Electrode assembly, method for preparing electrode assembly, battery and battery module

Abstract

The present invention belongs to the technical field of battery production and manufacturing, and specifically relates to an electrode assembly, a method for preparing an electrode assembly, a battery and a battery module. The electrode assembly includes a battery cell, and the battery cell includes a positive electrode sheet, a negative electrode sheet and a separator arranged between the positive electrode sheet and the negative electrode sheet. The positive electrode sheet and / or the negative electrode sheet are provided with a coating area and a hollow foil area, and the hollow foil area is folded in n layers toward the coating area to form a pole ear portion, n≥2, and the positive projections of the pole ear portion and the coating area on the xoy plane do not overlap, and the end face of the pole ear portion is used to achieve electrical connection; the folding method is adopted to replace the existing rubbing of the pole ear, which can not only prevent the generation of metal debris in the process of rubbing the pole ear, resulting in a short circuit of the battery cell, but also enhance the thickness and strength of the pole ear, solve the problem that the pole ear is easily folded and wrinkled during high-speed winding, and effectively optimize the safety performance of the battery cell.

Description

Technical Field

[0001] The present invention belongs to the technical field of battery production and manufacturing, and specifically relates to an electrode assembly, a method for preparing the electrode assembly, a battery and a battery module. Background Art

[0002] Nowadays, with the rapid growth of population and the rapid development of social economy, resources and energy are becoming increasingly scarce, environmental protection is increasingly valued, and the development and conservation of energy has become an important issue in today's world. Energy is the basis for the existence and development of human society. Today's society based on mineral energy is increasingly facing energy shortages and environmental pollution crises. At the same time, with the advent of the information and high-tech era, the form of energy application is changing, and the demand for renewable, pollution-free, small and discrete mobile high-performance power sources is growing rapidly. All countries are vigorously developing green and efficient secondary batteries. As a new type of secondary battery, lithium-ion batteries have the advantages of high energy density and power density, high operating voltage, light weight, small size, long cycle life, good safety, and green environmental protection. They have broad application prospects in portable appliances, power tools, large energy storage, and electric transportation power sources.

[0003] Existing cylindrical batteries generally use a tab kneading method to knead the tab into a flat surface and then electrically connect the processed tab to the busbar. However, in the process of kneading the tab, metal debris is easily generated, which can easily cause a short circuit in the battery cell. Summary of the invention

[0004] One of the purposes of the present invention is to provide an electrode assembly to address the deficiencies of the prior art and to solve the problem in the prior art that metal debris generated by rubbing the tabs easily leads to short circuits in the battery cells.

[0005] In order to achieve the above object, the present invention adopts the following technical solution:

[0006] An electrode assembly comprises a battery cell, wherein the battery cell comprises a positive electrode sheet, a negative electrode sheet and a separator arranged between the positive electrode sheet and the negative electrode sheet, wherein the positive electrode sheet and / or the negative electrode sheet is provided with a coating area and a hollow foil area, wherein the hollow foil area is folded in n layers toward the coating area to form a pole ear portion, where n≥2, and the orthographic projections of the pole ear portion and the coating area in the xoy plane do not overlap, and the end face of the pole ear portion is used to achieve electrical connection.

[0007] Preferably, the end surface of the pole lug portion is a plane.

[0008] Preferably, the pole ear portion includes a positive pole ear portion and a negative pole ear portion, and the positive pole ear portion and the negative pole ear portion are respectively arranged at two ends of the battery cell, or the positive pole ear portion and the negative pole ear portion are located on the same end surface of the battery cell.

[0009] Preferably, each layer of the pole tabs of the pole tab portion are connected to each other.

[0010] Another object of the present invention is to provide a method for preparing an electrode assembly, comprising the following steps:

[0011] Providing a coating area and a hollow foil area on the positive electrode sheet and / or the negative electrode sheet;

[0012] Fold the empty foil area toward the coated area in n layers to form a pole ear, where n≥2.

[0013] Preferably, after the empty foil area is folded to form the pole ear portion, the pole ear portion is pre-welded or bonded.

[0014] Preferably, the empty foil area is folded n layers along one or more folds toward the coating area to form the pole ear portion; or, the empty foil area is folded n layers toward the coating area to form the pole ear portion.

