Electric heating film and preparation method thereof, battery unit, battery pack and electric equipment

Abstract

The invention provides an electric heating film and a preparation method thereof, a battery unit, a battery pack and electric equipment. The electric heating film comprises a base material; the heating coating is arranged on one surface of the base material, the heating coating comprises at least one heating layer and at least one conducting layer, the heating layers and the conducting layers are alternately arranged, and the heating layers are made of MOSH semiconductor materials. The electric heating film can comprehensively, uniformly and quickly heat an object to be heated, can realize higher electric heating conversion efficiency, and further improves the heating efficiency of the electric heating film.

Description

Technical Field

[0001] The present invention relates to the field of battery technology, and in particular to an electric heating film and a preparation method thereof, a battery cell, a battery pack and an electrical device. Background Art

[0002] With the rapid development of new energy vehicles and energy storage systems, lithium-ion batteries have attracted widespread attention due to their high energy density and long cycle life. However, at low temperatures (<0°C), the performance of lithium-ion batteries declines significantly: increased electrolyte viscosity leads to reduced ionic conductivity, delayed reaction kinetics of electrode active materials, and even the growth of lithium dendrites, resulting in capacity decay and safety hazards. Moreover, when the temperature drops to -20°C, the battery capacity decay can reach more than 30%, and the charging efficiency drops by 70%. These problems seriously restrict the endurance of new energy vehicles in cold regions.

[0003] In order to solve the above problems, a heating component is usually set up to heat the battery cells in a low temperature environment, so that the battery maintains good working performance. At present, traditional low-temperature heating technologies are mainly divided into external heating (PTC (resistance wire) heating, liquid circulation heating, electric heating film heating) and internal self-heating (such as pulse current excitation heating). Among them, internal heating technologies such as pulse heating can use the internal resistance of the battery to generate heat, but it will accelerate battery aging and increase safety risks. Therefore, compared with internal heating technology, external heating has the advantage of working independently of the battery, and the engineering implementation is simpler. It has become the core module of the current power battery thermal management system. However, the above-mentioned external heating methods also have some problems, such as uneven heating and slow heating rate. Summary of the Invention

[0004] The present invention aims to solve at least one of the technical problems in the related art to a certain extent. To this end, one object of the present invention is to provide an electric heating film that heats evenly, has a fast heating rate, or has a high electrothermal conversion efficiency.

[0005] In one aspect, the present invention provides an electric heating film. According to an embodiment of the present invention, the electric heating film includes: a substrate; a heating coating, the heating coating being disposed on one surface of the substrate, the heating coating including at least one heating layer and at least one conductive layer, the heating layers and the conductive layers being alternately disposed, and the heating layer being made of a MOSH semiconductor material. Therefore, MOSH semiconductor material is a nano-scale wide bandgap semiconductor material. When the electric heating film is energized, an electric field is formed. Under the action of the electric field, the MOSH semiconductor material can release far-infrared spectral lines of a specific wavelength with good thermal effect. The conductive layer absorbs far-infrared light, and the energy of the photons is converted into heat energy, which in turn causes the conductive layer to generate heat, thereby causing the electric heating film to generate heat to heat the object to be heated. At the same time, the heating layer itself will also generate heat, effectively heating the object to be heated. Moreover, the object to be heated can also directly absorb part of the far-infrared light, and the absorbed infrared light is converted into heat and then generates heat. Moreover, the infrared spectrum heating generated by the MOSH semiconductor material can generate heat uniformly over a large area, thereby improving the heating uniformity of the electric heating film. The conductive layer has better electrical properties and thermal conductivity, so the heating coating composited with the heating layer and the conductive layer has higher electrical conductivity and stability, which can make the electric heating film heat up quickly and achieve higher electrothermal conversion efficiency, thereby improving the heating efficiency of the electric heating film.

[0006] According to an embodiment of the present invention, the heating coating layer comprises two heat-generating layers and one conductive layer.

[0007] According to an embodiment of the present invention, the heating layer satisfies at least one of the following conditions: the thickness of the heating layer is 5 to 20 nm; the MOSH semiconductor material includes one or more of CdS, MoS2, ZnS, TiO2, MoO3, SiO2, indium tin oxide, zinc aluminum oxide, and indium oxide.

[0008] According to an embodiment of the present invention, the conductive layer satisfies at least one of the following conditions: the thickness of the conductive layer is 2 to 10 nm; the material of the conductive layer includes one or more of graphene, carbon nanotubes and conductive graphite.

[0009] According to an embodiment of the present invention, the substrate satisfies at least one of the following conditions: the substrate comprises a polyester polymer material; the material of the substrate comprises one or more of polyethylene terephthalate, polybutylene terephthalate, and polyurethane; the thickness of the substrate is 5 μm-60 μm; the tensile strength of the substrate is 100 to 300 MPa; and the elongation at break of the substrate is greater than or equal to 80%.

[0010] According to an embodiment of the present invention, the electric heating film is used to heat the battery core and meets at least one of the following conditions: the electric-thermal conversion efficiency of the electric heating film is greater than or equal to 99%; the heating rate of the battery core is greater than or equal to 1.5°C / min.

