Diaphragm, battery and electric device

Abstract

The utility model belongs to the technical field of battery structures, and particularly relates to a diaphragm, which comprises a base membrane and a coating coated on the base membrane, bulges are respectively arranged at two ends of the diaphragm, an accommodating space is formed between the two bulges, and the accommodating space is used for placing a pole piece. According to the utility model, the bulges are arranged to form the accommodating space, and the accommodating space is used for positioning the pole pieces, so that the condition of dislocation of the pole pieces is prevented, the possibility of short circuit of the battery cell is reduced, and the safety performance of the battery cell is further improved. In addition, the utility model also discloses a battery comprising the diaphragm and an electric device.

Description

Technical Field

[0001] The utility model belongs to the technical field of battery structure, and specifically relates to a diaphragm, a battery and an electrical device. Background Art

[0002] Nowadays, with the development of modern society and the enhancement of people's environmental awareness, more and more devices choose lithium-ion batteries as power sources, such as mobile phones, laptops, power tools and electric vehicles, which provides a broad space for the application and development of lithium-ion batteries.

[0003] At present, in order to pursue higher energy density, lithium-ion batteries further reduce the width between the diaphragm and the anode, the anode and the cathode, and the cathode and the diaphragm when designing the battery cell. Although reducing the width can achieve the purpose of improving the energy density of the battery cell, it causes the pole pieces to be easily misaligned during the production process of the battery cell, increasing the possibility of short circuit of the battery cell. Therefore, it is urgent to propose a new technical solution to solve the above problems. Utility Model Content

[0004] One of the purposes of the utility model is to provide a diaphragm to address the deficiencies of the prior art, which can position the pole piece by providing a protrusion to prevent the pole piece from being misplaced and causing a short circuit.

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

[0006] A diaphragm comprises a base film and a coating coated on the base film. Both ends of the diaphragm are respectively provided with protrusions, and an accommodation space is formed between the two protrusions. The accommodation space is used to place a pole piece.

[0007] In the utility model, the accommodating space can position the pole piece due to the setting of the protrusion, thereby preventing the pole piece from being misplaced during the battery cell manufacturing process, and further preventing the battery cell from being short-circuited due to the misplacement of the pole piece, thereby reducing the difficulty of battery cell manufacturing and improving the safety performance of the battery cell.

[0008] As an improvement of the diaphragm described in the utility model, the height of the protrusion is H1, the thickness of the pole piece is H2, and the H1 and H2 satisfy the relationship: H1-0.5μm≤H2≤H1+0.5μm. While ensuring that the protrusion can fix the pole piece, it prevents the height of the protrusion from being too high, resulting in a gap between the pole piece and the base membrane, and occupying too much space in the battery cell, thereby preventing it from affecting the energy density of the battery cell.

[0009] As an improvement of the diaphragm described in the utility model, in the length direction of the diaphragm, the length direction and the width direction W are equivalent to the X-axis direction and the Y-axis direction in the coordinate system and are perpendicular to each other, and the interval between two adjacent protrusions is L, and the L and the H2 satisfy the relationship: 1 / 3×H2≤L≤1 / 2×H2. A gap is set between the two protrusions in the length direction. In practical applications, after the diaphragm is hot-pressed, the part of the protrusion thickness that exceeds the corresponding pole piece thickness can extend toward both sides to fill the above gap, further preventing the existence of the protrusion from causing the volume energy density of the battery cell to decrease.

[0010] As an improvement of the diaphragm described in the utility model, the width of the accommodating space in the width direction of the diaphragm is set to 5mm-80mm.

[0011] As an improvement of the diaphragm described in the utility model, the height of the protrusion is set to 40μm-100μm; the setting of the protrusion height and the width of the accommodating space ensures the width between the electrode and the diaphragm and between the electrode and the electrode in the formed battery cell, reducing the risk of short circuit.

[0012] As an improvement of the diaphragm described in the utility model, the protrusion is formed by the base film, and the protrusion passes through the coating and is exposed on the coating.

[0013] As an improvement of the diaphragm described in the utility model, the protrusion is formed by the base film, and the coating is coated on the protrusion.

[0014] As an improvement of the diaphragm described in the utility model, the protrusion is formed by the coating, and the protrusion and the coating are formed in one piece.

[0015] As an improvement of the diaphragm described in the utility model, the protrusion is configured as one of a point-shaped structure, a drop-shaped structure, a linear structure and a polygonal structure.