[0015] Another object of the present invention is to provide a battery, comprising a shell, a cover plate and an electrode assembly as described above in the specification, wherein the shell has an opening, the cover plate seals the opening and forms a cavity between the cover plate and the shell, and the electrode assembly is arranged in the cavity.

[0016] Another object of the present invention is to provide a battery module, comprising the battery described above in the specification.

[0017] The beneficial effect of the present invention is that the present invention provides an electrode assembly, in which a coating area and a hollow foil area are provided on the positive electrode sheet and / or the negative electrode sheet, and the hollow foil area is folded in n layers toward the coating area to form a pole ear portion, and a folding method is adopted to replace the existing rubbing of the pole ear, which can prevent the generation of metal debris in the process of rubbing the pole ear, resulting in a short circuit of the battery cell, and can also increase the thickness and strength of the pole ear, thereby solving the problem that the pole ear is easily folded and wrinkled during high-speed winding, and effectively optimizing the safety performance of the battery cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Features, advantages, and technical effects of exemplary embodiments of the present invention will be described below with reference to the accompanying drawings.

[0019] Figure 1 It is a schematic diagram of the structure of the battery cell in the present invention.

[0020] Figure 2 for Figure 1 A magnified schematic diagram of center A.

[0021] Figure 3 for Figure 1 A magnified schematic diagram of point B in the middle.

[0022] Figure 4 It is a schematic diagram of the cross-sectional structure of the battery cell in the present invention.

[0023] Figure 5 for Figure 4 Enlarged schematic diagram of point C in the middle.

[0024] Figure 6 Another structural schematic diagram of the battery cell in the present invention.

[0025] Figure 7 It is a schematic diagram of the structure of the hollow foil area before folding of the present invention.

[0026] Figure 8 It is a schematic diagram of the structure of the hollow foil area after folding of the present invention.

[0027] Fig. 9 It is another schematic diagram of the structure of the hollow foil area after folding of the present invention.

[0028] Fig.10 It is another structural schematic diagram of the hollow foil area after folding of the present invention.

[0029] Fig.11 It is another structural schematic diagram of the hollow foil area after folding of the present invention.

[0030] Fig.12 It is a schematic diagram of the structure of the positive electrode sheet in the present invention.

[0031] The reference numerals are described as follows:

[0032] 100. Battery cell;

[0033] 10. Positive electrode;

[0034] 20. Negative electrode;

[0035] 30. Diaphragm;

[0036] 40, empty foil area; 43, crease; 44, folding area;

[0037] 50. Coating area;

[0038] 60. Pole ear portion; 61. Positive pole ear portion; 62. Negative pole ear portion; 63. End face of the pole ear portion. DETAILED DESCRIPTION

[0039] For example, certain words are used in the specification and claims to refer to specific components. Those skilled in the art should understand that hardware manufacturers may use different terms to refer to the same component. This specification and claims do not use differences in names as a way to distinguish components, but use differences in the functions of components as the criteria for distinction. For example, "including" mentioned throughout the specification and claims is an open term, so it should be interpreted as "including but not limited to". "Approximately" means that within an acceptable error range, those skilled in the art can solve technical problems within a certain error range and basically achieve technical effects.

[0040] Furthermore, the terms “first”, “second”, etc. are used for descriptive purposes only and are not to be understood as indicating or implying relative importance.

[0041] Reference to "embodiments" in the present invention means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present invention. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments.

[0042] In the invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the invention can be understood according to specific circumstances.

[0043] The term "and / or" in the present invention is only a description of the association relationship of the associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in the present invention generally indicates that the associated objects before and after are in an "or" relationship.

[0044] The term "plurality" used in the present invention refers to two or more (including two).

[0045] The x-axis, y-axis and z-axis in the present invention are perpendicular to each other and intersect at point o.

[0046] In addition, the expressions of the indicated directions, such as the X-axis, Y-axis, and Z-axis, used to illustrate the operation and construction of the various components of the battery of this embodiment are not absolute but relative, and although these indications are appropriate when the various components of the battery are in the positions shown in the figures, when these positions change, these directions should be interpreted differently to correspond to these changes.

