Battery monomer and preparation method thereof, shell battery for battery monomer and power utilization device

Abstract

The invention provides a battery monomer, a preparation method of the battery monomer, a shell battery for the battery monomer and a power utilization device. The battery monomer comprises a shell and an electrode assembly, the electrode assembly is arranged in the shell, and the shell comprises a shell body and a heat insulation film arranged on at least part of the outer surface of the shell body; the heat insulation film is prepared from the following components in parts by mass: 3 to 12 parts of polymer, 5 to 30 parts of heat insulation filler and 0.01 to 1 part of soaking filler. By controlling the proportion of the components of the heat insulation film, the heat insulation film has good heat insulation performance and heat conduction uniformity, so that the temperature distribution in the battery monomer is relatively consistent, and the situation that the battery performance is influenced due to the fact that the local temperature is too high or too low and other temperature differences are too large is prevented. The heat insulation film with good heat conduction uniformity can effectively block non-uniform transfer of heat, slow down the propagation speed of thermal runaway, prevent or delay thermal runaway of the battery, and provide more time and guarantee for safety protection of the battery.

Description

Technical Field

[0001] This application relates to the field of battery technology, and in particular to a battery cell and its preparation method, a battery casing for the battery cell, and an electrical device thereof. Background Technology

[0002] In recent years, the application range of batteries has become increasingly wide. Batteries are widely used in energy storage power systems such as hydropower, thermal power, wind power, and solar power plants, as well as in power tools, electric bicycles, electric motorcycles, electric cars, military equipment, aerospace, and many other fields. Due to the tremendous development of batteries, higher requirements have been placed on their energy density.

[0003] However, individual battery cells have high energy density, resulting in greater residual energy after thermal runaway. When a single battery cell experiences thermal runaway, heat is continuously conducted from that cell to adjacent cells, triggering thermal runaway across the entire battery and causing damage to the entire battery.

[0004] Therefore, how to prevent or delay thermal runaway of batteries is an urgent problem to be solved. Summary of the Invention

[0005] Therefore, it is necessary to provide a battery cell and its preparation method, a battery cell casing, and an electrical device to address how to prevent or delay battery thermal runaway.

[0006] The first aspect of this application provides a battery cell, including a housing and an electrode assembly, wherein the electrode assembly is disposed within the housing, and the housing includes a housing body and a heat insulation film disposed on at least a portion of the outer surface of the housing body; the heat insulation film comprises, by mass parts, 3 to 12 parts of polymer, 5 to 30 parts of heat insulation filler and 0.01 to 1 part of heat homogenizing filler.

[0007] In the aforementioned heat insulation film, too much heat-insulating filler will negatively impact the uniformity of thermal conductivity, while too little will reduce its heat insulation performance. Similarly, too much heat-equalizing filler will negatively impact the heat insulation performance, while too little will reduce its uniform thermal conductivity. Therefore, this application achieves both good heat insulation performance and uniform thermal conductivity by controlling the proportions of the aforementioned components in the heat insulation film.

[0008] The aforementioned battery cell includes a heat-insulating film on its outer surface. This heat-insulating film contains a specific composition, with heat-insulating fillers and heat-monopolating fillers connected by a polymer to form a film layer. Because it contains heat-insulating fillers, it has excellent heat insulation performance. Simultaneously, the heat-monopolating fillers within the heat-insulating film not only block heat transfer but also promote uniform heat conduction. Thus, the synergistic effect of the heat-insulating fillers and heat-monopolating fillers in the heat-insulating film provides both excellent heat insulation performance and uniform thermal conductivity. This allows the heat-insulating film to not only block heat and reduce the heat received inside the battery cell but also improve the uniformity of heat conduction. This results in a more uniform temperature distribution inside the battery cell, preventing excessively high or low temperatures that could negatively impact cycle performance and other battery performance characteristics. Furthermore, the heat-insulating film with good thermal conductivity uniformity effectively blocks uneven heat transfer, slows the propagation rate of thermal runaway, and prevents or delays battery thermal runaway, providing more time and protection for battery safety. In addition, a heat-insulating pad that provides both insulation and uniform thermal conductivity can reduce the difference between thermal expansion and contraction, decrease stress concentration, and extend battery life.

[0009] In addition, the above-mentioned heat insulation film has low thermal conductivity, so it can achieve good heat insulation effect with a very thin thickness. Therefore, it can be directly set on the outer surface of the shell body, which can not only reduce the volume of the heat insulation film, but also reduce the risk of displacement of the heat insulation film during transportation and other processes, and provide more stable heat insulation performance.

[0010] In some embodiments, the heat insulation film comprises, by weight, 3-12 parts of polymer, 7-15 parts of heat insulation filler, and 0.05-0.5 parts of heat homogenizing filler. By controlling the above components in the above proportions, the heat insulation performance and thermal conductivity uniformity of the heat insulation film can be further improved.

[0011] In some embodiments, the heat insulation film further includes, by weight, one or more of an adhesive, a dispersant, and a surfactant.

[0012] In some embodiments, one or more of the following conditions are met:

[0013] (1) In the heat insulation film, when the polymer is 3 to 12 parts by mass, the adhesive is 0.01 to 0.5 parts;

[0014] (2) When the polymer in the heat insulation film is 3 to 12 parts by mass, the dispersant is 0.01 to 0.5 parts;

[0015] (3) When the polymer in the heat insulation film is 3 to 12 parts by mass, the surfactant is 0.01 to 0.3 parts;

[0016] (4) The adhesive comprises one or more of polyvinylidene fluoride, polyvinyl alcohol, and polymethyl methacrylate;

[0017] (5) The dispersant includes one or more of dimethylethanolamine, methylethanolamine, and polycarboxylic acid;

[0018] (6) The surfactant includes polyoxyethylene alkyl ether.

[0019] In some embodiments, the thermal conductivity of the insulation film is 0.1 W / (m·K) to 0.6 W / (m·K).

[0020] In some embodiments, the mass fractions of the heat-insulating filler and the heat-soothing filler in the total mass of the heat-insulating filler and the heat-soothing filler are m1 and m2, respectively; the thermal conductivity of the heat-insulating filler and the heat-soothing filler are λ1 and λ2, respectively; and the estimated thermal conductivity of the mixture of the heat-insulating filler and the heat-soothing filler is λ. mix ;λ mix =(λ1m 1+ λ2m2) / (m 1+ m2); λ mix It ranges from 0.1 W / (m·K) to 0.5 W / (m·K).

[0021] In some embodiments, one or more of the following conditions are met:

[0022] (1) λ1 is 0.01W / (m·K)~0.8W / (m·K), and can be selected as 0.01W / (m·K)~0.04W / (m·K);

[0023] (2) λ2 is 1W / (m·K)~50W / (m·K), and can be selected as 1W / (m·K)~20W / (m·K).

