing in various positions in the description does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments.

[0037] In the embodiments of this application, the same reference numerals represent the same components, and for the sake of brevity, in different embodiments, the detailed description of the same components is omitted. It should be understood that the thickness, length, width and other dimensions of various components shown in the drawings of the embodiments of this application, as well as the overall thickness, length, width and other dimensions of the integrated device, are only for illustrative purposes and should not constitute any limitation to this application.

[0038] With the development of the new energy industry, batteries are gradually evolving towards higher energy density and higher power density. The wound electrode assembly is formed by winding a positive electrode sheet, a separator, and a negative electrode sheet, and is pressed after winding, so that the cross-section of the electrode assembly in the direction perpendicular to the winding axis forms a runway shape, making the positive electrode sheet and the negative electrode sheet form a straight section and a corner section, and the first corner section of the innermost circle of the positive electrode sheet is opposite to the second winding starting end of the negative electrode sheet, and the second corner section of the innermost circle of the negative electrode sheet is opposite to the first winding starting end of the positive electrode sheet. Since there is not enough active material for the insertion of metal ions at the second winding starting end after the metal ions are deintercalated from the first corner section, an adhesive is provided at the first corner section to reduce the possibility of metal ion precipitation at the first corner section. However, due to the large bending angle of the first corner section, the first current collector of the positive electrode sheet located at the first corner section may crack, resulting in the problem that although the adhesive can prevent the metal ions in the first material layer on the side of the first corner section facing the winding center of the electrode assembly from precipitating, there is still a problem that the first material layer enters the side of the first current collector facing away from the winding center of the electrode assembly through the crack of the first current collector from the side of the first current collector facing the winding center of the electrode assembly, resulting in the precipitation of metal ions in the first material layer on the side of the first current collector facing away from the winding center of the electrode assembly, affecting the safety and service life of the battery cell. And the adhesive will increase the thickness of the electrode assembly, affecting the energy density of the battery cell.

[0039] To improve the safety of the battery cell, the present application provides a battery cell, which includes an electrode assembly formed by winding a positive electrode tab, a separator, and a negative electrode tab stacked on top of each other. The innermost circle of the positive electrode tab includes a first straight section, a first corner section, and a second straight section. The first corner section connects the first straight section and the second straight section. One end of the first straight section away from the first corner section is the first winding start end of the positive electrode tab. The innermost circle of the negative electrode tab includes a third straight section, a second corner section, and a fourth straight section. The second corner section connects the third straight section and the fourth straight section. One end of the third straight section away from the second corner section is the second winding start end of the negative electrode tab. The positive electrode tab includes a first current collector and a first material layer provided on the surface of the first current collector. The positive electrode tab has a first groove at the first corner section. The first current collector has a first region. Along the width direction of the electrode assembly, the first groove is opposite to the second winding start end. The first groove includes a first sub-groove and a second sub-groove penetrating through the first sub-groove to the first current collector. The first region is exposed in the second sub-groove. An adhesive is provided in the second sub-groove and at least partially covers the first sub-groove. In the battery cell with such a structure, by providing the adhesive in the first groove, the possibility of metal ion precipitation at the first corner section can be reduced, and at least part of the adhesive is accommodated in the first groove, which can make the adhesive not protrude from the positive electrode tab or the thickness of the protruding part of the positive electrode tab is small, so that the overall thickness of the adhesive and the positive electrode tab can be reduced, the overall volume of the electrode assembly can be reduced, and the energy density of the battery cell can be improved. Since at the first corner section, bending of the positive electrode tab may cause cracks in the first current collector, metal ions of the first material layer provided on the side of the first current collector facing the winding center of the electrode assembly enter the side of the first current collector facing away from the winding center of the electrode assembly through the cracks, resulting in the problem of metal ion precipitation. By exposing at least part of the first current collector in the first groove, the metal ions of the first material layer can be reduced from entering the side of the first current collector facing away from the winding center of the electrode assembly through the cracks of the first current collector on the side of the first current collector facing the winding center of the electrode assembly, thereby reducing the possibility of metal ion precipitation and improving the safety of the battery cell. The adhesive can also play an insulating role between the first corner section and the second winding start end, reducing the possibility of contact short circuit between the positive electrode tab and the negative electrode tab, and further improving the safety of the battery cell. By exposing the first current collector in the second sub-groove, providing the adhesive in the second sub-groove and at least partially covering the first sub-groove, it can not only make the coverage effect of the adhesive on the first groove better, reduce the risk of exposure of the first current collector, improve the safety of the battery cell, but also make the adhesive not protrude from the positive electrode tab or the thickness of the protruding part of the positive electrode tab is small, so that the overall thickness of the adhesive and the positive electrode tab can be reduced, the overall volume of the electrode assembly can be reduced, and the energy density of the battery cell can be improved.

