Secondary battery and electric device

Abstract

The invention discloses a secondary battery and electric equipment, the secondary battery comprises a shell, an electrode assembly, a plurality of first buffer parts and a plurality of second buffer parts, the electrode assembly is arranged in the shell, the first buffer parts are arranged on the inner wall of the shell, and the second buffer parts are arranged on the surface, facing the first buffer parts, of the electrode assembly. A first gap is formed between the electrode assembly and the shell in the first direction, the first buffer piece and the second buffer piece are located in the first gap, and the first direction is the thickness direction of the electrode assembly. The projection of the first buffer piece and the projection of the second buffer piece are at least partially overlapped in the direction perpendicular to the first direction. Observed in the first direction, at least part of the first buffer piece and the second buffer piece are arranged in a staggered mode, and the gap between at least part of the adjacent first buffer piece and second buffer piece is smaller than the gap between the electrode assembly and the shell. The possibility that the shell is impacted by the electrode assembly is reduced through the first buffer piece and the second buffer piece, and the service life of the secondary battery is prolonged.

Description

Technical Field

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

[0002] With the development of various electronic devices, secondary batteries have become an indispensable part of daily life. For example, commonly used mobile phones, tablets, laptops and digital cameras all require secondary batteries to provide power for normal operation. However, secondary batteries are inevitably dropped or vibrated during daily use, and the risk of secondary battery failure is high. Summary of the invention

[0003] For the secondary battery in the prior art, the inventor found that part of the reason for the failure of the secondary battery is that the electrode assembly is generally fixed in the receiving cavity by an adhesive, and the drop energy or vibration energy will be transmitted to the electrode assembly through the adhesive. In this way, when the secondary battery is dropped or vibrated with a large intensity, the electrode assembly is easy to impact the shell under the action of the drop energy or vibration energy, thereby causing the secondary battery to leak and fail.

[0004] In view of the above situation, it is necessary to provide a secondary battery that can reduce the possibility of the electrode assembly impacting the outer shell, thereby facilitating the improvement of the service life of the secondary battery.

[0005] In a first aspect, the present application provides a secondary battery, comprising a housing, an electrode assembly, a plurality of first buffers and a plurality of second buffers, wherein the housing has a receiving cavity, the electrode assembly is arranged in the receiving cavity, the first buffer is arranged on the inner wall of the housing, and the second buffer is arranged on the surface of the electrode assembly facing the first buffer. Along a first direction, there is a first gap between the electrode assembly and the housing, the first buffer and the second buffer are located in the first gap, and the first direction is the thickness direction of the electrode assembly. Along a direction perpendicular to the first direction, the projection of the first buffer and the projection of the second buffer overlap at least partially. When viewed along the first direction, at least some of the first buffers and the second buffers are arranged in an interlaced manner, and the gap between at least some of the adjacent first buffers and the second buffers is smaller than the gap between the electrode assembly and the housing. The gap between at least some of the adjacent first buffers and the second buffers is smaller than the gap between the electrode assembly and the housing, which means that at least some of the gaps between all the gaps between the first buffers and the second buffers that are adjacent to each other are smaller than the gap between the electrode assembly and the housing. At least part of the first buffer components and the second buffer components are staggered in arrangement, which means that some (greater than or equal to one) or all of the first buffer components are staggered in arrangement with the second buffer components, and / or some (greater than or equal to one) or all of the second buffer components are staggered in arrangement with the first buffer components.

[0006] When observed along the first direction, since the gap between at least part of the adjacent first buffer members and the second buffer members is smaller than the gap between the electrode assembly and the outer shell, when the secondary battery falls or vibrates, the overlapping part of the projections of the first buffer member and the second buffer member along the direction perpendicular to the first direction can come into contact before the electrode assembly impacts the outer shell, and at least part of the falling energy or vibration energy can act on the shear interface between the first buffer member and the second buffer member, thereby reducing the falling energy or vibration energy through the first buffer member and the second buffer member, which is beneficial to reduce the possibility of the electrode assembly impacting the outer shell and prolonging the service life of the secondary battery.

[0007] In one or more of the above embodiments, when viewed along the first direction, the maximum gap between adjacent first buffer members and second buffer members is smaller than the minimum gap between the electrode assembly and the housing. When the secondary battery is dropped or vibrated, more overlapping portions of the projections of the first buffer member and the second buffer member can come into contact before the electrode assembly impacts the housing, and more drop energy or vibration energy can act on the shear interface between the first buffer member and the second buffer member, which is beneficial to further reduce the possibility of the electrode assembly impacting the housing.

[0008] In one or more of the above embodiments, the first buffer and the second buffer are arranged alternately along the second direction and the third direction, the second direction is the length direction or width direction of the electrode assembly, and the first direction, the second direction and the third direction are perpendicular to each other. When the secondary battery falls or vibrates, the number of the first buffer and the second buffer that are in contact along the second direction and the third direction can be increased, which is conducive to reducing the possibility of the electrode assembly impacting the shell.

[0009] In one or more of the above embodiments, the first buffer is evenly distributed on the inner wall of the housing; and / or the second buffer is evenly distributed on the surface of the electrode assembly facing the first buffer. When the secondary battery falls or vibrates, the number of the first buffer and the second buffer in contact along the second direction and along the third direction can be increased, which is conducive to further reducing the possibility of the electrode assembly impacting the housing.

[0010] In one or more of the above embodiments, the shear modulus of the first buffer member is G 1 , 200MPa≤G 1 ≤1000MPa; and / or, the shear modulus of the second buffer is G 2 , 200MPa≤G 2 ≤1000Mpa. By setting 200MPa≤G 1 and / or 200MPa≤G 2, the rigidity of the first buffer and the second buffer is not too weak, so that the first buffer and the second buffer are not easy to tear, which is conducive to the first buffer and the second buffer to maintain the buffering effect. 1 ≤1000MPa and / or G 2 ≤1000MPa, the rigidity of the first buffer member and the second buffer member is not too strong, which can facilitate the elastic deformation of the first buffer member and the second buffer member, thereby reducing the possibility of the electrode assembly impacting the shell.

