Secondary battery and electronic device

Abstract

The invention discloses a secondary battery and an electronic device. The secondary battery comprises an electrode assembly, a structural member and a packaging bag, the electrode assembly is bent towards the first direction and comprises m electrode units, m is an integer larger than or equal to 1, each electrode unit comprises a first wall and a second wall which are sequentially arranged in the first direction, and the first walls and the second walls are bent towards the first direction. The structural member is bent towards the first direction, the structural member is fixed to the electrode assembly, and the structural member is attached to at least one of the first wall and the second wall of the electrode unit. The packaging bag is used for accommodating the electrode assembly and the structural member. Force generated by the bent electrode unit in the flattening trend is transmitted to the structural part through the packaging bag, the structural part counteracts at least part of the force transmitted by the packaging bag, and therefore deformation of the electrode unit is restrained.

Description

Secondary battery and electronic device Technical Field

[0001] The present application relates to the field of energy storage technology, and in particular to a secondary battery and an electronic device. Background Art

[0002] Currently, to accommodate various electronic device shapes, battery shapes are also changing accordingly. For example, batteries designed for curved electronic devices are often designed as curved batteries. However, curved batteries suffer from deformation issues such as curvature reduction and flattening. Therefore, a secondary battery that can alleviate these issues is urgently needed.

[0003] Summary of the Invention

[0004] In view of this, the present application provides a secondary battery capable of suppressing deformation of an electrode unit.

[0005] Some embodiments of the present application provide a secondary battery, which includes an electrode assembly, a structural member, and a packaging bag. The electrode assembly is bent toward a first direction, and the electrode assembly includes m electrode units, where m is an integer greater than or equal to 1, and the electrode unit includes a first wall and a second wall sequentially arranged in the first direction, and both the first wall and the second wall are bent toward the first direction. The structural member is bent toward the first direction, and the structural member is fixed to the electrode assembly, and the structural member is arranged at least one of the first wall and the second wall of the electrode unit. The packaging bag is used to accommodate the electrode assembly and the structural member. The number of structural members is n, where n is an integer greater than or equal to 1, and the electrode assembly and the structural member satisfy the following formula:

[0006] Among them, W m represents the width of the mth electrode unit in the second direction perpendicular to the first direction, Cm represents the length of the mth electrode unit bent and extended when viewed along the second direction, D m represents the thickness of the mth electrode unit in the first direction; B n Indicates the width of the nth structural member in the second direction, L n H represents the length of the nth structural member bent and extended when viewed along the second direction. n represents the thickness of the nth structural member in the first direction; σ n Indicates: the bending strength of the nth structural member.

[0007] The above-mentioned curved structural member is fixed to the electrode unit of the electrode assembly to offset at least part of the force generated by the electrode unit's deformation tendency due to curvature reduction and equalization, and the force generated by the deformation of the electrode unit is also transmitted to the structural member through the packaging bag. The structural member offsets at least part of the force transmitted from the packaging bag, thereby playing a role in suppressing the deformation of the electrode unit. On the premise of satisfying the above formula, it is beneficial to make the curvature radius change rate of the electrode unit less than 4%, thereby reducing the risk of lithium plating in the electrode assembly and reducing the reserved space of the battery compartment for accommodating secondary batteries. It is also beneficial to use fixtures in the production process, thereby facilitating the production and installation of secondary batteries, and improving the reliability and applicability of secondary batteries.

[0008] In some embodiments, the electrode assembly has a first width T along the second direction, a first length P of the electrode assembly bent and extended when viewed along the second direction, and 2 / 3×T≤B n ≤T and 2 / 3×P≤L n ≤P.

[0009] The above arrangement helps reduce the space occupied by the structural member, allowing the structural member to not extend beyond the electrode assembly in the second direction or in the bending direction of the electrode assembly when viewed along the second direction. This, in turn, helps prevent the structural member from occupying space in the secondary battery in the second direction or in the bending direction of the electrode assembly when viewed along the second direction. When a structural member is connected to an electrode unit, this helps increase the area available for bonding and connection between the electrode unit and the structural member, thereby reducing the risk of poor connection between the structural member and the electrode unit, such as reduced connection area and detachment. Furthermore, increasing the length and width of the structural member helps improve the structural member's ability to suppress deformation of the electrode unit.

[0010] In some embodiments, the secondary battery further includes a first adhesive layer, and the structural member is fixed to the electrode assembly through the first adhesive layer.

[0011] The first adhesive layer is beneficial to improving the tightness of fixing the structural member and the electrode assembly, and is beneficial to improving the ability of the structural member to suppress deformation of the electrode unit.

[0012] In some embodiments, m=1, n=1, and the structural member is disposed on the second wall of the electrode unit.

[0013] The curved structural member, coupled to the second wall of the electrode unit, can directly offset at least part of the force generated by the electrode unit's deformation tendency, thereby suppressing deformation of the electrode unit. The second wall is concave, and the placement of the structural member on the second wall provides a protective layer between the electrode unit and the human body, reducing the risk of injury from damage to the electrode unit and further improving the reliability of the secondary battery.

[0014] In some embodiments, the packaging bag includes a third wall and a fourth wall sequentially arranged in the first direction, the third wall is at least partially in contact with the first wall, and the fourth wall is at least partially in contact with the structural member.

[0015] The above-mentioned third wall is at least partially in contact with the first wall, and the fourth wall is at least partially in contact with the structural part, so that the third wall and the fourth wall of the packaging bag are in direct contact with the electrode unit and the structural part, which is conducive to allowing the force generated by the deformation tendency of the electrode unit to be directly transmitted to the structural part through the packaging bag, thereby helping the structural part to offset the force generated by the electrode unit, thereby improving the effect of the structural part in suppressing the deformation of the electrode unit.

[0016] In some embodiments, the secondary battery further includes a second adhesive layer, the packaging bag includes a third wall and a fourth wall sequentially arranged in the first direction, the third wall is at least partially in contact with the first wall, and the fourth wall is bonded to the structural member through the second adhesive layer.

[0017] The above-mentioned third wall is at least partially in contact with the first wall, so that the third wall of the packaging bag is in direct contact with the electrode unit and the structural part, which is beneficial for the force generated by the deformation tendency of the electrode unit to be directly transmitted to the structural part through the packaging bag, thereby helping the structural part to offset the force generated by the electrode unit, and further improve the effect of the structural part in suppressing the deformation of the electrode unit. The fourth wall and the structural part are bonded by the second adhesive layer, which is beneficial for improving the tightness and drop performance of the combination between the fourth wall and the structural part, and reducing the mutual movement and friction between the structural part and the packaging bag.

[0018] In some embodiments, the packaging bag is made of at least one of aluminum-plastic film or steel-plastic film.

[0019] In some embodiments, the packaging bag includes a third wall and a fourth wall sequentially arranged in the first direction, both the third wall and the fourth wall are bent toward the first direction, the third wall is made of aluminum-plastic film, and the fourth wall is made of steel-plastic film.

