Cylindrical roll core and cylindrical lithium ion battery

Abstract

The utility model provides a cylindrical roll core and cylindrical lithium ion battery relates to battery technical field, cylindrical roll core includes roll core, the lateral side of roll core is equipped with the through hole that runs through along its radial direction, roll core includes positive pole piece, negative pole piece and diaphragm, positive pole piece and negative pole piece are respectively arranged the both sides of diaphragm, the positive pole piece is provided with a positive pole hole, the negative pole piece is provided with a negative pole hole, and the diaphragm is provided with a diaphragm hole; the positions of the positive electrode holes, the negative electrode holes and the diaphragm holes are in one-to-one correspondence; the positive pole piece, the negative pole piece and the diaphragm are wound in the circumferential direction of the winding needle to form the winding core, through holes are formed among the positive pole hole, the negative pole hole and the diaphragm hole which are located in the same straight line, and the cylindrical winding core achieves timely liquid supplementing in the later period of circulation through a reserved center through hole structure, and the problem of liquid shortage in the middle is solved; meanwhile, heat accumulation in the middle of the battery is reduced, and the battery performance is improved; and an electrolyte infiltration channel is additionally arranged, so that the production infiltration efficiency is improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to battery technology field especially relates to a cylindrical winding core and cylindrical lithium ion battery. BACKGROUND

[0002] The cylindrical winding core is a key component in the field of battery manufacturing, and is widely used in cylindrical lithium batteries. It plays an important role in electric vehicles, portable electronic devices and many other fields. For example, the cylindrical winding core structure disclosed in CN222029277U includes: a pole piece structure, the pole piece structure includes a dressing area and a tab area extending from the top of the dressing area; the dressing area extends along the length direction; the tab area includes multiple groups of tab positions, each group of tab positions is arranged at intervals, the height dimension of the tab position in the next group is higher than that of the tab position in the previous group, the pole piece structure is wound into a cylindrical shape along the length direction, and each group of tab positions is located in the same side half circle area of the top surface of the cylinder after winding, forming a tab mirror image symmetric structure.

[0003] The current cylindrical battery winding structure has high compactness, which can easily cause the middle part of the battery to swell after cycling, the electrolyte is squeezed out, causing a lack of electrolyte in the middle part, poor lithium ion transmission and embedding, and lithium precipitation phenomenon, which can accelerate the attenuation of battery life and cause short circuit and safety risks. At the same time, the infiltration process of the battery after liquid injection is only carried out through the center hole and the two sides, which takes a long time and can easily cause interface abnormalities. UTILITY MODEL CONTENTS

[0004] Therefore, the utility model provides a cylindrical winding core and cylindrical lithium ion battery, which realizes timely liquid supplement in the later cycle stage through the reserved center through hole structure, and relieves the problem of lack of electrolyte in the middle part. At the same time, the structure also helps to reduce the heat accumulation in the middle part of the battery, reduce the high temperature side reaction of the electrolyte, and improve the battery performance. In addition, the through hole structure also increases the infiltration channel of the electrolyte, and improves the production infiltration efficiency.

[0005] The technical scheme of the utility model is as follows: the utility model provides a cylindrical winding core, which is characterized by comprising a winding core, a through hole penetrating along the radial direction of the winding core is formed in the side surface of the winding core,

[0006] The winding core comprises a positive pole piece, a negative pole piece and a separator, wherein,

[0007] The positive pole piece and the negative pole piece are arranged on the two sides of the separator, the positive pole piece is provided with a positive pole hole, the negative pole piece is provided with a negative pole hole, and the separator is provided with a separator hole; the positions of the positive pole hole, the negative pole hole and the separator hole are arranged one by one in correspondence;

[0008] The positive pole piece, the negative pole piece and the separator are wound along the circumference of the winding needle to form the winding core, and the through hole is formed between the positive pole hole, the negative pole hole and the separator hole located at the same straight line position.

[0009] Preferably, in the above technical solution, the number of through holes is multiple, and at least one of the through holes is located at the middle of the axial direction of the core and is arranged at intervals with adjacent through holes.

[0010] Preferably, in the above technical solution, the relative position interval between adjacent through holes is 20-30 mm.

