Secondary battery, battery pack, and electronic device

Abstract

The utility model provides a secondary battery, a battery pack and an electronic device. The secondary battery comprises a shell which comprises an end wall and a side wall arranged around the end wall, and the end wall and the side wall define a containing cavity; the electrode assembly is located in the containing cavity and comprises a winding structure formed by stacking and winding a positive plate, a diaphragm and a negative plate, the winding structure comprises a first end provided with a positive tab and a second end provided with a negative tab in the height direction, and the direction from the second end to the first end is a preset direction; the first insulating film is arranged on the periphery, close to the first end, of the winding structure in a surrounding mode by at least one circle, the first insulating film comprises a preset section exceeding the outer end face of the positive pole lug in the preset direction, the preset section extends in the direction close to the end wall, and the value range of the included angle between the extending direction of the preset section and the height direction is 0-60 degrees; therefore, wrinkles capable of storing electrolyte are prevented from being formed on the first insulating film, and the safety of the battery is improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to secondary battery field, especially a kind of secondary battery, battery pack and electronic device. BACKGROUND

[0002] In recent years, with the rapid development of electric vehicles, consumer electronics, new energy storage systems, for electric vehicles, battery technology is an important factor concerning its development.

[0003] In the development of battery technology, how to improve the safety of battery is an urgent technical problem to be solved in battery technology. CONTENT OF UTILITY MODEL

[0004] The utility model wants to solve the technical problems to overcome the above-mentioned technical problems of prior art, provide a kind of secondary battery, battery pack and electronic device.

[0005] The utility model is through the following technical scheme to solve the above-mentioned technical problems:

[0006] A kind of secondary battery, it is characterized in that, it includes:

[0007] Shell, including end wall and the side wall being set around the end wall, the end wall and the side wall are surrounded and form the accommodating cavity;

[0008] Electrode assembly, in the accommodating cavity, the electrode assembly includes positive sheet, diaphragm and negative sheet and is stacked and is wound and forms winding structure, the winding structure includes the first end being provided with positive pole lug and the second end being provided with negative pole lug along height direction, the second end to the first end is preset direction;

[0009] First insulating film, at least one circle of the winding structure is surrounded close to the first end, along the preset direction, the first insulating film includes the preset segment that exceeds the outer end surface of the positive pole lug, the preset segment extends towards close to the end wall direction, the extension direction of the preset segment and the included angle of the height direction is 0 degree-60 degrees.

[0010] In the technical solution, the first insulating film is not bent but adhered and attached to the first current collecting disc in the radial direction of the electrode assembly by setting the included angle between the extension direction of the preset section of the first insulating film and the height direction to be 0-60 degrees, so that the adhesion and attachment to the first current collecting disc does not form a wrinkle capable of storing electrolyte, and the electrolyte in the wrinkle can penetrate into the shell to cause corrosion of the shell, thereby improving the safety of the battery; and the first insulating film includes a preset section that exceeds the outer surface of the positive electrode tab, and the shell material of the cylindrical battery (such as 4680 / 4695 / 46120 / 46150 cylindrical battery) is steel, which can have higher strength, and the steel shell is often electrically connected to the negative electrode tab and is negatively charged. The design of the utility model can form electrical insulation between the positive electrode tab and the shell, thereby increasing the safety of the battery.

[0011] Preferably, the secondary battery further comprises a first current collecting disc located between the positive electrode tab and the end wall of the shell in the height direction, the first current collecting disc comprises a pole connecting portion and a positive electrode tab connecting portion connected together, the positive electrode tab connecting portion is electrically connected to the positive electrode tab, and the pole connecting portion is electrically connected to the pole;

[0012] The first insulating film comprises a substrate and a glue layer provided on part of the surface of the substrate, along the preset direction, the substrate comprises a first area exceeding the positive electrode tab connecting portion away from one side of the electrode assembly, and the first area is not covered with the glue layer; and / or,

[0013] The secondary battery further comprises a first insulating seal located between the first current collecting disc and the end wall in the height direction, and along the preset direction, the edge of the first insulating film does not exceed one side of the first insulating seal away from the electrode assembly.

[0014] Preferably, along the preset direction, the substrate comprises a second area covered with the glue layer and a third area not covered with the glue layer, and the third area comprises the first area, or the third area coincides with the first area;

[0015] The width of the substrate along the height direction is W, and the width of the second area along the height direction is w, and the value range of w / W is 0.12-0.8.

[0016] Preferably, the first insulating film is fixedly connected to the first insulating seal.

[0017] Preferably, the positive tab is a flat tab, and the positive tab is formed with a flat surface along the height direction; along the preset direction, the distance between the first insulating film and the flat surface is d, and the distance between the inner surface of the end wall and the flat surface is D, and the value of d / D is in the range of 0.1-0.99.

[0018] Preferably, the secondary battery further comprises a second insulating film, and the second insulating film is arranged around the outer periphery of the winding structure, and along the height direction, the second insulating film is located between the first end and the second end.

[0019] Along the radial direction of the winding structure, the first insulating film and the second insulating film do not overlap in the projection.

