Cylindrical battery cell

Abstract

The utility model provides a cylindrical battery cell. The cylindrical battery cell comprises a shell, an electrode assembly and a core rod, the electrode assembly is installed in the shell in a sealed mode and provided with a center hole. The core rod is at least partially arranged in the center hole, and the side wall of the core rod at least partially abuts against the hole wall of the center hole; wherein the core rod comprises a sealing cavity for accommodating electrolyte and a weak part, the sealing cavity comprises a cavity wall, the weak part is arranged on the cavity wall, and the weak part is broken when the internal pressure of the shell is greater than a set threshold value, so that the electrolyte in the sealing cavity is in contact with the electrode assembly. The cylindrical battery cell provided by the utility model can improve the technical problem that the cycle performance and the service life of the cylindrical battery cell are reduced due to the fact that the cylindrical battery cell is easy to lack of liquid in the recycling process.

Description

Technical Field

[0001] The utility model relates to the technical field of batteries, in particular to a cylindrical battery core. Background Art

[0002] With the high temperature and a series of chemical reactions generated during the use of cylindrical batteries, the electrolyte inside the cylindrical batteries often suffers from large losses after a period of use, especially in the later stages of the cycle, when the lack of electrolyte inside the cylindrical batteries is particularly obvious. Cylindrical batteries are prone to lithium precipitation when they are running in a state of lack of electrolyte for a long time, which affects the cycle process of the cylindrical batteries, and further causes a significant decrease in the reversible capacity of the cylindrical batteries, reducing the performance and service life of the cylindrical batteries.

[0003] In order to reduce the impact of the lack of liquid in cylindrical cells on the service life of cylindrical cells, high-porosity diaphragms and thick base films are usually used to increase the liquid retention capacity of the cells to extend the cycle life of the cylindrical cells. However, this method will significantly reduce the volume energy density of the cylindrical cells. Utility Model Content

[0004] In view of the above shortcomings of the prior art, the utility model provides a cylindrical battery cell to improve the technical problem that the cylindrical battery cell is prone to lack of liquid during recycling, resulting in reduced cycle performance and service life of the cylindrical battery cell.

[0005] To achieve the above-mentioned purpose and other related purposes, the utility model provides a cylindrical battery cell, which includes: a shell, an electrode assembly and a core rod; the electrode assembly is sealed and installed in the shell, and the electrode assembly has a center hole; the core rod is at least partially arranged in the center hole, and the side wall of the core rod is at least partially abutted against the hole wall of the center hole; wherein, the core rod includes a sealed cavity for accommodating electrolyte and a weak portion, the sealed cavity includes a cavity wall, the weak portion is arranged in the cavity wall, and the weak portion ruptures when the internal pressure of the shell is greater than a set threshold value, so that the electrolyte in the sealed cavity contacts with the electrode assembly.

[0006] In an example of the cylindrical battery cell of the present invention, the weak portion is arranged facing the hole wall of the central hole.

[0007] In an example of the cylindrical battery cell of the present invention, the opening pressure of the weak portion is 0.35-1.55 MPa.

[0008] In an example of the cylindrical battery cell of the present invention, the core rod includes a plurality of sealed cavities, and the plurality of sealed cavities are arranged in sequence along the height direction of the core rod.

[0009] In an example of the cylindrical battery cell of the present invention, a plurality of weak parts are provided, a cavity wall of each sealed cavity is provided with a plurality of weak parts, and the opening pressures of the weak parts corresponding to at least two sealed cavities are different.

[0010] In an example of the cylindrical battery cell of the present invention, the weak portion includes a notch.

[0011] In an example of a cylindrical battery cell of the utility model, the core rod includes a first weak portion, a second weak portion and a third weak portion, and the first weak portion, the second weak portion and the third weak portion are respectively arranged on the cavity walls of different sealed cavities; the opening pressure of the first weak portion is 0.35Mpa~0.55Mpa, the opening pressure of the second weak portion is 0.55Mpa~0.75Mpa, and the opening pressure of the third weak portion is 0.75Mpa-1.55Mpa.

[0012] In an example of a cylindrical battery cell of the present invention, the cavity wall is made of aluminum, the first weak portion includes a first notch, and the residual thickness of the cavity wall at the first notch is 20μm to 39.5μm; the second weak portion includes a second notch, and the residual thickness of the cavity wall at the second notch is 40μm to 63.5μm; the third weak portion includes a third notch, and the residual thickness of the cavity wall at the third notch is 64μm to 90.5μm.

[0013] In an example of the cylindrical battery cell of the present invention, along the height direction of the core rod, the core rod further includes a plurality of solid parts, at least part of which is arranged between adjacent sealed cavities.

[0014] In an example of the cylindrical battery cell of the present invention, the side wall of the core rod includes a convex portion protruding toward the hole wall side of the central hole, and the convex portion at least partially abuts against the hole wall of the central hole.

