Planar PTC heating body and battery module heating system

Abstract

The utility model relates to a planar PTC heating element and a battery module heating system, the planar PTC heating element comprises a heating element main body and a packaging body, the heating element main body comprises a PTC carbon film, an interdigital electrode and a current collector, the interdigital electrode is arranged between the PTC carbon film and the current collector, the interdigital electrode is respectively contacted with the PTC carbon film and the current collector in a conductive manner, the packaging body completely wraps the heating element main body, and the PTC carbon film is arranged on the packaging body. The packaging body comprises an inner packaging layer, a middle packaging layer and an outer packaging layer which are arranged from inside to outside, the inner packaging layer and the outer packaging layer are respectively made of insulating materials, and the middle packaging layer is made of metal. The planar PTC heating body is good in heating performance, high in safety and long in service life.

Description

Technical Field

[0001] The utility model belongs to the field of heating elements, and in particular relates to a planar PTC heating element and a battery module heating system. Background Art

[0002] Carbon-based PTC (Positive Temperature Coefficient) heating film is a new type of heating element with advantages such as automatic temperature regulation, safety, reliability, and low energy consumption. It is widely used in various heating devices, including battery module heating systems. However, the performance, reliability, and lifespan of battery modules at low temperatures are significantly reduced compared to those at room temperature. When using battery modules in low-temperature environments, a heating system must be used to heat the battery module to the appropriate temperature before charging and discharging can begin. Given the current demand for rapid heating in new energy sources, only high-power carbon-based PTC heating films can meet this requirement among thin-film heaters. However, existing heating films often have issues that affect their heating performance, safety, and lifespan, limiting their performance and application. For example, the electrodes in existing carbon-based PTC heating films are typically interdigitated electrodes. Due to the insufficient conductivity of interdigitated electrodes, high current operation requires a large printed area, which reduces the heating area of the heating film and reduces heating efficiency. Existing carbon-based PTC heating films are typically sealed with plastic film, which has poor water vapor barrier properties. When used in high-temperature and high-humidity environments, water vapor can penetrate the heating film through the plastic surface, causing power degradation or damage. Furthermore, existing PTC heating films are typically screen-printed with a carbon film on interdigital electrodes, resulting in uneven film thickness. The thinner portion located on the electrodes results in more noticeable heat generation and is prone to overheating. Summary of the Invention

[0003] The purpose of the utility model is to provide a planar PTC heating element with better heating performance, better safety and longer service life.

[0004] In order to achieve the above purpose, the technical solution adopted by the utility model is:

[0005] The utility model provides a planar PTC heating element, which includes a heating element body and a packaging body. The heating element body includes a PTC carbon film, interdigital electrodes and a current collector. The interdigital electrodes are located between the PTC carbon film and the current collector, and the interdigital electrodes are conductively contacted with the PTC carbon film and the current collector respectively. The packaging body completely covers the heating element body. The packaging body includes an inner packaging layer, a middle packaging layer and an outer packaging layer arranged from the inside to the outside. The materials of the inner packaging layer and the outer packaging layer are respectively insulating materials, and the material of the middle packaging layer is metal.

[0006] In the present invention, the interdigitated electrodes and the current collector are in physical contact, self-adhesive connection or connected via a conductive adhesive.

[0007] In the present invention, the conductive adhesive is an organic adhesive containing a conductive component and a film-forming component. Furthermore, the conductive adhesive can be any conventionally used conductive adhesive in the art, such as silver-based conductive adhesive, gold-based conductive adhesive, copper-based conductive adhesive, and carbon-based conductive adhesive. The resin matrix of the conductive adhesive includes adhesive systems such as epoxy resin, acrylate resin, polyurethane, silicone resin, polyimide resin, and phenolic resin.

[0008] In the present invention, the interdigital electrodes and the PTC carbon film are bonded to each other, and stable electrical bonding is formed after the interdigital electrode material or the PCT carbon film material penetrates into the rough interface of the other party.

[0009] In the present invention, the interdigitated electrode includes an integrally formed first connecting portion and a second connecting portion, at least the first connecting portion is in physical contact with the current collector, self-adhesive connection or connected by a conductive adhesive, and at least the second connecting portion is bonded to the PTC carbon film.

[0010] Furthermore, the first connecting portion is arranged on two opposite sides of the planar PTC carbon film, and the second connecting portion includes a plurality of electrode elements spaced apart on the surface of the PTC carbon film, each of the electrode elements is electrically connected to the first connecting portion.