[0011] In one or more of the above embodiments, 400MPa≤G 1 ≤800MPa; and / or, 400MPa≤G 2 ≤800MPa. By setting 400MPa≤G 1 and / or 400MPa≤G 2 , which can make the first buffer and the second buffer less likely to tear, and is more conducive to maintaining the buffering effect of the first buffer and the second buffer. 1 ≤800MPa and / or G 2 ≤800MPa, which can make it easier for the first buffer member and the second buffer member to undergo elastic deformation, thereby further reducing the possibility of the electrode assembly impacting the outer shell.

[0012] In one or more of the above embodiments, along any same direction perpendicular to the first direction, the tear strength of the electrode assembly is τ 1 , the minimum value of the tear strength of the first buffer and the tear strength of the second buffer is τ 2 , 1.5N / cm 2 <τ 2 ≤τ 1 By setting 1.5N / cm 2 <τ 2 , the tear strength between the first buffer and the second buffer is not too small, which is helpful to reduce the possibility of the electrode assembly impacting the outer shell when the secondary battery falls or vibrates. 2 ≤τ 1 The tear strength of the first buffer member and the second buffer member is not too large, and the first buffer member and the second buffer member can be torn before the electrode assembly is torn, which is beneficial to reducing the risk of the electrode assembly being torn.

[0013] In one or more of the above embodiments, τ 1 -τ 2 ≤3N / cm 2 By setting τ 1 -τ 2 ≤3N / cm 2 , when satisfying τ2 ≤τ 1 Under the premise of 2 It is not too small, which helps to reduce the possibility of the electrode assembly impacting the shell.

[0014] In one or more of the above embodiments, the opposing surfaces of the first buffer and the second buffer are inclined in the first direction, which can increase the contact area between the first buffer and the second buffer, further reduce the drop energy or vibration energy, and further reduce the possibility of the electrode assembly impacting the housing.

[0015] In one or more of the above embodiments, along the first direction, the projection area of ​​the outermost electrode sheet of the electrode assembly is S 1 , the total projected area of ​​the first buffer and the second buffer is S 2 , 0.6≤S 2 / S 1 ≤1. By setting 0.6≤S 2 / S 1 ≤1, so that the arrangement area of ​​the first buffer member and the second buffer member will not be too small, which is beneficial to reduce the possibility of the electrode assembly impacting the shell.

[0016] In one or more of the above embodiments, along the first direction, the thickness of the first buffer member is D 1 , the thickness of the second buffer is D 2 , 2μm≤D 1 ≤20μm, 2μm≤D 2 ≤20μm. By setting 2μm≤D 1 and 2μm≤D 2 , so that the first buffer and the second buffer are not too thin, which is beneficial to ensure the thickness of the overlapping portion of the projection of the first buffer and the second buffer, thereby facilitating the first buffer and the second buffer to maintain the buffering effect. 1 ≤20μm and D 2 ≤20 μm, so that the first buffer member and the second buffer member are not too thick, which is beneficial to improving the energy density of the secondary battery.

[0017] In one or more of the above embodiments, the first buffer is columnar; and / or the second buffer is columnar. The first buffer and / or the second buffer are columnar, so that the first buffer and / or the second buffer are subjected to more uniform force, and the buffering effect is better, which is conducive to reducing the possibility of the electrode assembly impacting the shell.

[0018] In one or more of the above embodiments, the first buffer member contacts the surface of the electrode assembly facing the first buffer member, and the second buffer member contacts the inner wall of the outer shell, so that the contact area between the first buffer member and the second buffer member is larger and the buffering effect is better when the secondary battery falls or vibrates, which is beneficial to reduce the possibility of the electrode assembly impacting the outer shell.

[0019] In one or more of the above embodiments, the material of the first buffer and / or the second buffer includes styrene-butadiene rubber, which includes styrene and butadiene. Based on the total mass of the styrene-butadiene rubber, the mass percentage of styrene is 23% to 40%, and the mass percentage of butadiene is 60% to 77%. The first buffer and / or the second buffer includes the above materials and the mass percentage of the above materials is controlled within the above range, so that the required elasticity of the first buffer and / or the second buffer can be easily adjusted.

[0020] The second aspect of the present application provides an electrical device, comprising the secondary battery of the first aspect of the present application. The secondary battery has a relatively long service life, which is beneficial to prolonging the service life of the electrical device. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 A front view of a secondary battery provided in accordance with an embodiment of the present application.

[0022] Figure 2 A top view of a secondary battery provided in accordance with an embodiment of the present application.

[0023] Figure 3 For the first embodiment of this application Figure 1 Cross-section along the midline AA.

[0024] Figure 4 The second embodiment of this application is Figure 1 Cross-section along the midline AA.

[0025] Figure 5 The third embodiment of this application is Figure 1 Cross-section along the midline AA.

[0026] Figure 6 For along Figure 2 Cross-section along section line BB.

[0027] Figure 7 For along Figure 2 Cross-section along the center line CC.

[0028] Figure 8 A schematic diagram of an alternate arrangement of a first buffer component and a second buffer component provided in an embodiment of the present application.

[0029] Fig. 9An overall schematic diagram of an electrical device provided in one embodiment of the present application.

[0030] Main component symbols 1000, electrical equipment; 100, secondary battery; 10, shell; 101, receiving cavity; 102, first gap; 103, second gap; 104, third gap; 105, fourth gap; 106, fifth gap; 11, first shell; 111, bottom wall; 112, side wall; 12, second shell; 20, electrode assembly; 21, negative electrode plate; 211, negative electrode current collector; 212, negative electrode active material layer; 22, positive electrode plate; 221, positive electrode current collector; 222, positive electrode active material layer; 23, diaphragm; 30, first buffer; 40, second buffer; 50, tab; 51, negative electrode tab; 52, positive electrode tab; 60, negative electrode tab bundle; 70, positive electrode tab bundle; 80, pole; 90, insulating member; X, first direction; Y, second direction; Z, third direction. DETAILED DESCRIPTION

[0031] 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 of the embodiments.

[0032] It should be noted that when an element is considered to be "connected" to another element, it may be directly connected to the other element or there may be a centrally disposed element at the same time. When an element is considered to be "disposed on" another element, it may be directly disposed on the other element or there may be a centrally disposed element at the same time.