[0047] The battery module mentioned in the embodiments of the present invention refers to a single physical module including one or more batteries to provide higher voltage and capacity. For example, the battery module mentioned in the present invention may include a battery module or a battery pack. The battery module generally includes a box for encapsulating one or more batteries. The box can prevent liquid or other foreign matter from affecting the charging or discharging of the battery.

[0048] The following is combined with Figures 1 to 12 The present invention is further described in detail, but is not intended to limit the present invention.

[0049] See also Figures 1 to 10 An embodiment of the present invention provides an electrode assembly, including a battery cell 100, wherein the battery cell 100 includes a positive electrode sheet 10, a negative electrode sheet 20, and a separator 30 arranged between the positive electrode sheet 10 and the negative electrode sheet 20, wherein the positive electrode sheet 10 and / or the negative electrode sheet 20 is provided with a coating area 50 and a hollow foil area 40, wherein the hollow foil area 40 is folded in n layers toward the coating area 50 to form a pole ear portion 60, where n≥2, and the orthographic projections of the pole ear portion 60 and the coating area 50 in the xoy plane do not overlap, and the end surface 63 of the pole ear portion 60 is used to achieve electrical connection.

[0050] Compared with the prior art, an embodiment of the present invention provides an electrode assembly, in which a coating area 50 and a hollow foil area 40 are provided on the positive electrode sheet 10 and / or the negative electrode sheet 20, and the hollow foil area 40 is folded in n layers toward the coating area 50 to form a pole ear portion 60. The folding method is used to replace the existing kneading of the pole ear, which can prevent the generation of metal debris during the kneading of the pole ear, resulting in a short circuit of the battery cell 100, and can also increase the thickness and strength of the pole ear, thereby solving the problem that the pole ear is easily folded and wrinkled during high-speed winding, and effectively optimizing the safety performance of the battery cell 100.

[0051] It should be noted that the pole ear portion 60 is the portion of the end surface of the positive electrode sheet 10 protruding from the end surface of the negative electrode sheet 20; and / or, the portion of the end surface of the negative electrode sheet 20 protruding from the end surface of the positive electrode sheet 10. The pole ear portion 60 is used to be electrically connected to the cover plate or the housing or the pole.

[0052] It should be noted that the width D of the empty foil area 40 is greater than or equal to 3 mm. When used, it can be set according to actual needs.

[0053] The thickness b of the pole ear portion 60 of the embodiment of the present invention satisfies the following relationship:

[0054] b≤1.2(h1+h2+h3), wherein h1 is the thickness of the positive electrode sheet 10 , h2 is the thickness of the negative electrode sheet 20 , and h3 is the thickness of the separator 30 .

[0055] After many experiments by the inventors of the present invention, it is found that the optimal choice of the thickness b of the pole ear portion 60 is 2a≤b≤1.2(h1+h2+h3), where a is the thickness of the empty foil area 40. When b≥2a, that is, n≥2, after winding, the structure of the pole ear portion 60 can be more compact, not easy to loosen, and easy to weld. When b>1.2(h1+h2+h3), the diameter of the battery cell 100 at the pole ear portion 60 is larger than the diameter of the middle part of the battery cell 100. When the battery cell 100 is encapsulated in the battery, the battery shell needs to consider the diameter of the battery cell 100 at the pole ear portion 60 to ensure that the battery cell 100 can be placed in the shell, which results in a large gap between the other parts of the battery cell 100 and the shell. Even if the battery cell 100 expands later, it is difficult to fill the gap, thereby reducing the energy density of the battery. Therefore, when 2a≤b≤1.2(h1+h2+h3), the strength of the thickness b of the pole ear portion 60 can be ensured, the structure is compact, and welding is convenient, while the energy density of the battery can be improved.

[0056] The inventors found that after the hollow foil area 40 is folded, the positive electrode sheet 10, the separator 30 and the negative electrode sheet 20 are stacked and wound in sequence to form the battery cell 100, so that the pole ear portion 60 forms a gap in the direction of the y-axis for accommodating the passage of electrolyte, and the upper ends of the pole ear portions 60 are located in the same plane. Effectively ensuring that the upper ends of the pole ears are located in the same plane is more conducive to the welding of the pole ear portion 60 and the busbar, and at the same time, it can ensure that the electrolyte can pass through the gap to achieve the purpose of infiltrating the battery cell 100, thereby improving the energy density of the battery cell 100.

