Battery cell, battery apparatus and electric device

Abstract

The present application relates to the technical field of battery production, and provides a battery cell, a battery apparatus, and an electric device. The battery cell comprises a casing, a top cover, an electrode assembly, an insulating member, and a thermally conductive coating, wherein the casing is provided with an accommodating cavity and an open end; the top cover covers the open end of the casing; the electrode assembly is arranged in the accommodating cavity; the electrode assembly comprises a top end portion facing the top cover and a bottom end portion opposite to the top end portion; the insulating member is arranged between the top cover and the top end portion; and at least part of the insulating member and / or at least part of the top end portion is coated with the thermally conductive coating. In the battery cell provided by the present application, the thermally conductive coating is added, and the thermally conductive coating is arranged on the insulating member and / or the top end portion of the electrode assembly, so as to increase the heat transfer rate between the top end portion of the electrode assembly and the outside, thereby improving the heat exchange efficiency at the top of the battery cell, reducing the heat exchange difference between the top and bottom of the battery cell, and improving the performance of the battery cell to a certain extent.

Description

Battery cells, battery devices and electrical equipment

[0001] This application incorporates, in its entirety, national patent application No. 202411918143.0 entitled “Battery Cell, Battery Device and Electrical Equipment”, filed on December 24, 2024, which is incorporated herein by reference. Technical Field

[0002] This application relates to the field of battery manufacturing technology, and in particular to a battery cell, battery device and electrical equipment. Background Technology

[0003] After the battery cells are assembled into modules, the bottom of the battery cell module is usually cooled by a water cooling system. However, the top of the battery cell lacks direct and effective heat exchange measures, which often results in the temperature rise at the top of the battery module being significantly higher than that at the bottom, ultimately affecting the performance of the battery device. Technical issues

[0004] The purpose of this application is to provide a battery cell, a battery device, and an electrical appliance, which aims to solve the technical problem of performance degradation caused by the large heat exchange difference between the top and bottom of the battery cell. Technical solutions

[0005] To solve the above-mentioned technical problems, the technical solution adopted in the embodiments of this application is as follows:

[0006] In a first aspect, this application provides a battery cell, comprising:

[0007] The housing has a receiving cavity and an open end.

[0008] A top cover, which is disposed over the opening end of the housing;

[0009] An electrode assembly having a top end portion disposed toward the top cover and a bottom end portion disposed opposite to the top end portion;

[0010] An insulating element disposed between the top cover and the top end portion; and,

[0011] A thermally conductive coating is applied to at least a portion of the insulating element and / or at least a portion of the top portion.

[0012] The beneficial effects of this utility model are as follows: The battery cell provided by this utility model is provided with a thermally conductive coating, and the thermally conductive coating is provided on the top part of the insulating part and / or the electrode assembly to increase the heat transfer rate between the top part of the electrode assembly and the outside world, thereby improving the heat exchange efficiency of the top of the battery cell, reducing the heat exchange difference between the top and bottom of the battery cell, and improving the performance of the battery cell to a certain extent.

[0013] In one embodiment, the electrode assembly includes a positive electrode, a separator, and a negative electrode. The positive electrode, the separator, and the negative electrode are sequentially wound or stacked. The negative electrode includes a main body portion corresponding to the positive electrode and a protrusion portion extending beyond the positive electrode in the width direction of the main body portion. The area of ​​the protrusion portion covered by the separator is coated with the thermally conductive coating.

[0014] By adopting the above technical solution, the protruding part of the negative electrode sheet should be the part that first contacts the electrode assembly and the insulating component. Therefore, applying a thermally conductive coating to the separator area covering the protruding part can improve the heat exchange efficiency between the electrode assembly and the insulating component, thereby improving the heat exchange efficiency between the top of the battery cell and the outside.

[0015] In one embodiment, the insulating element has a bottom surface facing the electrode assembly and a top surface facing the top cover, the top surface and / or the bottom surface being coated with the thermally conductive coating.

[0016] By adopting the above technical solution, a thermally conductive coating is applied to the top and / or bottom surface of the insulating component to improve its heat exchange capacity.

[0017] In one embodiment, the thermally conductive coating comprises an insulating substrate and thermally conductive fillers dispersed within the insulating substrate, wherein the thermally conductive fillers account for 5% to 60% of the total mass of the thermally conductive coating; or...

[0018] The thermal conductivity of the thermally conductive coating is ≥2W / (m·K).

[0019] By adopting the above technical solution, the thermally conductive coating mainly consists of thermally conductive filler and an insulating substrate. The insulating substrate serves a load-bearing function, while the thermally conductive filler provides high thermal conductivity. Furthermore, the mass ratio of the two components is adjusted according to actual application requirements.

[0020] In one embodiment, the thermally conductive filler comprises any one or both of boron nitride and aluminum nitride, wherein the thermal conductivity of the thermally conductive filler is ≥80 W / (m·K); or,

[0021] The insulating matrix includes any one or more of polyimide, polyamide, and epoxy resin, wherein the molecular weight of the insulating matrix is ​​8*10. 4 ~40*10 4 .