[0040] The battery cell provided in the embodiments of the present application can be a secondary battery or a primary battery. For example, it can be a lithium-ion battery, a sodium-ion battery, a magnesium-ion battery, etc. The embodiments of the present application are not limited thereto. The battery cell can be in a cylindrical shape, a flat shape, a cuboid shape or other shapes, and the embodiments of the present application are not limited thereto either.

[0041] The embodiments of the present application provide an electrical device using a battery cell as a power source. The electrical device can be, but is not limited to, a mobile phone, a tablet computer, a laptop computer, an electric toy, an electric tool, a battery car, an electric vehicle, a ship, a spacecraft, etc.

[0042] See Figures 1 to 3 , Figure 1 is a schematic cross-sectional structure diagram of a battery cell provided in some embodiments of the present application; Figure 2 is Figure 1 a partial enlarged structure diagram of the A position of the battery cell in Figure 3 is a partial enlarged schematic diagram of a part of the structure of a battery cell provided in some embodiments of the present application.

[0043] Some embodiments of the present application provide a battery cell, which includes an electrode assembly 10. The electrode assembly 10 is formed by winding a positive electrode tab 100, a separator 200, and a negative electrode tab 300 arranged in a stacked manner. The innermost circle of the positive electrode tab 100 includes a first straight section 101, a first corner section 102, and a second straight section 103. The first corner section 102 connects the first straight section 101 and the second straight section 103. One end of the first straight section 101 away from the first corner section 102 is the first winding start end of the positive electrode tab 100. The innermost circle of the negative electrode tab 300 includes a third straight section 301, a second corner section 302, and a fourth straight section 303. The second corner section 302 connects the third straight section 301 and the fourth straight section 303. One end of the third straight section 301 away from the second corner section 302 is the second winding start end of the negative electrode tab 300.

[0044] In some embodiments, the positive electrode tab 100 includes a first current collector 110 and a first material layer 120 provided on the surface of the first current collector 110. The positive electrode tab 100 has a first groove 130 at the first corner section 102. At least a part of the first current collector 110 is exposed in the first groove 130. Along the width direction X of the electrode assembly, the first groove 130 is opposite to the second winding start end. The battery cell further includes an adhesive 400, and the adhesive 400 is provided in the first groove 130.

[0045] Since the positive electrode tab 100 contains positive electrode metal, metal ions are first deintercalated from the positive electrode tab 100 and then move in the battery cell through the electrolyte. By providing the adhesive 400 at the first corner section 102 of the positive electrode tab 100, the possibility of metal ion precipitation at the first corner section 102 can be reduced, the safety of the battery cell can be improved, and the service life of the battery cell can be extended.

[0046] Since after the deintercalation of metal ions from the first material layer 120 on the side of the first current collector 110 facing the winding center of the electrode assembly 10 in the first corner section 102, there is not enough material layer for the metal ions to intercalate at the second winding starting end, by providing the bonding member 400 in the first groove 130, it is possible to block the deintercalation of metal ions from the first material layer 120 on the side of the first current collector 110 facing the winding center of the electrode assembly 10, thereby reducing the possibility of metal ion precipitation in the first corner section 102. And the bonding member 400 is provided in the first groove 130, which can make the part of the bonding member 400 that does not protrude from the positive electrode tab 100 or protrudes from the positive electrode tab 100 have a small thickness, so as to reduce the overall thickness of the bonding member 400 and the positive electrode tab 100, reduce the overall volume of the electrode assembly 10, and improve the energy density of the battery cell. Since in the first corner section 102, the bending of the positive electrode tab 100 may cause cracks in the first current collector 110, and the first material layer 120 provided on the side of the first current collector 110 facing the winding center of the electrode assembly 10 enters the side of the first current collector 110 facing away from the winding center of the electrode assembly 10 through the crack, resulting in the problem of metal ion precipitation. By making at least part of the first current collector 110 exposed in the first groove 130, it is possible to reduce the entry of the first material layer 120 from the side of the first current collector 110 facing the winding center of the electrode assembly 10 into the side of the first current collector 110 facing away from the winding center of the electrode assembly 10 through the crack of the first current collector 110, thereby reducing the possibility of metal ion precipitation and improving the safety of the battery cell. The bonding member 400 can also play an insulating role between the first corner section 102 and the second winding starting end, reducing the possibility of short circuit due to contact between the positive electrode tab 100 and the negative electrode tab 300, and further improving the safety of the battery cell.