[0020] The material of the substrate of the second insulating film is PI or PET; and / or,

[0021] The thickness ratio of the second insulating film to the first insulating film is in the range of 0.8-1.1; and / or,

[0022] The peeling strength of the first insulating film is 2-7 times the peeling strength of the second insulating film.

[0023] Preferably, the second insulating film is continuously arranged along the circumferential direction of the winding structure and does not overlap, forming a winding structure uncovered area in the outer periphery of the winding structure which is not covered by the second insulating film, and the overlapping part of the first insulating film along the circumferential direction of the winding structure falls at least partially in the winding structure uncovered area along the height direction.

[0024] Preferably, the secondary battery is a cylindrical battery, and the secondary battery further comprises:

[0025] A pole is arranged through the end wall, and the pole is electrically connected to the positive tab through the first current collector; the pole is provided with a liquid injection through hole along the height direction;

[0026] And / or,

[0027] The accommodation cavity of the shell is provided with an opening away from one end of the end wall; the shell further comprises a crimping portion, and the crimping portion is formed at one end of the side wall close to the opening and is recessed towards the inside of the shell;

[0028] The secondary battery further comprises:

[0029] A cover plate is installed at the opening;

[0030] A second insulating seal is arranged around the periphery of the cover plate to insulate and seal the cover plate and the shell;

[0031] A second current collecting disc is arranged between the electrode assembly and the cover plate and is electrically connected to the shell, and a connecting piece of the second current collecting disc is arranged on a side of the crimping portion facing the electrode assembly and is welded to the crimping portion;

[0032] and / or,

[0033] The material of the substrate of the first insulating film is PI.

[0034] A battery pack comprising the secondary battery as described above.

[0035] An electronic device comprising the battery pack as described above.

[0036] The positive progress effect of the utility model lies in:

[0037] The utility model discloses the preset segment of first insulating film's extension direction and the included angle of height direction's value range is 0 degree-60 degrees, that is to say, the preset segment is not bent and is adhered and is covered on the first current collecting disc with the positive pole lug electric connection along the radial direction of electrode assembly, to avoid adhering and covering on the first current collecting disc and form the wrinkle that can store electrolyte, and the electrolyte in the wrinkle can be infiltrated into the shell, and the safety of battery is improved, and the first insulating film includes the preset segment of the outer surface of positive pole lug, and the shell material of large cylindrical battery (such as 4680 / 4695 / 46120 / 46150 etc. cylindrical battery) is steel, can have higher strength, and the steel shell is often electrically connected to the negative pole lug and is negatively charged, and the design of the utility model can form the electrical insulation between the positive pole lug and the shell, and the safety of battery is improved.

[0038] The utility model discloses a secondary battery still includes the pole, and the pole is seted with the injection liquid through -hole along the height direction, and the injection liquid through -hole sets up corresponding to the first end of electrode assembly, and the electrolyte flows into the shell by the injection liquid through -hole, and through the specific structure that the extension direction and the included angle of height direction's value range of the preset segment of first insulating film's at the first end are 0 degree-60 degrees, the electrolyte that can effectively avoid by the injection liquid through -hole injection enters between first insulating film and the shell, thereby improving the electrolyte infiltration efficiency when the positive pole injection. BRIEF DESCRIPTION OF DRAWINGS

[0039] FIG. 1 It is the structure schematic diagram of secondary battery of an embodiment of the utility model.

[0040] FIG. 2 It is the sectional structure schematic diagram of secondary battery of an embodiment of the utility model.

[0041] FIG. 3 It is FIG. 2 It is the local amplification structure schematic diagram of part A.

[0042] FIG. 4 For FIG. 2 Partial enlarged structural schematic view of middle B part.

[0043] FIG. 5 Partial structural schematic view of another embodiment of secondary battery of the utility model one embodiment.

[0044] FIG. 6 Partial structural schematic view of still another embodiment of secondary battery of the utility model one embodiment.

[0045] FIG. 7 Three-dimensional structural schematic view of electrode assembly of secondary battery of the utility model one preferable embodiment.

[0046] FIG. 8 Sectional structural schematic view of electrode assembly of secondary battery of the utility model one preferable embodiment.

[0047] FIG. 9 Partial structural schematic view of first insulating film of secondary battery of the utility model one preferable embodiment when unfolding.

[0048] FIG. 10 Structural schematic view of battery pack of the utility model one preferable embodiment.

[0049] FIG. 11 Structural schematic view of electronic device of the utility model one preferable embodiment.