[0016] The second object of the present utility model is to provide a battery, comprising the above-mentioned diaphragm and a pole piece stacked or wound with the diaphragm.

[0017] The third purpose of the utility model is to provide an electrical device including the battery as described above.

[0018] The beneficial effect of the utility model is that the diaphragm of the utility model comprises a base film and a coating coated on the base film, and protrusions are respectively arranged at both ends of the diaphragm, and a housing space is formed between the two protrusions, and the housing space is used to place the pole piece. The utility model forms a housing space by arranging protrusions on the diaphragm, and the housing space forms a groove structure due to the arrangement of the protrusions, which can locate the position of the pole piece, avoid the pole piece from shifting during the production process of the battery cell, ensure the width distance between the diaphragm and the pole piece and between the pole pieces, and thus reduce the risk of short circuit of the battery cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The features, advantages and technical effects of exemplary embodiments of the present invention will be described below with reference to the accompanying drawings.

[0020] Figure 1 This is one of the cross-sectional schematic diagrams of the diaphragm of the present utility model.

[0021] Figure 2 This is the second cross-sectional schematic diagram of the diaphragm of the utility model.

[0022] Figure 3 This is the third cross-sectional schematic diagram of the diaphragm of the present utility model.

[0023] Figure 4 This is the fourth cross-sectional schematic diagram of the diaphragm of the present utility model.

[0024] Figure 5 This is a diagram showing the positional relationship between the diaphragm and the pole piece in the utility model.

[0025] The reference numerals are described as follows:

[0026] 1-basement membrane;

[0027] 2- coating;

[0028] 3- convex;

[0029] 100-diaphragm; 200-pole piece.

[0030] W-width direction; C-length direction. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0032] Unless otherwise defined, all technical and scientific terms used in this application have the same meanings as those commonly understood by technicians in the technical field to which this application belongs; the terms used in the specification of this application are only for the purpose of describing specific implementation methods and are not intended to limit this application; the terms "including" and "having" in the specification and claims of this application and the above-mentioned figure descriptions and any variations thereof are intended to cover non-exclusive inclusions.

[0033] Reference to "embodiment" in this application means that a particular feature, structure or characteristic described in conjunction with the embodiment may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments.

[0034] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", and "attached" 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 direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0035] In the embodiments of the present application, the same reference numerals represent the same components, and for the sake of brevity, detailed descriptions of the same components are omitted in different embodiments. It should be understood that the thickness, length, width and other dimensions of various components in the embodiments of the present application shown in the drawings, as well as the overall thickness, length, width and other dimensions of the integrated device are only exemplary descriptions and should not constitute any limitation to the present application.

[0036] In the present application, battery cells may include lithium-ion secondary batteries, lithium-ion primary batteries, lithium-sulfur batteries, sodium-lithium-ion batteries, sodium-ion batteries or magnesium-ion batteries, etc., and the embodiments of the present application do not limit this. Battery cells may be cylindrical, flat, rectangular or other shapes, etc., and the embodiments of the present application do not limit this. Battery cells are generally divided into three types according to the packaging method: cylindrical battery cells, square battery cells and soft-pack battery cells, and the embodiments of the present application do not limit this.

[0037] The battery cell includes a battery core and an electrolyte. The battery core is composed of a positive electrode sheet, a negative electrode sheet and a separator. The battery cell mainly relies on the movement of metal ions between the positive electrode sheet and the negative electrode sheet to work. The positive electrode sheet includes a positive electrode collector and a positive electrode active material layer. The positive electrode active material layer is coated on the surface of the positive electrode collector. The positive electrode collector not coated with the positive electrode active material layer protrudes from the positive electrode collector coated with the positive electrode active material layer. The positive electrode collector not coated with the positive electrode active material layer serves as the positive electrode tab. Taking lithium-ion batteries as an example, the material of the positive electrode collector can be aluminum, and the positive electrode active material can be lithium cobalt oxide, lithium iron phosphate, ternary lithium or lithium manganese oxide. The negative electrode sheet includes a negative electrode collector and a negative electrode active material layer. The negative electrode active material layer is coated on the surface of the negative electrode collector. The negative electrode collector not coated with the negative electrode active material layer protrudes from the negative electrode collector coated with the negative electrode active material layer. The negative electrode collector not coated with the negative electrode active material layer serves as the negative electrode tab. The material of the negative electrode current collector may be copper, and the negative electrode active material may be carbon or silicon, etc. In order to ensure that a large current can pass without melting, the number of positive electrode tabs is multiple and stacked together, and the number of negative electrode tabs is multiple and stacked together. The material of the isolation film may be PP (polypropylene) or PE (polyethylene), etc. In addition, the battery cell may be a wound structure or a laminated structure, and the embodiments of the present application are not limited thereto.