[0011] Preferably, in the above technical solution, the diameter of the positive electrode hole is larger than the diameter of the negative electrode hole, and the diameter of the negative electrode hole is larger than the diameter of the diaphragm hole.

[0012] Preferably, in the above technical solution, the diameter of the negative electrode hole is at least 1-3 mm larger than the diameter of the diaphragm hole, and the diameter of the diaphragm hole is greater than or equal to 0.6 mm.

[0013] Preferably, in the above technical solution, the negative electrode tab is provided with a negative electrode material layer, and the negative electrode material layer is coated in the area outside the surface of the diaphragm hole projected on the negative electrode tab.

[0014] Preferably, in the above technical solution, the diameter of the positive electrode hole is at least 1-3 mm larger than the diameter of the negative electrode hole, and the diameter of the positive electrode hole is less than or equal to 5 mm.

[0015] Preferably, in the above technical solution, the positive electrode tab is provided with a positive electrode material layer, and the positive electrode material layer is coated in the area outside the surface of the negative electrode hole projected on the positive electrode tab.

[0016] Preferably, in the above technical solution, the hole spacing between the multiple positive electrode holes, negative electrode holes and diaphragm holes located on the same straight line satisfies: d n =n·2πh, d n is the hole spacing between the nth and n+1 holes, n is the serial number of the hole, and h is the thickness increased by one winding of the core.

[0017] In a second aspect, the utility model also provides a cylindrical lithium ion battery which comprises the cylindrical core.

[0018] The cylindrical core and the cylindrical lithium ion battery of the utility model have the following beneficial effects compared with the prior art:

[0019] (1) The through hole structure is arranged at the center of the side surface of the core to reduce the heat accumulation in the middle of the battery, reduce the high-temperature side reaction of the electrolyte, improve the overall performance of the battery, and supplement the liquid through the through hole in the later stage of the battery cycle, alleviate the liquid shortage problem in the middle, and prolong the service life of the battery.

[0020] (2) By taking the axial direction center point of the core as the reference point, multiple through holes are opened to both sides at intervals, which can accelerate the infiltration process of the electrolyte, make the flow path of the electrolyte in the battery more smooth, improve the infiltration speed, ensure the uniform distribution of electrolyte in each part of the battery, thereby improving the production efficiency of the battery; (3) By setting the aperture ratio relationship of the positive electrode hole, the negative electrode hole and the diaphragm hole and the coating position of the material layer, the flow path and infiltration speed of the electrolyte are optimized, the smooth flow and uniform distribution of the electrolyte in the battery are ensured, and the risk of lithium precipitation and short circuit is avoided, thereby significantly improving the performance and safety of the battery;

[0021] (4) By accurately calculating the positions of the positive electrode hole, the negative electrode hole and the diaphragm hole at the hole opening position before winding, one-to-one correspondence can be ensured during the winding process, an effective through hole structure is formed, the smooth flow of the electrolyte and the rapid transmission of ions are facilitated, and the performance of the battery is improved. BRIEF DESCRIPTION OF DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or prior art description will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0023] Figure 1 It is a perspective view of the cylindrical core of the present application;

[0024] Figure 2 It is a perspective view of the pole piece and diaphragm covering structure of the cylindrical core of the present application;

[0025] Figure 3 It is a cross-sectional view of the pole piece and diaphragm covering structure of the cylindrical core of the present application;

[0026] Figure 4 It is a schematic view of the hole opening structure on the pole piece and diaphragm of the cylindrical core of the present application. DETAILED DESCRIPTION

[0027] The technical solutions in the embodiments of the present application will be described in detail below. Obviously, the described embodiments are only some embodiments of the present application, not all embodiments. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0028] As Figures 1-4As shown, the cylindrical core of the utility model, including core 1, the lateral surface of core 1 is provided with the through hole 100 along its radial direction direction.

[0029] Need to explain, in the embodiment, by the through hole 100 along the radial direction direction of the lateral surface of core 1 is set up, and the through hole 100 is located at the axial direction intermediate of core 1, so that the battery in the process of charge and discharge, middle part is easy to produce heat collection, the existence of through hole 100 provides the passage of heat dissipation, helps to reduce the temperature of the middle part of battery, thereby reducing the electrolyte side reaction caused by high temperature, and then improve the overall performance of battery, simultaneously, the battery in the process of cyclic use, middle part electrolyte can be extruded due to expansion, lead to middle part liquid deficiency, through hole 100 as liquid supplement channel, can be supplemented by the hole after battery cycle, thereby alleviating middle part liquid deficiency problem, prolong the service life of battery.

