Lithium battery containing high-thermal-conductivity and high-heat-dissipation cell mylar film

Abstract

The utility model provides a lithium battery containing a high-heat-conduction and high-heat-dissipation cell mylar film. The lithium battery comprises a shell, a top cover, a bottom supporting sheet and a roll core arranged in the shell and connected with the top cover, and further comprises a mylar film and a graphene coating which are located in the shell and tightly attached to the surface of the roll core, the inner surface of the graphene coating clings to the outer surface of the mylar film, and the outer surface of the graphene coating clings to the inner surface of the shell; heat dissipation holes are formed in the front surface of the mylar film, and holes for electrolyte to pass through are formed in the lower surface of the mylar film; according to the utility model, the holes are designed on the mylar film, so that the heat dissipation area and the heat diffusion channels are greatly increased, and the problem that the temperature is gathered and is not easy to diffuse is avoided. Furthermore, the surface of the mylar film is uniformly coated with a graphene coating, Joule heat and temperature rise generated by charging and discharging of the lithium battery are absorbed and diffused, the effect of cooling the interior of the battery is achieved, the temperature equalization performance in the battery cell is greatly improved, and the graphene coating plays an important role in fast charging characteristic, service life improvement and safety protection of the lithium battery.

Description

Technical Field

[0001] This utility model relates to the field of battery equipment technology, and in particular to a lithium battery containing a Mylar membrane with high thermal conductivity and high heat dissipation. Background Technology

[0002] With the rapid increase in demand for new energy sources in modern society, the requirements for the electrical and safety performance of lithium-ion batteries are also becoming increasingly stringent. Insufficient heat dissipation, leading to safety hazards and lifespan degradation, greatly limits their performance and application scope. Therefore, improving the heat dissipation performance of lithium-ion batteries has a significant impact on their application.

[0003] Currently, in the production process of square lithium batteries, the wound core needs to be wrapped with a soft and flexible insulating film before being placed into the casing. This ensures that the cell is completely insulated and prevents the hard casing from affecting the wound core, especially its safety performance. Currently, lithium battery cores are mostly wrapped with PP Mylar film, which provides electronic insulation and prevents short circuits caused by accidental impacts that could puncture the separator. This serves a crucial role in battery safety protection.

[0004] Although the Mylar membrane structure of lithium batteries is relatively simple, using thermoplastic molding of PP material to completely cover the core, thus meeting the shell requirements, PP film material itself has very poor thermal conductivity, only 0.22 W / mK. Furthermore, lithium batteries continuously generate heat and experience temperature rises during charging and discharging; this sustained temperature accumulation is difficult to dissipate, potentially leading to electrolyte decomposition, decreased charging rate, reduced battery life, and even safety issues such as lithium plating. Low-defect, large-diameter graphene, on the other hand, has a thermal conductivity of 5300 W / mK, 20,000 times that of PP, making it an excellent thermal conductor.

[0005] Therefore, this invention designs a porous Mylar membrane structure with a graphene coating that has high thermal conductivity and high heat dissipation, in order to improve the safety and rate performance of the battery cell. Utility Model Content

[0006] This invention provides a lithium battery containing a Mylar film with high thermal conductivity and high heat dissipation, the purpose of which is to solve the above-mentioned problems existing in the background art.

[0007] To achieve the above objectives, embodiments of this utility model provide a lithium battery containing a Mylar film with high thermal conductivity and high heat dissipation, including a shell, a top cover, a bottom support sheet, and a core placed inside the shell and connected to the top cover, and also including a Mylar film located inside the shell and in close contact with the surface of the core, and a graphene coating.

[0008] The inner surface of the graphene coating is in close contact with the outer surface of the Mylar membrane, and the outer surface of the graphene coating is in close contact with the inner surface of the outer shell;

[0009] The front surface of the Mylar membrane is provided with heat dissipation holes, and the lower surface of the Mylar membrane is provided with holes for electrolyte to pass through. Since the electrolyte will accumulate at the bottom under the action of gravity, it is easy to wet. The holes facilitate the absorption of electrolyte by the electrode and reduce obstruction.

