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 first friction piece and a second friction piece, the shell is provided with a containing cavity, the electrode assembly is arranged in the containing cavity, the first friction piece is arranged on the shell, and the second friction piece is arranged on the electrode assembly. The first friction piece and the second friction piece are oppositely arranged in the first direction, and the first direction is the thickness direction of the electrode assembly. In the direction perpendicular to the first direction, the first friction piece and the second friction piece can move relatively and can generate friction during relative movement, the tearing strength of the electrode assembly is tau 1, the anti-sliding strength of the first friction piece and the second friction piece is tau 2, and 1 N / cm < 2 > < tau 2 < = tau 1. The anti-sliding strength of the first friction piece and the second friction piece is not small, and the possibility that the electrode assembly impacts the shell is reduced. And the anti-sliding strength of the first friction piece and the second friction piece is not relatively high, so that the risk that the electrode assembly is torn is reduced, 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 prone to tearing under the action of the drop energy or vibration energy. In particular, as the number of cycles of the secondary battery increases, the expansion force generated by the secondary battery gradually increases, the deformation degree of the electrode assembly is aggravated, and it is more likely to tear, thereby causing the secondary battery to fail.

[0004] In view of the above situation, it is necessary to provide a secondary battery that can reduce the possibility of tearing of the electrode assembly, 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 first friction member, and a second friction member. The housing has a receiving cavity, the electrode assembly is disposed in the receiving cavity, the first friction member is disposed in the housing, and the second friction member is disposed in the electrode assembly. The first friction member and the second friction member are disposed relative to each other along a first direction, and the first direction is the thickness direction of the electrode assembly. The first friction member and the second friction member can move relative to each other in a direction perpendicular to the first direction, and can generate friction during the relative movement, and the tear strength of the electrode assembly is τ 1 , the anti-slip strength of the first friction member and the second friction member is τ 2 , 1N / cm 2 <τ 2 ≤τ 1 .

[0006] By setting the first friction member and the second friction member to move relative to each other, friction can occur between the first friction member and the second friction member and a buffering effect can be generated. 2 <τ 2, the anti-slip strength of the first friction member and the second friction member is not too small, and when the secondary battery falls or vibrates, the friction buffering effect between the first friction member and the second friction member can reduce the falling energy or vibration energy, which is beneficial to reduce the possibility of the electrode assembly impacting the shell. 2 ≤τ 1 The anti-slip strength of the first friction member and the second friction member is not too large, and the first friction member and the second friction member can slide relative to each other before the electrode assembly is torn, which is beneficial to reducing the risk of the electrode assembly being torn, thereby helping to increase the service life of the secondary battery.

[0007] In one or more of the above embodiments, 1N / cm 2 ≤τ 1 -τ 2 ≤3N / cm 2 . Considering that as the number of secondary battery cycles increases, τ 1 By setting 1N / cm 2 ≤τ 1 -τ 2 , which can reduce the τ of the secondary battery after cycling 1 Reduced to less than τ 2 This helps reduce the risk of the electrode assembly being torn when the secondary battery is dropped or vibrated after cycling. 1 -τ 2 ≤3N / cm 2 , when satisfying τ 2 ≤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.

[0008] In one or more of the above embodiments, along the first direction, the surface where the maximum projection area of ​​the second friction member is located includes the contact surface between the second friction member and the electrode assembly.

[0009] In one or more of the above embodiments, along the direction perpendicular to the first direction, the minimum value of the tear strength of the first friction member and the tear strength of the second friction member is τ 3 , τ 2 <τ 3 The risk of the first friction member and the second friction member being torn before relative sliding can be reduced, which is beneficial for maintaining the friction buffering effect between the first friction member and the second friction member.

[0010] In one or more of the above embodiments, along a direction perpendicular to the first direction, the cross-sectional area of ​​the first friction member and the second friction member is greater than or equal to the friction area of ​​the first friction member and the second friction member.

[0011] In one or more of the above embodiments, the second friction member is bonded to the outermost pole piece of the electrode assembly, and along the first direction, the projection area of ​​the outermost pole piece is S 1 , the friction area between the first friction member and the second friction member is S 2 , 0.5≤S 2 / S 1 ≤1. By setting 0.5≤S 2 / S 1 ≤1, which can ensure that the friction area between the first friction member and the second friction member is not too small, which is beneficial to improve τ 2 The value of is beneficial to further reduce the possibility of the electrode assembly impacting the casing.

[0012] In one or more of the above embodiments, the friction surface of the first friction member and / or the second friction member is provided with staggered protrusions and depressions, which can enhance the friction buffering effect between the first friction member and the second friction member, and is conducive to further reducing the possibility of the electrode assembly impacting the housing.