[0011] In another aspect, the present invention provides a method for preparing the aforementioned electric heating film. According to an embodiment of the present invention, the method for preparing the electric heating film includes: providing a substrate; forming a heating coating on one surface of the substrate, wherein the method for preparing the heating coating includes forming at least one heating layer and at least one conductive layer, wherein the heating layer and the conductive layer are formed alternately, and the material of the heating layer includes a MOSH semiconductor material. Therefore, MOSH semiconductor material is a nano-scale wide bandgap semiconductor material. When the electric heating film is energized, an electric field is formed. Under the action of the electric field, the MOSH semiconductor material can release far-infrared spectral lines of a specific wavelength with good thermal effect. The conductive layer absorbs far-infrared light, and the energy of the photons is converted into thermal energy, which in turn causes the conductive layer to generate heat, thereby causing the electric heating film to generate heat to heat the object to be heated. At the same time, the heating layer itself will also generate heat, effectively heating the object to be heated. Moreover, the object to be heated can also directly absorb part of the far-infrared light, and the absorbed infrared light is converted into heat and then generates heat. Moreover, the infrared spectrum heating generated by the MOSH semiconductor material can generate heat uniformly over a large area, thereby improving the heating uniformity of the electric heating film. The conductive layer has better electrical properties and thermal conductivity, so the heating coating composited with the heating layer and the conductive layer has higher electrical conductivity and stability, can quickly convert electrical energy into thermal energy, thereby quickly heating the object to be heated, and can achieve higher electrothermal conversion efficiency, thereby improving the heating efficiency of the electric heating film.

[0012] According to an embodiment of the present invention, the methods of forming the heat generating layer and the conductive layer include chemical vapor deposition, physical vapor deposition or spraying.

[0013] According to an embodiment of the present invention, the heating layer is formed by magnetron sputtering, wherein the deposition power is 100-300W; and / or the conductive layer is formed by magnetron sputtering, wherein the deposition power is 100-200W.

[0014] In another aspect of the present invention, the present invention provides a battery cell. According to an embodiment of the present invention, the battery cell includes: a battery cell; the aforementioned electric heating film, the electric heating film is arranged on the surface of the battery cell, and the substrate in the electric heating film is arranged in contact with the battery cell; a first electrode and a second electrode, the first electrode and the second electrode are respectively located on both sides of the electric heating film, and are both connected to the heating coating. As a result, the electric heating film has good heating uniformity and heating rate, so it can uniformly heat the battery cell over a large area, improve the heating efficiency of the battery cell, and effectively improve the performance of the battery cell in a low temperature environment. Those skilled in the art will understand that the battery pack has all the features and advantages of the electric heating film described above, and will not be elaborated on here.

[0015] In yet another aspect, the present invention provides a battery pack. According to an embodiment of the present invention, the battery pack includes the aforementioned battery cells. As a result, the battery pack can heat up quickly and evenly in a low-temperature environment, thereby improving its battery performance in low-temperature environments.

[0016] In another aspect, the present invention provides an electrical device. According to an embodiment of the present invention, the electrical device includes the aforementioned battery pack. Thus, the electrical device still has good performance in low-temperature environments.

[0017] Additional aspects and advantages of the present invention will be set forth in part in the description which follows and, in part, will be obvious from the description which follows, or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments with reference to the accompanying drawings, in which:

[0019] Figure 1 2. It is a schematic structural diagram of an electric heating film in one embodiment of the present invention;

[0020] Figure 2 is a schematic structural diagram of an electric heating film in another embodiment of the present invention;

[0021] Figure 3 is a structural schematic diagram of a battery cell in another embodiment of the present invention;

[0022] Figure 4 is a structural schematic diagram of a battery unit in another embodiment of the present invention;

[0023] Figure 5 is a schematic diagram of a partial structure of a battery unit in another embodiment of the present invention;

[0024] Figure 6 It is a structural schematic diagram of a battery pack in another embodiment of the present invention.

[0025] Figure numerals: electric heating film 100; substrate 10; heating coating 20; heating layer 21; conductive layer 22, heating layer 21; first sublayer 11; second sublayer 12; third sublayer 13; battery unit 1000; battery core 200; first electrode 310; second electrode 320; battery pack 10000. DETAILED DESCRIPTION

[0026] Below, the scheme of the present invention will be explained in conjunction with embodiment.It will be understood by those skilled in the art that the following examples are only used to illustrate the present invention and should not be regarded as limiting the scope of the present invention.In the embodiment, if specific technology or conditions are not indicated, the technology or conditions described in the literature in this area or the product instructions are used.The reagents or instruments used are not indicated by the manufacturer, and are all conventional products that can be obtained by commercial purchase.

[0027] The present invention is described below with reference to specific examples. It should be noted that these examples are merely illustrative and do not limit the present invention in any way.

