Core rod for battery, battery and electric device

Abstract

The invention discloses a core rod for a battery, the battery and an electric device. The core rod comprises a core rod shell, the core rod shell comprises a bottom plate, a top cover and a barrel-shaped framework, the two ends of the barrel-shaped framework are connected with the bottom plate and the top cover respectively, the barrel-shaped framework comprises a hollowed-out structure and a hollow solid top connected with the hollowed-out structure, and the hollow solid top is connected with the top cover; and the permeable membrane is attached to the inner wall of the cylindrical framework, the thickness of the permeable membrane is 0.5-5.0 microns, the pore diameter of the permeable membrane is 3-20 nm, a containing space is defined by the permeable membrane and the core rod shell, and the containing space is used for storing electrolyte. The permeable membrane in the core rod has proper thickness and pore diameter, the additive in the electrolyte stored in the core rod can be slowly released, and the additive enters the electrolyte outside the core rod from the hollow area of the cylindrical framework, so that the concentration of the additive in the electrolyte outside the core rod is kept in a proper range, and the electrolyte is prevented from being damaged. Therefore, the service life of the battery cell is prolonged, and the impedance of the battery cell cannot be quickly increased.

Description

Technical Field

[0001] The present application relates to the field of batteries, and in particular to a core rod for a battery, a battery, and an electrical device. Background Art

[0002] Currently, smaller cylindrical battery sizes, such as 18650 (18mm diameter, 65mm height) and 21700 (21mm diameter, 70mm height), are widely used in consumer electronics. In the power battery sector, major manufacturers are actively developing larger cylindrical cells with higher energy content, such as 4680 (46mm diameter, 80mm height) and 4690 (46mm diameter, 90mm height), to meet growing market demand. However, the development difficulty of cylindrical cells increases with the size of the cells. For example, as the diameter of the winding core increases, its radial heat dissipation capacity decreases. Heat generated during charging and discharging accumulates near the center of the winding, causing temperatures to be higher than those at the outer diameter. Similarly, as the height of the winding core increases, the difference in axial heat dissipation causes temperatures in the middle to be higher than at the ends. As a result, the temperature difference between the center and the outer shell of large cylindrical cells during charging and discharging can often reach as high as 5°C-10°C. This accelerates the consumption of life-saving electrolyte additives (such as vinylene carbonate (VC)) by the active materials near the winding center, shortening the battery cell's lifespan. If a high concentration of electrolyte additives is added to the battery cell at the beginning, it will cause the electrolyte additives to form a thick film on the negative electrode, affecting the low-temperature and fast-charging performance of the battery cell. Therefore, it is best to maintain the concentration of electrolyte additives in the battery cell at an appropriate concentration.

[0003] However, the current core rod is difficult to play the role of maintaining the concentration of additives in the electrolyte within an appropriate range. Summary of the Invention

[0004] The present application aims to alleviate or solve at least one of the above-mentioned problems to at least some extent.

[0005] In some embodiments of the present application, a core rod for a battery is provided. In some embodiments of the present application, the core rod comprises:

[0006] A mandrel housing, the mandrel housing comprising a bottom plate, a top cover, and a cylindrical frame, the ends of the cylindrical frame being respectively connected to the bottom plate and the top cover, the cylindrical frame comprising a hollow structure and a hollow solid top connected to the hollow structure, the hollow solid top being connected to the top cover;

[0007] A permeable membrane is attached to the inner wall of the cylindrical skeleton, the thickness of the permeable membrane is 0.5 μm-5.0 μm, the pore size of the permeable membrane is 3 nm-20 nm, and the permeable membrane and the core rod shell define a storage space for storing electrolyte.

[0008] The permeable membrane in the core rod has a suitable thickness and pore size, which can slowly release the additives in the electrolyte stored in the core rod driven by the concentration difference between the inside and outside of the core rod. The additives enter the electrolyte outside the core rod from the hollow area of the tubular skeleton, thereby maintaining the concentration of the additives in the electrolyte outside the core rod within a suitable range, which is beneficial to extending the service life of the battery cell, and the impedance of the battery cell will not increase rapidly.

[0009] In some embodiments of the present application, the cylindrical skeleton further includes a hollow solid bottom, which is connected to the bottom plate.