[0047] In some embodiments, along the width direction X of the electrode assembly, the first starting end and the second starting end are respectively located on both sides of the center of the battery cell, the first winding starting end is opposite to the second corner section 302, and the second winding starting end is opposite to the first corner section 102.

[0048] By making the first starting end and the second starting end respectively located on both sides of the center of the battery cell along the width direction X of the electrode assembly, and the first winding starting end is opposite to the second corner section 302, and the second winding starting end is opposite to the first corner section 102, a plug-in structure is formed between the first winding starting end and the second winding starting end, which is convenient for the winding and forming of the electrode assembly 100.

[0049] In some embodiments, in the first straight section 101 and the second straight section 103, first material layers 120 are disposed on both sides of the first current collector 110 in its thickness direction. The negative electrode tab 300 includes a second current collector 310 and a second material layer 320 disposed on the surface of the second current collector 310. In the third straight section 301 and the fourth straight section 303, second material layers 320 are disposed on both sides of the second current collector 310 in its thickness direction.

[0050] By disposing first material layers 120 on both sides of the first current collector 110 in its thickness direction in the first straight section 101 and the second straight section 103, and disposing second material layers 320 on both sides of the second current collector 310 in its thickness direction in the third straight section 301 and the fourth straight section 303, the material layers in the first straight section 101, the second straight section 103, the third straight section 301, and the fourth straight section 303 can all be used for the insertion and extraction of metal ions, making the volume ratio of the material layers in the electrode assembly 10 larger and the utilization rate of the material layers higher, which is beneficial to improving the energy density of the battery cell.

[0051] See Figure 2 and Figure 3 , in some embodiments, the first current collector 110 has a first region 111. The first groove 130 includes a first sub-groove 131 and a second sub-groove 132 that penetrates the first sub-groove 131 to the first current collector 110. The first region 111 is exposed in the second sub-groove 132. The bonding member 400 is disposed in the second sub-groove 132 and at least partially covers the first sub-groove 131.

[0052] By exposing the first current collector 110 in the second sub-groove 132, disposing the bonding member 400 in the second sub-groove 132, and at least partially covering the first sub-groove 131, not only can the covering effect of the bonding member 400 on the first groove 130 be better, reducing the risk of exposure of the first current collector 110 and improving the safety of the battery cell, but also the bonding member 400 does not protrude from the positive electrode tab 100 or the thickness of the protruding part of the positive electrode tab 100 is small, so that the overall thickness of the bonding member 400 and the positive electrode tab 100 can be reduced, the overall volume of the electrode assembly 10 can be reduced, and the energy density of the battery cell can be improved.

[0053] See also Figure 4 , Figure 4 is a schematic structural diagram of the unfolded positive electrode tab of the battery cell provided by some embodiments of the present application.

[0054] In some embodiments, along the width direction X of the electrode assembly, the first region 111 is opposite to the second winding starting end. Along the winding direction of the electrode assembly, the width of the first region 111 is W, satisfying 1 mm ≤ W ≤ 25 mm. For example, W can be 1 mm, 6 mm, 10 mm, 20 mm, 25 mm, etc. That is, along Figure 4 the length direction B after the positive electrode tab is unfolded, the width of the first region 111 is W.

[0055] The width direction X, the thickness direction Y, and the winding axis direction of the electrode assembly are perpendicular to each other in pairs.