[0028] In one aspect of the present invention, the present invention provides an electric heating film. Figure 1The electric heating film 100 includes: a substrate 10; a heating coating 20, the heating coating 20 is arranged on one surface of the substrate 10, the heating coating 20 includes at least one heating layer 21 and at least one conductive layer 22, the heating layer 21 and the conductive layer 22 are arranged alternately, and the material of the heating layer 21 includes a MOSH semiconductor material. Therefore, the MOSH semiconductor material is a nano-scale wide bandgap semiconductor material. When the electric heating film is energized, an electric field is formed. Under the action of the electric field, the MOSH semiconductor material can release far-infrared spectral lines with good thermal effects of a specific wavelength. The conductive layer absorbs far-infrared light, and the energy of the photons is converted into thermal energy, thereby causing the conductive layer to generate heat, so that the electric heating film heats the object to be heated. At the same time, the heating layer itself also generates heat, effectively achieving the heating of the object to be heated. Moreover, the object to be heated can also directly absorb part of the far-infrared spectral lines, and the absorbed infrared light is converted into heat and then generates heat. Moreover, the infrared spectrum heating generated by the MOSH semiconductor material can comprehensively heat the object to be heated, can generate heat evenly over a large area, and improve the efficiency of the electric heating film. Heating uniformity; the resistivity of the conductive layer is low, and the conductive layer has better electrical properties and thermal conductivity, and can quickly establish a uniformly distributed planar electric field. Compared with the edge electric field attenuation phenomenon of the electric heating film without a conductive layer, the conductive layer in the electric heating film of the present invention can reduce the standard deviation of the electric field strength, ensuring that the MOSH semiconductor material is fully activated throughout the entire range. Moreover, the high thermal conductivity of the conductive layer can also quickly conduct heat energy laterally to the entire electric heating film layer to form a rapid heat diffusion film layer. Therefore, the heating coating composed of the heating layer and the conductive layer has higher electrical conductivity and stability, can quickly convert electrical energy into thermal energy, and then quickly heat the object to be heated, and can achieve higher electric-to-thermal conversion efficiency, thereby improving the heating efficiency of the electric heating film.

[0029] Furthermore, the 50-year power attenuation rate of MOSH semiconductor materials is less than 5%, and they can maintain stable performance under repeated hot and cold cycles. Applying the electric heating film of the present invention to batteries to heat battery cells can meet the full life cycle use requirements of vehicle batteries and help improve the service life and efficiency of batteries in low-temperature environments.

[0030] According to an embodiment of the present invention, the electric heating film 100 is used to heat the battery cell. The electric heating film 100 is placed on the outer surface of the battery cell. On the one hand, the heat generated by the electric heating film can directly heat the battery cell; on the other hand, the battery cell absorbs part of the far-infrared spectrum, which is converted into heat to heat the battery cell. Therefore, the electric heating film of the present invention can effectively heat the battery cell, allowing the battery cell to quickly return to the ambient temperature of normal operation, significantly shortening the preheating time of the battery in low-temperature environments and improving energy utilization. At the same time, the MOSH semiconductor material can achieve uniform heating inside the battery, avoiding local overheating and damage to the electrode structure.

[0031] According to some embodiments of the present invention, referring to Figure 1 The heating coating 20 comprises two heating layers 21 and a conductive layer 22, with the heating layer 21, conductive layer 22, and heating layer 21 stacked sequentially to form a sandwich structure. This heating coating structure offers high heating efficiency, high electrothermal conversion efficiency, and a stable structure. Furthermore, it is not too thick, adding no additional volume or weight to the battery, and is therefore compatible with the compact design requirements of electric vehicles.

[0032] According to some embodiments of the present invention, the thickness of the heating layer is 5 to 20 nm, such as 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, 10 nm, 11 nm, 12 nm, 13 nm, 14 nm, 15 nm, 16 nm, 17 nm, 18 nm, 19 nm, 20 nm, etc. In this way, the heating layer of the above thickness can effectively emit far-infrared spectral rays under the action of the electric field; and the thickness of the heating layer is relatively thin, which can be effectively attached to the surface of the substrate, and is convenient for integration on the surface of the object to be heated (such as the battery cell) without adding any additional volume and weight to the object to be heated; if the thickness is thin, the effect of releasing far-infrared spectral rays is relatively poor, which is not conducive to the heating effect of the electric heating film; if the thickness is thick, the cost will increase accordingly.

[0033] According to some embodiments of the present invention, the MOSH semiconductor material may be a sulfide, oxide, or other semiconductor material. In some specific embodiments, the MOSH semiconductor material includes one or more of CdS, MoS2, ZnS, TiO2, MoO3, SiO2, indium tin oxide, zinc aluminum oxide, and indium oxide. These materials can effectively emit far-infrared spectral lines of a specific wavelength with excellent thermal effects under the action of an electric field.

[0034] Furthermore, in some embodiments, when the heating coating includes multiple heating layers, the materials and thicknesses of the different heating layers can be the same or different. Those skilled in the art can flexibly adjust these materials based on actual design requirements, and this is not a limitation herein. Furthermore, the heating layers of the same layer can include a single MOSH semiconductor material or multiple different MOSH semiconductor materials.

