Case and preparation method therefor, battery, and electric device

Abstract

A case (100) and a preparation method therefor, a battery (5), and an electric device. The case (100) comprises a thermally conductive insulating layer (130). The thermally conductive insulating layer (130) is provided on at least part of the inner surface of the case (100). The thermal conductivity coefficient of the thermally conductive insulating layer (130) ranges from 0.03 W / mK to 10 W / mK, and the resistance of the thermally conductive insulating layer (130) at a high voltage of 1000 V ranges from 100 MΩ to 100 GΩ.

Description

Shell and preparation method thereof, battery and electrical equipment Technical Field

[0001] The present application relates to the field of batteries, and in particular to a shell and a preparation method thereof, a battery, and an electrical device. Background Art

[0002] Batteries are not only used in energy storage systems such as hydropower, thermal, wind, and solar power plants, but are also widely used in electric vehicles such as electric bicycles, electric motorcycles, and electric vehicles, as well as in a variety of fields such as military equipment and aerospace. With the increase in battery energy density and the reduction in manufacturing costs, people are also demanding higher charging speeds. On the one hand, the increase in charging speed is beneficial to market demand, but on the other hand, during fast charging, the greater the charging current, the more irreversible heat is generated within the battery. The electrode components are unable to dissipate heat in a timely manner, causing the battery surface temperature to rise and increasing the risk of thermal runaway.

[0003] Summary of the Invention

[0004] In view of the technical problems existing in the background technology, the present application provides a shell that can improve the heat dissipation effect of the shell and reduce the probability of thermal runaway of the battery.

[0005] A first aspect of the present application provides a shell, comprising a thermally conductive insulation layer, wherein the thermally conductive insulation layer is arranged on at least a portion of the inner surface of the shell, the thermal conductivity of the thermally conductive insulation layer is 0.03W / mK-10W / mK, and the resistance of the thermally conductive insulation layer under a high voltage of 1000V is 100MΩ-100GΩ.

[0006] The shell provided in the present application is provided with a thermally conductive insulating layer on at least part of the inner surface of the shell. By making the thermal conductivity coefficient and resistance of the thermally conductive insulating layer within the above-mentioned range, the thermal conductivity and insulation properties of the thermally conductive insulating layer can be improved at the same time. While reducing the risk of short circuit inside the shell, when the battery temperature rises during fast charging, the heat dissipation rate of the shell can be increased, the heat dissipation effect of the shell can be improved, the temperature of the battery surface can be reduced, and the probability of thermal runaway of the battery can be reduced.

[0007] According to some embodiments of the present application, the thermal conductivity of the thermally conductive insulating layer is 0.2W / mK-10W / mK, and the resistance of the thermally conductive insulating layer at a high voltage of 1000V is 500MΩ-50GΩ. This improves the thermal conductivity and insulation performance of the thermally conductive insulating layer, thereby enhancing the heat dissipation effect of the housing.

[0008] According to some embodiments of the present application, the leakage current of the thermally conductive insulation layer is 0-10 mA.

[0009] According to some embodiments of the present application, the leakage current of the thermally conductive insulation layer is 0.01 mA-1 mA.

[0010] Thus, by setting the leakage current of the thermally conductive insulating layer to be within the above range, the withstand voltage performance of the thermally conductive insulating layer is improved.

[0011] According to some embodiments of the present application, the thermally conductive insulating layer includes 1 to 50 parts by weight of a thermally conductive filler and 50 to 95 parts by weight of a prepolymer. Thus, by ensuring that the contents of the thermally conductive filler and prepolymer are within the aforementioned ranges, the insulation and thermal conductivity of the thermally conductive insulating layer can be improved, thereby enhancing the heat dissipation effect of the housing.

[0012] According to some embodiments of the present application, the content of the thermally conductive filler is 10 parts by weight to 30 parts by weight, and the content of the prepolymer is 70 parts by weight to 90 parts by weight, thereby improving the insulation and thermal conductivity of the thermally conductive insulation layer and the heat dissipation effect of the housing.

[0013] According to some embodiments of the present application, the thermally conductive filler includes one or more of inorganic particles having a dielectric constant greater than 5, and inorganic particles having ion conductivity but not storing ions. This improves the thermal conductivity of the thermally conductive insulating layer and enhances the heat dissipation effect of the housing.

[0014] According to some embodiments of the present application, the inorganic particles having a dielectric constant of 5 or more include boehmite, aluminum oxide, zinc oxide, silicon oxide, titanium oxide, zirconium oxide, barium oxide, calcium oxide, magnesium oxide, nickel oxide, tin oxide, cerium oxide, yttrium oxide, hafnium oxide, aluminum hydroxide, magnesium hydroxide, silicon carbide, boron carbide, aluminum nitride, silicon nitride, boron nitride, magnesium fluoride, calcium fluoride, barium fluoride, barium sulfate, magnesium aluminum silicate, lithium magnesium silicate, sodium magnesium silicate, bentonite, hectorite, zirconium titanate, barium titanate, Pb(Zr,Ti)O3, Pb 1-m La m Zr 1-n Ti n O3、Pb(Mg 1 / 3 Nb 2 / 3 )O3-PbTiO3, and one or more of their respective modified inorganic particles, 0<m<1, 0<n<1. Thus, the thermal conductivity of the thermally conductive insulating layer is improved, and the heat dissipation effect of the shell is improved.

[0015] According to some embodiments of the present application, the inorganic particles having ion conductivity but not storing ions include Li3PO4, lithium titanium phosphate Li x 1Ti y1 (PO4)3, lithium aluminum titanium phosphate Li x2 Al y2 Ti z1 (PO4)3, (LiAlTiP) x3 O y3 Type glass, lanthanum lithium titanate Lix4 La y4 TiO3, lithium germanium thiophosphate Li x5 Ge y5 P z2 S w , lithium nitride Li x6 N y6 、SiS2 type glass Li x7 Si y7 S z3 and P2S5 glass Li x8 P y8 S z4 One or more of the following: 0<x1<2, 0<y1<3, 0<x2<2, 0<y2<1, 0<z1<3, 0<x3<4, 0<y3<13, 0<x4<2, 0<y4<3, 0<x5<4, 0<y5<1, 0<z2<1, 0<w<5, 0<x6<4, 0<y6<2, 0<x7<3, 0<y7<2, 0<z3<4, 0<x8<3, 0<y8<3, 0<z4<7. Thus, the thermal conductivity of the thermally conductive insulating layer is improved, and the heat dissipation effect of the shell is improved.

[0016] According to some embodiments of the present application, the prepolymer includes one or more of polyimide, phenolic resin, urea-formaldehyde resin, or epoxy resin. Thus, the prepolymers of the above types can improve the insulation performance and electrolyte resistance of the thermally conductive insulating layer, and improve the stability of the thermally conductive insulating layer.