[0022] By adopting the above technical solution, appropriate thermally conductive fillers and insulating substrates can be selected according to actual usage requirements. For example, the thermally conductive filler can be any one or two of boron nitride and aluminum nitride, and the insulating substrate can be any one or several of polyimide, polyamide, and epoxy resin.

[0023] In one embodiment, the method for preparing the thermally conductive coating includes the following steps;

[0024] The thermally conductive filler is dispersed in a solvent to form a filler suspension, and the insulating matrix is ​​dispersed in the same solvent to form a polymer solution. Finally, the filler suspension and the polymer solution are mixed to form a mixture solution.

[0025] The mixture solution is coated and, after curing, forms a thermally conductive coating, wherein the curing temperature of the mixture solution is 80℃~140℃.

[0026] By adopting the above technical solution, a filler suspension and a polymer solution are first obtained, and then the two are mixed to form a mixture solution. Finally, a thermally conductive coating is formed by curing.

[0027] In one embodiment, the thickness μ of the thermally conductive coating is (0.02~0.08) * the capacity of the battery cell.

[0028] By adopting the above technical solution, in order to reduce the impact of the thickness of the thermal conductive coating on the capacity of the battery cell, it is necessary to control the thickness of the thermal conductive coating while ensuring a certain heat exchange efficiency.

[0029] In one embodiment, the thickness μ of the thermally conductive coating is (0.033~0.066) * the capacity of the battery cell.

[0030] By adopting the above technical solution and controlling the thickness of the thermally conductive coating within the aforementioned range, the heat exchange efficiency at the top of the battery cell can be improved while achieving a larger capacity for the battery cell.

[0031] Secondly, this application provides a battery device including the battery cell described above.

[0032] Thirdly, this application provides an electrical device including a battery device as described in any of the above, the battery device being used to store or provide electrical energy.

[0033] It is understood that the beneficial effects of the second and third aspects mentioned above can be found in the relevant descriptions in the first aspect mentioned above, and will not be repeated here.

[0034] The above description is only an overview of the technical solution of this application. In order to better understand the technical means of this application and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of this application more obvious and understandable, the following are specific embodiments of this application. Attached Figure Description

[0035] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or exemplary technologies will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0036] Figure 1 is a structural schematic diagram of the vehicle provided in an embodiment of this application;

[0037] Figure 2 is a schematic diagram of the battery device provided in an embodiment of this application;

[0038] Figure 3 is an exploded view of a single battery cell provided in an embodiment of this application;

[0039] Figure 4 is a cross-sectional view of the electrode assembly of a battery cell provided in an embodiment of this application;

[0040] Figure 5 is a front view of the negative electrode contact of the battery cell provided in the embodiment of this application, which is covered with a separator;

[0041] Figure 6 is a cross-sectional view of the thermally conductive coating of the battery cell provided in the embodiment of this application;

[0042] Figure 7 is a flowchart of the method for preparing the thermally conductive coating of the battery cell provided in the embodiments of this application.

[0043] Explanation of reference numerals in the attached drawings: 1000, vehicle; 100, battery device; 200, controller; 300, motor; 10, battery cell; 11, electrode assembly; 12, housing; 13, top cover; 11a, top end; 11b, bottom end; 14, insulating component; 15, thermally conductive coating; 111, positive electrode; 112, separator; 113, negative electrode; 1131, main body; 1132, protrusion; 14a, top surface; 14b, bottom surface; 151, insulating substrate; 152, thermally conductive filler; 20, housing; 21, first part; 22, second part. Embodiments of the present invention

[0044] The embodiments of the technical solution of this application will now be described in detail with reference to the accompanying drawings. These embodiments are only used to more clearly illustrate the technical solution of this application and are therefore merely examples, and should not be used to limit the scope of protection of this application.

[0045] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0046] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0047] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0048] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0049] In the description of the embodiments of this application, the term "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces).

[0050] In the description of the embodiments of this application, the technical terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this application and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application.

[0051] In the description of the embodiments of this application, unless otherwise expressly specified and limited, technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0052] A battery device may include one or more individual battery cells for providing voltage and capacity. Multiple battery cells form a battery cell assembly, and multiple battery cells are connected in series, parallel, or mixed connections via a busbar.

[0053] The battery device can be a battery pack, which generally includes a housing and one or more individual battery cells housed in the housing.

[0054] A battery cell typically includes a positive electrode, a negative electrode, a separator, and a casing. The positive electrode, negative electrode, and separator are assembled into an electrode assembly by winding or stacking. The electrode assembly is then placed inside the casing and injected with electrolyte to form a battery cell.

[0055] In related technical fields, after battery cells are assembled into modules, the bottom of the battery cell assembly is usually cooled by a water cooling system for heat exchange, while the top of the battery cell lacks corresponding water cooling heat exchange, resulting in a large temperature difference between the top and bottom of the battery cell, which ultimately affects the performance of the battery cell.

