Cylindrical battery

Abstract

The present invention relates to the technical field of batteries, and discloses a cylindrical battery, which comprises: a shell, the bottom of which is provided with a liquid injection hole, and the area of the shell surrounding the liquid injection hole protrudes towards the interior of the shell to form a step part; the battery cell is arranged in the shell, and the battery cell comprises two end surfaces and a peripheral surface which are oppositely arranged; the step part is used for partially supporting the battery cell; the insulating film covers the peripheral surface of the battery cell, and the insulating film extends to at least one end surface of the battery cell; the area where the insulating film extends to the end face forms an extending edge which forms a continuous ring shape on the end face. And the insulating film is at least partially overlapped in the extending edge region to form an overlapped part. According to the cylindrical battery provided by the invention, the overlapping part can be cushioned at the gap between the battery cell and the shell to play a role in supporting the battery cell, so that the stability of the battery cell is improved, the battery cell is prevented from touching the bottom wall of the shell, and the damage to the pole piece is prevented.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and in particular to a cylindrical battery. Background Art

[0002] The cylindrical battery includes a shell and a cell disposed in the shell. A liquid injection hole is disposed at the bottom of the shell, and a step portion is disposed in the shell around the liquid injection hole toward the cell. After the cell is loaded into the shell, the cell is suspended in the area outside the step portion due to the support of the step portion on the bottom of the cell, so that the cell is supported by a small area, which makes it easy for the pole piece to be locally stressed and easily damaged under bumpy conditions. Summary of the invention

[0003] In view of this, the present invention provides a cylindrical battery to solve the problem that when the step at the bottom of the shell supports the battery cell, the battery cell is easily subjected to local stress.

[0004] The present invention provides a cylindrical battery, comprising:

[0005] The shell has a liquid injection hole at the bottom, and the area of ​​the shell surrounding the liquid injection hole protrudes toward the inside of the shell to form a step portion;

[0006] The battery core is arranged in the shell, and the battery core comprises two oppositely arranged end surfaces and a peripheral surface; the step portion is used to partially support the battery core;

[0007] An insulating film is coated on the circumference of the battery cell, and the insulating film extends to at least one end face of the battery cell; the insulating film extends to the region of the end face to form an extended edge, and the extended edge forms a continuous ring on the end face; and the insulating film is at least partially overlapped in the extended edge region to form an overlapping portion;

[0008] The radial length of the extended edge is L, and the radial diameter of the battery cell is D0, which satisfies: 0.03≤L / D0≤0.25.

[0009] Beneficial effect: The cylindrical battery provided by the embodiment of the present invention has an insulating film coated on the circumferential surface of the battery cell, and the insulating film extends from the circumferential surface of the battery cell to at least one end face of the battery cell, and is folded on the end face, and the insulating film forms an extended edge in the end face area. Since the portion of the insulating film covering the circumferential surface and the portion folded to the end face are integrally arranged, when the circumferential surface covers the end face, the extended edge is continuously arranged around the circumference of the end face, which will cause wrinkles in the extended edge area of ​​the insulating film, that is, the insulating film is at least partially overlapped in the extended edge area to form an overlapping portion. Along the axial direction, the thickness of the overlapping portion is greater than the thickness of the insulating film, so that the overlapping portion can be arranged in the gap between the battery cell and the shell, which plays a role in supporting the battery cell, improving the stability of the battery cell, avoiding the battery cell from hitting the bottom wall of the shell, and preventing damage to the pole piece. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0011] Figure 1 It is a schematic diagram of the disassembled state of the cylindrical battery of the present invention;

[0012] Figure 2 It is a cross-sectional schematic diagram of a cylindrical battery of the present invention in a disassembled state;

[0013] Figure 3 It is a cross-sectional schematic diagram of a cylindrical battery of the present invention;

[0014] Figure 4 for Figure 3 A partial enlarged view of

[0015] Figure 5 It is a schematic diagram of the dimensions of the cylindrical battery of the present invention;

[0016] Figure 6 It is a cross-sectional view of the present invention in which the housing and the battery core are in a separated state;

[0017] Figure 7 It is a cross-sectional view of the internal structure of the battery cell of the present invention.