[0010] In some embodiments of the present application, the material of the permeable membrane includes at least one of polyimide, polyetherimide, polybenzimidazole, polyacrylonitrile, polyethersulfone, and polyamide. These materials have good resistance to electrolyte corrosion, and when used in the mandrel, the mandrel can maintain good stability.

[0011] In some embodiments of the present application, the permeable membrane is a cylindrical structure with one end open or a cylindrical structure with both ends open.

[0012] In some embodiments of the present application, the material of the bottom plate, the material of the top cover, and the material of the cylindrical frame each independently include at least one of polytetrafluoroethylene, polyetheretherketone, and polyphenylene sulfide. These materials have high strength, and the core rod shell is a hard shell that can maintain its shape substantially unchanged during the battery cell winding process. These materials also have good corrosion resistance and maintain good stability in the electrolyte.

[0013] In some embodiments of the present application, the material of the bottom plate, the material of the top cover and the material of the cylindrical frame are the same.

[0014] In some embodiments of the present application, the bottom plate and the cylindrical frame are an integral structure; and / or the top cover and the cylindrical frame are connected by bonding or threading.

[0015] In some embodiments of the present application, the shape of the hollow area of the hollow structure includes at least one of polygonal, circular, elliptical, and irregular shapes; and / or the core rod is a cylindrical core rod.

[0016] In another aspect of the present application, the present application provides a battery. In some embodiments of the present application, the battery includes:

[0017] shell;

[0018] The mandrel described above, wherein the mandrel is located in the housing;

[0019] A wound battery cell, comprising a positive electrode sheet, a separator and a negative electrode sheet, the wound battery cell being located in the housing and wrapped around the outside of the cylindrical skeleton of the core rod;

[0020] A first electrolyte is stored in the core rod, and a second electrolyte is stored outside the core rod. The first electrolyte and the second electrolyte contain the same additive, and the concentration of the additive in the first electrolyte is greater than the concentration of the additive in the second electrolyte.

[0021] As a result, this battery possesses all the features and advantages of the mandrel described above, which will not be elaborated here. During the battery cycle, the additives in the first electrolyte are released into the second electrolyte through the osmotic membrane driven by the concentration difference between the internal and external additives, maintaining a dynamic equilibrium in the additive concentration of the second electrolyte, thereby extending the battery's service life.

[0022] In some embodiments of the present application, the additive includes at least one of vinylene carbonate, fluoroethylene carbonate, 1,3-propane sultone, lithium difluorophosphate, and lithium bis(oxalatoborate).

[0023] In some embodiments of the present application, the battery is a cylindrical battery.

[0024] In another aspect of the present application, an electrical device is provided. In some embodiments of the present application, the electrical device includes the aforementioned battery. Thus, the electrical device has all the features and advantages of the aforementioned battery, which will not be further elaborated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0026] Figure 1 A schematic structural diagram of a mandrel housing according to an embodiment of the present application is shown;

[0027] Figure 2 A schematic diagram of the structure of a core rod shell expanded radially according to one embodiment of the present application is shown;

[0028] Figure 3 A schematic structural diagram of a permeable membrane according to an embodiment of the present application is shown;

[0029] Figure 4 shows a top view of a permeable membrane according to one embodiment of the present application;

[0030] Figure 5 shows a top view of a permeable membrane according to another embodiment of the present application;

[0031] Figure 6 A schematic diagram of the structure of a permeable membrane deployed radially according to one embodiment of the present application is shown;

[0032] Figure 7 A schematic structural diagram of a core rod deployed radially according to an embodiment of the present application is shown;

[0033] Figure 8 Shows Figure 7 The cross-sectional view of the core rod along the AA' direction;

[0034] Figure 9 A schematic diagram of a partial structure of a core rod expanded radially according to an embodiment of the present application is shown;

[0035] Figure 10 Shows Figure 9 The cross-sectional view of the core rod along the BB' direction;

[0036] Figure 11 A schematic structural diagram of a mandrel housing according to another embodiment of the present application is shown;

[0037] Figure 12 A schematic structural diagram of a core rod shell according to another embodiment of the present application is shown;

[0038] Figure 13 A schematic structural diagram showing a core rod radially expanded according to another embodiment of the present application is shown;

[0039] Figure 14 A schematic structural diagram of a mandrel housing according to another embodiment of the present application is shown;

[0040] Figure 15 Shows Figure 14 Schematic diagram of the structure of the core rod shell expanded radially;

[0041] Figure 16 A schematic structural diagram of a core rod deployed radially according to another embodiment of the present application is shown;

[0042] Figure 17 A schematic structural diagram of a mandrel housing according to another embodiment of the present application is shown;

[0043] Figure 18 Shows Figure 17 A schematic diagram of the structure of the core rod shell in the radial direction;

[0044] Figure 19 A schematic structural diagram of a core rod expanded radially according to yet another embodiment of the present application is shown.