[0038] The development of battery technology must take into account many design factors at the same time, such as energy density, cycle life, discharge capacity, charge and discharge rate and other performance parameters. In addition, battery safety must also be considered.

[0039] The inventors found that energy density is an important parameter for measuring battery performance. In the existing battery structure, in order to improve the energy density of the battery, the distance between the pole pieces and between the pole pieces and the diaphragm is reduced. Although the effect of improving the energy density can be achieved, the possibility of battery short circuit due to pole piece misalignment is also increased. In view of this, the embodiment of the present application provides a technical solution, which provides a protrusion on the diaphragm to locate the pole piece position, so that even if the width between the pole piece and the diaphragm is reduced, the pole piece misalignment and short circuit will not occur.

[0040] The following is combined with Figures 1 to 5 The utility model is further described in detail with specific implementation modes, but is not intended to limit the utility model.

[0041] like Figure 1As shown, a diaphragm includes a base film 1 and a coating 2 coated on the base film 1, and protrusions 3 are respectively provided at both ends of the diaphragm, and a receiving space is formed between the two protrusions 3, and the receiving space is used to place the pole piece. Due to the setting of the protrusions 3, the receiving space forms a groove structure, which can position the corresponding pole piece, and when the width distance between the pole pieces and the pole pieces and the diaphragm is reduced, the pole pieces can be prevented from being misaligned during the production process of the battery cell, thereby reducing the risk of short circuit of the battery cell and improving the safety performance of the battery cell.

[0042] Preferably, the width of the accommodating space in the width direction W of the diaphragm is set to 5 mm-80 mm, matching the width of the corresponding electrode piece, thereby ensuring the flatness of the battery cell during the subsequent manufacturing process.

[0043] It should be noted that Figure 4 and Figure 5 The structure of the diaphragm is Figure 1 , Figure 2 and Figure 3 Any of the above, in order to clearly mark the parameters and to show its specific structure,

[0044] Preferably, Figure 5 As shown, the height of the protrusion 3 is set to 40μm-100μm, the height of the protrusion 3 is H1, the thickness of the pole piece is H2, H1 and H2 satisfy the relationship: H1-0.5μm≤H2≤H1+0.5μm, while ensuring that the protrusion 3 can fix the pole piece, it prevents the height of the protrusion 3 from being too high, resulting in a gap between the pole piece and the base film 1, and occupying too much space in the battery cell, thereby preventing it from affecting the energy density of the battery cell.

[0045] Preferably, Figure 4 As shown, in the length direction C of the diaphragm, the length direction C and the width direction W are equivalent to the X-axis direction and the Y-axis direction in the coordinate system and are perpendicular to each other. The interval between two adjacent protrusions 3 is L, and L and H2 satisfy the relationship: 1 / 3×H2≤L≤1 / 2×H2. A gap is set between the two protrusions 3 in the length direction C. In practical applications, after the diaphragm is hot-pressed, the part of the protrusion 3 thickness that exceeds the thickness of the corresponding pole piece can extend toward both sides to fill the above gap, so that the height of the protrusion 3 is flush with the thickness of the corresponding pole piece, further preventing the existence of the protrusion 3 from causing the volume energy density of the battery cell to decrease; at the same time, the setting of the gap can also provide a path for the electrolyte to enter the battery cell, ensure the infiltration of the battery cell, and then ensure the electrical performance of the battery.

[0046] Preferably, the protrusion 3 is set to a point-shaped structure, and can also be set to a teardrop-shaped structure, a linear structure, a polygonal structure or one of other shapes, which can be adjusted according to actual conditions and needs without specific settings.

[0047] Preferably, the protrusion 3 is formed by the base film 1, and the protrusion 3 passes through the coating 2 and is exposed on the coating 2. In the actual production process, the raw material of the base film 1 is molded by a gravure roller and then stretched to obtain the base film 1 with the protrusion 3, and then the coating material is coated.

[0048] In some other embodiments, Figure 2 As shown, the protrusion 3 is formed by the base film 1, and the coating 2 is coated on the protrusion 3, which can further improve the isolation performance of the diaphragm.