[0018] Description of reference numerals:

[0019] 1. Shell; 11. Liquid injection hole; 12. Step portion;

[0020] 2. Battery cell; 21. End surface; 22. Core hole; 23. Diaphragm; 24. Pole sheet; 241. Negative electrode sheet; 242. Positive electrode sheet; 25. Peripheral surface;

[0021] 3. Insulating film; 31. Extended edge; 32. Overlapping portion; 4. Cover plate; 5. Sealing plug; 6. Sealing cover. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0023] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0024] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0025] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0026] Combine the following Figures 1 to 7 , describing an embodiment of the present invention.

[0027] According to an embodiment of the present invention, there is provided a cylindrical battery, comprising:

[0028] The shell 1 has a liquid injection hole 11 at the bottom, and the area of ​​the shell 1 surrounding the liquid injection hole 11 protrudes toward the inside of the shell 1 to form a step portion 12;

[0029] The battery core 2 is disposed in the housing 1, and includes two oppositely disposed end surfaces 21 and a peripheral surface 25; the step portion 12 is used to partially support the battery core 2;

[0030] The insulating film 3 is coated on the peripheral surface 25 of the battery cell 2, and the insulating film 3 extends to at least one end surface 21 of the battery cell 2; the insulating film 3 extends to the region of the end surface 21 to form an extended edge 31, and the extended edge 31 forms a continuous ring on the end surface 21; and the insulating film 3 is at least partially overlapped in the region of the extended edge 31 to form an overlapping portion 32;

[0031] The length of the extended edge 31 in the radial direction is L, and the diameter of the battery cell 2 in the radial direction is D0, which satisfies: 0.03≤L / D0≤0.25.

[0032] In this embodiment, the cylindrical battery further includes a cover plate 4, which is disposed on the opposite side of the bottom of the housing 1 and is used to block the opening of the housing 1. The battery cell 2 is installed in the housing 1 through the opening of the housing 1.

[0033] The bottom of the housing 1 is provided with a liquid injection hole 11. After the liquid injection is completed, the liquid injection hole 11 is sealed with a sealing plug 5. The bottom of the housing 1 refers to the side of the bottom end along the height direction when the cylindrical battery is placed. The liquid injection hole 11 is a through hole arranged at the bottom of the housing 1, and is connected to the inside of the housing.

[0034] The injection hole 11 can be formed by stamping to form a step portion 12 protruding toward the inside of the shell; correspondingly, a groove is formed outside the shell 1, and the position of the groove can be used to accommodate the sealing cover 6.

[0035] In this embodiment, the battery cell 2 is wound, and a winding hole 22 is formed at the winding center of the battery cell 2. By aligning the injection hole 11 with the winding hole 22, the injection of the cylindrical battery can be facilitated and the injection efficiency can be improved.

[0036] The area of ​​the shell 1 surrounding the injection hole 11 protrudes toward the inside of the shell 1 to form a step portion 12. After the first injection, the sealing plug 5 will be inserted into the injection hole 11 to achieve the sealing of the injection hole 11, and the sealing plug 5 will be taken out during the second injection. In order to ensure the sealing effect of the injection hole 11, a good connection can be achieved by welding the sealing cover 6 to the bottom of the shell 1. The sealing cover 6 and the injection hole 11 are welded together. If a depression is not set at the injection hole 11, the sealing cover 6 will protrude from the bottom of the shell 1, resulting in poor flatness of the bottom surface of the shell 1. At this time, the depression set at the bottom of the shell 1 is reflected in the inside of the shell 1 as the step portion 12. Therefore, the area of ​​the shell 1 surrounding the injection hole 11 protrudes toward the inside of the shell 1, that is, the step portion 12 is formed.

[0037] However, due to the presence of the step portion 12, after the battery cell 2 is installed in the shell 1, the battery cell 2 will be raised, and because the area of ​​the step portion 12 is small, only the middle area of ​​the battery cell 2 in the radial direction is in contact with the step portion 12, resulting in the battery cell 2 being suspended in the area outside the step portion 12, making the area of ​​the bottom of the battery cell 2 supported by force small, causing the battery cell 2 to easily tilt. Under bumpy conditions, the tilt of the battery cell 2 will cause the battery cell 2 to contact the shell wall, which is likely to cause the pole piece to be locally stressed, thereby causing damage to the pole piece. In addition, the smaller the area of ​​the step portion 12, the weaker the support for the battery cell 2, which is likely to cause insufficient support for the battery cell 2, resulting in the battery cell 2 contacting or bumping against the bottom wall of the shell 1.