[0035] According to some embodiments of the present invention, the thickness of the conductive layer is 2 to 10 nm, such as 2 nm, 3 nm, 4 nm, 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, 10 nm, etc. Therefore, the conductive layer of the above thickness can quickly convert light energy into heat energy after absorbing far-infrared spectral rays, and has good adhesion with the heating layer, which helps to improve the overall structural stability of the heating coating. Moreover, the thickness of the conductive layer is relatively thin, making it easy to integrate the heating coating on the surface of the object to be heated (such as a battery cell) without adding any additional volume or weight to the object to be heated.

[0036] According to some embodiments of the present invention, the conductive layer comprises one or more of graphene, carbon nanotubes, and conductive graphite. These conductive materials have good conductivity and are readily available, making them easy to prepare. Furthermore, they exhibit good stability with the heating layer material.

[0037] According to some embodiments of the present invention, the total thickness of the heating coating may be 5 to 100 nm, such as 5 nm, 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, etc. In some specific embodiments, the total thickness of the heating coating is 10 to 50 nm.

[0038] According to some embodiments of the present invention, the substrate 10 includes a polyester polymer material, which is conducive to improving the bonding force between the heating coating and the substrate. In some specific embodiments, the material of the substrate 10 includes one or more of polyethylene terephthalate (PET), polybutylene terephthalate (PBT), and polyurethane (PU). As a result, the above-mentioned material has good thermal conductivity and can transfer the heat generated by the heating coating to the object to be heated, thereby ensuring a better heating efficiency of the object to be heated; moreover, the surface of the substrate of the above-mentioned material can have good surface hydrophilicity and adhesion after treatment, thereby improving the adhesion of the heating coating on the surface of the substrate and improving the overall structural stability of the electric heating film; at the same time, the substrate provides a good support for the heating coating, which facilitates the integration of the electric heating film into the surface of the object to be heated.

[0039] In some embodiments, the substrate can be a single-layer structure. In the single-layer structure, the following two situations can be included: first, the substrate is a single-layer structure of a single material, such as a PET layer, a PBT layer or a PU layer; second, the substrate is a single-layer structure including multiple materials, that is, a single-layer structure substrate is prepared by mixing two different raw materials, such as a single-layer structure substrate including two or three raw materials of PET, PBT and PU.

[0040] In other embodiments, the substrate 10 is a composite layer of a multi-layer structure, and the multi-layer structure substrate can be stacked by at least two or three layers of PET layers, PBT layers and PU layers, and the materials of different sub-layers can be the same or different. For example, the substrate 10 is a composite layer including a PET layer and a PBT layer, and the number of layers can be two, three or more layers; or the substrate 10 is a composite layer including a PET layer and a PU layer, and the number of layers can be two, three or more layers; or the substrate 10 is a composite layer including a PBT layer and a PU layer, and the number of layers can be two, three or more layers; or the substrate 10 is a composite layer including a PET layer, a PBT layer and a PU layer, and the number of layers can be two, three or more layers. Among them, in the composite layer structure, there is no requirement for the stacking order of the multiple sub-layers, and those skilled in the art can flexibly set it according to actual needs. In some specific embodiments, such as Figure 2 As shown, the substrate 10 includes a first sub-layer 11 , a second sub-layer 12 and a third sub-layer 13 .

[0041] According to some embodiments of the present invention, the thickness of the substrate is 5 μm-60 μm, such as 5 μm, 8 μm, 10 μm, 12 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm, 60 μm, etc. The substrate of the above thickness has good support and toughness, allowing the electric heating film to be well adhered to the surface of the object to be heated (such as a battery cell).

[0042] According to some embodiments of the present invention, the tensile strength of the substrate is 100-300 MPa, such as 100 MPa, 120 MPa, 150 MPa, 180 MPa, 200 MPa, 220 MPa, 250 MPa, 280 MPa, 300 MPa, etc.; the elongation at break of the substrate is greater than or equal to 80%, such as 80%, 82%, 85%, 87%, 88%, 90%, 92%, 94%, 95%, 97%, 99%, etc. A substrate with the above-mentioned mechanical properties can have a better load-bearing capacity when the heating coating is prepared by deposition or spraying processes; and it can be well adhered to non-planar surfaces to be heated, thereby expanding the application environment of the electric heating film.

[0043] According to an embodiment of the present invention, the electric heating film has an electric-to-heat conversion efficiency greater than or equal to 99%, and the heating rate of the battery core is greater than or equal to 1.5°C / min. This shows that the electric heating film of the present invention has a good heating rate and energy conversion efficiency, and can significantly heat the object to be heated in a short time.

[0044] In another aspect of the present invention, the present invention provides a method for preparing the aforementioned electric heating film. According to an embodiment of the present invention, the method for preparing the electric heating film comprises:

[0045] S100: providing a substrate.

[0046] In some embodiments, the substrate may be cleaned and pretreated. In some specific embodiments, the substrate is sequentially immersed in a cleaning agent such as acetone, ethanol, and deionized water and ultrasonically cleaned to remove surface organic matter and particles. The substrate is then dried with nitrogen and placed in a drying oven. Finally, the substrate surface is treated with oxygen plasma to improve its hydrophilicity and adhesion.