[0020] The bending strength of the above-mentioned steel-plastic film is greater than that of the aluminum-plastic film. The fourth wall that is in contact with the structural member is made of steel-plastic film. When the force generated by the deformation tendency of the electrode unit is transmitted to the third wall of the aluminum-plastic film, the third wall transmits the force to the fourth wall of the steel-plastic film. The bending strength of the fourth wall of the steel-plastic film is greater than that of the third wall of the aluminum-plastic film, which can offset at least part of the force transmitted by the third wall, so that the fourth wall can play a role in suppressing the deformation of the electrode unit, which is beneficial to reducing the thickness of the structural member in the first direction and improving the energy density of the secondary battery.

[0021] In some embodiments, the electrode unit includes a first electrode plate, a second electrode plate and a diaphragm arranged between the first electrode plate and the second electrode plate, and the first electrode plate, the diaphragm and the second electrode plate are stacked to form a laminated structure; or the first electrode plate, the diaphragm and the second electrode plate are stacked and wound into a wound structure.

[0022] In some embodiments, m is greater than 1, the m electrode units are arranged in a direction in which the electrode units are bent and extended when viewed along the second direction, and the n structural members are attached to and connected to the second walls of the m electrode units.

[0023] The arrangement of the electrode units allows the tabs between the multiple electrode units to be connected directly inside the packaging bag, which is beneficial to improving the energy density of the secondary battery.

[0024] In some embodiments, m is greater than 1, m electrode units are stacked along the first direction, and the second wall of each electrode unit is adhered to and connected to at least one structural member.

[0025] The arrangement of the electrode units allows the tabs between the multiple electrode units to be connected directly inside the packaging bag, which is beneficial to improving the energy density of the secondary battery.

[0026] In some embodiments, the material of the structural member is one or more of stainless steel, memory alloy, polymethyl methacrylate, and polypropylene.

[0027] The above-mentioned materials are helpful in improving the bending strength of the structural member, thereby helping the structural member to offset the force generated by the deformation tendency of the electrode unit.

[0028] In some embodiments, in the first direction, a projection of the structural member is located within a projection of the electrode assembly.

[0029] The projection of the above-mentioned structural member is located within the projection of the electrode assembly, so that there is additional space for accommodating the electrolyte in the packaging bag, thereby enhancing the cycle performance of the secondary battery.

[0030] In addition, the present application also provides an electronic device that can help improve reliability.

[0031] Some embodiments of the present application provide an electronic device, which includes a secondary battery as described in any of the above embodiments.

[0032] The secondary battery of the above-mentioned electronic device has improved the ability to suppress the deformation of the electrode unit, thereby reducing the deformation of the secondary battery, reducing the risk of lithium plating in the secondary battery and improving the processing efficiency of the secondary battery, which is beneficial to improving the reliability of the electronic device using the secondary battery and also improving the production efficiency of the electronic device.

[0033] The secondary battery of the present application includes an electrode assembly, a structural member and a packaging bag. The electrode assembly and the structural member are bent in a first direction, and the electrode unit of the electrode assembly includes a first wall and a second wall sequentially arranged in the first direction. The structural member is fixed to the electrode assembly, and the structural member is arranged on at least one of the first wall and the second wall. The packaging bag is used to accommodate the electrode assembly and the structural member. The bent structural member is attached to and connected to the electrode unit to offset at least part of the force generated by the deformation tendency of the electrode unit due to the reduction of the curvature and equalization, and the force generated by the deformation of the electrode unit is also transmitted to the structural member through the packaging bag. The structural member offsets at least part of the force transmitted from the packaging bag, thereby suppressing the deformation of the electrode unit, thereby reducing the risk of lithium plating in the electrode assembly and helping to reduce the reserved space of the battery compartment for accommodating the secondary battery. It is also conducive to the use of fixtures in the production process, thereby facilitating the production and installation of the secondary battery, and improving the reliability and applicability of the secondary battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] FIG1 is a schematic structural diagram of a secondary battery provided in one embodiment of the present application.

[0035] FIG. 2 is a schematic cross-sectional view of the secondary battery along the cutting line AA in FIG. 1 .

[0036] FIG3 is a schematic structural diagram of a secondary battery provided in one embodiment of the present application.

[0037] FIG4 is a schematic cross-sectional view of the secondary battery along the cutting line BB in FIG3 .

[0038] FIG5 is a schematic cross-sectional view of a secondary battery provided in one embodiment of the present application.

[0039] FIG6 is a schematic cross-sectional view of a secondary battery provided in one embodiment of the present application.

[0040] FIG7 is a schematic cross-sectional view of a secondary battery provided in one embodiment of the present application.

[0041] FIG8 is a top view of a secondary battery provided in accordance with an embodiment of the present application.

[0042] FIG9 is a schematic structural diagram of a secondary battery provided in a first comparison of the present application.

[0043] FIG10 is a schematic cross-sectional view of the secondary battery along the cutting line CC in FIG9 .

[0044] FIG11 is a schematic diagram of an electronic device provided in accordance with an embodiment of the present application.

[0045] Main Component Symbols Secondary battery 100 Electrode assembly 10 Electrode unit 11 First wall 111 Second wall 112 First electrode sheet 113 Second electrode sheet 114 Separator 115 Structural member 20 Packaging bag 30 Third wall 31 Fourth wall 32 First electrode tab 40 Second electrode tab 50 First adhesive layer 60 Second adhesive layer 70 Electronic device 1000 First direction X Second direction Y Third direction Z DETAILED DESCRIPTION

[0046] The technical solutions in the embodiments of the present application will be described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments.

[0047] It should be noted that when a component is considered to be "connected to" another component, it can be directly connected to the other component or there may be an intermediate component. When a component is considered to be "disposed on" another component, it can be directly disposed on the other component or there may be an intermediate component. The terms "top", "bottom", "upper", "lower", "left", "right", "front", "back", and similar expressions used herein are for illustrative purposes only.

[0048] The term "perpendicular" is used to describe the ideal state between two components. In actual production or use, there may be a state that is approximately perpendicular between the two components. For example, combined with numerical descriptions, perpendicular can refer to the angle between two straight lines being in the range of 90°±10°, perpendicular can also refer to the dihedral angle between two planes being in the range of 90°±10°, and perpendicular can also refer to the angle between a straight line and a plane being in the range of 90°±10°. The two components described as "perpendicular" may not be absolute straight lines or planes, but may be roughly straight lines or planes. From a macroscopic perspective, a component can be considered a "straight line" or a "plane" if the overall extension direction is a straight line or a plane.

[0049] It should be noted that when a parameter is greater than, equal to, or less than a certain endpoint value, it should be understood that the endpoint value is allowed to have a tolerance of ±10%. For example, if the ratio of A to B is greater than 10, it should be understood to include the case where the ratio of A to B is greater than 9, and also include the case where the ratio of A to B is greater than 11.

[0050] Unless otherwise specified, the term "plurality" as used herein means two or more than two.

[0051] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application pertains. The terms used herein in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application.

[0052] The present application discloses a secondary battery, comprising an electrode assembly, a structural member, and a packaging bag. The electrode assembly is bent in a first direction and includes m electrode units, where m is an integer greater than or equal to 1. The electrode units include a first wall and a second wall arranged sequentially in the first direction, both of which are bent in the first direction. The structural member is bent in the first direction and is fixed to the electrode assembly, and is disposed on at least one of the first wall and the second wall. The packaging bag is used to accommodate the electrode assembly and the structural member.

