Core structure for preventing short circuit at positive plate inlet and battery comprising same

Abstract

The utility model provides a core structure for preventing short circuit at a positive plate inlet and a battery comprising the core structure. The core structure comprises a negative plate, a first diaphragm, a positive plate, a second diaphragm and a negative plate wound for a second circle which are sequentially laminated from inside to outside, the feeding end of the first diaphragm exceeds the feeding end of the negative plate, and the exceeding part is reversely folded to one side of the positive plate; the feeding end of the second diaphragm exceeds the winding end of the negative plate wound by the second circle, and the exceeding part is reversely folded to the other side of the positive plate; the reflexed point of the first diaphragm and the reflexed point of the second diaphragm respectively exceed the plate inlet end of the negative plate and the winding end of the negative plate wound by the second circle; and the sheet inlet end of the positive plate, the reflexed point of the first diaphragm and the reflexed point of the second diaphragm are arranged in a staggered manner. According to the utility model, the problem of short circuit caused by extrusion of the diaphragm due to deformation at the positive electrode sheet inlet of the roll core in the use process of the 18650 cylindrical battery is solved, and the short circuit phenomenon at the positive electrode sheet inlet can be prevented.

Description

Technical Field

[0001] The utility model belongs to the technical field of battery core winding structure design, and relates to a core structure for preventing a short circuit at a positive electrode entry point and a battery comprising the core structure. Background Art

[0002] When lithium batteries are in use, due to long-term use, the negative and positive electrodes inside the lithium batteries will expand, shrink and deform. With the development of high-energy density materials, silicon-containing materials are added to the negative electrodes of existing 18650 batteries, and the expansion rate of the winding core increases. This will increase the risk of internal short circuits due to expansion force during use, and then cause battery failure, resulting in the battery being unable to be used for a long time, shortening the use time of lithium batteries, and causing resource loss. The battery fails due to a short circuit, and it does not maximize the service life of the lithium battery itself.

[0003] The prior art solution discloses a battery roll core, comprising a roll core body having a hollow inner hole, the roll core body comprising a first diaphragm, a negative electrode sheet, a second diaphragm and a positive electrode sheet which are stacked and wound in sequence, the positive electrode sheet comprising a positive metal substrate, a positive electrode ear and a positive electrode coating coated on the positive metal substrate, the negative electrode sheet comprising a negative electrode substrate, a negative electrode ear and a negative electrode coating coated on the negative metal substrate, at least two positive electrode ears and two negative electrode ears are provided, and each positive electrode ear is located on the same side of the hollow inner hole along the radial direction of the roll core body, and each negative electrode ear is located on the same side of the hollow inner hole along the radial direction of the roll core body, each positive electrode ear is integrally formed with the positive metal substrate, and each negative electrode ear is integrally formed with the negative metal substrate.

[0004] The prior art solution also discloses a method for forming a core, wherein the core includes a diaphragm, a positive electrode sheet and a negative electrode sheet. The forming method includes the following steps: stacking the positive electrode sheet and the negative electrode sheet on the diaphragm through a stacking assembly, and then folding the diaphragm stacked with the positive electrode sheet and the negative electrode sheet through a folding assembly to form a core, and finally assembling four cores into a four-core lithium battery.

[0005] The prior art solution also discloses a method for making a battery roll core and a battery roll core. The method for making a battery roll core includes the following steps: providing a negative electrode current collector, a positive electrode current collector and at least two separators, coating the negative electrode current collector with a negative electrode slurry, and forming at least two convex portions on at least one side of the negative electrode current collector with the negative electrode slurry, and distributing two adjacent convex portions at intervals along the extension direction of the negative electrode current collector to obtain a negative electrode sheet, and coating the positive electrode slurry on the positive electrode current collector to obtain a positive electrode sheet; stacking the positive electrode sheet, the separator, the negative electrode sheet and the separator on each other, winding the first end of the positive electrode sheet to form a flat roll core, and making the convex portions cover the arc-shaped structure surface of the roll core on the negative electrode sheet.