[0045] Description of reference numerals:

[0046] 10: core rod shell; 100: bottom plate; 200: cylindrical frame; 201: outer wall; 202: inner wall; 210: hollow structure; 220: hollow solid top; 230: hollow solid bottom; 300: top cover; 20: permeable membrane. DETAILED DESCRIPTION

[0047] The following describes in detail embodiments of the present application. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application and are not to be construed as limiting the present application.

[0048] The current winding process for large cylindrical cells uses a long, thin core rod as an axis, around which the electrode is quickly wound to form a core. Depending on the process, the core rod can be retained in the core or pulled out, leaving a hollow cylindrical space. The center hole then serves as a flow channel and storage space for the electrolyte in the subsequent injection process and is retained until the cell is completed. The current center hole design fails to effectively solve the problem of accelerated consumption of electrolyte additives caused by high temperatures in the center of large cylindrical cells, nor does it maintain the additive concentration within an appropriate range.

[0049] In order to at least alleviate or solve at least one of the above technical problems to a certain extent, in one aspect of the present application, the present application proposes a core rod for a battery. In some embodiments of the present application, reference is made to Figures 1 to 3 、 Figures 6 to 8 The core rod includes a core rod shell 10 and a permeable membrane 20.

[0050] In some embodiments of the present application, reference is made to Figure 1 and Figure 2 The core rod shell 10 includes a bottom plate 100, a top cover 300 and a cylindrical frame 200. The two ends of the cylindrical frame 200 are respectively connected to the bottom plate 100 and the top cover 300. The cylindrical frame 200 includes a hollow structure 210 and a hollow solid top 220 connected to the hollow structure 210. The hollow solid top 220 is connected to the top cover 300. Figure 3 、 Figures 6 to 10 The permeable membrane 20 is attached to the inner wall 202 of the cylindrical frame 200. The thickness of the permeable membrane 20 can be 0.5 μm-5.0 μm, the pore size of the permeable membrane 20 can be 3 nm-20 nm, and the permeable membrane 20 and the core rod shell 10 define a storage space for storing electrolyte. In some embodiments, reference Figure 8 and Figure 10The thickness h of the permeable membrane 20 can be 0.5 μm, 0.8 μm, 1.0 μm, 1.5 μm, 2.0 μm, 2.5 μm, 3.0 μm, 4.0 μm or 5.0 μm. In some embodiments, the pore size of the permeable membrane 20 can be 3 nm, 5 nm, 8 nm, 10 nm, 13 nm, 15 nm, 17 nm or 20 nm.

[0051] The containment space formed by the permeable membrane and the core rod shell is used to contain the electrolyte. The electrolyte in the core rod is sealed in this containment space. The additives in the electrolyte can only be released outward under the action of the concentration difference between the inside and the outside, and are released to the outside of the core rod shell through the hollow area of the hollow structure. The thickness and pore size of the permeable membrane are both within a suitable range. The additives in the electrolyte can be slowly released outward under the drive of the concentration difference between the inside and the outside, so that the concentration of the additives in the electrolyte outside the core rod shell can be maintained within a suitable range, thereby helping to delay the battery cycle attenuation and extend the battery life. If the permeable membrane is too thick or the pore size is too small, the electrolyte additives in the core rod are difficult to release outward, and the electrolyte additives outside the core rod cannot be replenished in time when consumed. The capacity retention rate of the battery decreases rapidly during the cycle, which is not conducive to extending the battery life. If the permeable membrane is too thin or the pore size is too large, the electrolyte additives in the core rod are quickly released from the permeable membrane and enter the electrolyte outside the core rod, which will cause the battery impedance to increase rapidly, which is not conducive to improving the overall performance of the battery.