[0013] In one or more of the above embodiments, the first friction member and the second friction member each independently have one of a single-layer structure, a double-layer structure and a three-layer structure, the single-layer structure includes a single adhesive layer, the double-layer structure includes a single base layer and a single adhesive layer bonded to one surface of the base layer along the thickness direction of the base layer, and the three-layer structure includes a single base layer and two adhesive layers bonded to two surfaces of the base layer along the thickness direction of the base layer. The thickness direction of the base layer is parallel to the first direction.

[0014] In one or more of the above embodiments, the thickness of the single-layer structure is D 1 , the thickness of the double-layer structure is D 2 , the thickness of the three-layer structure is D 3 , 1μm≤D 1 ≤30μm, 6μm≤D 2 ≤30μm, 7μm≤D 3 ≤30μm. By setting 1μm≤D 1 、6μm≤D 2 and 7μm≤D 3 , which can make the single-layer structure, double-layer structure and triple-layer structure not too thin, which is beneficial to reduce the possibility of fatigue damage of the first friction member and the second friction member under continuous friction, thereby making the first friction member and the second friction member maintain the friction buffering effect. 1 ≤30μm, D 2 ≤30μm and D 3 ≤30μm, so that the first friction member and the second friction member are not too thick, which is beneficial to improving the energy density of the secondary battery.

[0015] In one or more of the above embodiments, the material of the adhesive layer includes polyacrylate and curing agent, the mass percentage of polyacrylate is 95% to 99%, and the mass percentage of curing agent is 1% to 4%. And / or, the material of the base layer includes base resin, tackifying resin, polyether polyol and microcrystals, the mass percentage of base resin is 30% to 40%, the mass percentage of tackifying resin is 54% to 69%, the mass percentage of polyether polyol is 0% to 5%, and the mass percentage of microcrystals is 1% to 2%. The material of the adhesive layer includes the above materials and the mass percentage of the above materials in the adhesive layer is regulated within the above range, and / or the material of the base layer includes the above materials and the mass percentage of the above materials in the base layer is regulated within the above range, so that 1N / cm 2 <τ 2 ≤τ 1 .

[0016] In one or more of the above embodiments, the first friction member is in contact or bonded with the second friction member. By making the first friction member in contact with the second friction member, friction and buffering can be generated during relative movement. By making the first friction member and the second friction member bonded, the friction buffering effect between the first friction member and the second friction member can be enhanced, which is conducive to further reducing the possibility of the electrode assembly impacting the housing.

[0017] In one or more of the above embodiments, the friction coefficient between the first friction member and the second friction member is f, 0.5≤f≤1.3. By setting 0.5≤f, τ 2 By setting f≤1.3, τ 2 It is not too large, which helps reduce the risk of the electrode assembly being torn.

[0018] In one or more of the above embodiments, 0.8≤f≤1.1. By setting 0.8≤f, the possibility of the electrode assembly impacting the housing is further reduced. By setting f≤1.1, the risk of the electrode assembly being torn is further reduced.

[0019] In one or more of the above embodiments, the shear modulus of the first friction member is G 1 , 200MPa≤G 1 ≤1000Mpa; and / or, the shear modulus of the second friction member is G 2 , 200MPa≤G 2 ≤1000MPa. By setting 200MPa≤G 1 and / or 200MPa≤G 2, which can make the rigidity of the first friction member and the second friction member not too weak, and is conducive to reducing the possibility of fatigue damage of the first friction member and the second friction member under continuous friction, so as to make the first friction member and the second friction member maintain the friction buffering effect. 1 ≤1000MPa and / or G 2 ≤1000MPa, which can make the rigidity of the first friction member and the second friction member not too strong, and can facilitate the elastic deformation of the first friction member and the second friction member, which is beneficial to reduce the possibility of the electrode assembly impacting the shell.

[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 along Figure 1 Cross-section along the midline AA.

[0024] Figure 4 A schematic diagram of a single-layer structure provided in one embodiment of the present application.

[0025] Figure 5 A schematic diagram of a double-layer structure provided in one embodiment of the present application.

[0026] Figure 6 A schematic diagram of a three-layer structure provided in one embodiment of the present application.

[0027] Figure 7 For along Figure 2 Cross-section along section line BB.

[0028] Figure 8 For along Figure 2 Cross-section along section line CC.

[0029] Fig. 9 An 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, glue layer; 103, base layer; 104, protrusion; 105, depression; 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 friction member; 40, second friction member; 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, comprising a housing, an electrode assembly, a first friction member, and a second friction member. The housing has a receiving cavity, the electrode assembly is arranged in the receiving cavity, the first friction member is arranged in the housing, and the second friction member is arranged in the electrode assembly. The first friction member and the second friction member are arranged relative to each other along a first direction, and the first direction is the thickness direction of the electrode assembly. In a direction perpendicular to the first direction, the first friction member and the second friction member can move relative to each other, and can generate friction during relative movement, and the tear strength of the electrode assembly is τ1 , the anti-slip strength of the first friction member and the second friction member is τ 2 , 1N / cm 2 <τ 2 ≤τ 1 .