[0017] According to some embodiments of the present application, the thermally conductive insulating layer further comprises at least one of a dispersant and a curing agent, thereby improving the uniformity and curing rate of the thermally conductive insulating layer.

[0018] According to some embodiments of the present application, the dispersant includes one or more of sodium carboxymethyl cellulose, styrene-butadiene rubber, polyvinyl pyrrolidone, sodium lauryl sulfate, methyl amyl alcohol, polyacrylamide, or guar gum. This improves the uniformity of the thermally conductive insulating layer, thereby improving the insulation and thermal conductivity of the thermally conductive insulating layer and enhancing the heat dissipation effect of the housing.

[0019] According to some embodiments of the present application, the curing agent includes one or more of hexamethylenetetramine, ethylenediamine, hexamethylenediamine, diethylenetriamine, triethylenetetramine, p-phenylenediamine, m-phenylenediamine, terephthalic acid, terephthalic acid, maleic anhydride, or phthalic anhydride, thereby increasing the curing rate of the thermally conductive insulating layer.

[0020] According to some embodiments of the present application, the thickness of the thermally conductive insulating layer is 1 μm-1000 μm.

[0021] According to some embodiments of the present application, the thickness of the thermally conductive insulating layer is 20 μm-200 μm.

[0022] Therefore, by setting the thickness of the heat-conducting insulating layer within the above range, the heat-conducting insulating layer can be improved in terms of heat conductivity and insulation performance, thereby improving the heat dissipation effect of the housing.

[0023] According to some embodiments of the present application, the housing includes a bottom wall and side walls, the side walls being connected to the edges of the bottom wall, the bottom wall and the side walls forming a receiving cavity with an opening, and the thermally conductive insulating layer being provided on at least a portion of the inner surface of the side walls and the bottom wall. Thus, the housing can be used to accommodate the electrode assembly. When the temperature of the electrode assembly rises during fast charging, the thermally conductive insulating layer can improve the housing's ability to dissipate heat from the electrode assembly, reduce heat accumulation within the housing, and reduce the risk of thermal runaway in the battery.

[0024] According to some embodiments of the present application, the thermally conductive insulating layer is provided on the entire inner surface of the side wall and the entire inner surface of the bottom wall. As a result, when the temperature of the electrode assembly rises during fast charging, the thermally conductive insulating layer can improve the heat dissipation capability of the housing to the electrode assembly, reduce heat accumulation inside the housing, and reduce the risk of thermal runaway of the battery.

[0025] The second aspect of the present application provides a method for preparing a housing, comprising: forming a thermally conductive insulating layer on at least a portion of the inner surface of the housing, wherein the thermally conductive insulating layer has a thermal conductivity of 0.03W / mK-10W / mK, and the thermally conductive insulating layer has a resistance of 100MΩ-100GΩ under a high voltage of 1000V. The prepared housing thus has excellent insulation and thermal conductivity, which can improve the heat dissipation effect of the housing. When the battery temperature rises during fast charging, the heat can be quickly dissipated from the housing, thereby improving the heat dissipation capacity of the housing, reducing the temperature of the battery surface, and reducing the probability of thermal runaway of the battery.

[0026] According to some embodiments of the present application, the method includes: mixing 1 to 50 parts by weight of a thermally conductive filler, 50 to 95 parts by weight of a prepolymer, and a solvent into a slurry, and applying the slurry to at least a portion of the inner surface of the housing to form the thermally conductive insulating layer. This improves the thermal conductivity and insulating properties of the thermally conductive insulating layer, and enhances the electrolyte resistance of the thermally conductive insulating layer.

[0027] According to some embodiments of the present application, the method further comprises: adding at least one of a dispersant and a curing agent to the slurry to form the thermally conductive insulating layer, thereby improving the uniformity and curing ability of the thermally conductive insulating layer.

[0028] According to some embodiments of the present application, the method further includes: cleaning and activating the housing before forming the thermally conductive insulating layer, thereby improving the bonding strength between the thermally conductive insulating layer and the inner surface of the housing and reducing the risk of the thermally conductive insulating layer falling off.

[0029] The third aspect of the present application provides a battery, comprising the housing provided in the first aspect of the present application or the housing prepared by the method provided in the second aspect of the present application. Thus, the battery has excellent heat dissipation and can reduce the risk of thermal runaway of the battery.

[0030] According to some embodiments of the present application, the housing includes a bottom wall and side walls, the side walls being connected to the edges of the bottom wall, the bottom wall and the side walls forming a receiving cavity with an opening, the battery further including a positive electrode sheet, a negative electrode sheet, and a diaphragm, the positive electrode sheet, the negative electrode sheet, and the diaphragm being located within the receiving cavity, the positive electrode sheet including a positive electrode current collector, the negative electrode sheet including a negative electrode current collector, the orthographic projection of the diaphragm on the side wall being located within and not overlapping the orthographic projection of the negative electrode current collector on the side wall, or the orthographic projection of the diaphragm on the side wall being located within and not overlapping the orthographic projection of the positive electrode current collector on the side wall; the inner surface of the bottom wall is provided with the thermally conductive insulating layer, the thermally conductive insulating layer being in contact with the negative electrode current collector or the positive electrode current collector. Thus, while improving the heat dissipation effect of the housing, the risk of corrosion caused by contact between the negative electrode current collector or the positive electrode current collector and the housing is reduced.

[0031] According to some embodiments of the present application, the orthographic projection of the separator on the side wall is within the range of the orthographic projection of the negative electrode current collector on the side wall and does not overlap, thereby reducing the risk of corrosion caused by contact between the negative electrode current collector and the housing.

[0032] According to some embodiments of the present application, the negative electrode current collector includes a first region and a second region, wherein the orthographic projection of the first region on the sidewall coincides with the orthographic projection of the separator on the sidewall, and the orthographic projection of the second region on the sidewall is within the orthographic projection of the thermally conductive insulating layer on the sidewall. This reduces the risk of a short circuit caused by contact between the negative electrode current collector and the housing.

[0033] According to some embodiments of the present application, along the extension direction of the negative electrode current collector, the length of the second region is D, and satisfies 1 mm ≤ D ≤ 5 mm.

[0034] According to some embodiments of the present application, the end of the orthographic projection of the thermally conductive insulating layer on the side wall that is closer to the opening of the accommodating cavity overlaps with the end of the orthographic projection of the diaphragm on the side wall that is farther from the opening of the accommodating cavity, thereby reducing the risk of overlapping between the current collector and the housing.

[0035] According to some embodiments of the present application, along the extension direction of the negative electrode current collector, the height of the thermally conductive insulating layer on the side wall is H, and H is ≥ 5 mm. This reduces the risk of short circuit caused by contact between the negative electrode current collector and the housing.