[0052] In some embodiments of the present application, the core rod may be a cylindrical core rod, that is, the cross section of the core rod perpendicular to its height is circular. The cylindrical core rod can be used to wind a cylindrical battery cell to prepare a cylindrical battery.

[0053] In some embodiments of the present application, reference is made to Figure 3 and Figure 4 , Figure 4 Can be seen as Figure 3 The permeable membrane can be a cylindrical structure with openings at both ends.

[0054] In other embodiments of the present application, reference is made to Figure 3 and Figure 5 , Figure 5 Can be seen as Figure 3 The top view shows that the permeable membrane can be a cylindrical structure with one end open. The permeable membrane is open at one end close to the top cover. After the electrolyte is injected into the core rod, the top cover is closed to seal the electrolyte in the accommodation space defined by the permeable membrane and the core rod shell.

[0055] In some embodiments of the present application, reference is made to Figure 6The permeable membrane 20 is radially expanded into a rectangle, where one side of the rectangle is the same length as the height of the permeable membrane, and the other side adjacent thereto is the circumference of the cross section (circle) of the permeable membrane perpendicular to the height direction.

[0056] In some embodiments of the present application, the material of the permeable membrane may include at least one of polyimide (PI), polyetherimide (PEI), polybenzimidazole (PBI), polyacrylonitrile (PAN), polyethersulfone (PES), and polyamide (PA). In some embodiments, the material of the permeable membrane may include polyimide, polyetherimide, polybenzimidazole, polyacrylonitrile, polyethersulfone, or polyamide. In other embodiments, the material of the permeable membrane may include two or more of polyimide, polyetherimide, polybenzimidazole, polyacrylonitrile, polyethersulfone, and polyamide. The above materials have good resistance to electrolyte corrosion and can maintain good stability during cyclic charge and discharge.

[0057] In some embodiments, the permeable membrane may be directly attached to the inner wall of the cylindrical frame.

[0058] In other embodiments, the permeable membrane may be attached to the inner wall of the cylindrical frame by gluing, thereby further improving the overall stability of the core rod. The specific material of the glue used is not particularly limited in this application, and those skilled in the art may select it according to actual needs, as long as the glue can achieve a strong bond between different structures and has electrolyte corrosion resistance. The glue material mentioned below is also not specifically limited.

[0059] In some embodiments of the present application, reference is made to Figure 1 、 Figure 2 and Figure 7 The hollow structure 210 of the cylindrical frame 200 is connected to the base plate 100. In some embodiments, the permeable membrane has an open structure at both ends, and the end of the permeable membrane near the base plate can be sealed by gluing. That is, the end of the permeable membrane near the base plate can be sealed with glue to prevent the electrolyte in the core rod from flowing out from the base plate of the core rod. In other embodiments, the permeable membrane has an opening at one end, and the side of the permeable membrane near the base plate can be sealed without additional operation.

[0060] In some embodiments of the present application, the top cover 300 can be connected to the cylindrical frame 200 by bonding or threading. Using the above method to connect the top cover to the cylindrical frame can achieve a sealing effect, so that the additives in the electrolyte can only be released outward due to the concentration difference between the inside and the outside.

[0061] In some embodiments, reference Figures 7 to 10Part of the permeable membrane 20 is attached to the hollow structure 210, and the other part is attached to the hollow solid top 220. It should be noted that the difference between the hollow structure 210 and the hollow solid top 220 is that the hollow structure 210 has multiple hollow areas, while the hollow solid top 220 is hollow in the middle, but there is no hollow area on the wall of the hollow solid top 220.

[0062] In some embodiments, reference Figure 7 and Figure 8 , Figure 8 for Figure 7 The cross-sectional view of the core rod along the AA' direction in FIG. 2 shows that the hollow structure 210 can be fence-shaped, including a strip-shaped solid portion and a strip-shaped hollow area between the solid portions. The hollow structure 210 has an outer wall 201 and an inner wall 202, and the outer wall 201 is away from the hollow area of the cylindrical frame 200.