[0015] The cylindrical battery provided by the utility model has a sealed cavity for accommodating electrolyte on the core rod. When the cylindrical battery is assembled, part of the electrolyte can be stored in the sealed cavity in advance without contacting the electrode assembly, that is, it does not affect the infiltration effect of the electrolyte inside the electrode assembly, and ensures the normal cycle performance of the cylindrical battery; and because a weak part is provided on the cavity wall of the sealed cavity, the weak part can be broken when the internal pressure of the shell is greater than the set threshold, and the electrolyte in the sealed cavity can contact the electrode assembly, so that in the later stage of the cycle of the cylindrical battery, the electrolyte released after the weak part is broken can replenish the electrode assembly, improve the lack of liquid inside the electrode assembly, thereby delaying the attenuation of the cycle performance of the cylindrical battery, and correspondingly improving the service life of the cylindrical battery. At the same time, because the core rod is arranged in the central hole of the electrode assembly, it will not occupy the space of the cylindrical battery, so the volume energy density of the cylindrical battery can be guaranteed. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the utility model. For ordinary technicians in this field, other embodiments can be obtained based on these drawings without paying creative work.

[0017] Figure 1 It is a three-dimensional overall schematic diagram of an embodiment of a cylindrical battery cell of the utility model;

[0018] Figure 2 This is a cross-sectional view of the overall structure of an embodiment of a cylindrical battery cell of the utility model;

[0019] Figure 3 for Figure 2 A partial enlarged view of the middle area A;

[0020] Figure 4 for Figure 2 A partial enlarged view of the middle area B;

[0021] Figure 5 This is a schematic diagram of the location of the weak part on the sealed cavity in one embodiment of the cylindrical battery cell of the utility model;

[0022] Figure 6 This is a schematic diagram of the location of the notch on the sealed cavity in one embodiment of the cylindrical battery cell of the utility model;

[0023] Figure 7 for Figure 5 Cross-sectional view of the middle area in CC direction;

[0024] Figure 8 for Figure 7 A partial enlarged view of the middle area F;

[0025] Fig. 9 for Figure 5 Cross-sectional view of the middle area in the DD direction;

[0026] Fig.10 for Fig. 9 A partial enlarged view of the middle area E;

[0027] Fig.11 It is a structural schematic diagram of a cylindrical battery core in an embodiment of the utility model, in which a convex portion is arranged on the side wall of the core rod;

[0028] Fig.12 It is a structural schematic diagram of another embodiment of the cylindrical battery cell of the utility model, in which the side wall of the core rod is provided with a convex portion;

[0029] Fig.13It is a schematic diagram of the structure in which the protrusion of the core rod abuts against the hole wall of the center hole in one embodiment of the cylindrical battery core of the utility model.

[0030] Component number description

[0031] 100, cylindrical cell; 110, shell; 111, side wall; 112, end wall; 1121, terminal hole; 113, opening; 120, electrode assembly; 121, center hole; 122, first pole ear; 123, second pole ear; 130, core rod; 131, sealed cavity; 1311, first sealed cavity; 1312, second sealed cavity; 1313, third sealed cavity; 132, entity; 1321, first entity; 1322, second entity; 133, cavity wall; 134, convex portion; 135, injection Liquid hole; 136, sealing cap; 140, weak part; 141, first weak part; 142, second weak part; 143, third weak part; 144, notch; 1441, first notch; 1442, second notch; 1443, third notch; 150, electrode terminal; 151, conductive part; 152, first fixing part; 153, second fixing part; 160, end cap; 171, first current collecting component; 172, second current collecting component; 181, first insulating member; 182, second insulating member; 190, sealing member. DETAILED DESCRIPTION

[0032] The following describes the implementation of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific implementations, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the following embodiments and the features in the embodiments can be combined with each other without conflict. It should also be understood that the terms used in the embodiments of the present invention are intended to describe specific implementation schemes, rather than to limit the scope of protection of the present invention. The test methods for which specific conditions are not specified in the following examples are usually carried out under conventional conditions or under the conditions recommended by the manufacturers.

[0033] When numerical ranges are given in the embodiments, it should be understood that unless otherwise specified in the present invention, both endpoints of each numerical range and any value between the two endpoints can be selected. Unless otherwise defined, all technical and scientific terms used in the present invention are in accordance with the prior art mastery of those skilled in the art and the description of the present invention, and any prior art methods, equipment and materials similar or equivalent to the methods, equipment and materials in the embodiments of the present invention can also be used to implement the present invention.

[0034] It should be noted that the terms such as "upper", "lower", "left", "right", "middle" and "one" cited in this specification are only for the convenience of description and are not used to limit the scope of implementation of the present utility model. Changes or adjustments to their relative relationships should be regarded as the scope of implementation of the present utility model without substantially changing the technical content.

[0035] See also Figures 1 to 13 The utility model provides a cylindrical battery cell 100, which is provided with a core rod 130, and a sealed cavity 131 and a weak portion 140 are provided on the core rod 130. The weak portion 140 ruptures when the internal pressure of the shell 110 is greater than a set threshold value, so that the electrolyte in the sealed cavity 131 contacts the electrode assembly 120, thereby improving the technical problem that the cylindrical battery cell 100 is prone to lack of liquid during the recycling process, resulting in reduced cycle performance and service life of the cylindrical battery cell 100.

