Roll core structure and lithium ion battery

Abstract

The utility model belongs to the technical field of battery production and manufacturing, and particularly relates to a roll core structure and a lithium ion battery, the roll core structure comprises a first pole piece, a second pole piece and a diaphragm, the first pole piece, the diaphragm and the second pole piece are sequentially overlapped and wound to form a roll core; one of the first pole piece and the second pole piece is provided with a welding slot position, and the surface of the other one of the first pole piece and the second pole piece is sequentially provided with an insulating layer and first insulating glue; the insulating layer and the first insulating glue cover at least one side of the welding slot position in the depth direction, the insulating layer is arranged on the surface of the first pole piece or the second pole piece, and the first insulating glue is close to the welding slot position. By optimizing the roll core structure, the internal resistance of the short circuit of the pole piece can be improved, and the reduction of the heat production during the battery test is facilitated.

Description

Technical Field

[0001] The utility model belongs to the technical field of battery production and manufacturing, and specifically relates to a winding core structure and a lithium ion battery. Background Art

[0002] As a new type of secondary battery, lithium-ion battery has the advantages of high energy density and power density, high operating voltage, light weight, small size, long cycle life, good safety, and environmental protection. It has broad application prospects in portable appliances, power tools, large energy storage, electric transportation power supply, etc. Lithium-ion batteries are widely used in 3C digital products due to their high energy density, good rate performance, and environmental protection. Low impedance, high rate, and high energy density batteries are becoming the mainstream in the consumer market, using thinner diaphragms and lower impedance designs, but they will have certain disadvantages in high temperature short circuit tests.

[0003] In the process of implementing the utility model, the inventors found that there are at least the following problems in the prior art. The high temperature external short circuit test is that the battery cell is connected to an internal resistor at 100% SOC to form a path as a whole. Due to the small internal resistance, the current passing through the path will be larger. According to the Joule's law formula, Q = I 2 Rt, the current generates heat through the tab, the green glue and diaphragm at the tab melt or shrink due to the heat, the empty aluminum foil at the slot short-circuit contacts the anode, resulting in increased heat generation, the SEI film and other substances cause decomposition and combustion, causing the test failure. Utility Model Content

[0004] One of the purposes of the utility model is to provide a winding core structure to address the deficiencies of the prior art. By optimizing the winding core structure, the internal resistance of the electrode short circuit can be increased, which helps to reduce the heat generation during battery testing.

[0005] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0006] A winding core structure comprises a first pole piece, a second pole piece and a diaphragm, wherein the first pole piece, the diaphragm and the second pole piece are stacked and wound in sequence to form a winding core; one of the first pole piece and the second pole piece has a welding slot, and the surface of the other of the first pole piece and the second pole piece is provided with an insulating layer and a first insulating glue in sequence; the insulating layer and the first insulating glue cover at least one side of the welding slot in the depth direction, the insulating layer is provided on the surface of the first pole piece or the second pole piece, and the first insulating glue is close to the welding slot.

[0007] Preferably, the length of the insulating layer is 10-40 mm, the width of the insulating layer is 8-30 mm, and the thickness of the insulating layer is 0.5-4 μm.

[0008] Preferably, the welding slot is welded with a pole ear, a second insulating glue is provided above and below the pole ear, the second insulating glue covers the welding slot, and the diaphragm is spaced between the first insulating glue and the second insulating glue.

[0009] Preferably, the first pole piece and the second pole piece both include a current collector and an active material layer, and the first pole piece and the second pole piece are both divided into a coating area and a hollow foil area, the current collector of the hollow foil area is exposed on the surface of the pole piece, and the current collector of the coating area is coated with the active material layer.

[0010] Preferably, two ends of the second insulating glue respectively contact the active material layer on both sides of the welding groove, and the insulating layer is coated on the surface of the active material layer.

[0011] Preferably, the welding groove is located in a coating area of ​​the first pole piece or the second pole piece, and the current collector of the welding groove is exposed on a surface of the first pole piece or the second pole piece.