[0063] In some embodiments, reference Figure 9 and Figure 10 , Figure 10 for Figure 9 In the cross-sectional view of the core rod along the BB' direction, the permeable membrane can cover a portion of the inner wall of the hollow solid top 220. In this case, the hollow solid top 220 can be connected to the top cover 300 by gluing or threading to achieve a seal. When the hollow solid top 220 is connected to the top cover 300 by threading, the area of the inner wall of the hollow solid top 220 that is not in contact with the permeable membrane 20 can be provided with threads.

[0064] In other embodiments, the permeable membrane 20 may completely cover the inner wall of the hollow solid top 220. In this case, the hollow solid top 220 may be connected to the top cover 300 by gluing to achieve sealing.

[0065] In some embodiments of the present application, reference is made to Figure 1 、 Figure 2 and Figure 7 The cylindrical skeleton 200 may be composed of a hollow structure 210 and a hollow solid top 220. In this case, the hollow structure 210 may be connected to the bottom plate 100 by gluing, or the hollow structure 210 and the bottom plate 100 may be an integral structure, which has better stability and is more conducive to improving the overall performance of the mandrel.

[0066] In some embodiments of the present application, reference is made to Figures 11 to 13In addition to the hollow structure 210 and the hollow solid top 220, the cylindrical frame 200 may further include a hollow solid bottom 230, which is connected to the bottom plate 100. In this case, the hollow solid bottom 230 may be connected to the bottom plate 100 by gluing, or the hollow solid bottom 230 may be connected to the bottom plate 100 by screwing, or the hollow solid bottom 230 and the bottom plate 100 may be an integral structure.

[0067] In some embodiments, the bottom plate 100 , the hollow solid bottom 230 , and the hollow structure 210 may be an integrated structure.

[0068] In some embodiments, reference Figure 13 In some embodiments, the permeable membrane 20 may cover a portion of the inner wall of the hollow solid bottom 230. In other embodiments, the permeable membrane 20 may completely cover the inner wall of the hollow solid bottom 230.

[0069] In some embodiments, when the cylindrical skeleton 200 includes a hollow structure 210, a hollow solid top 220 and a hollow solid bottom 230, the permeable membrane 20 can be a cylindrical structure with openings at both ends, and the end of the permeable membrane 20 close to the base plate 100 can be sealed by gluing, and the permeable membrane can cover a portion of the inner wall of the hollow solid bottom 230 or completely cover the inner wall of the hollow solid bottom 230.

[0070] In other embodiments, when the cylindrical skeleton 200 includes a hollow structure 210, a hollow solid top 220 and a hollow solid bottom 230, the permeable membrane 20 can be a cylindrical structure with one end open, and the end of the permeable membrane close to the bottom plate 100 does not require additional sealing treatment.

[0071] In some embodiments of the present application, the material of the bottom plate 100, the material of the top cover 300, and the material of the tubular frame 200 may each independently include at least one of polytetrafluoroethylene (PTFE), polyetheretherketone (PEEK), and polyphenylene sulfide (PPS). In some embodiments, the material of the bottom plate 100, the material of the top cover 300, and the material of the tubular frame 200 may each independently include polytetrafluoroethylene, polyetheretherketone, or polyphenylene sulfide. In other embodiments, the material of the bottom plate 100, the material of the top cover 300, and the material of the tubular frame 200 may each independently include two or more of polytetrafluoroethylene, polyetheretherketone, and polyphenylene sulfide.

[0072] In some embodiments of the present application, the material of the bottom plate, the material of the top cover and the material of the cylindrical frame can be the same. Thus, the same material can be used to prepare various parts of the mandrel shell, which is more conducive to setting process parameters.

[0073] In some embodiments of the present application, the bottom plate 300 and the cylindrical frame 200 can be an integral structure. Using the same material to prepare the bottom plate and the cylindrical frame, the bottom plate and the cylindrical frame can be integrally formed, which is beneficial to saving process steps and is beneficial to improving the overall strength and stability of the bottom plate and the cylindrical frame.

[0074] In some embodiments of the present application, the hollow regions of the hollow structure 210 may be in the shape of at least one of a polygon (including a triangle, rectangle, rhombus, pentagon, hexagon, etc.), a circle, an ellipse, and a special shape. The present application does not impose any specific restrictions on the number of hollow regions or the size of each hollow region, as long as the core rod can maintain good structural stability and maintain its shape during the winding process of the battery cell.

[0075] In addition to the aforementioned case where the hollow structure 210 may be in a fence shape, the hollow structure 210 may also be in other shapes.