[0033] Unless otherwise specified, the term "plurality" as used herein means two or more than two.

[0034] The terms "first", "second", etc. are only used to distinguish different objects and shall not be understood as indicating or implying relative importance or implying the quantity, specific order or primary and secondary relationship of the indicated technical features.

[0035] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art to which the present application belongs. The terms used herein in the specification of the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0036] The embodiment of the present application provides a secondary battery, including a shell, an electrode assembly, a plurality of first buffers and a plurality of second buffers, the shell having a receiving cavity, the electrode assembly being arranged in the receiving cavity, the first buffer being arranged on the inner wall of the shell, and the second buffer being arranged on the surface of the electrode assembly facing the first buffer. Along a first direction, there is a first gap between the electrode assembly and the shell, the first buffer and the second buffer are located in the first gap, and the first direction is the thickness direction of the electrode assembly. Along a direction perpendicular to the first direction, the projection of the first buffer and the projection of the second buffer overlap at least partially. Observed along the first direction, at least part of the first buffer and the second buffer are arranged in an interlaced manner, and the gap between at least part of the adjacent first buffer and the second buffer is smaller than the gap between the electrode assembly and the shell. At least part of the first buffer and the second buffer are arranged in an interlaced manner, which means that some (greater than or equal to one) or all of the first buffers are arranged in an interlaced manner with the second buffer, and / or some (greater than or equal to one) or all of the second buffers are arranged in an interlaced manner with the first buffer.

[0037] In the secondary battery of the present application, when observed along the first direction, since the gap between at least part of the adjacent first buffer members and the second buffer members is smaller than the gap between the electrode assembly and the outer shell, when the secondary battery falls or vibrates, the overlapping portion of the projections of the first buffer member and the second buffer member along the direction perpendicular to the first direction can come into contact before the electrode assembly impacts the outer shell, and at least part of the falling energy or vibration energy can act on the shear interface between the first buffer member and the second buffer member, thereby reducing the falling energy or vibration energy through the first buffer member and the second buffer member, which is beneficial to reducing the possibility of the electrode assembly impacting the outer shell and increasing the service life of the secondary battery.

[0038] Some embodiments of the present application will be described below 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.

[0039] See also Figures 1 to 3 , an embodiment of the present application provides a secondary battery 100, including a housing 10, an electrode assembly 20, a plurality of first buffer members 30 and a plurality of second buffer members 40, the housing 10 having a receiving cavity 101, the electrode assembly 20 being disposed in the receiving cavity 101, the first buffer member 30 being disposed on the inner wall of the housing 10, and the second buffer member 40 being disposed on the surface of the electrode assembly 20 facing the first buffer member 30. The so-called plurality refers to one or more. In some embodiments, the first buffer member 30 is bonded to the inner wall of the housing 10, and the second buffer member 40 is bonded to the surface of the electrode assembly 20 facing the first buffer member 30. For example, the first buffer member 30 is solidified on the inner wall of the housing 10 after being melted, and the second buffer member 40 is solidified on the surface of the electrode assembly 20 facing the first buffer member 30 after being melted.

[0040] In some embodiments, the receiving cavity 101 is filled with an electrolyte, and the electrolyte includes an electrolyte salt. In some embodiments, the electrolyte salt includes at least one of an organic lithium salt or an inorganic lithium salt.

[0041] In some embodiments, the material of the housing 10 includes but is not limited to aluminum-plastic film or steel.

[0042] In some embodiments, see Figure 1 The housing 10 includes a first shell 11 and a second shell 12, and the first shell 11 and the second shell 12 are connected to form a receiving cavity 101. In some embodiments, the first shell 11 and the second shell 12 are connected along the thickness direction of the electrode assembly 20.

[0043] In some embodiments, when the material of the housing 10 is an aluminum-plastic film, the first housing 11 and the second housing 12 can be connected by melting. When the material of the housing 10 is steel, the first housing 11 and the second housing 12 can be connected by welding.

[0044] In some embodiments, the first housing 11 is the body of the housing 10, and the second housing 12 is the cover of the housing 10. Figure 3 The first housing 11 includes a bottom wall 111 and a side wall 112. The side wall 112 is disposed around the periphery of the bottom wall 111 and forms a recess with the bottom wall 111. The side wall 112 is connected to the second housing 12. In some other embodiments, the second housing 12 may also be formed with a recess.

[0045] See also Figure 3 The electrode assembly 20 is disposed in the receiving cavity 101. The electrode assembly 20 includes a negative electrode sheet 21, a positive electrode sheet 22 and a separator 23, and the separator 23 separates the negative electrode sheet 21 from the positive electrode sheet 22.

[0046] In some embodiments, the negative electrode sheet 21 and the positive electrode sheet 22 are respectively bonded to the separator 23 .

[0047] In some embodiments, see Figure 3 The electrode assembly 20 is a stacked structure, wherein a plurality of negative electrode sheets 21 and a plurality of positive electrode sheets 22 are alternately stacked, and a separator 23 is disposed between any adjacent negative electrode sheets 21 and positive electrode sheets 22 .

[0048] In some other embodiments, the electrode assembly 20 is a winding structure, in which a single negative electrode sheet 21 and a single positive electrode sheet 22 are stacked and wound, and the separator 23 is disposed between the negative electrode sheet 21 and the positive electrode sheet 22 .

[0049] In some embodiments, the negative electrode plate 21 includes a negative electrode current collector 211 and a negative electrode active material layer 212, and the negative electrode active material layer 212 is disposed on two opposite sides of the negative electrode current collector 211 along the thickness direction. The positive electrode plate 22 includes a positive electrode current collector 221 and a positive electrode active material layer 222, and the positive electrode active material layer 222 is disposed on two opposite sides of the positive electrode current collector 221 along the thickness direction.

[0050] In some embodiments, when the electrode assembly 20 is a stacked structure, if the negative electrode sheet 21 or the positive electrode sheet 22 is the outermost sheet of the electrode assembly 20 , the side of the current collector facing away from the interior of the electrode assembly 20 may not be provided with an active material layer.

[0051] In some embodiments, the negative electrode current collector 211 is made of copper foil, and the positive electrode current collector 221 is made of aluminum foil.