[0010] According to one aspect of this utility model, the heat dissipation hole is circular with a size of 0.1–3 mm; the hole for electrolyte passage has a size of one-third to one-quarter of the heat dissipation hole. The shape of the hole for electrolyte passage includes circular and rectangular. Preferably, the shape of the hole for electrolyte passage is circular.

[0011] According to one aspect of this utility model, the heat dissipation holes are arranged in a square matrix; 16-160 holes / cm 2 .

[0012] According to one aspect of the present invention, the Mylar membrane is in the shape of an open cuboid.

[0013] According to one aspect of the present invention, the side surface of the Mylar membrane is provided with heat dissipation holes.

[0014] According to one aspect of the present invention, the thickness of the Mylar membrane is 0.2 mm.

[0015] According to one aspect of this invention, the thickness of the graphene coating is 0.1–0.5 mm; the graphene content in the graphene coating is 0.1–1.0 g / m³. 2 .

[0016] According to one aspect of the present invention, the preparation process of the graphene coating is as follows: graphene powder and resin binder are dispersed in polyvinylpyrrolidone solvent at a mass ratio of 1:3 to 3:1 to obtain a slurry, which is then coated onto a substrate.

[0017] According to one aspect of this utility model, the graphene powder contains graphene flakes with a diameter > 10 μm, a number of layers < 6, and a specific surface area > 200 m². 2 / g.

[0018] According to one aspect of the present invention, the resin adhesive is prepared by in-situ polymerization of functionalized monomers.

[0019] According to one aspect of this invention, the monomer includes at least one of acrylic acid, acrylonitrile, and propylene resin. Small molecules can improve dispersion performance, while large molecules and cyano groups improve adhesion, thereby enhancing the mechanical and electrical properties of the coating, electrolyte resistance, and preventing peeling.

[0020] The above-mentioned solution of this utility model has the following beneficial effects:

[0021] This invention significantly increases the heat dissipation area and heat diffusion channels by designing a porous Mylar membrane, avoiding the problem of heat accumulation and difficulty in dissipation. Furthermore, a graphene coating is uniformly applied to the surface of the porous Mylar membrane, absorbing and diffusing the Joule heat and temperature rise generated during lithium battery charging and discharging, achieving a cooling effect inside the battery. This greatly improves the internal temperature uniformity of the cell and plays a crucial role in enhancing the fast-charging characteristics, lifespan, and safety protection of lithium batteries. Attached Figure Description

[0022] Figure 1 This is a front view structural diagram of the present invention;

[0023] Figure 2 This is a schematic diagram of the unfolded Mylar membrane structure of the battery cell of this utility model.

[0024] [Explanation of Labels in the Attached Image]

[0025] 1-Outer shell; 2-Top cover; 3-Roll core; 4-Heat dissipation hole; 5-Graphene coating; 6-Bottom support plate; 7-Side surface of Mylar membrane; 8-Lower surface of Mylar membrane; 9-Front surface of Mylar membrane. Detailed Implementation

[0026] To make the technical problems, technical solutions and advantages of this utility model clearer, a detailed description will be given below in conjunction with the accompanying drawings and specific embodiments.

[0027] In the description of this application, it should be understood that the terms "center," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating the orientation or positional relationship shown in the accompanying drawings, are used only for the convenience of describing this patent and simplifying the description, and do not indicate or imply that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this patent. In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "setting" should be interpreted broadly. For example, they can refer to a fixed connection or setting, a detachable connection or setting, or an integral connection or setting. Those skilled in the art can understand the specific meaning of the above terms in this patent according to the specific circumstances.

[0028] The existing lithium battery Mylar membrane uses PP film material, which has a very poor thermal conductivity of only 0.22 W / mK. Furthermore, lithium batteries continuously generate heat and experience temperature increases during charging and discharging. If this sustained temperature buildup is difficult to dissipate, it can lead to electrolyte decomposition, decreased charging rate, battery life reduction, and even lithium plating safety issues.