[0037] In the secondary battery of the present application, the first friction member and the second friction member are arranged to move relative to each other, and friction and buffering effect can be generated when the first friction member and the second friction member move relative to each other. 2 <τ 2 , the anti-slip strength of the first friction member and the second friction member is not too small, and when the secondary battery falls or vibrates, the friction buffering effect between the first friction member and the second friction member can reduce the falling energy or vibration energy, which is beneficial to reduce the possibility of the electrode assembly impacting the shell. 2 ≤τ 1 The anti-slip strength of the first friction member and the second friction member is not too large, and the first friction member and the second friction member can slide relative to each other before the electrode assembly is torn, which is beneficial to reducing the risk of the electrode assembly being torn, thereby helping to increase 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 The embodiment of the present application provides a secondary battery 100, including a housing 10, an electrode assembly 20, a first friction member 30 and a second friction member 40. The housing 10 has a receiving cavity 101, the electrode assembly 20 is disposed in the receiving cavity 101, the first friction member 30 is disposed in the housing 10, and the second friction member 40 is disposed in the electrode assembly 20. In some embodiments, the first friction member 30 is bonded to the housing 10, and the second friction member 40 is bonded to the electrode assembly 20.

[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 Figure 3 , the first friction member 30 and the second friction member 40 are arranged opposite to each other along the first direction X, and the first direction X is the thickness direction of the electrode assembly 20. In the direction perpendicular to the first direction X, the first friction member 30 and the second friction member 40 can move relative to each other, and can generate friction during the relative movement. The first friction member 30 and the second friction member 40 can be in contact in advance, which can facilitate the friction and buffering effect during the relative movement. Alternatively, the first friction member 30 and the second friction member 40 can be in contact after the secondary battery 100 has undergone cyclic expansion. When the electrode assembly 20 and the housing 10 have a relative movement tendency or relative movement occurs, a buffering effect can be generated between the first friction member 30 and the second friction member 40. For example, the first friction member 30 and the second friction member 40 are in contact in advance, so that friction is generated when the first friction member 30 and the second friction member 40 move relative to each other, and a buffering effect is generated.

[0055] In the direction perpendicular to the first direction X, the tear strength of the electrode assembly 20 is τ 1 , the anti-slip strength of the first friction member 30 and the second friction member 40 is τ 2 , 1N / cm 2 <τ 2 ≤τ 1 The direction perpendicular to the first direction X includes a second direction Y and a third direction Z, and the first direction X, the second direction Y and the third direction Z are perpendicular to each other. In some embodiments, the second direction Y may be the width direction of the electrode assembly 20, and the third direction Z may be the length direction of the electrode assembly 20.

[0056] The so-called τ 1It 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.

[0057] The so-called τ 2 It refers to the shear stress required to enable relative sliding between the first friction member 30 and the second friction member 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.

[0058] The above is achieved by setting 1N / cm 2 <τ 2 , the anti-slip strength of the first friction member 30 and the second friction member 40 is not too small, and when the secondary battery 100 falls or vibrates, the friction buffering effect between the first friction member 30 and the second friction member 40 can reduce the falling energy or vibration energy, which is beneficial to reduce the possibility of the electrode assembly 20 impacting the housing 10. By setting τ 2 ≤τ 1 , the anti-slip strength of the first friction member 30 and the second friction member 40 is not too large, and the first friction member 30 and the second friction member 40 can slide relative to each other before the electrode assembly 20 is torn, which is conducive to reducing the risk of the electrode assembly 20 being torn, thereby facilitating 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 shell 11 and the second shell 12 are separately arranged and connected, it is conducive to reducing the risk of the first shell 11 and the second shell 12 being separated, resulting in leakage failure of the secondary battery 100.

[0059] In some embodiments, 1N / cm 2 ≤τ 1 -τ 2 ≤3N / cm 2 . Considering that as the number of cycles of the secondary battery increases, τ 1 By setting 1N / cm 2 ≤τ 1 -τ 2 , which can reduce the secondary battery 100 after cycling τ 1 Reduced to less than τ 2The possibility of the electrode assembly 20 being torn when the secondary battery 100 is dropped or vibrated after cycling is reduced. 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.

[0060] In some embodiments, when the electrode assembly 20 moves along the first direction X, the first friction member 30 collides with the second friction member 40 , which helps to reduce the risk of tearing or deformation of the electrode assembly 20 .