[0024] In some embodiments, one or more of the following conditions are met:

[0025] (1) The polymer includes one or more of polyethylene terephthalate, polycarbonate, polyimide and acrylic copolymer;

[0026] (2) The heat insulation filler includes one or more of alumina, boron nitride, antimony trioxide, titanium dioxide and silicon dioxide;

[0027] (3) The heat-spreading filler includes one or more of metallic materials, alloy materials, and carbon materials;

[0028] (4) The average pore size of the heat insulation filler is 50 nm to 5 μm, and can be selected as 50 nm to 2 μm;

[0029] (5) The average pore size of the heat-equalizing filler is 1μm~10μm, and can be selected as 1μm~5μm.

[0030] In some embodiments, the metallic material includes one or more of copper particles, aluminum particles, gold particles, and silver particles; the alloy material includes copper-aluminum alloy particles; and the carbon material includes one or more of graphite, graphene, and carbon nanotubes.

[0031] In some embodiments, the thickness of the heat insulation film is 0.05mm to 0.8mm, and optionally 0.05mm to 0.2mm.

[0032] In some embodiments, one or more of the following conditions are met:

[0033] (1) The housing further includes a first insulating film, which is disposed between the housing body and the heat insulation film;

[0034] (2) The housing further includes a second insulating film, which is disposed on the surface of the heat insulation film away from the housing body.

[0035] In some embodiments, the casing body includes two relatively large sidewalls that form the large surface of the battery cell, and the heat insulation film is disposed at least on the outer side of the two relatively large sidewalls.

[0036] In a second aspect, this application provides a method for preparing a battery cell, including the step of preparing a casing, wherein the step of preparing the casing includes the following steps:

[0037] The polymer, 5-30 parts heat-insulating filler, and 0.01-1 parts heat-monopolizing filler, along with a solvent, are mixed in parts by weight to form a heat-insulating slurry.

[0038] The shell is prepared by forming an insulating film on at least a portion of the outer surface of the shell body using the insulating slurry.

[0039] In a third aspect, this application provides a housing for a battery cell, the housing comprising a housing body and a heat-insulating film disposed on at least a portion of the outer surface of the housing body; the heat-insulating film comprises, by mass parts, 3 to 12 parts of polymer, 5 to 30 parts of heat-insulating filler and 0.01 to 1 part of heat-monopolizing filler;

[0040] Alternatively, as defined in any of the preceding items regarding the housing.

[0041] In a fourth aspect, this application provides a heat insulation film, wherein the components of the heat insulation film, by mass parts, include 3 to 12 parts of polymer, 5 to 30 parts of heat insulation filler, and 0.01 to 1 part of heat homogenizing filler.

[0042] In a fifth aspect, this application provides a battery comprising one or more of the following: a battery cell provided in the first aspect of this application, a battery cell prepared by the preparation method provided in the second aspect of this application, a battery cell housing provided in the third aspect of this application, and a heat insulation film provided in the fourth aspect of this application.

[0043] In a sixth aspect of this application, an electrical device is provided, comprising one or more of the following: a battery cell provided in the first aspect of this application, a battery cell prepared by the method provided in the second aspect of this application, a battery cell housing provided in the third aspect of this application, a heat insulation film provided in the fourth aspect of this application, and a battery provided in the fifth aspect of this application.

[0044] The electrical device of this application includes the battery cell provided in this application, and therefore has at least the same advantages as the battery cell.

[0045] Details of one or more embodiments of this application are set forth in the following drawings and description. Other features, objects, and advantages of this application will become apparent from the specification, drawings, and claims. Attached Figure Description

[0046] To better describe and illustrate the embodiments or examples provided in this application, reference may be made to one or more accompanying drawings. Additional details or examples used to describe the drawings should not be considered as limiting the scope of any of the disclosed applications, the currently described embodiments or examples, or the best mode of conduct of these applications as currently understood. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0047] Figure 1 This is a schematic diagram of the structure of a battery cell according to one embodiment of this application;

[0048] Figure 2 for Figure 1 A schematic diagram of the cross-sectional structure of the battery cell shown.

[0049] Figure 3 for Figure 1 A magnified structural diagram of part B of the battery cell shown;

[0050] Figure 4 This is an exploded structural diagram of a battery cell according to an embodiment of this application;

[0051] Figure 5 This is a schematic diagram of the structure of a battery according to one embodiment of this application;

[0052] Figure 6 This is a schematic diagram of an electrical device that uses a battery as a power source according to one embodiment of this application;

[0053] Figure 7A schematic diagram of the assembly structure for uniform temperature performance testing;

[0054] Figure 8 The graph shows the temperature uniformity performance test results of the battery cell prepared in Comparative Example 1.

[0055] Figure 9 The graph shows the temperature uniformity test results of the battery cell prepared in Example 1.

[0056] Explanation of reference numerals in the attached figures:

[0057] 20. Battery cell; 21. Casing; 211. Casing body; 212. Heat insulation film; 213. Insulating film; 22. Electrode assembly; 23. Cover plate;

[0058] 30. Battery; 311. Upper casing; 312. Lower casing; 32. Battery module;

[0059] 40. Electrical appliances. Detailed Implementation

[0060] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0061] The "range" disclosed in this application can be defined in the form of a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints; any endpoint can be independently included or excluded, and they can be combined arbitrarily, meaning any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is expected that ranges of 60-110 and 80-120 are also included. Furthermore, if minimum range values ​​1 and 2 are listed, and maximum range values ​​3, 4, and 5 are also listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this document; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, stating that a parameter is an integer ≥2 is equivalent to disclosing that the parameter is, for example, an integer 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc. For instance, stating that a parameter is an integer selected from "2-10" is equivalent to listing the integers 2, 3, 4, 5, 6, 7, 8, 9, and 10.

[0062] In this application, the terms "multiple" or "various" are used unless otherwise specified, referring to a quantity greater than or equal to 2. For example, "one or more" means one or more types.

[0063] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0064] 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 or implementation 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. The term "implementation" as used herein has a similar understanding.

[0065] Those skilled in the art will understand that the order in which the steps are written in the methods of various embodiments or examples does not imply a strict execution order and does not constitute any limitation on the implementation process. The detailed execution order of each step should be determined by its function and possible internal logic. Unless otherwise specified, all steps of this application may be performed sequentially or randomly, preferably sequentially. For example, if the method includes steps (a) and (b), it means that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, if the method may also include step (c), it means that step (c) can be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0066] In this application, unless otherwise specified, A (e.g., B) means that B is a non-limiting example of A, and it is understood that A is not limited to B.

[0067] In this application, "optionally," "optionally," and "optional" mean that something is optional, that is, it means that it is selected from either "with" or "without." If there are multiple "optional" entries in a technical solution, unless otherwise specified and there are no contradictions or mutual constraints, each "optional" entry shall be independent.

[0068] Currently, judging from market trends, the application of batteries is becoming increasingly widespread. Batteries, especially power batteries, are not only used in energy storage power systems such as hydropower, thermal power, wind power, and solar power plants, but also widely used in electric vehicles such as electric bicycles, electric motorcycles, and electric cars, as well as other fields. With the continuous expansion of the application areas of power batteries, the market demand for them is also constantly increasing.

[0069] A battery cell is the smallest unit that makes up a battery. A battery can include one or more battery cells, and multiple battery cells can be connected in series, parallel, or a combination thereof. A combination thereof means that multiple battery cells are connected in both series and parallel.