[0056] In view of this, this application provides a battery cell with an added thermally conductive coating, and the thermally conductive coating is applied to the low thermal conductivity region at the top of the battery cell. Specifically, the thermally conductive coating is applied to at least a portion of the insulating component and / or at least a portion of the top portion to increase the heat transfer rate between the top portion of the electrode assembly and the outside environment, thereby improving the heat exchange efficiency at the top of the battery cell, reducing the heat exchange difference between the top and bottom of the battery cell, and improving the performance of the battery cell to a certain extent.

[0057] Referring to Figure 2, this application embodiment also provides a battery device 100, which includes one or more battery cell components. The battery device 100 disclosed in this application embodiment can be used in electrical devices that use the battery device 100 as a power source or in various energy storage devices and systems that use the battery device 100 as an energy storage element. Electrical devices can be, but are not limited to, mobile phones, portable devices, laptops, electric toys, power tools, electric vehicles, vehicles, ships, spacecraft, etc. Electric toys can include stationary or mobile electric toys, such as game consoles, electric car toys, electric boat toys, and electric airplane toys, etc. Spacecraft can include airplanes, rockets, space shuttles, and spacecraft, etc.

[0058] For ease of explanation, the following embodiments will be described using a vehicle 1000 as an example of an electrical device according to an embodiment of this application.

[0059] Please refer to Figure 1, which is a structural schematic diagram of a vehicle 1000 provided in some embodiments of this application. The vehicle 1000 can be a gasoline-powered vehicle, a natural gas-powered vehicle, or a new energy vehicle. New energy vehicles can be pure electric vehicles, hybrid electric vehicles, or range-extended electric vehicles, etc. A battery device 100 is installed inside the vehicle 1000, and the battery device 100 can be located at the bottom, front, or rear of the vehicle 1000. The battery device 100 can be used to power the vehicle 1000; for example, the battery device 100 can serve as the operating power source for the vehicle 1000. The vehicle 1000 may also include a controller 200 and a motor 300. The controller 200 is used to control the battery device 100 to supply power to the motor 300, for example, to meet the power needs of the vehicle 1000 during startup, navigation, and driving.

[0060] In some embodiments of this application, the battery device 100 can not only serve as the operating power source for the vehicle 1000, but also as the driving power source for the vehicle 1000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 1000.

[0061] According to some embodiments of this application, please refer to Figures 3 to 6. This application provides a battery cell 10, including a housing 12, a top cover 13, an electrode assembly 11, an insulating component 14, and a thermally conductive coating 15.

[0062] The housing 12 has a receiving cavity and an open end, and a top cover 13 is disposed on the open end of the housing 12; an electrode assembly 11 is placed in the receiving cavity, and the electrode assembly 11 has a top end portion 11a disposed toward the top cover 13 and a bottom end portion 11b disposed opposite to the top end portion 11a; an insulating member 14 is disposed between the top cover 13 and the top end portion 11a; and a thermally conductive coating 15 is coated on at least a portion of the insulating member 14 and / or at least a portion of the top end portion 11a.

[0063] Understandably, the housing 12 should have a receiving cavity and also an open end for the power supply assembly to enter the receiving cavity. The top cover 13 is placed over the open end of the housing 12, serving a corresponding sealing function and a current outflow function.

[0064] The electrode assembly 11 should include an electrode body and a tab. In its normal placement state, the end of the electrode assembly 11 with the tab can be the top part 11a, which corresponds to the top cover 13, and the end of the electrode assembly 11 without the tab is the bottom part 11b, which is away from the opening end of the housing 12, that is, away from the top cover 13.

[0065] The insulating member 14 provides insulation for the top cover 13, thereby reducing the probability that the tabs of the electrode assembly 11 will come into direct contact with the top cover 13. Therefore, the insulating member 14 is disposed between the top cover 13 and the top end 11a of the electrode assembly 11.

[0066] The thermally conductive coating 15 is a coating with insulation and high thermal conductivity. For example, the thermally conductive coating 15 may consist of two parts: high thermal conductivity particles and an organic matrix. The high thermal conductivity particles are evenly dispersed in the organic matrix and then applied to the insulating component 14 or the top end 11a of the electrode assembly 11 by means of spraying, bonding or other connection methods.

[0067] Here, the thermally conductive coating 15 can completely cover the surface of the insulating member 14, or it can partially cover the surface of the insulating member 14. For example, the insulating member 14 has a first surface facing the top cover 13 and a second surface facing the top end 11a of the electrode assembly 11. According to actual usage requirements, the thermally conductive coating 15 can be coated on the first surface and / or the second surface to form a partial coverage of the insulating member 14. Of course, the insulating member 14 also has a side wall surface connecting the first surface and the second surface. In order to improve the thermal conductivity of the insulating member 14, the thermally conductive coating 15 can also be coated on the side wall surface to achieve complete coverage of the surface of the insulating member 14 by the thermally conductive coating 15.