[0061] In some embodiments, along the first direction X, the surface where the maximum projection area of ​​the second friction member 40 is located includes the contact surface between the second friction member 40 and the electrode assembly 20 .

[0062] In some embodiments, along the direction perpendicular to the first direction X, the minimum value of the tear strength of the first friction member 30 and the tear strength of the second friction member 40 is τ 3 , τ 2 <τ 3 The so-called τ 3 It refers to the minimum value of the shear stress required to completely tear the first friction member 30 and the shear stress required to completely tear the second friction member 40 under the load perpendicular to the first direction X. It can reduce the risk of the first friction member 30 and the second friction member 40 tearing themselves before relative sliding occurs, which is conducive to maintaining the friction buffering effect between the first friction member 30 and the second friction member 40.

[0063] In some embodiments, along a direction perpendicular to the first direction X, the cross-sectional areas of the first friction member 30 and the second friction member 40 are greater than the friction areas of the first friction member 30 and the second friction member 40 .

[0064] In some embodiments, along the direction perpendicular to the first direction X, the cross-sectional area of ​​the first friction member 30 and the second friction member 40 is equal to the friction area of ​​the first friction member 30 and the second friction member 40. Without affecting the purpose of the invention of the present application, considering the precision of production and processing, when there is a 5% error between the cross-sectional area of ​​the first friction member 30 and the second friction member 40 and the friction area of ​​the first friction member 30 and the second friction member 40, it can also be considered that the cross-sectional area of ​​the first friction member 30 and the second friction member 40 is equal to the friction area of ​​the first friction member 30 and the second friction member 40.

[0065] In some embodiments, the friction coefficient between the first friction member 30 and the second friction member 40 is f, 0.5≤f≤1.3. For example, the value of f is 0.5, 0.6, 0.7, 0.8, 1, 1.3 or any value between the listed endpoint values. By setting 0.5≤f, τ 2 It is not too small, which is helpful to reduce the possibility of the electrode assembly 20 impacting the housing 10. By setting f≤1.3, τ 2 It is not too large, which helps to reduce the risk of the electrode assembly 20 being torn.

[0066] In some embodiments, 0.8≤f≤1.1. By setting 0.8≤f, the possibility of the electrode assembly 20 impacting the housing 10 is further reduced. By setting f≤1.1, the risk of the electrode assembly 20 being torn is further reduced.

[0067] In some embodiments, the first friction member 30 has one of a single-layer structure, a double-layer structure, and a triple-layer structure. In some embodiments, the second friction member 40 has one of a single-layer structure, a double-layer structure, and a triple-layer structure. Figure 4 The so-called single-layer structure includes a single adhesive layer 102. Figure 5 The so-called double-layer structure includes a single adhesive layer 102 and a single base layer 103, and the adhesive layer 102 is bonded to a surface of the base layer 103 along the thickness direction of the base layer 103. Figure 6 The so-called three-layer structure includes two adhesive layers 102 and a single base layer 103, and the two adhesive layers 102 are bonded to two surfaces of the base layer 103 along the thickness direction of the base layer 103. The thickness direction of the base layer 103 is parallel to the first direction X.

[0068] In some embodiments, both the first friction member 30 and the second friction member 40 are single-layer structures, and the rubber layer 102 of the first friction member 30 can move relative to the rubber layer 102 of the second friction member 40 along the direction perpendicular to the first direction X. In some embodiments, both the first friction member 30 and the second friction member 40 are double-layer structures, and the base layer 103 of the first friction member 30 can move relative to the base layer 103 of the second friction member 40 along the direction perpendicular to the first direction X. In some embodiments, both the first friction member 30 and the second friction member 40 are three-layer structures, and the rubber layer 102 of the first friction member 30 can move relative to the rubber layer 102 of the second friction member 40 along the direction perpendicular to the first direction X. It should be understood that the present application also includes the situations where the first friction part 30 is a single-layer structure and the second friction part 40 is a double-layer structure, the first friction part 30 is a single-layer structure and the second friction part 40 is a three-layer structure, the first friction part 30 is a double-layer structure and the second friction part 40 is a single-layer structure, the first friction part 30 is a double-layer structure and the second friction part 40 is a three-layer structure, the first friction part 30 is a three-layer structure and the second friction part 40 is a single-layer structure, and the first friction part 30 is a three-layer structure and the second friction part 40 is a double-layer structure.