[0057] The inventors have also found that when the hollow foil area 40 is folded, the broken end of the hollow foil area 40 is easy to contact with the coating area 50, thereby affecting the active material in the coating area 50, and causing the performance of the battery to deteriorate after the battery is subsequently manufactured. Therefore, the inventors set an exposed area between the hollow foil area 40 and the coating area 50 to prevent the broken end of the hollow foil area 40 from contacting with the active material in the coating area 50, which affects the subsequent use of the battery. At the same time, an insulating layer can also be coated on the exposed area, and the material of the insulating layer is ceramic or organic polymer.

[0058] See also Fig.11 In the embodiment of the present invention, the end face 63 of the pole ear portion 60 is a plane. By setting the end face 63 of the pole ear portion 60 as a plane, compared with the curved surface, when the plane is connected with the cover plate, the housing, the pole column or the collector plate, the contact area is larger, which effectively improves the current flow capacity of the pole ear portion.

[0059] It should be noted that when the end surface 63 of the pole lug portion 60 is a plane, the end surface 63 of the pole lug portion 60 and the xoz plane are parallel to each other.

[0060] See also Fig.12In the embodiment of the present invention, a plurality of empty foil areas 40 are provided, and the plurality of empty foil areas 40 are sequentially spaced and arranged on the positive electrode sheet 10 and / or the negative electrode sheet 20 along the x-axis direction. By providing a plurality of empty foil areas 40, the distance between two adjacent empty foil areas 40 can be set according to actual needs. At the same time, by adjusting the distance between the plurality of empty foil areas 40, it is possible to effectively prepare for the positive electrode ear portion 61 and the negative electrode ear portion 62 to be located on the same end surface of the battery cell 100.

[0061] It should be noted that the positive electrode sheet 10 includes a positive electrode current collector and a positive electrode active material layer, the negative electrode sheet 20 includes a negative electrode current collector and a negative electrode active material layer, the coating area 50 includes a positive electrode coating area and a negative electrode coating area, the empty foil area 40 includes a positive electrode empty foil area and a negative electrode empty foil area, the positive electrode coating area and the positive electrode empty foil area are arranged on the positive electrode current collector, the positive electrode active material layer is coated on the positive electrode coating area, the negative electrode coating area and the negative electrode empty foil area are arranged on the negative electrode current collector, and the negative electrode active material layer is coated on the negative electrode coating area. Taking lithium-ion batteries as an example, the material of the positive electrode current collector can be aluminum, the positive electrode active material layer includes a positive electrode active material, and the positive electrode active material can be lithium cobalt oxide, lithium iron phosphate, ternary lithium or lithium manganate, etc. The material of the negative electrode current collector can be copper, the negative electrode active material layer includes a negative electrode active material, and the negative electrode active material can be carbon or silicon, etc. The material of the separator can be PP (polypropylene, polypropylene) or PE (polyethylene, polyethylene), etc.

[0062] See also Figures 1 to 6 The pole ear portion 60 of the embodiment of the present invention includes a positive pole ear portion 61 and a negative pole ear portion 62, and the positive pole ear portion 61 and the negative pole ear portion 62 are respectively arranged at the two ends of the battery cell 100, or the positive pole ear portion 61 and the negative pole ear portion 62 are located on the same end surface of the battery cell 100. Through the arrangement of the positive pole ear portion 61 and the negative pole ear portion 62, the battery cell 100 can be connected to the corresponding bus bar through the positive pole ear portion 61 and the negative pole ear portion 62 respectively. Compared with the positive pole ear portion 61 and the negative pole ear portion 62 being respectively arranged at the two ends of the battery cell 100, when the positive pole ear portion 61 and the negative pole ear portion 62 are located on the same end surface of the battery cell 100, the height of the battery cell 100 is reduced, which can effectively improve the energy density of the battery.

[0063] It should be noted that the positive electrode ear 61 can be directly welded to the cover plate or the shell, or welded to the cover plate or the shell through a current collecting plate; the negative electrode ear 62 can be directly welded to the cover plate or the shell, or welded to the cover plate or the shell through a current collecting plate.