[0068] Similarly, the thermally conductive coating 15 can also completely cover the top end 11a of the electrode assembly 11, or partially cover the top end 11a of the electrode assembly 11. For example, the electrode assembly 11 is usually formed by sequentially winding a positive electrode, a separator, and a negative electrode, and the top end 11a of the electrode assembly 11 is on the same side as the positive electrode, the separator, and the negative electrode. Therefore, the thermally conductive coating 15 can be selectively coated on the same side of the positive electrode, the separator, and the negative electrode to achieve complete coverage of the top end 11a of the electrode assembly 11; or, due to manufacturing process requirements, the negative electrode is usually partially covered in the width direction of the electrode assembly 11. The width of the negative electrode should be wider than that of the positive electrode to achieve complete coverage of the positive electrode. Therefore, in terms of structural dimensions, the negative electrode is wider than the positive electrode, and the separator covering the negative electrode is also wider than that of the positive electrode. This allows the separator in this part to directly contact the insulating member 14. Then, the thermally conductive coating 15 can be applied to this part of the separator, that is, to achieve partial coverage of the top part 11a of the electrode assembly 11 by the thermally conductive coating 15.

[0069] The battery cell 10 provided by this utility model is provided with a thermally conductive coating 15, and the thermally conductive coating 15 is provided on the top part 11a of the insulating member 14 and / or the electrode assembly 11 to increase the heat transfer rate between the top part 11a of the electrode assembly 11 and the outside world, thereby improving the heat exchange efficiency of the top of the battery cell 10, reducing the heat exchange difference between the top and bottom of the battery cell 10, and improving the performance of the battery cell 10 to a certain extent.

[0070] Please refer to Figures 4 and 5. In some embodiments, the electrode assembly 11 includes a positive electrode 111, a diaphragm 112, and a negative electrode 113. The positive electrode 111, the diaphragm 112, and the negative electrode 113 are sequentially wound or stacked. The negative electrode 113 includes a main body portion 1131 corresponding to the positive electrode 111 and a protrusion portion 1132 extending beyond the positive electrode 111 in the width direction of the main body portion 1131. The area of ​​the diaphragm 112 covering the protrusion portion 1132 is coated with a thermally conductive coating 15.

[0071] Understandably, the electrode assembly 11 is manufactured by unwinding the positive electrode 111, the separator 112, and the negative electrode 113 one by one on different rotating shafts, and then winding or stacking them on the same rotating shaft. Typically, the electrode assembly 11 consists of one layer of positive electrode 111, one layer of separator 112, and one layer of negative electrode 113 in the thickness direction. Of course, in some cases, it can also consist of one layer of positive electrode 111, one layer of separator 112, one layer of negative electrode 113, and another layer of separator 112.

[0072] Furthermore, in order to improve the stability and charging / discharging efficiency of the electrode assembly 11, the size of the negative electrode 113 is larger than that of the positive electrode 111. For example, in the width direction of the electrode assembly 11 (which is also the width direction of the positive electrode 111 and the width direction of the negative electrode 113), the width of the negative electrode 113 is greater than that of the positive electrode 111. Therefore, the negative electrode 113 includes a main body 1131 and a protruding part 1132. In the direction perpendicular to the large surface of the electrode assembly 11, the outer contour of the main body 1131 matches the outer contour of the positive electrode 111. The protruding part 1132 is the portion of the main body 1131 that extends beyond the positive electrode 111 in the width direction. At the same time, when the diaphragm 112 is covered, the protruding part 1132 also needs to be covered. That is, part of the diaphragm 112 extends beyond the positive electrode 111 to the outside. Therefore, a thermally conductive coating 15 will be applied to the part of the diaphragm 112 that covers the protruding part 1132 to improve the thermal conductivity between the electrode assembly 11 and the insulating member 14.

[0073] The heat conduction path from the top of the battery cell 10 to the outside is: negative electrode 113, separator 112, insulator 14, and top cover 13. Therefore, coating the separator 112 with a thermally conductive coating 15 can improve the transfer of heat generated during operation from the electrode assembly 11 to the insulator 14.

[0074] Thus, the protruding portion 1132 of the negative electrode 113 should be the part that first contacts the electrode assembly 11 and the insulator 14. Therefore, applying a thermally conductive coating 15 to the area of ​​the separator 112 covering the protruding portion 1132 can improve the heat exchange efficiency between the electrode assembly 11 and the insulator 14, thereby improving the heat exchange efficiency between the top of the battery cell 10 and the outside.

[0075] Referring to Figures 3 and 6, in some embodiments, the insulating member 14 has a bottom surface 14b facing the electrode assembly 11 and a top surface 14a facing the top cover 13, and the top surface 14a and / or the bottom surface 14b are coated with a thermally conductive coating 15.

[0076] Understandably, the insulating member 14 is disposed between the top cover 13 and the top end portion 11a of the electrode assembly 11. Therefore, the insulating member 14 should have an end face facing the top cover 13, i.e., the top surface 14a, and also have an end face facing the top end portion 11a of the electrode assembly 11, i.e., the bottom surface 14b. Then, depending on the actual use requirements, the thermally conductive coating 15 can be coated only on the top surface 14a, or only on the bottom surface 14b, or both the top surface 14a and the bottom surface 14b can be coated with the thermally conductive coating 15.