[0036] According to some embodiments of the present application, 1 cm ≤ H ≤ 3 cm, thereby reducing the risk of short circuit caused by contact between the negative electrode current collector and the shell.

[0037] According to some embodiments of the present application, the battery includes: a top cover assembly, which is suitable for closing the opening of the accommodating cavity; the side walls are each provided with the thermally conductive insulation layer, and the thermally conductive insulation layer is spaced apart from one end of the top cover assembly close to the top cover assembly and one end of the top cover assembly close to the shell.

[0038] According to some embodiments of the present application, the distance L between the end of the thermally conductive insulating layer closest to the top cover assembly and the end of the top cover assembly closest to the housing is 2 mm ≤ L ≤ 5 mm. Thus, when the top of the housing is welded, the influence of the thermally conductive insulating layer on the welding is reduced.

[0039] A fourth aspect of the present application provides an electrical device comprising the battery provided in the third aspect of the present application, thereby enabling the electrical device to have excellent heat dissipation capabilities.

[0040] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become obvious from the description below, or will be learned through practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiment below. The accompanying drawings are for illustration purposes only and are not to be considered as limiting the present application. The same reference numerals are used throughout the drawings to represent the same components. In the drawings:

[0042] FIG1 is a schematic structural diagram of a housing according to an embodiment of the present application.

[0043] FIG2 is a schematic structural diagram of a housing according to another embodiment of the present application.

[0044] FIG3 is a schematic diagram of a positive electrode current collector, a negative electrode current collector, and a separator according to an embodiment of the present application.

[0045] FIG4 is a schematic structural diagram of a housing according to another embodiment of the present application.

[0046] FIG5 is an enlarged view of a local area of ​​FIG4.

[0047] FIG6 is a schematic structural diagram of a housing according to another embodiment of the present application.

[0048] FIG. 7 is a schematic diagram of a battery according to an embodiment of the present application.

[0049] FIG8 is an exploded view of the battery shown in FIG7 according to one embodiment of the present application.

[0050] FIG9 is a schematic diagram of a battery module according to an embodiment of the present application.

[0051] FIG10 is a schematic diagram of a battery pack according to an embodiment of the present application.

[0052] FIG. 11 is an exploded view of the battery pack shown in FIG. 10 according to an embodiment of the present application.

[0053] FIG12 is a schematic diagram of an electrical device using a battery as a power source according to an embodiment of the present application.

[0054] Explanation of the accompanying drawings: 100: shell; 101: bottom wall; 102: side wall; 110: cover plate; 120: lower plastic; 130: thermally conductive insulating layer; 200: electrode assembly; 210: negative electrode current collector; A: first area; B: second area; 220: positive electrode current collector; 230: diaphragm; 1: battery pack; 2: upper box; 3: lower box; 4: battery module; 5 battery. DETAILED DESCRIPTION

[0055] The following embodiments of the technical solution of the present application are described in detail. The following embodiments are only used to more clearly illustrate the technical solution of the present application and are therefore only used as examples and are not intended to limit the scope of protection of the present application.

[0056] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0057] For the sake of clarity, only some numerical ranges are specifically disclosed herein. However, any lower limit may be combined with any upper limit to form an unspecified range; and any lower limit may be combined with other lower limits to form an unspecified range, and similarly, any upper limit may be combined with any other upper limit to form an unspecified range. In addition, each individually disclosed point or single value may itself serve as a lower limit or upper limit and be combined with any other point or single value, or with other lower limits or upper limits, to form an unspecified range.

[0058] In the description of the embodiments of this application, the term "and / or" is simply a description of the association relationship between associated objects, indicating that three relationships can exist. For example, A and / or B can represent the following three situations: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this document generally indicates that the associated objects are in an "or" relationship.

[0059] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned figure descriptions are intended to cover non-exclusive inclusions.

[0060] Currently, market developments indicate that batteries are increasingly being used. They are not only used in energy storage systems such as hydropower, thermal, wind, and solar power plants, but are also widely used in electric vehicles like electric bicycles, electric motorcycles, and electric cars, as well as in military equipment and aerospace. As battery applications continue to expand, market demand is also growing.

[0061] The heat generated within the battery includes reversible chemical heat caused by entropy change and irreversible Joule heat. Joule heat is proportional to the square of the current. That is, during fast charging, the greater the charging current, the more irreversible heat is generated within the battery. Due to the long heat dissipation path within the battery, the battery cannot dissipate heat in a timely manner. When the temperature accumulates to a certain level, side reactions will occur within the battery, such as the decomposition of the solid electrolyte membrane (SEI membrane). Most side reactions within the battery are exothermic, which will lead to further heat accumulation and increase the risk of thermal runaway.

[0062] The shell proposed in this application is provided with a thermally conductive insulating layer on at least part of the inner surface of the shell. By making the thermal conductivity and resistance of the thermally conductive insulating layer within a certain range, the insulation performance and thermal conductivity of the thermally conductive insulating layer can be improved at the same time, thereby improving the heat dissipation effect of the shell and reducing the risk of thermal runaway of the battery.

[0063] The shell disclosed in the embodiment of the present application is suitable for lithium-ion batteries and sodium-ion batteries, and the battery disclosed in the embodiment of the present application can be used in electrical equipment that uses the battery as a power source or various energy storage systems that use the battery as an energy storage element. Electrical equipment may include but is not limited to mobile phones, tablets, laptops, electric toys, power tools, battery cars, electric cars, ships, spacecraft, etc. Among them, electric toys may include fixed or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc., and spacecraft may include airplanes, rockets, space shuttles, and spacecraft, etc.

[0064] In a first aspect, the present application provides a shell, comprising a thermally conductive insulation layer, wherein the thermally conductive insulation layer is arranged on at least a portion of the inner surface of the shell, the thermal conductivity of the thermally conductive insulation layer is 0.03W / mK-10W / mK, and the resistance of the thermally conductive insulation layer under a high voltage of 1000V is 100MΩ-100GΩ.

[0065] The shell provided in the present application is provided with a thermally conductive insulating layer on at least part of the inner surface of the shell. By ensuring that the thermal conductivity and resistance of the thermally conductive insulating layer are within the above-mentioned ranges, the thermal conductivity and insulation properties of the thermally conductive insulating layer can be simultaneously improved. While preventing short circuits inside the shell, the rate at which heat is transferred from the inside of the shell to the outside of the shell is increased, thereby improving the heat dissipation effect of the shell, reducing heat accumulation inside the shell, lowering the temperature of the battery surface, and reducing the probability of thermal runaway of the battery.