[0047] During cleaning, the cleaning agent temperature can be 30-60°C. Lower temperatures may result in poor cleaning results; higher temperatures may adversely affect the substrate. The cleaning time for different cleaning agents ranges from 3 to 10 minutes to effectively remove organic matter and particles from the substrate surface. Furthermore, the acetone cleaning conditions include: ultrasonic cleaning at 50°C for 5 minutes to remove surface grease; ethanol rinsing: using a 95% ethanol solution to remove residual acetone to prevent solvent residue from affecting coating adhesion; and deionized water rinsing: using ultrapure water with a resistivity of >18MΩ·cm to ensure that the surface is free of particle contamination.

[0048] In some embodiments, the drying temperature may be 50-80° C., and the drying time may be 0.5-2 hours. Within the above temperature and time ranges, the substrate can be dried quickly without causing adverse deformation of the substrate and increasing energy consumption.

[0049] In some embodiments, the oxygen plasma treatment power is 50-200W for 1-5 minutes. Under these conditions, the hydrophilicity and adhesion of the substrate surface can be significantly improved. If the power is too low, the improvement in surface hydrophilicity and adhesion is insignificant. If the power is too high, the substrate surface may be damaged. If the treatment time is too long, the substrate surface may be over-etched. If the treatment time is too short, the treatment is insufficient, and the substrate surface improvement is insignificant.

[0050] S200: forming a heating coating on one surface of the substrate, wherein the method for preparing the heating coating comprises forming at least one heating layer and at least one conductive layer, wherein the heating layer and the conductive layer are alternately formed, and the material of the heating layer comprises a MOSH semiconductor material.

[0051] According to some embodiments of the present invention, the methods for forming the heating layer and the conductive layer include chemical vapor deposition, physical vapor deposition (such as magnetron sputtering), or spraying, respectively. Thus, the above methods can well control the thickness of the heating layer and the conductive layer, and ensure that the heating coating has good adhesion to the substrate surface.

[0052] According to some embodiments of the present invention, magnetron sputtering can be used to deposit the various heating layers and conductive layers in the heating coating. The film formed by this method has the advantages of uniform film formation, good density, and strong adhesion. Moreover, the thickness and composition of the film can be precisely controlled to ensure the quality and performance stability of the heating coating. Moreover, during the plasma treatment process of magnetron sputtering, polar groups such as -OH and -COOH are formed through oxidation of oxygen free radicals, which strengthens the chemical bonding between the film layer and the substrate, and between the film layers. This makes it less likely for the film layer to fall off during long-term use, thereby improving the reliability and service life of the electric heating film.

[0053] According to some embodiments of the present invention, a heating layer is formed by magnetron sputtering, wherein the deposition power is 100 to 300 W, such as 100 W, 150 W, 200 W, 250 W, 300 W, etc. Under the above conditions, a heating layer of relatively good quality can be efficiently deposited; if the power is low, the deposition rate is slow; if the power is high, the deposited heating layer may have relatively more defects, affecting its function. Furthermore, in some specific embodiments, in the magnetron sputtering process, the time for pre-sputtering to clean the target surface is 3-10 minutes. If the time is too short, the cleaning of the target surface is relatively incomplete; if the time is too long, time and resources are wasted.

[0054] According to some embodiments of the present invention, a conductive layer is formed by magnetron sputtering, wherein the deposition power is 100 to 200 W, such as 100 W, 120 W, 150 W, 180 W, 200 W, etc. Under the above conditions, a conductive layer of relatively good quality can be efficiently deposited; if the power is too low, the deposition rate is too slow; if the power is too high, the deposited conductive layer may have relatively more defects, affecting its function. Furthermore, in some specific embodiments, in the magnetron sputtering process, the time for pre-sputtering to clean the target surface is 2-5 minutes, which can better remove the contaminants on the target surface. If the time is too short, the target surface cleaning is relatively incomplete; if the time is too long, time and resources are wasted.

[0055] According to an embodiment of the present invention, in the above-mentioned preparation method, MOSH semiconductor material is used as a nanoscale wide bandgap semiconductor material. When the electric heating film is energized, an electric field is formed. Under the action of the electric field, the MOSH semiconductor material can release far-infrared spectral lines of a specific wavelength with good thermal effect. The conductive layer absorbs far-infrared light, and the energy of the photons is converted into thermal energy, thereby causing the conductive layer to generate heat, thereby causing the electric heating film to generate heat to heat the object to be heated. Moreover, the object to be heated can also directly absorb part of the far-infrared light, and the absorbed infrared light is converted into heat and then generates heat; moreover, the infrared spectrum heating generated by the MOSH semiconductor material can generate heat uniformly over a large area, thereby improving the heating uniformity of the electric heating film; the conductive layer has better electrical properties and thermal conductivity, so the heating coating compositely arranged with the heating layer and the conductive layer has higher electrical conductivity and stability, which can make the electric heating film heat up quickly, and can achieve higher electrothermal conversion efficiency, thereby improving the heating efficiency of the electric heating film.