[0030] It can be understood that, by the lateral surface center of core 1 is set up through hole 100, can reduce the heat collection of the middle part of battery and reduce electrolyte high temperature side reaction, improve the overall performance of battery, and, in the later period of battery cycle, can be supplemented by the hole, thereby alleviating middle part liquid deficiency problem, prolong the service life of battery.

[0031] The core 1 in the embodiment includes a positive electrode sheet 11, a negative electrode sheet 12 and a separator 13, wherein the positive electrode sheet 11 and the negative electrode sheet 12 are arranged on both sides of the separator 13, a plurality of positive electrode holes 110 are formed on the positive electrode sheet 11, a plurality of negative electrode holes 120 are formed on the negative electrode sheet 12, and a plurality of separator holes 130 are formed on the separator 13; the positions of the positive electrode holes 110, the negative electrode holes 120 and the separator holes 130 are one-to-one corresponding; the positive electrode sheet 11, the negative electrode sheet 12 and the separator 13 are circumferentially wound to form the core 1, and the positive electrode holes 110, the negative electrode holes 120 and the separator holes 130 located at the same straight line position form the through hole 100.

[0032] It should be noted that the positive electrode sheet 11, the negative electrode sheet 12 and the separator 13 are circumferentially wound to form the core 1; during winding, the through hole 100 is formed between the plurality of positive electrode holes 110, the negative electrode holes 120 and the separator holes 130 located at the same straight line position, ensuring the alignment of the holes during winding, forming an effective through hole 100 structure, and the diameter of the positive electrode hole 110 is greater than the diameter of the negative electrode hole 120, and the diameter of the negative electrode hole 120 is greater than the diameter of the separator hole 130, ensuring that the electrolyte can smoothly pass through the through hole, while avoiding the influence of the hole diameter being too large or too small on the performance of the battery.

[0033] The infiltration speed of the electrolyte in the battery is also an important factor affecting the performance of the battery, and if the infiltration is insufficient, it may cause abnormal battery interface, thereby affecting the cycle life and safety of the battery.

[0034] In order to solve the problem of heat accumulation in the middle of the cylindrical battery and the difficulty of liquid supplementing after cycling, and optimize the infiltration speed of the electrolyte, the number of through holes 100 in the embodiment is multiple, and at least one of the through holes 100 is located at the middle of the axial direction of the winding core 1 and is arranged at intervals with the adjacent two through holes 100.

[0035] It should be noted that the existence of multiple through holes 100 provides more heat dissipation channels for the middle of the battery. During the charging and discharging process of the battery, the heat generated can be quickly dissipated through these through holes, thereby reducing the temperature of the middle of the battery and reducing the electrolyte side reaction caused by high temperature. The through holes 100 act as a liquid supplementing channel, and can be supplemented with liquid through these holes during the later stage of battery cycling. When the electrolyte in the middle of the battery is squeezed out due to expansion, the electrolyte can be supplemented in time through the through holes 100, thereby alleviating the problem of liquid deficiency in the middle and prolonging the service life of the battery.

[0036] At the same time, according to the height requirement of the winding core and considering the electrolyte infiltration speed of the pole piece, the through holes 100 are arranged at intervals on both sides of the center point of the axial direction of the winding core 1, and the direction and number of the arranged through holes 100 can be adjusted to meet the actual electrolyte infiltration speed of the pole piece.

[0037] In the embodiment, the number and position of the through holes 100 are optimized to accelerate the infiltration process of the electrolyte, make the flow path of the electrolyte in the battery more smooth, improve the infiltration speed, and ensure the uniform distribution of the electrolyte in each part of the battery, thereby improving the production efficiency of the battery.

[0038] Specifically, the relative position interval between the adjacent through holes 100 in the embodiment is 20-30 mm. The interval distance ensures that the interval between the through holes 100 is neither too large to cause poor heat dissipation and liquid supplementing effect, nor too small to affect the stability of the battery structure.