[0056] Since, along the width direction X of the electrode assembly, the first region 111 of the first current collector 110 is opposite to the second winding starting end, when the electrode assembly 10 is wound and formed, the bending angle of the first region 111 is relatively large and cracks are more likely to occur. By exposing the first region 111 of the first current collector 110 in the first groove 130, it is possible to further reduce the metal ions of the first material layer 120 from passing through the cracks of the first current collector 110 from the side of the first current collector 110 facing the winding center of the electrode assembly 10 to the side of the first current collector 110 facing away from the winding center of the electrode assembly 10, thereby further reducing the possibility of metal ion precipitation and improving the safety of the battery cell. When W is greater than or equal to 1 mm, it is possible to further reduce the metal ions of the first material layer 120 from passing through the cracks of the first current collector 110 from the side of the first current collector 110 facing the winding center of the electrode assembly 10 to the side of the first current collector 110 facing away from the winding center of the electrode assembly 10, thereby further reducing the possibility of metal ion precipitation and improving the safety of the battery cell; when W is less than or equal to 25 mm, it is possible to make the volume of the first material layer 120 relatively large, which is beneficial to improving the energy density of the battery cell; therefore, when 1 mm ≤ W ≤ 25 mm, it is possible to both further reduce the metal ions of the first material layer 120 from passing through the cracks of the first current collector 110 from the side of the first current collector 110 facing the winding center of the electrode assembly 10 to the side of the first current collector 110 facing away from the winding center of the electrode assembly 10, thereby further reducing the possibility of metal ion precipitation and improving the safety of the battery cell, and making the volume of the first material layer 120 relatively large, which is beneficial to improving the energy density of the battery cell.

[0057] Referring to Figure 2 , in some embodiments, along the winding direction of the electrode assembly, at least one end of the bonding member 400 is disposed on the first material layer 120.

[0058] By arranging at least one end of the bonding member 400 on the first material layer 120 along the winding direction of the electrode assembly, the covering effect of the bonding member 400 on the first groove 130 can be better, the risk of exposure of the first current collector 110 can be reduced, and further the risk of contact short circuit between the positive electrode tab 100 and the negative electrode tab 300 can be reduced, which is beneficial to improving the safety of the battery cell.

[0059] In some embodiments, both ends of the bonding member 400 are arranged on the first material layer 120 along the winding direction of the electrode assembly. This can further improve the covering effect of the bonding member 400 on the first groove 130, reduce the risk of exposure of the first current collector 110, and further reduce the risk of contact short circuit between the positive electrode tab 100 and the negative electrode tab 300, which is beneficial to improving the safety of the battery cell.

[0060] In some embodiments, along the winding direction of the electrode assembly, the first sub-groove 131 has a first side wall 1311 and a second side wall 1312. The distance between the first end of the bonding member 400 and the first side wall 1311 is D1, where D1≥0. For example, D1 can be 0mm, 0.1mm, 0.15mm, 0.2mm, or 0.3mm, etc. The distance between the second end of the bonding member 400 and the second side wall 1312 is D2, where D2≥0. For example, D2 can be 0mm, 0.1mm, 0.15mm, 0.2mm, or 0.3mm, etc.

[0061] By setting the distance between the first end of the bonding member 400 and the first side wall 1311 as D1, where D1≥0, and the distance between the second end of the bonding member 400 and the second side wall 1312 as D2, where D2≥0, the bonding member 400 can be completely accommodated in the first groove 130, which can further ensure that the bonding member 400 does not protrude from the positive electrode tab 100 or the thickness of the protruding part of the bonding member 400 from the positive electrode tab 100 is small, thereby further reducing the overall thickness of the bonding member 400 and the positive electrode tab 100, further reducing the overall volume of the electrode assembly 10, and further improving the energy density of the battery cell.

[0062] See Figure 4 , in some embodiments, the thickness of the first material layer 120 located in the first sub-groove 131 is H1, the thickness of the bonding member 400 is H2, and the maximum thickness of the first material layer 120 is H3, where H1 + H2≤H3. For example, H1 + H2 can be H3, 0.95*H3, 0.92*H3, 0.9*H3, or 0.8*H3, etc.