[0070] Multiple battery cells can be interconnected and arranged in a specific order, then directly housed within a casing to assemble a battery. Alternatively, multiple battery cells can be first assembled into a battery module, then interconnected to form a whole, and finally housed within a casing to form a battery.

[0071] To address the aforementioned battery thermal runaway issue and reduce the overall damage and risk to the battery, research has found that while heat insulation is crucial for batteries, the uniformity of heat conduction is equally important. When a single cell experiences thermal runaway, heat spreads rapidly. If the thermal insulation film is unevenly conductive, areas with excessively high thermal conductivity may accelerate the propagation of thermal runaway to surrounding cells, triggering a chain reaction and leading to a serious safety incident for the entire battery pack. Furthermore, uneven thermal conduction can cause uneven thermal expansion and contraction within the battery, resulting in stress concentration. Batteries subjected to prolonged stress concentration are more susceptible to internal structural damage.

[0072] One or more embodiments of this application provide a battery cell and a method for preparing the same, a battery cell casing, and an electrical device.

[0073] Please see Figure 1 , Figure 2 and Figure 3 The first aspect of this application provides a battery cell 20, including a housing 21 and an electrode assembly 22, wherein the electrode assembly 22 is disposed within the housing 21, and the housing 21 includes a housing body 211 and a heat insulation film 212 disposed on at least a portion of the outer surface of the housing body 211; the heat insulation film 212 comprises, by mass parts, 3 to 12 parts of polymer, 5 to 30 parts of heat insulation filler and 0.01 to 1 part of heat homogenizing filler.

[0074] In the aforementioned heat insulation film 212, too much heat insulation filler will negatively impact the heat conduction uniformity of the film, while too little will reduce its heat insulation performance. Similarly, too much heat homogenizing filler will negatively impact the heat insulation performance of the film, while too little will reduce its heat conduction uniformity. Therefore, this application achieves both good heat insulation performance and good heat conduction uniformity by controlling the proportions of the aforementioned components in the heat insulation film 212.

[0075] The aforementioned battery cell 20 has a casing 21 including a heat-insulating film 212 disposed on the outer surface of the casing body 211. This heat-insulating film 212 contains a specific composition, with heat-insulating fillers and heat-monopolating fillers connected by a polymer to form a film layer. Since the heat-insulating film 212 contains heat-insulating fillers, it has good heat insulation performance. Simultaneously, the heat-monopolating fillers in the heat-insulating film 212 not only block heat transfer but also promote uniform heat conduction. Thus, the heat-insulating fillers and heat-monopolating fillers in the heat-insulating film 212 work synergistically, combining good heat insulation performance and uniform thermal conductivity. This allows the heat-insulating film 212 to not only block heat and reduce the heat received inside the battery cell but also improve the uniformity of heat conduction. This results in a more uniform temperature distribution inside the battery cell, preventing excessively high or low temperatures that could affect battery performance, such as cycle performance. Furthermore, the 212 thermal insulation film, with its excellent thermal conductivity uniformity, effectively blocks uneven heat transfer, slows the propagation of thermal runaway, and prevents or delays battery thermal runaway, providing more time and protection for battery safety. In addition, the thermally insulating and uniformly conductive insulation pad can reduce differences in thermal expansion and contraction, decrease stress concentration, and extend battery life.

[0076] In addition, the thermal conductivity of the above-mentioned heat insulation film 212 is low, so it can achieve good heat insulation effect with a very thin thickness. Therefore, by directly setting it on the outer surface of the shell body 211, not only can the volume of the heat insulation film 212 be reduced, but also the risk of displacement of the heat insulation film 212 during transportation can be reduced, and more stable heat insulation performance can be provided.

[0077] It should be noted that the housing 21 refers to a structure that can be used to accommodate the electrode assembly 22. Specifically, the housing body 211 has a receiving cavity formed inside for accommodating the electrode assembly 22.

[0078] In this application, "battery cell" refers to the basic unit capable of converting chemical energy into electrical energy, and electrode assembly 22 refers to the component in battery cell 20 where electrochemical reactions occur to convert chemical energy into electrical energy. One or more electrode assemblies 22 can be housed inside the casing 211 of battery cell 20. Furthermore, battery cell 20 typically includes at least a positive electrode, a negative electrode, and an electrolyte. During battery charging and discharging, active ions repeatedly insert and extract between the positive and negative electrodes. The electrolyte acts as a conductor for active ions between the positive and negative electrodes.

[0079] Furthermore, the electrode assembly 22 also includes a separator disposed between the positive electrode and the negative electrode. Furthermore, taking the electrolyte as an example, the electrolyte is immersed in the electrode assembly 22. The battery cell 20 may contain one or more electrode assemblies 22, which can be selected by those skilled in the art according to specific practical needs.

[0080] In some embodiments, the polymer comprises one or more of polyethylene terephthalate (PET), polycarbonate (PC), polyimide (PI), and acrylic copolymers. Optionally, the polymer comprises one or more of polyethylene terephthalate (PET), polycarbonate (PC), and polyimide (PI).

[0081] As an example, the number of polymer parts can be 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12 parts, or within the range formed by any two of the above point values ​​as endpoints; further, it can be 4 to 8 parts, or 4 to 6 parts.

[0082] In some embodiments, the insulating filler includes, but is not limited to, one or more of alumina, boron nitride, antimony trioxide, titanium dioxide, and silica. Further, the silica may be, but is not limited to, silica aerogel.

[0083] The particle size of the heat insulation filler and the heat homogenizing filler affects the contact area and mixing uniformity between them, which in turn affects the heat insulation performance and thermal conductivity uniformity of the heat insulation film.

[0084] Furthermore, the average pore size of the heat-insulating filler is 50 nm to 5 μm, and can be optionally 50 nm to 2 μm. Within this range, the heat-insulating film can achieve both better heat insulation performance and uniform thermal conductivity. As an example, the average pore size of the heat-insulating filler can be 50 nm, 100 nm, 500 nm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, or within a range formed by any two of the above values ​​as endpoints.

[0085] In this application, the average pore size can be obtained by nitrogen adsorption / desorption testing.

[0086] As an example, the number of parts of the thermal insulation filler can be 5, 6, 7, 7.5, 8, 9, 10, 11, 12, 13, 14, 15, 18, 20, 22, 25, 26, 28, or 30 parts, or within the range of any two of the above points as end values; further, it can be 7 to 15 parts, or 7 to 13 parts.

[0087] In some embodiments, the heat-equalizing filler comprises one or more of metallic, alloy, and carbon materials. Within this range, the insulation film can achieve both better thermal insulation performance and uniform thermal conductivity.

[0088] Furthermore, the metallic material includes one or more of copper particles, aluminum particles, gold particles, and silver particles. The alloy material includes copper-aluminum alloy particles, and the carbon material includes one or more of graphite, graphene, and carbon nanotubes.

[0089] Furthermore, the average pore size of the heat-spreading packing is 1μm to 10μm, and can be selected as 1μm to 5μm. As an example, the average pore size of the heat-spreading packing can be 50nm, 100nm, 500nm, 1μm, 2μm, 3μm, 4μm, 5μm, or within the range formed by any two of the above point values ​​as endpoints.