[0012] Preferably, at least one side of one end of the first pole piece or one end of the second pole piece is a hollow foil area.

[0013] Preferably, the width of the insulating layer is equal to the width of the first insulating glue, and the width of the second insulating glue is smaller than the width of the first insulating glue.

[0014] Preferably, the insulating layer is a ceramic layer.

[0015] A second object of the present utility model is to provide a lithium-ion battery, comprising the above-mentioned winding core structure.

[0016] One of the above technical solutions has the following beneficial effects:

[0017] The utility model optimizes the winding core structure, sets a welding slot on the first pole piece, and coats an insulating layer at a position of the second pole piece corresponding to the welding slot, which helps to increase the internal resistance of the short circuit between the first pole piece and the second pole piece and reduce the heat generation during battery testing. At the same time, the insulating layer and the first insulating glue do not participate in the process of charging, discharging and de-inserting lithium, thereby ensuring the performance of the battery cell itself and avoiding affecting the long cycle performance of the battery cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The features, advantages and technical effects of exemplary embodiments of the present invention will be described below with reference to the accompanying drawings.

[0019] Figure 1 It is a structural schematic diagram of the first pole piece of the utility model.

[0020] Figure 2 It is a structural schematic diagram of the second pole piece of the utility model.

[0021] Figure 3 It is a structural schematic diagram of the winding core of the utility model.

[0022] Figure 4 for Figure 3 Enlarged view of point A.

[0023] The reference numerals are described as follows:

[0024] 1- first pole piece;

[0025] 2- second pole piece;

[0026] 3- diaphragm;

[0027] 4-Welding slot;

[0028] 5-Insulation layer;

[0029] 6-first insulating glue;

[0030] 7-Pole ear;

[0031] 8- second insulating glue;

[0032] 9-current collector;

[0033] 10-active material layer;

[0034] H - depth direction. DETAILED DESCRIPTION

[0035] For example, certain words are used in the specification and claims to refer to specific components. Those skilled in the art should understand that hardware manufacturers may use different terms to refer to the same component. This specification and claims do not use differences in names as a way to distinguish components, but use differences in the functions of components as the criteria for distinction. For example, "including" mentioned throughout the specification and claims is an open term, so it should be interpreted as "including but not limited to". "Approximately" means that within an acceptable error range, those skilled in the art can solve technical problems within a certain error range and basically achieve technical effects.

[0036] Furthermore, the terms “first”, “second”, etc. are used for descriptive purposes only and are not to be understood as indicating or implying relative importance.

[0037] In the utility model, unless otherwise clearly specified and limited, the terms "install", "connect", "connect", "fix" and the like 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 an indirect connection 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 utility model can be understood according to the specific circumstances.

[0038] The present invention will be further described in detail below in conjunction with the accompanying drawings, but the present invention is not limited thereto.

[0039] Implementation Method 1

[0040] During the high-temperature external short-circuit test, the current passes through the tab to generate heat, the green glue and diaphragm at the tab melt or shrink due to the heat, and the empty aluminum foil in the slot short-circuit contacts the anode, resulting in increased heat generation, and the SEI film and other substances decompose and burn, causing the test to fail.

[0041] The winding core structure of the utility model includes a first pole piece 1, a second pole piece 2 and a diaphragm 3, wherein the first pole piece 1, the diaphragm 3 and the second pole piece 2 are sequentially stacked and wound to form a winding core; one of the first pole piece 1 and the second pole piece 2 has a welding slot 4, and the surface of the other of the first pole piece 1 and the second pole piece 2 is sequentially provided with an insulating layer 5 and a first insulating glue 6; the insulating layer 5 and the first insulating glue 6 cover at least one side of the depth direction H of the welding slot 4, the insulating layer 5 is provided on the surface of the first pole piece 1 or the second pole piece 2, and the first insulating glue 6 is close to the welding slot 4. The utility model optimizes the winding core structure, provides a welding slot 4 on the first pole piece 1, and coats the insulating layer 5 at the position of the second pole piece corresponding to the welding slot 4, which helps to improve the internal resistance of the short circuit between the first pole piece 1 and the second pole piece 2, and reduce the heat generation during battery testing. At the same time, the insulating layer 5 and the first insulating glue 6 do not participate in the process of charging and discharging and lithium insertion and extraction, thereby ensuring the performance of the battery cell itself and avoiding affecting the long cycle performance of the battery cell.