[0076] In some embodiments of the present application, reference is made to Figures 14 to 16 , the hollow structure 210 may be honeycomb-shaped. Figures 14 to 16 The cylindrical frame 200 may be composed of a hollow solid top 220 and a honeycomb hollow structure 210, wherein the hollow solid top 220 is connected to the top cover 300, and the honeycomb hollow structure 210 is connected to the bottom plate 100. In some embodiments, Figure 16 The permeable membrane 20 may cover a portion of the inner wall of the hollow solid top 220. In other embodiments, the permeable membrane 20 may also completely cover the inner wall of the hollow solid top 220.

[0077] In other embodiments of the present application, reference is made to Figures 17 to 19 , the hollow structure 210 may be in a mesh shape. Figures 17 to 19 The cylindrical frame 200 may be composed of a hollow solid top 220 and a mesh hollow structure 210, wherein the hollow solid top 220 is connected to the top cover 300, and the mesh hollow structure 210 is connected to the bottom plate 100. In some embodiments, Figure 19 In some embodiments, the permeable membrane 20 may cover a portion of the inner wall of the hollow solid top 220. In other embodiments, the permeable membrane 20 may completely cover the inner wall of the hollow solid top 220.

[0078] In some embodiments, the cylindrical skeleton 200 may be composed of a hollow solid top 220 , a honeycomb-shaped hollow structure 210 and a hollow solid bottom, and the hollow solid bottom is connected to the bottom plate 300 .

[0079] In other embodiments, the cylindrical skeleton 200 may be composed of a hollow solid top 220 , a mesh-like hollow structure 210 and a hollow solid bottom, and the hollow solid bottom is connected to the bottom plate 300 .

[0080] In some embodiments, the core rod fabrication process proposed in this application is as follows: a permeable membrane is attached to the inner wall of a cylindrical frame, an electrolyte containing a high concentration of an additive is injected into the core rod from the top of the core rod, and the top of the core rod is sealed, so that the encapsulated additive can only be slowly released outward by the permeable membrane driven by the concentration difference between the inside and outside. The sealing method can be to bond the top cover to the top of the hollow body, or to create a threaded seal between the top of the hollow body and the top cover.

[0081] During the winding production process of the battery cell, the core rod serves as the winding center, and the positive electrode sheet, separator, and negative electrode sheet are wound around the core rod to form a core. The core rod is retained within the core rod and then removed from the production line according to the normal cylindrical battery cell production process. During the battery cell's service life, as the battery cell's charge and discharge cycles progress, the additives in the electrolyte outside the core rod are gradually decomposed and consumed, and the concentration of the additives outside the core rod decreases. Driven by the concentration difference between the inside and outside of the core rod, the additives stored in the core rod are released through the osmotic membrane into the external electrolyte, maintaining a dynamic balance in the additive concentration of the external electrolyte, thereby extending the service life of the cylindrical battery cell.

[0082] Unlike the traditional cylindrical battery cell design in which the core rod is pulled out to leave a center hole structure or the core rod with no additional function is retained therein, the present application designs a core rod with an additive slow-release function. The advantage of this design is that it can make full use of the original center hole structure of the cylindrical battery cell core, store the electrolyte additives that need to be slowly released therein using a permeable membrane, and gradually release the electrolyte additives during the service life of the cylindrical battery cell, so that the concentration of the additives in the electrolyte outside the core rod is maintained within an appropriate concentration range, thereby extending the service life of the battery cell; there is no need to change the original winding production process, and only the traditional core rod with no additional function needs to be replaced with the core rod proposed in this application.

[0083] In another aspect of the present application, the present application proposes a battery. In some embodiments of the present application, the battery may include a shell, the core rod described above, and a wound battery cell. The core rod is located in the shell; the wound battery cell includes a positive electrode sheet, a diaphragm, and a negative electrode sheet. The wound battery cell is located in the shell, and the wound battery cell is wrapped around the outside of the cylindrical skeleton of the core rod; a first electrolyte is stored in the core rod, and a second electrolyte is stored outside the core rod (the second electrolyte is located in the shell). The additives in the first electrolyte and the second electrolyte are the same, and the concentration of the additives in the first electrolyte is greater than the concentration of the additives in the second electrolyte. Thus, during the use of the battery, the additives in the first electrolyte will be slowly released outwards driven by the concentration difference between the inside and the outside, enter the electrolyte outside the core rod, replenish the additives for the second electrolyte, and maintain the concentration of the additives in the second electrolyte within an appropriate range, thereby extending the service life of the battery.