[0090] As an example, the heat-equalizing filler can be 0.01 parts, 0.02 parts, 0.03 parts, 0.05 parts, 0.08 parts, 0.1 parts, 0.2 parts, 0.3 parts, 0.4 parts, 0.5 parts, 0.6 parts, 0.7 parts, 0.8 parts, 0.9 parts, or 1 part, or within the range formed by any two of the above point values ​​as endpoints; further, it can be 0.01 to 1 part, or 0.05 to 0.5 parts.

[0091] In some embodiments, the thermal conductivity of the insulation film is 0.1 W / (m·K) to 0.6 W / (m·K).

[0092] In some embodiments, the mass fractions of the heat-insulating filler and the heat-soothing filler in the total mass of the heat-insulating filler and the heat-soothing filler are m1 and m2, respectively; the thermal conductivity of the heat-insulating filler and the heat-soothing filler are λ1 and λ2, respectively; and the estimated thermal conductivity of the mixture of the heat-insulating filler and the heat-soothing filler is λ. mix ;λ mix =(λ1m 1+ λ2m2) / (m 1+ m2); λ mix It ranges from 0.1 W / (m·K) to 0.5 W / (m·K).

[0093] The estimated thermal conductivity of the mixture of the insulating filler and the heat-spreading filler is used to determine the mass content of each filler in the total mass of the insulating filler and the heat-spreading filler, thereby better controlling the thermal insulation film to obtain the required thermal conductivity.

[0094] In some embodiments, λ1 is 0.01 W / (m·K) to 0.8 W / (m·K), and can be selected as 0.01 W / (m·K) to 0.04 W / (m·K). As an example, λ1 can be 0.01 W / (m·K), 0.05 W / (m·K), 0.1 W / (m·K), 0.2 W / (m·K), 0.3 W / (m·K), 0.4 W / (m·K), 0.5 W / (m·K), 0.6 W / (m·K), 0.7 W / (m·K), 0.8 W / (m·K), or a range formed by any two of the above point values ​​as endpoints.

[0095] In some embodiments, λ2 is 1 W / (m·K) to 50 W / (m·K), and can be selected as 1 W / (m·K) to 20 W / (m·K). As an example, λ2 can be 1 W / (m·K), 5 W / (m·K), 10 W / (m·K), 12 W / (m·K), 15 W / (m·K), 20 W / (m·K), 25 W / (m·K), 30 W / (m·K), 35 W / (m·K), 40 W / (m·K), 45 W / (m·K), 50 W / (m·K), or a range defined by any two of the above values ​​as endpoints. Controlling λ2 within the above range can reduce the estimated thermal conductivity λ. mix The difference between the thermal conductivity of the insulation film and the thermal conductivity of the heat insulation film makes the thermal conductivity of the insulation film close to the estimated thermal conductivity λ. mix .

[0096] In some embodiments, the thickness of the heat insulation film is 0.05mm to 0.8mm, and optionally 0.05mm to 0.2mm. As an example, the thickness of the heat insulation film can be 0.05mm, 0.1mm, 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, or within a range formed by any two of the above values ​​as endpoints.

[0097] In this paper, the thickness can be measured using the following method. The equipment used is a Mitutoyo 547-301 thickness gauge with an accuracy of ≤0.01mm. During the test, both the composite insulation film and the test surface of the Mitutoyo 547-301 thickness gauge must be parallel to the ground. The test locations are the four corners and the center area, totaling five locations. The average value of these five locations is taken as the test value.

[0098] In some embodiments, the heat insulation film comprises, by weight, 3-12 parts of polymer, 7-15 parts of heat insulation filler, and 0.05-0.5 parts of heat homogenizing filler. By controlling the above components in the above proportions, the heat insulation performance and thermal conductivity uniformity of the heat insulation film can be further improved.

[0099] In some embodiments, the heat insulation film further includes an adhesive. When the polymer comprises 3 to 12 parts by weight in the heat insulation film, the adhesive comprises 0.01 to 0.5 parts by weight.

[0100] Furthermore, the adhesive comprises one or more of polyvinylidene fluoride (PVDF), polyvinyl alcohol (PVA), and polymethyl methacrylate (PMMA). The adhesive can bond and fix the heat-insulating filler and heat-monopolating filler to the polymer, thereby improving the adhesion of the heat-insulating film.

[0101] As an example, the number of parts of adhesive can be 0.01 parts, 0.02 parts, 0.03 parts, 0.05 parts, 0.08 parts, 0.1 parts, 0.2 parts, 0.3 parts, 0.4 parts, 0.5 parts, or within a range consisting of any two of the above point values ​​as endpoints.

[0102] In some embodiments, the heat insulation film further includes a dispersant. When the polymer comprises 3 to 12 parts by weight in the heat insulation film, the dispersant comprises 0.01 to 0.5 parts by weight.

[0103] Furthermore, the dispersant includes one or more of dimethylethanolamine, methylethanolamine, and polycarboxylic acid. The dispersant can improve the dispersibility of other components during the preparation of the heat insulation film, thereby improving processing performance and enhancing the dispersibility of other components in the heat insulation film.

[0104] As an example, the number of parts of the dispersant can be 0.01 parts, 0.02 parts, 0.03 parts, 0.05 parts, 0.08 parts, 0.1 parts, 0.2 parts, 0.3 parts, 0.4 parts, 0.5 parts, or within the range formed by any two of the above point values ​​as endpoints.

[0105] In some embodiments, the heat insulation film further includes a surfactant. When the polymer comprises 3 to 12 parts by weight in the heat insulation film, the surfactant comprises 0.01 to 0.3 parts by weight.

[0106] Furthermore, the surfactant includes polyoxyethylene alkyl ethers. Surfactants can improve the stability of other components during the preparation of the heat insulation film, thereby improving processing performance and enhancing the stability of the heat insulation film. Furthermore, the polyoxyethylene alkyl ethers include, but are not limited to, one or more of polyoxyethylene nonylphenol ether and polyoxyethylene dodecyl ether.

[0107] As an example, the amount of surfactant can be 0.01 parts, 0.02 parts, 0.03 parts, 0.05 parts, 0.08 parts, 0.1 parts, 0.2 parts, or 0.3 parts, or any two of the above point values ​​as end values ​​within a range.

[0108] In some embodiments, the heat insulation film contains, by weight, 3 to 12 parts of polymer, 7 to 15 parts of heat insulation filler, 0.05 to 0.5 parts of heat-equalizing filler, 0.01 to 0.5 parts of adhesive, 0.01 to 0.5 parts of dispersant, and 0.01 to 0.3 parts of surfactant.

[0109] In some embodiments, the polymer in the heat insulation film comprises 5% to 40% by mass, the heat insulation filler comprises 50% to 75%, and the heat homogenizing filler comprises 0.1% to 20%.

[0110] Furthermore, in the heat insulation film, the polymer comprises 25% to 40% by mass percentage, the heat insulation filler comprises 60% to 75%, and the heat homogenizing filler comprises 0.1% to 5%.