[0006] However, when preparing 18650 cylindrical batteries, the core structure is a single-layer diaphragm. During the cycle or when subjected to force compression, the core positive electrode entry point deforms, punctures the diaphragm, and the positive and negative electrodes come into contact, resulting in a short circuit. In mild cases, there is a voltage drop; in severe cases, there is a fire and explosion. Therefore, it is urgent to design and develop a core structure that prevents short circuits at the positive electrode entry point to overcome the defects of the existing technology and meet the needs of practical applications. Utility Model Content

[0007] In view of the deficiencies in the prior art, the purpose of the utility model is to provide a core structure for preventing short circuit at the positive electrode entry point and a battery comprising the same. In the utility model, the core structure for the positive electrode entry point is specifically designed to solve the problem of short circuit caused by deformation and squeezing of the diaphragm at the positive electrode entry point of the rolled core during the use of 18650 cylindrical batteries; the problem of low voltage during the use of the battery cell when it is used to form a Pack is solved, and the occurrence of short circuit at the positive electrode entry point can be effectively prevented, and the problem of battery failure caused by non-material loss is solved. The structure is simple and suitable for promotion.

[0008] To achieve this purpose, the utility model adopts the following technical solutions:

[0009] In a first aspect, the utility model provides a core structure for preventing a short circuit at a positive electrode entry, the core structure comprising a negative electrode sheet, a first separator, a positive electrode sheet, a second separator, and the negative electrode sheet wound in a second circle, which are sequentially stacked from the inside to the outside;

[0010] The entry end of the first diaphragm exceeds the entry end of the negative electrode sheet, and the exceeding part is folded back to one side of the positive electrode sheet;

[0011] The entry end of the second separator exceeds the winding end of the negative electrode sheet wound in the second turn, and the exceeding part is folded back to the other side of the positive electrode sheet;

[0012] The inflection point of the first separator and the inflection point of the second separator are respectively beyond the entry end of the negative electrode sheet and the winding end of the negative electrode sheet wound for the second turn;

[0013] The entry end of the positive electrode sheet and the inflection point of the first diaphragm and the inflection point of the second diaphragm are all arranged in a staggered manner.

[0014] In the utility model, the core structure of the positive electrode entry is specifically designed to solve the problem of deformation and squeezing of the diaphragm to cause short circuit during the use of 18650 cylindrical batteries; the problem of low voltage during the use of the battery cell when the pack is composed is solved, and the occurrence of short circuit at the positive electrode entry can be effectively prevented, and the problem of battery failure caused by non-material loss is solved. The structure is simple and suitable for promotion.

[0015] It should be noted that the specific thickness and material of the positive and negative electrode sheets are not particularly limited in the present invention, and those skilled in the art can make adaptive adjustments according to actual conditions. The positive electrode sheet can be composed of the positive electrode main material NCM811, a conductive agent and a binder, and the negative electrode sheet is composed of the main materials graphite + silicon carbon, a conductive agent and a binder. In addition, due to the folding of the diaphragm, both sides of the positive electrode sheet are double-layer diaphragms. Increasing the thickness of the diaphragm here can increase the puncture resistance of the diaphragms on both sides of the positive electrode entry when the core of the winding core is stressed, effectively preventing the diaphragm from being deformed and squeezed at the entry during use, resulting in diaphragm damage.

[0016] It should be noted that the present invention does not impose any special limitation on the folding directions of the first diaphragm and the second diaphragm. The folding directions of the two diaphragms may be the same or different, and those skilled in the art may make adaptive adjustments according to actual conditions.

[0017] It should be noted that the "sheet entry end" in the present invention refers to the initial position of each component on the entry winding core, and the winding end refers to the starting end facing the winding side.

[0018] It should be noted that the core structure in the present invention refers to the structure of the positive electrode sheet, the negative electrode sheet and the separator at the winding point, and the specific winding method of the core structure includes:

[0019] When a normal 18650 core is wound, the first diaphragm and the second diaphragm are aligned and wound together with the winding needle, the negative electrode sheet is inserted into the winding machine, and finally the positive electrode sheet is inserted. When the first diaphragm and the second diaphragm are pre-wound against each other, the diaphragms will be folded back, and the folded two layers of diaphragms are randomly distributed and have no contact with the positive electrode sheet. However, in the utility model, the folding position and folding length of the first diaphragm and the second diaphragm are adjusted, and the second diaphragm is folded back between the negative electrode sheet and the positive electrode sheet wound for the second turn, and the first diaphragm is folded back between the negative electrode sheet and the positive electrode sheet, and the two layers of diaphragms are distributed on both sides of the positive electrode. The length of the pre-wound fold of the first diaphragm and the second diaphragm can be adjusted to 10 mm, and at this time there are double layers of diaphragms on both sides of the positive electrode sheet.

