Battery cell and battery

Abstract

The application discloses a secondary battery cell and a battery. The secondary battery cell comprises a winding core, a first pole piece, a diaphragm and a second pole piece which are arranged in a layering winding mode, the second pole piece is opposite to the first pole piece in polarity, and the top end of the second pole piece exceeds the top end of the first pole piece to form a step; and a gum paper which is adhered to the winding core along the winding direction of the winding core and covers the step. The application adheres the gum paper to the winding core, so that a buffer zone composed of the gum paper is formed between the winding core and the shell, direct contact between the edge of the winding core and the shell is prevented, the shell is prevented from being abraded, and the service life of the battery is prolonged.

Description

Technical Field

[0001] This application relates to the field of secondary battery technology, and in particular to a secondary battery cell and a secondary battery. Background Technology

[0002] Secondary batteries (such as lithium-ion batteries) are a key component of electrochemical energy storage systems. They contain lithium (specifically in the form of metallic lithium, lithium alloys, lithium ions, and lithium polymers) and have wide applications in many fields, including consumer electronics.

[0003] In lithium battery manufacturing technology, the mainstream lithium battery types on the market are mainly divided into two types: stacked and wound. Wound batteries are made by stacking positive and negative electrode sheets and separators in sequence and then winding them. This manufacturing method has excellent production efficiency and also helps to better control production costs, thus having certain advantages in industrial production.

[0004] However, the structural characteristics of wound batteries lead to drawbacks in practical applications. In the design of secondary battery cells, the negative electrode needs to be in excess of the positive electrode to ensure normal and safe operation. This creates a stepped structure in the overhang area between the positive and negative electrodes, with the edge of this step being the edge of the positive electrode. Later in the battery cycle, as the charging and discharging process progresses, the cell undergoes periodic expansion and contraction. With repeated expansion and contraction, the aforementioned step shifts, causing continuous friction between the step and the battery casing. This continuous friction can lead to cracks or damage to the battery casing, severely impacting the battery's lifespan. Utility Model Content

[0005] The main purpose of this application is to propose a cell and battery for a secondary battery, which aims to solve the problem of damage to the battery casing caused by friction between the cell and the battery casing in existing wound secondary batteries.

[0006] To achieve the above objectives, this application proposes a cell for a secondary battery, comprising:

[0007] The core includes a first electrode, a diaphragm, and a second electrode arranged in a stacked and wound manner. The second electrode has the opposite polarity to the first electrode, and the top of the second electrode extends beyond the top of the first electrode to form a step.

[0008] Adhesive tape is bonded to the core along the winding direction and covers the steps.

[0009] In some embodiments, the width of the adhesive tape bonded to the outermost first electrode is L1, satisfying: 6mm≤L1≤10mm.

[0010] In some embodiments, the distance between the top of the first electrode and the top of the second electrode is X1, the distance between the top of the second electrode and the top of the diaphragm is X2, and the upper edge of the adhesive tape extends beyond the top of the first electrode by a distance L2, satisfying: L2≥X1+X2.

[0011] In some embodiments, the device further includes a first electrode tab and a second electrode tab, the first electrode tab being connected to a first electrode plate and the second electrode tab being connected to a second electrode plate, and a wrapping adhesive being provided between the first electrode tab and the second electrode tab, with both ends of the wrapping adhesive being attached to the core.

[0012] In some embodiments, the adhesive tape includes a first adhesive tape and a second adhesive tape, which are located on opposite sides of the adhesive wrapping.

[0013] In some embodiments, the length of the second tape is the same as the length of the first tape.

[0014] In some embodiments, the thickness of the adhesive tape is T1, and the thickness of the adhesive wrapping is T, satisfying: 12um≤T1≤T.

[0015] In some embodiments, the adhesive tape is a polyimide-based tape.

[0016] In another aspect, this application proposes a battery comprising a casing and the aforementioned secondary battery cell, wherein the secondary battery cell is disposed within the casing.

[0017] In some embodiments, the adhesive tape is bonded to the inner wall of the housing.