[0063] By making the thickness H1 of the first material layer 120 located in the first sub-groove 131, the thickness H2 of the bonding member 400, and the maximum thickness H3 of the first material layer 120 satisfy H1 + H2 ≤ H3, the bonding member 400 does not protrude from the positive electrode tab 100, thereby further reducing the overall thickness of the bonding member 400 and the positive electrode tab 100, further reducing the overall volume of the electrode assembly 10, and further improving the energy density of the battery cell.

[0064] See Figure 2 , in some embodiments, along the width direction X of the electrode assembly, the bonding member 400 and the third straight section 301 have an overlapping area, and the length of the overlapping area is L1, satisfying L1 ≥ 0.5 mm. For example, L1 can be 0.5 mm, 0.7 mm, 0.9 mm, 1 mm, 2 mm, etc.

[0065] By making the length L1 of the overlapping area between the bonding member 400 and the third straight section 301 along the width direction X of the electrode assembly satisfy L1 ≥ 0.5 mm, the area of the first material layer 120 covered by the bonding member 400 can be made larger, further reducing the possibility of metal ion precipitation at the first corner section 102, which is beneficial to improving the safety of the battery cell and extending the service life of the battery cell.

[0066] In some embodiments, along the width direction X of the electrode assembly, the distance between the second winding start end of the negative electrode tab 300 and the first current collector 110 of the first corner section 102 is greater than 0. For example, the distance between the second winding start end of the negative electrode tab 300 and the first current collector 110 of the first corner section 102 is 0.1 mm, 0.15 mm, 0.2 mm, or 0.3 mm, etc. This can facilitate the arrangement of the bonding member 400 in the first groove 130 and reduce the possibility of short circuit between the positive electrode tab 100 and the negative electrode tab 300, improving the safety of the battery cell.

[0067] In some embodiments, the bonding member 400 may include at least one of materials such as epoxy resin, polypropylene, polyolefin, rubber, etc.

[0068] See Figure 5 , Figure 5 is a schematic structural diagram of the unfolded negative electrode tab of the battery cell provided in some embodiments of the present application.

[0069] In some embodiments, the negative electrode tab 300 includes a second current collector 310 and two layers of second material layers 320, and the two surfaces of the second current collector 310 are completely covered with the two layers of second material layers 320. The second material layer is a negative electrode active layer.

[0070] By completely covering two surfaces of the second current collector 310 with two layers of the second material layer 320, the volume of the second material layer 320 can be made larger, which is more conducive to the insertion and extraction of metal ions, thereby improving the energy density of the battery cell.

[0071] See Figure 4 , in some embodiments, the positive electrode tab 100 includes a double-sided coating area 100a, a single-sided coating area 100b, and a double-sided empty foil area 100c. One end of the double-sided coating area 100a is the first winding start end, and the other end is connected to the single-sided coating area 100b. The single-sided coating area 100b is located outside the outermost circle of the negative electrode tab 300, and a first material layer 120 is provided on the side of the single-sided coating area 100b facing the negative electrode tab 300. One end of the double-sided empty foil area 100c is connected to the single-sided coating area 100b, and the other end is the winding end of the positive electrode tab 100. The first material layer is a positive electrode active coating.

[0072] By making the positive electrode tab 100 include a double-sided coating area 100a and a single-sided coating area 100b, with one end of the double-sided coating area 100a being the first winding start end and the other end being connected to the single-sided coating area 100b, the first material layer 120 in the double-sided coating area 100a can cooperate with the second material layer 320 of the corresponding negative electrode tab 300 to achieve the insertion and extraction of metal ions. The double-sided coating area 100a is beneficial to increasing the volume ratio of the first material layer 120, thereby improving the energy density of the battery cell. Since the single-sided coating area 100b is located outside the outermost circle of the negative electrode tab 300 and the first material layer 120 is provided on the side of the single-sided coating area 100b facing the negative electrode tab 300, that is, there is no second material layer 320 outside the single-sided coating area 100b. Therefore, by providing the single-sided coating area 100b, the first material layer 120 inside the single-sided coating area 100b can cooperate with the second material layer 320 located outside the outermost circle of the negative electrode tab 300 to achieve the insertion and extraction of metal ions, and no first material layer 120 is provided outside the single-sided coating area 100b, which can improve the utilization rate of the first material layer 120 and reduce the total thickness of the battery cell, being beneficial to improving the energy density of the battery cell. By making the positive electrode tab 100 further include a double-sided empty foil area 100c, with one end of the double-sided empty foil area 100c being connected to the single-sided coating area 100b and the other end being the winding end of the positive electrode tab 100, it is convenient for the positive electrode tab 100 to be wound up and fixed through the double-sided empty foil area 100c.