[0039] In the embodiment, the diameter of the positive electrode hole 110 is greater than the diameter of the negative electrode hole 120, and the diameter of the negative electrode hole 120 is greater than the diameter of the diaphragm hole 130.

[0040] It should be noted that when the diameter ratio relationship is abnormal, i.e. the negative electrode hole 120 is greater than the positive electrode hole 110, there is a risk of lithium precipitation, which will reduce the overall performance of the battery, greatly shorten its cycle life, and may cause safety risks such as combustion, battery swelling and even explosion. When the negative electrode hole 120 is smaller than the diaphragm hole 130 or the positive electrode hole 110 is smaller than the diaphragm hole 130, the small diameter may not be able to effectively isolate the positive and negative electrodes, causing internal short circuit of the battery.

[0041] In the embodiment, the diameter of the negative electrode hole 120 is at least 1-3 mm greater than the diameter of the diaphragm hole 130, and the diameter of the diaphragm hole 130 is ≥0.6 mm.

[0042] It should be noted that the pore diameter of the negative electrode hole 120 is at least 1-3 mm larger than the pore diameter of the diaphragm hole 130, ensuring that the electrolyte can smoothly pass through the through hole 100, while avoiding the influence of the pore diameter being too large or too small on the performance of the battery. The pore diameter of the diaphragm hole 130 is greater than or equal to 0.6 mm, ensuring the passability of the electrolyte and avoiding the electrolyte flowing poorly due to the pore diameter being too small.

[0043] In this embodiment, the negative electrode tab 12 is provided with a negative electrode material layer 121, and the negative electrode material layer 121 is coated in the area outside the surface of the negative electrode tab 12 on which the diaphragm hole 130 is projected.

[0044] It should be noted that the diaphragm hole 130 covers the projection area of the negative electrode hole 120, but the negative electrode material layer 121 is all outside the diaphragm hole 130, avoiding the direct blocking of the diaphragm hole 130 by the negative electrode active material, thereby ensuring the smooth flow of the electrolyte.

[0045] In this embodiment, the pore diameter of the positive electrode hole 110 is at least 1-3 mm larger than the pore diameter of the negative electrode hole 120, and the pore diameter of the positive electrode hole 110 is less than or equal to 5 mm.

[0046] It should be noted that the pore diameter of the positive electrode hole 110 is at least 1-3 mm larger than the pore diameter of the negative electrode hole 120, optimizing the flow path of the electrolyte, improving the infiltration speed, and ensuring that the electrolyte is evenly distributed in each part of the battery. In addition, the pore diameter of the positive electrode hole 110 is less than or equal to 5 mm, because a too large positive electrode opening may affect the battery capacity; if the positive electrode hole 110 is too large, it will result in a decrease in the positive electrode active material, thereby reducing the battery capacity.

[0047] In this embodiment, the positive electrode tab 11 is provided with a positive electrode material layer 111, and the positive electrode material layer 111 is coated in the area outside the surface of the positive electrode tab 11 on which the negative electrode hole 120 is projected.

[0048] It should be noted that the positive electrode hole 110 covers the negative electrode hole 120, but the positive electrode material layer 111 is all outside the negative electrode hole, optimizing the flow path of the electrolyte and improving the infiltration speed.

[0049] In this embodiment, the hole spacing between the plurality of positive electrode holes 110, negative electrode holes 120 and diaphragm holes 130 located on the same straight line all satisfy: d n = n·2πh, d n is the hole spacing between the nth and n+1th holes, n is the serial number of the hole, and h is the thickness increased by one winding of the winding core.

[0050] Before winding, this structure needs to be punched before winding, and then the positive electrode tab 11, the negative electrode tab 12 and the diaphragm 13 need to be punched respectively to form the positive electrode hole 110, the negative electrode hole 120 and the diaphragm hole 130. In order to ensure the alignment and coating effect of the holes after winding, the spacing of the holes needs to be calculated.

[0051] The winding structure is an Archimedes spiral structure, as the number of cladding layers increases, the hole position is affected by the thickness, the hole spacing increases, and the hole spacing needs to be calculated according to the following formula: d n = n·2πh.