[0111] Furthermore, in the heat insulation film, by mass percentage, the polymer is 27%~38%, the heat insulation filler is 62%~73%, and the heat equalization filler is 0.1%~3%.

[0112] As an example, in the heat insulation film, the polymer, by mass percentage, can be 5%, 10%, 15%, 20%, 25%, 27%, 30%, 31%, 32%, 35%, 36%, 37%, 40%, or within a range consisting of any two of the above point values ​​as endpoints, and so on below.

[0113] As an example, in the heat insulation film, the heat insulation filler, by mass percentage, can be 50%, 55%, 60%, 65%, 66%, 67%, 70%, 75%, or within the range formed by any two of the above point values ​​as endpoints.

[0114] As an example, in a heat insulation film, the heat-monopolizing filler, by mass percentage, can be 0.1%, 0.12%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.1%, 1.2%, 1.5%, 2%, 2.2%, 2.3%, 2.5%, 3%, 4%, 5%, 10%, 15%, or 20%, or within the range defined by any two of the above values ​​as endpoints, and further can be 0.1% to 3%, or 0.1% to 2.5%, or 0.1% to 1%. Controlling the heat-monopolizing filler within the above range can reduce the estimated thermal conductivity λ. mix The difference between the thermal conductivity of the insulation film and the thermal conductivity of the heat insulation film makes the thermal conductivity of the insulation film close to the estimated thermal conductivity λ. mix .

[0115] In some embodiments, the adhesive, dispersant, and surfactant in the heat insulation film are, by weight percentage, 0.1% to 5%. Further, the adhesive, dispersant, and surfactant in the heat insulation film are, by weight percentage, 0.1% to 3%.

[0116] As an example, in the heat insulation film, the adhesive, dispersant, and surfactant, by mass percentage, may be 0.1%, 0.12%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.1%, 1.2%, 1.5%, 2%, 2.2%, 2.3%, 2.5%, 3%, 4%, 5%, or within the range formed by any two of the above values ​​as endpoints, and may further be 0.1% to 2%, or 0.1% to 1.5%.

[0117] In some embodiments, the housing 21 further includes a first insulating film (not shown), disposed between the housing body and the heat insulation film. Thus, the first insulating film is first disposed on at least a portion of the outer surface of the housing body, and then the heat insulation film is disposed on the outer surface of the first insulating film. Further, the first insulating film may cover part or all of the outer surface of the housing body. The heat insulation film covers part or all of the outer surface of the first insulating film.

[0118] Furthermore, both the first insulating film and the heat-insulating film can be applied to the shell body via an adhesive layer. In some embodiments, the heat-insulating film can also be formed directly on the target surface through a process.

[0119] Please see Figure 3 One embodiment of this application provides a battery cell 20. The battery cell 20 includes a battery cell housing 21 and an electrode assembly 22, the electrode assembly 22 being housed within the housing 21.

[0120] The housing 21 includes a housing body 211, a heat insulation film 212, and an insulating film 213. The heat insulation film 212 is disposed on at least a portion of the outer surface of the housing body 211. The insulating film 213 is disposed on the outer surface of the housing body 211 and covers at least a portion of the heat insulation film 212.

[0121] In some embodiments, the housing 21 further includes a second insulating film 213 disposed on the surface of the heat insulation film 212 away from the housing body 211. Thus, the heat insulation film 212 is first disposed on at least a portion of the outer surface of the housing body 211, and then the second insulating film 213 is disposed on the outer surface of the heat insulation film 212. Further, the heat insulation film 212 may cover part or all of the outer surface of the housing body 211. The second insulating film 213 covers part or all of the outer surface of the heat insulation film 212.

[0122] Furthermore, the second insulating film 213 can be applied to the heat insulation film 212 via an adhesive layer. Each adhesive layer is made of silicone adhesive. Silicone adhesive layers are heat-resistant and have high structural strength.

[0123] Understandably, in some embodiments, the housing may simultaneously include a first insulating film and a second insulating film 213. The first insulating film and the second insulating film 213 each independently include a blue film.

[0124] Please see Figure 4 In some embodiments of this application, the battery cell housing 21 further includes an end cap 23. The housing 21 has an opening communicating with a receiving cavity, and the end cap 23 is used to seal the opening disposed in the housing 21 to form a sealed space. The electrode assembly 22 is housed within the sealed space of the housing 21.

[0125] Furthermore, an electrode post is provided protruding on the end cap 23. The electrode post is a component used to electrically connect with the electrode assembly 22 to conduct electrical energy from the electrode assembly 22.

[0126] Furthermore, during the connection process between the electrode assembly 22 and the electrode post, since the area where the electrode post can connect with the electrode assembly 22 is relatively small, a welding pressure ring is usually required to ensure a stable connection between the electrode assembly 22 and the electrode post. After setting the welding pressure ring, a sealing ring is required to increase the sealing between the electrode post and the end cap 23. In addition, to prevent the electrode assembly 22 from directly contacting other parts of the end cap 23 besides the electrode post, upper and lower plastic seals are required between the electrode assembly 22 and the end cap 23 for insulation.

[0127] It is understood that the shape of the battery cell 20 includes, but is not limited to, square or cylindrical shapes, and the shape of the casing 211 includes, but is not limited to, square or cylindrical shapes. The heat insulation film 212 can be fitted according to the shape of the battery cell 20.

[0128] For example, Figure 1 and Figure 2 The example shown is a square-structured battery cell 20. Both the battery cell 20 and the casing 211 are square in shape.

[0129] Furthermore, the casing body 211 includes two relatively large sidewalls that constitute the large surface area of ​​the battery cell. Furthermore, a heat insulation film 212 is disposed at least on the outer side of the two relatively large sidewalls; even further, the heat insulation film 212 is disposed on the entire outer surface of the casing body 211. Understandably, the casing body 211 includes three relatively large sidewalls, the area of ​​which the two relatively large sidewalls is larger than any one of the other two relatively large sidewalls.

[0130] It is understood that if the battery cell 20 and the casing body 211 are cylindrical, the casing body 211 includes a cylindrical sidewall (i.e., a larger sidewall) that constitutes the large surface of the battery cell 20, and the heat insulation film 212 is disposed on the cylindrical sidewall.

[0131] Furthermore, one or both ends of the housing 21 are provided with openings, which are sealed in conjunction with the end cap 23.

[0132] Furthermore, the housing 21 is a cuboid housing, and the opening direction of the housing 21 is the height direction of the housing 21. Furthermore, the housing 21 has openings at both ends, and the two openings are arranged opposite each other in the height direction of the housing 21. Further, as a non-limiting example, the height of the housing 21 is 80mm to 210mm; further, as a non-limiting example, the length of the housing 21 is 90mm to 240mm; further, as a non-limiting example, the width of the housing 21 is 20mm to 80mm.

[0133] Furthermore, the battery cell 20 and the casing 21 are cuboid casings, and the heat insulation film 212 is disposed on the side of the larger area of ​​the battery cell 20. This larger area of ​​the side is perpendicular to the width direction mentioned above, that is, it is the side formed by the two sides in the length direction and the height direction mentioned above.