[0066] According to some embodiments of the present application, the thermal conductivity of the thermally conductive insulating layer is 0.03W / mK-10W / mK, for example, it can be 0.03W / mK, 1W / mK, 2W / mK, 3W / mK, 4W / mK, 5W / mK, 6W / mK, 7W / mK, 8W / mK, 9W / mK or 10W / mK, etc., or it can be a range composed of any of the above values. Thus, the thermal conductivity of the thermally conductive insulating layer is improved, and the heat inside the shell is quickly transferred to the outside of the shell, thereby improving the heat dissipation effect of the shell, reducing the accumulation of heat inside the shell, and reducing the risk of thermal runaway of the battery. According to some specific embodiments of the present application, the thermal conductivity of the thermally conductive insulating layer is 0.2W / mK-10W / mK.

[0067] In this application, the thermal conductivity of the thermally conductive insulating layer is tested according to the GB / T10295-2008 test standard.

[0068] According to some embodiments of the present application, the resistance of the thermally conductive insulating layer under a high voltage of 1000V is 100MΩ-100GΩ, for example, it can be 100MΩ, 500MΩ, 1GΩ, 10GΩ, 20GΩ, 30GΩ, 40GΩ, 50GΩ, 60GΩ, 70GΩ, 80GΩ, 90GΩ or 100GΩ, etc., or it can be a range composed of any of the above numerical values. Thus, the insulation performance of the thermally conductive insulating layer is improved and the risk of short circuit in the shell is reduced. According to some specific embodiments of the present application, the resistance of the thermally conductive insulating layer under a high voltage of 1000V can be 500MΩ-50GΩ.

[0069] In this application, the test method for the resistance of the thermally conductive insulation layer under a high voltage of 1000V is as follows: using a withstand voltage tester, the negative pole of the withstand voltage tester is connected to the side of the shell where the thermally conductive insulation layer is not provided, and the positive pole of the withstand voltage tester is connected to the thermally conductive insulation layer on the shell. The test is performed in accordance with GB / T 1408.2-2016, and the resistance value is read.

[0070] According to some embodiments of the present application, the leakage current of the thermally conductive insulation layer can be 0-10 mA, for example, 0, 1 mA, 2 mA, 3 mA, 4 mA, 5 mA, 6 mA, 7 mA, 8 mA, 9 mA, or 10 mA, or a range of any of the above values. This improves the thermal conductivity and insulation performance of the thermally conductive insulation layer while also improving its withstand voltage. According to some specific embodiments of the present application, the leakage current of the thermally conductive insulation layer can be 0.01 mA-1 mA.

[0071] In this application, the leakage current of the thermally conductive insulation layer is tested in accordance with GB / T 1408.2-2016.

[0072] According to some embodiments of the present application, the thermally conductive insulating layer may include 1 to 50 parts by weight of a thermally conductive filler and 50 to 95 parts by weight of a prepolymer. Thus, by ensuring that the contents of the thermally conductive filler and prepolymer in the thermally conductive insulating layer are within the above ranges, the thermal conductivity and insulation performance of the thermally conductive insulating layer are improved.

[0073] According to some embodiments of the present application, the thermally conductive insulating layer may include 1 to 50 parts by weight of a thermally conductive filler, for example, 1 part by weight, 5 parts by weight, 10 parts by weight, 15 parts by weight, 20 parts by weight, 25 parts by weight, 30 parts by weight, 35 parts by weight, 40 parts by weight, 45 parts by weight, or 50 parts by weight, or the like, or may be a range consisting of any of the above numerical values. According to some specific embodiments of the present application, the thermally conductive insulating layer may include 10 to 30 parts by weight of a thermally conductive filler. Thus, by making the content of the thermally conductive filler within the above range, while improving the thermal conductivity of the thermally conductive insulating layer, the brittleness of the thermally conductive insulating layer is reduced, the mechanical strength and density of the thermally conductive insulating layer are improved, and the stability of the thermally conductive insulating layer is improved.

[0074] According to some embodiments of the present application, the thermally conductive insulating layer may include 50-95 parts by weight of prepolymer, for example, 50 parts by weight, 55 parts by weight, 60 parts by weight, 65 parts by weight, 70 parts by weight, 75 parts by weight, 80 parts by weight, 85 parts by weight, 90 parts by weight, or 95 parts by weight, or may be a range consisting of any of the above values. According to some specific embodiments of the present application, the thermally conductive insulating layer may include 70-90 parts by weight of prepolymer. Thus, by making the content of the prepolymer within the above range, while improving the insulation performance of the thermally conductive insulating layer, the electrolyte resistance of the thermally conductive insulating layer is improved, the risk of the thermally conductive insulating layer falling off due to long-term immersion in the electrolyte is reduced, and the influence of the prepolymer on the thermal conductivity of the thermally conductive insulating layer is reduced.

[0075] According to some embodiments of the present application, the volume average particle size D of the thermally conductive filler is v 50 can be 50nm-2000nm, for example, it can be 50nm, 100nm, 500nm, 1000nm, 1500nm or 2000nm, or it can be a range composed of any of the above values. In this way, the uniformity of the thermally conductive filler in the thermally conductive insulation layer is improved, the overall thermal conductivity of the thermally conductive insulation layer is improved, the heat dissipation effect of the shell is improved, the temperature of the shell surface is reduced, and the risk of thermal runaway of the battery is reduced. According to some specific embodiments of the present application, the volume average particle size D of the thermally conductive filler is v 50 can be 100nm-1000nm.

[0076] In this application, the volume average particle size D v50 refers to the particle size corresponding to the cumulative volume distribution percentage reaching 50%, as measured, for example, using a laser particle size analyzer (Malvern Master Size 2000) in accordance with the standard GB / T 19077-2016 / ISO 13320:2009. The specific testing procedure is as follows: Take an appropriate amount of the sample to be tested (ensure the sample concentration is 8%-12% obscuration), add 20ml of deionized water, and ultrasonicate for 5 minutes (53kHz / 120W) to ensure complete dispersion of the sample. The sample is then measured according to the GB / T 19077-2016 / ISO 13320:2009 standard.

[0077] According to some embodiments of the present application, the thermally conductive filler includes one or more of inorganic particles having a dielectric constant greater than 5, and inorganic particles having ion conductivity but not storing ions. This improves the thermal conductivity of the thermally conductive insulating layer and enhances the heat dissipation effect of the housing.

[0078] According to some embodiments of the present application, the inorganic particles having a dielectric constant of 5 or more include boehmite, aluminum oxide, zinc oxide, silicon oxide, titanium oxide, zirconium oxide, barium oxide, calcium oxide, magnesium oxide, nickel oxide, tin oxide, cerium oxide, yttrium oxide, hafnium oxide, aluminum hydroxide, magnesium hydroxide, silicon carbide, boron carbide, aluminum nitride, silicon nitride, boron nitride, magnesium fluoride, calcium fluoride, barium fluoride, barium sulfate, magnesium aluminum silicate, lithium magnesium silicate, sodium magnesium silicate, bentonite, hectorite, zirconium titanate, barium titanate, Pb(Zr,Ti)O3, Pb 1-m La m Zr 1-n Ti n O3、Pb(Mg 1 / 3 Nb 2 / 3 )O3-PbTiO3, and one or more of their respective modified inorganic particles, 0<m<1, 0<n<1. Thus, the thermal conductivity of the thermally conductive insulating layer is improved, and the heat dissipation effect of the shell is improved.