[0036] See also Figures 1 to 3 , the cylindrical battery cell 100 includes: a shell 110, an electrode assembly 120 and a core rod 130. An installation cavity is formed in the shell 110 for installing the electrode assembly 120, an electrolyte (not shown) and other components. The installation cavity can be open at one end or at both ends. Specifically, the size of the shell 110 can be determined according to the specific size of the electrode assembly 120, such as a diameter of 46 mm, a height of 80 mm, 95 mm, 120 mm and other specifications. The shell 110 can be in a variety of shapes, such as cylindrical, prismatic, etc. The material of the shell 110 can also be a variety of materials, such as copper, iron, aluminum, steel, aluminum alloy, etc. In order to prevent the shell 110 from rusting during long-term use, a layer of rust-proof material, such as metal nickel, etc., can also be plated on the surface of the shell 110.

[0037] See also Figure 1 and Figure 2 In an embodiment of the cylindrical battery cell 100 of the utility model, the housing 110 is a cylindrical structure, the housing 110 includes an end wall 112 and a side wall 111 surrounding the end wall 112, the housing 110 includes a closed end and an open end, the end wall 112 is the closed end, and the opening 113 opposite to the end wall 112 is the open end. The end wall 112 and the side wall 111 can be integrally formed and connected, or they can be formed separately and then welded.

[0038] See also Figure 2 and Figure 4, the end wall 112 includes a terminal hole 1121, and the electrode terminal 150 disposed on the side of the end wall 112 is installed through the terminal hole 1121. The shape of the terminal hole 1121 can be a circular hole, a square hole or other polygonal structures, as long as the fixed connection requirements of the electrode terminal 150 and the end wall 112 are met. The terminal hole 1121 can be set in the central area of ​​the end wall 112, or in the outer peripheral area of ​​the end wall 112, so as to correspond to the installation position of the electrode terminal 150. In this embodiment, the terminal hole 1121 is a circular hole structure, and the terminal hole 1121 is coaxially arranged with the end wall 112.

[0039] For details, please continue to see Figure 4 In an embodiment of the cylindrical battery cell 100 of the utility model, the electrode terminal 150 includes a conductive part 151, a first fixing part 152 and a second fixing part 153. The conductive part 151 is a cylindrical structure, and the conductive part 151 passes through the terminal hole 1121. The first fixing part 152 is arranged in the circumference of the outer end of the conductive part 151 and is clamped on the outer side of the end wall 112; the second fixing part 153 is arranged in the circumference of the inner end of the conductive part 151 and is clamped on the inner side of the end wall 112. The electrode terminal 150 is insulated and isolated from the end wall 112 by the first insulating member 181 and the second insulating member 182, respectively, and the terminal hole 1121 is sealed by the first fixing part 152 pressing the sealing member 190. The first insulating member 181 is disposed between the first fixing portion 152 and the outer wall of the end wall 112 to insulate the electrode terminal 150 from the outer wall of the end wall 112 ; the second insulating member 182 is installed between the second fixing portion 153 and the inner wall of the end wall 112 to insulate the electrode terminal 150 from the inner wall of the end wall 112 .

[0040] like Figure 2 and Figure 3As shown, the electrode assembly 120 is contained in the shell 110. The electrode assembly 120 is a component in the cylindrical battery cell 100 where an electrochemical reaction occurs. The shell 110 may contain one or more electrode assemblies 120. The electrode assembly 120 is mainly formed by winding or stacking the positive electrode sheet and the negative electrode sheet, and a separator is usually provided between the positive electrode sheet and the negative electrode sheet. Preferably, in the present embodiment, the electrode assembly 120 is wound by the positive electrode sheet, the negative electrode sheet and the separator, and a central hole 121 is formed in the central area of ​​the electrode assembly 120. The positive electrode sheet includes a positive current collector and a positive active material layer, and the positive active material layer is coated on the surface of the positive current collector; the positive current collector includes a positive coating area and a positive electrode ear connected to the positive coating area, the positive coating area is coated with a positive active material layer, and the positive electrode ear is not coated with a positive active material layer. The negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer, and the negative electrode active material layer is coated on the surface of the negative electrode current collector; the negative electrode current collector includes a negative electrode coating area and a negative electrode tab connected to the negative electrode coating area, the negative electrode coating area is coated with a negative electrode active material layer, and the negative electrode tab is not coated with a negative electrode active material layer. Taking a lithium-ion battery as an example, the material of the positive electrode current collector can be aluminum, and the positive electrode active material layer includes a positive electrode active material, and the positive electrode active material can be lithium cobalt oxide, lithium iron phosphate, ternary lithium or lithium manganese oxide. The material of the negative electrode current collector can be copper, and the negative electrode active material layer includes a negative electrode active material, and the negative electrode active material can be carbon or silicon. The main matrix material of the diaphragm can be PP or PE. In order to protect and insulate the electrode assembly 120, an insulating film can also be coated on the outside of the electrode assembly 120, and the insulating film can be synthesized from PP, PE, PET, PVC or other high molecular polymer materials.