[0073] See Figure 6 , Figure 6 is a schematic structural diagram of the unfolded positive electrode tab of the battery cell provided in some other embodiments of the present application.

[0074] In some other embodiments, the positive electrode tab 100 includes a double-sided coating area 100a and a single-sided coating area 100b. One end of the double-sided coating area 100a is the first winding start end, and the other end is connected to the single-sided coating area 100b. The end of the single-sided coating area 100b away from the double-sided coating area 100a is the winding end of the positive electrode tab 100. The single-sided coating area 100b is located outside the outermost circle of the negative electrode tab 300, and a first material layer 120 is provided on the side of the single-sided coating area 100b facing the negative electrode tab 300.

[0075] See Figure 1 and Figure 2 , in some embodiments, the electrode assembly 10 includes two layers of separator 200, and the two layers of separator 200 are respectively disposed on both sides of the negative electrode tab 300 along its thickness direction. Along the opposite direction of the winding direction of the electrode assembly 10, the two layers of separator 200 extend beyond the winding start end of the negative electrode tab 300 and are connected.

[0076] By making the electrode assembly 10 include two layers of separator 200, the two layers of separator 200 are respectively disposed on both sides of the negative electrode tab 300 along its thickness direction, and along the opposite direction of the winding direction of the electrode assembly 10, the two layers of separator 200 extend beyond the winding start end of the negative electrode tab 300 and are connected, so that the separator 200 can play an isolation role between the positive electrode tab 100 and the negative electrode tab 300, reducing the risk of contact short circuit between the positive electrode tab 100 and the negative electrode tab 300, and improving the safety of the battery cell.

[0077] See Figure 7 , Figure 7 is a schematic structural diagram of the separator of the battery cell provided by some embodiments of the present application.

[0078] In some embodiments, the separator 200 includes a base layer 210 and two adhesive layers 220, and the two adhesive layers 220 are respectively disposed on both sides of the base layer 210 along its thickness direction.

[0079] By making the separator 200 include a base layer 210 and two adhesive layers 220, and the two adhesive layers 220 are respectively disposed on both sides of the base layer 210 along its thickness direction, the two adhesive layers 220 can be respectively used for bonding with the positive electrode tab 100 and the negative electrode tab 300, and it is not easy for the positive electrode tab 100 to displace relative to the separator 200 and the negative electrode tab 300 to displace relative to the separator 200, so that the overall structure of the electrode assembly 10 is more stable.

[0080] In some embodiments, the base layer 210 may include a polyethylene material, and the adhesive layer 220 may include a polyvinylidene fluoride material.

[0081] By making the base layer 210 include a polyethylene material, the supporting force of the base layer 210 can be made stronger and the stability better. By making the adhesive layer 220 include a polyvinylidene fluoride material, the adhesive force of the adhesive layer 220 can be made stronger.

[0082] In some embodiments, the battery cell further includes a housing (not shown in the figure) and an electrolyte, and the electrode assembly 10 and the electrolyte are accommodated in the housing. The battery cell mainly operates by the movement of metal ions between the positive electrode plate 100 and the negative electrode plate 300. The positive electrode plate 100 includes a positive current collector and a positive active material layer, and the positive active material layer is coated on the surface of the positive current collector. The part of the positive current collector without the positive active material layer is used as the positive electrode tab to realize the input or output of electric energy of the positive electrode plate through the positive electrode tab. Taking a lithium-ion battery as an example, the material of the positive current collector can be aluminum, and the positive active material can be lithium cobaltate, lithium iron phosphate, ternary material, lithium manganate, etc. The negative electrode plate 300 includes a negative current collector and a negative active material layer, and the negative active material layer is coated on the surface of the negative current collector. The part of the negative current collector without the negative active material layer is used as the negative electrode tab to realize the input or output of electric energy of the negative electrode plate through the negative electrode tab. The material of the negative current collector can be copper, and the negative active material can be a carbon material or a silicon material, etc. The material of the separator can be polypropylene (PP) or polyethylene (PE), etc. The electrolyte can include an organic solvent, an electrolyte lithium salt, etc.