[0053] The above-mentioned curved structural parts are fitted and connected to the electrode unit to offset at least part of the force generated by the deformation trend of the electrode unit due to the reduction of curvature and equalization, and the force generated by the deformation of the electrode unit is also transmitted to the structural parts through the packaging bag. The structural parts offset at least part of the force transmitted from the packaging bag, thereby suppressing the deformation of the electrode unit, thereby reducing the risk of lithium plating in the electrode assembly and helping to reduce the reserved space of the battery compartment for accommodating secondary batteries. It is also conducive to the use of fixtures in the production process, thereby facilitating the production and installation of secondary batteries, and improving the reliability and applicability of secondary batteries.

[0054] The following will describe some embodiments of the present application in conjunction with the accompanying drawings. In the absence of conflict, the following embodiments and features in the embodiments may be combined with each other.

[0055] Referring to Figures 1 and 2, an embodiment of the present application provides a secondary battery 100, which includes an electrode assembly 10, a structural member 20, and a packaging bag 30. The electrode assembly 10 and the structural member 20 are both bent along a first direction X, the structural member 20 is adhered to and connected to the electrode assembly 10, and the packaging bag 30 is used to accommodate the electrode assembly 10 and the structural member 20.

[0056] 2 , the electrode assembly 10 includes an electrode unit 11 , which is bent along a first direction X. The first direction X is defined as the direction from the convex side of the bent electrode assembly 10 toward the concave side.

[0057] In some embodiments, referring to FIG. 1 to FIG. 4 , the electrode unit 11 includes a first electrode piece 113 , a second electrode piece 114 , and a diaphragm 115 disposed between the first electrode piece 113 and the second electrode piece 114 .

[0058] The first electrode 113 and the second electrode 114 have different polarities. For example, the first electrode 113 is a positive electrode and the second electrode 114 is a negative electrode. In another example, the first electrode 113 is a negative electrode and the second electrode 114 is a positive electrode. The first electrode 113 and the second electrode 114 are formed by combining an active material layer on a metal layer. For example, if the first electrode 113 is a positive electrode, a positive electrode slurry can be combined with at least one metal layer such as aluminum, platinum, nickel, tantalum, titanium, etc., and the positive electrode slurry combined with the metal layer forms a positive electrode active material layer. If the second electrode 114 is a negative electrode, a negative electrode slurry can be combined with at least one metal layer such as copper, platinum, nickel, tantalum, titanium, etc., and the negative electrode slurry combined with the metal layer forms a negative electrode active material layer. Of course, the metal layers used by the first pole piece 113 and the second pole piece 114 are different. For example, the first pole piece 113 uses an aluminum metal layer, and the second pole piece 114 uses a copper metal layer.

[0059] The diaphragm 115 can be made of materials such as PE (polyethylene) or PP (polypropylene), and is used to isolate the first electrode 113 from the second electrode 114 .

[0060] In some embodiments, see Figure 2 , the first electrode 113 , the diaphragm 115 , and the second electrode 114 are stacked into a laminate structure. In other embodiments, see Figure 4 , the first electrode 113 , the diaphragm 115 , and the second electrode 114 are stacked and wound into a wound structure.

[0061] In some embodiments, referring to FIG. 5 , m is greater than 1, and a plurality of electrode units 11 are stacked along a first direction X. When viewed along a second direction Y perpendicular to the first direction, each electrode unit 11 is a stacked laminate structure. The electrode units 11 may also be a wound structure with a central winding axis parallel to a third direction Z, and the third direction Z is perpendicular to both the first direction X and the second direction Y.

[0062] In some embodiments, referring to FIG. 6 , m is greater than 1, and when viewed along the second direction Y, the plurality of electrode units 11 are arranged along a direction in which the electrode units 11 are bent and extended.

[0063] In some embodiments, m is an integer greater than or equal to 3, and the plurality of electrode units 11 are stacked along the first direction X and arranged in a direction in which the electrode units 11 are bent and extended when viewed along the second direction Y.

[0064] In some embodiments, referring to Figures 1 and 2, the secondary battery 100 further includes a first electrode tab 40 and a second electrode tab 50. The first electrode tab 40 and the second electrode tab 50 are conductive metal components. The first electrode piece 113 of the electrode unit 11 is connected to the first electrode tab 40 so that the polarity of the first electrode tab 40 is the same as that of the first electrode piece 113. The second electrode piece 114 of the electrode unit 11 is connected to the second electrode tab 50 so that the polarity of the second electrode tab 50 is the same as that of the second electrode piece 114. The first electrode tab 40 and the second electrode tab 50 extend out of the packaging bag 30 to lead out the polarity of the electrode unit 11.

[0065] In some embodiments, each electrode unit 11 is connected to a first electrode tab 40 and a second electrode tab 50 , and each electrode unit 11 can be connected in series or in parallel via the first electrode tab 40 or the second electrode tab 50 , which is not specifically limited here.

[0066] In some embodiments, referring to Figures 1 and 2, the first pole tab 40 and the second pole tab 50 can both extend from one end of the secondary battery 100 along the third direction Z, or the first pole tab 40 can extend from one end of the secondary battery 100 along the third direction Z, and the second pole tab 50 can extend from the end of the secondary battery 100 along the third direction Z away from the first pole tab 40.

[0067] In other embodiments, the first electrode tab 40 and the second electrode tab 50 may also be projected from other ends of the secondary battery 100 , which is not specifically limited here.

[0068] 2 to 6 , each electrode unit 11 includes a first wall 111 and a second wall 112 sequentially arranged in the first direction X, and both the first wall 111 and the second wall 112 are bent toward the first direction X.

[0069] In some embodiments, the first wall 111 may be a portion of one of the first electrode 113 , the second electrode 114 or the diaphragm 115 , and the second wall 112 may be a portion of one of the first electrode 113 , the second electrode 114 or the diaphragm 115 .

[0070] Please refer to FIG. 2 to FIG. 6 . The structural member 20 is a solid component with a certain bending resistance. The structural member 20 is fixed to the electrode unit 11 .

[0071] In some embodiments, referring to Figures 2 to 6, with respect to the electrode unit 11 connected with the structural member 20, the structural member 20 is fixed to the second wall 112 of the electrode unit 11. The connection and combination of the curved structural member 20 and the second wall 112 of the electrode unit 11 can directly offset at least part of the force generated by the deformation tendency of the electrode unit 11, thereby suppressing the deformation of the electrode unit 11. Typically, the electronic device 1000 using the curved secondary battery 100 corresponds to a curved device such as a head-mounted VR device, a bracelet, a watch, etc. The concave surface of such an electronic device 1000 is usually facing the human body. The second wall 112 of the present application is a concave wall. When the structural member 20 is arranged on the second wall 112, a protective structure can be added between the electrode unit 11 and the human body, thereby reducing the risk of harm to the human body when the electrode unit 11 is damaged, and further improving the reliability of the secondary battery 100.