[0038] If a bottom support plate is added at the bottom of the battery cell 2, the weight of the battery will increase, resulting in increased cost and complicated process, etc. In this embodiment, the insulating film 3 coated on the outer surface of the battery cell 2 is used to form wrinkles, i.e., overlapping portions 32, when the insulating film 3 is coated on the battery cell, so that the overlapping portions 32 are filled between the battery cell 2 and the housing 1, thereby supporting the battery cell 2 and reducing the risk of the battery cell tilting.

[0039] The insulating film 3 is coated on the circumferential surface 25 of the battery cell 2, and the insulating film 3 extends to at least one end face 21 of the battery cell 2; the area where the insulating film 3 extends to the end face 21 forms an extension edge 31, and the extension edge 31 forms a continuous ring on the end face 21; the continuous ring means that the extension edge 31 is continuous on the end face 21 of the insulating film 3, and there is no place for cutting on the ring. For ease of understanding, the relevant technology is introduced here for comparison. In the relevant technology, when coating the insulating film, the portion of the insulating film folded to the end face is generally cut to avoid the formation of wrinkles when the insulating film is coated. The embodiment of the present invention is just the opposite. When the insulating film 3 extends from the circumferential surface 25 to the end face 21, the cutting process is not performed, so that the insulating film 3 is at least partially overlapped in the extension edge 31 area to form an overlapping portion 32.

[0040] In the cylindrical battery provided by the embodiment of the present invention, the insulating film 3 is coated on the circumferential surface 25 of the battery cell 2, and the insulating film 3 extends from the circumferential surface 25 of the battery cell 2 to at least one end surface 21 of the battery cell 2, and is folded at the end surface 21, and the insulating film 3 forms an extended edge 31 in the region of the end surface 21. Since the portion of the insulating film 3 covering the circumferential surface and the portion folded to the end surface 21 are integrally arranged, when the circumferential surface is coated on the end surface 21, since the extended edge 31 is continuously arranged around the circumference of the end surface 21, wrinkles will appear in the region of the extended edge 31 of the insulating film 3, that is, the insulating film 3 is at least partially overlapped in the region of the extended edge 31 to form an overlapping portion 32. Along the axial direction, the thickness of the overlapping portion 32 is greater than the thickness of the insulating film 3, so that the overlapping portion 32 can be arranged in the gap between the battery cell 2 and the shell 1, playing a role in supporting the battery cell 2, improving the stability of the battery cell 2, and preventing the battery cell 2 from hitting the bottom wall of the shell 1, thereby preventing damage to the pole piece. It should be further explained that the overlapping portion 32 is arranged in the gap between the battery cell 2 and the shell 1, which can be divided into two specific situations. One is that the overlapping portion 32 abuts against the bottom wall of the shell 1, and the other is that there is a certain gap between the overlapping portion 32 and the bottom wall of the shell 1. Due to tolerance and other reasons, there may be a situation where there is no abutment. In the first case, the overlapping portion 32 plays a role in supporting the battery cell 2; in the second case, the overlapping portion 32 is used to reduce the distance between the battery cell and the shell, so that the overlapping portion 32 is the lowest point, which can reduce the probability of the battery cell 2 directly contacting the shell wall after tilting, thereby protecting the battery cell and reducing the risk of pole piece damage.

[0041] The radial length of the extended edge 31 is L, and the radial length L of the extended edge 31 cannot be too small or too large; if the radial length L of the extended edge 31 is too small, the area of ​​the overlapping portion 32 will be small, which is not conducive to supporting the battery cell 2; if the radial length L of the extended edge 31 is too large, that is, the longer the length of the extended edge 31 covering the end face 21, the larger the overlapping area between the extended edge 31 and the bottom wall of the shell 1. Since the insulating film 3 is a continuous ring and extends from the circumference to the end face in one piece, it means that the entire end face covered by the insulating film 3 is blocked, which easily leads to a decrease in the electrolyte infiltration rate. After the electrolyte is injected, a part of the electrolyte will be stored between the battery cell and the shell for subsequent rehydration. If the insulating film is too long, it will affect the subsequent infiltration of the electrolyte.