[0064] Each layer of the pole lugs 60 of the embodiment of the present invention is connected to each other. By connecting each layer of the pole lugs to each other, the pole lugs 60 formed after folding are effectively fixed to prevent the pole lugs 60 formed after folding from becoming loose, which is inconvenient for the preparation of the battery cell.

[0065] It should be noted that each layer of tabs can be fixed by welding or bonding to prevent them from loosening.

[0066] Another embodiment of the present invention provides a method for preparing an electrode assembly, comprising the following steps:

[0067] A coating area 50 and a hollow foil area 40 are provided on the positive electrode sheet 10 and / or the negative electrode sheet 20;

[0068] The empty foil area 40 is folded in n layers toward the coating area 50 to form a pole ear portion 60, where n≥2.

[0069] Compared with the prior art, another embodiment of the present invention provides a method for preparing an electrode assembly, by providing a coating area 50 and a hollow foil area 40 on the positive electrode sheet 10 and / or the negative electrode sheet 20, and folding the hollow foil area 40 to form a pole ear portion 60. The folding method is used to replace the existing rubbing of the pole ear, which can not only prevent the generation of metal debris during the rubbing of the pole ear, resulting in a short circuit of the battery cell 100, but also increase the thickness and strength of the pole ear, solve the problem that the pole ear is prone to folding and wrinkling during high-speed winding, and effectively optimize the safety performance of the battery cell 100.

[0070] In another embodiment of the present invention, after the empty foil area 40 is folded to form the pole ear portion 60, the pole ear portion 60 is pre-welded or bonded. By pre-welding or bonding, the pole ear portion 60 formed after the empty foil area 40 is folded is pre-welded, and the pole ear portion 60 of the multi-layer structure is effectively fixed to prevent the pole ear portion 60 from being loose, which is inconvenient for the subsequent preparation of the battery cell.

[0071] See also Figures 7-10 In another embodiment of the present invention, the empty foil area 40 is folded n layers along one or more folds 43 toward the coating area 50 to form the pole ear portion 60; or, the empty foil area 40 is folded n layers toward the coating area 50 to form the pole ear portion 60. By folding or folding the empty foil area 40 along the fold 43 to form the pole ear portion 60, there is no need to rub the pole ear, so as to prevent metal debris generated during the rubbing of the pole ear from falling into the battery cell 100 and causing the battery cell 100 to short-circuit.

[0072] It should be noted that one or more folds 43 are sequentially arranged on the empty foil area 40 along the y-axis direction, and the empty foil area 40 is divided into a plurality of folding areas 44, and the plurality of folding areas 44 are folded toward the coating area 50 along the one or more folds 43 to form the pole ear portion 60. The number of folds 43 can be set according to the number of layers to be folded.

[0073] Furthermore, the width K of the folding area 44 satisfies the following relationship:

[0074] 0<K≤1 / 2D, where D is the width of the empty foil area 40. By setting the width K of the folding area 44, the width K of the folding area 44 satisfies the following relationship: 0≤K≤1 / 2D. When K=1 / 2D, the folding area 44 is folded along the fold 43 to form the pole ear portion 60. When in use, the width K of the folding area 44 can be set according to the position of the fold 43 and the distance between two adjacent folds 43.

[0075] Furthermore, the orthographic projections of the multiple folding areas 44 overlap with each other. When the orthographic projections of the multiple folding areas 44 overlap with each other, the widths K of the multiple folding areas 44 are the same, so that after the empty foil area 40 is folded, the upper and lower end surfaces of the pole ear portion 60 are relatively neat, which effectively facilitates the welding of the pole ear portion 60 with the bus bar, while preventing the lower end of the pole ear portion 60 from contacting the active material of the coating area 50 to affect the performance of the battery.

[0076] It should be noted that when folding the empty foil area 40, the empty foil area 40 can be folded according to the folding line 43, or the empty foil area 40 can be folded in n layers, or the two folding methods can be mixed and used. When using, the folding method can be adjusted according to actual needs.