[0050] Explanation of reference numerals

[0051] Electronic device 1000

[0052] Battery pack 100

[0053] Working part 300

[0054] Box body 310

[0055] Box cover 320

[0056] Secondary battery 1

[0057] Shell 10

[0058] End wall 11

[0059] Side wall 12

[0060] Accommodating cavity 13

[0061] Opening 14

[0062] Pressing portion 15

[0063] Electrode assembly 20

[0064] Winding structure 201

[0065] Positive electrode sheet 21

[0066] Positive electrode tab 211

[0067] Positive electrode sheet start end 217

[0068] Positive electrode sheet end end 218

[0069] Separator 22

[0070] Separator start end 221

[0071] Separator end end 222

[0072] Negative electrode sheet 23

[0073] Negative electrode sheet start end 237

[0074] Negative electrode sheet end end 238

[0075] First current collector disc 31

[0076] Pole connecting portion 311

[0077] Positive electrode tab connecting portion 312

[0078] Second current collector disc 32

[0079] First insulating film 40

[0080] Prescribed section 401

[0081] First section 4011

[0082] Second section 4012

[0083] Base material 41

[0084] First region 411

[0085] Second region 412

[0086] Third region 413

[0087] Adhesive layer 42

[0088] First insulating seal 50

[0089] Second insulating film 60

[0090] Pole 70

[0091] Liquid injection through hole 71

[0092] Cover plate 80

[0093] Second insulating seal 90

[0094] Height direction H of winding structure

[0095] Radial direction R of the winding structure

[0096] Circumferential direction P of the winding structure

[0097] Pre-set direction Q DETAILED DESCRIPTION

[0098] A preferred embodiment is described below in conjunction with the accompanying drawings so as to make the present application more comprehensible and complete.

[0099] As shown in FIGS. 1 to 6 , the present embodiment provides a secondary battery 1. The secondary battery 1 comprises a housing 10, an electrode assembly 20 and a first insulating film 40.

[0100] The housing 10 comprises an end wall 11 and a side wall 12 arranged around the end wall 11, and the end wall 11 and the side wall 12 are arranged to form a receiving cavity 13 for accommodating the electrode assembly 20, electrolyte and other necessary components of the battery. The connection between the end wall 11 and the side wall 12 can be achieved in various ways, for example, it can be in the form of one-piece stamping, one-piece casting or separate welding.

[0101] As shown in FIG. 7 and FIG. 8 , the electrode assembly 20 is located in the receiving cavity 13, and the electrode assembly 20 comprises a positive electrode sheet 21, a separator 22 and a negative electrode sheet 23 stacked and wound to form a winding structure 201, the winding structure 201 comprises a first end provided with a positive electrode tab 211 and a second end provided with a negative electrode tab in the height direction H, and the second end to the first end is a pre-set direction Q.

[0102] The first insulating film 40 is arranged around the outer periphery of the winding structure 201 close to the first end for at least one turn, and along the pre-set direction Q, the first insulating film 40 comprises a pre-set section 401 extending beyond the outer end surface of the positive electrode tab 211, the pre-set section 401 extends towards the direction close to the end wall 11, and the angle α between the extension direction of the pre-set section 401 and the height direction H is in the range of 0-60 degrees.

[0103] In this way, by setting the angle a between the extension direction of the preset section 401 of the first insulating film 40 and the height direction H to be in the range of 0-60 degrees, that is, the preset section is not bent but adhered and attached to the first current collector plate 31 electrically connected to the positive electrode tab 211 along the radial direction R of the electrode assembly 20, so that the adhesion and attachment to the first current collector plate 31 will not form a fold that can store electrolyte, and the electrolyte in the fold will penetrate into the shell 10, causing corrosion to the shell 10, thereby improving the safety of the battery; and the first insulating film 40 includes a preset section 401 that extends beyond the outer surface of the positive electrode tab 211, and the shell material of the cylindrical battery (such as 4680 / 4695 / 46120 / 46150 cylindrical battery) is steel, which can have higher strength, and the steel shell is often electrically connected to the negative electrode tab and is negatively charged. The design of the present embodiment can form electrical insulation between the positive electrode tab 211 and the shell 10, thereby increasing the safety of the battery. The preset section 401 extends beyond the outer end surface of the positive electrode tab 211 along the preset direction Q, and the outer end surface refers to the outer end surface (highest point) of the positive electrode tab 211 along the preset direction Q.

[0104] It should be noted that the angle a between the extension direction of the preset section 401 of the first insulating film 40 and the height direction H is an acute angle formed by the extension direction of the preset section 401 and the height direction H, and the value of the acute angle is in the range of 0-60 degrees. Please refer to FIG. 4 In an embodiment of the present embodiment, when the angle a between the extension direction of the preset section 401 of the first insulating film 40 and the height direction H is 0 degrees, that is, the preset section 401 is arranged along the height direction H at this time. However, it is not limited to this. Please refer to FIG. 5 In another embodiment of the present embodiment, due to the placement of the first insulating film 40 or the placement of the battery, the first insulating film 40 extending along the height direction H will be slightly bent or inclined, so that the angle a between the extension direction of the preset section 401 of the first insulating film 40 and the height direction H becomes 10 degrees, 15 degrees, 30 degrees, 40 degrees, 55 degrees or an angle less than or equal to 60 degrees. In addition, the first insulating film 40 is arranged around the outer periphery of the winding structure 201 near the first end for at least one turn, so that the first insulating film 40 has an overlapping portion along the radial direction R along the circumferential direction P of the winding structure 201, and along the radial direction R of the winding structure 201, the first insulating film 40 is located between the electrode assembly 20 and the side wall 12 of the shell 10.