[0042] Furthermore, the present embodiment defines the upper and lower limits of L / D0. On the one hand, it can avoid the ratio being too small, resulting in a small area of ​​the overlapping portion 32, which cannot play the role of filling the gap between the battery cell and the shell, and avoid the battery cell 2 from tilting and damaging the pole piece; on the other hand, the L / D0 ratio cannot be too large. Since the gap between the battery cell 2 and the shell 1 can be used to store electrolyte, if the L / D0 ratio is too large, the electrolyte storage space will become smaller. If the ratio is too large, the size of the insulating film covering the battery cell end face 21 is too large, which will affect the subsequent infiltration of the electrolyte into the battery cell, making it difficult to replenish the electrolyte to the battery cell, resulting in the subsequent battery cycle performance degradation; avoid the internal gas storage space being small during thermal runaway, which causes the explosion-proof valve to open prematurely.

[0043] In this embodiment, the material of the insulating film 3 can be PP or the like.

[0044] In some embodiments, in combination Figure 6 As shown, along the axial direction, the distance between the surface of the step portion 12 close to the battery cell 2 and the bottom surface of the housing 1 is h, the number of layers of the overlapping portion 32 is n, and the thickness of the insulating film 3 is d, which satisfies:

[0045] 0.8≤h / (n·d)≤10.

[0046] The sealing plug 5 is made of an elastic material, such as a rubber plug. After the first injection is completed, the sealing plug 5 is installed in the injection hole 11 through interference fit to achieve sealing of the injection hole 11. During the second injection, the sealing plug 5 is taken out, and the sealing cover 6 is welded to the bottom of the housing 1. The sealing cover 6 can be made of a metal material and is made of the same material as the housing 1, such as steel or aluminum. By welding the sealing cover 6 to the bottom of the housing 1, a good connection can be achieved.

[0047] The number of layers of the overlapping portion 32 is n. Since the overlapping portion 32 is formed by overlapping continuous insulating films 3, each overlapping portion 32 is specifically formed by two layers of insulating films 3. The larger n·d is, the thicker the overlapping portion 32 is.

[0048] The larger h is, the larger the distance between the battery cell 2 and the bottom surface of the shell 1 is, that is, the thicker the overlapping portion 32 to be filled is. By controlling the range of h / (n·d), it is possible to ensure that the distance to be filled and the total thickness of the overlapping portion 32 used for filling are in a relatively balanced state, so as to better meet the filling effect, so that the overlapping portion 32 is filled between the battery cell 2 and the shell 1, thereby supporting the battery cell 2, reducing the risk of the battery cell tilting, and avoiding damage to the electrode piece.

[0049] In some embodiments, the value range of h is: 0.4 mm ≤ h ≤ 1.5 mm;

[0050] The value range of n is: 3≤n≤6;

[0051] The value range of d is: 0.03mm≤d≤0.18mm.

[0052] By limiting the lower limit of h, it is possible to ensure that sufficient assembly space is reserved for the sealing cover 6, avoid the sealing cover 6 protruding from the bottom of the shell 1, and prevent the sealing cover 6 from interfering with the assembly of the cylindrical battery.

[0053] By limiting the upper limit of h, it is possible to avoid the battery cell 2 being supported too high, avoid the battery cell being more easily tilted, and reduce the contact between the battery cell 2 and the housing 1 .

[0054] By limiting the value range of n, it is possible to avoid the situation where the overlapping portion 32 is difficult to fold when the number of layers n is too large, thereby reducing the difficulty of processing.

[0055] In this embodiment, the value of h can specifically be 0.4 mm, 0.5 mm, 0.6 mm, 0.8 mm, 1 mm, 1.1 mm, 1.2 mm, 1.4 mm, 1.5 mm, etc.