[0052] In some embodiments, the negative electrode active material layer 212 may be formed by coating the negative electrode active material on the negative electrode current collector 211, and the negative electrode active material layer 212 is bonded to the negative electrode current collector 211. The positive electrode active material layer 222 may be formed by coating the positive electrode active material on the positive electrode current collector 221, and the positive electrode active material layer 222 is bonded to the positive electrode current collector 221.

[0053] In some embodiments, the diaphragm 23 is an insulating film material such as a polyethylene film, a polypropylene film, a polyester film, or a polyimide film.

[0054] See also Figures 3 to 6 Along the first direction X, there is a first gap 102 between the electrode assembly 20 and the housing 10 , the first buffer member 30 and the second buffer member 40 are located in the first gap 102 , and the first direction X is the thickness direction of the electrode assembly 20 .

[0055] Along the direction perpendicular to the first direction X, the projection of the first buffer member 30 and the projection of the second buffer member 40 at least partially overlap. When viewed along the first direction X, at least part of the first buffer member 30 and the second buffer member 40 are arranged alternately. Figures 3 to 5 , along the second direction Y, the projection of the first buffer member 30 and the projection of the second buffer member 40 at least partially overlap, and at least part of the first buffer member 30 and the second buffer member 40 are arranged alternately. Figure 3 As shown, when the number of the first buffer members 30 is greater than or equal to two and the number of the second buffer members 40 is greater than or equal to two, the first buffer members 30 and the second buffer members 40 do not have to be completely staggered, but there is at least one staggered minimum unit, and the so-called staggered minimum unit includes one first buffer member 30 and one second buffer member 40. In some embodiments, refer to Figure 6 and Figure 7Along the third direction Z, the projection of the first buffer member 30 and the projection of the second buffer member 40 at least partially overlap, and at least part of the first buffer member 30 and the second buffer member 40 are alternately arranged.

[0056] When viewed along the first direction X, the gap between at least some adjacent first buffer members 30 and second buffer members 40 is smaller than the gap between the electrode assembly 20 and the housing 10. Figures 3 to 5 , along the second direction Y, the electrode assembly 20 and the housing 10 have a second gap 103, and along the second direction Y, there is a third gap 104 between the adjacent first buffer members 30 and second buffer members 40, and the third gap 104 is smaller than the second gap 103. In some embodiments, see Figure 6 and Figure 7 Along the third direction Z, the electrode assembly 20 and the housing 10 have a fourth gap 105 , and along the third direction Z, the adjacent first buffer member 30 and the second buffer member 40 have a fifth gap 106 , and the fifth gap 106 is smaller than the fourth gap 105 .

[0057] When observed along the first direction X, since the gap between the adjacent first buffer member 30 and the second buffer member 40 is smaller than the gap between the electrode assembly 20 and the housing 10, when the secondary battery 100 falls or vibrates, the overlapping portion of the projections of the first buffer member 30 and the second buffer member 40 can come into contact before the electrode assembly 20 impacts the housing 10 along the direction perpendicular to the first direction X, and at least part of the falling energy or vibration energy can act on the shear interface between the first buffer member 30 and the second buffer member 40, thereby reducing the falling energy or vibration energy through the first buffer member 30 and the second buffer member 40, which is conducive to reducing the possibility of the electrode assembly 20 impacting the housing 10 and improving the service life of the secondary battery 100. It should be understood that by reducing the possibility of the electrode assembly 20 impacting the housing 10, when the first housing 11 and the second housing 12 are separately arranged and connected, it is conducive to reducing the risk of the first housing 11 and the second housing 12 being separated and causing the secondary battery 100 to fail due to leakage.

[0058] The first direction X, the second direction Y, and the third direction Z are perpendicular to each other, the second direction Y may be the length direction or the width direction of the electrode assembly 20, and the third direction Z may be the length direction or the width direction of the electrode assembly 20. It should be understood that when the second direction Y is the length direction of the electrode assembly 20, the third direction Z is the width direction of the electrode assembly 20; when the second direction Y is the width direction of the electrode assembly 20, the third direction Z is the length direction of the electrode assembly 20.

[0059] In some embodiments, when viewed along the first direction X, the maximum gap between adjacent first buffer members 30 and second buffer members 40 is smaller than the minimum gap between the electrode assembly 20 and the housing 10. When the secondary battery 100 is dropped or vibrated, more overlapping portions of the projections of the first buffer member 30 and the second buffer member 40 can come into contact before the electrode assembly 20 impacts the housing 10, and more drop energy or vibration energy can act on the shear interface between the first buffer member 30 and the second buffer member 40, which is beneficial to further reduce the possibility of the electrode assembly 20 impacting the housing 10.

[0060] In some embodiments, see Figures 5 to 7 The opposing surfaces of the first buffer member 30 and the second buffer member 40 are inclined to the first direction X. The contact area between the first buffer member 30 and the second buffer member 40 can be increased, which is beneficial to further reduce the drop energy or vibration energy and further reduce the possibility of the electrode assembly 20 impacting the housing 10 .

[0061] In some embodiments, see Figure 8 , along the second direction Y and along the third direction Z, the first buffer members 30 and the second buffer members 40 are arranged alternately. When the secondary battery 100 falls or vibrates, the number of the first buffer members 30 and the second buffer members 40 that are in contact along the second direction Y and along the third direction Z can be increased, which is conducive to reducing the possibility of the electrode assembly 20 impacting the outer shell 10. In some embodiments, the first buffer members 30 are evenly distributed on the inner wall of the outer shell 10. In some embodiments, the second buffer members 40 are evenly distributed on the surface of the electrode assembly 20 facing the first buffer member 30. The so-called uniform distribution means that along the second direction Y and along the third direction Z, the gap between any two adjacent first buffer members 30 has an error of at most 10%, and the gap between any two adjacent second buffer members 40 has an error of at most 10%. When the secondary battery 100 falls or vibrates, the number of the first buffer members 30 and the second buffer members 40 that are in contact along the second direction Y and along the third direction Z can be increased, which is conducive to further reducing the possibility of the electrode assembly 20 impacting the outer shell 10.