[0105] Preferably, the angle a between the extending direction of the preset section 401 of the first insulating film 40 and the height direction H is in the range of 0-30 degrees, that is, the part of the first insulating film 40 beyond the outer surface of the positive tab 211 is arranged parallel or substantially parallel to the height direction H of the electrode assembly 20, which can better avoid the formation of folds capable of storing electrolyte when the first insulating film 40 is bonded and attached on the first current collecting plate 31, resulting in corrosion of the shell; and can better form electrical insulation between the positive tab 211 and the shell 10, increasing the safety of the battery.

[0106] It should be further noted that when the preset section 401 includes a multi-section structure along the height direction H, the angle a between the extending direction of the preset section 401 and the height direction H refers to the angle between the extending direction of the section closest to the positive tab 211 in the multi-section structure of the preset section 401. Please refer to FIG. 6 In yet another embodiment of the present embodiment, the preset section 401 includes a first section 4011 close to the positive tab 211 and a second section 4012 away from the positive tab 211, and the angle a between the extending direction of the preset section 401 and the height direction H refers to the angle between the extending direction of the first section 4011 and the height direction H, which is 0 degrees.

[0107] The secondary battery 1 also includes the above-mentioned first current collecting plate 31, which is located between the positive tab 211 and the end wall 11 of the shell 10 along the height direction H. The first current collecting plate 31 includes a pole connecting portion 311 and a positive tab connecting portion 312 connected together, the positive tab connecting portion 312 is electrically connected with the positive tab 211, and the pole connecting portion 311 is electrically connected with the pole 70.

[0108] As shown in FIG. 9 Specifically, the first insulating film 40 includes a substrate 41 and an adhesive layer 42 arranged on part of the surface of the substrate 41. Along the preset direction Q, the substrate 41 includes a first area 411 beyond the positive tab connecting portion 312 of the first current collecting plate 31 away from one side of the electrode assembly 20, and the first area 411 is not covered with the adhesive layer 42. The adhesive layer 42 covers part of the area on the side of the substrate 41 facing the wound structure 201, so as to fix the first insulating film 40 on the outer periphery of the wound structure 201. By arranging the first area 411 not covered with the adhesive layer 42, the first area 411 can be better arranged at an angle a of about 0 degrees with the height direction H, avoiding the first area 411 from being bonded to the first current collecting plate 31 during assembly due to the arrangement of the adhesive layer 42, and causing the formation of folds capable of storing electrolyte on the surface of the first current collecting plate 31, resulting in corrosion of the shell.

[0109] Preferably, along the preset direction Q, the substrate 41 comprises a second region 412 covered with the adhesive layer 42 and a third region 413 not covered with the adhesive layer 42, and the third region 413 coincides with the first region 411. However, the third region 413 can comprise the first region 411 in other embodiments, which can be adjusted according to actual needs.

[0110] The width of the substrate 41 along the height direction H is W, and the width of the second region 412 along the height direction H is w. The value of w / W is in the range of 0.12-0.8, for example, 0.12, 0.3, 0.46, 0.75 or 0.8, etc. By setting the value range of w / W, on the one hand, the width of the second region 412 covered with the adhesive layer 42 is avoided to be too small, and the function of fixing the first insulating film 40 to the outer periphery of the electrode assembly 20 is not played, on the other hand, the width of the second region 412 is avoided to be too large, and wrinkles are easily generated, and the electrolyte is easily stored, which causes the shell to be corroded.

[0111] Specifically, the value of w is in the range of 3mm-6mm, for example, 3mm, 4mm, 4.5mm, 5.8mm or 6mm, etc.; the value of W is in the range of 7mm-13mm, for example, 7mm, 8.5mm, 10mm, 11.8mm or 13mm, etc. By setting the value range of w, on the one hand, the width of the second region 412 covered with the adhesive layer 42 is avoided to be too small, and the function of fixing the first insulating film 40 to the outer periphery of the electrode assembly 20 is not played, on the other hand, the width of the second region 412 is avoided to be too large, and wrinkles are easily generated, and the electrolyte is easily stored, which causes the shell to be corroded. By setting the value range of W, on the one hand, the width of the substrate 41 is avoided to be too small, and the insulation function is not played; on the other hand, the width of the substrate 41 is avoided to be too large, which affects the overall size of the electrode assembly 20, thereby affecting the energy density of the battery.

[0112] The thickness of the substrate 41 is in the range of 40μm-65μm, for example, 40μm, 48μm, 52.5μm, 60.8μm or 65μm, etc. By setting the thickness range of the substrate 41, the thickness of the substrate 41 is avoided to be too thin, which causes it difficult to obtain the required electrical insulation and support strength; at the same time, the thickness of the substrate 41 is avoided to be too thick, which increases the thickness of the overall structure, and affects the energy density of the battery.