[0069] In some embodiments, the thickness of the single layer structure is D 1 , the thickness of the double-layer structure is D 2 , the thickness of the three-layer structure is D 3 , 1μm≤D 1 ≤30μm, 6μm≤D 2 ≤30μm, 7μm≤D 3 ≤30μm. For example, D 1 The value of is 1μm, 5μm, 10μm, 15μm, 20μm, 30μm or any value between the listed endpoints, D 2 The value of D is 6μm, 10μm, 15μm, 20μm, 30μm or any value between the listed endpoints. 3 The value of D is 7μm, 10μm, 15μm, 20μm, 30μm or any value between the listed endpoints. 1 、6μm≤D 2 and 7μm≤D 3 , which can make the single-layer structure, double-layer structure and triple-layer structure not too thin, which is beneficial to reduce the possibility of fatigue damage of the first friction member 30 and the second friction member 40 under continuous friction, thereby helping to maintain the friction buffering effect between the first friction member 30 and the second friction member 40. By setting D 1 ≤30μm, D 2 ≤30μm and D 3≤30 μm, so that the first friction member 30 and the second friction member 40 are not too thick, which is beneficial to improving the energy density of the secondary battery 100.

[0070] In some embodiments, the material of the adhesive layer 102 includes polyacrylate and a curing agent, the mass percentage of the polyacrylate is 95% to 99%, and the mass percentage of the curing agent is 1% to 4%. Among them, the mass percentage of the polyacrylate can be increased to improve the viscosity of the adhesive layer 102. The curing agent includes but is not limited to epoxy resin and polyamide. The material of the adhesive layer 102 includes the above materials and the mass percentage of the above materials in the adhesive layer 102 is controlled within the above range, which can facilitate 1N / cm 2 <τ 2 ≤τ 1 .

[0071] In some embodiments, the material of the base layer 103 includes a base resin, a tackifying resin, a polyether polyol and microcrystals, the mass percentage of the base resin is 30% to 40%, the mass percentage of the tackifying resin is 54% to 69%, the mass percentage of the polyether polyol is 0% to 5%, and the mass percentage of the microcrystals is 1% to 2%. Among them, the base resin includes a SIS block copolymer (i.e., a triblock copolymer composed of polystyrene-polyisoprene-polystyrene), wherein the block ratio of polystyrene and polyisoprene can be appropriately adjusted according to the required rigidity and mechanical strength of the base layer 103. For example, the block ratio of polystyrene can be increased, thereby improving the rigidity and mechanical strength of the base layer 103. The tackifying resin includes hydrogenated resins, which can increase the mass percentage of the tackifying resin, thereby improving the peel strength between the base layer 103 and the adhesive layer 102. The polyether polyol is prepared by a polyaddition reaction of an initiator (i.e., a compound containing an active hydrogen group) with ethylene oxide, propylene oxide, and butylene oxide under catalysis. The material of the base layer 103 includes the above materials and the mass percentage of the above materials in the base layer 103 is controlled within the above range, so that 1N / cm 2 <τ 2 ≤τ 1 .

[0072] In some embodiments, the first friction member 30 is bonded to the second friction member 40. For example, at least one of the first friction member 30 and the second friction member 40 is a single-layer structure or a three-layer structure, so that the first friction member 30 and the second friction member 40 are bonded by the adhesive layer 102. The friction buffering effect between the first friction member 30 and the second friction member 40 can be enhanced, which is conducive to further reducing the possibility of the electrode assembly 20 impacting the housing 10.

[0073] In some embodiments, the friction surface of the first friction member 30 is distributed with staggered protrusions 104 and depressions 105. In some embodiments, the friction surface of the second friction member 40 is distributed with staggered protrusions 104 and depressions 105. For example, see Figure 4 and Figure 6 When the first friction member 30 or the second friction member 40 is a single-layer structure or the first friction member 30 or the second friction member 40 is a three-layer structure, the protrusion 104 and the recess 105 are provided on the rubber layer 102; please refer to Figure 5 When the first friction member 30 or the second friction member 40 is a double-layer structure, the protrusion 104 and the recess 105 are provided on the base layer 103. The friction buffering effect between the first friction member 30 and the second friction member 40 can be enhanced, which is beneficial to further reduce the possibility of the electrode assembly 20 impacting the housing 10. In some embodiments, the protrusion 104 of the first friction member 30 is at least partially embedded with the recess 105 of the second friction member 40, and the recess 105 of the first friction member 30 is at least partially embedded with the protrusion 104 of the second friction member 40.

[0074] In some embodiments, the shear modulus of the first friction member 30 is G 1 , 200MPa≤G 1 ≤1000MPa. For example, G 1 The value of G is 200MPa, 300MPa, 400MPa, 600MPa, 800MPa, 1000MPa or any value between the listed endpoints. 1 , the rigidity of the first friction member 30 will not be too weak, which is beneficial to reduce the possibility of fatigue damage of the first friction member 30 under continuous friction, thereby helping the first friction member 30 to maintain the friction buffering effect. 1 ≤1000 MPa, which can make the rigidity of the first friction member 30 not too strong, and can facilitate the elastic deformation of the first friction member 30, which is beneficial to reduce the possibility of the electrode assembly 20 impacting the housing 10.