[0011] Furthermore, the first connecting portion extends along an edge of the PTC carbon film, one end of the first connecting portion is aligned with one end of the PTC carbon film, and the other end extends out of the end of the PTC carbon film for connecting to a conductive component.

[0012] In the present invention, the material of the interdigital electrodes is silver paste, copper paste, tin paste, nickel paste, aluminum paste, carbon paste or conductive polymer.

[0013] In the present invention, the material of the current collector is a single element metal, an alloy, a high-conductivity carbon material or a high-conductivity semiconductor.

[0014] In the present invention, the conductive component of the PTC carbon film is one or a mixture of graphite, conductive carbon black, carbon fiber, carbon nanotube, and graphene.

[0015] Furthermore, the PTC carbon film is a conductive film formed by melt blending of a conductive material and a phase change material or other additives, or a conductive film formed by dispersed blending of a conductive material with a polymer solution, a phase change material, a leveling agent, and a defoaming agent and then drying the film, or a conductive film prepared by a "papermaking" process by breaking up a conductive material and artificial synthetic fibers or natural fibers.

[0016] In the present invention, the thickness of the PTC carbon film is 1 μm to 1000 μm, for example, 1 μm, 5 μm, 10 μm, 20 μm, 50 μm, 100 μm, 200 μm, 300 μm, 500 μm, 600 μm, 700 μm, 800 μm, 900 μm, and 1000 μm.

[0017] In the present invention, the thickness of the current collector and the interdigital electrodes are independently 1 μm to 500 μm, for example, 1 μm, 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, and 50 μm.

[0018] In the present invention, the thickness of the inner encapsulation layer, the middle encapsulation layer and the outer encapsulation layer are independently 10μm to 1000μm, for example, 1μm, 5μm, 10μm, 20μm, 50μm, 100μm, 200μm, 300μm, 500μm, 600μm, 700μm, 800μm, 900μm, and 1000μm.

[0019] Furthermore, the thicknesses of the inner encapsulation layer, the middle encapsulation layer and the outer encapsulation layer are independently 10 μm to 500 μm, for example, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, and the thicknesses of the three are the same or different.

[0020] In the present invention, the inner encapsulation layer includes an upper inner encapsulation layer and a lower inner encapsulation layer, and the upper inner encapsulation layer and the lower inner encapsulation layer are respectively arranged on the upper and lower surfaces of the heating body. The surrounding edges of the upper inner encapsulation layer and the lower inner encapsulation layer are flush with the surrounding edges of the heating body, or the surrounding edges of the upper inner encapsulation layer and the lower inner encapsulation layer respectively exceed the surrounding edges of the heating body and are connected to each other.

[0021] In the present invention, the middle encapsulation layer includes an upper middle encapsulation layer and a lower middle encapsulation layer, and the upper middle encapsulation layer and the lower middle encapsulation layer are respectively arranged on the upper and lower surfaces of the inner encapsulation layer, and the four edges of the upper middle encapsulation layer and the lower middle encapsulation layer are flush with the four edges of the inner encapsulation layer, or the four edges of the upper middle encapsulation layer and the lower middle encapsulation layer respectively exceed the four edges of the inner encapsulation layer and are connected to each other.

[0022] Preferably, at least the upper inner packaging layer and the lower inner packaging layer extend at least 2 mm beyond the area where the PTC carbon film and the interdigital electrodes are located to ensure that the edges of the area where the PTC carbon film and the interdigital electrodes are located are not exposed, preferably exceeding 2 to 10 mm.

[0023] In the present invention, the outer packaging layer includes an upper outer packaging layer and a lower outer packaging layer, and the upper outer packaging layer and the lower outer packaging layer are respectively arranged on the upper and lower surfaces of the middle packaging layer, and the four edges of the upper outer packaging layer and the lower outer packaging layer are flush with the four edges of the middle packaging layer, or the four edges of the upper outer packaging layer and the lower outer packaging layer respectively exceed the four edges of the middle packaging layer and are connected to each other.

[0024] Preferably, the outer packaging layer should extend at least 2 mm beyond the periphery of the middle packaging layer to ensure that the edge of the middle packaging layer is not exposed, preferably extending 2 to 10 mm. The outer packaging layer can be formed in one step or in multiple steps.

[0025] In the present invention, the packaging body also includes a first bonding layer arranged between the inner packaging layer and the heating element, a second bonding layer arranged between the middle packaging layer and the inner packaging layer, and a third bonding layer arranged between the outer packaging layer and the middle packaging layer. The materials constituting the first bonding layer, the second bonding layer, and the third bonding layer are independently thermoplastic bonding materials, thermosetting bonding materials, or pressure-sensitive bonding materials.