[0077] Therefore, the heat conduction path from the top of the battery cell 10 to the outside is: negative electrode 113, separator 112, insulating element 14, and top cover 13. Therefore, coating the insulating element 14 with a thermally conductive coating 15 can improve the transfer of heat generated during operation from the insulating element 14 to the top cover 13.

[0078] In other embodiments, the insulating member 14 also has a sidewall surface connecting the top surface 14a and the bottom surface 14b, and a thermally conductive coating 15 may be coated on the sidewall surface. Therefore, coating the sidewall surface of the insulating member 14 with the thermally conductive coating 15 ensures that the entire surface of the insulating member 14 is coated with the thermally conductive coating 15, thereby further improving the heat transfer efficiency of the insulating member 14.

[0079] Thus, a thermally conductive coating 15 is applied to the top surface 14a and / or bottom surface 14b of the insulating element 14 to improve the heat exchange capacity of the insulating element 14.

[0080] In some embodiments, a thermally conductive coating 15 may be applied to the area of ​​the diaphragm 112 covering the protrusion 1132; and a thermally conductive coating 15 may be applied to the insulating member 14.

[0081] Understandably, the area of ​​the separator 112 corresponding to the protrusion 1132 and the insulating member 14 are low thermal conductivity areas where heat exchange occurs from the top of the battery cell 10 outwards. That is, the heat generated during operation tends to concentrate in the area of ​​the separator 112 corresponding to the protrusion 1132 and the insulating member 14, ultimately leading to heat concentration in this area of ​​the separator 112 and the insulating member 14. Therefore, if a thermally conductive coating 15 is applied to the area of ​​the separator 112 covering the protrusion 1132, and a thermally conductive coating 15 is applied to the insulating member 14, the heat generated during operation can be further improved to quickly pass through this low thermal conductivity area, thereby alleviating the problem of large temperature differences between the top and bottom of the battery cell 10.

[0082] Referring to Figure 6, in one embodiment, the thermally conductive coating 15 includes an insulating substrate 151 and a thermally conductive filler 152 dispersed within the insulating substrate 151, wherein the thermally conductive filler 152 accounts for 5% to 60% of the total mass of the thermally conductive coating 15; or...

[0083] The thermal conductivity of the thermally conductive coating 15 is ≥2W / (m·K).

[0084] Understandably, the insulating substrate 151 is the main body of the thermally conductive coating 15, used to support and carry the thermally conductive filler 152, so that the thermally conductive filler 152 can maintain a certain shape and dimensional stability, facilitating its adhesion to the insulating component 14 and the diaphragm 112. The insulating substrate 151 can be an organic polymer, including but not limited to polyimide, polyamide, and epoxy resin. The thermally conductive filler 152 is the core of the thermally conductive coating 15's high thermal conductivity, and the thermally conductive filler 152 includes but is not limited to boron nitride and aluminum nitride.

[0085] The mass ratio of thermally conductive filler 152 to insulating substrate 151 is in the range of 5:95 to 60:40. Optionally, the mass ratio of thermally conductive filler 152 to insulating substrate 151 can be 5:95, 10:90, 15:85, 20:80, 25:75, 30:70, 35:65, 40:60, 45:55, 50:50, 55:45, 60:40, etc.

[0086] Furthermore, the overall thermal conductivity of the thermally conductive coating 15 is ≥2W / (m·K) to meet the temperature rise requirements of the electrode assembly 11.

[0087] Thus, the thermally conductive coating 15 is mainly composed of a thermally conductive filler 152 and an insulating substrate 151. The insulating substrate 151 serves as a load-bearing component, while the thermally conductive filler 152 provides high thermal conductivity. Furthermore, the mass ratio of the two components is adjusted according to actual application requirements.

[0088] In one embodiment, the thermally conductive filler 152 comprises any one or both of boron nitride and aluminum nitride, wherein the thermal conductivity of the thermally conductive filler 152 is ≥80 W / (m·K); or,

[0089] The insulating matrix 151 includes any one or more of polyimide, polyamide, and epoxy resin, wherein the molecular weight of the insulating matrix 151 is 8*10. 4 ~40*10 4 .

[0090] Understandably, appropriate thermally conductive filler 152 and insulating matrix 151 can be selected according to actual usage requirements. For example, thermally conductive filler 152 can be any one or two of boron nitride and aluminum nitride, and insulating matrix 151 can be any one or several of polyimide, polyamide and epoxy resin.

[0091] Please refer to Figure 7. In one embodiment, the method for preparing the thermally conductive coating 15 includes the following steps;

[0092] S001. The thermally conductive filler 152 is dispersed in a solvent to form a filler suspension, and the insulating matrix 151 is dispersed in the same solvent to form a polymer solution. Finally, the filler suspension and the polymer solution are mixed to form a mixture solution.

[0093] Understandably, in order to achieve uniform dispersion of the thermally conductive filler 152 in the insulating matrix 151, it is possible to first prepare the thermally conductive filler 152 into a filler suspension and prepare the insulating matrix 151 into a polymer solution, and then mix the two solutions to form a uniformly dispersed mixture solution.