[0075] In some embodiments, the shear modulus of the second friction member 40 is G 2 , 200MPa≤G 2 ≤1000MPa. For example, G 2 The value of G is 200MPa, 300MPa, 400MPa, 600MPa, 800MPa, 1000MPa or any value between the listed endpoints. 2 , the rigidity of the second friction member 40 will not be too weak, which is beneficial to reduce the possibility of fatigue damage of the second friction member 40 under continuous friction, thereby helping the second friction member 40 to maintain the friction buffering effect.2 ≤1000 MPa, which can make the rigidity of the second friction member 40 not too strong, and can facilitate the elastic deformation of the second friction member 40, which is beneficial to reduce the possibility of the electrode assembly 20 impacting the housing 10.

[0076] In some embodiments, the second friction member 40 is bonded to the outermost pole piece of the electrode assembly 20. Along the first direction X, the projection area of ​​the outermost pole piece is S 1 , the friction area between the first friction member 30 and the second friction member 40 is S 2 , 0.5≤S 2 / S 1 ≤1. For example, S 2 / S 1 The value of S is 0.5, 0.6, 0.7, 0.8, 0.9, 1, or any value between the listed endpoints. 2 / S 1 ≤1, which can ensure that the friction area between the first friction member 30 and the second friction member 40 is not too small, which is beneficial to improve τ 2 The value of is beneficial to further reduce the possibility of the electrode assembly 20 impacting the shell 10.

[0077] It should be understood that when the electrode assembly 20 is a stacked structure, the outermost pole piece is the pole piece closest to the second friction member 40 among the pole pieces of the electrode assembly 20 along the thickness direction of the electrode assembly 20. When the electrode assembly 20 is a wound structure, the outermost pole piece is the flat area of ​​the outermost winding pole piece located between the bending areas and close to the second friction member 40.

[0078] In some embodiments, see Figure 7 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 7 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 8 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 8 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 8 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 8 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 solution provided in the present application on the secondary battery 100, the inventor of the present application conducted the following experiment, which includes 8 groups of comparative examples and 26 groups of embodiments, each of which 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 friction member 30 and the second friction member 40 in the secondary battery 100 are both double-layer structures, the glue layer 102 of the first friction member 30 is bonded to the shell cover (i.e., the second shell 12) of the shell 10, the glue layer 102 of the second friction member 40 is bonded to the outermost pole piece of the electrode assembly 20, the base layer 103 of the first friction member 30 is in contact with the base layer 103 of the second friction member 40, and the second friction member 40 is arranged in the center relative to the outermost pole piece of the electrode assembly 20. Along the first direction X, the projections of the glue layer 102 and the base layer 103 overlap, and the friction area S of the first friction member 30 and the second friction member 40 is 1.3×10. 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 negative electrode sheet 21, the positive electrode sheet 22 and the separator 23 can be changed to obtain the τ required for the experiment. 1 Among them, the determination of τ 1 The method is as follows: 1) Sample preparation: The separator 23, the negative electrode sheet 21 and the positive electrode sheet 22 which are still bonded are taken out from the finished secondary battery 100 as a sample to be torn, and a tear test sample with a test area of ​​1 cm×1 cm is cut out from the taken sample to be torn with a blade.

[0091] 2) Test: Fix the tear test specimen to the test fixture of the high-speed rail tensile testing machine. When fixing, make the thickness direction of the tear test specimen perpendicular to the force direction of the high-speed rail tensile testing 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 specimen 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 specimen is completely torn is taken as τ 1 The value of .

[0093] In the present application, the mass percentage of each material in the first friction member 30 and the second friction member 40 can be changed to obtain the τ required for the experiment. 2 Among them, the determination of τ2 The method is as follows: 1) placing the finished secondary battery 100 in an environment of 25±1°C; 2) charging with a constant current of 3C and discharging with a constant current of 1C so that the secondary battery 100 is cycled for 800 times, and then the expansion force generated by the secondary battery 100 is measured by an expansion force tester; 3) Take out the first friction member 30 and the shell cover that remain bonded from the secondary battery 100 as the sliding sample, and take out the second friction member 40 and the outermost pole piece that remain bonded as the sliding sample, and use a blade to cut out a sliding test sample with a test area of ​​3 cm×3 cm from the taken out sliding sample; 4) Fix the sliding test sample to the test slider of the friction coefficient tester, wherein the outermost pole piece is located between the second friction member 40 and the test slider, and the second friction member 40 is located at the outermost side away from the test slider. Fix the sliding sample on the horizontal test bench to ensure that the sliding test sample is parallel to the sliding sample on the horizontal test bench. Set the slider speed to 60±2mm / min. Start the test so that the sliding test sample starts to move on the sliding sample. After stopping, the reading of the friction coefficient tester is the friction coefficient between the test samples. 5) Repeat step 4 for 5 times and take the average value; 6) Calculate the product of the expansion force generated by the secondary battery 100 and the friction coefficient, and divide it by the friction area S between the first friction member 30 and the second friction member 40 2 , the resulting ratio is τ 2 The value of .