[0113] In the embodiment, the positive tab 211 is a flat tab, and the positive tab 211 is formed with a flat surface along the height direction H; along the preset direction Q, the distance between the first insulating film 40 and the flat surface is d, and the distance between the inner surface of the end wall 11 and the flat surface is D, and the value range of d / D is 0.1-0.99, for example, which can be 0.1, 0.3, 0.55, 0.8 or 0.99, etc. By setting the value range of d / D, on the one hand, the distance between the first insulating film 40 and the flat surface is too small, and the insulating effect cannot be achieved; on the other hand, the distance between the first insulating film 40 and the flat surface is too large, and unnecessary wrinkles are generated when the electrode assembly 20 and the shell 10 are assembled due to the contact with the shell 10. Specifically, the distance d between the first insulating film 40 and the flat surface is 1-5 mm, for example, which can be 1 mm, 2 mm, 2.5 mm, 3.8 mm or 5 mm, etc.

[0114] The secondary battery 1 further comprises a first insulating sealing member 50, which is located between the first current collector 31 and the end wall 11 along the height direction H. By setting the first insulating sealing member 50, the first current collector 31 and the end wall 11 are prevented from contacting and generating short circuit. Along the preset direction Q, the edge of the first insulating film 40 does not exceed the side of the first insulating sealing member 50 away from the electrode assembly 20, thereby preventing the first insulating film 40 from abutting against the end wall 11 and generating unnecessary wrinkles, causing the width direction of the first insulating film 40 to be stressed, so that the end wall 11 is contacted under the condition of assembly error, and at the same time, the end wall 11 is generally welded with the external adapter sheet, at this time, because the first insulating film 40 contacts the end wall 11, it is easy to shrink due to heat, affecting the safety performance of the battery.

[0115] Preferably, the first insulating film 40 is fixedly connected with the first insulating sealing member 50, thereby forming a connected insulating structure on the outer periphery of the first end of the electrode assembly 20, preventing the electrode assembly 20 from contacting the end wall 11 and the side wall 12 of the shell 10, and better playing the insulating role, and improving the safety of the battery under the working conditions such as vibration. Specifically, the first insulating film 40 and the first insulating sealing member 50 can be fixedly connected together by hot melting welding. Further, the first insulating film 40 is arranged around the outer periphery of the first insulating sealing member 50 to form a closed loop structure, thereby forming a whole closed insulating structure on the outer periphery of the first end of the electrode assembly 20, and better improving the insulating property and safety.

[0116] Further, the secondary battery 1 further comprises a second insulating film 60, which is arranged around the outer periphery of the winding structure 201 and is located between the first end and the second end along the height direction H. The orthographic projection of the first insulating film 40 and the second insulating film 60 along the radial direction R of the winding structure 201 does not overlap, i.e., the winding structure 201 partially covers the second insulating film 60 along the height direction H of the winding structure 201, and the second insulating film 60 and the first insulating film 40 are arranged staggeredly to avoid the stacking of the electrode assembly 20 along the radial direction R, which affects the diameter of the electrode assembly 20, thereby improving the energy density; and the second insulating film 60 also functions to fix the outer ring diaphragm 22 to prevent the diaphragm 22 from loosening.

[0117] Please refer to FIG. 8 The positive electrode sheet 21 comprises a positive electrode sheet starting end 217 and a positive electrode sheet ending end 218; the negative electrode sheet 23 comprises a negative electrode sheet starting end 237 and a negative electrode sheet ending end 238. The diaphragm 22 comprises a diaphragm starting end 221 and a diaphragm ending end 222. The second insulating film 60 comprises, but is not limited to, an ending tape for fixing the diaphragm ending end 222. That is, the second insulating film 60 can be an ending tape, or can be other insulating structures, such as a mylar film. Regardless of the structure of the second insulating film 60, the orthographic projection of the second insulating film 60 along the radial direction R of the winding structure 201 and the first insulating film 40 does not overlap.

[0118] The ratio of the thickness of the second insulating film 60 and the first insulating film 40 is 0.8-1.1, for example, which can be 0.8, 0.85, 0.95, 1.0 or 1.1, etc. As described above, the preset section 401 of the first insulating film 40 is arranged parallel or substantially parallel to the height direction H of the electrode assembly 20, compared to the preset section 401 of the first insulating film 40 being bonded to the first current collector 31, by setting the ratio of the thickness of the second insulating film 60 and the first insulating film 40, the diameter of the electrode assembly 20 can be made more uniform, thereby improving the energy density of the battery and the assembly is more accurate.

[0119] Preferably, the material of the substrate of the first insulating film 40 is PI (English full name: Polyimide, Chinese full name: Polyimide) or PET (English full name: Polyethylene terephthalate, Chinese full name: Polyethylene terephthalate). The name of the text is (polyimide). Since the first insulating film 40 is arranged at the position of the first end of the electrode assembly 20, which is the output end of the positive electrode, a higher temperature is generated when it is welded with the first current collector 31, and the PI material has higher heat resistance, thereby further improving its insulating function by virtue of its higher heat resistance. The adhesive layer of the first insulating film 40 contains polyacrylate.