[0026] Furthermore, the thermoplastic adhesive material is a modified or unmodified polyolefin, polyamide, cellulose, polyether, polyester or aromatic heterocyclic polymer with a melting point of 60 to 300°C; the thermosetting adhesive material is a modified or unmodified silicone resin, polyolefin resin, phenolic resin, epoxy resin, amino resin, polyurethane resin, unsaturated polyester, acrylic resin or natural and synthetic rubber resin containing a cross-linking agent; the pressure-sensitive adhesive material is a silicone pressure-sensitive adhesive or a fluorine-modified hydrophobic pressure-sensitive adhesive.

[0027] According to some embodiments, the inner encapsulation layer includes an upper inner encapsulation layer and a lower inner encapsulation layer, and the four edges of the upper inner encapsulation layer are sealed to the four edges of the lower inner encapsulation layer; the middle encapsulation layer includes an upper middle encapsulation layer stacked on the side surface of the upper inner encapsulation layer away from the heating body, and a lower middle encapsulation layer stacked on the side surface of the lower inner encapsulation layer away from the heating body; the outer encapsulation layer includes an upper outer encapsulation layer stacked on the side surface of the upper middle encapsulation layer away from the upper inner encapsulation layer, and a lower outer encapsulation layer stacked on the side surface of the lower middle encapsulation layer away from the lower inner encapsulation layer, and the four edges of the upper middle encapsulation layer are sealed to the four edges of the lower outer encapsulation layer.

[0028] Furthermore, the packaging body also includes a first adhesive layer arranged between the upper inner packaging layer and the lower inner packaging layer, which can at least seal and fix the four edges of the upper inner packaging layer and the four edges of the lower inner packaging layer; an upper second adhesive layer arranged between the upper inner packaging layer and the upper middle packaging layer, and / or a lower second adhesive layer arranged between the lower inner packaging layer and the lower middle packaging layer; an upper third adhesive layer arranged between the upper outer packaging layer and the upper middle packaging layer, and / or a lower third adhesive layer arranged between the lower outer packaging layer and the upper middle packaging layer; the upper third adhesive layer and / or the lower third adhesive layer can at least seal and fix the four edges of the upper outer packaging layer and the four edges of the lower outer packaging layer.

[0029] In the present invention, the materials of the inner encapsulation layer and the outer encapsulation layer are independently modified or unmodified polyimide, modified or unmodified polyethylene terephthalate, modified or unmodified polypropylene, modified or unmodified polyethylene, modified or unmodified polyvinyl chloride, modified or unmodified epoxy resin, modified or unmodified phenolic resin or modified or unmodified silicone rubber.

[0030] In some embodiments of the present invention, the inner packaging layer and the outer packaging layer are independently composed of PI film, BOPP film, PET film, PVC film, BOPA film, CPP film, PC film or flame retardant cloth.

[0031] In the present invention, the middle packaging layer is made of metal foil, or the middle packaging layer is a metal plating layer formed on the inner packaging layer and / or the outer packaging layer.

[0032] In the present invention, the material of the middle packaging layer is aluminum, copper, nickel, tin, copper or alloys thereof.

[0033] In some embodiments of the present invention, the middle packaging layer is made of metal foil.

[0034] Furthermore, the metal foil can be any one of aluminum foil, copper foil, stainless steel foil, nickel foil, tin foil, and nickel-plated copper foil, preferably aluminum foil.

[0035] In other embodiments, the middle packaging layer is a metal plating layer formed on the inner packaging layer and / or the outer packaging layer.

[0036] In the present invention, the material of the current collector is aluminum, copper, nickel, tin, iron or alloys thereof, high-conductivity carbon material or high-conductivity polymer.

[0037] In the present invention, the planar PTC heating element further includes a conductive component for conductively connecting the current collector to an external power source, one end of the conductive component is conductively and fixedly connected to the current collector, and the other end of the conductive component is exposed to the outside of the package.

[0038] Furthermore, the conductive component may be a plug, a wire, a connecting harness, etc. The conductive component may be partially encapsulated inside the package and partially outside the package, and the periphery of the conductive component may be adhered with silicone for sealing and insulation.

[0039] The utility model also provides a battery module heating system, which includes a heated battery core and the above-mentioned planar PTC heating element.