[0049] In some other embodiments, Figure 3 As shown, the protrusion 3 is formed by the coating 2, and the protrusion 3 and the coating 2 are integrally formed. In the actual production process, the coating 2 is coated with a gravure roller of a fixed size and shape to obtain the coating 2 with the protrusion 3. The production method is simple.

[0050] In order to better illustrate the beneficial effects of the present embodiment, the following examples and comparative examples are set for experimental description, wherein the diaphragm in Examples 1-5 is a diaphragm structure with a protrusion 3 in the present embodiment, the comparative example is a conventional diaphragm structure, and other structures are the same. Examples 1-5 and the comparative example are applied to the conventional model 642932, and the average thickness of the bare cell is 5.55±0.15 mm. Conventional X-ray, short circuit, and bare cell thickness tests are performed. The diaphragm parameter settings are shown in Table 1, and the test results are shown in Table 2.

[0051] Table 1

[0052]

[0053] Table 2

[0054]

[0055] It can be seen from Table 1 that the use of a diaphragm structure with protrusions 3 can effectively improve the X-ray yield of the battery cell and improve the internal short circuit. However, the height of the protrusions 3 and / or the distance between the protrusions 3 exceeds the set range, which can easily lead to excessive thickness of the battery cell and reduce the volume energy density and cycle performance of the battery cell.

[0056] Battery

[0057] like Figure 5 As shown, a battery includes the separator 100 as described above and a pole piece 200 wound or stacked with the separator 100. The battery can be a lithium ion battery, a sodium ion battery, a magnesium ion battery, etc.

[0058] Electrical devices

[0059] An electrical device, comprising a battery as described above, wherein the electrical device may be a vehicle, a mobile phone, a portable device, a laptop computer, a ship, a spacecraft, an electric toy, an electric tool, etc. The vehicle may be a fuel vehicle, a gas vehicle or a new energy vehicle, and the new energy vehicle may be a pure electric vehicle, a hybrid vehicle or an extended-range vehicle, etc.; the spacecraft includes an airplane, a rocket, a space shuttle and a spacecraft, etc.; the electric toy includes a fixed or mobile electric toy, such as a game console, an electric car toy, an electric ship toy and an electric airplane toy, etc.; the electric tool includes a metal cutting electric tool, a grinding electric tool, an assembly electric tool and an electric tool for railways, such as an electric drill, an electric grinder, an electric wrench, an electric screwdriver, an electric hammer, an impact drill, a concrete vibrator and an electric planer, etc. The embodiments of the present application do not impose any special restrictions on the above-mentioned electrical devices.

[0060] 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 diaphragm, comprising a base film (1) and a coating (2) coated on the base film (1), characterized in that: Protrusions (3) are respectively arranged at both ends of the diaphragm, and an accommodation space is formed between the two protrusions (3), and the accommodation space is used to place a pole piece.

2. The diaphragm according to claim 1, characterized in that The width of the accommodation space in the width direction (W) of the diaphragm is set to 5 mm-80 mm.

3. The diaphragm according to claim 1, characterized in that The height of the protrusion (3) is H1, the thickness of the pole piece is H2, and H1 and H2 satisfy the relationship: H1-1μm≤H2≤H1+1μm, 40μm≤H2≤100μm.

4. The diaphragm according to claim 1, characterized in that The thickness of the pole piece is H2. In the length direction of the diaphragm, the interval between two adjacent protrusions (3) is L. The L and H2 satisfy the relationship: 1 / 3×H2≤L≤1 / 2×H2.

5. The diaphragm according to claim 1, characterized in that The protrusion (3) is formed by the base film (1), and the protrusion (3) passes through the coating layer (2) and is exposed at the coating layer (2).

6. The diaphragm according to claim 1, characterized in that The protrusion (3) is formed by the base film (1), and the coating (2) is coated on the protrusion (3).

7. The diaphragm according to claim 1, characterized in that The protrusion (3) is formed by the coating (2), and the protrusion (3) and the coating (2) are formed integrally.

8. The diaphragm according to claim 1, characterized in that The protrusion (3) is configured as one of a point-shaped structure, a water-drop-shaped structure, a linear structure and a polygonal structure.

9. A battery, characterized in that: The invention comprises a diaphragm (100) as claimed in any one of claims 1 to 8 and a pole piece (200) stacked or wound with the diaphragm (100).

10. An electrical device, characterized in that: Comprising the battery as claimed in claim 9.

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