[0094] 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.

[0095] 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.

[0096] After the test, the experimental results are recorded in Table 1, Table 2 and Table 3: Table 1 Table 2 Table 3 In Tables 1 to 3, the shear modulus G of Comparative Examples 1 to 8, Examples 1 to 9, and Examples 22 to 26 are 1 and G 2 Both are 1100MPa, τ 1 and τ 2 Different. τ in Examples 10 to 21 1 and τ 2 Compared with τ in Example 2 1 and τ 2 Similarly, the shear modulus G in Examples 10 to 21 is 1 or G 2 Compared with the shear modulus G in Example 2 1 or G 2 Compared with Comparative Examples 1 to 8 and Examples 1 to 21, Examples 22 to 26 were subjected to the drop test after being cycled 800 times.

[0097] In Table 1, the drop pass rates of Comparative Examples 1 to 6 are all close to 0%, which is due to τ 2 ≤1N / cm 2 When the drop test is performed, the first friction member 30 and the second friction member 40 are prone to relative slippage, so that the electrode assembly 20 impacts the housing 10 and causes leakage. The tearing rate of Comparative Examples 1 and 4 is equivalent to the drop pass rate. This is because τ 2 >τ 1 In the part of the secondary battery 100 that passed the drop test, the drop energy is transmitted to the electrode assembly 20 through the first friction member 30 and the second friction member 40, so that the electrode assembly 20 is torn. The tearing incidence rates of Comparative Examples 2 and 3 are lower than that of Comparative Example 1, and the tearing incidence rates of Comparative Examples 5 and 6 are lower than that of Comparative Example 4. This is because τ 2 ≤τ1 In the portion of the secondary batteries 100 that pass the drop test, the possibility that the drop energy is transmitted to the electrode assembly 20 through the first friction member 30 and the second friction member 40 is low, so the possibility that the electrode assembly 20 is torn is low.

[0098] In Table 1, the drop pass rates of Comparative Examples 7 and 8 are significantly greater than those of Comparative Examples 1 to 6. This is because τ 2 >1N / cm 2 When the drop test is performed, the first friction member 30 and the second friction member 40 are not likely to slide relative to each other, which can reduce the possibility of leakage caused by the electrode assembly 20 impacting the housing 10. The tearing rate of Comparative Examples 7 and 8 is equivalent to the drop pass rate. This is because τ 2 >τ 1 In the portion of the secondary batteries 100 that pass the drop test, the drop energy is transferred to the electrode assembly 20 through the first friction member 30 and the second friction member 40 , so that the electrode assembly 20 is torn.

[0099] In Table 1, the drop pass rates of Examples 1 to 9 are significantly greater than the drop pass rates of Comparative Examples 1 to 6. That is, the present application sets τ 2 >1N / cm 2 , which can reduce the possibility of leakage caused by the electrode assembly 20 impacting the housing 10.

[0100] In Table 1, the tearing incidence rates of Example 3 and Example 4 are significantly lower than that of Comparative Example 7, and the tearing incidence rates of Example 7 and Example 8 are significantly lower than that of Comparative Example 8. That is, the present application sets τ 2 ≤τ 1 , which helps to reduce the risk of the electrode assembly 20 being torn.

[0101] In Table 1, the drop pass rates of Example 4, Example 6, Example 8 and Example 9 are all significantly greater than the drop pass rate of Example 2, that is, the present application achieves a higher drop pass rate by setting τ 1 -τ 2 ≤3N / cm 2 , which helps to reduce the possibility of the electrode assembly 20 impacting the shell 10.

[0102] In Table 2, the drop pass rates of Example 10 and Example 11 are similar, but the shear modulus G of Example 11 is 1 Greater than the shear modulus G of Example 10 1 According to Examples 11 to 15 and Example 2, the drop pass rates of Example 15 and Example 2 are similar, but the shear modulus G of Example 2 is 1 Greater than the shear modulus G of Example 151 When G 1 When ≤1000MPa, as the shear modulus G 1 The drop pass rate of Example 16 and Example 17 is similar, but the shear modulus G of Example 17 is 2 Greater than the shear modulus G of Example 16 2 According to Examples 17 to 21 and Example 2, the drop pass rates of Example 21 and Example 2 are similar, but the shear modulus G of Example 2 is 2 Greater than the shear modulus G of Example 21 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 is helpful to reduce the possibility of fatigue damage of the first friction member 30 and the second friction member 40 under continuous friction, so as to maintain the friction buffering effect between the first friction member 30 and the second friction member 40. 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.