[0040] Furthermore, the planar PTC heating element is wrapped and pasted on the outer surface of the heated battery core, or the planar PTC heating element is pasted on the inner surface of the enclosure, and the enclosure is arranged around the outside of the heated battery core, so that the planar PTC heating element is in physical contact with the surface of the heated battery core.

[0041] According to some embodiments, there is an adhesive layer between the heated battery core and the planar PTC heating element, and the planar PTC heating element is adhered to the battery core by the adhesive.

[0042] According to other embodiments, the battery cell and the planar PTC heating element are in direct contact, and a panel is provided on the outside of the battery cell and the planar PTC heating element, and physical contact between the battery cell and the planar PTC heating element is achieved through the panel. A thermal insulation cotton layer can be selectively provided on the inner surface of the panel, and a glue layer is provided between the thermal insulation cotton layer and the inner surface of the panel, and the thermal insulation cotton layer is adhered to the inner surface of the panel through the glue layer. The planar PTC heating element is directly sandwiched between the battery cell and the thermal insulation cotton layer, and the planar PTC heating element is movable relative to the battery cell, thereby avoiding the risk of breakage of the planar PTC heating element due to expansion of the battery cell.

[0043] Furthermore, the enclosure is an aluminum plate, a steel plate or a hard plastic plate.

[0044] The planar PTC heating element of this utility model can improve the electrode conductivity of the carbon-based PTC heating film, reduce the printing area of the interdigitated electrodes, and increase the heating area, thereby improving the heating efficiency of the heating film and meeting the needs of electric heating equipment for efficient heating. The planar PTC heating element of this utility model can also block water vapor, reducing the impact of water vapor on the PTC carbon film. At the same time, the outer packaging layer isolates the metal layer from the air, preventing the induced current generated by the packaging layer during power-on and power-off from discharging into the air, thereby improving safety and reliability, and meeting the safety and reliability requirements of new energy equipment, medical equipment, electronic equipment, etc.

[0045] Certain solutions of this utility model, by post-fabricating the electrodes of the planar PTC heating element on the carbon film, can also solve the problem of carbon film steps when the carbon film is printed on the electrode of traditional heating films. This ensures uniform heating of the carbon film and avoids overheating, thereby extending the service life of the heating film and meeting the durability and stability requirements of various equipment. Therefore, the planar PTC heating element of this utility model has broad market demand and good application prospects.

[0046] Due to the application of the above technical solution, the utility model has the following advantages compared with the prior art:

[0047] The planar PTC heating element of this utility model increases the electrode current carrying capacity by attaching a current collector to the interdigital electrodes, thereby reducing the printed area of the interdigital electrodes, thereby increasing the heating area and improving heating efficiency. The utility model uses a three-layer composite packaging structure to improve the sealing effect of isolating water vapor while preventing the induction current discharge caused by the addition of metal foil. The utility model can avoid the formation of steps in the carbon film, reducing the risk of abnormal fracture of the carbon film at the steps, thereby improving heating performance, safety and service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0049] It should be noted that in order to fully display the structure in the drawings, the proportional relationship in the drawings has been adaptively adjusted, but it does not represent the proportional relationship of the structures of the various parts in actual use, or the proportional relationship in the drawings as a factor in limiting the scope of protection of the present invention.

[0050] Figure 1 Schematic diagram of part of the structure of the planar PTC heating element of Example 1 (the upper inner packaging layer, the upper middle packaging layer and the upper outer packaging layer are omitted);

[0051] Figure 2 This is an exploded view of the planar PTC heating element of Example 1 from one perspective;

[0052] Figure 3 This is an exploded view of the planar PTC heating element of Example 1 from another perspective.

[0053] Among them, 1. PTC carbon film; 21. First part; 22. Second part; 23. Electrode element; 31. First current collector; 31. Second current collector; 411. Upper inner packaging layer; 412. Lower inner packaging layer; 421. Upper middle packaging layer; 422. Lower middle packaging layer; 431. Upper outer packaging layer; 432. Lower outer packaging layer; 441. First bonding layer; 4421. Upper second bonding layer; 4422. Lower second bonding layer; 4431. Upper third bonding layer; 4432. Lower third bonding layer; 51. First conductive component; 52. Second conductive component. DETAILED DESCRIPTION

[0054] The present invention will be further described below with reference to the embodiments shown in the accompanying drawings.

[0055] Hereinafter, only certain exemplary embodiments are briefly described. As will be appreciated by those skilled in the art, the described embodiments may be modified in various ways without departing from the spirit or scope of the embodiments of the present invention. Therefore, the drawings and description are to be regarded as illustrative in nature and not restrictive.