[0083] See Figure 1 、 Figure 4 and Figure 5 In some embodiments, the battery cell includes a first electrode tab 510 and a second electrode tab 520. The first electrode tab 510 is connected to the positive electrode plate 100, and the second electrode tab 520 is connected to the negative electrode plate 200.

[0084] The first electrode tab 510 and the positive electrode plate 100 can be welded, riveted, adhered, integrally formed, etc. The second electrode tab 520 and the negative electrode plate 200 can be welded, riveted, adhered, integrally formed, etc.

[0085] The embodiment of the present application provides an electrical device, including the battery cell as described above, and the battery cell is used to provide electric energy.

[0086] The electrical device can be any of the foregoing devices or systems that apply the battery cell.

[0087] It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments can be combined with each other.

[0088] The above are only the preferred embodiments of the present application and are not intended to limit the present application. For those skilled in the art, various changes and modifications can be made to the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included within the protection scope of the present application.

Claims

1. A battery cell, characterized in that: The electrode assembly comprises an electrode assembly, wherein the electrode assembly is formed by winding a stacked positive electrode sheet, a separator, and a negative electrode sheet; The innermost circle of the positive electrode sheet includes a first straight section, a first corner section, and a second straight section, wherein the first corner section connects the first straight section and the second straight section, and an end of the first straight section away from the first corner section is a first winding starting end of the positive electrode sheet; The innermost circle of the negative electrode sheet includes a third straight section, a second corner section and a fourth straight section, the second corner section connects the third straight section and the fourth straight section, and an end of the third straight section away from the second corner section is a second winding starting end of the negative electrode sheet; The positive electrode sheet comprises a first current collector and a first material layer disposed on a surface of the first current collector, the positive electrode sheet has a first groove in the first corner section, the first current collector has a first area, and along the width direction of the electrode assembly, the first groove is opposite to the second winding start end; The first groove includes a first sub-groove and a second sub-groove that penetrates the first sub-groove to the first current collector, and the first region is exposed in the second sub-groove; The adhesive component is disposed in the second sub-groove and at least partially covers the first sub-groove.

2. The battery cell according to claim 1, characterized in that: Along the width direction of the electrode assembly, the first starting end and the second starting end are respectively located on both sides of the center of the battery cell, the first winding starting end is opposite to the second corner section, and the second winding starting end is opposite to the first corner section.

3. The battery cell according to claim 1, characterized in that: Along the winding direction of the electrode assembly, the width of the first region is W, satisfying 1 mm ≤ W ≤ 25 mm.

4. The battery cell according to claim 1, characterized in that: Along the winding direction of the electrode assembly, at least one end of the adhesive is disposed on the first material layer.

5. The battery cell according to claim 1, characterized in that: Along the winding direction of the electrode assembly, the first sub-groove has a first side wall and a second side wall, the spacing distance between the first end of the adhesive and the first side wall is D1, satisfying D1≥0; the spacing distance between the second end of the adhesive and the second side wall is D2, satisfying D2≥0.

6. The battery cell according to claim 1, characterized in that: The thickness of the first material layer located in the first sub-groove is H1, the thickness of the adhesive is H2, and the maximum thickness of the first material layer is H3, satisfying H1+H2≤H3.

7. The battery cell according to claim 1, characterized in that: Along the width direction of the electrode assembly, the bonding member and the third straight section have an overlapping area; The length of the overlapping area is L1, satisfying L1≥0.5 mm.

8. The battery cell according to claim 1, characterized in that: The negative electrode plate includes a second current collector and two second material layers, and the two surfaces of the second current collector are completely covered with the two second material layers.

9. The battery cell according to claim 1, characterized in that: The electrode assembly comprises two layers of the separator, and the two layers of the separator are respectively arranged on both sides of the negative electrode sheet along the thickness direction thereof; Along the opposite direction of the winding direction of the electrode assembly, the two layers of the separator exceed the winding starting end of the negative electrode plate and are connected.

10. An electrical device, characterized in that: The invention comprises a battery cell as described in any one of claims 1 to 9, wherein the battery cell is used to provide electrical energy.

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