[0042] It should be noted that: the depth direction of the welding slot 4 is the same as the thickness direction of the winding core, the welding slot 4 can be set for both the first pole piece 1 and the second pole piece 2, and the welding slot 4 is welded with a pole ear 7, and the first pole piece 1 and the second pole piece 2 can be provided with an insulating layer 5 and a first insulating glue 6 corresponding to the welding slot 4. In the winding state of the pole pieces, the first pole piece 1 and the second pole piece 2 are separated by the diaphragm 3, and it can also be understood that the first insulating glue 6 and the welding slot 4 are also separated by the diaphragm 3. There is no direct contact between the first insulating glue 6 and the welding slot 4. It can be understood that the first insulating glue 6 is located on the upper side or lower side of the welding slot 4, and it can also be understood as being located above or below the welding slot 4.

[0043] In the winding core structure according to the present invention, the length of the insulating layer 5 is 10 to 40 mm, the width of the insulating layer 5 is 8 to 30 mm, and the thickness of the insulating layer 5 is 0.5 to 4 μm. For example, the length of the insulating layer 5 is 10 mm, 20 mm, 30 mm, 40 mm, etc., the width of the insulating layer 5 is 8 mm, 10 mm, 12 mm, 14 mm, 16 mm, 18 mm, 20 mm, 22 mm, 24 mm, 26 mm, 28 mm, 30 mm, etc., and the thickness of the insulating layer 5 is 0.5 μm, 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, etc. The length and width of the insulating layer 5 are limited to ensure that the insulating layer 5 can completely cover the welding slot 4, which helps to increase the internal resistance of the short circuit between the pole pieces. At the same time, it prevents the insulating layer 5 from being too thick, which affects the overall thickness of the winding core.

[0044] In the winding core structure according to the utility model, the welding slot 4 is welded with a pole ear 7, and a second insulating glue 8 is arranged above and below the pole ear 7, and the second insulating glue 8 covers the welding slot 4. The diaphragm 3 is arranged between the first insulating glue 6 and the second insulating glue 8. Specifically, the pole ear 7 is embedded in the welding slot 4, and the thickness of the pole ear 7 is slightly smaller than the depth of the welding slot 4. The welding slot 4 can be arranged on both sides of the first pole piece 1 or the second pole piece 2, and the projections of the two welding slots 4 in the thickness direction of the pole piece overlap. The pole ear 7 is welded to the welding slot 4 on one side, and the second insulating glue 8 is arranged above and below the pole ear 7. The second insulating glue 8 covers the welding slot 4 on both sides of the pole piece. At the same time, the two ends of the second insulating glue 8 contact the active material layer 10 on both sides of the welding slot 4, which helps to improve the stability of the second insulating glue 8. Among them, the first insulating glue 6 and the second insulating glue 8 can be green glue in the art, or other insulating adhesive papers. The pole ear is an aluminum pole ear or a nickel pole ear, or other metal pole ears.