[0056] In another aspect of the present invention, the present invention provides a battery cell. Figure 3 、 Figure 4 and Figure 5 , the battery unit 1000 includes: a battery cell 200; the aforementioned electric heating film 100, the electric heating film 100 is arranged on the surface of the battery cell 200, and the substrate in the electric heating film 100 is arranged in contact with the battery cell 200; a first electrode 310 and a second electrode 320, the first electrode 310 and the second electrode 320 are respectively located on both sides of the electric heating film 100, and are both connected to the heating coating 20. The first electrode and the second electrode are connected to the external power supply to provide current, thereby heating the battery cell and improving the low-temperature performance of the battery cell. Among them, the electric heating film has good heating uniformity and heating rate, so it can evenly heat the battery cell over a large area, improve the heating efficiency of the battery cell, and effectively improve the performance of the battery cell in a low-temperature environment. Those skilled in the art will understand that the battery pack has all the features and advantages of the electric heating film described above, and will not be elaborated on here.

[0057] According to some embodiments of the present invention, the electric heating film 100 may cover a portion of the outer surface of the battery cell 200 , or may cover the entire outer surface of the battery cell 200 .

[0058] According to some embodiments of the present invention, there are no special requirements for the specific shape of the battery cell, and the battery cell may be a battery cell with a laminated structure or a battery cell with a wound structure.

[0059] Furthermore, there are no special requirements for the specific size of the battery cell, and those skilled in the art can flexibly select according to actual needs. In some specific embodiments, the size (length * width * thickness) of a single laminated battery cell is 1000mm * 100mm * 18mm.

[0060] According to some embodiments of the present invention, the materials of the first electrode and the second electrode can be at least one of aluminum, copper, nickel, tungsten, silver, iron, chromium, zinc, and silver, respectively. The first electrode and the second electrode can be the same or different.

[0061] Furthermore, there are no specific requirements for the dimensions of the first and second electrodes, and those skilled in the art may flexibly select the dimensions based on actual needs. In some specific embodiments, the first and second electrodes may be metal strips with dimensions (length * width * thickness) of 240 mm * 20 mm * 6 μm.

[0062] According to some embodiments of the present invention, there are no special requirements for the specific type of battery cell, and those skilled in the art can flexibly select the type based on actual needs. In some embodiments, the battery cell can be a lithium-ion battery cell, a sodium-ion battery cell, a lead-acid battery cell, a nickel-cadmium battery cell, a nickel-metal hydride battery cell, a lithium polymer battery cell, or other battery cell types.

[0063] In another aspect, the present invention provides a battery pack. According to an embodiment of the present invention, the battery pack 10000 includes the aforementioned battery cell 1000. As a result, the battery pack can heat up quickly and evenly in a low-temperature environment, thereby improving its battery performance in low-temperature environments.

[0064] According to some embodiments of the present invention, the battery pack further includes an external power source. The first and second electrodes of the multiple battery cells 1000 in the battery pack are connected to the external power source so that the external power source can supply power and heat the heating coatings in the battery cells. The electric heating coatings in different battery cells can be connected in parallel or in series. The external power source can be a battery.

[0065] According to some embodiments of the present invention, when the temperature of the battery pack environment is low, such as below 0°C, -5°C, -10°C, -15°C, or -20°C, an external power source is connected via a switch to begin heating the battery cells in the battery unit, raising the internal temperature of the cells to prevent charging and discharging at a lower temperature, which could affect battery performance such as the battery cycle. When the cells are heated to a predetermined temperature, the circuit is disconnected, power is stopped, and heating of the cells is stopped to prevent the cells from overheating. The predetermined temperature may be between 20°C and 40°C.

[0066] In another aspect, the present invention provides an electrical device. According to an embodiment of the present invention, the electrical device includes the aforementioned battery pack. Thus, the electrical device still has good performance in low-temperature environments.

[0067] According to an embodiment of the present invention, the electrical device may be a vehicle.

[0068] Example

[0069] Example 1

[0070] Provide PET substrate: thickness of 20μm, tensile strength up to 180MPa, elongation at break ≥100%.

[0071] Pretreatment of the PET substrate: Immerse the substrate in acetone and ultrasonically clean it at 50°C for 5 minutes to remove surface grease. Then, rinse the substrate in 95% ethanol to remove any residual acetone. Finally, ultrasonically clean the substrate in deionized water with a resistivity greater than 18 MΩ·cm. Dry the cleaned substrate in a drying oven at 60°C for 1 hour before treating with 100W of oxygen plasma.

[0072] Magnetron sputtering deposition of TiO2 heating layer: fix the PET substrate on the substrate stage of the sputtering chamber, and evacuate the sputtering chamber to a vacuum of ≤5×10 -4 Pa, open the titanium target (99.99%), introduce argon, pre-sputter clean the target surface, control the TiO2 sputtered film thickness to 10nm, wherein the deposition power is 200W, the pre-sputtering time is 5 minutes.

[0073] Magnetron sputtering deposition of a graphene conductive layer: The titanium target was switched off and replaced with a graphene target. After pre-sputtering, the sputtering time and graphene layer thickness were controlled to 5 nm. The deposition power was 150 W, and the pre-sputtering time was 3 minutes.