[0018] This application proposes a secondary battery cell and battery. The secondary battery cell includes a core and adhesive tape. By attaching adhesive tape to the core, a buffer zone made of adhesive tape is formed between the core and the casing, preventing the edge of the core from directly contacting the casing, avoiding wear on the casing, and thus improving the battery's service life. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the battery cell structure in one embodiment of this application;

[0020] Figure 2 This is a schematic diagram of the cross-sectional structure of the core in one embodiment of this application;

[0021] Figure 3 This is a schematic diagram of the structure of the battery cell being bonded to the winding core in one embodiment of this application.

[0022] Explanation of icon numbers:

[0023] Core 100; First electrode 110; Diaphragm 120; Second electrode 130; First electrode tab 140; Second electrode tab 150; Glue wrap 160; Adhesive paper 200; First adhesive tape 210; Second adhesive tape 220. Detailed Implementation

[0024] The solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments in this application, and not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0025] It should be noted that all directional indicators (such as up, down, left, right, front, back, etc.) in the embodiments of this application are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicator will also change accordingly.

[0026] It should also be noted that when a component is described as "fixed to" or "set on" another component, it can be directly on the other component or there may be an intervening component present. When a component is described as "connected to" another component, it can be directly connected to the other component or there may be an intervening component present.

[0027] Furthermore, the use of terms such as "first" and "second" in this application is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. Additionally, the technical solutions of the various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. When the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed in this application.

[0028] This application provides an embodiment of a secondary battery cell, referring to... Figure 1 , Figure 1 This is a schematic diagram of the cell structure in one embodiment of this application. The cell of the secondary battery includes:

[0029] The core 100 includes a first electrode 110, a diaphragm 120 and a second electrode 130 that are stacked and wound together. The second electrode 130 has the opposite polarity to the first electrode 110, and the top of the second electrode 130 extends beyond the top of the first electrode 110 to form a step.

[0030] Adhesive tape 200 is bonded to the core 100 along the winding direction of the core 100 and covers the step.

[0031] Reference Figure 2 , Figure 2This is a schematic cross-sectional view of the core 100 in one embodiment of this application. The core 100 is formed by winding a first electrode 110, a diaphragm 120, and a second electrode 130 in a specific order. In this embodiment, the first electrode 110 is a positive electrode, and the second electrode 130 is a negative electrode. At the top of the core 100, the top of the second electrode 130 extends beyond the top of the first electrode 110, meaning the second electrode 130 is higher than the first electrode 110. Therefore, a step is formed on the outermost side of the core 100, and the edge of this step is the edge of the first electrode 110. In this embodiment, adhesive tape 200 is provided on the core 100 along the winding direction. The adhesive tape 200 is adhered to one end of the core 100 and covers the step. By setting adhesive tape 200 on the core 100, a buffer zone made of adhesive tape 200 is formed between the aforementioned step and the battery casing, preventing direct contact between the step and the casing, avoiding wear on the casing by the step, and thus improving the battery's service life.

[0032] In a preferred embodiment, the width L1 of the adhesive tape 200 bonded to the outermost first electrode 110 satisfies: 6mm ≤ L1 ≤ 10mm. In this embodiment, the value of L1 can be set within the range of 6mm to 10mm. For example, in actual production, the width L1 of the adhesive tape 200 bonded to the first electrode 110 can be set to different values ​​such as 6mm, 8mm, and 10mm according to different design requirements. Specifically, setting the width L1 of the adhesive tape 200 bonded to the first electrode 110 to 10mm ensures that the adhesive tape 200 can increase the adhesion area to generate sufficient strength; setting the width L1 of the adhesive tape 200 bonded to the first electrode 110 to 8mm can reduce some production costs while ensuring stable adhesion; setting the width L1 of the adhesive tape 200 bonded to the first electrode 110 to 6mm can reduce the amount of adhesive tape 200 used and lower production costs, but the strength is relatively low. In this embodiment, since the width L1 of the adhesive tape 200 bonded to the first electrode 110 is limited to between 6mm and 10mm, the adhesive tape 200 can be firmly adhered to the first electrode 110, thereby effectively preventing the adhesive tape 200 from falling off during subsequent use or transportation.