[0094] Here, the type of solvent is not limited, as long as it can disperse the thermally conductive filler 152 and the insulating matrix 151. For example, the solvent can be NMP solvent (N-methyl-2-pyrrolidone).

[0095] S002. The mixture solution is coated and a thermally conductive coating 15 is formed after curing, wherein the curing temperature of the mixture solution is 80℃~140℃.

[0096] Understandably, curing allows the mixture solution to gradually form a film or layered structure, and is able to adhere to the surface of the diaphragm 112 and / or the insulator 14.

[0097] As shown in the figure, a filler suspension and a polymer solution are first obtained, and then the two are mixed to form a mixture solution. Finally, the mixture is cured to form a thermally conductive coating 15.

[0098] In one embodiment, the thickness μ of the thermally conductive coating 15 is (0.02~0.08) * the capacity of the battery cell 10.

[0099] Understandably, since the volume of the thermally conductive coating 15 occupies the space of the housing cavity of the casing 12, the thickness of the thermally conductive coating 15 affects the capacity of the battery cell 10 to a certain extent. In order to improve the thermal transmission efficiency without having a significant impact on the housing of the battery cell 10, the thickness of the thermally conductive coating 15 needs to be controlled. That is, the thickness of the thermally conductive coating 15 is μ = (0.02~0.08) * the capacity of the battery cell 10.

[0100] Optionally, the ratio of the thickness μ of the thermally conductive coating 15 to the capacity of the battery cell 10 can be 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, etc.

[0101] Therefore, in order to reduce the impact of the thickness of the thermally conductive coating 15 on the capacity of the battery cell 10, the thickness of the thermally conductive coating 15 must be controlled while ensuring a certain heat exchange efficiency.

[0102] In one embodiment, the thickness μ of the thermally conductive coating 15 is (0.033~0.066) * the capacity of the battery cell 10.

[0103] Optionally, the ratio of the thickness μ of the thermally conductive coating 15 to the capacity of the battery cell 10 can be 0.033, 0.04, 0.05, 0.066, etc.

[0104] By controlling the thickness of the thermally conductive coating 15 within the aforementioned range, the heat exchange efficiency at the top of the battery cell 10 can be improved while achieving a larger capacity of the battery cell 10.

[0105] The following examples characterize the effects of the thickness, coating location, and composition ratio of the thermally conductive coating 15 on the performance of the battery cell 10.

[0106] Please refer to Figures 3 to 7. In one specific embodiment, the battery cell 10 includes a housing 12, a top cover 13, an electrode assembly 11, an insulating component 14, and a thermally conductive coating 15.

[0107] The housing 12 has a receiving cavity and an open end, and a top cover 13 is provided on the open end of the housing 12; an electrode assembly 11 is placed in the receiving cavity, and the electrode assembly 11 has a top end portion 11a disposed toward the top cover 13 and a bottom end portion 11b disposed opposite to the top end portion 11a; an insulating member 14 is disposed between the top cover 13 and the top end portion 11a; and a thermally conductive coating 15 is coated on the insulating member 14 and the top end portion 11a.

[0108] Specifically, a thermally conductive coating 15 is applied to the area of ​​the diaphragm 112 covering the protrusion 1132.

[0109] The thermally conductive coating 15 includes an insulating substrate 151 and a thermally conductive filler 152 dispersed within the insulating substrate 151. The thermally conductive filler 152 is boron nitride with a thermal conductivity ≥80 W / (m·K). The insulating substrate 151 is polyimide with a molecular weight of 8*10⁻⁶. 4 ~40*10 4 .

[0110] Preparation method of thermally conductive coating 15: 50g of boron nitride is dispersed in NMP solvent to form a uniform boron nitride suspension; 50g of polyimide is dissolved in NMP solvent to form a polyimide solution; the boron nitride suspension and the polyimide solution are mixed evenly to obtain a mixture solution;

[0111] The mixture solution is applied to the area of ​​the diaphragm 112 covering the protrusion 1132 and the surface of the insulating member 14;

[0112] The mixture solution was cured and dried at 130°C to obtain a thermally conductive coating 15 with a thickness of 20 μm.

[0113] Example 1

[0114] 5g of boron nitride was dispersed in NMP solvent to form a uniform boron nitride suspension; 95g of polyimide was dissolved in NMP solvent to form a polyimide solution; the boron nitride suspension and the polyimide solution were mixed evenly to obtain a mixture solution;

[0115] The mixture solution is applied to the area of ​​the diaphragm 112 covering the protrusion 1132 and the surface of the insulating member 14;

[0116] The mixture solution is cured and dried at 130°C to obtain a thermally conductive coating 15 with a thickness of 10 μm.

[0117] The negative electrode 113, the separator 112, and the positive electrode 111 are wound in sequence to form a cylindrical electrode assembly 11. The separator 112 covers a 6mm wide area of ​​the protrusion 1132, and the separator 112 at the top of the electrode assembly 11 covers a 3mm wide area of ​​the protrusion 1132. The electrode assembly 11 is placed inside the housing 12, and an insulating member 14 and a top cover 13 are sequentially arranged. The capacity of the battery cell 10 is 300Ah.