[0072] In some embodiments, please refer to Figure 7. For the electrode unit 11 connected to the structural member 20, the structural member 20 is fixed to the first wall 111 of the electrode unit 11. The curved structural member 20 and the first wall 111 of the electrode unit 11 are connected and combined to directly offset at least part of the force generated by the deformation tendency of the electrode unit 11, thereby suppressing the deformation of the electrode unit 11.

[0073] In some embodiments, for an electrode unit 11 connected to a structural member 20, the first wall 111 and the second wall 112 of the electrode unit 11 are both fixed with the structural member 20. The curved structural member 20 connected to the first wall 111 and the second wall 112 of the electrode unit 11 can directly offset at least part of the force generated by the deformation tendency of the electrode unit 11, thereby suppressing the deformation of the electrode unit 11. In addition, when the second wall 112 is connected to the structural member 20, a protective structure can be added between the electrode unit 11 and the human body, reducing the risk of injury to the human body if the electrode unit 11 is damaged, further improving the reliability of the secondary battery 100.

[0074] In some embodiments, referring to FIG. 5 and FIG. 6 , m is greater than 1, and the second wall 112 of each electrode unit 11 fixes the structural member 20 , which helps to suppress the deformation of each electrode unit 11 and further reduce the risk of deformation of the secondary battery 100 .

[0075] In some embodiments, referring to FIG. 2 and FIG. 4 , the secondary battery 100 further includes a first adhesive layer 60 , which bonds the structural member 20 to the electrode unit 11 of the electrode assembly 10 .

[0076] In some embodiments, referring to FIG. 2 and FIG. 4 , the first adhesive layer 60 is disposed between the structural member 20 and the second wall 112 of the electrode unit 11 , which is beneficial for further improving the tightness of the connection between the structural member 20 and the second wall 112 .

[0077] In the embodiment where the structural member 20 is fixed to the first wall 111 , the structural member 20 and the first wall 111 may also be bonded via the first adhesive layer 60 , and the first adhesive layer 60 may also be provided between the structural member 20 and the first wall 111 .

[0078] In some embodiments, the first adhesive layer 60 may be a structural adhesive that changes from a liquid state to a fixed state, or may be a single-sided or double-sided adhesive tape or strip, which is not specifically limited here.

[0079] In some embodiments, the material of the first adhesive layer 60 may include but is not limited to at least one of polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene oxide-containing polymers, polyvinyl pyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyacrylic acid, styrene-butadiene rubber, acrylic (ester) styrene-butadiene rubber, epoxy resin or nylon.

[0080] In other embodiments, the structural member 20 and the first wall 111 , and the structural member 20 and the second wall 112 may also be fixed by hot pressing, bundling, etc., which will not be described in detail here.

[0081] 5 and 6 , in the first direction X, the projection of the structural member 20 is located within the projection of the electrode assembly 10 , so that the packaging bag 30 has additional space for accommodating the electrolyte, thereby enhancing the cycle performance of the secondary battery 100 .

[0082] In some embodiments, referring to FIG5 , m is greater than 1, a plurality of electrode units 11 are stacked along a first direction X, and the second wall 112 of each electrode unit 11 is adhered to and connected with at least one structural member 20. The second wall 112 of each electrode unit 11 is adhered to and connected with at least one structural member 20 so that a structural member 20 is provided between two adjacent electrode units 11, thereby improving the uniformity of the distribution of the structural member 20 and further enhancing the ability of the structural member 20 to suppress the deformation of the electrode assembly 10.

[0083] In some embodiments, a plurality of structural members 20 are attached to and connected to the second wall 112 of each electrode unit 11 . The plurality of structural members 20 are stacked along the first direction X, and any two adjacent structural members 20 are attached to and connected to each other.

[0084] In some embodiments, the second wall 112 of each electrode unit 11 is attached to and connected with a plurality of structural members 20 , and the plurality of structural members 20 are arranged in a direction in which the structural members 20 bend and extend when viewed along the second direction Y.

[0085] In some embodiments, referring to FIG. 6 , m is greater than 1, and the plurality of electrode units 11 are arranged in a direction in which the electrode units 11 are bent and extended when viewed along the second direction Y. The number of structural members 20 is n, where n is an integer greater than or equal to 1, and the n structural members 20 are adhered to and connected to the second walls 112 of the plurality of electrode units 11.

[0086] In some embodiments, n is greater than 1, and any two adjacent structural members 20 are attached and connected. When multiple electrode units 11 form an electrode assembly 10 with a relatively large curvature, by providing multiple structural members 20, the curvature of each individual structural member 20 does not need to be set too large, thereby reducing the problem of difficult processing due to the required curvature of the structural member 20.

[0087] In some embodiments, m is greater than 1, and the first walls 111 of a portion of the electrode units 11 are attached to and connected to the structural member 20, the second walls 112 of a portion of the electrode units 11 are attached to and connected to the structural member 20, and a portion of the electrode units 11 are not connected to the structural member 20. Of course, other combinations are possible, which will not be detailed here.

[0088] In some embodiments, referring to FIG. 2 and FIG. 8 , n is greater than or equal to 1, and the width of the nth structural member 20 in the second direction Y is B. n When viewed along the second direction Y, the length of the n-th structural member 20 bent and extended is L n The third direction Z is perpendicular to the first direction X and the second direction Y. The electrode assembly 10 has a first width T along the second direction Y and a first length P of the electrode assembly 10 when it is bent and extended when viewed along the second direction Y, satisfying B n ≤T, and L n≤P.

[0089] The length L of the nth structural member 20 bent and extended when the structural member 20 is viewed along the second direction Y is n It can be regarded as the length of the structural member 20 along the third direction Z before being bent or flattened, and the first length P can be regarded as the length of the electrode assembly 10 along the third direction Z before being bent or flattened.

[0090] It should be noted that setting the width of the structural member 20 in the second direction Y to be smaller than the width of the electrode assembly 10 in the second direction Y, and setting the length of the structural member 20 along the bending direction of the structural member 20 when viewed along the second direction Y to be smaller than the bending length of the electrode assembly 10 along the electrode assembly 10 when viewed in the second direction Y, is beneficial to reducing the space occupied by the structural member 20, and can ensure that the structural member 20 does not exceed the electrode assembly 10 in the second direction Y and in the bending direction of the electrode assembly 10 when viewed along the second direction Y, which is beneficial to ensure that the structural member 20 does not occupy the space of the secondary battery 100 in the second direction Y and in the bending direction of the electrode assembly 10 when viewed along the second direction Y.

[0091] In some embodiments, 2 / 3×T≤B n ≤T, and 2 / 3×P≤L n ≤P. By setting 2 / 3×T≤B n and 2 / 3×P≤L n , when a structural member 20 is connected to an electrode unit 11, the area available for bonding and connection between the electrode unit 11 and the structural member 20 is increased, thereby reducing the risk of connection problems such as reduced connection area, detachment, and other poor connection between the structural member 20 and the electrode unit 11. Furthermore, increasing the length and width of the structural member 20 helps improve the structural member 20's ability to suppress deformation of the electrode unit 11.