[0056] In the description of this utility model, it should be noted that the terms "upper" and "lower" are used in accordance with the Figure 2 The terms "inside" and "outside" are defined by the distance relative to the PTC carbon film 1, where "inside" refers to a position close to the PTC carbon film 1 and "outside" refers to a position far from the PTC carbon film 1. The above directional terms are merely for the purpose of facilitating the description of the present invention and simplifying the description. They do not indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limiting the present invention.

[0057] The drawings provided in the present invention are merely schematic diagrams of the structure of the planar PTC heater for the convenience of readers, and do not represent any limitation on the structure of the planar PTC heater.

[0058] In the embodiments of the present invention, unless otherwise specified or limited, the terms "installed," "connected," "connected," "fixed," etc. should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integration. Those skilled in the art will understand the specific meanings of the above terms in the embodiments of the present invention based on specific circumstances.

[0059] In order to simplify the disclosure of the embodiments of the present invention, the components and configurations of specific examples are described below. Of course, these are merely examples and are not intended to limit the embodiments of the present invention. The specifications and models of the components can be adjusted according to actual needs.

[0060] Example 1

[0061] like Figures 1 to 3 As shown, this embodiment provides a planar PTC heating element, which includes a PTC carbon film 1, interdigital electrodes, a current collector, a package and a conductive component. The PTC carbon film 1, interdigital electrodes and the current collector are packaged in the package.

[0062] In this embodiment, the PTC carbon film 1 has a length of 450 mm, a width of 150 mm, and a thickness of 0.01 mm.

[0063] In this embodiment, the interdigitated electrodes are made of silver paste and include an integrally formed first and second connecting portions. The first connecting portion comprises a first portion 21 and a second portion 22 disposed on opposite sides of the PTC carbon film 1. The first and second portions 21 and 22 are each 480 mm long, 4 mm wide, and 0.005 mm thick. The first and second portions 21 and 22 are located on opposite long edges of the upper surface of the PTC carbon film 1, extending from one end of the PTC carbon film 1 to the other and extending 30 mm beyond the other end. The second connecting portion comprises a plurality of electrode elements 23 spaced apart on the surface of the PTC carbon film. Each electrode element 23 is electrically connected to the first connecting portion. The electrode elements 23 are equally spaced along the length of the PTC carbon film 1 and alternately connected to one of the first and second portions 21 and 22. Each electrode element 23 extends parallel to the width of the PTC carbon film 1. Each electrode element 23 has a length of 140 mm, a width of 0.5 mm, and a thickness of 0.005 mm.

[0064] In this embodiment, the current collector is a copper bar, including a first current collector 31 and a second current collector 32. The length of the first current collector 31 and the second current collector 32 are 480 mm, the width is 4 mm, and the thickness is 0.02 mm. The first current collector 31 is covered on the upper surface of the first part 21 by conductive adhesive, and the first current collector 31 extends from one end of the first part 21 to the other end. The second current collector 32 is covered on the upper surface of the second part 22 by conductive adhesive, and the second current collector 33 extends from one end of the second part 22 to the other end.

[0065] In this embodiment, the package body includes an upper half and a lower half. The upper half includes an upper outer packaging layer 431, an upper middle packaging layer 421 and an upper inner packaging layer 411 stacked in sequence from top to bottom. The lower half includes a lower inner packaging layer 412, a lower middle packaging layer 422 and a lower outer packaging layer 432 stacked in sequence from top to bottom.