[0062] In some embodiments, the tear strength of the electrode assembly 20 along the direction perpendicular to the first direction X is τ 1 , the minimum value of the tear strength of the first buffer member 30 and the tear strength of the second buffer member 40 is τ 2 , 1.5N / cm 2 <τ 2 ≤τ 1 By setting 1.5N / cm 2 <τ 2, the tear strength between the first buffer member 30 and the second buffer member 40 is not too small, which is helpful to reduce the possibility of the electrode assembly 20 impacting the outer shell 10 when the secondary battery 100 falls or vibrates. 2 ≤τ 1 The tear strength of the first buffer member 30 and the second buffer member 40 is not too large, and the first buffer member 30 and the second buffer member 40 can be torn before the electrode assembly 20 is torn, which is beneficial to reduce the risk of the electrode assembly 20 being torn.

[0063] The so-called τ 1 It refers to the shear stress required to completely tear the electrode assembly 20 under the action of a load perpendicular to the first direction X. The tearing of the electrode assembly 20 includes, but is not limited to, the peeling of the negative electrode active material layer 212 and the separator 23, the peeling of the negative electrode active material layer 212 and the negative electrode current collector 211, the peeling of the positive electrode active material layer 222 and the separator 23, the peeling of the positive electrode active material layer 222 and the positive electrode current collector 221, the tearing of the separator 23 itself, the tearing of the negative electrode active material layer 212 or the negative electrode current collector 211 itself, and the tearing of the positive electrode active material layer 222 or the positive electrode current collector 221 itself.

[0064] The so-called τ 2 It refers to the shear stress that can completely tear the first buffer 30 or the second buffer 40 under the load perpendicular to the first direction X. The load perpendicular to the first direction X may be caused by the secondary battery 100 falling or vibrating.

[0065] In some embodiments, τ 1 -τ 2 ≤3N / cm 2 By setting τ 1 -τ 2 ≤3N / cm 2 , when satisfying τ 2 ≤τ 1 Under the premise of 2 It is not too small, which is helpful to reduce the possibility of the electrode assembly 20 impacting the housing 10.

[0066] In some embodiments, along the first direction X, the thickness of the first buffer member 30 is D 1 , the thickness of the second buffer member 40 is D 2 , 2μm≤D 1 ≤20μm, 2μm≤D 2 ≤20μm. For example, D 1 The value of is 2μm, 3μm, 5μm, 10μm, 15μm, 20μm or any value between the listed endpoints, D2 The value of D is 2μm, 3μm, 5μm, 10μm, 15μm, 20μm or any value between the listed endpoints. 1 and 2μm≤D 2 , so that the first buffer member 30 and the second buffer member 40 are not too thin, which is beneficial to ensure the thickness of the overlapping portion of the first buffer member 30 and the second buffer member 40, thereby facilitating the first buffer member 30 and the second buffer member 40 to maintain the buffering effect. 1 ≤20μm and D 2 ≤20 μm, so that the first buffer 30 and the second buffer 40 are not too thick, which is beneficial to improve the energy density of the secondary battery 100. In some embodiments, along the direction perpendicular to the first direction X, the thickness of the overlapping portion of the projection of the first buffer 30 and the second buffer 40 is at least 2 μm.

[0067] In some embodiments, the first buffer member 30 contacts the surface of the electrode assembly 20 facing the first buffer member 30, and the second buffer member 40 contacts the inner wall of the outer shell 10. This enables the first buffer member 30 and the second buffer member 40 to have a larger contact area and a better buffering effect when the secondary battery 100 falls or vibrates, thereby reducing the possibility of the electrode assembly 20 impacting the outer shell 10.

[0068] In some embodiments, the first gap 102 is smaller than the maximum value of the thickness of the first buffer 30 and the thickness of the second buffer 40. When the secondary battery 100 is dropped or vibrated, the first buffer 30 and the second buffer 40 can come into contact, and the first buffer 30 and the electrode assembly 20 or the second buffer 40 and the housing 10 can also be frictional, which is conducive to reducing the possibility of the electrode assembly 20 impacting the housing 10.

[0069] In some embodiments, the material of the first buffer 30 includes styrene-butadiene rubber, which includes styrene and butadiene. Based on the total mass of the styrene-butadiene rubber, the mass percentage of styrene is 23% to 40%, and the mass percentage of butadiene is 60% to 77%. The first buffer 30 includes the above materials and the mass percentage of the above materials is adjusted within the above range, so that the required elasticity of the first buffer 30 can be easily adjusted.

[0070] In some embodiments, the material of the second buffer 40 includes styrene-butadiene rubber, which includes styrene and butadiene. Based on the total mass of the styrene-butadiene rubber, the mass percentage of styrene is 23% to 40%, and the mass percentage of butadiene is 60% to 77%. The second buffer 40 includes the above materials and the mass percentage of the above materials is controlled within the above range, which can facilitate the adjustment of the required elasticity of the second buffer 40. Among them, the mass percentage of styrene and butadiene can be appropriately adjusted according to the required elasticity of the first buffer 30 and the second buffer 40. For example, the mass percentage of butadiene can be increased, thereby improving the elasticity of the first buffer 30 and the second buffer 40.

[0071] In some embodiments, the shear modulus of the first buffer member 30 is G 1 , 200MPa≤G 1 ≤1000MPa. For example, G 1 The value of G is 200MPa, 300MPa, 500MPa, 700MPa, 1000MPa or any value between the listed endpoints. 1 , the rigidity of the first buffer member 30 is not too weak, so that the first buffer member 30 is not easy to tear, which is conducive to the first buffer member 30 and the second buffer member 40 maintaining the buffering effect. 1 ≤1000MPa, the rigidity of the first buffer member 30 is not too strong, which can facilitate the elastic deformation of the first buffer member 30, thereby reducing the possibility of the electrode assembly 20 impacting the housing 10.

[0072] In some embodiments, 400 MPa ≤ G 1 ≤800MPa. By setting 400MPa≤G 1 , which can make the first buffer member 30 less likely to tear, and is more conducive to maintaining the buffering effect of the first buffer member 30 and the second buffer member 40. 1 ≤800 MPa, which can make it easier for the first buffer member 30 to undergo elastic deformation, thereby further reducing the possibility of the electrode assembly 20 impacting the housing 10.