[0092] In some embodiments, the thickness of the geometric center portion of the structural member 20 along the first direction X is greater than the thickness of the edge portion of the structural member 20 along the first direction X. When the length and width of the structural member 20 are smaller than the electrode assembly 10, the structural member 20 will lift the packaging bag 30. The reduced thickness of the edge portion of the structural member 20 along the first direction X helps to reduce the height of the packaging bag 30 at the edge of the structural member 20 when it is lifted up, thereby reducing the stress on the packaging belt at the edge of the structural member 20, thereby reducing the risk of damage to the packaging bag 30.

[0093] In some embodiments, the structural member 20 is a plate member with curved edges, which helps reduce the stress on the packaging strap at the edge of the structural member 20, thereby reducing the risk of damage to the packaging bag 30. Specific processing methods include chamfering the edges of the plate-shaped structural member 20, or directly cutting the structural member 20 into a circular plate.

[0094] In some embodiments, the structural member 20 and the electrode unit 11 are adhesively connected. For example, when the structural member 20 is connected to the first wall 111, glue is provided between the structural member 20 and the first wall 111 to achieve an adhesive connection between the structural member 20 and the first wall 111; for another example, when the structural member 20 is connected to the second wall 112, glue is provided between the structural member 20 and the second wall 112 to achieve an adhesive connection between the structural member 20 and the second wall 112.

[0095] In some other embodiments, the structural member 20 and the electrode unit 11 are connected by heat pressing.

[0096] In some embodiments, the material of the structural member 20 can be one or more of stainless steel, memory alloy, polymethyl methacrylate, and polypropylene. For example, the structural member 20 is a stainless steel plate, an aluminum alloy plate, or a plastic plate.

[0097] In some embodiments, the structural member 20 is a stainless steel plate, which has the advantage of being resistant to corrosion by electrolyte.

[0098] The packaging bag 30 is a soft packaging bag 30, which is used to accommodate and encapsulate the electrode assembly 10 and the structural member 20. The force generated by the deformation trend of the electrode unit 11 such as the reduction of curvature and equalization can be transmitted to the structural member 20 through the packaging bag 30. The structural member 20 offsets at least part of the force generated by the electrode unit 11, thereby suppressing the deformation of the electrode unit 11.

[0099] During the charge and discharge process of the secondary battery 100, the electrode unit 11 will tend to deform with its curvature reduced and become equal. This may cause misalignment between the first electrode piece 113 and the second electrode piece 114, leading to lithium deposition at the interface, weakened cycle performance, and ultimately reduced reliability of the secondary battery 100. In addition, the deformation of the electrode unit 11 may also cause the secondary battery 100 and the battery compartment used to accommodate the battery to squeeze each other, requiring a larger installation space to be reserved for the battery compartment, which is not conducive to the installation of the secondary battery 100. The deformation produced by different individual secondary batteries 100 may be different, and it is difficult to adapt the fixture for the secondary battery 100 during the production process, which is not conducive to the smooth progress of the production process, thereby reducing the production efficiency of the secondary battery 100.

[0100] The structural member 20 of the present application is attached to and connected to at least one of the first wall 111 and the second wall 112, so that the force generated by the deformation tendency of the bent electrode unit 11 can be directly transmitted to the structural member 20, and the structural member 20 offsets at least part of the force transmitted by the electrode unit 11, and the structural member 20 is arranged in the packaging bag 30, so that the force generated by the deformation tendency of the bent electrode unit 11 can be transmitted to the structural member 20 through the packaging bag 30, and the structural member 20 offsets at least part of the force transmitted from the packaging bag 30, thereby further offsetting the force generated by the deformation tendency of the electrode unit 11. The combination of the above two is conducive to the structural member 20 suppressing the deformation of the electrode unit 11, reducing the risk of interface lithium deposition and weakened cycle performance due to misalignment between the first electrode piece 113 and the second electrode piece 114, thereby improving the reliability of the secondary battery 100. Suppressing the deformation of the electrode unit 11 can further suppress the deformation of the secondary battery 100. By suppressing the deformation of the secondary battery 100, the reserved space in the battery compartment outside of the secondary battery 100 can be reduced, thereby improving space utilization, reducing the risk of damage to the secondary battery 100 due to mutual force between the secondary battery 100 and the battery compartment due to deformation, and facilitating the installation of the secondary battery 100. Suppressing the deformation of the secondary battery 100 can also be applied to fixtures used in the production process, facilitating the smooth progress of the production process and thereby improving the production efficiency of the secondary battery 100.

[0101] Furthermore, if the structural member 20 is disposed outside the packaging bag 30 so that the structural member 20 is attached to and connected to the packaging bag 30, then if a poor connection occurs between the structural member 20 and the packaging bag 30, such as a reduction in the connection area or detachment, the structural member 20 will have difficulty in suppressing deformation of the electrode unit 11. The present application disposes the structural member 20 inside the packaging bag 30, where the packaging bag 30 acts as a restraint, thereby alleviating the burden on the connection between the electrode unit 11 and the structural member 20 when the electrode unit 11 directly transmits force to the structural member 20, reducing the risk of poor connection of the structural member 20, and still suppressing deformation of the electrode unit 11 even when the structural member 20 is poorly connected.

[0102] In some embodiments, referring to Figures 2 to 7, the packaging bag 30 includes a third wall 31 and a fourth wall 32 arranged in sequence in the first direction X, the third wall 31 is adjacent to the first wall 111 compared to the fourth wall 32, and the fourth wall 32 is adjacent to the second wall compared to the third wall 31.

[0103] In some embodiments, referring to Figures 2-4 , the third wall 31 is at least partially aligned with the first wall 111, placing the third and fourth walls 31, 32 of the packaging bag 30 in direct contact with the electrode unit 11 and the structural member 20. This facilitates direct transmission of the force generated by the deformation tendency of the electrode unit 11 to the structural member 20 via the packaging bag 30, thereby facilitating the structural member 20 to offset the force generated by the electrode unit 11 and thereby enhancing the effectiveness of the structural member 20 in suppressing deformation of the electrode unit 11. The secondary battery 100 further includes a second adhesive layer 70, which bonds the fourth wall 32 to the structural member 20. This improves the tightness of the bond between the fourth wall 32 and the structural member 20, enhances drop resistance, and reduces movement and friction between the structural member 20 and the packaging bag 30.

[0104] In some embodiments, referring to FIG. 2 to FIG. 4 , the second adhesive layer 70 is disposed between the structural member 20 and the fourth wall 32 , which helps to further improve the tightness of the connection between the structural member 20 and the fourth wall 32 .

[0105] In the embodiment where the structural member 20 is fixed to the first wall 111 , the second adhesive layer 70 bonds the third wall 31 and the structural member 20 . The second adhesive layer 70 may also be disposed between the third wall 31 and the structural member 20 .

[0106] In some embodiments, the second adhesive layer 70 may be a structural adhesive that changes from a liquid state to a fixed state, or may be a single-sided or double-sided adhesive tape or strip, which is not specifically limited here.

[0107] In some embodiments, the second adhesive layer 70 may be made of at least one of a material including but not limited to polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene oxide-containing polymers, polyvinyl pyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyacrylic acid, styrene-butadiene rubber, acrylic (ester) styrene-butadiene rubber, epoxy resin or nylon.