[0118] Example 2

[0119] The difference from Example 1 is that the mass of boron nitride is 20g and the mass of polyimide is 80g.

[0120] Example 3

[0121] The difference from Example 1 is that the mass of boron nitride is 50g and the mass of polyimide is 50g.

[0122] Example 4

[0123] The difference from Example 1 is that the thickness of the thermally conductive coating 15 is 20 μm.

[0124] Example 5

[0125] The difference from Example 1 is that the mass of boron nitride is 20g, the mass of polyimide is 80g, and the thickness of the thermally conductive coating 15 is 20μm.

[0126] Example 6

[0127] The difference from Example 1 is that the mass of boron nitride is 50g, the mass of polyimide is 50g, and the thickness of the thermally conductive coating 15 is 20μm.

[0128] Example 7

[0129] The difference from Example 1 is that the mass of boron nitride is 20g, the mass of polyimide is 80g, the thickness of the thermally conductive coating 15 is 20μm, and the mixture solution is only coated on the area of ​​the diaphragm 112 covering the protrusion 1132.

[0130] Example 8

[0131] The difference from Example 1 is that the mass of boron nitride is 20g, the mass of polyimide is 80g, the thickness of the thermally conductive coating 15 is 20μm, and the mixture solution is only coated on the insulating part 14.

[0132] Example 9

[0133] The difference from Example 1 is that the thickness of the thermally conductive coating 15 is 6 μm.

[0134] Example 10

[0135] The difference from Example 1 is that the thickness of the thermally conductive coating 15 is 15 μm.

[0136] Example 11

[0137] The difference from Example 1 is that the thickness of the thermally conductive coating 15 is 24 μm.

[0138] Comparative Example 1

[0139] The separator 112 and the insulating element 14 of the same capacity battery are not coated with thermally conductive coating 15, and the remaining battery parameters are the same as those in the embodiments.

[0140] The batteries of the above embodiments and comparative examples were subjected to cycle tests. Specifically, the batteries were placed in an ambient temperature of 25°C and subjected to 1C / 1C accelerated cycling with a test voltage of 2.5V-3.65V and 100% DOD cycling. Two temperature sensing wires were set at the top and bottom of the batteries to monitor the temperature difference during the cycling process.

[0141] The thermal conductivity of the thermally conductive coating 15 is determined by coating a glass plate with the mixture solution from the preparation process of the thermally conductive coating 15, and then measuring the thermal conductivity on the glass plate after curing. Specifically, the heat flow method is used, where a calibrated heat flow sensor is used to measure the heat flow through the sample to obtain the absolute value of the thermal conductivity. During measurement, a sample of uniform thickness is inserted between two plates, and a certain temperature gradient is set. The heat flow through the sample is measured using the calibrated heat flow sensor, which is in contact with the sample between the plates. By measuring the sample thickness, the temperature gradient between the upper and lower plates, and the heat flow through the sample, the thermal conductivity of the sample can be calculated. λ=(Qh+Qc) / 2*L / ΔT

[0142] Where λ is the thermal conductivity of the sample, in W / (m·K); Qh is the heat flux output of the upper thermal sensor, in W / m 2 Qc is the heat flux output of the upper thermal sensor, in W / m³. 2 L is the thickness of the sample, in meters (m); ΔT is the temperature difference between the upper and lower surfaces of the sample, in kilometer (K).

[0143] Here, the sample can be a thermally conductive coating 15 or a diaphragm 112 coated with a thermally conductive coating 15. However, due to the excessive thickness of the insulating component 14, it is difficult to determine the thermal conductivity of the insulating component 14 and the thermal conductivity of the insulating component 14 coated with the thermally conductive coating 15 in the above manner. Therefore, the thermal conductivity system of the insulating component 14 can be determined based on its material.

[0144] As shown in the table above, the temperature rise at the top of the battery cell 10 is improved after the thermal conductive coating 15 is applied. Here, the temperature rise data of the top to the bottom of the battery cell 10 in Examples 1 to 8 and Comparative Example 1 can be referred to. Furthermore, the thicker the thermal conductive coating 15 and the higher the proportion of thermal conductive filler 152 in the thermal conductive coating 15, the more significant the improvement in the temperature rise at the top of the battery cell 10. Here, referring to Examples 1 to 3, it can be found that when the thickness of the thermal conductive coating 15 is the same, the higher the proportion of thermal conductive filler 152 in the thermal conductive coating 15, the smaller the temperature rise at the top to the bottom of the battery cell 10. At the same time, referring to Examples 1 and 4, 2 and 5, 3 and 6, 9, 10 and 11, it can be found that when the proportion of thermal conductive filler 152 in the thermal conductive coating 15 is the same, the thicker the thermal conductive coating 15, the smaller the temperature rise at the top to the bottom of the battery cell 10. Furthermore, the thermal conductivity of the thermally conductive coating 15 is related to the proportion of thermally conductive filler 152 in the thermally conductive coating 15, and is not related to the thickness of the thermally conductive coating 15. Finally, since the temperature difference between the top and bottom of the battery cell 10 is reduced, the lifespan of the corresponding battery cell 10 is also improved, as can be seen from the capacity retention rate after 1000cls in Examples 1 to 11 and Comparative Example 1.