[0045] In the winding core structure according to the utility model, the first pole piece 1 and the second pole piece 2 both include a current collector 9 and an active material layer 10, and the first pole piece 1 and the second pole piece 2 are both divided into a coating area and a hollow foil area, the current collector 9 in the hollow foil area is exposed on the surface of the pole piece, and the current collector 9 in the coating area is coated with the active material layer 10. Specifically, the first pole piece 1 and the second pole piece 2 both include a current collector 9 and an active material layer 10 coated on the surface of the current collector 9, the surface of the pole piece has a hollow foil area, the thickness of the hollow foil area is less than the middle normal area, wherein the current collector 9 is exposed on the surface of the hollow foil area of ​​the pole piece, the hollow foil area is at both ends of the pole piece, and the active material covering area is outside the two ends of the current collector 9. The current collector 9 is a structure or part for collecting current. In lithium-ion batteries, it is mainly metal foil, such as copper foil, aluminum foil, composite current collector, etc., which mainly collects the current generated by the active material of the battery to form a larger current for external output. The current collector 9 needs to ensure full contact with the active material and ensure that the internal resistance is small.

[0046] In the winding core structure according to the utility model, the insulating layer 5 is a ceramic layer. The ceramic layer is used because the ceramic layer has stable performance and no side reaction occurs in the battery.

[0047] The working principle of the utility model is:

[0048] The utility model optimizes the winding core structure, sets a welding slot 4 on the first pole piece 1, and coats an insulating layer 5 at a position of the second pole piece corresponding to the welding slot 4, which helps to increase the internal resistance of the short circuit between the first pole piece 1 and the second pole piece 2 and reduce the heat generation during battery testing. At the same time, the insulating layer 5 and the first insulating glue 6 do not participate in the process of charging, discharging and de-inserting lithium, thereby ensuring the performance of the battery cell itself and avoiding affecting the long cycle performance of the battery cell.

[0049] Implementation Method 2

[0050] The difference from the first embodiment is that the insulating layer 5 of this embodiment is coated on the surface of the active material layer 10, the welding slot 4 is located in the coating area of ​​the first pole piece 1 or the second pole piece 2, and the current collector 9 of the welding slot 4 is exposed on the surface of the first pole piece 1 or the second pole piece 2. In this embodiment, the welding slot 4 can also be set in the coating area, which can be understood as the pole ear 7 being set in the middle of the pole piece. In addition, the pole ear 7 can also be set at the head and the middle of the pole piece respectively. The position and number of the pole ear 7 and the welding slot 4 are not limited here.

[0051] The other structures are the same as those in the first embodiment and will not be described in detail here.

[0052] Implementation Method 3

[0053] What is different from the first embodiment is that: in this embodiment, at least one side of one end of the first pole piece 1 or one end of the second pole piece 2 is a hollow foil area. In this embodiment, both sides of the tail end of the first pole piece 1 or the tail end of the second pole piece 2 are hollow foils. The width of the insulating layer 5 is equal to the width of the first insulating glue 6, ensuring that the insulating layer 5 can completely cover the welding slot 4, and the width of the second insulating glue 8 is smaller than the width of the first insulating glue 6, ensuring that the first insulating glue 6 can completely cover the second insulating glue 8.

[0054] The other structures are the same as those in the first embodiment and will not be described in detail here.

[0055] Lithium-ion battery

[0056] The utility model includes winding core structures of implementation modes 1 to 3.

[0057] The battery comprises a first pole piece 1, a separator 3 and a second pole piece 2, which are wound in sequence to form a bare battery cell, and at least one of the first pole piece 1 and the second pole piece 2 adopts the above structure.

[0058] The battery may include at least two stacked pole pieces with opposite polarities, the pole pieces with opposite polarities being the positive pole piece and the negative pole piece of the battery. In order to avoid short circuit between the positive and negative pole pieces, a diaphragm 3 is provided between each two adjacent pole pieces, and the pole pieces with opposite polarities are electrically isolated by the diaphragm 3.

[0059] In order to avoid short circuit between the positive and negative electrodes, the electrodes with opposite polarities are electrically isolated by the diaphragm 3. The first electrode 1 and the second electrode 2 have opposite polarities and are stacked on each other.

[0060] The first electrode sheet 1 may be a positive electrode sheet, and the second electrode sheet 2 may be a negative electrode sheet; or, the first electrode sheet 1 may be a negative electrode sheet, and the second electrode sheet 2 may be a positive electrode sheet, which is not limited here.