[0084] In some embodiments of the present application, the additive may include at least one of vinylene carbonate (VC), fluoroethylene carbonate (FEC), 1,3-propane sultone (PS), lithium difluorophosphate (LiPO2F2), and lithium bis(oxalatoborate) (LiBOB). In some embodiments of the present application, the additive may include vinylene carbonate, fluoroethylene carbonate, 1,3-propane sultone, lithium difluorophosphate, or lithium bis(oxalatoborate). In other embodiments, the additive may include two or more of vinylene carbonate, fluoroethylene carbonate, 1,3-propane sultone, lithium difluorophosphate, and lithium bis(oxalatoborate).

[0085] It should be noted that the concentration of the additive in the first electrolyte is greater than the concentration of the additive in the second electrolyte, which refers to the concentration of the same additive.

[0086] In some specific embodiments, the additive may be vinylene carbonate (VC).

[0087] In some embodiments of the present application, the battery may be a cylindrical battery.

[0088] The material, thickness and other characteristics of the positive electrode sheet, separator and negative electrode sheet are not specifically limited in this application, and those skilled in the art can select and set them according to actual conditions.

[0089] In some embodiments, the battery may be a lithium-ion battery.

[0090] In another aspect of the present application, an electrical device is provided. In some embodiments of the present application, the electrical device includes the aforementioned battery. Thus, the electrical device has all the features and advantages of the aforementioned battery, which will not be further elaborated here.

[0091] The present application will be described below by specific examples, and it will be appreciated by those skilled in the art that the following specific examples are merely for illustrative purposes and are not intended to limit the scope of the present application in any way. In addition, in the following examples, unless otherwise specified, the materials and equipment employed are all commercially available. If, in the following examples, specific processing conditions and treatment methods are not clearly described, then conditions and methods well known in the art may be used to process.

[0092] According to the standard process of lithium-ion batteries, a cylindrical battery of lithium iron phosphate-graphite system was prepared. The electrolyte was 1.2MLiPF6+EC / DEC (the mass ratio of EC to DEC was 50:50), and the additive was VC. The core rods and additives of each embodiment and comparative example were designed as shown in Table 1. Figure 1 In the structure shown, the permeable membrane adopts a cylindrical structure with one end open.

[0093] Table 1

[0094]

[0095] During production, the total amount of electrolyte injected was kept consistent between the embodiment and the comparative example.

[0096] The cylindrical batteries of each embodiment and comparative example were subjected to performance tests, including DCIR (direct current impedance) test and cycle performance test. The test results are recorded in Table 2.

[0097] DCIR test:

[0098] Test conditions: 25°C, adjust the cylindrical battery to 60% SOC, discharge at 3C for 10s, and calculate the DC impedance (DCIR).

[0099] 45℃ cycle test:

[0100] Test conditions: 45°C, 2.0V-3.75V, 500 cycles of 0.5C charge / 1C discharge, and calculation of capacity retention.

[0101] Table 2

[0102] DCIR growth after 500 cycles / % 500 cycles capacity retention rate / % Example 1 5.4 93.7 Example 2 6.8 93.5 Example 3 5.2 93.2 Example 4 5.3 92.5 Example 5 6.1 92.8 Comparative Example 1 4.8 90.8 Comparative Example 2 8.6 93.2 Comparative Example 3 8.0 93.3 Comparative Example 4 5.1 91.1 Comparative Example 5 4.9 90.9 Comparative Example 6 7.9 93.3

[0103] As a commonly used life additive, VC continuously forms a film on the negative electrode during high-temperature cycles to repair the damaged SEI (solid electrolyte interface film), thereby delaying the attenuation of battery capacity. As can be seen from Table 2, compared with Comparative Example 1, in which only 2wt% VC was added, the VC pre-stored in the central hole core rod of Examples 1 to 5 can continuously replenish the external electrolyte during cycling at 45°C. Ultimately, the batteries of Examples 1 to 5 have a higher capacity retention rate after 500 cycles. While the initial VC addition amount of Comparative Example 2 is relatively high, its one-time film formation on the negative electrode will bring about a large impedance increase, as can be seen from Table 2; the sustained release of VC in Examples 1 to 5 can maintain the VC concentration of the external electrolyte at a reasonable level, and the impedance growth is slow.