[0134] As a further, non-limiting example, the wall thickness of the shell body 211 is 0.5 mm to 0.8 mm.

[0135] The casing 211 of the battery cell 20 can be a rigid casing, such as a hard plastic casing, an aluminum alloy casing, or a steel casing. Further, the casing 211 can be an aluminum alloy casing; for example, a ternary aluminum alloy casing or a quinary aluminum alloy casing.

[0136] Furthermore, the aluminum alloy of the three-element aluminum alloy shell comprises the following components by mass percentage: aluminum ≥ 99.6%, copper ≤ 0.05%, iron ≤ 0.35%, magnesium ≤ 0.03%, manganese ≤ 0.03%, silicon ≤ 0.25%, titanium ≤ 0.03%, vanadium ≤ 0.05%, zinc ≤ 0.05%, and other individual elements ≤ 0.03%.

[0137] Furthermore, the aluminum alloy of the five-series aluminum alloy shell comprises the following components by mass percentage: aluminum ≥ 96.7%, copper ≤ 0.05% ≤ 0.2%, iron ≤ 0.7%, manganese ≤ 1.5%, silicon ≤ 0.6%, zinc ≤ 0.1%, other individual element components ≤ 0.05%, and other element total components ≤ 0.15%.

[0138] In a second aspect, this application provides a method for preparing any of the above-mentioned battery cells, including a step of preparing a casing, wherein the step of preparing the casing includes the following steps S10 to S20:

[0139] S10. The polymer, heat insulation filler and heat homogenizing filler are mixed with solvent in the above-mentioned mass proportions to form a heat insulation slurry.

[0140] In some embodiments, the solvent includes, but is not limited to, one or more of ethanol, acetone, butanediol, methylpyrrolidone (NMP), toluene, xylene, N,N-dimethylformamide (DMF), tetrahydrofuran (THF), and water. The solvent is used to dissolve the polymer and prepare the heat-insulating slurry. Optionally, the solvent includes one or more of methylpyrrolidone (NMP) and N,N-dimethylformamide (DMF).

[0141] In some embodiments, the mass ratio of solvent to polymer is 25 to 40:1.

[0142] Furthermore, the above mixing can be promoted by means of mechanical stirring or other methods.

[0143] S20. Using the heat-insulating slurry, a heat-insulating film is formed on at least a portion of the outer surface of the shell body to prepare the shell.

[0144] In some embodiments, the heat insulation film is formed using the heat insulation slurry, which can be formed by processes such as solution casting, magnetron sputtering, chemical vapor deposition, and solution spin coating.

[0145] In some embodiments, a heat insulation film can be formed on the substrate first, and then the heat insulation film can be disposed on at least a portion of the outer surface of the shell body. Further, the heat insulation film can be directly applied to multiple outer surfaces of the shell body; alternatively, a separate heat insulation film can be disposed on different surfaces of the shell body.

[0146] In some embodiments, an insulating film can also be formed directly on at least a portion of the outer surface of the shell body using an insulating slurry.

[0147] In one specific example, step S20 includes sequentially coating, drying, and cold-pressing the insulating slurry to obtain an insulating film. The insulating film is then applied to at least a portion of the outer surface of the shell body.

[0148] Furthermore, the method for preparing the above-mentioned battery cell also includes step S30, which involves setting an electrode assembly within the casing. Understandably, the order of steps S30 and S20 is not limited; step S30 may precede step S20, or they may be performed simultaneously.

[0149] A third aspect of this application provides a housing for a battery cell, the housing comprising a housing body and a heat-insulating film disposed on at least a portion of the outer surface of the housing body; the heat-insulating film comprises, by weight parts, 3-12 parts of polymer, 5-30 parts of heat-insulating filler, and 0.01-1 parts of heat-monopolating filler. The battery cell housing of this application has been described in detail above and will not be repeated here.

[0150] In a fourth aspect, this application provides a heat insulation film, wherein the components of the heat insulation film, by weight parts, include 3 to 12 parts of polymer, 5 to 30 parts of heat insulation filler, and 0.01 to 1 part of heat homogenizing filler. The heat insulation film of this application has been described in detail above and will not be repeated here.

[0151] In a fifth aspect, this application provides a battery comprising one or more of the following: a battery cell provided in the first aspect of this application, a battery cell prepared by the preparation method provided in the second aspect of this application, a battery cell housing provided in the third aspect of this application, and a heat insulation film provided in the fourth aspect of this application.

[0152] In some embodiments, a battery includes one or more battery cells 20.

[0153] Since the battery cell 20 has a heat insulation film 212 inside its housing 21, there is no need to install heat insulation pads between the battery cells 20, which saves space and increases the arrangement density of the battery cells 20.

[0154] It is understandable that, to further improve thermal insulation performance, the battery may optionally include a thermal insulation pad disposed between at least two adjacent battery cells 20. Optionally, a thermal insulation pad may be disposed between any two adjacent battery cells 20. It is also understood that the aforementioned thermal insulation pad may be disposed between the battery cell 20 and the inner wall of the battery casing.

[0155] Understandably, after multiple battery cells 20 are interconnected and arranged in a certain order, they can be directly housed in a casing to assemble a battery. Alternatively, multiple battery cells 20 can be assembled into a battery module, or multiple battery modules can be further interconnected to form a whole, and finally, the entire battery module can be housed in a casing to form a battery.

[0156] Figure 5The example battery 30 includes a battery case and multiple battery modules 32 disposed within the battery case. The battery case includes an upper housing 311 and a lower housing 312, with the upper housing 311 covering the lower housing 312 to form a closed space for accommodating the battery modules 32. The multiple battery modules 32 can be arranged in any manner within the battery case. Each battery module 32 includes at least one battery cell 20. The number of battery cells 20 contained in the battery module 32 can be one or more, and those skilled in the art can select an appropriate number based on the application and capacity of the battery module 32.

[0157] The aforementioned battery cell 20 includes, but is not limited to, lithium-ion batteries.

[0158] In a sixth aspect of this application, an electrical device is provided, comprising one or more of the following: a battery cell provided in the first aspect of this application, a battery cell prepared by the method provided in the second aspect of this application, a battery cell housing provided in the third aspect of this application, a heat insulation film provided in the fourth aspect of this application, and a battery provided in the fifth aspect of this application.

[0159] The electrical device of this application includes the battery cell provided in this application or the battery provided in this application, and therefore has at least the same advantages as the battery cell or battery.

[0160] The aforementioned battery can be a power source for an electrical device or an energy storage unit for that device. Electrical devices can include, but are not limited to, mobile devices, electric vehicles, electric trains, ships, and satellites. Mobile devices can be, for example, mobile phones and laptops; electric vehicles can be, for example, pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc., but are not limited to these.

[0161] Figure 6 This is an example of an electrical device 40. This electrical device 40 is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. To meet the high power and high energy density requirements of this electrical device, a battery pack or battery module can be used.

[0162] Another example device could be a mobile phone, tablet, or laptop. These devices typically require a slim and lightweight design and can be powered by a battery.