[0103] In Table 3, the tearing rate of the secondary battery in Example 22 after 100 cycles and 800 cycles is significantly greater than the tearing rate of the secondary battery in Examples 23 to 26 after 100 cycles and 800 cycles, and the tearing rate of the secondary battery in Example 25 after 100 cycles and 800 cycles is equivalent to the tearing rate of the secondary battery in Example 26 after 100 cycles and 800 cycles, that is, the present application sets 1N / cm 2 ≤τ 1 -τ 2 ≤3N / cm 2 This helps to reduce the risk of the electrode assembly 20 being torn when the secondary battery 100 is dropped or vibrated after cycling.

[0104] 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; a first friction member, wherein the first friction member is disposed on the housing; a second friction member, the second friction member being disposed on the electrode assembly; Wherein, the first friction member and the second friction member are arranged opposite to each other along a first direction, and the first direction is a thickness direction of the electrode assembly; In a direction perpendicular to the first direction, the first friction member and the second friction member can move relative to each other and can generate friction during the relative movement. The tear strength of the electrode assembly is τ1, and the anti-slip strength of the first friction member and the second friction member is τ2, 1N / cm 2 <τ2≤τ1.

2. The secondary battery according to claim 1, characterized in that: 1N / cm 2 ≤τ1-τ2≤3N / cm 2 。 3. The secondary battery according to claim 1, characterized in that: Along the first direction, the surface where the maximum projection area of ​​the second friction member is located includes a contact surface between the second friction member and the electrode assembly.

4. The secondary battery according to claim 3, characterized in that: Along a direction perpendicular to the first direction, a minimum value of the tear strength of the first friction member and the tear strength of the second friction member is τ3, and τ2<τ3.

5. The secondary battery according to claim 4, characterized in that: Along a direction perpendicular to the first direction, cross-sectional areas of the first friction member and the second friction member are greater than or equal to friction areas of the first friction member and the second friction member.

6. The secondary battery according to claim 3, characterized in that: The second friction member is bonded to the outermost pole piece of the electrode assembly. Along the first direction, the projection area of ​​the outermost pole piece is S1, and the friction area between the first friction member and the second friction member is S2; 0.5≤S2 / S1≤1.

7. The secondary battery according to claim 1, characterized in that: The friction surface of the first friction member and / or the second friction member is provided with staggered protrusions and depressions.

8. The secondary battery according to claim 1, characterized in that: The first friction member and the second friction member each independently have one of a single-layer structure, a double-layer structure and a three-layer structure, the single-layer structure includes a single glue layer, the double-layer structure includes a single base layer and a single glue layer bonded to one surface of the base layer along the thickness direction of the base layer, and the three-layer structure includes a single base layer and two glue layers bonded to two surfaces of the base layer along the thickness direction of the base layer; the thickness direction of the base layer is parallel to the first direction.

9. The secondary battery according to claim 8, characterized in that: The thickness of the single-layer structure is D1, the thickness of the double-layer structure is D2, and the thickness of the triple-layer structure is D3, 1 μm≤D1≤30 μm, 6 μm≤D2≤30 μm, and 7 μm≤D3≤30 μm.

10. The secondary battery according to claim 8, characterized in that: The material of the adhesive layer includes polyacrylate and a curing agent, the mass percentage of the polyacrylate is 95% to 99%, and the mass percentage of the curing agent is 1% to 4%; and / or, the material of the base layer includes a matrix resin, a tackifying resin, a polyether polyol and microcrystals, the mass percentage of the matrix resin is 30% to 40%, the mass percentage of the tackifying resin is 54% to 69%, the mass percentage of the polyether polyol is 0% to 5%, and the mass percentage of the microcrystals is 1% to 2%.

11. The secondary battery according to claim 1 or 8, characterized in that: The first friction member is in contact with or bonded to the second friction member.

12. The secondary battery according to claim 1, characterized in that: The friction coefficient between the first friction member and the second friction member is f, and 0.5≤f≤1.

3.

13. The secondary battery according to claim 12, characterized in that: 0.8≤f≤1.1。 14. The secondary battery according to claim 1, characterized in that: The shear modulus of the first friction member is G1, 200 MPa≤G1≤1000 MPa; and / or the shear modulus of the second friction member is G2, 200 MPa≤G2≤1000 MPa.

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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