[0077] It should be noted that the method for preparing an electrode assembly according to another embodiment of the present invention further includes the following steps:

[0078] The positive electrode active material is coated on the positive electrode coating area of ​​the positive electrode current collector to obtain a positive electrode sheet 10, and the negative electrode active material is coated on the negative electrode coating area of ​​the negative electrode current collector to obtain a negative electrode sheet 20;

[0079] After the electrode lugs 60 are pre-welded or bonded, the positive electrode sheets 10 , the separators 30 , and the negative electrode sheets 20 are stacked in sequence and wound to obtain the battery cell 100 .

[0080] It should be noted that when the battery cell 100 has multiple tabs, the positive electrode empty foil portion and the negative electrode empty foil portion can be die-cut to obtain a plurality of spaced positive electrode empty foil areas and a plurality of spaced negative electrode empty foil areas, and then each positive electrode empty foil portion and each negative electrode empty foil portion can be folded;

[0081] Alternatively, the positive electrode empty foil area and the negative electrode empty foil area are first folded to obtain the positive electrode ear portion 61 and the negative electrode ear portion 62, and then the positive electrode ear portion 61 and the negative electrode ear portion 62 are die-cut to obtain multiple positive electrode ear portions 61 and multiple negative electrode ear portions 62. The method of die-cutting first and then folding has higher precision than the square formed by folding first and then die-cutting, because the thickness of the positive electrode ear portion 61 and the negative electrode ear portion 62 after folding is greater than that of the positive electrode empty foil area and the negative electrode empty foil area, which will affect the precision of die-cutting to a certain extent.

[0082] Another embodiment of the present invention provides a battery, including a shell, a cover plate and the electrode assembly mentioned in the above embodiment, the shell has an opening, the cover plate seals the opening, and a cavity is formed between the shell and the cover plate, and the battery cell 100 is disposed in the cavity.

[0083] Compared with the prior art, another embodiment of the present invention provides a battery, through the use of a shell, a cover plate and the electrode assembly mentioned in the above embodiment, the shell has an opening, the cover plate seals the opening, and a cavity is formed between the shell and the cover plate, and the electrode assembly is arranged in the cavity. The pole ear portion 60 of the electrode assembly adopts a folding method to replace the existing rubbing pole ear, which can not only prevent the generation of metal debris during the rubbing of the pole ear, resulting in a short circuit of the battery cell 100, but also increase the thickness and strength of the pole ear, solve the problem that the pole ear is easy to fold and wrinkle during high-speed winding, and effectively optimize the safety performance of the battery cell 100, thereby improving the safety of the battery.

[0084] It should be noted that the shell includes a side wall and a bottom wall, the side wall surrounds the outside of the electrode assembly, and the bottom wall is connected to the other end of the side wall away from the outlet. The side wall is a cylindrical structure, and the bottom wall is a plate-like structure, and its shape corresponds to the shape of the side wall.

[0085] Further, the side wall and the bottom wall can be an integrally formed structure, that is, the housing is an integrally formed component. Of course, the side wall and the bottom wall can also be two components provided separately and then connected together by welding.

[0086] Furthermore, the cover plate can be installed on the opening of the shell by welding or a sealing process. When the sealing process is adopted, the side wall includes a curling portion formed at the lower part of the cover plate and a crimping portion formed at the upper part of the cover plate that bends inwards. Before the battery is sealed, a curling portion needs to be provided on the side wall to prepare for the battery sealing and to limit the battery cell 100. After the battery is sealed, a crimping portion of the upper part of the cover plate that bends inwards is formed on the side wall.

[0087] It should be noted that when the positive pole ear 61 and the negative pole ear 62 are located on the same end surface of the battery cell 100, an insulating member can be provided between the positive pole ear 61 and the negative pole ear 62 to prevent the positive pole ear 61 from contacting the negative pole ear 62 and causing a short circuit in the battery cell 100.

[0088] Another embodiment of the present invention provides a battery module, including the battery described above, and the battery is used to provide electrical energy.

[0089] Compared with the prior art, another embodiment of the present invention provides a battery module, which includes the battery mentioned in the above embodiment. The battery has higher safety performance and effectively improves the safety of the battery module.

[0090] It should be noted that the battery module also includes a box body, in which the battery is accommodated, and the box body can have various structures.