[0020] As a preferred technical solution of the utility model, the folded length of the first diaphragm is 7 to 8 mm, for example, it can be 7 mm, 7.1 mm, 7.2 mm, 7.3 mm, 7.4 mm, 7.5 mm, 7.6 mm, 7.7 mm, 7.8 mm, 7.9 mm, 8 mm, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0021] Preferably, the folded length of the second diaphragm is 10-11 mm, for example, it can be 10 mm, 10.1 mm, 10.2 mm, 10.3 mm, 10.4 mm, 10.5 mm, 10.6 mm, 10.7 mm, 10.8 mm, 10.9 mm, 11 mm, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0022] In the utility model, the folded length of the first diaphragm is 7-8 mm and the folded length of the second diaphragm is 10-11 mm. This is because within this size range, the folded lengths of the first diaphragm and the second diaphragm can exceed the position where the positive electrode enters the sheet. If it is not within this limited range, the positive electrode entry position cannot reach the phenomenon of having two layers of diaphragms on each side, and the technical requirement cannot be achieved.

[0023] As a preferred technical solution of the utility model, the negative electrode sheet is a graphite carbon silicon negative electrode sheet.

[0024] As a preferred technical solution of the present invention, the first diaphragm is the same as the second diaphragm.

[0025] It should be noted that in the present invention, the first diaphragm and the second diaphragm are the same, which means that the material, size and other related parameters of the first diaphragm are exactly the same as those of the second diaphragm.

[0026] As a preferred technical solution of the present utility model, the first diaphragm is a polyethylene diaphragm.

[0027] As a preferred technical solution of the present invention, the thickness of the first diaphragm is 16 to 20 μm, for example, it can be 16 μm, 16.5 μm, 17 μm, 17.5 μm, 18 μm, 18.5 μm, 19 μm, 19.5 μm, 20 μm, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0028] The thickness of the first diaphragm in the present invention is 16 to 20 μm because within this size range, the prepared core structure meets the 18650 battery standard. Too thin a thickness is not conducive to battery safety performance, and too thick a thickness affects the core diameter.

[0029] As a preferred technical solution of the utility model, the length of the inflection point of the first diaphragm exceeding the entry end of the negative electrode sheet by 7 to 8 mm, for example, it can be 7 mm, 7.1 mm, 7.2 mm, 7.3 mm, 7.4 mm, 7.5 mm, 7.6 mm, 7.7 mm, 7.8 mm, 7.9 mm, 8 mm, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0030] As a preferred technical solution of the utility model, the length of the inflection point of the second diaphragm exceeding the entry end of the negative electrode sheet by 10 to 11 mm, for example, it can be 10 mm, 10.1 mm, 10.2 mm, 10.3 mm, 10.4 mm, 10.5 mm, 10.6 mm, 10.7 mm, 10.8 mm, 10.9 mm, 11 mm, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0031] As a preferred technical solution of the utility model, the distance between the entry end of the positive electrode sheet and the inflection point of the first diaphragm is 5 to 6 mm, for example, it can be 5mm, 5.1mm, 5.2mm, 5.3mm, 5.4mm, 5.5mm, 5.6mm, 5.7mm, 5.8mm, 5.9mm, 6mm, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0032] In the utility model, the distance between the entry end of the positive electrode sheet and the inflection point of the first diaphragm is 5 to 6 mm. This is because within this size range, there is a margin for the existence of double-layer diaphragms on both sides of the positive electrode entry. If it is not within this range, the technical solution will fail. This is because there are fluctuations when the equipment implements the solution.

[0033] In a second aspect, the utility model provides a battery, comprising the core structure described in the first aspect.

[0034] It should be noted that the specific assembly form, material and size of the battery are not particularly limited in the present invention, and those skilled in the art can make adaptive adjustments according to actual conditions. Among them, the battery model can be a 18650 cylindrical battery, and the battery made of the above chip structure in the present invention has a higher pass rate in the extrusion test and the heavy object impact test in the safety test items compared to the battery with the traditional core structure.