[0079] According to some embodiments of the present application, the inorganic particles having ion conductivity but not storing ions include Li3PO4, lithium titanium phosphate Li x 1Ti y1 (PO4)3, lithium aluminum titanium phosphate Li x2 Al y2 Ti z1 (PO4)3, (LiAlTiP) x3 O y3 Type glass, lanthanum lithium titanate Li x4 La y4 TiO3, lithium germanium thiophosphate Li x5 Ge y5 P z2 Sw , lithium nitride Li x6 N y6 、SiS2 type glass Li x7 Si y7 S z3 and P2S5 glass Li x8 P y8 S z4 One or more of the following: 0<x1<2, 0<y1<3, 0<x2<2, 0<y2<1, 0<z1<3, 0<x3<4, 0<y3<13, 0<x4<2, 0<y4<3, 0<x5<4, 0<y5<1, 0<z2<1, 0<w<5, 0<x6<4, 0<y6<2, 0<x7<3, 0<y7<2, 0<z3<4, 0<x8<3, 0<y8<3, 0<z4<7. Thus, the thermal conductivity of the thermally conductive insulating layer is improved, and the heat dissipation effect of the shell is improved.

[0080] According to some embodiments of the present application, the weight average molecular weight of the prepolymer can be 500-10000, for example, 500, 1000, 2000, 3000, 4000, 5000, 6000, 7000, 8000, 9000 or 10000, or a range consisting of any of the above values. Thus, the brittleness of the polymer is reduced. According to some specific embodiments of the present application, the weight average molecular weight of the prepolymer can be 1000-5000.

[0081] According to some embodiments of the present application, the prepolymer may include one or more of polyimide, phenolic resin, urea-formaldehyde resin, or epoxy resin. Thus, the prepolymers of the above types can improve the insulation performance of the thermally conductive insulating layer and reduce the risk of short circuits in the housing.

[0082] According to some embodiments of the present application, the thermally conductive insulating layer may further include a dispersant, and the content of the dispersant may be 0.1 parts by weight to 10 parts by weight, for example, 0.1 parts by weight, 1 part by weight, 2 parts by weight, 3 parts by weight, 4 parts by weight, 5 parts by weight, 6 parts by weight, 7 parts by weight, 8 parts by weight, 9 parts by weight, or 10 parts by weight, or may be within a range consisting of any of the above values. Thus, the uniformity of the thermally conductive filler in the prepolymer is improved and the probability of agglomeration of the thermally conductive filler in the prepolymer is reduced. According to some specific embodiments of the present application, the content of the dispersant may be 0.5 parts by weight to 5 parts by weight.

[0083] According to some embodiments of the present application, the dispersant may include one or more of sodium carboxymethyl cellulose, styrene-butadiene rubber, polyvinyl pyrrolidone, sodium lauryl sulfate, methyl amyl alcohol, polyacrylamide, or guar gum. Thus, the above-mentioned dispersants can improve the uniformity of the dispersion of the thermally conductive filler in the prepolymer and reduce the probability of the thermally conductive filler agglomerating in the prepolymer.

[0084] According to some embodiments of the present application, the thermally conductive insulating layer may further include a curing agent, and the content of the curing agent may be 1 part by weight to 20 parts by weight, for example, 1 part by weight, 3 parts by weight, 5 parts by weight, 7 parts by weight, 9 parts by weight, 11 parts by weight, 13 parts by weight, 15 parts by weight, 17 parts by weight, or 20 parts by weight, or may be within a range consisting of any of the above values. Thus, the efficiency of curing the thermally conductive insulating layer on the housing is improved. According to some specific embodiments of the present application, the content of the curing agent may be 5 parts by weight to 10 parts by weight.

[0085] According to some embodiments of the present application, the curing agent may include one or more of hexamethylenetetramine, ethylenediamine, hexamethylenediamine, diethylenetriamine, triethylenetetramine, p-phenylenediamine, m-phenylenediamine, terephthalic acid, terephthalic acid, maleic anhydride, or phthalic anhydride. Thus, adding the above-mentioned curing agents to the thermally conductive insulating layer can improve the curing efficiency of the thermally conductive insulating layer.

[0086] According to some specific embodiments of the present application, the thermally conductive insulating layer includes 1-50 parts by weight of a thermally conductive filler, 50-95 parts by weight of a prepolymer, 0.1-10 parts by weight of a dispersant, and 1-20 parts by weight of a curing agent. This improves the thermal conductivity and insulation performance of the thermally conductive insulating layer while reducing the probability of thermally conductive filler agglomeration in the prepolymer, thereby improving the curing efficiency of the thermally conductive insulating layer.

[0087] According to some specific embodiments of the present application, the thickness of the thermally conductive insulating layer may be 1 μm-1000 μm, for example, 1 μm, 10 μm, 100 μm, 200 μm, 300 μm, 400 μm, 500 μm, 600 μm, 700 μm, 800 μm, 900 μm or 1000 μm, or a range consisting of any of the above values. Thus, while improving the thermal conductivity and insulation performance of the thermally conductive insulating layer, the space of the shell occupied by the thermally conductive insulating layer is reduced, thereby increasing the energy density of the battery. According to some specific embodiments of the present application, the thickness of the thermally conductive insulating layer may be 20 μm-200 μm.

[0088] The thickness of the thermally conductive insulating layer in this application is tested according to ISO 2360 standard.

[0089] According to some embodiments of the present application, referring to FIG1 , the housing 100 may include a bottom wall 101 and a side wall 102. The side wall 102 is connected to the edge of the bottom wall 101. The bottom wall 101 and the side wall 102 form a receiving cavity with an opening. The thermally conductive insulating layer 130 is provided on a portion of the inner surface of the side wall 102 and the bottom wall 101. This improves the heat dissipation effect of the housing 100, reduces the surface temperature of the housing 100, and reduces the risk of thermal runaway of the battery.

[0090] According to some embodiments of the present application, the thermally conductive insulating layer is provided on the entire inner surface of the side walls and the entire inner surface of the bottom wall. As a result, when the battery temperature rises, heat can be quickly dissipated from the housing 100, improving the heat dissipation capacity of the housing 100, lowering the battery surface temperature and reducing the probability of thermal runaway.