[0066] Specifically, the lower inner packaging layer 412 is located below the PTC carbon film 1. The lower inner packaging layer 412 is a polyimide film with a length of 490 mm, a width of 160 mm, and a thickness of 0.05 mm. In the width direction of the lower inner packaging layer 412, the PTC carbon film 1 is centered, and both sides of the PTC carbon film 1 extend by 5 mm on both sides of the PTC carbon film 1; in the length direction of the PTC carbon film 1, one end of the PTC carbon film 1 extends by 5 mm from the edge of the PTC carbon film 1, and the other end extends by 35 mm from the edge of the PTC carbon film 1. The parts of the first part 21 and the second part 22 that extend beyond the PTC carbon film 1 fall on the lower inner packaging layer 412, and the other end of the lower inner packaging layer 412 extends by 5 mm from the ends of the first part 21 and the second part 22. The upper inner encapsulation layer 411 has the same dimensions as the lower encapsulation layer 412. The upper inner encapsulation layer 411 is located above the current collector. A first adhesive layer 4411 is provided on the lower surface of the upper inner encapsulation layer 411 for bonding the upper inner encapsulation layer 411 and the lower inner encapsulation layer 412, thereby encapsulating the PTC carbon film 1, the interdigitated electrodes, and the current collector between the upper inner encapsulation layer 411 and the lower inner encapsulation layer 412. The upper middle encapsulation layer 421 and the lower middle encapsulation layer 422 have the same dimensions as the upper inner encapsulation layer 411. An upper second adhesive layer 4421 is provided on the lower surface of the upper middle encapsulation layer 421 for bonding the upper middle encapsulation layer 412 to the upper inner encapsulation layer 411. A lower second adhesive layer 4422 is provided on the upper surface of the lower middle encapsulation layer 422 for bonding the lower middle encapsulation layer 422 to the lower inner encapsulation layer 412. The length of the upper outer packaging layer 431 and the lower outer packaging layer 432 are 500 mm, the width is 170 mm, and the thickness is 0.05 mm respectively. The four edges of the upper outer packaging layer 431 and the lower outer packaging layer 432 extend by 5 mm from the four edges of the upper middle packaging layer 321 and the lower middle packaging layer 322 respectively. An upper third adhesive layer 4431 for bonding the upper outer packaging layer 431 and the upper middle packaging layer 421 is provided on the lower surface of the upper outer packaging layer 431. A lower third adhesive layer 4432 for bonding the lower outer packaging layer 432 and the lower middle packaging layer 422 is provided on the upper surface of the lower outer packaging layer 432. The four edges of the upper outer packaging layer 431 are bonded to the four edges of the lower outer packaging layer 432 through the upper third adhesive layer 4431 and the lower third adhesive layer 4432. In this embodiment, the upper inner packaging layer 411 and the first adhesive layer 4411 are polyimide tapes with modified acrylic epoxy resin adhesive coated on the inner surface, the lower inner packaging layer 412 is a polyimide film, which can be used as a substrate layer when preparing a PTC carbon film, the upper middle packaging layer 421 and the upper second adhesive layer 4421 are aluminum foil tapes with adhesive coated on the inner surface, the lower middle packaging layer 422 and the lower second adhesive layer 4422 are aluminum foil tapes with adhesive coated on the inner surface, the upper outer packaging layer 431 and the upper third adhesive layer 4431 are BOPP tapes with adhesive coated on the inner surface, and the lower outer packaging layer 432 and the lower third adhesive layer 4432 are BOPP tapes with adhesive coated on the inner surface.

[0067] In this embodiment, the conductive component includes a first conductive component 51 that is conductively connected to the end of the first current collector 31 that extends beyond the PTC carbon film 1, and a second conductive component 52 that is conductively connected to the end of the second current collector 32 that extends beyond the PTC carbon film 1. The connection between the first conductive component 51 and the first current collector 31 and the connection between the second conductive component 52 and the second current collector 32 are respectively sealed and insulated with the package body by insulating materials. The first conductive component 51 and the second conductive component 52 are wire harnesses used to connect the electrodes to an external power supply.

[0068] The preparation method of the planar PTC heating element of this embodiment is as follows:

[0069] (1) A polyimide film is taken as the lower inner encapsulation layer 412 (which can also serve as the substrate layer for forming the carbon film) according to the above-mentioned size requirements, and its surface is cleaned to remove surface impurities and improve adhesion;

[0070] (2) Printing a layer of carbon paste on the upper surface of the polyimide film according to the above-mentioned size requirements by screen printing to form a PTC carbon film 1;

[0071] (3) a layer of silver paste is printed on the PTC carbon film 1 by screen printing, and dried at 120° C. for 30 minutes to solidify the silver paste to form a first portion 21, a second portion 22, and a plurality of electrode elements 23. The first portion 21 and the second portion 22 extend onto the polyimide film;

[0072] (4) Using a conductive pressure-sensitive adhesive to attach the first current collector 31 to the first portion 21, and using a conductive pressure-sensitive adhesive to attach the second current collector 32 to the second portion 22;

[0073] (5) Covering and pasting a polyimide tape on the upper surface of the heating component obtained in the above step (4), aligning the edges of the polyimide tape with the edges of the polyimide film and sealing and bonding them together; covering and pasting a layer of aluminum foil tape on the upper surface of the polyimide tape; covering and pasting a layer of aluminum foil tape on the lower surface of the polyimide film; the upper and lower layers of aluminum foil tape are completely aligned with the polyimide tape and the polyimide film respectively; pasting a layer of BOPP tape on the outer surfaces of the upper and lower layers of aluminum foil tape respectively; the four sides of the upper and lower layers of BOPP tape extend beyond the edge of the aluminum foil tape by 5 mm respectively; aligning and sealing and bonding the four sides of the upper and lower layers of BOPP tape;

[0074] (6) A terminal is made on one end of the first current collector 31 extending to the polyimide film and the first conductive component 51 is welded thereto. A terminal is made on one end of the second current collector 32 extending to the polyimide film and the second conductive component 52 is welded thereto. The connection is sealed and insulated with silicone and a packaging body.