[0163] To make the technical problems, technical solutions, and beneficial effects solved by this application clearer, the application will be further described in detail below with reference to embodiments and accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit this application or its applications. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0164] Where specific techniques or conditions are not specified in the examples, they shall be performed in accordance with the techniques or conditions described in the literature in this field or in accordance with the product instructions. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0165] Example 1

[0166] (1) Preparation of heat insulation film.

[0167] The raw material components for preparing the heat insulation film, by mass parts, include 4 parts of PI polymer substrate, 240 parts of NMP solvent, 7.5 parts of silica aerogel, 0.1 parts of low thermal conductivity graphite, 0.01 parts of PVDF binder, 0.01 parts of dimethylethanolamine dispersant, and 0.01 parts of polyoxyethylene alkyl ether (polyoxyethylene dodecyl ether) surfactant.

[0168] The silica aerogel has a thermal conductivity of 0.02 W / (m·K) and an average pore size of 1 μm; the low thermal conductivity graphite has a thermal conductivity of 10 W / (m·K) and an average pore size of 2 μm. The mass ratio of silica aerogel to low thermal conductivity graphite is calculated to be 0.15 W / (m·K) based on the desired total thermal conductivity of the mixture, resulting in a mass ratio of 75:1 for silica (0.02 W / (m·K)) to low thermal conductivity graphite (10 W / (m·K)).

[0169] The preparation steps are as follows:

[0170] S1.1 First, 8 parts of PI polymer substrate and methylpyrrolidone (NMP) solvent are mechanically stirred for 4 hours until fully dissolved to form a solution;

[0171] S1.2 Then, the fully ground silica aerogel, low thermal conductivity graphite, PVDF binder, dimethyl ethanolamine dispersant, and polyoxyethylene alkyl ether surfactant are added to the solution in S1.1 and mechanically stirred for 12 hours to form a uniform heat-insulating slurry with a certain viscosity.

[0172] S1.3 The heat insulation slurry was sequentially coated, dried, and cold-pressed to prepare a heat insulation film. The drying temperature was 60℃, the cold-pressing pressure was 2MPa, and the cold-pressing time was 120s. The thickness of the resulting heat insulation film is shown in Table 1.

[0173] (2) Preparation of battery cells.

[0174] The shell includes a shell body and a cover plate. The shell body includes a bottom plate and side plates connected to the bottom plate, which together form a receiving cavity. The shell body has an opening communicating with the receiving cavity, and the cover plate is placed over the opening to close the receiving cavity. The shell body is a rectangular aluminum shell body. The aforementioned heat insulation film is directly wrapped around the outer surface of the shell body (outer surface of the side plates), and then secured with tape at the segmented points after the heat insulation film is wrapped. Finally, a blue film (insulating film) with an adhesive layer is used to wrap all areas of the heat insulation film to fix it in place.

[0175] Positive electrode, negative electrode, and separator can be formed into an electrode assembly through winding or stacking processes. The electrode assembly is then encapsulated within a housing cavity. Electrolyte is immersed in the electrode assembly to obtain a single battery cell.

[0176] Examples 2-6

[0177] The raw material composition and preparation process are the same as those of the heat insulation film in Example 1. The difference is that at least one of the proportion of the raw material composition and the thickness of the heat insulation film is different, as shown in Table 1.

[0178] Comparative Example 1

[0179] The battery cell of Comparative Example 1 is basically the same as the battery cell of Example 1, except that its casing does not contain the heat insulation film of Example 1, and its outer side is wrapped with a blue film (insulating film) with an adhesive layer.

[0180] Comparative Example 2

[0181] The battery cell of Comparative Example 2 is basically the same as that of Example 1, except that the proportion of raw material components is different, as shown in Table 1.

[0182] Table 1

[0183]

[0184] The mass percentage of each component in the prepared heat insulation film is shown in Table 2 below.

[0185] Table 2

[0186]

[0187] Examples 7-8

[0188] The raw material composition, ratio and preparation process are the same as those of the heat insulation film in Example 2. The difference is that at least one of the average pore size of silica aerogel and the average pore size of low thermal conductivity graphite is different, as shown in Table 3.

[0189] Table 3

[0190]

[0191] The following are the performance testing methods.

[0192] (1) Test of thermal conductivity parameters at room temperature.

[0193] The heat insulation film sample prepared in the above embodiment was cut into 35mm*35mm pieces and stacked to a thickness of 1.2mm. The sample was placed in a room temperature thermal conductivity meter and tested according to GB / T 10295 standard. The thermal conductivity, thermal diffusivity and specific heat of the sample at room temperature (25ºC) were measured, as shown in Table 4.

[0194] Table 4

[0195]

[0196] As shown in Table 4, the thermal conductivity, thermal diffusivity and specific heat of the insulation films prepared in each embodiment are lower than those in Comparative Example 2, indicating that they have better insulation performance.

[0197] Compared to Example 5, controlling the heat-spreading filler content within the range of 0.1% to 1% in Examples 1-4 can reduce the estimated thermal conductivity λ. mix The difference between the thermal conductivity of the insulation film and the thermal conductivity of the heat insulation film makes the thermal conductivity of the insulation film closer to the estimated thermal conductivity λ. mix .

[0198] Compared to Example 6, the predicted thermal conductivity λ in Examples 1-4 is different. mix Within the range of 0.1 W / (m·K) to 0.5 W / (m·K), the estimated thermal conductivity λ can be reduced. mix The difference between the thermal conductivity of the insulation film and the thermal conductivity of the heat insulation film makes the thermal conductivity of the insulation film closer to the estimated thermal conductivity λ. mix .

[0199] As can be seen from Examples 2 and 7-8, a uniformly distributed smaller pore size is beneficial to obtaining a lower thermal conductivity.

[0200] (2) Temperature uniformity performance test.

[0201] The testing method is as follows: Figure 7 As shown, the battery cell prepared in the example or comparative example is taken as battery cell #1, and then a heating film 11 is added in the same battery cell preparation process to obtain battery cell #2 with a heating film 11 built into the center and other parts the same as battery cell #1.

[0202] Battery cells #1 and #2 are placed face-to-face and secured by clamp 12. A 4mm thick ceramic heat insulation pad 13 is placed in the area where the clamp 12 contacts the battery cells to prevent the battery cells from absorbing heat from the clamp 12. Temperature monitoring point A is set at the center of the face where battery cells #1 and #2 are face-to-face. Temperature monitoring point B is set 10mm above temperature monitoring point A, corresponding to the position 10mm below the explosion-proof valve. Temperature monitoring point C is set 10mm below temperature monitoring point A, from the bottom edge.

[0203] The test procedure is as follows: At room temperature (20℃~30℃), the bottom water cooling plate of the battery cell is turned on to perform natural convection water circulation. The water circulation flow rate is 2L / min. Then, the built-in heating film is turned on to trigger thermal runaway (the power of the heating film is 500W~600W). After the thermal runaway is triggered, the heating film immediately stops heating. The standard for thermal runaway is that the heating rate is ≥1℃ / s. At the same time, the forced cooling cycle is turned on to slowly cool it down. The temperature-time curves of temperature monitoring point A, temperature monitoring point B, and temperature monitoring point C and the heating time of the heating film are obtained, which are curves A, curve B, and curve C, respectively.