[0035] Compared with the prior art, the beneficial effects of the utility model are:

[0036] In the utility model, the core structure of the positive electrode entry is specifically designed to solve the problem of deformation and squeezing of the diaphragm to cause short circuit during the use of 18650 cylindrical batteries; the problem of low voltage during the use of the battery cell when the pack is composed is solved, and the occurrence of short circuit at the positive electrode entry can be effectively prevented, and the problem of battery failure caused by non-material loss is solved. The structure is simple and suitable for promotion. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 A schematic diagram of a core structure for preventing short circuit at the positive electrode entry point provided by a specific embodiment of the utility model;

[0038] Figure 2 A schematic diagram of the winding of a core structure for preventing a short circuit at the positive electrode entry point provided by a specific embodiment of the utility model;

[0039] Among them, 1-negative electrode sheet; 2-first separator; 3-positive electrode sheet; 4-second separator; 5-negative electrode sheet wound for the second time. DETAILED DESCRIPTION

[0040] It should be understood that, in the description of the present utility model, the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, which is only for the convenience of describing the present utility model and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present utility model. In addition, the terms "first", "second", etc. are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of the present utility model, unless otherwise specified, "multiple" means two or more.

[0041] It should be noted that in the description of the present invention, unless otherwise clearly specified and limited, the terms "disposed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood by specific circumstances.

[0042] The technical solution of the utility model is further explained below with reference to the accompanying drawings and through specific implementation methods.

[0043] In a specific embodiment, the utility model provides a core structure for preventing short circuit at the positive electrode entry, such as Figure 1 and Figure 2As shown, the core structure includes a negative electrode sheet 1, a first separator 2, a positive electrode sheet 3, a second separator 4 and a negative electrode sheet 5 wound for the second time, which are stacked in sequence from the inside to the outside; the entry end of the first separator 2 exceeds the entry end of the negative electrode sheet 1, and the exceeding part is folded back to one side of the positive electrode sheet 3; the entry end of the second separator 4 exceeds the winding end of the negative electrode sheet 5 wound for the second time, and the exceeding part is folded back to the other side of the positive electrode sheet 3; the inflection point of the first separator 2 and the inflection point of the second separator 4 exceed the entry end of the negative electrode sheet 1 and the winding end of the negative electrode sheet 5 wound for the second time respectively; the entry end of the positive electrode sheet 3 and the inflection point of the first separator 2 and the inflection point of the second separator 4 are all staggered.

[0044] In the utility model, the core structure of the positive electrode entry is specifically designed to solve the problem of deformation and squeezing of the diaphragm to cause short circuit during the use of 18650 cylindrical batteries; the problem of low voltage during the use of the battery cell when the pack is composed is solved, and the occurrence of short circuit at the positive electrode entry can be effectively prevented, and the problem of battery failure caused by non-material loss is solved. The structure is simple and suitable for promotion.

[0045] It should be noted that the present invention does not specifically limit the specific thickness and material of the positive electrode sheet 3 and the negative electrode sheet 1. Those skilled in the art can make adaptive adjustments according to actual conditions. The positive electrode sheet 3 can be composed of the positive electrode main material NCM811, a conductive agent and a binder, and the negative electrode sheet is composed of the main material graphite + silicon carbon, a conductive agent and a binder. In addition, due to the folding of the diaphragm, both sides of the positive electrode sheet 3 are double-layer diaphragms. Increasing the thickness of the diaphragm here can increase the puncture resistance of the diaphragms on both sides of the positive electrode entry when the core of the winding core is stressed, effectively preventing the diaphragm from being deformed and squeezed at the entry during use, resulting in diaphragm damage.

[0046] It should be noted that the present invention does not impose any special limitation on the folding directions of the first diaphragm 2 and the second diaphragm 4 . The folding directions of the two diaphragms can be the same or different, and those skilled in the art can make adaptive adjustments according to actual conditions.

[0047] It should be noted that the core structure in the present invention refers to the structure of the positive electrode sheet 3, the negative electrode sheet and the separator at the winding point, and the specific winding method of the core structure includes:

[0048] When a normal 18650 winding core is wound, the first diaphragm 2 and the second diaphragm 4 are aligned and wound together with the winding needle, the negative electrode sheet is inserted into the winding machine, and finally the positive electrode sheet 3 is inserted. The first diaphragm 2 and the second diaphragm 4 will be folded when they are pre-rolled, and the folded two layers of diaphragms are randomly distributed and have no contact with the positive electrode sheet. However, in the utility model, the folding position and folding length of the first diaphragm 2 and the second diaphragm 4 are adjusted, and the second diaphragm 4 is folded back between the negative electrode sheet 5 and the positive electrode sheet 3 wound for the second turn, and the first diaphragm 2 is folded back between the negative electrode sheet 1 and the positive electrode sheet 3, and the two layers of diaphragms are distributed on both sides of the positive electrode; the length of the pre-rolled fold of the first diaphragm 2 and the second diaphragm 4 is adjusted to 10 mm, and at this time there are double layers of diaphragms on both sides of the positive electrode sheet 3.