[0029] This invention provides a lithium battery containing a Mylar film with high thermal conductivity and high heat dissipation. A front structural diagram is shown below. Figure 1 As shown, it includes an outer shell 1, a top cover 2, a bottom support 6, and a core 3 placed inside the outer shell 1 and connected to the top cover 2. It also includes a Mylar film located inside the outer shell 1 and tightly attached to the surface of the core 3 (as shown in the schematic diagram of the unfolded structure). Figure 2 (as shown) and graphene coating 5;

[0030] The inner surface of the graphene coating 5 is in close contact with the outer surface of the Mylar membrane, and the outer surface of the graphene coating is in close contact with the inner surface of the outer shell;

[0031] The Mylar membrane has heat dissipation holes 4 on its front surface 9 and holes for electrolyte to pass through on its lower surface 8. Since the electrolyte will accumulate at the bottom under the action of gravity, it is easy to wet the electrolyte. The holes facilitate the absorption of electrolyte by the electrode and reduce obstruction.

[0032] According to one aspect of this utility model, the heat dissipation hole 4 is circular with a size of 0.1–3 mm; the hole for electrolyte passage has a size of one-third to one-quarter of the heat dissipation hole. The shape of the hole for electrolyte passage includes circular and rectangular. Preferably, the shape of the hole for electrolyte passage is circular.

[0033] According to one aspect of this utility model, the heat dissipation holes 4 are arranged in a square matrix; 16-160 holes / cm 2 .

[0034] According to one aspect of the present invention, the Mylar membrane is in the shape of an open cuboid.

[0035] According to one aspect of the present invention, the side surface 7 of the Mylar membrane is provided with heat dissipation holes 4.

[0036] According to one aspect of the present invention, the thickness of the Mylar membrane is 0.2 mm.

[0037] According to one aspect of this invention, the thickness of the graphene coating 5 is 0.1–0.5 mm; the graphene content in the graphene coating 5 is 0.1–1.0 g / m³. 2 .

[0038] According to one aspect of the present invention, the preparation process of the graphene coating 5 is as follows: graphene powder and resin binder are dispersed in polyvinylpyrrolidone solvent at a mass ratio of 1:3 to 3:1 to obtain a slurry, which is then coated onto a substrate.

[0039] According to one aspect of this utility model, the graphene powder contains graphene flakes with a diameter > 10 μm, a number of layers < 6, and a specific surface area > 200 m². 2 / g.

[0040] According to one aspect of the present invention, the resin adhesive is prepared by in-situ polymerization of functionalized monomers.

[0041] According to one aspect of the present invention, the monomer includes at least one of acrylic acid, acrylonitrile, and propylene ester.

[0042] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A lithium battery containing a Mylar film with high thermal conductivity and high heat dissipation, comprising a casing, a top cover, a bottom support, and a core disposed within the casing and connected to the top cover, characterized in that, It also includes a Mylar film located inside the casing and in close contact with the surface of the core, as well as a graphene coating; The inner surface of the graphene coating is in close contact with the outer surface of the Mylar membrane, and the outer surface of the graphene coating is in close contact with the inner surface of the outer shell; The front surface of the Mylar membrane is provided with heat dissipation holes, and the lower surface of the Mylar membrane is provided with holes for electrolyte to pass through.

2. A lithium battery containing a Mylar film with high thermal conductivity and high heat dissipation of the cell, as described in claim 1, is characterized in that, The heat dissipation holes are circular and have a size of 0.1 to 3 mm; the size of the holes for electrolyte passage is one-third to one-quarter of the diameter of the heat dissipation holes.

3. A lithium battery containing a Mylar film with high thermal conductivity and high heat dissipation of the cell, as described in claim 1, is characterized in that... The heat dissipation holes are arranged in a square matrix; 16~160 holes / cm 2 .

4. A lithium battery containing a Mylar film with high thermal conductivity and high heat dissipation of the cell according to claim 1, characterized in that, The melar membrane is an open cuboid shape.

5. A lithium battery containing a Mylar film with high thermal conductivity and high heat dissipation of the cell according to claim 1, characterized in that, The thickness of the Mylar membrane is 0.2 mm.

6. A lithium battery containing a Mylar film with high thermal conductivity and high heat dissipation of the cell according to claim 1, characterized in that, The thickness of the graphene coating is 0.1~0.5 mm.

7. A lithium battery containing a Mylar film with high thermal conductivity and high heat dissipation of the cell according to claim 1, characterized in that, The graphene coating has a graphene sheet diameter > 10 μm, a number of layers < 6, and a specific surface area > 200 m². 2 / g.

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