[0073] In some embodiments, the shear modulus of the second buffer member 40 is G 2 , 200MPa≤G 2 ≤1000Mpa. For example, G 2 The value of G is 200MPa, 300MPa, 500MPa, 700MPa, 1000MPa or any value between the listed endpoints. 2, the rigidity of the second buffer member 40 is not too weak, so that the second buffer member 40 is not easy to tear, which is conducive to maintaining the buffering effect of the first buffer member 30 and the second buffer member 40. 2 ≤1000MPa, the rigidity of the second buffer member 40 is not too strong, which can facilitate the elastic deformation of the second buffer member 40, thereby reducing the possibility of the electrode assembly 20 impacting the housing 10.

[0074] In some embodiments, 400 MPa ≤ G 2 ≤800MPa. By setting 400MPa≤G 2 , which can make the second buffer 40 less likely to tear, and is more conducive to maintaining the buffering effect of the first buffer 30 and the second buffer 40. 2 ≤800 MPa, which can facilitate the elastic deformation of the second buffer member 40 and help further reduce the possibility of the electrode assembly 20 impacting the housing 10.

[0075] In some embodiments, along the first direction X, the projection area of ​​the outermost electrode sheet of the electrode assembly 20 is S 1 The total projected area of ​​the first buffer member 30 and the second buffer member 40 is S 2 , 0.6≤S 2 / S 1 ≤1. For example, S 2 / S 1 The value of S is 0.6, 0.7, 0.8, 0.9, 1, or any value between the listed endpoints. 2 / S 1 ≤1, so that the arrangement area of ​​the first buffer 30 and the second buffer 40 is not too small, which is conducive to reducing the possibility of the electrode assembly 20 impacting the housing 10. It should be understood that when the electrode assembly 20 is a stacked structure, the outermost electrode sheet is the electrode sheet closest to the second buffer 40 among the electrode sheets of the electrode assembly 20 along the thickness direction of the electrode assembly 20. When the electrode assembly 20 is a winding structure, the outermost electrode sheet is the flat area of ​​the electrode sheet of the outermost winding located between the bending areas and close to the second buffer 40.

[0076] In some embodiments, the first buffer member 30 is cylindrical in shape, which can make the first buffer member 30 more evenly stressed and have a better buffering effect, thereby reducing the possibility of the electrode assembly 20 impacting the housing 10. It is understood that the first buffer member 30 can be conical, spherical or other shapes without affecting the purpose of the present invention.

[0077] In some embodiments, the second buffer member 40 is cylindrical, which can make the second buffer member 40 more evenly stressed and have a better buffering effect, thereby reducing the possibility of the electrode assembly 20 impacting the housing 10. It is understood that the second buffer member 40 can be conical, spherical or other shapes without affecting the purpose of the present invention.

[0078] In some embodiments, see Figure 6 The secondary battery 100 includes a tab 50 , and the tab 50 includes a negative electrode tab 51 . The negative electrode tab 51 is connected to the negative electrode collector 211 and extends out of the negative electrode collector 211 along the third direction Z.

[0079] In some embodiments, the negative electrode tab 51 is integrally formed with the negative electrode current collector 211. In some embodiments, the negative electrode tab 51 is welded to the negative electrode current collector 211.

[0080] In some embodiments, see Figure 6 The plurality of negative electrode tabs 51 are stacked in sequence along the first direction X and welded to form a negative electrode tab bundle 60. The negative electrode tab bundle 60 is bent in a direction opposite to the stacking direction of the plurality of negative electrode tabs 51 and then electrically connected to the housing 10.

[0081] In some embodiments, the negative electrode tab bundle 60 is welded to the housing 10. In some embodiments, the negative electrode tab bundle 60 is welded to the first shell 11.

[0082] In some embodiments, see Figure 7 The tab 50 includes a positive tab 52 , which is connected to the positive current collector 221 and extends out of the positive current collector 221 along the third direction Z.

[0083] In some embodiments, the positive electrode tab 52 is integrally formed with the positive electrode current collector 221. In some embodiments, the positive electrode tab 52 is connected to the positive electrode current collector 221 by welding.

[0084] In some embodiments, see Figure 7 The plurality of positive electrode tabs 52 are stacked in sequence along the first direction X and welded to form a positive electrode tab bundle 70. The positive electrode tab bundle 70 is bent in a direction opposite to the stacking direction of the plurality of positive electrode tabs 50 and then insulated and connected to the housing 10.

[0085] In some embodiments, see Figure 7 The secondary battery 100 includes a pole 80 , which is insulated and fixed to the housing 10 , and the positive electrode tab bundle 70 is electrically connected to the pole 80 .

[0086] In some embodiments, the positive electrode tab bundle 70 is connected to the pole 80 through an adapter (not shown), and the material of the adapter is one or more conductive materials such as copper, aluminum, nickel, and nickel alloy.

[0087] In some embodiments, the pole 80 is insulated and fixed to the first housing 11. Figure 7 The secondary battery 100 includes an insulating member 90 , which is disposed on the first housing 11 . Along the first direction X and the third direction Z, the pole 80 is spaced apart from the first housing 11 by at least a portion of the insulating member 90 .

[0088] See also Fig. 9 One embodiment of the present application provides an electric device 1000, comprising the secondary battery 100 as described above. The secondary battery 100 has a relatively high service life, which is beneficial to prolonging the service life of the electric device 1000. The electric device 1000 includes but is not limited to electronic devices such as mobile phones, tablet computers, and laptop computers.

[0089] In order to verify the effect of the scheme provided in the present application on the secondary battery 100, the inventor of the present application conducted the following experiment, which includes 1 group of comparative examples and 27 groups of embodiments, each group of comparative examples and embodiments includes 20 secondary batteries 100. The material of the shell 10 in the secondary battery 100 used in the comparative examples and embodiments is steel, the first shell 11 and the second shell 12 are welded, and the first shell 11 is the shell body of the shell 10, and the second shell 12 is the shell cover of the shell 10. The electrode assembly 20 in the secondary battery 100 is a stacked structure, and the outermost electrode sheet of the electrode assembly 20 is a single-sided negative electrode sheet 21. The first buffer 30 in the secondary battery 100 is bonded to the shell cover (i.e., the second shell 12) of the shell 10, and the second buffer 40 is bonded to the outermost electrode sheet of the electrode assembly 20. The first buffer 30 and the second buffer 40 are both columnar. Along the second direction Y and along the third direction Z, the first buffer 30 and the second buffer 40 are staggered. Along the first direction X, the total projection area S of the first buffer member 30 and the second buffer member 40 is 2 The projected area S of the outermost pole piece 1 Equal (S 1 and S 2 A 10% error is allowed between the two).