[0074] The TiO2 heating layer was deposited again by magnetron sputtering: the titanium target was switched on, argon gas was introduced, and the target surface was pre-sputtered to clean it. The thickness of the TiO2 sputtered film was controlled to 10nm. The deposition power was 200W, and the pre-sputtering time was 5 minutes. This resulted in the production of an electric heating film.

[0075] The prepared electric heating film is covered on the surface of a single laminated lithium-ion battery cell (size 1000mm*100mm*18mm), and copper strips (size 240mm*20mm*6μm) are added near the tabs at both ends of the cell as the first electrode and the second electrode, and finally assembled into a battery pack.

[0076] Example 2

[0077] The preparation method is basically the same as that of Example 1, except that the substrate is a PU substrate, the acetone cleaning temperature is 40° C., and the power of the oxygen plasma treatment is 90 W.

[0078] Example 3

[0079] The preparation method is basically the same as that of Example 1, except that the heating coating includes MoS2 / graphene / MoS2 deposited in sequence.

[0080] Example 4

[0081] The preparation method is basically the same as that in Example 1, with the following differences: the substrate is a composite layer of a multilayer structure of PET layer / PU layer / PET layer, the tensile strength of the substrate is 220 MPa, the elongation at break is ≥90%, and the thicknesses are 10 μm, 5 μm, and 10 μm, respectively; the heating coating includes a MoS2 heating layer, a graphene conductive layer, and a MoS2 heating layer deposited sequentially.

[0082] Example 5

[0083] The preparation method is basically the same as that in Example 1, with the following differences: the substrate is a single-layer structure made by mixing raw materials PET and PU in a 1:1 ratio by mass, the tensile strength can reach 200 MPa, the elongation at break is ≥80%, the acetone cleaning temperature is 45°C, and the drying temperature is 80°C; the heating coating includes a MoS2 heating layer, a graphene conductive layer, and a MoS2 heating layer deposited in sequence.

[0084] Example 6

[0085] The preparation method is basically the same as that of Example 5, except that the acetone cleaning temperature is 50° C., the drying temperature is 70° C., and the power of the oxygen plasma treatment is 90 W.

[0086] Example 7

[0087] The preparation method is basically the same as that in Example 1, with the following differences: the substrate thickness is 30 μm, the acetone cleaning time is 8 minutes, and the drying temperature is 75°C; the deposition time of the heating layer is 4 minutes, and the thicknesses of the TiO2 heating layer, graphene conductive layer, and TiO2 heating layer in the heating coating are 8 nm, 5 nm, and 8 nm, respectively.

[0088] Example 8

[0089] The preparation method is basically the same as that of Example 7, with the following differences: the deposition power of the heating layer is 250W, and the time is 5 minutes; the deposition power of the heating layer is 160W, and the time is 4 minutes; the thicknesses of the TiO2 heating layer, graphene conductive layer, and TiO2 heating layer in the heating coating are 12nm, 8nm, and 12nm, respectively.

[0090] Example 9

[0091] The preparation method is basically the same as that of Example 1, except that the heating coating includes a double-layer structure of a TiO2 heating layer and a graphene conductive layer, and the TiO2 heating layer is arranged in contact with the substrate, that is, the step of magnetron sputtering deposition of the TiO2 heating layer again is not included.

[0092] Comparative Example 1

[0093] In the battery pack, a resistance wire is installed on the outer surface of a battery cell with the same structure and size as in Example 1. When current flows through the resistance wire, it generates heat, which heats the battery case in contact with it. The number of battery cells in the battery pack is the same.

[0094] Comparative Example 2

[0095] The battery pack uses a liquid heating system to heat the cells. This system involves placing a container containing thermal oil on the surface of the cell. When heating the battery, the liquid in the container is heated, and then the heat is transferred from the container in contact with the cell to the cell, raising the temperature. The cells have the same structure and dimensions as those in Example 1, and the battery pack contains the same number of battery cells.

[0096] Comparative Example 3

[0097] The preparation method comprises:

[0098] Provide PET substrate: thickness of 20μm, tensile strength up to 180MPa, elongation at break ≥100%.

[0099] Pretreatment of the PET substrate: Immerse the substrate in acetone and ultrasonically clean it at 50°C for 5 minutes to remove surface grease. Then, rinse the substrate in 95% ethanol to remove any residual acetone. Finally, ultrasonically clean the substrate in deionized water with a resistivity greater than 18 MΩ·cm. Dry the cleaned substrate in a drying oven at 60°C for 1 hour before treating with 100W of oxygen plasma.

[0100] Magnetron sputtering deposition of TiO2 heating layer: fix the PET substrate on the substrate stage of the sputtering chamber, and evacuate the sputtering chamber to a vacuum of ≤5×10 -4 Pa, open the titanium target (99.99%), introduce argon, pre-sputter clean the target surface, control the TiO2 sputtered film thickness to 20nm. Among them, the deposition power is 200W, and the pre-sputtering time is 5 minutes.

[0101] The prepared electric heating film is covered on the surface of a single laminated lithium-ion battery cell (size 1000mm*100mm*18mm), and copper strips (size 240mm*20mm*6μm) are added near the tabs at both ends of the cell as the first electrode and the second electrode, and finally assembled into a battery pack.