[0075] Example 2

[0076] The structure of the planar PTC heating element provided in this embodiment is basically the same as that of the planar PTC heating element in Example 1, and the preparation method is slightly different from that in Example 1. During the preparation process of this embodiment, the PTC carbon film 1, the interdigitated electrode and the current collector are formed into a whole as the heating element body, the upper outer packaging layer 431, the upper middle packaging layer 421 and the upper inner packaging layer 411 are pre-bonded into a whole as the upper half of the packaging body, and the lower inner packaging layer 412, the lower middle packaging layer 422 and the lower outer packaging layer 432 are pre-bonded into a whole as the lower half of the packaging body, and then the upper half and the lower half are pasted to the opposite side surfaces of the heating element body and the four edges of the upper half and the lower half are aligned and sealed.

[0077] Example 3

[0078] This embodiment provides a battery module heating system, comprising a battery cell, and the planar PTC heating element of Example 1, a thermal insulation layer, and a panel arranged in order from the battery cell outward. In this embodiment, an adhesive layer is provided between the thermal insulation layer and the panel, affixing the thermal insulation layer to the panel. The planar PTC heating element is directly sandwiched between the battery cell and the thermal insulation layer, thereby preventing the risk of fracture of the planar PTC heating element due to battery cell expansion. The panel is made of a hard plastic plate.

[0079] The above embodiments are intended only to illustrate the technical concepts and features of the present invention. Their purpose is to enable those familiar with the art to understand the contents of the present invention and implement them accordingly. They are not intended to limit the scope of protection of the present invention. Any equivalent changes or modifications based on the spirit of the present invention are intended to be included in the scope of protection of the present invention.

Claims

1. A planar PTC heating element, characterized in that: The planar PTC heating element comprises a heating element body and a packaging body, wherein the heating element body comprises a PTC carbon film, interdigital electrodes and a current collector. The interdigital electrodes are located between the PTC carbon film and the current collector, and the interdigital electrodes are in conductive contact with the PTC carbon film and the current collector, respectively. The packaging body completely covers the heating element body, and the packaging body includes an inner packaging layer, a middle packaging layer and an outer packaging layer arranged from the inside to the outside. The materials of the inner packaging layer and the outer packaging layer are respectively insulating materials, and the material of the middle packaging layer is metal.

2. The planar PTC heating element according to claim 1, characterized in that: The interdigitated electrodes and the current collector are in physical contact, self-adhesive connection, or connected via a conductive adhesive, and the interdigitated electrodes and the PTC carbon film are bonded to each other.

3. The planar PTC heating element according to claim 2, characterized in that: The interdigitated electrode includes an integrally formed first connecting portion and a second connecting portion, at least the first connecting portion is in physical contact with the current collector, self-adhesive connection or connected via a conductive adhesive, and at least the second connecting portion is bonded to the PTC carbon film.

4. The planar PTC heating element according to claim 3, characterized in that: The first connecting portion is arranged on two opposite sides of the planar PTC carbon film, and the second connecting portion includes a plurality of electrode elements spaced apart on the surface of the PTC carbon film, each of the electrode elements is electrically connected to the first connecting portion.

5. The planar PTC heating element according to claim 1, characterized in that: The material of the interdigital electrodes is silver paste, tin paste, copper paste, nickel paste, aluminum paste, carbon paste or conductive polymer; And / or, the material of the current collector is a single metal, an alloy, a high-conductivity carbon material or a high-conductivity semiconductor; And / or, the conductive component of the PTC carbon film is one or a mixture of graphite, conductive carbon black, carbon fiber, carbon nanotubes, and graphene; and / or, the thickness of the PTC carbon film is 1 μm to 1000 μm; And / or, the thickness of the current collector and the interdigital electrode are independently 1 μm to 500 μm; And / or, the thickness of the inner encapsulation layer, the middle encapsulation layer and the outer encapsulation layer are independently 10 μm to 1000 μm.