[0090] In the present application, the mass percentage of each material in the first buffer member 30 and the second buffer member 40 can be changed to obtain the τ required for the experiment. 2 The τ required for the experiment can be obtained by changing the mass percentage of each material in the negative electrode sheet 21, the positive electrode sheet 22 and the separator 23. 1 Among them, the determination of τ 1 and τ 2 The method is as follows: 1) Sample preparation: According to the τ to be measured 1 and τ 2, take out the to-be-tear sample 1 in which the first buffer member 30 is arranged on the second shell 12 and the second buffer member 40 is arranged on the outermost electrode sheet of the electrode assembly 20, and the to-be-tear sample 2 in which the diaphragm 23 is bonded to the negative electrode sheet 21 and the positive electrode sheet 22 from the finished secondary battery 100, and use a blade to cut out the tear test sample 1 and the tear test sample 2 with a test area of ​​5 cm×5 cm from the different samples taken out.

[0091] 2) Test: Fix the tear test specimens 1 and 2 to the test fixture of the high-speed rail tensile machine in sequence, so that the thickness direction of the tear test specimens 1 and 2 is perpendicular to the force direction of the high-speed rail tensile machine. Select the shear mode, set the shear angle to 0 degrees, and the shear speed to 25±2mm / min. Start the test until the shear interface of the tear test specimens 1 and 2 is completely torn.

[0092] 3) Value: The ratio of the maximum tensile force to the test area when the shear interface of the tear test sample is completely torn is τ 2 The ratio of the maximum tensile force to the test area when the shear interface of the tear test sample 2 is completely torn is taken as τ 1 The value of .

[0093] In the present application, the drop pass rate of the secondary battery 100 and the tearing rate of the electrode assembly 20 can be used to reflect the τ 1 and τ 2 The relationship between the drop test and the electrode assembly 20 has an impact on the secondary battery 100. The drop pass rate refers to the proportion of secondary batteries 100 that have no leakage or fire after the drop test, and the tearing rate refers to the proportion of secondary batteries 100 that have tearing in the electrode assembly 20 after the drop test. The drop test method is as follows: 1) 20 secondary batteries 100 of each comparative example and embodiment are grouped as one, and the 20 secondary batteries 100 are sequentially placed in a special fixture and freely dropped from a height of 1.5 meters onto a marble surface; each secondary battery 100 is dropped three times in total, and the position sequence of the secondary battery 100 facing the marble surface during each drop is: upper shell cover - lower bottom wall - upper right corner - lower right corner - upper left corner - lower left corner; 2) After each round of dropping, check the appearance of the secondary battery 100. If the secondary battery 100 in the round leaks or catches fire, stop dropping immediately.

[0094] 3) After all 20 secondary batteries 100 in each group have been dropped, the secondary batteries 100 are disassembled, and the number of secondary batteries 100 that have not leaked or caught fire is counted as N, and the number of secondary batteries 100 whose electrode assemblies 20 have been torn is counted as F. The drop pass rate of the secondary batteries 100 in this group is N / 20, and the tearing rate of the electrode assemblies 20 is F / 20.

[0095] After the test, the experimental results are recorded in Tables 1 to 3: Table 1 Table 2 Table 3 In Table 1, the difference between Comparative Example 1 and Example 1 is that the housing 10 and the electrode assembly 20 of Comparative Example 1 are bonded and fixed by an adhesive in the prior art, and the smaller of the peel strength between the adhesive and the housing 10 and the peel strength between the adhesive and the electrode assembly 20 is 1 N / cm 2 .

[0096] In Tables 1 to 3, the shear modulus G of Examples 1 to 15 is 1 and G 2 Both are 1100MPa, τ 1 and τ 2 Different. τ in Examples 16 to 27 1 and τ 2 Compared with τ in Example 5 1 and τ 2 Similarly, the shear modulus G in Examples 16 to 27 is 1 or G 2 Compared with the shear modulus G in Example 5 1 or G 2 different.

[0097] In Table 1, the drop pass rate of comparative example 1 is lower than that of embodiment 1, that is, the present application can reduce the drop energy or vibration energy through the first buffer member 30 and the second buffer member 40, which is beneficial to reduce the possibility of the electrode assembly 20 impacting the outer shell 10.

[0098] In Table 1, the drop pass rates of Example 1 and Example 2 are lower, which is due to τ 2 ≤1.5N / cm 2 When a drop test is performed, the first buffer member 30 and the second buffer member 40 are easily torn, so that the electrode assembly 20 impacts the housing 10 and causes leakage.

[0099] In Table 1, the drop pass rates of Examples 3 to 15 are significantly greater than those of Examples 1 and 2. This is because τ 2 >1.5N / cm 2, when performing a drop test, the first buffer 30 and the second buffer 40 are less likely to tear, which can reduce the possibility of leakage caused by the electrode assembly 20 impacting the housing 10. The tearing incidence rates of Examples 3, 6, 9 and 12 are equivalent to the drop pass rate, the tearing incidence rates of Examples 4 and 5 are significantly lower than that of Example 3, the tearing incidence rates of Examples 7 and 8 are significantly lower than that of Example 6, the tearing incidence rates of Examples 10 and 11 are significantly lower than that of Example 9, and the tearing incidence rates of Examples 13 and 14 are significantly lower than that of Example 12. That is, the present application sets τ 2 ≤τ 1 , which helps to reduce the risk of the electrode assembly 20 being torn.

[0100] In Table 1, the drop pass rates of Example 8, Example 11, Example 14 and Example 15 are all significantly greater than the drop pass rate of Example 5, that is, the present application achieves a drop pass rate of 1. 1 -τ 2 ≤3N / cm 2 , which helps to reduce the possibility of the electrode assembly 20 impacting the shell 10.