[0033] In this embodiment, the height of the adhesive tape 200 can be selected in several ways. Generally, the top of the adhesive tape 200 can be set to extend beyond the top of the first electrode 110. In a preferred embodiment, along the length direction of the core 100, the distance between the top of the first electrode 110 and the top of the second electrode 130 is defined as X1, the distance between the top of the second electrode 130 and the top of the diaphragm 120 is defined as X2, and the distance by which the upper edge of the adhesive tape 200 extends beyond the top of the first electrode 110 is defined as L2, satisfying: L2≥X1+X2. In a preferred embodiment, the distance L2 by which the upper edge of the adhesive tape 200 extends beyond the top of the first electrode 110 is set to be equal to the sum of X1 and X2. However, in actual use, the value range of the distance L2 by which the upper edge of the adhesive tape 200 extends beyond the top of the first electrode 110 can have a processing error of 0.2mm to facilitate the production of the adhesive tape 200. This embodiment limits the distance between the upper edge of the adhesive tape 200 and the top of the first electrode 110 to achieve a stable adhesion between the adhesive tape 200 and the core 100, preventing the adhesive tape 200 from falling off during use due to flipping, ensuring that the adhesive tape 200 can cover the step, avoiding direct contact between the step and the housing, thereby preventing wear on the housing.

[0034] In a preferred embodiment of this application, reference is made to... Figure 1 and Figure 3 , Figure 1 This is a schematic diagram of the battery cell structure in one embodiment of this application. Figure 3 This is a schematic diagram of the structure of the battery cell being bonded to the winding core in one embodiment of this application. It also includes a first tab 140 and a second tab 150. The first tab 140 is connected to the first electrode 110, and the second tab 150 is connected to the second electrode 130. A wrapping adhesive 160 is provided between the first tab 140 and the second tab 150, and the two ends of the wrapping adhesive 160 are attached to the winding core 100.

[0035] In this embodiment, the first tab 140 can be welded to the first electrode 110, and the second tab 150 can be welded to the second electrode 130. Furthermore, an adhesive wrap 160 is provided between the first tab 140 and the second tab 150. The two ends of this adhesive wrap 160 are respectively attached to both sides of the core 100. Its main function is to fix the winding structure of the core 100, preventing the core 100 from loosening or deforming during subsequent use or transportation, thereby ensuring the stability and reliability of the battery structure. Since the outermost part of the core 100 winding is the first electrode 110, the two ends of the adhesive wrap 160 are attached to the first electrode 110. To achieve the best adhesion effect, the distance between the end of the adhesive wrap 160 and the top of the first electrode 110 can be controlled within the range of 6mm to 10mm. For example, in actual production, the distance can be set to different values ​​such as 6mm, 8mm, 10mm, etc., according to different needs. That is, the end of the adhesive wrap 160 is flush with the lower edge of the adhesive paper 200 to ensure that the adhesion strength is achieved while maintaining visual consistency.

[0036] In this embodiment, the adhesive tape 200 can completely cover the first electrode sheet or partially cover it. In a preferred embodiment, such as... Figure 3 As shown, Figure 3 This is a schematic diagram of the structure of the battery cell being bonded to the core in one embodiment of this application. The adhesive tape includes a first adhesive tape and a second adhesive tape, which are located on both sides of the adhesive wrapping. In this embodiment, along the width direction of the core 100, the circumference of the core 100 is X3, the width of the adhesive wrapping 160 is X4, the length of the first adhesive tape 210 is L3, and the length of the second adhesive tape 220 is the same as the length of the first adhesive tape 210, satisfying: L3 = (X3 - 2X4) / 2.

[0037] The adhesive tape 200 consists of two parts: a first adhesive tape 210 and a second adhesive tape 220. Looking at the width of the core 100, the first adhesive tape 210 and the second adhesive tape 220 are located on opposite sides of the wrapping tape 160. The first adhesive tape 210 is attached to the core 100 on the left side of the wrapping tape 160, and the second adhesive tape 220 is attached to the core 100 on the right side of the wrapping tape 160. In this direction, the circumference of the core 100 is denoted as X3, the width of the wrapping tape 160 is denoted as X4, and the lengths of the first adhesive tape 210 and the second adhesive tape 220 are equal. The length of the first adhesive tape 210 is denoted as L3. To ensure that the first adhesive tape 210 and the second adhesive tape 220 completely cover the outer side of the core 100 and wrap around the edge of the first electrode sheet 110, the length L3 of the first adhesive tape 210 needs to be limited.