[0120] The second insulating film 60 includes a substrate and an adhesive layer arranged on a part of the surface of the substrate. The material of the substrate of the second insulating film 60 is PI (Polyimide) or PET (Polyethyleneterephthalate). As described above, the main function of the second insulating film 60 is to fix the end of the diaphragm 222. Preferably, the material of the second insulating film 60 is PET, so that the second insulating film 60 can fix the end of the diaphragm 222 and save the manufacturing cost. The adhesive layer of the second insulating film 60 contains polyacrylate.

[0121] The peeling strength of the first insulating film 40 is 2-7 times the peeling strength of the second insulating film 60, for example, 2 times, 3.5 times, 4.5 times, 5.8 times or 7 times, etc., that is, the peeling strength of the first insulating film 40 is greater than the peeling strength of the second insulating film 60. Because the winding structure 201 will expand and contract during charging and discharging, if the adhesion of the second insulating film 60 is too high, it will restrict the expansion of the winding structure 201, which is not conducive to the capacity of the battery cell. On the other hand, if the adhesion of the second insulating film 60 is too low, it will not be able to fix the winding structure 201, and the winding structure 201 will be loose. For the first insulating film 40, it needs to fix the winding structure 201 and the positive tab 211 at the same time, and needs greater adhesion to ensure that the winding structure 201 and the positive tab 211 will not be loose, which is conducive to the first end of the winding structure 201 entering the shell. Moreover, if the adhesion of the first insulating film 40 is too low, it will fall off and cause insulation failure, which will cause the positive tab 211 to contact the shell 10 and short circuit. Therefore, by setting the peeling strength of the first insulating film 40 to be 2-7 times the peeling strength of the second insulating film 60, the capacity of the battery cell can be normally played. Specifically, the peeling strength of the first insulating film 40 is 2-7 N / cm, and the peeling strength of the second insulating film 60 is 1-4 N / cm.

[0122] It should be noted that the peeling strength of the first insulating film 40 and the peeling strength of the second insulating film 60 are tested by the test method of the adhesive tape peeling strength in the national standard GBT2792-2014.

[0123] The peeling strength test adopts Method 1 in the national standard GBT2792-2014: Test method for 180° peeling strength of adhesive tape and stainless steel, unit N / cm. If the insulating film has been made into a battery, the corresponding GBT2792-2014 standard can be tested according to the appropriate length of the insulating film in the battery, and it is not limited to the actual length of the insulating film defined in the GB.

[0124] Preferably, the second insulating film 60 is continuously arranged along the circumferential direction P of the winding structure 201 without overlapping, and a winding structure uncovered area not covered by the second insulating film 60 is formed at the outer periphery of the winding structure 201, and the orthographic projection of the overlapping portion of the first insulating film 40 along the circumferential direction P of the winding structure 201 in the height direction H at least partially falls in the winding structure uncovered area. By arranging the orthographic projection of the overlapping portion of the first insulating film 40 along the circumferential direction P of the winding structure 201 in the height direction H at least partially falls in the winding structure uncovered area, the overlapping of the first insulating film 40 along the circumferential direction P of the winding structure 201 and the second insulating film 60 in the radial direction R is avoided, the diameter of the battery cell is reduced, and the energy density of the battery is improved. In addition, the first insulating film 40 can support the winding structure uncovered area, and the difference in stress between the winding structure uncovered area and the winding structure covered area covered by the second insulating film 60 is reduced, and the situation of lithium precipitation after battery swelling is avoided.

[0125] Preferably, the second insulating film 60 and the first insulating film 40 are integrated, which can improve the production efficiency, reduce the diameter of the battery cell, and ensure the energy density of the battery.

[0126] In this embodiment, the secondary battery 1 is a cylindrical battery. The cylindrical battery has the advantages of high energy density, long cycle life, good safety performance, etc. In addition, when the secondary battery 1 is a cylindrical battery, the shell 10 of the cylindrical battery is a steel shell, so the shell 10 is negatively charged, and then the first insulating film 40 includes a preset section 401 extending beyond the outer surface of the positive electrode tab 211, and the angle α between the extension direction of the preset section 401 and the height direction H is in the range of 0-60 degrees, which can insulate the positive electrode tab 211 and the shell 10. In addition, because the cylindrical battery is a full-tab design, the first insulating film surrounds the outer periphery of the winding structure 201 near the first end for at least one turn. However, it is not limited to this, and in other embodiments, the secondary battery 1 can also be a square battery or other shaped battery.

[0127] The specific structure of the first insulating film 40 in this embodiment, in which the angle a between the extension direction of the portion (preset section 401) of the first insulating film 40 that exceeds the outer surface of the positive electrode tab 211 and the height direction H is in the range of 0-60 degrees, can be applied to a cylindrical battery, which can avoid the first insulating film 40 being adhered and attached to the first current collecting disc 31 to form a wrinkle capable of storing electrolyte, and the electrolyte in the wrinkle can penetrate into the shell 10 to cause corrosion of the shell 10, thereby improving the safety of the battery; and the first insulating film 40 includes the preset section 401 that exceeds the outer surface of the positive electrode tab 211, and the shell material of a large cylindrical battery (such as 4680 / 4695 / 46120 / 46150 cylindrical batteries) is steel, which can have higher strength, and the steel shell is often electrically connected to the negative electrode tab and is negatively charged, and the design of this embodiment can form electrical insulation between the positive electrode tab 211 and the shell 10, thereby increasing the safety of the battery.