[0049] Furthermore, the folded length of the first diaphragm 2 is 7 to 8 mm, for example, it can be 7 mm, 7.1 mm, 7.2 mm, 7.3 mm, 7.4 mm, 7.5 mm, 7.6 mm, 7.7 mm, 7.8 mm, 7.9 mm, 8 mm, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0050] Furthermore, the folded length of the second diaphragm 4 is 10-11 mm, for example, it can be 10 mm, 10.1 mm, 10.2 mm, 10.3 mm, 10.4 mm, 10.5 mm, 10.6 mm, 10.7 mm, 10.8 mm, 10.9 mm, 11 mm, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0051] Furthermore, the first negative electrode sheet 1 is a graphite carbon silicon negative electrode sheet.

[0052] Furthermore, the first diaphragm 2 and the second diaphragm 4 are identical.

[0053] It should be noted that in the present invention, the first diaphragm 2 and the second diaphragm 4 are the same, which means that the material, size and other related parameters of the first diaphragm 2 are exactly the same as those of the second diaphragm 4 .

[0054] Furthermore, the first diaphragm 2 is a polyethylene diaphragm.

[0055] Furthermore, the thickness of the first diaphragm 2 is 16 to 20 μm, for example, it can be 16 μm, 16.5 μm, 17 μm, 17.5 μm, 18 μm, 18.5 μm, 19 μm, 19.5 μm, 20 μm, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0056] Furthermore, the length of the inflection point of the first diaphragm 2 beyond the entry end of the negative electrode sheet 1 is 7 to 8 mm, for example, it can be 7 mm, 7.1 mm, 7.2 mm, 7.3 mm, 7.4 mm, 7.5 mm, 7.6 mm, 7.7 mm, 7.8 mm, 7.9 mm, 8 mm, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0057] Furthermore, the length of the inflection point of the second separator 4 beyond the entry end of the negative electrode sheet 1 is 10-11 mm, for example, it can be 10 mm, 10.1 mm, 10.2 mm, 10.3 mm, 10.4 mm, 10.5 mm, 10.6 mm, 10.7 mm, 10.8 mm, 10.9 mm, 11 mm, etc., but it is not limited to the listed values, and other values ​​not listed in the numerical range are also applicable. .

[0058] Furthermore, the distance between the entry end of the positive electrode sheet 3 and the inflection point of the first diaphragm 2 is 5 to 6 mm, for example, it can be 5 mm, 5.1 mm, 5.2 mm, 5.3 mm, 5.4 mm, 5.5 mm, 5.6 mm, 5.7 mm, 5.8 mm, 5.9 mm, 6 mm, etc., but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0059] In another specific embodiment, the utility model provides a battery, and the battery includes the core structure mentioned above.

[0060] Example 1

[0061] The utility model provides a core structure for preventing short circuit at the positive electrode entry point, wherein:

[0062] The core structure includes a negative electrode sheet 1, a first separator 2, a positive electrode sheet 3, a second separator 4 and a negative electrode sheet 5 wound for the second time, which are stacked in sequence from the inside to the outside; the entry end of the first separator 2 exceeds the entry end of the negative electrode sheet 1, and the exceeding part is folded back to one side of the positive electrode sheet 3; the entry end of the second separator 4 exceeds the winding end of the negative electrode sheet 5 wound for the second time, and the exceeding part is folded back to the other side of the positive electrode sheet 3; the inflection point of the first separator 2 and the inflection point of the second separator 4 exceed the entry end of the negative electrode sheet 1 and the winding end of the negative electrode sheet 5 wound for the second time respectively; the entry end of the positive electrode sheet 3 and the inflection point of the first separator 2 and the inflection point of the second separator 4 are all staggered.

[0063] The folded length of the first diaphragm 2 is 7 mm, and the folded length of the second diaphragm 4 is 10 mm.