[0145] According to some embodiments of this application, as shown in FIG2, this application also provides a battery device 100, which includes the battery cell 10 described above.

[0146] The battery device 100 also includes a housing 20, which has an internal receiving space for accommodating multiple battery cells 10. As shown in Figure 2, the housing 20 may include two parts, referred to here as the first part 21 and the second part 22. Please refer to Figures 2 and 3, which show one example of the first part 21 of the housing 20. The first part 21 and the second part 22 can be connected by fastening, bonding, or other methods to form the receiving space. Multiple battery cells 10 are connected in parallel, series, or mixed configurations and placed within the housing formed by the connection of the first part 21 and the second part 22. The shapes of the first part 21 and the second part 22 can be determined based on the shape formed by the combination of multiple battery cells 10.

[0147] According to some embodiments of this application, referring to FIG1, this application also provides an electrical device, which includes the battery device 100 in the above embodiments, the battery device 100 being used to store or provide electrical energy.

[0148] The technical solutions described in the embodiments of this application are applicable to various electrical devices that use battery cells 10, such as mobile phones, portable devices, laptops, electric vehicles, electric toys, power tools, vehicles 1000, ships and spacecraft, etc. For example, spacecraft include airplanes, rockets, space shuttles and spacecraft.

[0149] The examples of electrical devices in this application are based on the examples of the battery device 100 described above. The examples of electrical devices include all the technical effects of the examples of the battery device 100 described above, and will not be repeated here.

[0150] The above are merely preferred embodiments of this application, and only specifically describe the technical principles of this application. These descriptions are only for explaining the principles of this application and should not be construed as limiting the scope of protection of this application in any way. Based on this explanation, any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application, as well as other specific embodiments of this application that can be conceived by those skilled in the art without creative effort, should be included within the scope of protection of this application.

Claims

1. A battery cell, characterized in that, include: The housing has a receiving cavity and an open end. A top cover, which is disposed over the opening end of the housing; An electrode assembly, wherein the electrode assembly is disposed within the accommodating cavity, the electrode assembly having a top end portion disposed toward the top cover and a bottom end portion disposed opposite to the top end portion; An insulating element is disposed between the top cover and the top end portion; as well as, A thermally conductive coating is applied to at least a portion of the insulating element and / or at least a portion of the top portion.

2. The battery cell as described in claim 1, characterized in that: The electrode assembly includes a positive electrode, a separator, and a negative electrode. The positive electrode, the separator, and the negative electrode are sequentially wound or stacked. The negative electrode includes a main body portion corresponding to the positive electrode and a protruding portion extending beyond the positive electrode in the width direction of the main body portion. The area of ​​the protruding portion covered by the separator is coated with the thermally conductive coating.

3. The battery cell as described in claim 1, characterized in that: The insulating element has a bottom surface facing the electrode assembly and a top surface facing the top cover, and the thermally conductive coating is applied to the top surface and / or the bottom surface.

4. The battery cell according to any one of claims 1 to 3, characterized in that: The thermally conductive coating comprises an insulating substrate and thermally conductive fillers dispersed within the insulating substrate, wherein the thermally conductive fillers account for 5% to 60% of the total mass of the thermally conductive coating; or... The thermal conductivity of the thermally conductive coating is ≥2W / (m·K).

5. The battery cell as described in claim 4, characterized in that: The thermally conductive filler includes any one or both of boron nitride and aluminum nitride, wherein the thermal conductivity of the thermally conductive filler is ≥80 W / (m·K); or, The insulating matrix includes any one or more of polyimide, polyamide, and epoxy resin, wherein the molecular weight of the insulating matrix is ​​8*10. 4 Da~40*10 4 Da.

6. The battery cell as described in claim 4, characterized in that, The method for preparing the thermally conductive coating includes the following steps; The thermally conductive filler is dispersed in a solvent to form a filler suspension, and the insulating matrix is ​​dispersed in another set of the same solvents to form a polymer solution. Finally, the filler suspension and the polymer solution are mixed to form a mixture solution. The mixture solution is coated and, after curing, forms a thermally conductive coating, wherein the curing temperature of the mixture solution is 80℃~140℃.

7. The battery cell according to any one of claims 1 to 6, characterized in that: The thickness μ of the thermally conductive coating is (0.02~0.08) * the capacity of the battery cell.

8. The battery cell as described in claim 8, characterized in that: The thickness μ of the thermally conductive coating is (0.033~0.066) * the capacity of the battery cell.

9. A battery device, characterized in that, Includes the battery cell as described in any one of claims 1 to 8.

10. An electrical appliance, characterized in that, Includes the battery device as described in claim 9.

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