[0052] In the embodiment, it is assumed that the radius increases by a thickness h = 0.1 mm per winding, the length of the pole piece is L = 1000 mm, the width W = 95 mm, and the diameter of the winding needle is 3 mm, wherein the positive pole piece 11, the negative pole piece 12 and the separator 13 are wound around the winding needle to form a multi-layer cylinder, wherein,

[0053] The radius of the nth layer is r n = r0 + n·h = 1.5 + 0.1n, r0 is the radius of the winding needle;

[0054] The circumference of the nth layer is C n = 2πn = 2π(1.5 + 0.1n);

[0055] The circumference increment is ΔC = C n+1 -C n = 2πh;

[0056] Wherein, the radius increases by a thickness h per winding, and the hole spacing d must be an integer multiple of the circumference increment ΔC to align the holes of each layer after winding, and then the hole spacing formula d n = n·2πh, n is a positive integer.

[0057] In a second aspect, the utility model also provides a cylindrical lithium ion battery, including cylindrical winding core.

[0058] The above only describes the preferred embodiment of the utility model, and does not limit the utility model, and any modification, equivalent replacement, improvement, etc. within the spirit and principle of the utility model should be included in the protection scope of the utility model.

Claims

1. A cylindrical core, characterized by The application relates to a cylindrical core (1) comprising a through hole (100) penetrating through the side of the core (1) along the radial direction of the core (1), The core (1) comprises a positive electrode sheet (11), a negative electrode sheet (12) and a diaphragm (13), wherein, The positive electrode sheet (11) and the negative electrode sheet (12) are arranged on the two sides of the diaphragm (13), the positive electrode sheet (11) is provided with a positive electrode hole (110), the negative electrode sheet (12) is provided with a negative electrode hole (120), and the diaphragm (13) is provided with a diaphragm hole (130); the positive electrode hole (110) is arranged in one-to-one correspondence with the positions of the negative electrode hole (120) and the diaphragm hole (130). The positive electrode sheet (11), the negative electrode sheet (12) and the diaphragm (13) are wound along the circumference of the winding needle to form the core (1), and the positive electrode hole (110), the negative electrode hole (120) and the diaphragm hole (130) located at the same straight line position form the through hole (100).

2. The cylindrical core of claim 1 wherein: The number of the through holes (100) is multiple, and at least one of the through holes (100) is arranged at the middle of the axial direction of the core (1) and is spaced apart from the adjacent through hole (100).

3. The cylindrical core of claim 2 wherein: The relative position interval between the adjacent through holes (100) is 20-30 mm.

4. The cylindrical core according to any one of claims 1 to 2, wherein: The hole diameter of the positive electrode hole (110) is larger than that of the negative electrode hole (120), and the hole diameter of the negative electrode hole (120) is larger than that of the diaphragm hole (130).

5. The cylindrical core of claim 4 wherein: The hole diameter of the negative electrode hole (120) is at least 1-3 mm larger than that of the diaphragm hole (130), and the hole diameter of the diaphragm hole (130) is greater than or equal to 0.6 mm.

6. The cylindrical core of claim 4 wherein: The negative electrode sheet (12) is provided with a negative electrode material layer (121), and the negative electrode material layer (121) is coated in the area outside the surface of the negative electrode sheet (12) on which the diaphragm hole (130) is projected.

7. The cylindrical core of claim 4 wherein: The hole diameter of the positive electrode hole (110) is at least 1-3 mm larger than that of the negative electrode hole (120), and the hole diameter of the positive electrode hole (110) is less than or equal to 5 mm.

8. The cylindrical core of claim 4 wherein: The positive electrode sheet (11) is provided with a positive electrode material layer (111), and the positive electrode material layer (111) is coated in the area outside the surface of the positive electrode sheet (11) on which the negative electrode hole (120) is projected.

9. The cylindrical core of claim 4 wherein: The hole spacing between the plurality of positive electrode holes (110), the negative electrode holes (120), and the separator holes (130) located on the same straight line all satisfy: d n = n · 2πh, d n is the hole spacing between the n-th and the n+1-th holes, n is the serial number of the hole, and h is the thickness added by one winding of the winding core.

10. A cylindrical lithium-ion battery, characterized by: The application further relates to a cylindrical core comprising the cylindrical core according to any one of claims 1-9.

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