[0038] Specifically, since the cores 100 on both sides of the wrapping adhesive 160 are of equal length, the length of the core 100 on the left (or right) side of the wrapping adhesive 160 can be obtained by subtracting the widths X4 of the upper and lower wrapping adhesive 160 from the perimeter X3 of the core 100, and then dividing the difference by 2. This length is the length L3 of the first tape 210 or the second tape 220, i.e., L3 = (X3 - 2X4) / 2. This design allows the first tape 210 and the second tape 220 to be respectively attached to the cores 100 on the left and right sides of the wrapping adhesive 160, ensuring that the edges of the cores 100 are completely covered by the first tape 210, the second tape 220, and the wrapping adhesive 160. This effectively prevents direct contact between the step and the casing, thus preventing casing wear and improving battery safety and stability.

[0039] In a preferred embodiment, refer to Figure 2 and Figure 3 , Figure 2 This is a schematic diagram of the cross-sectional structure of the core 100 in one embodiment of this application. Figure 3 This is a schematic diagram of the structure of the battery cell being bonded to the core with adhesive in one embodiment of this application. The thickness of the adhesive paper 200 is T1, and the thickness of the adhesive wrapping 160 is T, satisfying: 12um≤T1≤T.

[0040] In this embodiment, observed along the width of the core 100, the adhesive tape 200 and the wrapping tape 160 each have a certain thickness. The thickness of the adhesive tape 200 is denoted as T1, and the thickness of the wrapping tape 160 is denoted as T. To ensure the overall thickness is not affected, the thickness T1 of the adhesive tape 200 is limited, requiring it to be within the range of 12µm to the thickness T of the wrapping tape 160, i.e., 12µm ≤ T1 ≤ T. This setting ensures that the thickness of the adhesive tape 200 will not exceed the thickness of the wrapping tape 160, thus avoiding any additional impact on the overall thickness. Here, if the thickness of the adhesive tape 200 is less than 12µm, its protective effect is insufficient and it cannot resist the continuous friction of the step. Therefore, the thickness of the adhesive tape 200 must be at least greater than 12µm to protect the shell from wear.

[0041] In a preferred embodiment, the adhesive tape 200 is a polyimide-based tape.

[0042] In this embodiment, the adhesive tape 200 used is a polyimide-based tape, which has excellent electrolyte resistance and can resist electrolyte corrosion, while also providing strong protection. In contrast, if PET adhesive tape 200 is used, due to its relatively poor elongation, it is prone to detachment during battery cycling as the core 100 gradually thickens, thus affecting its protective effect. PP adhesive tape 200 has a larger swelling rate and is also prone to detaching from its original position during battery cycling, leading to a decrease in protective performance. Therefore, polyimide-based tape is chosen as the preferred embodiment.

[0043] This application further proposes a battery comprising a casing and a secondary battery cell, wherein the secondary battery cell is disposed inside the casing. The specific structure of the secondary battery cell is as described in the above embodiments. Since this battery employs all the technical solutions of all the above embodiments, it possesses at least all the technical effects brought about by the technical solutions of the above embodiments, and will not be elaborated upon further here.

[0044] In some embodiments, the adhesive tape 200 is bonded to the inner wall of the housing, which is an aluminum-plastic film. The adhesive tape 200 is bonded to both the core 100 and the inner wall of the housing, which can prevent the step from rubbing against the housing while positioning the core 100 inside the housing, preventing the core 100 from shifting, and further improving battery safety.

[0045] Please refer to the following test table for detailed test results:

[0046]

[0047] In the test environment of this test table, the perimeter X3 of the core 100 is 130mm, the width X4 of the wrapping tape 160 is 6mm, the length L3 of the first tape 210 is 59mm, the length of the second tape is equal to that of the first tape, and the test is conducted after the core 100 has completed 800 full charge-discharge cycles at room temperature.

[0048] Comparing Examples 1, 2, 3 and 5, it can be seen that, under the condition that other conditions remain unchanged, setting the width L1 of the adhesive tape 200 bonded to the first electrode 110 between 6mm and 10mm can ensure the protective effect of the adhesive tape 200. If the width L1 of the adhesive tape 200 bonded to the first electrode 110 is lower than this range, as in Example 5, the adhesive tape 200 is prone to shifting and falling off, resulting in slight wear in some areas of the aluminum-plastic film.