[0041] Please continue reading Figure 2 In an example of the cylindrical battery cell 100 of the utility model, the electrode assembly 120 is sealed and installed in the housing 110. The electrode assembly 120 is provided with a first pole ear 122 and a second pole ear 123 at both ends of the cylindrical battery cell 100 in the height direction, and the polarities of the first pole ear 122 and the second pole ear 123 are opposite, wherein the first pole ear 122 faces the end wall 112 side, and the first pole ear 122 is a positive pole ear. It should be noted that in other embodiments, the first pole ear 122 may also be a negative pole ear, and the second pole ear 123 may be a positive pole ear.

[0042] See also Figures 2 to 4, on the side of the end wall 112 of the housing 110, the electrode terminal 150 may be directly electrically connected to the first pole tab 122, or may be indirectly electrically connected to the first pole tab 122 through a current collecting member; an end cap 160 is provided at the end of the opening 113 of the housing 110, and the end cap 160 is sealed and installed at the opening 113, and the end cap 160 may be electrically connected to the side wall 111, or may be electrically connected to the second pole tab 123 through a current collecting member. Preferably, in this embodiment, a first current collecting member 171 and a second current collecting member 172 are respectively provided at both ends of the electrode assembly 120, and the electrode terminal 150 is electrically connected to the first pole tab 122 through the first current collecting member 171, and the end cap 160 is electrically connected to the second pole tab 123 through the second current collecting member 172.

[0043] See also Figure 2 , Figure 3 and Figure 5 The cylindrical battery cell 100 further includes a core rod 130, which is at least partially disposed in the center hole 121, and the side wall of the core rod 130 is at least partially in contact with the hole wall of the center hole 121. The core rod 130 may be made of corrosion-resistant, high-temperature-resistant, and low-density materials such as aluminum, stainless steel, plastic, or graphite. Preferably, in this embodiment, the main body material of the core rod 130 is aluminum. The core rod 130 may be an approximately elongated cylindrical structure, or an elongated polyhedral structure or any other elongated rod-shaped structure that can be inserted into the center hole 121. Preferably, in this embodiment, the core rod 130 is an elongated cylindrical structure. Along the axial direction of the center hole 121, the core rod 130 may be fully inserted into the center hole 121, or may be partially inserted into the center hole 121, as long as it is ensured that at least part of the side wall of the core rod 130 can support the hole wall of the center hole 121. Preferably, in this embodiment, the height of the core rod 130 matches the depth of the center hole 121, and the core rod 130 is substantially completely inserted into the center hole 121. In this way, during the expansion process of the electrode assembly 120, the side wall of the core rod 130 can provide better support for the hole wall of the center hole 121, reduce the probability of the hole wall of the center hole 121 collapsing, and ensure the normal cycle performance of the cylindrical battery cell 100.

[0044] See also Figure 3 , Figure 5 and Figure 7The core rod 130 includes a sealed cavity 131 for containing electrolyte and a weak portion 140. The sealed cavity 131 includes a cavity wall 133. The weak portion 140 is arranged on the cavity wall 133. The weak portion 140 ruptures when the internal pressure of the shell 110 is greater than a set threshold value, so that the electrolyte in the sealed cavity 131 contacts the electrode assembly 120. The sealed cavity 131 can be any structure such as a cylindrical structure, a semi-cylindrical structure, a fan-shaped structure, etc., and the specific structure is based on the requirement of being able to accommodate the electrolyte of the set capacity. The number of sealed cavities 131 is not limited, and can be one or more; the location of the sealed cavity 131 on the core rod 130 is also not limited, for example, it can be set at the end of the core rod 130, or it can be set at any position such as the side wall of the core rod 130. The cavity wall 133 of the sealed cavity 131 may be a part of the side wall of the mandrel 130, or a part of the end wall 112 of the mandrel 130, or other wall structures facing the inside of the mandrel 130, etc., which is specifically determined by the setting position of the sealed cavity 131. Preferably, in this embodiment, the sealed cavity 131 is a cylindrical structure coaxially arranged with the mandrel 130, and such a setting facilitates the molding process of the sealed cavity 131 on the mandrel 130.

[0045] In order to facilitate the injection of electrolyte into the sealed cavity 131, in this embodiment, a liquid injection hole 135 for electrolyte to enter is further provided on the cavity wall 133 of the sealed cavity 131. Figure 3 As shown. A sealed cavity 131 may be provided with one or more injection holes 135, and the shape and size of the injection hole 135 match the liquid outlet of the injection device. A sealing cover 136 is also provided at the injection hole 135 to seal the injection hole 135 after the sealed cavity 131 is injected with liquid.