[0061] The battery containing the roll core structure of the utility model can also be used in electrical devices, and the electrical equipment can be automobiles, mobile phones, portable devices, laptops, ships, spacecraft, electric toys and electric tools, etc. Automobiles can be fuel vehicles, gas vehicles or new energy vehicles, and new energy vehicles can be pure electric vehicles, hybrid vehicles or extended-range vehicles, etc.; spacecraft include airplanes, rockets, space shuttles and spacecraft, etc.; electric toys include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys and electric airplane toys, etc.; electric tools include metal cutting electric tools, grinding electric tools, assembly electric tools and railway electric tools, such as electric drills, electric grinders, electric wrenches, electric screwdrivers, electric hammers, impact drills, concrete vibrators and electric planers, etc. The embodiments of the present application do not impose special restrictions on the above-mentioned electrical equipment.

[0062] According to the disclosure and teaching of the above description, the technicians in the field of the utility model can also change and modify the above implementation. Therefore, the utility model is not limited to the above specific implementation, and any obvious improvement, replacement or modification made by the technicians in this field on the basis of the utility model belongs to the protection scope of the utility model. In addition, although some specific terms are used in this specification, these terms are only for the convenience of explanation and do not constitute any limitation to the utility model.

Claims

1. A winding core structure, characterized in that: include: A first pole piece (1), a second pole piece (2) and a diaphragm (3), wherein the first pole piece (1), the diaphragm (3) and the second pole piece (2) are stacked in sequence and wound to form a winding core; One of the first pole piece (1) and the second pole piece (2) has a welding slot (4), and the surface of the other of the first pole piece (1) and the second pole piece (2) is provided with an insulating layer (5) and a first insulating glue (6) in sequence; the insulating layer (5) and the first insulating glue (6) cover at least one side of the welding slot (4) in a depth direction, the insulating layer (5) is provided on the surface of the first pole piece (1) or the second pole piece (2), and the first insulating glue (6) is close to the welding slot (4).

2. A winding core structure according to claim 1, characterized in that: The length of the insulating layer (5) is 10 to 40 mm, the width of the insulating layer (5) is 8 to 30 mm, and the thickness of the insulating layer (5) is 0.5 to 4 μm.

3. A winding core structure according to claim 1, characterized in that: The welding slot (4) is welded with a pole ear (7), and a second insulating glue (8) is arranged above and below the pole ear (7), the second insulating glue (8) covers the welding slot (4), and the diaphragm (3) is arranged between the first insulating glue (6) and the second insulating glue (8).

4. A winding core structure according to claim 3, characterized in that: The first pole piece (1) and the second pole piece (2) both comprise a current collector (9) and an active material layer (10); the first pole piece (1) and the second pole piece (2) are both divided into a coating area and a hollow foil area; the current collector (9) in the hollow foil area is exposed on the pole piece surface; and the current collector (9) in the coating area is coated with the active material layer (10).

5. A winding core structure according to claim 4, characterized in that: The two ends of the second insulating glue (8) respectively contact the active material layer (10) on both sides of the welding slot (4), and the insulating layer (5) is coated on the surface of the active material layer (10).

6. A winding core structure according to claim 5, characterized in that: The welding slot (4) is located in the coating area of ​​the first pole piece (1) or the second pole piece (2), and the current collector (9) of the welding slot (4) is exposed on the surface of the first pole piece (1) or the second pole piece (2).

7. A winding core structure according to claim 5, characterized in that: At least one side of one end of the first pole piece (1) or one end of the second pole piece (2) is a hollow foil area.

8. A winding core structure according to claim 3, characterized in that: The width of the insulating layer (5) is equal to the width of the first insulating glue (6), and the width of the second insulating glue (8) is smaller than the width of the first insulating glue (6).

9. A winding core structure according to any one of claims 1 to 8, characterized in that: The insulating layer (5) is a ceramic layer.

10. A lithium ion battery, characterized in that: The invention comprises the winding core structure as described in any one of claims 1 to 9.

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