[0049] Comparing Examples 1 and 4, it can be seen that the sum of the distance X1 between the top of the first electrode 110 and the top of the second electrode 130 and the distance X2 between the top of the second electrode 130 and the top of the diaphragm 120 is 5mm. Therefore, setting the distance L2 of the upper edge of the adhesive tape 200 beyond the top of the first electrode 110 to 5mm can ensure the protective effect of the adhesive tape 200. However, as shown in Example 4, setting L2 to 8mm can also achieve a protective effect. Therefore, the value of L2 should satisfy L2≥X1+X2. It should be noted that, comparing Examples 1 and 6, it can be seen that if the distance L2 of the upper edge of the adhesive tape 200 beyond the top of the first electrode 110 is less than the sum of the distance X1 between the top of the first electrode 110 and the top of the second electrode 130 and the distance X2 between the top of the second electrode 130 and the top of the diaphragm 120, the adhesive tape 200 will not be able to completely cover the step. During use, the adhesive tape is prone to flipping, leading to wear of the aluminum-plastic film.

[0050] Comparing Examples 1 and 7, it can be seen that when the thickness T1 of the adhesive tape 200 is 12µm, the adhesive tape 200 can play a protective role. When the thickness T1 of the adhesive tape 200 is less than 12µm, as shown in Example 7, the thickness of the adhesive tape 200 is too low and it is easily worn through by the step, which in turn causes slight wear on the aluminum-plastic film.

[0051] Comparing Examples 1, 8, and 9, it can be seen that, under the condition that other conditions remain unchanged, the protective effect of polyimide is stronger than that of polyethylene terephthalate and polypropylene. Therefore, the material of the adhesive tape 200 is preferably polyimide.

[0052] In summary, this application proposes a secondary battery cell and battery. The secondary battery cell includes a core 100 and adhesive tape 200. By attaching adhesive tape 200 to the core 100, a buffer zone composed of adhesive tape 200 is formed between the core 100 and the casing. The length, thickness and other dimensional parameters of the adhesive tape 200 are optimized to prevent the edge of the core 100 from directly contacting the casing, avoiding wear on the casing and thus improving the battery's service life.

[0053] The above description is only a part or preferred embodiment of this application. Neither the text nor the drawings should limit the scope of protection of this application. All equivalent structural transformations made using the content of this application's specification and drawings under the overall concept of this application, or direct / indirect applications in other related technical fields, are included within the scope of protection of this application.

Claims

1. A cell for a secondary battery, characterized in that, include: The core includes a first electrode, a diaphragm, and a second electrode that are stacked and wound together. The second electrode has the opposite polarity to the first electrode, and the top of the second electrode extends beyond the top of the first electrode to form a step. Adhesive tape is bonded to the core along the winding direction of the core and covers the step.

2. The cell of the secondary battery according to claim 1, characterized in that, The width of the adhesive tape bonded to the outermost ring of the first electrode is L1, which satisfies: 6mm≤L1≤10mm.

3. The cell of the secondary battery according to claim 2, characterized in that, The distance between the top of the first electrode and the top of the second electrode is X1, the distance between the top of the second electrode and the top of the diaphragm is X2, and the upper edge of the adhesive paper extends beyond the top of the first electrode by a distance L2, satisfying: L2≥X1+X2.

4. The cell of the secondary battery according to claim 2, characterized in that, It also includes a first electrode tab and a second electrode tab, the first electrode tab being connected to the first electrode plate, the second electrode tab being connected to the second electrode plate, and a wrapping adhesive being provided between the first electrode tab and the second electrode tab, with both ends of the wrapping adhesive being attached to the core.

5. The cell of the secondary battery according to claim 4, characterized in that, The adhesive tape includes a first adhesive tape and a second adhesive tape, which are located on both sides of the adhesive wrapping.

6. The cell of the secondary battery according to claim 5, characterized in that, The length of the second tape is the same as the length of the first tape.

7. The cell of the secondary battery according to claim 6, characterized in that, The thickness of the adhesive tape is T1, and the thickness of the wrapping adhesive is T, satisfying: 12um≤T1≤T.

8. The cell of the secondary battery according to claim 1, characterized in that, The adhesive tape is a polyimide-based tape.

9. A battery, characterized in that, It includes a housing and a cell of a secondary battery as described in any one of claims 1 to 8, wherein the cell of the secondary battery is disposed within the housing.

10. The battery according to claim 9, characterized in that, The adhesive tape is bonded to the inner wall of the housing.

Images