[0046] There are many ways to form the weak portion 140, for example, it can be a thinning area structure formed by machining notches on the cavity wall 133, or it can be an external explosion-proof valve plate structure installed on the cavity wall 133. As long as it is ensured that the weak portion 140 can be broken when the internal pressure of the shell 110 is greater than the set threshold, so that the electrolyte in the sealed cavity 131 contacts the electrode assembly 120, the specific setting position of the weak portion 140 on the cavity wall 133 is not limited. The weak portion 140 can be set on the side of the cavity wall 133 facing the hole wall of the central hole 121, so that when it is broken, the electrolyte in the sealed cavity 131 contacts the hole wall of the central hole 121, thereby infiltrating the electrode piece in the electrode assembly 120. The weak portion 140 can also be set at the position of the cavity wall 133 facing the end wall 112 of the core rod 130, so that when it is broken, the electrolyte in the sealed cavity 131 contacts the end faces of the electrode assembly 120, thereby infiltrating the electrode piece in the electrode assembly 120. Preferably, in this embodiment, please refer to Figure 5On the cavity wall 133 of the sealed cavity 131, the weak portion 140 is arranged facing the hole wall of the central hole 121. In this way, when the weak portion 140 is broken, the electrolyte in the sealed cavity 131 will contact the hole wall of the central hole 121, and then the central area of ​​the electrode assembly 120, which is most likely to be short of liquid, can be directly replenished in time, and the replenishment effect is better.

[0047] It should be noted that the specific size of the set threshold value in which the weak portion 140 can rupture when the internal pressure of the shell 110 is greater than the set threshold value is related to the internal pressure of the shell 110 during normal use of the cylindrical battery cell 100, and the set threshold value when the weak portion 140 ruptures is less than the opening pressure value of the explosion-proof valve of the cylindrical battery cell 100 itself, so that the weak portion 140 can be ensured to rupture during normal use of the cylindrical battery cell 100, so that after the electrolyte in the sealed cavity 131 replenishes the electrode assembly 120, the cylindrical battery cell 100 can still be recycled normally.

[0048] In this embodiment, by providing a sealed cavity 131 for accommodating electrolyte on the core rod 130, when the cylindrical battery cell 100 is assembled, part of the electrolyte can be stored in the sealed cavity 131 in advance, without contacting the electrode assembly 120, that is, it does not affect the infiltration effect of the electrolyte inside the electrode assembly 120, and ensures the normal cycle performance of the cylindrical battery cell 100; and in the later stage of the cycle of the cylindrical battery cell 100, when the internal pressure of the shell 110 is greater than the set threshold, the weak part 140 can be broken, and the electrolyte in the sealed cavity 131 is released, so that the electrolyte contacts the electrode assembly 120, so that the electrode assembly 120 can be replenished, and the lack of liquid inside the electrode assembly 120 can be improved, thereby delaying the attenuation of the cycle performance of the cylindrical battery cell 100 and correspondingly improving the service life of the cylindrical battery cell 100. At the same time, since the core rod 130 is arranged in the central hole 121 of the electrode assembly 120, it will not occupy the space of the cylindrical battery cell 100, and the volume energy density of the cylindrical battery cell 100 can be ensured.

[0049] The opening pressure of the weak portion 140 (i.e., the rupture pressure of the weak portion 140) directly affects the time for the electrolyte in the sealed cavity 131 to be released and discharged. If the opening pressure of the weak portion 140 is too small, the weak portion 140 will rupture too early, which will not only cause excessive electrolyte in the initial operation of the shell 110, affecting the normal cycle performance of the electrode assembly 120, but also fail to play a role in replenishing liquid when the electrode assembly 120 is short of liquid in the later stage. If the opening pressure of the weak portion 140 is too large, the weak portion 140 will rupture too late, making it impossible to release the electrolyte in time when the electrode assembly 120 is short of liquid, causing the electrode assembly 120 to run for a long time in a state of lack of liquid, reducing the cycle performance and service life of the cylindrical battery cell 100. Therefore, a reasonable opening pressure needs to be set for the weak portion 140. Preferably, in an example of the cylindrical battery cell 100 of the utility model, the opening pressure of the weak portion 140 is any value within the range of 0.35 to 1.55 MPa, for example, 0.35 MPa, 0.8 MPa, 1 MPa or 1.55 MPa. Setting the opening pressure of the weak portion 140 within the range of 0.35 to 1.55 MPa can meet the working pressure requirements of most conventional cylindrical battery cells 100, that is, when the cylindrical battery cell 100 lacks liquid in the later working period, the weak portion 140 will rupture accordingly, thereby allowing the electrode assembly 120 inside the housing 110 to be refilled at a better refilling time, thereby obtaining a better refilling effect. At the same time, setting the opening pressure of the weak portion 140 within the range of 0.35 to 1.55 MPa can also ensure that the opening pressure of the weak portion 140 is less than the opening pressure of the explosion-proof valve of the cylindrical battery cell 100 itself, thereby ensuring that the weak portion 140 can rupture during normal use of the cylindrical battery cell 100.

[0050] The volume of electrolyte stored in the sealed cavity 131 of the core rod 130 is related to the amount of liquid shortage in the later stage of the operation of the cylindrical battery cell 100, and is determined by the specifications of the cylindrical battery cell 100. When the volume of electrolyte stored in the core rod 130 is certain, the core rod 130 may be provided with one sealed cavity 131 or multiple sealed cavities 131, but preferably, in an example of the cylindrical battery cell 100 of the present invention, the core rod 130 includes multiple sealed cavities 131, and the multiple sealed cavities 131 are arranged in sequence along the height direction of the core rod 130. The multiple sealed cavities 131 may be cavities of the same size and volume, or cavities of different sizes and volumes. Preferably, in order to facilitate processing and manufacturing, in this embodiment, please refer to Figure 5 and Figure 7 The multiple sealed cavities 131 are cavities of the same size and volume. The multiple sealed cavities 131 are arranged in sequence along the height direction of the core rod 130. In this way, when the cavity walls 133 of the sealed cavities 131 at different heights are broken, the electrolyte can be released at different heights of the electrode assembly 120, thereby further improving the uniformity of the liquid replenishment effect in the central area of ​​the electrode assembly 120.