[0204] The test results for Comparative Example 1 and Example 1 are as follows: Figure 8 and Figure 9 Since temperature monitoring point C is closest to the bottom water-cooling plate, its temperature is the lowest, while temperature monitoring point A is closest to the heating film, so its temperature is the highest. When the heating film heats up to thermal runaway, the location with the largest temperature difference is the temperature difference between temperature monitoring points A and C.

[0205] The battery cell in Comparative Example 1 does not contain a heat insulation film inside its casing. Figure 8 It can be seen that the maximum temperature difference between temperature monitoring point A and temperature monitoring point C is ΔTmax = 254.6℃. The battery cell in Example 1 contains the aforementioned heat-insulating film inside its casing. Figure 9 It can be seen that the maximum temperature difference between temperature monitoring point A and temperature monitoring point C is ΔTmax = 204.6℃. The smaller ΔTmax is, the better the temperature uniformity of the shell. From... Figure 8 and Figure 9 It can be seen that the battery cell containing a heat-insulating film used in Embodiment 1 of this application can achieve good temperature uniformity and reduce heat concentration; in addition, from Figure 8 and Figure 9 It can be seen that the temperature at temperature monitoring point A in Example 1 is lower than the temperature at temperature monitoring point A in Comparative Example 1 at the same time point. This indicates that the use of a battery cell containing a heat insulation film in Example 1 can reduce the overall temperature of the battery cell to a lower level, and the heat insulation performance is good.

[0206] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0207] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A battery cell, characterized in that, The device includes a housing and an electrode assembly, wherein the electrode assembly is disposed within the housing, and the housing includes a housing body and a heat insulation film disposed on at least a portion of the outer surface of the housing body; the heat insulation film comprises, by mass parts, 3 to 12 parts of polymer, 5 to 30 parts of heat insulation filler and 0.01 to 1 part of heat homogenizing filler.

2. The battery cell as described in claim 1, characterized in that, The heat insulation film comprises, by weight, 3-12 parts of polymer, 7-15 parts of heat insulation filler, and 0.05-0.5 parts of heat homogenizing filler.

3. The battery cell as described in claim 1 or 2, characterized in that, The heat insulation film also includes one or more of the following: adhesive, dispersant, and surfactant.

4. The battery cell as described in claim 3, characterized in that, One or more of the following conditions must be met: (1) In the heat insulation film, when the polymer is 3 to 12 parts by mass, the adhesive is 0.01 to 0.5 parts; (2) When the polymer in the heat insulation film is 3 to 12 parts by mass, the dispersant is 0.01 to 0.5 parts; (3) When the polymer in the heat insulation film is 3 to 12 parts by mass, the surfactant is 0.01 to 0.3 parts; (4) The adhesive comprises one or more of polyvinylidene fluoride, polyvinyl alcohol, and polymethyl methacrylate; (5) The dispersant includes one or more of dimethylethanolamine, methylethanolamine, and polycarboxylic acid; (6) The surfactant includes polyoxyethylene alkyl ether.

5. The battery cell according to any one of claims 1 to 4, characterized in that, The thermal conductivity of the heat insulation film is 0.1 W / (m·K) to 0.6 W / (m·K).

6. The battery cell according to any one of claims 1 to 5, characterized in that, In the total mass of the insulating filler and the heat-settling filler, the mass contents of the insulating filler and the heat-settling filler are m1 and m2, respectively; the thermal conductivity of the insulating filler and the heat-settling filler are λ1 and λ2, respectively; the estimated thermal conductivity of the mixture of the insulating filler and the heat-settling filler is λ. mix ;λ mix =(λ1m 1+ λ2m2) / (m 1+ m2); λ mix It ranges from 0.1 W / (m·K) to 0.5 W / (m·K).

7. The battery cell according to any one of claims 1 to 6, characterized in that, One or more of the following conditions must be met: (1) λ1 is 0.01W / (m·K)~0.8W / (m·K), and can be selected as 0.01W / (m·K)~0.04W / (m·K); (2) λ2 is 1W / (m·K)~50W / (m·K), and can be selected as 1W / (m·K)~20W / (m·K).

8. The battery cell according to any one of claims 1 to 7, characterized in that, One or more of the following conditions must be met: (1) The polymer includes one or more of polyethylene terephthalate, polycarbonate, polyimide and acrylic copolymer; (2) The heat insulation filler includes one or more of alumina, boron nitride, antimony trioxide, titanium dioxide and silicon dioxide; (3) The heat-spreading filler includes one or more of metallic materials, alloy materials, and carbon materials; (4) The average pore size of the heat insulation filler is 50 nm to 5 μm, and can be selected as 50 nm to 2 μm; (5) The average pore size of the heat-equalizing filler is 1μm~10μm, and can be selected as 1μm~5μm.

9. The battery cell as described in claim 8, characterized in that, The metallic material includes one or more of copper particles, aluminum particles, gold particles, and silver particles; the alloy material includes copper-aluminum alloy particles; and the carbon material includes one or more of graphite, graphene, and carbon nanotubes.

10. The battery cell according to any one of claims 1 to 9, characterized in that, The thickness of the heat insulation film is 0.05mm to 0.8mm, and can be selected as 0.05mm to 0.2mm.

11. The battery cell according to any one of claims 1 to 10, characterized in that, One or more of the following conditions must be met: (1) The housing further includes a first insulating film, which is disposed between the housing body and the heat insulation film; (2) The housing further includes a second insulating film, which is disposed on the surface of the heat insulation film away from the housing body.

12. The battery cell according to any one of claims 1 to 11, characterized in that, The casing body includes two relatively large sidewalls that form the large surface of the battery cell, and the heat insulation film is disposed at least on the outer side of the two relatively large sidewalls.

13. A method for preparing a single battery cell, characterized in that, The step of preparing the shell includes the following steps: The polymer, 5-30 parts heat-insulating filler, and 0.01-1 parts heat-monopolizing filler, along with a solvent, are mixed in parts by weight to form a heat-insulating slurry. The shell is prepared by forming an insulating film on at least a portion of the outer surface of the shell body using the insulating slurry.

14. A casing for a battery cell, characterized in that, The shell includes a shell body and a heat insulation film disposed on at least a portion of the outer surface of the shell body; the heat insulation film comprises, by mass parts, 3 to 12 parts of polymer, 5 to 30 parts of heat insulation filler and 0.01 to 1 part of heat homogenizing filler; Alternatively, as defined in any one of claims 1 to 12.

15. A heat insulation film, characterized in that, The components of the heat insulation film, by mass parts, include 3 to 12 parts of polymer, 5 to 30 parts of heat insulation filler, and 0.01 to 1 part of heat homogenizing filler.

16. A battery, characterized in that, It includes one or more of the following: the battery cell according to any one of claims 1 to 12, the battery cell prepared by the method according to claim 13, the casing according to claim 14, and the heat insulation film according to claim 15.

17. An electrical device, characterized in that, It includes one or more of the following: the battery cell according to any one of claims 1 to 12, the battery cell prepared by the method according to claim 13, the casing according to claim 14, the heat insulation film according to claim 15, and the battery according to claim 16.

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