[0056] In this embodiment, the value of n can specifically be 3, 4, 5 or 6.

[0057] In this embodiment, the value of d can be specifically 0.03 mm or 0.05 mm or 0.06 mm or 0.08 mm or 0.1 mm or 0.12 mm or 0.15 mm or 0.17 mm or 0.18 mm, etc.

[0058] In some embodiments, in combination Figure 7 As shown, the battery cell 2 includes stacked pole pieces 24, which specifically include a negative pole piece 241 and a positive pole piece 242. The battery cell 2 also includes a separator 23 spaced between adjacent negative pole pieces 241 and positive pole pieces 242.

[0059] Along the axial direction, the length of the separator 23 beyond the negative electrode sheet 241 is b, which satisfies:

[0060] 0.3mm≤b≤2.5mm.

[0061] It is worth noting that the separator 23 is arranged between the positive electrode sheet 242 and the negative electrode sheet 241, and the positive electrode sheet 242, the negative electrode sheet 241 and the separator 23 are wound or stacked to form the battery cell 2; the positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer, and the negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer. There is no special restriction on the positive electrode current collector, as long as it has conductivity and does not cause adverse chemical changes in the battery, and can use, for example: stainless steel, aluminum, nickel, titanium, fired carbon, or aluminum or stainless steel with a surface treatment of carbon, nickel, titanium, silver, etc.; the negative electrode current collector can be copper, stainless steel, nickel, titanium, etc., and a composite current collector can also be used. The composite current collector refers to a polymer layer in the middle, and metal layers are arranged on the opposite sides of the polymer layer. The metal layer can be made of copper, stainless steel, nickel, titanium, etc.; in a specific embodiment, the positive electrode current collector can be aluminum, and the negative electrode current collector can be copper. The positive electrode active material layer includes positive electrode active materials, which include nickel-cobalt-manganese ternary materials, lithium iron phosphate materials, lithium manganese iron phosphate materials, etc.; the negative electrode active material layer includes negative electrode active materials, which include artificial graphite, natural graphite, silicon-based materials, etc.

[0062] The length b of the separator 23 beyond the negative electrode sheet 241 is called Overhang (negative electrode excess design), and its purpose is to ensure the insulation effect between the battery cell and the shell.

[0063] By defining the lower limit of b, it is possible to ensure that the length of the diaphragm 23 exceeds the negative electrode sheet 241. Even if the battery cell tilts, there is enough diaphragm to contact the shell, reducing the risk of damage to the electrode sheet. By defining the upper limit of b, it is prevented that the diaphragm 23 exceeds the negative electrode sheet 241 too much and affects the injection. If the diaphragm 23 exceeds too much, it is easy to be drawn out by negative pressure when the battery is injected, so that the diaphragm 23 blocks the injection hole and affects the injection.

[0064] Additionally, along the axial direction, the negative electrode sheet 241 is arranged beyond the positive electrode sheet 242. The purpose of the portion where the negative electrode sheet 241 exceeds the positive electrode sheet 242 is to reduce lithium deposition and ensure that after the positive electrode sheet 242 is de-lithiated, the negative electrode sheet 241 has sufficient lithium embedding space. Therefore, the negative electrode size generally exceeds the positive electrode size.

[0065] In this embodiment, the value of b can specifically be 0.3mm or 0.4mm or 0.5mm or 0.6mm or 0.8mm or 1mm or 1.1mm or 1.2mm or 1.4mm or 1.5mm or 1.8mm or 2mm or 2.2mm or 2.5mm, etc.

[0066] In some embodiments, the insulating film 3 is connected to the diaphragm 23 , and the thickness of the insulating film 3 is d, satisfying: 0.05 mm≤d≤0.18 mm.

[0067] Since the diaphragm 23 is relatively soft, when the insulating film 3 is bonded to the diaphragm 23 , the insulating film 3 may absorb a portion of its thickness due to the shrinkage of the diaphragm 23 , for example, causing the insulating film 3 to sink toward the battery cell side, so the thickness of the insulating film 3 needs to be set larger.