[0128] The secondary battery 1 further includes a pole 70, the pole 70 is provided in the end wall 11 and is electrically connected to the positive electrode tab 211 through the first current collecting disc 31. The pole 70 is provided with a liquid injection through hole 71 along the height direction H. The liquid injection through hole 71 is provided corresponding to the first end of the electrode assembly 20, and the electrolyte flows into the shell 10 through the liquid injection through hole 71, and through the specific structure in which the angle a between the extension direction of the preset section 401 of the first insulating film 40 that is provided at the first end and the height direction H is in the range of 0-60 degrees, the electrolyte injected from the liquid injection through hole 71 can be effectively prevented from entering between the first insulating film 40 and the shell 10, thereby improving the electrolyte infiltration efficiency during positive electrode liquid injection.

[0129] The shell 10 is provided with an opening 14 at one end away from the end wall 11 of the accommodating cavity 13; the shell 10 further includes a crimping portion 15, the crimping portion 15 is formed at one end of the side wall 12 close to the opening 14 and is recessed towards the inside of the shell 10. The secondary battery 1 further includes a cover plate 80, a second insulating sealing member 90 and a second current collecting disc 32. The cover plate 80 is installed on the opening 14. The second insulating sealing member 90 is provided around the periphery of the cover plate 80 to insulate and seal the cover plate 80 and the shell 10. The second current collecting disc 32 is provided between the electrode assembly 20 and the cover plate 80 and is electrically connected to the shell 10, and the connecting piece of the second current collecting disc 32 is located on the side of the crimping portion 15 facing the electrode assembly 20 and is welded to the crimping portion 15. In this way, by arranging the connecting piece of the second current collecting disc 32 on the side of the crimping portion 15 facing the electrode assembly 20 and welded to the crimping portion 15, that is, the welding area of the second current collecting disc 32 to the negative electrode tab is located at a position closer to the electrode assembly 20 than the crimping portion 15, thereby preventing the influence of the crimping portion 15 on the welding area of the tab and the second current collecting disc 32, and thereby improving the welding strength of the negative electrode tab and the second current collecting disc 32.

[0130] The welding sequence of the first current collecting disc 31 and the second current collecting disc 32 of the secondary battery 1 in the embodiment is as follows: firstly, the first current collecting disc 31 is placed; then, the electrode assembly 20 is pressed on both sides of the positive electrode and the negative electrode (the pressing process can increase the contact between the current collecting disc and the electrode assembly 20, and avoid false welding); the first current collecting disc 31 is welded by adopting linear welding instead of spot welding, because the negative electrode tab is soft, and after being pressed twice, the second current collecting disc 32 and the electrode assembly 20 are relatively close, spot welding causes scalding of the diaphragm 22 due to heat concentration, linear welding can avoid scalding of the diaphragm 22, and cause short circuit between the positive electrode and the negative electrode; then, the second current collecting disc 32 is placed; the electrode assembly 20 is pressed on both sides of the positive electrode and the negative electrode again; finally, the second current collecting disc 32 is welded.

[0131] As FIG. 10 shown, the utility model also provides a battery pack 100, battery pack 100 includes above-mentioned secondary battery 1, in the embodiment of the utility model battery pack 100, battery pack 100 includes box 310, box cover 320 and multiple secondary batteries 1, multiple secondary batteries 1 are placed in box 310, and are connected in series or parallel with each other, or series and parallel hybrid, and the box cover 320 is sealed on the box 310 to protect multiple secondary batteries 1. It needs to be explained that battery pack 100 can also include battery pack 100 thermal management system, circuit board and other parts in addition to the secondary battery 1 of the utility model, and battery pack 100 can be a battery module or a battery pack, and can be an energy storage cabinet, etc., which will not be described one by one here.

[0132] As FIG. 11As shown, the utility model further provides an electronic device 1000, electronic device 1000 includes battery pack 100 described above. Working part 300 is electrically connected with battery pack 100 to obtain electric energy support. As an example, electronic device 1000 is vehicle, and vehicle can be fuel automobile, gas automobile or new energy automobile, and new energy automobile can be pure electric vehicle, hybrid vehicle or extended range vehicle, but is not limited. Working part 300 is vehicle body, and battery pack 100 is arranged at the bottom of vehicle body and provides electric energy support for the running of vehicle or the operation of electrical element in vehicle. However, in some other embodiments, electronic device 1000 can also be mobile phone, portable device, notebook computer, ship, spacecraft, electric toy and electric tool and the like. Spacecraft includes airplane, rocket, space shuttle and spacecraft and the like, and working part 300 can be unit component that can obtain the electric energy of battery pack 100 and make corresponding work, for example, fan blade rotating unit of fan, dust absorption working unit of dust collector and the like. Electric toy includes fixed or mobile electric toy, for example, game machine, electric car toy, electric ship toy and electric plane toy and the like, and electric tool includes metal cutting electric tool, grinding electric tool, assembly electric tool and railway electric tool, for example, electric drill, electric grinder, electric wrench, electric screwdriver, electric hammer, impact drill, concrete vibrator and electric planer and the like. The embodiment of the application does not specially limit the above-mentioned electronic device 1000.