[0051] Along the height direction of the core rod 130, the plurality of sealed cavities 131 may be arranged end to end in sequence, or may be arranged in a spaced relationship between adjacent sealed cavities. Figures 5 to 7 Along the height direction of the core rod 130, the core rod 130 further includes a plurality of solid parts 132, which may be columnar structures of equal size and shape, or columnar structures of unequal size and shape. At least part of the solid parts 132 are arranged between adjacent sealed cavities 131, that is, adjacent sealed cavities 131 are indirectly connected through the solid parts 132. In this way, the plurality of sealed cavities 131 are dispersedly arranged in the height direction of the core rod 130, which can avoid the large attenuation of the overall strength of the core rod 130 caused by the centralized arrangement of the plurality of sealed cavities 131, thereby improving the support strength of the core rod 130 on the hole wall of the center hole 121, and reducing the probability of local collapse of the hole wall of the center hole 121.

[0052] Specifically, in this embodiment, please refer to Figure 5 and Figure 7 The mandrel 130 includes two first entity parts 1321 and a plurality of second entity parts 1322. The two first entity parts 1321 are respectively arranged at the two ends of the mandrel 130 in the height direction, and the plurality of second entity parts 1322 are respectively sandwiched between adjacent sealed cavities 131. This arrangement can make the two ends of the mandrel 130 in the height direction obtain better support strength, and reduce the probability of collapse of the hole wall of the center hole 121 at both ends in the height direction. In other embodiments, the mandrel 130 may also only include a plurality of second entity parts 1322, and the two ends of the mandrel 130 in the height direction are correspondingly provided with sealed cavities 131, and the plurality of second entity parts 1322 are respectively sandwiched between adjacent sealed cavities 131. This can also avoid the large attenuation of the overall strength of the mandrel 130 caused by the centralized arrangement of the plurality of sealed cavities 131, and improve the support strength of the mandrel 130 on the hole wall of the center hole 121.

[0053] It should be noted that there can be many ways to connect the sealed cavity 131 and the solid part 132. For example, the plate can be bent to form the cavity wall 133 of the sealed cavity 131, and then the two ends of the cavity wall 133 are welded to the solid part 132 respectively; or the sealed cavity 131 and the solid part 132 can be connected by an integral casting. This is not limited in the embodiments of the present invention.

[0054] Each sealed cavity 131 may be provided with one weak portion 140, or multiple weak portions 140 may be provided, so as to meet the discharge requirements of the electrolyte in the sealed cavity 131. Preferably, in an example of the cylindrical battery cell 100 of the present invention, refer to Figure 5, there are multiple weak parts 140, and the cavity wall 133 of each sealed cavity 131 is provided with several weak parts 140. For example, each sealed cavity 131 can be provided with one weak part 140, or two or more weak parts 140, etc., and the opening pressures of the weak parts 140 corresponding to at least two sealed cavities 131 in the multiple sealed cavities 131 are different. The opening pressures of the weak parts 140 are different, so that the rupture time of the weak parts 140 can be different, and then the electrolyte can be supplied in small amounts and multiple times during the operation of the cylindrical battery cell 100, which can further improve the uniformity of the liquid replenishment effect of the electrode assembly 120. In this embodiment, in order to facilitate the control of the opening pressure of the weak parts 140 on the sealed cavity 131, preferably, each sealed cavity 131 is correspondingly provided with a weak part 140, and the opening pressures of the weak parts 140 corresponding to each sealed cavity 131 are different.

[0055] Furthermore, in order to discharge the electrolyte in the sealed cavity 131 in maximum amount after the weak portion 140 is broken, in one example of the present invention, Figure 5 The X direction is the placement direction of the core rod 130 when the cylindrical battery cell 100 is in normal use, and the corresponding weak portion 140 on each sealed cavity 131 is arranged near the lower end of the sealed cavity 131. In this way, after the weak portion 140 is broken, the electrolyte in the sealed cavity 131 can be discharged from the lower broken position under the action of gravity, thereby reducing the retention amount of the electrolyte in the sealed cavity 131.

[0056] Considering the convenience of molding the weak portion 140 on the cavity wall 133 of the sealed cavity 131, preferably, in an example of the cylindrical battery cell 100 of the present invention, the weak portion 140 includes a notch 144. The notch 144 can have a variety of structural shapes. From the unfolded view of the cylindrical cavity wall 133 of the sealed cavity 131, the notch 144 can be a circular notch, an elliptical notch, etc. in a closed loop structure, or a cross notch or a double C-shaped notch in a non-closed loop structure. As long as the opening pressure of the notch 144 can be met, there is no specific limitation. By setting the notch 144, different opening pressures can be matched by processing different notch depths on the cavity wall 133, which is convenient for matching with different set opening pressures. At the same time, there is no need to add additional parts, so the overall manufacturing and processing cost and assembly efficiency of the core rod 130 can be saved.