[0101] In Tables 2 and 3, the drop pass rates of Example 16 and Example 17 are similar, but the shear modulus G of Example 17 is 1 Greater than the shear modulus G of Example 16 1 The drop pass rates of Example 22 and Example 23 are comparable, but the shear modulus G of Example 23 is 2 Greater than the shear modulus G of Example 22 2 According to Examples 17 to 21 and Example 5, the drop pass rates of Example 21 and Example 5 are similar, but the shear modulus G of Example 5 is 1 Greater than the shear modulus G of Example 21 1 When G 1 When ≤1000MPa, as the shear modulus G 1 The drop pass rate of the secondary battery 100 gradually decreases, and the drop pass rate of the secondary battery 100 gradually increases; according to Examples 22 to 27 and Example 5, the drop pass rates of Example 27 and Example 5 are equivalent, but the shear modulus G of Example 5 is 2 Greater than the shear modulus G of Example 27 2 When G 2 When ≤1000MPa, as the shear modulus G 2 The drop pass rate of the secondary battery 100 gradually increases. That is, the present application sets 200MPa≤G 1 and / or 200MPa≤G 2, which can make the first buffer member 30 and / or the second buffer member 40 less likely to tear, thereby facilitating the first buffer member 30 and the second buffer member 40 to maintain a buffering effect. 1 ≤1000MPa and / or G 2 ≤1000MPa, which is helpful to reduce the possibility of leakage caused by the electrode assembly 20 impacting the shell 10.

[0102] In Tables 2 and 3, the drop pass rates of Example 17 and Example 18 are similar, but the shear modulus G of Example 18 is 1 Greater than the shear modulus G of Example 17 1 The drop pass rates of Example 22 and Example 23 are comparable, but the shear modulus G of Example 23 is 2 Greater than the shear modulus G of Example 23 2 According to Examples 17 to 21, the drop pass rates of Examples 17 to 20 are significantly greater than the drop pass rate of Example 21. According to Examples 22 to 27, the drop pass rates of Examples 22 to 26 are significantly greater than the drop pass rate of Example 27. That is, the present application sets 400MPa≤G 1 and / or 400MPa≤G 2 , which can make the first buffer 30 and / or the second buffer 40 less likely to tear, and is more conducive to maintaining the buffering effect between the first buffer 30 and the second buffer 40. 1 ≤800MPa and / or G 2 ≤800MPa, which is beneficial to further reduce the possibility of leakage caused by the electrode assembly 20 impacting the shell 10.

[0103] In addition, those skilled in the art should recognize that the above embodiments are only used to illustrate the present application, and are not intended to limit the present application. As long as they are within the essential scope 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: include: A housing having a receiving cavity; An electrode assembly, wherein the electrode assembly is disposed in the receiving cavity, and a first gap is formed between the electrode assembly and the housing along a first direction, wherein the first direction is a thickness direction of the electrode assembly; A plurality of first buffer members, wherein the first buffer members are arranged on the inner wall of the shell and located in the first gap; A plurality of second buffer members, wherein the second buffer members are disposed on a surface of the electrode assembly facing the first buffer member and are located in the first gap; Wherein, along a direction perpendicular to the first direction, a projection of the first buffer member and a projection of the second buffer member at least partially overlap; When viewed along the first direction, at least some of the first buffer members and the second buffer members are arranged alternately, and the gap between at least some of the adjacent first buffer members and the second buffer members is smaller than the gap between the electrode assembly and the housing.

2. The secondary battery according to claim 1, characterized in that: When viewed along the first direction, a maximum gap between adjacent first buffer members and second buffer members is smaller than a minimum gap between the electrode assembly and the housing.

3. The secondary battery according to claim 1, characterized in that: The first buffer members and the second buffer members are arranged alternately along the second direction and the third direction, the second direction is the length direction or the width direction of the electrode assembly, and the first direction, the second direction and the third direction are perpendicular to each other.

4. The secondary battery according to claim 3, characterized in that: The first buffer member is evenly distributed on the inner wall of the shell; and / or the second buffer member is evenly distributed on the surface of the electrode assembly facing the first buffer member.

5. The secondary battery according to claim 1, characterized in that: The shear modulus of the first buffer component is G1, 200 MPa≤G1≤1000 MPa; and / or the shear modulus of the second buffer component is G2, 200 MPa≤G2≤1000 MPa.

6. The secondary battery according to claim 5, characterized in that: 400 MPa≤G1≤800 MPa; and / or, 400 MPa≤G2≤800 MPa.

7. The secondary battery according to claim 1, characterized in that: In any same direction perpendicular to the first direction, the tear strength of the electrode assembly is τ1, and the minimum value of the tear strength of the first buffer and the tear strength of the second buffer is τ2, 1.5 N / cm 2 <τ2≤τ1.

8. The secondary battery according to claim 7, characterized in that: τ1-τ2≤3N / cm 2 。 9. The secondary battery according to claim 1, characterized in that: The opposing surfaces of the first buffer member and the second buffer member are inclined with respect to the first direction.

10. The secondary battery according to claim 1, characterized in that: Along the first direction, the projection area of ​​the outermost electrode sheet of the electrode assembly is S1, the total projection area of ​​the first buffer component and the second buffer component is S2, and 0.6≤S2 / S1≤1.

11. The secondary battery according to claim 1, characterized in that: Along the first direction, the thickness of the first buffer member is D1, the thickness of the second buffer member is D2, 2 μm≤D1≤20 μm, and 2 μm≤D2≤20 μm.

12. The secondary battery according to claim 1, characterized in that: The first buffer is columnar; and / or the second buffer is columnar.

13. The secondary battery according to claim 1, characterized in that: The first buffer member contacts a surface of the electrode assembly facing the first buffer member, and the second buffer member contacts an inner wall of the housing.

14. The secondary battery according to claim 1, characterized in that: The material of the first buffer and / or the second buffer includes styrene-butadiene rubber, which includes styrene and butadiene. Based on the total mass of the styrene-butadiene rubber, the mass percentage of the styrene is 23% to 40%, and the mass percentage of the butadiene is 60% to 77%.

15. An electrical equipment, characterized in that: The invention comprises the secondary battery according to any one of claims 1 to 14.

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