[0133] Although the specific embodiments of the utility model are described above, those skilled in the art should understand that this is only an example, and the protection scope of the utility model is defined by the appended claims. Those skilled in the art can make various changes or modifications to these embodiments without departing from the principles and essence of the utility model, and these changes and modifications all fall within the protection scope of the utility model.

Claims

1. A secondary battery characterized by comprising: It includes: The shell includes an end wall and a side wall arranged around the end wall, and the end wall and the side wall are surrounded to form a containing cavity; The electrode assembly is located in the containing cavity, and the electrode assembly includes a positive electrode sheet, a separator and a negative electrode sheet stacked and wound to form a wound structure, the wound structure includes a first end provided with a positive electrode tab and a second end provided with a negative electrode tab in the height direction, and the second end is in a preset direction to the first end; The first insulating film is surrounded by at least one circle of the outer circumference of the wound structure close to the first end, and along the preset direction, the first insulating film includes a preset segment that exceeds the outer end face of the positive electrode tab, the preset segment extends towards the direction close to the end wall, and the angle between the extension direction of the preset segment and the height direction is in the range of 0-60 degrees.

2. The secondary battery according to claim 1, wherein The secondary battery also includes a first current collecting disc, which is located between the positive electrode tab and the end wall of the shell along the height direction, and the first current collecting disc includes a pole connecting part and a positive electrode tab connecting part connected together, the positive electrode tab connecting part is electrically connected with the positive electrode tab, and the pole connecting part is electrically connected with the pole; The first insulating film includes a substrate and a glue layer arranged on part of the surface of the substrate, and along the preset direction, the substrate includes a first area that exceeds the side of the positive electrode tab connecting part away from the electrode assembly, and the first area is not covered with the glue layer; and / or, The secondary battery also includes a first insulating seal, which is located between the first current collecting disc and the end wall along the height direction, and along the preset direction, the edge of the first insulating film does not exceed the side of the first insulating seal away from the electrode assembly.

3. The secondary battery according to claim 2, wherein Along the preset direction, the substrate includes a second area covered with the glue layer and a third area not covered with the glue layer, and the third area includes the first area, or the third area coincides with the first area; Suppose the width of the substrate along the height direction is W, and the width of the second area along the height direction is w, then the value range of w / W is 0.12-0.

8.

4. The secondary battery according to claim 2, wherein The first insulating film is fixedly connected with the first insulating seal.

5. The secondary battery according to claim 1, wherein The positive electrode tab is a flat tab, and the positive electrode tab forms a flat surface along the height direction; along the preset direction, suppose the distance between the first insulating film and the flat surface is d, and the distance between the inner surface of the end wall and the flat surface is D, then the value range of d / D is 0.1-0.

99.

6. The secondary battery according to claim 1, wherein The secondary battery also includes a second insulating film, which surrounds the outer circumference of the wound structure and is located between the first end and the second end along the height direction; Along the radial direction of the wound structure, the orthographic projection of the first insulating film and the second insulating film does not overlap; and / or, The material of the substrate of the second insulating film is PI or PET; and / or, The thickness ratio of the second insulating film to the first insulating film is 0.8-1.1; and / or, The peeling strength of the first insulating film is 2-7 times the peeling strength of the second insulating film.

7. The secondary battery according to claim 6, wherein the positive electrode is a lithium ion secondary electrode. The second insulating film is continuously arranged along the circumference of the winding structure without overlapping, and a winding structure uncovered area, which is not covered by the second insulating film, is formed at the outer circumference of the winding structure. The first insulating film is arranged along the overlapping part of the circumference of the winding structure, and the orthographic projection of the first insulating film along the height direction at least partially falls within the winding structure uncovered area.

8. The secondary battery according to any one of claims 1 to 7, wherein The secondary battery is a cylindrical battery, and the secondary battery further comprises: a pole post, which is arranged through the end wall and is electrically connected to the positive electrode tab through the first current collector; the pole post is provided with a liquid injection through hole along the height direction; and / or, the accommodation cavity of the shell is provided with an opening at one end away from the end wall; the shell further comprises a crimping part, which is formed at one end of the side wall close to the opening and is recessed towards the inside of the shell; the secondary battery further comprises: a cover plate, which is mounted on the opening; a second insulating sealing member, which is arranged around the periphery of the cover plate to insulate and seal the cover plate and the shell; a second current collector, which is arranged between the electrode assembly and the cover plate and is electrically connected to the shell; the connecting piece of the second current collector is located on the side of the crimping part facing the electrode assembly and is welded to the crimping part; and / or, the material of the base material of the first insulating film is PI.

9. A battery pack characterized by comprising: The secondary battery of any one of claims 1 to 8.

10. An electronic device, comprising: The battery pack of claim 9.

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