[0108] In some embodiments, referring to FIG. 5 , m is an integer greater than 1, and a plurality of electrode units 11 are stacked along a first direction X. Along the first direction X, a structural member 20 is provided between the second wall 112 of the electrode unit 11 and the packaging bag 30, and the structural member 20 is in direct contact with both the second wall 112 and the packaging bag 30, thereby facilitating the packaging bag 30 to transmit the force generated by the deformation tendency of the electrode unit 11 to the structural member 20, thereby facilitating improving the effect of the packaging bag 30 in suppressing the deformation of the electrode unit 11.

[0109] In some embodiments, the packaging bag 30 is made of a composite of multiple materials. For example, the third wall 31 is made of aluminum-plastic film, and the fourth wall 32 is made of steel-plastic film. Steel-plastic film has a greater bending strength than aluminum-plastic film. Since the fourth wall 32, which is in contact with the structural member 20, is made of steel-plastic film, when the force generated by the deformation tendency of the electrode unit 11 is transmitted to the third wall 31 made of aluminum-plastic film, the third wall 31 transmits the force to the fourth wall 32 made of steel-plastic film. The fourth wall 32 made of steel-plastic film has a greater bending strength than the third wall 31 made of aluminum-plastic film, which can offset at least part of the force transmitted by the third wall 31. This allows the fourth wall 32 to suppress deformation of the electrode unit 11, thereby facilitating a reduction in the thickness of the structural member 20 in the first direction X and improving the energy density of the secondary battery 100.

[0110] In some embodiments, the fourth wall 32 is a steel-plastic film. The fourth wall 32 is connected to the structural member 20, which can improve the integrity of the steel-plastic film and the structural member 20 and further inhibit deformation of the electrode unit 11. The fourth wall 32 and the structural member 20 can be connected by bonding or hot pressing, which is not specifically limited here.

[0111] In some other embodiments, the packaging bag 30 is made of a uniform material, such as aluminum-plastic film or steel-plastic film.

[0112] In some embodiments, the electrode assembly 10 includes an electrode unit 11 and a structural member 20. When the structural member 20 is made of 304 stainless steel plate, the structural member 20 and the electrode unit 11 satisfy the following formula 1, which can make the arc radius change rate of the electrode unit 11 less than 4%.

[0113] Formula 1

[0114] Wherein, B represents the width of the structural member 20 in the second direction Y, L represents the length of the structural member 20 bent and extended when viewed along the second direction Y, and H represents the thickness of the structural member 20 in the first direction X. W represents the width of the electrode unit 11 in the second direction Y, C represents the length of the electrode unit 11 bent and extended when viewed along the second direction Y, and D represents the thickness of the electrode unit 11 in the first direction X.

[0115] When the rate of change of the radian radius of the electrode unit 11 is too large, there is a risk of misalignment between the first electrode piece 113 and the second electrode piece 114, resulting in lithium deposition at the interface, which in turn leads to a weakening of the cycle performance and a reduction in the reliability of the secondary battery 100. In addition, the deformation of the electrode unit 11 may also cause the secondary battery 100 and the battery compartment for accommodating the battery to squeeze each other, which is not conducive to the installation of the secondary battery 100. The deformation produced by different individual secondary batteries 100 may be different, which makes it difficult to adapt the fixture for the secondary battery 100, which is not conducive to the smooth progress of the production process, thereby reducing the production efficiency of the secondary battery 100. The present application reduces the risk of the above-mentioned problems by controlling the rate of change of the radian radius of the electrode unit to be less than 4%.

[0116] The process of the secondary battery 100 in the embodiment of the present application being discharged from a fully charged state to a fully discharged state and then charged to a fully charged state is called one cycle.

[0117] The cycle test of the embodiment of the present application is as follows: in an environment of 45° C., the secondary battery 100 is charged and discharged in a cycle from a fully discharged state to a fully charged state, and a total of 400 cycles are completed.

[0118] The test method of the arc radius change rate of the electrode unit 11 in the embodiment of the present application is as follows:

[0119] To obtain an initial arc radius, when the secondary battery 100 is not subjected to a cycle test, a 3D profilometer is used to scan the 3D structure of the surface of the secondary battery 100 . The scanned surface is then averaged to obtain an arc line. Three points on the arc line are fitted to obtain a standard circular arc line, and then the arc radius a is read.

[0120] To obtain the post-cycle arc radius, after the secondary battery 100 completes the cycle test, a 3D profilometer is used to scan the 3D structure of the surface of the secondary battery 100 . The scanned surface is then averaged to obtain an arc line. Three points are fitted on the arc line to obtain a standard circular arc line, and then the arc radius b is read.

[0121] The arc radius change rate is obtained. The arc radius change rate of the electrode unit 11 is (ba) / a.

[0122] The principle of point selection is as follows: the arc obtained by point fitting should coincide with the arc obtained by surface averaging as much as possible and points near the endpoints should be excluded.

[0123] In some embodiments, the electrode assembly unit includes one or more electrode units 11, and the structural member 20 is one or more. The material of each structural member 20 may be different. The bending strength of 304 stainless steel is 40 MPa. The structural member 20 and the electrode unit 11 satisfy the following formula 2, which can make the curvature radius change rate of the electrode unit 11 less than 4%.

[0124] Formula 2

[0125] Among them, B n represents the width of the nth structural member 20 in the second direction Y, L n H represents the length of the nth structural member 20 when viewed along the second direction Y. n W represents the thickness of the n-th structural member 20 in the first direction X. m represents the width of the mth electrode unit 11 in the second direction Y perpendicular to the first direction X, Cm represents the length of the mth electrode unit 11 bent and extended when viewed along the second direction Y, and Dm represents the thickness of the mth electrode unit 11 in the first direction X. n It represents the bending strength of the n-th structural member 20.

[0126] The bending strength of the structural member 20 is calculated as follows: Take a specimen for calculation. The specimen is the structural member 20. The specimen has a length of l, a width of b, and a thickness of h. The specimen is placed symmetrically on two supports with a distance K between the two supports. A force is applied to the specimen along the thickness direction at the center of the line connecting the two supports at a rate of 0.5 mm / min until the specimen breaks. The load value F at the time of fracture is read. The bending strength of the specimen is calculated according to the following formula: σ = 3FK / (2b×h 2 ).

[0127] In order to verify the effect of the structural member 20 on suppressing the deformation of the electrode unit 11 when the structural member 20 is disposed inside the packaging bag 30, the following comparative test was conducted compared with the effect of the structural member 20 on suppressing the deformation of the electrode unit 11 when the structural member 20 is disposed outside the packaging bag 30:

[0128] Example 1

[0129] In this embodiment, the first electrode 113 is a positive electrode, and the second electrode 114 is a negative electrode. The first electrode 113 and the second electrode 114 are both prepared by disposing an active material layer on a current collector.

[0130] (Preparation of First Pole Plate 113)

[0131] Lithium cobalt oxide, polyvinylidene fluoride (PVDF), and conductive carbon black (SP) were mixed in a mass ratio of 97:1.5:1.5, and NMP was added as a solvent to form a slurry with a solid content of 75 wt%, which was then stirred evenly. The slurry was evenly coated on one surface of a 6 mm thick positive electrode current collector aluminum foil through a coating process and dried at 85°C to obtain a positive electrode sheet with a positive electrode active material layer thickness of 120 μm. The above steps were then repeated on the other surface of the positive electrode sheet to obtain a negative electrode sheet coated with positive electrode active material on both sides. The obtained positive electrode sheet was then cold pressed, slit, cut, and the tabs were welded to obtain the first electrode sheet 113.