[0091] The second aspect of the present application provides a method for preparing a shell, comprising: forming a thermally conductive insulating layer on at least a portion of the inner surface of the shell, wherein the thermal conductivity of the thermally conductive insulating layer is 0.03W / mK-10W / mK, and the resistance of the thermally conductive insulating layer under a high voltage of 1000V is 100MΩ-100GΩ. Thus, the prepared shell 100 has excellent insulation and thermal conductivity, which can improve the heat dissipation effect of the shell 100. When the battery temperature rises during fast charging, the heat can be quickly dissipated from the shell 100, thereby improving the heat dissipation capacity of the shell 100, reducing the temperature of the battery surface, and reducing the probability of thermal runaway of the battery.

[0092] According to some embodiments of the present application, the thermally conductive insulating layer may be formed by single-layer coating or multi-layer coating.

[0093] According to some embodiments of the present application, the thermally conductive insulating layer may be formed by one or more of spray coating, dip coating, flow coating, or blade coating.

[0094] According to some embodiments of the present application, the method includes: mixing 1 to 50 parts by weight of a thermally conductive filler, 50 to 95 parts by weight of a prepolymer, and a solvent to form a slurry, and applying the slurry to the housing to form the thermally conductive insulating layer. This improves the insulation and thermal conductivity of the thermally conductive insulating layer, thereby enhancing the heat dissipation effect of the housing.

[0095] According to some embodiments of the present application, the content of the solvent in the slurry can be 30 parts by weight to 90 parts by weight, for example, 30 parts by weight, 40 parts by weight, 50 parts by weight, 60 parts by weight, 70 parts by weight, 80 parts by weight, or 90 parts by weight, or a range of any of the above values. This improves the uniformity of the slurry, improves the overall thermal conductivity and insulation performance of the thermally conductive insulating layer, improves the electrolyte resistance of the thermally conductive insulating layer, reduces the probability of the thermally conductive insulating layer falling off, reduces the risk of thermal runaway of the battery, and increases the service life of the battery.

[0096] According to some embodiments of the present application, the method further comprises: adding at least one of a dispersant and a curing agent to the slurry to form the thermally conductive insulating layer, thereby improving the uniformity and curing ability of the thermally conductive insulating layer.

[0097] According to some embodiments of the present application, the method includes: mixing 1 to 50 parts by weight of a thermally conductive filler, 50 to 95 parts by weight of a prepolymer, 0.1 to 10 parts by weight of a dispersant, 5 to 10 parts by weight of a curing agent, and a solvent to form a slurry; and applying the slurry to the housing to form the thermally conductive insulating layer. This improves the insulation and thermal conductivity of the thermally conductive insulating layer, thereby enhancing the heat dissipation effect of the housing.

[0098] According to some embodiments of the present application, the solvent may include one or more of water, methanol, ethanol, n-butanol, acetone, and N-methylpyrrolidone.

[0099] According to some embodiments of the present application, the slurry can form the thermally conductive insulating layer by thermal curing, and the thermal curing temperature can be 100°C-200°C, for example, it can be 100°C, 120°C, 140°C, 160°C, 180°C or 200°C, etc., or it can be a range consisting of any of the above numerical values.

[0100] According to some embodiments of the present application, the method further includes: cleaning and activating the shell before forming the thermally conductive insulating layer. Specifically, the shell surface can be cleaned and activated by one or more of plasma surface cleaning, acid cleaning, or alkaline cleaning to remove oil stains and impurities, so that the shell surface is enriched with active groups such as -OH and -COOH. These active groups can react with active groups such as -OH, -COOH, -NH2, and -C2H4O in the thermally conductive insulating layer slurry, thereby bonding the thermally conductive insulating layer to the shell surface through covalent bonds, thereby improving the bonding strength between the thermally conductive insulating layer and the shell and reducing the risk of the thermally conductive insulating layer falling off when immersed in high temperature or electrolyte for a long time.

[0101] The third aspect of the present application provides a battery comprising the housing provided in the first aspect of the present application or the housing prepared by the method provided in the second aspect of the present application. This improves the heat dissipation effect of the battery housing, reduces the temperature of the battery surface, and reduces the risk of thermal runaway in the battery.

[0102] According to some embodiments of the present application, referring to Figures 2 and 3, the housing 100 includes a bottom wall 101 and a side wall 102, the side wall 102 is connected to the edge of the bottom wall 101, and the bottom wall 101 and the side wall 102 form a receiving cavity with an opening. The battery 5 also includes a positive electrode sheet, a negative electrode sheet and a separator 230. The positive electrode sheet, the negative electrode sheet and the separator 230 are located in the receiving cavity. The positive electrode sheet includes a positive electrode collector 220, and the negative electrode sheet includes a negative electrode collector. The body 210, the orthographic projection of the diaphragm 230 on the side wall 102 is located within the range of the orthographic projection of the negative electrode current collector 210 on the side wall 102 and do not overlap, or the orthographic projection of the diaphragm 230 on the side wall 102 is located within the range of the orthographic projection of the positive electrode current collector 220 on the side wall 102 and do not overlap; the inner surface of the bottom wall 101 is provided with the thermally conductive insulating layer 130, and the thermally conductive insulating layer 130 is in contact with the negative electrode current collector 210 or the positive electrode current collector 220. Specifically, an insulating film (not shown) is provided on the outer surface of the electrode assembly 200 to insulate the electrode assembly 200 from the housing 100. A thermally conductive insulating layer 130 is provided between the negative electrode current collector 210 and the bottom wall 101 and side wall 102 of the housing 100. Heat generated inside the battery 5 can be directly dissipated to the outside of the battery 5 through the negative electrode current collector 210, the thermally conductive insulating layer 130, and the bottom wall 101 of the housing. This improves the heat dissipation effect of the housing 100 while reducing the risk of corrosion caused by contact between the negative electrode current collector 210 and the bottom wall 101 of the housing 100. Alternatively, a thermally conductive insulating layer 130 is provided between the positive electrode current collector 220 and the bottom wall 101 and side wall 102 of the housing 100. As a result, heat generated inside the battery 5 can be directly dissipated to the outside of the battery 5 through the positive electrode current collector 220, the thermally conductive insulating layer 130, and the bottom wall 101 of the housing, improving the heat dissipation effect of the housing 100.

[0103] According to some embodiments of the present application, the orthographic projection of the separator 230 on the side wall is located within the range of the orthographic projection of the negative electrode current collector 210 on the side wall and does not overlap.

[0104] According to some embodiments of the present application, referring to Figure 4, when the inner surface of the side wall 102 of the shell 100 is provided with the thermally conductive insulating layer 130, the thermally conductive insulating layer 130 can insulate the electrode assembly 200 from the shell 100, and there is no need to provide an insulating film on the outer surface of the electrode assembly 200, thereby reducing the volume occupied by the electrode assembly 200 and improving the energy density of the battery 5.