[0068] In this embodiment, the length b of the diaphragm 23 extending beyond the negative electrode sheet 241 cannot be too small. Since the diaphragm material is relatively soft and has a certain degree of shrinkage, when b is too small, the thickness of the insulating film 3 will be partially eaten away due to the shrinkage of the diaphragm 23, and there is a risk of insulation failure. At the same time, the length b of the diaphragm 23 extending beyond the negative electrode sheet 241 cannot be too large. Since the insulating film 3 is connected to the diaphragm 23, when b is too large, the superimposed effect of the diaphragm 23 and the insulating film 3 will make it more difficult for the bottom electrolyte to infiltrate.

[0069] In this embodiment, the value of d can specifically be 0.05 mm, 0.06 mm, 0.08 mm, 0.1 mm, 0.12 mm, 0.15 mm, 0.17 mm, 0.18 mm, etc.

[0070] In some embodiments, a groove is formed at the bottom of the housing 1, and the projection of the injection hole 11 along the axial direction is located in the groove;

[0071] The cylindrical battery further includes a sealing cover 6 , which is disposed in the groove and does not protrude from the bottom surface of the housing 1 along the axial direction.

[0072] Since the sealing cover 6 needs to be arranged not to protrude from the bottom surface of the housing 1 to avoid poor flatness of the bottom surface of the housing 1, a step portion needs to be formed inside the housing 1 to leave space for the formation of the groove.

[0073] In some embodiments, a winding core hole 22 is formed at the winding center of the battery core 2, and the diameter of the winding core hole 22 along the radial direction is D1, satisfying:

[0074] 20≤D1 / (L / D0)≤160.

[0075] The electrolyte is mainly injected into the battery through the core hole. When the diameter of the core hole 22 is large, more electrolyte will be stored in the core hole 22. At this time, the electrolyte free in the shell will be relatively small. The electrolyte stored in the core hole 22 can meet the wetting requirements of the battery cell 2. At this time, the effect of the electrolyte free in the shell on the wetting of the battery cell 2 will be reduced, that is, the radial length L of the extended edge 31 of the insulating film 3 will have a lower effect on the wetting of the battery cell 2. At this time, the radial length L of the extended edge 31 can be made longer. On the contrary, when the diameter of the core hole 22 is small, the capacity of the electrolyte stored in the core hole 22 will be reduced, and the electrolyte free in the shell will be relatively more. The wetting of the battery cell 2 depends more on the electrolyte free in the shell. At this time, the radial length L of the extended edge 31 needs to be made shorter to avoid affecting the wetting effect of the electrolyte in the shell on the battery cell 2.

[0076] In some embodiments, the length L of the extended edge 31 along the radial direction satisfies: 2 mm ≤ L ≤ 10 mm.

[0077] As an option, the length L of the extended edge 31 along the radial direction may be 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm or 10 mm.

[0078] In some embodiments, the battery cell 2 includes a battery cell body and a current collecting component. The current collecting component is arranged on one side of the battery cell body away from the injection hole 11. The insulating film 3 also extends to the other end surface of the battery cell 2 close to the current collecting component and partially covers the current collecting component.

[0079] In this embodiment, the shell 1 is connected to the negative electrode of the battery, and the shell 1 is charged. By making the insulating film 3 at least partially cover the current collecting component, a short circuit between the side of the battery cell 2 where the current collecting component is set and the shell 1 can be avoided, thereby improving safety.

[0080] In some embodiments, the cylindrical battery further includes a pole, which is disposed on the shell 1 , and the current collecting component includes a positive current collecting disc and a negative current collecting disc, one of the positive current collecting disc or the negative current collecting disc is electrically connected to the shell 1 ; the other is electrically connected to the pole.

[0081] In this embodiment, the shell 1 serves as one of the electrode output terminals, and the current collecting component may have opposite electrical properties to the shell 1. By making the insulating film 3 at least partially cover the current collecting component, the insulation performance between the current collecting component with opposite electrical properties and the shell can be increased, thereby avoiding short circuits and improving safety.

[0082] In some embodiments, L further satisfies: 2mm≤L≤8mm.