[0102] The electric heating film, resistance wire, and liquid heating system in the battery packs of the above embodiments and comparative examples were connected to the same external power supply, and the heating rate of the battery cell and the photoelectric conversion efficiency of the electric heating film were tested. The heating and temperature test methods in GB / T31485-2015 (Safety requirements and test methods for power batteries for electric vehicles) and ISO 6469-1 (Electric vehicle safety specification - thermal management part) were used to test the termination temperature of the battery cell heating, and the heating rate and energy conversion efficiency were calculated. The heating rate = (heating termination temperature - initial temperature) / heating time, energy conversion efficiency: power consumption = voltage × current × power-on time, battery heating absorption heat = battery specific heat capacity × temperature rise, energy conversion efficiency = battery heating absorption heat / power consumption. The above battery pack was placed at -20°C, started to connect the external power supply, and heated the battery cell. Heating was stopped after the surface temperature of the battery cell shell reached 35°C. The test results of the battery cell heating rate and the photoelectric conversion efficiency of the electric heating film during this process are shown in Table 1.

[0103] Table 1

[0104]

[0105]

[0106] It can be seen from the data in Table 1 that compared with the heating method in the comparative example, the electric heating film of the present invention can heat the battery core quickly and stably, and has a higher energy conversion efficiency, and has better heating uniformity, and there will be no local temperature being too high or too low. By comparison, it can be seen that various settings of the substrate can achieve uniform, fast and effective heating of the battery core, and different MOSH semiconductor materials can effectively achieve fast, uniform and effective heating of the battery core; by comparing Examples 1 and 3, it can be seen that the heating layers of different materials will cause the electric heating film to have different heating efficiencies, but the electric heating film has good heating efficiency, that is, the electrothermal conversion efficiency is greater than or equal to 99%, and the heating rate of the battery core is greater than 1.5°C / min.

[0107] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature specified as "first" or "second" may explicitly or implicitly include one or more of the features. Throughout the description of this application, "plurality" means two or more, unless otherwise specifically defined.

[0108] In the description of this specification, the reference terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and features of different embodiments or examples without contradiction.

[0109] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. An electric heating film, characterized in that: include: substrate; A heating coating is provided on one surface of the substrate, the heating coating comprises at least one heating layer and at least one conductive layer, the heating layer and the conductive layer are alternately provided, and the material of the heating layer comprises a MOSH semiconductor material.

2. The electric heating film according to claim 1, characterized in that: The heating coating layer comprises two heat-generating layers and one conductive layer.

3. The electric heating film according to claim 1 or 2, characterized in that: The heating layer satisfies at least one of the following conditions: The thickness of the heating layer is 5 to 20 nm; The MOSH semiconductor material includes one or more of CdS, MoS2, ZnS, TiO2, MoO3, SiO2, indium tin oxide, zinc aluminum oxide, and indium oxide.

4. The electric heating film according to claim 1 or 2, characterized in that: The conductive layer satisfies at least one of the following conditions: The thickness of the conductive layer is 2 to 10 nm; The material of the conductive layer includes one or more of graphene, carbon nanotubes and conductive graphite.

5. The electric heating film according to claim 1 or 2, characterized in that: The substrate satisfies at least one of the following conditions: The substrate comprises a polyester polymer material; The material of the substrate includes one or more of polyethylene terephthalate, polybutylene terephthalate, and polyurethane; The thickness of the substrate is 5 μm-60 μm; The tensile strength of the substrate is 100 to 300 MPa; The elongation at break of the substrate is greater than or equal to 80%.

6. The electric heating film according to claim 1 or 2, characterized in that: The electric heating film is used to heat the battery core and meets at least one of the following conditions: The electric heating film has an electric-to-heat conversion efficiency greater than or equal to 99%; The heating rate of the battery cell is greater than or equal to 1.5°C / min.

7. A method for preparing the electric heating film according to any one of claims 1 to 6, characterized in that: include: providing a substrate; A heating coating is formed on one surface of the substrate. The method for preparing the heating coating includes forming at least one heating layer and at least one conductive layer, and the heating layer and the conductive layer are formed alternately. The material of the heating layer includes MOSH semiconductor material.

8. The method according to claim 7, characterized in that Methods of forming the heat generating layer and the conductive layer include chemical vapor deposition, physical vapor deposition, or spraying, respectively.

9. The method according to claim 8, characterized in that The heating layer is formed by magnetron sputtering, wherein the deposition power is 100 to 300 W; And / or, the conductive layer is formed by magnetron sputtering, wherein the deposition power is 100-200W.

10. A battery cell, characterized in that: include: battery cells; The electric heating film according to any one of claims 1 to 6, wherein the electric heating film is arranged on the surface of the battery core, and the substrate in the electric heating film is arranged in contact with the battery core; The first electrode and the second electrode are respectively located on both sides of the electric heating film and are both connected to the heating coating.

11. A battery pack, characterized in that: Comprising the battery cell according to claim 10.

12. An electrical device, characterized in that: Including the battery pack according to claim 11.

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