[0105] According to some embodiments of the present application, referring to FIG3 , the negative electrode current collector 210 includes a first region A and a second region B. The orthographic projection of the first region A on the sidewall 102 coincides with the orthographic projection of the separator on the sidewall 102, and the orthographic projection of the second region B on the sidewall 102 lies within the orthographic projection of the thermally conductive insulating layer 130 on the sidewall 102. Specifically, the first region A of the negative electrode current collector 210 can be the same size as the separator, while the second region B of the negative electrode current collector 210 extends toward the bottom wall 101 of the housing 100. The thermally conductive insulating layer 130 is disposed between the second region B and the bottom wall 101 of the housing 100. As a result, heat generated within the battery 5 can be directly dissipated to the exterior of the battery 5 through the negative electrode current collector 210, the thermally conductive insulating layer 130, and the bottom wall 101 of the housing. This improves the heat dissipation efficiency of the housing 100 while reducing the risk of corrosion caused by contact between the negative electrode current collector 210 and the bottom wall 101 of the housing 100.

[0106] According to some embodiments of the present application, referring to FIG3 , along the extension direction of the negative electrode current collector 210 , the length of the second region B is D, and satisfies 1 mm ≤ D ≤ 5 mm. For example, it can be 1 mm, 2 mm, 3 mm, 4 mm, or 5 mm, or can be a range consisting of any of the above values.

[0107] According to some embodiments of the present application, the end of the orthographic projection of the thermally conductive insulating layer 130 on the side wall 102 that is closer to the opening of the accommodating cavity overlaps with the end of the orthographic projection of the diaphragm 230 on the side wall that is farther from the opening of the accommodating cavity. This reduces the risk of overlapping of the current collector and the housing.

[0108] According to some embodiments of the present application, with reference to FIG2 , along the extension direction of the negative electrode current collector 210 , the height of the thermally conductive insulating layer 130 on the side wall 102 is H, where H ≥ 5 mm. For example, it can be 5 mm, 10 mm, 15 mm, 20 mm, 25 mm, 30 mm, 35 mm, or 40 mm, or can be a range of any of the above values. Thus, while improving the heat dissipation effect, it also increases the content of active material on the negative electrode sheet, thereby increasing the energy density of the battery 5. According to some specific embodiments of the present application, 1 cm ≤ H ≤ 3 cm.

[0109] According to some embodiments of the present application, the battery includes: a top cover assembly adapted to seal the opening of the accommodating cavity; and a thermally conductive insulating layer 130 provided on each of the side walls 102. The thermally conductive insulating layer 130 is spaced apart from an end of the thermally conductive insulating layer 130 proximal to the top cover assembly and an end of the thermally conductive insulating layer 130 proximal to the housing 100. This reduces the effect of the thermally conductive insulating layer 130 on welding the housing 100 and the top cover assembly.

[0110] According to some embodiments of the present application, referring to Figures 4-6, the distance L between the end of the thermally conductive insulating layer 130 near the top cover assembly and the end of the top cover assembly near the housing 100 is 2mm≤L≤5mm. For example, L can be 2.5mm, 3mm, 3.5mm, 4mm, 4.5mm, or 5mm, or can be a range of any of the above values. Specifically, when the top of the housing 100 is provided with the lower plastic 120 and the cover plate 110, by setting the value of L within the above range, the impact of the thermally conductive insulating layer 130 on the welding process can be reduced when the housing 100 and the top cover assembly are welded.

[0111] [Positive electrode]

[0112] The positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer disposed on at least one surface of the positive electrode current collector.

[0113] As an example, the positive electrode current collector has two surfaces facing each other in its thickness direction, and the positive electrode active material layer is provided on either or both of the two facing surfaces of the positive electrode current collector.

[0114] In some embodiments, the positive electrode current collector may be a metal foil or a composite current collector. For example, aluminum foil may be used as the metal foil. The composite current collector may include a polymer material base and a metal layer formed on at least one surface of the polymer material base. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0115] In some embodiments, when the battery is a lithium-ion battery, the positive electrode active material may adopt the positive electrode active material for lithium-ion batteries known in the art. As an example, the positive electrode active material may include one or more of the following materials: lithium-containing phosphates with an olivine structure, lithium transition metal oxides and their respective modified compounds. However, the present application is not limited to these materials, and other traditional materials that can be used as battery positive electrode active materials may also be used. These positive electrode active materials may be used alone or in combination of two or more. Examples of lithium transition metal oxides may include, but are not limited to, lithium cobalt oxide (such as LiCoO2), lithium nickel oxide (such as LiNiO2), lithium manganese oxide (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (also referred to as NCM333 ), LiNi 0.5 Co 0.2 Mn 0.3 O2 (also referred to as NCM 523 ), LiNi 0.5 Co 0.25 Mn 0.25 O2 (also referred to as NCM 211 ), LiNi 0.6 Co 0.2 Mn 0.2 O2 (also referred to as NCM 622 ), LiNi 0.8 Co 0.1 Mn 0.1 O2 (also referred to as NCM 811 ), lithium nickel cobalt aluminum oxide (such as LiNi 0.8 Co 0.15 Al 0.05 O2) and its modified compounds, etc. Examples of olivine-structured lithium-containing phosphates may include, but are not limited to, one or more of lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO4), a composite material of lithium manganese phosphate and carbon, lithium iron manganese phosphate, and a composite material of lithium iron manganese phosphate and carbon.

[0116] For example, when the battery is a sodium ion battery, as an example, the positive electrode active material may include, but is not limited to, at least one of a layered transition metal oxide, a polyanion compound, and a Prussian blue analog.

[0117] Examples of the layered transition metal oxides include:

[0118] Na 1-x Cu h Fe k Mn l M 1 m O 2-y , where M 1 One or more of Li, Be, B, Mg, Al, K, Ca, Ti, Co, Ni, Zn, Ga, Sr, Y, Nb, Mo, In, Sn and Ba, 0 <x≤0.33,0<h≤0.24,0≤k≤0.32,0<l≤0.68,0≤m<0.1,h+k+l+m=1,0≤y<0.2;

[0119] Na 0.67 Mn 0.7 Ni z M 20.3-z O2, where M 2 is one or more of Li, Mg, Al, Ca, Ti, Fe, Cu, Zn, and Ba, and 0 < z ≤ 0.1;

[0120] Na a Li b Ni c Mn d Fe e O2, where 0.67 < a ≤ 1, 0 < b < 0.2, 0 < c < 0.3, 0.67 < d + e < 0.8, and b + c + d + e = 1.