[0064] The first negative electrode sheet 1 is a graphite carbon silicon negative electrode sheet.

[0065] The first diaphragm 2 is the same as the second diaphragm 4, and the first diaphragm 2 is a polyethylene diaphragm.

[0066] The thickness of the first separator 2 is 18 μm, the length of the inflection point of the first separator 2 beyond the entry end of the negative electrode sheet 1 is 8 mm, and the length of the inflection point of the second separator 4 beyond the entry end of the negative electrode sheet 1 is 11 mm. The distance between the entry end of the positive electrode sheet 3 and the inflection point of the first separator 2 is 5 mm.

[0067] In the present invention, a PACK cycle test was conducted on the battery having the core structure of the present invention. The cycle data was found to be significantly better than the PACK composed of batteries with a traditional electrode sheet entry structure, that is, the traditional electrode sheet entry does not have the adjustment of the diaphragm folding direction and length, and the length is not corresponding to the positive electrode entry. This allows the battery in the present invention to still have excellent performance after a long period of practical use in the battery pack, and the service life of the battery pack is 4 times longer than that of a normal winding core, as shown in Table 1 below.

[0068] Table 1 Test results

[0069]

[0070] In summary, the utility model solves the problem of deformation and squeezing of the diaphragm causing short circuit at the positive electrode entry point of the rolled core during the use of 18650 cylindrical batteries through the specific design of the core structure of the positive electrode entry point; solves the problem of low voltage during the use of the battery cell when it is used to form a Pack package, can effectively prevent the occurrence of short circuit at the positive electrode entry point, and solves the problem of battery failure caused by non-material loss. The structure is simple and suitable for promotion.

[0071] The above description is only a specific implementation method of the present utility model, but the protection scope of the present utility model is not limited thereto. Technicians in the relevant technical field should understand that any changes or substitutions that can be easily thought of by technicians in the relevant technical field within the technical scope disclosed in the present utility model fall within the protection scope and disclosure scope of the present utility model.

Claims

1. A core structure for preventing short circuit at the positive electrode entry, characterized in that: The core structure includes a negative electrode sheet, a first separator, a positive electrode sheet, a second separator, and the negative electrode sheet wound in a second circle, which are stacked in sequence from the inside to the outside; The entry end of the first diaphragm exceeds the entry end of the negative electrode sheet, and the exceeding part is folded back to one side of the positive electrode sheet; The entry end of the second separator exceeds the winding end of the negative electrode sheet wound in the second turn, and the exceeding part is folded back to the other side of the positive electrode sheet; The inflection point of the first separator and the inflection point of the second separator are respectively beyond the entry end of the negative electrode sheet and the winding end of the negative electrode sheet wound for the second turn; The entry end of the positive electrode sheet and the inflection point of the first diaphragm and the inflection point of the second diaphragm are all arranged in a staggered manner.

2. The core structure for preventing short circuit at the positive electrode entry point according to claim 1, characterized in that: The inflection length of the first diaphragm is 7 to 8 mm; The inflection length of the second diaphragm is 10-11 mm.

3. The core structure for preventing short circuit at the positive electrode entry point according to claim 2, characterized in that: The negative electrode sheet is a graphite carbon silicon negative electrode sheet.

4. The core structure for preventing short circuit at the positive electrode entry point according to claim 1, characterized in that: The first diaphragm and the second diaphragm are identical.

5. The core structure for preventing short circuit at the positive electrode entry point according to claim 4, characterized in that: The first diaphragm is a polyethylene diaphragm.

6. The core structure for preventing short circuit at the positive electrode entry point according to claim 4 or 5, characterized in that: The thickness of the first separator is 16-20 μm.

7. The core structure for preventing short circuit at the positive electrode entry point according to claim 1, characterized in that: The length of the inflection point of the first separator beyond the entry end of the negative electrode sheet is 7 to 8 mm.

8. The core structure for preventing short circuit at the positive electrode entry point according to claim 1, characterized in that: The length of the inflection point of the second separator beyond the entry end of the negative electrode sheet is 10 to 11 mm.

9. The core structure for preventing short circuit at the positive electrode entry point according to claim 1, characterized in that: The distance between the entry end of the positive electrode sheet and the inflection point of the first separator is 5 to 6 mm.

10. A battery, characterized in that: The battery comprises the core structure according to any one of claims 1 to 9.

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