[0083] Because the insulating film 3 at least partially covers the current collecting member, at this time, the radial length L of the extended edge 31 cannot be too large. If it is too large, it will cause too much overlap between the insulating film 3 and the battery cell. Since the current collecting member bears the overcurrent function, it will generate heat. When the insulating film 3 and the battery cell overlap too much, it is easy to affect the heat dissipation of the current collecting member. Therefore, it is necessary to further limit the range of L.

[0084] In this embodiment, the current collecting member may also be a tab.

[0085] In this embodiment, the value of L can specifically be 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, etc.

[0086] In some embodiments, a plurality of overlapping portions 32 are provided along the circumference of the cylindrical battery.

[0087] When a plurality of overlapping portions 32 are provided along the circumference of the cylindrical battery, a plurality of fulcrums can be formed along the circumference of the cylindrical battery to prevent the battery from tilting from multiple angles.

[0088] Obviously, the above embodiments are only examples for clear explanation, and are not intended to limit the implementation methods. Although the embodiments of the present invention are described in conjunction with the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations all fall within the scope defined by the present invention.

Claims

1. A cylindrical battery, characterized in that: include: The shell (1) has a liquid injection hole (11) at the bottom, and a region of the shell (1) surrounding the liquid injection hole (11) protrudes toward the inside of the shell (1) to form a step portion (12); A battery core (2) is arranged in the housing (1), the battery core (2) comprising two oppositely arranged end surfaces (21) and a peripheral surface (25); the step portion (12) is used to partially support the battery core (2); An insulating film (3) is coated on the circumferential surface (25) of the battery cell (2), and the insulating film (3) extends to at least one end surface (21) of the battery cell (2); the insulating film (3) extends to the region of the end surface (21) to form an extended edge (31), and the extended edge (31) forms a continuous ring on the end surface (21); and the insulating film (3) is at least partially overlapped in the region of the extended edge (31) to form an overlapping portion (32); The radial length of the extended edge (31) is L, the radial diameter of the battery core (2) is D0, and the following relationship is satisfied: 0.03≤L / D0≤0.25; The battery cell (2) comprises a negative electrode sheet (241) and a positive electrode sheet (242) which are stacked, and a separator (23) which is spaced between adjacent negative electrode sheets (241) and positive electrode sheets (242); Along the axial direction, the length of the separator (23) beyond the negative electrode sheet (241) is b, satisfying: 0.3 mm ≤ b ≤ 2.5 mm; The bottom of the housing (1) is formed with a groove, and the projection of the liquid injection hole (11) along the axial direction is located in the groove.

2. The cylindrical battery according to claim 1, characterized in that: The insulating film (3) is connected to the diaphragm (23), and the thickness of the insulating film (3) is d, satisfying: 0.05 mm ≤ d ≤ 0.18 mm.

3. The cylindrical battery according to claim 1, characterized in that: The cylindrical battery further comprises: a sealing cover (6), wherein the sealing cover (6) is arranged in the groove, and the sealing cover (6) does not protrude from the bottom surface of the housing (1) along the axial direction.

4. The cylindrical battery according to claim 1, characterized in that: The battery core (2) comprises a winding core hole (22), and the diameter of the winding core hole (22) along the radial direction is D1, satisfying: 20≤D1 / (L / D0)≤160.

5. The cylindrical battery according to claim 1, characterized in that: The length L of the extended edge (31) along the radial direction satisfies: 2mm≤L≤10mm.

6. The cylindrical battery according to claim 1, characterized in that: The battery cell (2) comprises a battery cell body and a current collecting component, wherein the current collecting component is arranged on a side of the battery cell body away from the injection hole (11), and the insulating film (3) also extends to the other end surface of the battery cell (2) close to the current collecting component and partially covers the current collecting component.

7. The cylindrical battery according to claim 6, characterized in that: The cylindrical battery further comprises a pole, which is arranged on the shell (1); the current collecting component comprises a positive current collecting disc and a negative current collecting disc; one of the positive current collecting disc or the negative current collecting disc is electrically connected to the shell (1); and the other is electrically connected to the pole.

8. The cylindrical battery according to claim 6 or 7, characterized in that: Meets: 2mm≤L≤8mm.

9. The cylindrical battery according to claim 1, characterized in that: A plurality of overlapping portions (32) are arranged along the circumference of the cylindrical battery.

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