[0057] Preferably, in an example of the cylindrical battery cell 100 of the utility model, from the unfolded view of the cylindrical cavity wall 133 of the sealed cavity 131, the notch 144 is an elliptical notch, and the long axis direction of the elliptical notch is consistent with the height direction of the core rod 130. In this way, when the rupture area on the cavity wall 133 is the same, the damage to the support strength of the cavity wall 133 can be weakened, so that the support strength of the core rod 130 on the hole wall of the center hole 121 can be guaranteed, and the probability of local collapse of the hole wall of the center hole 121 can be reduced, so that the service life of the cylindrical battery cell 100 can be better improved.

[0058] In an example of the cylindrical battery cell 100 of the present invention, the plurality of weak portions 140 are respectively a first weak portion 141, a second weak portion 142 and a third weak portion 143, and the plurality of sealed cavities 131 are respectively a first sealed cavity 1311, a second sealed cavity 1312 and a third sealed cavity 1313; the first weak portion 141, the second weak portion 142 and the third weak portion 143 are respectively correspondingly arranged at the cavity walls 133 of different sealed cavities 131, that is, the first weak portion 141 is arranged at the cavity wall 133 of the first sealed cavity 1311, the second weak portion 142 is arranged at the cavity wall 133 of the second sealed cavity 1312, and the third weak portion 143 is arranged at the cavity wall 133 of the third sealed cavity 1313. The first sealed cavity 1311, the second sealed cavity 1312 and the third sealed cavity 1313 may be arranged in sequence along the height direction of the core rod 130, or may be arranged in disorder, which is not limited thereto. For the convenience of description, in this embodiment, according to Figure 5 In the X-axis direction, the first sealed cavity 1311, the second sealed cavity 1312 and the third sealed cavity 1313 are arranged from top to bottom. The opening pressure of the first weak portion 141 is 0.35Mpa to 0.55Mpa, the opening pressure of the second weak portion 142 is 0.55Mpa to 0.75Mpa, and the opening pressure of the third weak portion 143 is 0.75Mpa to 1.25Mpa. With such arrangement, when the pressure of the cylindrical battery cell 100 changes from small to large in the later stage of the cycle, the first weak portion 141, the second weak portion 142 and the third weak portion 143 will rupture in sequence, thereby releasing the electrolyte in the first sealed cavity 1311, the second sealed cavity 1312 and the third sealed cavity 1313 to the electrode assembly 120 in different time periods, so as to complete multiple rehydration operations during the cycle of the electrode assembly 120, and further enable the electrode assembly 120 to obtain a better rehydration effect under the condition of the same total rehydration amount, thereby further improving the cycle performance and service life of the cylindrical battery cell 100.

[0059] In an example of the cylindrical battery cell 100 of the present invention, please refer to Figures 6 to 10The walls 133 of the first sealed cavity 1311, the second sealed cavity 1312 and the third sealed cavity 1313 are all made of aluminum. The specific thickness of the wall 133 is determined according to the compressive strength of the sealed cavity 131 during the use of the cylindrical battery cell 100. Preferably, in this embodiment, the thickness of the wall 133 is 400 μm. The first weak portion 141 includes a first notch 1441, and the residual thickness of the wall 133 of the first sealed cavity 1311 at the first notch 1441 is 20 μm to 39.5 μm; the second weak portion 142 includes a second notch 1442, and the residual thickness of the wall 133 of the second sealed cavity 1312 at the second notch 1442 is 40 μm to 63.5 μm; the third weak portion 143 includes a third notch 1443, and the residual thickness of the wall 133 of the third sealed cavity 1313 at the third notch 1443 is 64 μm to 90.5 μm. With this arrangement, the opening pressure of the first weak portion 141 arranged in the first sealed cavity 1311 can be 0.35Mpa~0.55Mpa, the opening pressure of the second weak portion 142 arranged in the second sealed cavity 1312 can be 0.55Mpa~0.75Mpa, and the opening pressure of the third weak portion 143 arranged in the third sealed cavity 1313 can be 0.75Mpa~1.55Mpa.

[0060] It should be noted that in other embodiments, when the cavity wall 133 is made of other materials, a residual thickness different from that in the above embodiments may be set at the cavity wall 133 at the notch 144 to achieve set opening pressures of different weak portions 140 .