[0132] (Preparation of Second Pole Plate 114)

[0133] Artificial graphite, conductive carbon black (SP), styrene-butadiene rubber (SBR), and sodium carboxymethyl cellulose (CMC) were mixed in a mass ratio of 97:1:1:1, and deionized water was added to form a slurry with a solid content of 75 wt%. The mixture was then stirred evenly. The slurry was evenly coated on one surface of a 6 mm thick negative electrode current collector copper foil and dried at 85°C to obtain a negative electrode sheet with a negative electrode active material layer thickness of 120 μm. The above steps were then repeated on the other surface of the negative electrode sheet to obtain a negative electrode sheet coated with negative electrode active material on both sides. The resulting negative electrode sheet was then cold pressed, slit, cut, and the tabs were welded to obtain a second electrode sheet 114.

[0134] (Preparation of Electrolyte)

[0135] Ethylene carbonate, propylene carbonate, diethyl carbonate, propyl propionate and vinylene carbonate are mixed in a mass ratio of 20:30:20:28:2 to obtain a non-aqueous organic solvent. Then, lithium salt LiPF6 and the non-aqueous organic solvent are prepared in a mass ratio of 8:92 to obtain an electrolyte.

[0136] (Preparation of Separator 115)

[0137] A porous polyethylene film with a thickness of 7 μm was used.

[0138] (Preparation of Structural Member 20)

[0139] The 304 stainless steel plate is bent in the first direction X. The bent and extended length L1 of the structural member 20 when viewed in the second direction Y is 48 mm. The width B1 of the structural member 20 in the second direction Y is 51 mm. The thickness H1 of the structural member 20 in the first direction X is 0.15 mm.

[0140] (Preparation of Secondary Battery 100)

[0141] The first electrode sheet 113, separator 115, and second electrode sheet 114 prepared above are stacked in sequence, with separator 115 positioned between the first electrode sheet 113 and the second electrode sheet 114 to provide isolation. The electrode unit 11 can be obtained by stacking the first electrode sheet 113, separator 115, and second electrode sheet 114 in this order. Alternatively, the electrode unit 11 can be obtained by winding the stacked first electrode sheet 113, separator 115, and second electrode sheet 114. Refer to FIG. 2 , where there is one electrode unit 11, and one electrode unit 11 constitutes the electrode assembly 10. A force is applied to the electrode unit 11 until the electrode unit 11 bends in the first direction. When viewed along the second direction Y, the length C1 of the bent and extended electrode unit 11 is 53 mm (when there is one electrode unit 11, C1 equals P), the width W1 of the electrode unit 11 along the second direction Y is 56 mm (when there is one electrode unit 11, W1 equals T), and the thickness D1 of the electrode unit 11 along the first direction X is 8 mm. The number of structural members 20 is one, and the structural member 20 is attached to and connected to the second wall 112 of the electrode unit 11. The electrode unit 11 and the structural member 20 are placed in an aluminum-plastic film packaging bag 30, dried, and then injected with electrolyte. After vacuum packaging, standing, formation, degassing, and trimming, the secondary battery 100 is obtained.

[0142] In this embodiment, the structural member 20 is located in the packaging bag, and the electrode unit 11 and the structural member 20 satisfy the formula 1 and the condition: 2 / 3×T≤B n ≤T and 2 / 3×P≤L n ≤P. A cycle test is performed on the secondary battery 100. After the cycle test is completed, the change rate of the arc radius of the electrode unit 11 is 3%.

[0143] Example 2

[0144] Compared with Example 1, except for the difference in (preparation of the structural member 20 ), the rest is the same as Example 1.

[0145] (Preparation of Structural Member 20)

[0146] The 304 stainless steel plate is bent in the first direction X. The bent and extended length L1 of the structural member 20 when viewed in the second direction Y is 48 mm. The width B1 of the structural member 20 in the second direction Y is 36 mm. The thickness H1 of the structural member 20 in the first direction X is 0.15 mm.

[0147] In this embodiment, the structural member 20 is located in the packaging bag, and the electrode unit 11 and the structural member 20 satisfy the formula 1, but do not satisfy the condition: 2 / 3×T≤B n ≤T and 2 / 3×P≤L n≤P. A cycle test was performed on the secondary battery 100. After the cycle test was completed, the rate of change of the arc radius of the electrode unit 11 was 3.5%.

[0148] Comparative Example 1

[0149] Compared with Example 1, except for the difference in (preparation of the secondary battery 100 ), the rest is the same as Example 1.

[0150] (Preparation of Secondary Battery 100)

[0151] The first electrode sheet 113, separator 115, and second electrode sheet 114 prepared above are stacked in sequence, with separator 115 positioned between the first electrode sheet 113 and the second electrode sheet 114 to provide isolation. The first electrode sheet 113, separator 115, and second electrode sheet 114 are stacked sequentially to form an electrode unit 11. Alternatively, the stacked first electrode sheet 113, separator 115, and second electrode sheet 114 can be wound to form the electrode unit 11. Referring to Figures 9 and 10, there is one electrode unit 11, and one electrode unit 11 constitutes the electrode assembly 10. A force is applied to the electrode unit 11 until the electrode unit 11 bends in the first direction X. The length C1 of the bent extension of the electrode unit 11 when viewed along the second direction Y is 53 mm (when there is only one electrode unit 11, C1 equals P), the width W1 of the electrode unit 11 along the second direction Y is 56 mm (when there is only one electrode unit 11, W1 equals T), and the thickness D1 of the electrode unit 11 along the first direction X is 8 mm. The electrode unit 11 is placed in an aluminum-plastic film packaging bag 30, dried, and then injected with electrolyte. After vacuum packaging, standing, forming, degassing, and trimming, the number of structural members 20 is one. The structural member 20 is attached and connected to the side of the packaging bag 30 facing away from the second wall 112, thereby obtaining the secondary battery 100.

[0152] In this comparative example, the structural member 20 is located outside the packaging bag 30, and the electrode unit 11 and the structural member 20 satisfy the formula 1 and the condition: 2 / 3×T≤B n ≤T and 2 / 3×P≤L n ≤P. A cycle test is performed on the secondary battery 100. After the cycle test is completed, the change rate of the arc radius of the electrode unit 11 is 7%.

[0153] Comparative Example 2

[0154] Compared with Example 1, except for the difference in (preparation of the structural member 20 ), the rest is the same as Example 1.

[0155] (Preparation of Structural Member 20)

[0156] The 304 stainless steel plate is bent in the first direction X. The bent and extended length L1 of the structural member 20 when viewed in the second direction Y is 48 mm. The width B1 of the structural member 20 in the second direction Y is 35 mm. The thickness H1 of the structural member 20 in the first direction X is 0.05 mm.

[0157] In this comparative example, the structural member 20 is located in the packaging bag 30, and the electrode unit 11 and the structural member 20 do not satisfy the formula 1 and the condition: 2 / 3×T≤B n ≤T and 2 / 3×P≤L n ≤P. A cycle test is performed on the secondary battery 100. After the cycle test is completed, the change rate of the arc radius of the electrode unit 11 is 6%.