[0104] Compared with Examples 1-5, the thickness or pore size of the permeable membranes in Comparative Examples 3-6 falls outside the specified range. When the permeable membrane is too thick (Comparative Example 4) or too small (Comparative Example 5), the VC within the core rod is difficult to release during the cycle, and the external VC cannot be replenished in time when it is consumed. The battery's capacity retention rate decreases rapidly, and the capacity retention rate after 500 cycles is low. When the permeable membrane is too thin (Comparative Example 3) or too large (Comparative Example 6), VC is released from the permeable membrane too quickly, causing a rapid increase in impedance and adversely affecting the overall performance of the battery.

[0105] In the description of this application, the terms "inside", "outside", "top", "bottom", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing this application and do not require that this application must be constructed and operated in a specific orientation. Therefore, they should not be understood as limitations on this application.

[0106] In the description of this specification, the description with reference to the terms "some embodiments", "other embodiments", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment are included in at least one embodiment of the present application. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples, unless they are contradictory. In addition, it should be noted that in this specification, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated.

[0107] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations on the present application. Ordinary technicians in this field can change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. A core rod for a battery, characterized in that: The mandrel comprises: A mandrel housing, the mandrel housing comprising a bottom plate, a top cover, and a cylindrical frame, the ends of the cylindrical frame being respectively connected to the bottom plate and the top cover, the cylindrical frame comprising a hollow structure and a hollow solid top connected to the hollow structure, the hollow solid top being connected to the top cover; A permeable membrane is attached to the inner wall of the cylindrical skeleton, the thickness of the permeable membrane is 0.5 μm-5.0 μm, the pore size of the permeable membrane is 3 nm-20 nm, and the permeable membrane and the core rod shell define a storage space for storing electrolyte.

2. The mandrel according to claim 1, characterized in that The cylindrical frame further includes a hollow solid bottom, which is connected to the bottom plate.

3. The mandrel according to claim 1 or 2, characterized in that The material of the permeable membrane includes at least one of polyimide, polyetherimide, polybenzimidazole, polyacrylonitrile, polyethersulfone, and polyamide; And / or, the permeable membrane is a cylindrical structure with one end open or a cylindrical structure with both ends open.

4. The mandrel according to any one of claims 1 to 3, characterized in that The material of the bottom plate, the material of the top cover, and the material of the cylindrical frame each independently include at least one of polytetrafluoroethylene, polyetheretherketone, and polyphenylene sulfide.

5. The mandrel according to any one of claims 1 to 4, characterized in that The material of the bottom plate, the material of the top cover and the material of the cylindrical frame are the same.

6. The mandrel according to any one of claims 1 to 5, characterized in that The bottom plate and the cylindrical frame are an integrated structure; And / or, the top cover and the cylindrical frame are connected by bonding or threading.

7. The mandrel according to any one of claims 1 to 6, characterized in that The shape of the hollow area of the hollow structure includes at least one of polygonal, circular, elliptical, and irregular shapes; And / or, the core rod is a cylindrical core rod.

8. A battery, characterized in that: include: shell; The mandrel according to any one of claims 1 to 7, wherein the mandrel is located in the housing; A wound battery cell, comprising a positive electrode sheet, a separator and a negative electrode sheet, the wound battery cell being located in the housing and wrapped around the outside of the cylindrical skeleton of the core rod; A first electrolyte is stored in the core rod, and a second electrolyte is stored outside the core rod. The first electrolyte and the second electrolyte contain the same additive, and the concentration of the additive in the first electrolyte is greater than the concentration of the additive in the second electrolyte.

9. The battery according to claim 8, characterized in that The additive includes at least one of vinylene carbonate, fluoroethylene carbonate, 1,3-propane sultone, lithium difluorophosphate, and lithium bis(oxalatoborate).

10. The battery according to claim 8 or 9, characterized in that The battery is a cylindrical battery.

11. An electrical device, characterized in that: A battery comprising the battery according to any one of claims 8 to 10.

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