[0061] In an example of the cylindrical battery cell 100 of the present invention, please refer to Figures 11 to 13 The side wall of the core rod 130 includes a convex portion 134 protruding toward the hole wall side of the center hole 121, and the convex portion 134 at least partially abuts against the hole wall of the center hole 121. The convex portion 134 can be arranged on the solid portion 132, or it can be arranged on the cavity wall 133 of the sealing cavity 131, as long as the convex portion 134 can at least partially abut against the hole wall of the center hole 121. The convex portion 134 can be connected to one side of the side wall of the core rod 130 by casting, or it can be connected to the side wall of the core rod 130 by bonding or welding. There are multiple convex portions 134, and the multiple convex portions 134 are dispersed on the side wall of the core rod 130. The structure of the convex portion 134 can be a hemispherical convex structure, such as Fig.11 As shown in FIG. 1 , when the electrode assembly 120 expands, the spherical surface of the protrusion 134 at least partially contacts the hole wall of the central hole 121. The structure of the protrusion 134 can also be a long strip structure, such as Fig.10As shown, when the electrode assembly 120 expands, the outer surface of the long strip abuts against the hole wall of the central hole 121. By providing the convex portion 134 on the side wall of the core rod 130, a gap can be formed between the cavity wall 133 of the sealed cavity 131 and the hole wall of the central hole 121 or between the solid portion 132 and the hole wall of the central hole 121, so that when the electrolyte in the sealed cavity 131 is released, the electrolyte can flow inside the central hole 121 through the gap to improve the diffusion efficiency of the electrolyte, which is more conducive to improving the liquid replenishment efficiency of the electrode assembly 120.

[0062] The cylindrical battery provided by the utility model has a sealed cavity for accommodating electrolyte on the core rod. When the cylindrical battery is assembled, part of the electrolyte can be stored in the sealed cavity in advance without contacting the electrode assembly, that is, it does not affect the infiltration effect of the electrolyte inside the electrode assembly, and ensures the normal cycle performance of the cylindrical battery; and in the later stage of the cycle of the cylindrical battery, when the internal pressure of the shell is greater than the set threshold, the weak part can be broken, and the electrolyte in the sealed cavity is released, so that the electrolyte contacts the electrode assembly, so that the electrode assembly can be replenished, and the lack of liquid inside the electrode assembly can be improved, thereby delaying the attenuation of the cycle performance of the cylindrical battery, and correspondingly improving the service life of the cylindrical battery. At the same time, the core rod arranged in the center hole can also support the center hole position of the electrode assembly, reduce the probability of collapse of the hole wall position of the center hole during the expansion process of the cylindrical battery, and further improve the cycle performance and service life of the cylindrical battery.

[0063] Therefore, the utility model effectively overcomes some practical problems in the prior art and thus has high utilization value and use significance. The above embodiments are only illustrative of the principle and efficacy of the utility model, and are not used to limit the utility model. Anyone familiar with this technology can modify or change the above embodiments without violating the spirit and scope of the utility model. Therefore, all equivalent modifications or changes made by those with ordinary knowledge in the relevant technical field without departing from the spirit and technical ideas disclosed by the utility model should still be covered by the claims of the utility model.

Claims

1. A cylindrical battery cell, characterized in that: include: case; An electrode assembly, sealed and mounted in the housing, the electrode assembly having a central hole; A core rod, at least partially disposed in the central hole, wherein a side wall of the core rod at least partially abuts against a hole wall of the central hole; Among them, the core rod includes a sealed cavity for accommodating electrolyte and a weak portion, the sealed cavity includes a cavity wall, the weak portion is arranged on the cavity wall, and the weak portion ruptures when the internal pressure of the shell is greater than a set threshold value, so that the electrolyte in the sealed cavity contacts the electrode assembly.

2. The cylindrical battery cell according to claim 1, characterized in that: The opening pressure of the weak portion is 0.35-1.55 MPa.

3. The cylindrical battery cell according to claim 1, characterized in that: The weak portion is arranged facing the hole wall of the central hole.

4. The cylindrical battery cell according to claim 3, characterized in that: The core rod comprises a plurality of sealed cavities, and the plurality of sealed cavities are arranged in sequence along the height direction of the core rod.

5. The cylindrical battery cell according to claim 4, characterized in that: There are a plurality of the weak parts, and the cavity wall of each of the sealed cavities is provided with a plurality of the weak parts, and the opening pressures of the weak parts corresponding to at least two of the sealed cavities are different.

6. The cylindrical battery cell according to claim 4, characterized in that: The weakened portion includes a score.

7. The cylindrical battery cell according to claim 4, characterized in that: The core rod includes a first weak portion, a second weak portion and a third weak portion, and the first weak portion, the second weak portion and the third weak portion are respectively arranged on different cavity walls of the sealed cavity; the opening pressure of the first weak portion is 0.35Mpa~0.55Mpa, the opening pressure of the second weak portion is 0.55Mpa~0.75Mpa, and the opening pressure of the third weak portion is 0.75Mpa-1.55Mpa.

8. The cylindrical battery cell according to claim 7, characterized in that: The cavity wall is made of aluminum, the first weak portion includes a first notch, and the residual thickness of the cavity wall at the first notch is 20μm to 39.5μm, the second weak portion includes a second notch, and the residual thickness of the cavity wall at the second notch is 40μm to 63.5μm, and the third weak portion includes a third notch, and the residual thickness of the cavity wall at the third notch is 64μm to 90.5μm.

9. The cylindrical battery cell according to any one of claims 1 to 8, characterized in that: Along the height direction of the core rod, the core rod further includes a plurality of solid parts, at least part of which is arranged between adjacent sealed cavities.

10. The cylindrical battery cell according to claim 9, characterized in that: The side wall of the core rod includes a convex portion protruding toward the hole wall side of the central hole, and the convex portion at least partially abuts against the hole wall of the central hole.

Images