6. The planar PTC heating element according to claim 1, characterized in that: The inner packaging layer includes an upper inner packaging layer and a lower inner packaging layer, and the upper inner packaging layer and the lower inner packaging layer are respectively arranged on the upper and lower surfaces of the heating body. The edges of the upper inner packaging layer and the lower inner packaging layer are flush with the edges of the heating body, or the edges of the upper inner packaging layer and the lower inner packaging layer respectively exceed the edges of the heating body and are connected to each other. and / or, the middle encapsulation layer includes an upper middle encapsulation layer and a lower middle encapsulation layer, the upper middle encapsulation layer and the lower middle encapsulation layer are respectively arranged on the upper and lower surfaces of the inner encapsulation layer, the peripheral edges of the upper middle encapsulation layer and the lower middle encapsulation layer are flush with the peripheral edges of the inner encapsulation layer, or the peripheral edges of the upper middle encapsulation layer and the lower middle encapsulation layer respectively exceed the peripheral edges of the inner encapsulation layer and are connected to each other, And / or, the outer packaging layer includes an upper outer packaging layer and a lower outer packaging layer, and the upper outer packaging layer and the lower outer packaging layer are respectively arranged on the upper and lower surfaces of the middle packaging layer, and the four edges of the upper outer packaging layer and the lower outer packaging layer are flush with the four edges of the middle packaging layer, or the four edges of the upper outer packaging layer and the lower outer packaging layer respectively exceed the four edges of the middle packaging layer and are connected to each other.

7. The planar PTC heating element according to claim 1, characterized in that: The packaging body also includes a first adhesive layer arranged between the inner packaging layer and the heating element, a second adhesive layer arranged between the middle packaging layer and the inner packaging layer, and a third adhesive layer arranged between the outer packaging layer and the middle packaging layer. The materials constituting the first adhesive layer, the second adhesive layer, and the third adhesive layer are independently thermoplastic adhesive materials, thermosetting adhesive materials, or pressure-sensitive adhesive materials. The thermoplastic adhesive material is a modified or unmodified polyolefin, polyamide, cellulose, polyether, polyester, or aromatic heterocyclic polymer with a melting point of 60 to 300°C; the thermosetting adhesive material is a modified or unmodified silicone resin, polyolefin resin, phenolic resin, epoxy resin, amino resin, polyurethane resin, unsaturated polyester, acrylic resin, or natural and synthetic rubber resin containing a cross-linking agent; the pressure-sensitive adhesive material is a silicone pressure-sensitive adhesive or a fluorine-modified hydrophobic pressure-sensitive adhesive.

8. The planar PTC heating element according to claim 1, characterized in that: The materials of the inner encapsulation layer and the outer encapsulation layer are independently modified or unmodified polyimide, modified or unmodified polyethylene terephthalate, modified or unmodified polypropylene, modified or unmodified polyethylene, modified or unmodified polyvinyl chloride, modified or unmodified epoxy resin, modified or unmodified phenolic resin or modified or unmodified silicone rubber; And / or, the middle encapsulation layer is composed of metal foil, or the middle encapsulation layer is a metal plating layer formed on the inner encapsulation layer and / or the outer encapsulation layer; And / or, the middle encapsulation layer is made of aluminum, copper, nickel, tin, copper or alloys thereof; And / or, the current collector is made of aluminum, copper, nickel, tin, iron or alloys thereof, high-conductivity carbon material or high-conductivity polymer; And / or, the PTC carbon film is a conductive film formed by melt blending a conductive material with a phase change material or other additives, or a conductive film formed by dispersed blending a conductive material with a polymer solution, a phase change material, a leveling agent, and a defoaming agent and then drying the film, or a conductive film prepared by a "papermaking" process by breaking up a conductive material with artificial synthetic fibers or natural fibers; And / or, the planar PTC heating element further includes a conducting component for conductively connecting the current collector to an external power source, one end of the conducting component is conductively and fixedly connected to the current collector, and the other end of the conducting component is exposed to the outside of the package.

9. A battery module heating system, characterized in that: The battery module heating system includes a heated battery cell and a planar PTC heating element according to any one of claims 1 to 8.

10. The battery module heating system according to claim 9, characterized in that: The planar PTC heating element is wrapped and pasted on the outer surface of the heated battery core, or the planar PTC heating element is pasted on the inner surface of the enclosure, and the enclosure is arranged around the outside of the heated battery core so that the planar PTC heating element is in physical contact with the surface of the heated battery core.

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