[0091] It should be noted that there can be multiple batteries, and the multiple batteries can be connected in series, in parallel, or in a mixed connection. Mixed connection means that multiple batteries are connected in series and in parallel. Multiple batteries can be directly connected in series, in parallel, or in a mixed connection, and then the whole formed by the multiple batteries is accommodated in the box; of course, multiple batteries can also be connected in series, in parallel, or in a mixed connection to form a battery module, and then the multiple battery modules are connected in series, in parallel, or in a mixed connection to form a whole, and are accommodated in the box. In some embodiments, there are multiple batteries, and multiple batteries are first connected in series, in parallel, or in a mixed connection to form a battery module. Multiple battery modules are then connected in series, in parallel, or in a mixed connection to form a whole, and are accommodated in the box.

[0092] According to the disclosure and teaching of the above description, those skilled in the art to which the present invention belongs can also change and modify the above embodiment. Therefore, the present invention is not limited to the above specific embodiment, and any obvious improvement, replacement or modification made by those skilled in the art on the basis of the present invention belongs to the protection scope of the present invention. In addition, although some specific terms are used in this specification, these terms are only for the convenience of description and do not constitute any limitation to the present invention.

Claims

1. An electrode assembly, characterized in that: The invention comprises a battery cell (100), wherein the battery cell (100) is configured to be accommodated in a cavity formed between a cover plate and a shell; the battery cell (100) comprises a positive electrode sheet (10), a negative electrode sheet (20), and a separator (30) arranged between the positive electrode sheet (10) and the negative electrode sheet (20); the positive electrode sheet (10) and / or the negative electrode sheet (20) are provided with a coating area (50) and a hollow foil area (40), wherein a bare area is provided between the hollow foil area (40) and the coating area (50), and an insulating layer is coated on the bare area; The foil area (40) is folded in n layers toward the coating area (50) to form a pole ear portion (60), where n≥2. The orthographic projections of the pole ear portion (60) and the coating area (50) on the xoy plane do not overlap. The end surface of the pole ear portion (60) is used to achieve electrical connection. The thickness b of the pole ear portion (60) satisfies the following relationship: 2a≤b≤1.2(h1+h2+h3), wherein a is the thickness of the empty foil area, h1 is the thickness of the positive electrode sheet (10), h2 is the thickness of the negative electrode sheet (20), and h3 is the thickness of the diaphragm (30).

2. An electrode assembly according to claim 1, characterized in that: A plurality of the empty foil areas (40) are provided, and the plurality of the empty foil areas (40) are sequentially spaced apart and arranged on the positive electrode sheet (10) and / or the negative electrode sheet (20) along the x-axis direction.

3. An electrode assembly according to claim 1, characterized in that: The end surface (63) of the pole ear portion (60) is a plane.

4. An electrode assembly according to claim 1, characterized in that: The pole ear portion (60) comprises a positive pole ear portion (61) and a negative pole ear portion (62); the positive pole ear portion (61) and the negative pole ear portion (62) are respectively arranged at two ends of the battery cell (100); or the positive pole ear portion (61) and the negative pole ear portion (62) are located on the same end surface of the battery cell (100).

5. An electrode assembly according to claim 1, characterized in that: Each layer of the pole tabs of the pole tab portion is connected to each other.

6. A method for preparing an electrode assembly according to any one of claims 1 to 5, characterized in that: The following steps are involved: A coating area (50) and a hollow foil area (40) are provided on the positive electrode sheet (10) and / or the negative electrode sheet (20); The empty foil area (40) is folded in n layers towards the coating area (50) to form a pole ear portion (60), where n≥2.

7. A method for preparing an electrode assembly according to claim 6, characterized in that: After the empty foil area (40) is folded to form the pole ear portion (60), the pole ear portion (60) is pre-welded or bonded.

8. The method for preparing an electrode assembly according to claim 6, characterized in that: Folding the empty foil area along one or more folds toward the coated area in n layers to form a pole ear portion; Alternatively, the empty foil area is folded toward the coated area by n layers to form the pole ear portion.

9. A battery, characterized in that: The invention comprises a shell, a cover plate and the electrode assembly according to any one of claims 1 to 5, wherein the shell has an opening, the cover plate seals the opening and forms a cavity between the cover plate and the shell, and the electrode assembly is arranged in the cavity.

10. A battery module, characterized in that: A battery comprising the battery described in claim 9.

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