[0158] Comparative Example 3

[0159] Compared with Example 1, except for the differences in (preparation of the structural member 20 ) and (preparation of the secondary battery 100 ), the rest are the same as Example 1.

[0160] (Preparation of Structural Member 20)

[0161] The 304 stainless steel plate is bent in the first direction X. The bent and extended length L1 of the structural member 20 when viewed in the second direction Y is 48 mm. The width B1 of the structural member 20 in the second direction Y is 35 mm. The thickness H1 of the structural member 20 in the first direction X is 0.05 mm.

[0162] (Preparation of Secondary Battery 100)

[0163] The first electrode sheet 113, separator 115, and second electrode sheet 114 prepared above are stacked in order, with separator 115 positioned between the first electrode sheet 113 and the second electrode sheet 114 to provide isolation. The first electrode sheet 113, separator 115, and second electrode sheet 114 are stacked in order to form an electrode unit 11. Alternatively, the stacked first electrode sheet 113, separator 115, and second electrode sheet 114 can be wound to form the electrode unit 11. Referring to Figures 9 and 10, there is one electrode unit 11, and one electrode unit 11 constitutes the electrode assembly 10. A force is applied to the electrode unit 11 until the electrode unit 11 bends in the first direction X. The length C1 of the bent extension of the electrode unit 11 when viewed along the second direction Y is 53 mm (when there is only one electrode unit 11, C1 equals P). The width W1 of the electrode unit 11 along the second direction Y is 56 mm (when there is only one electrode unit 11, W1 equals T). The thickness D1 of the electrode unit 11 along the first direction X is 8 mm. The electrode unit 11 is placed in an aluminum-plastic film packaging bag 30, dried, and then injected with electrolyte. The bag undergoes vacuum packaging, resting, chemical formation, degassing, and trimming. There is only one structural member 20, which is attached and connected to the side of the packaging bag 30 facing away from the second wall 112 to obtain the secondary battery 100.

[0164] In this comparative example, the structural member 20 is located outside the packaging bag 30, and the electrode unit 11 and the structural member 20 do not satisfy the formula 1 and the condition: 2 / 3×T≤B n ≤T and 2 / 3×P≤L n ≤P. A cycle test is performed on the secondary battery 100. After the cycle test is completed, the change rate of the arc radius of the electrode unit 11 is 9%.

[0165] Referring to FIG. 11 , an embodiment of the present application further provides an electronic device 1000 comprising the secondary battery 100 of any of the aforementioned embodiments. Because the electronic device 1000 employs the technical solution of any of the aforementioned embodiments of the secondary battery 100, it at least exhibits the beneficial effects of the technical solution of any of the aforementioned embodiments of the secondary battery 100, which will not be further detailed here.

[0166] It should be noted that the secondary battery 100 of the electronic device 1000 has improved the ability to suppress the deformation of the electrode unit 11, thereby reducing the deformation of the secondary battery 100, reducing the risk of lithium plating in the secondary battery 100, and improving the processing efficiency of the secondary battery 100, which is beneficial to improving the reliability of the electronic device 1000 using the secondary battery 100 and also improving the production efficiency of the electronic device 1000.

[0167] Among them, the electronic device 1000 can be a VR head-mounted device, an AR head-mounted device, a smart watch, a smart bracelet or a curved screen, etc., which are not listed one by one here.

[0168] In addition, those skilled in the art should recognize that the above embodiments are merely intended to illustrate the present application and are not intended to limit the present application. As long as they are within the spirit of the present application, appropriate changes and modifications to the above embodiments are within the scope disclosed in the present application.

Claims

1. A secondary battery, characterized in that: The secondary battery comprises: An electrode assembly, wherein the electrode assembly is bent toward a first direction, the electrode assembly comprises m electrode units, where m is an integer greater than or equal to 1, and the electrode unit comprises a first wall and a second wall sequentially arranged in the first direction, and both the first wall and the second wall are bent toward the first direction; a structural member, the structural member is bent toward the first direction, the structural member is fixed to the electrode assembly, the structural member is arranged on at least one of the first wall and the second wall, the number of the structural members is n, and n is an integer greater than or equal to 1; A packaging bag, wherein the packaging bag is used to contain the electrode assembly and the structural member; The electrode assembly and the structural member satisfy the following formula: in, W m represents the width of the mth electrode unit in a second direction perpendicular to the first direction, Cm represents the length of the mth electrode unit bent and extended when viewed along the second direction, and Dm represents the thickness of the mth electrode unit in the first direction; B n represents the width of the nth structural member in the second direction, L n represents the length of the nth structural member bent and extended when viewed along the second direction, H n represents the thickness of the nth structural member in the first direction; σ n Represents: the bending strength of the nth structural member.

2. The secondary battery according to claim 1, characterized in that The electrode assembly has a first width T along the second direction, a first length P of the electrode assembly bent and extended when viewed along the second direction, 2 / 3×T≤B n ≤T and 2 / 3×P≤L n ≤P.

3. The secondary battery according to claim 1, characterized in that: The secondary battery further includes a first adhesive layer, and the structural member is fixed to the electrode assembly through the first adhesive layer.

4. The secondary battery according to claim 1, characterized in that: m=1, n=1, the structural member is disposed on the second wall of the electrode unit.

5. The secondary battery according to claim 4, characterized in that: The secondary battery further includes a second adhesive layer; the packaging bag includes a third wall and a fourth wall sequentially arranged in the first direction, the third wall is at least partially attached to the first wall, and the fourth wall is bonded to the structural member through the second adhesive layer.

6. The secondary battery according to claim 1, characterized in that: The packaging bag is made of at least one of aluminum-plastic film and steel-plastic film.

7. The secondary battery according to claim 6, characterized in that: The packaging bag comprises a third wall and a fourth wall sequentially arranged in the first direction, the third wall and the fourth wall are both bent toward the first direction, the third wall is made of aluminum-plastic film, and the fourth wall is made of steel-plastic film.

8. The secondary battery according to claim 1, characterized in that: The electrode unit includes a first pole piece, a second pole piece and a diaphragm arranged between the first pole piece and the second pole piece, and the first pole piece, the diaphragm and the second pole piece are stacked to form a stacked structure; or the first pole piece, the diaphragm and the second pole piece are stacked and wound into a wound structure.

9. The secondary battery according to claim 1, characterized in that: m is greater than 1, the m electrode units are arranged along a direction in which the electrode units are bent and extended, and the n structural members are disposed on the second walls of the m electrode units.

10. The secondary battery according to claim 1, characterized in that: m is greater than 1, m electrode units are stacked along the first direction, and the second wall of each electrode unit is provided with at least one structural member.

11. The secondary battery according to claim 1, characterized in that: The material of the structural member is one or more of stainless steel, memory alloy, polymethyl methacrylate, and polypropylene.

12. The secondary battery according to claim 1, characterized in that: In the first direction, the projection of the structural member is located within the projection of the electrode assembly.

13. An electronic device, characterized in that: The invention comprises the secondary battery according to any one of claims 1 to 12.

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