[0121] As an example of the above polyanionic compound, for example, the following can be listed:

[0122] A 1 f M 3 g (PO4) i O j X 1 3-j , where A 1 is one or more of H, Li, Na, K, and NH4, M 3 is one or more of Ti, Cr, Mn, Fe, Co, Ni, V, Cu, and Zn, X 1 is one or more of F, Cl, and Br, 0 < f ≤ 4, 0 < g ≤ 2, 1 ≤ i ≤ 3, and 0 ≤ j ≤ 2;

[0123] Na n M 4 PO4X 2 , where M 4 is one or more of Mn, Fe, Co, Ni, Cu, and Zn, X 2 is one or more of F, Cl, and Br, and 0 < n ≤ 2;

[0124] Na p M 5 q (SO4)3, where M 5 is one or more of Mn, Fe, Co, Ni, Cu, and Zn, 0 < p ≤ 2, and 0 < q ≤ 2;

[0125] Na s Mn t Fe 3-t (PO4)2(P2O7), where 0 < s ≤ 4, 0 ≤ t ≤ 3, for example, t is 0, 1, 1.5, 2, or 3.

[0126] As an example of the above Prussian blue analog, for example, the following can be listed:

[0127] A u M 6 v [M 7 (CN)6] w ·xH2O, where A is H + 、NH4 + 、one or more of alkali metal cations and alkaline earth metal cations, M 6 and M 7 are each independently one or more of transition metal cations, 0 < u ≤ 2, 0 < v ≤ 1, 0 < w ≤ 1, 0 < x < 6. For example, A is H + 、Li + 、Na + 、K + 、NH4 + 、Rb + 、Cs + 、Fr + 、Be 2+ 、Mg 2+ 、Ca 2+ 、Sr 2+ 、Ba 2+ and Ra 2+ one or more of, M 6 and M 7 are each independently cations of one or more transition metal elements selected from Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Sn, and W.

[0128] The modified compounds of the above materials can be doping modification and / or surface coating modification of the materials.

[0129] In some embodiments, the positive electrode active material layer may further optionally include a binder. As an example, the binder may include one or more of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride - tetrafluoroethylene - propylene terpolymer, vinylidene fluoride - hexafluoropropylene - tetrafluoroethylene terpolymer, tetrafluoroethylene - hexafluoropropylene copolymer, and fluorinated acrylate resin.

[0130] In some embodiments, the positive electrode active material layer may further optionally include a conductive agent. As an example, the conductive agent may include one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0131] In some embodiments, the positive electrode sheet can be prepared by the following method: the components for preparing the positive electrode sheet, such as the positive electrode active material, the conductive agent, the binder and any other components, are dispersed in a solvent (such as N-methylpyrrolidone) to form a positive electrode slurry; the positive electrode slurry is coated on the positive electrode current collector, and after drying, cold pressing and other processes, the positive electrode sheet can be obtained.

[0132] [Negative electrode]

[0133] The negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer disposed on at least one surface of the negative electrode current collector, wherein the negative electrode active material layer includes a negative electrode active material.

[0134] As an example, the negative electrode current collector has two surfaces facing each other in its thickness direction, and the negative electrode active material layer is provided on either or both of the two facing surfaces of the negative electrode current collector.

[0135] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. For example, copper foil may be used as the metal foil. The composite current collector may include a polymer base layer and a metal layer formed on at least one surface of the polymer base material. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymer base material (such as a base material of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0136] In some embodiments, the negative electrode active material may adopt the negative electrode active material for batteries known in the art. As an example, the negative electrode active material may include one or more of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials and lithium titanate, etc. The silicon-based material may be selected from one or more of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites and silicon alloys. The tin-based material may be selected from one or more of elemental tin, tin oxide compounds and tin alloys. However, the present application is not limited to these materials, and other traditional materials that can be used as negative electrode active materials for batteries may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0137] In some embodiments, the negative electrode active material layer may further include a binder. The binder may be selected from one or more of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0138] In some embodiments, the negative electrode active material layer may further include a conductive agent, which may be selected from one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0139] In some embodiments, the negative electrode active material layer may further optionally include other additives, such as a thickener (eg, sodium carboxymethyl cellulose (CMC-Na)).

[0140] In some embodiments, the negative electrode sheet can be prepared by the following method: the components for preparing the negative electrode sheet, such as the negative electrode active material, the conductive agent, the binder and any other components, are dispersed in a solvent (such as deionized water) to form a negative electrode slurry; the negative electrode slurry is coated on the negative electrode current collector, and after drying, cold pressing and other processes, the negative electrode sheet can be obtained.

[0141] [Electrolytes]

[0142] The electrolyte plays the role of conducting ions between the positive electrode and the negative electrode. This application has no specific restrictions on the type of electrolyte, and it can be selected according to needs.

[0143] In some embodiments, the electrolyte is an electrolyte solution comprising an electrolyte salt and a solvent.

[0144] In some embodiments, the electrolyte salt may be selected from one or more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalatoborate, lithium dioxalatoborate, lithium difluorodioxalatophosphate, and lithium tetrafluorooxalatophosphate.

[0145] In some embodiments, the solvent may be selected from one or more of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methylpropyl carbonate, ethylpropyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, cyclopentane, dimethyl sulfone, methyl ethyl sulfone and diethyl sulfone.

[0146] In some embodiments, the electrolyte may further include additives. For example, the additives may include negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain battery properties, such as additives that improve battery overcharge performance, and additives that improve battery high or low temperature performance.

[0147] [Isolation film]

[0148] In some embodiments, the battery further includes a separator. The present application has no particular limitation on the type of separator, and any known porous separator with good chemical and mechanical stability can be selected.

[0149] In some embodiments, the material of the separator can be selected from one or more of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator can be a single-layer film or a multi-layer composite film, without particular limitation. When the separator is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation.

[0150] In some embodiments, the positive electrode sheet, the negative electrode sheet, and the separator can be formed into an electrode assembly through a winding process or a lamination process.

[0151] The present application has no particular limitation on the shape of the battery, which can be cylindrical, square, or any other shape. For example, FIG7 shows a square-structured battery 5 as an example.

[0152] In some embodiments, referring to FIG8 , the outer packaging may include a housing 100 and a cover plate 110 . The positive electrode sheet, the negative electrode sheet, and the separator may be wound or laminated to form an electrode assembly 200 . The electrode assembly 200 is encapsulated within the housing cavity. The electrolyte is infiltrated into the electrode assembly 200 . The battery 5 may include one or more electrode assemblies 200, and those skilled in the art may select the number based on specific practical needs.

[0153] In some embodiments, batteries may be assembled into a battery module. The number of batteries contained in the battery module may be one or more. The specific number may be selected by those skilled in the art based on the application and capacity of the battery module.

[0154] Figure 9 shows an example battery module 4. Referring to Figure 9 , within the battery module 4, multiple batteries 5 may be arranged sequentially along the length of the battery module 4. Of course, they may also be arranged in any other manner. Furthermore, the multiple batteries 5 may be secured together using fasteners.

[0155] Optionally, the battery module 4 may further include a housing having a receiving space, and the plurality of batteries 5 are received in the receiving space.

[0156] In some embodiments, the battery modules described above may also be assembled into a battery pack. The battery pack may contain one or more battery modules, and the specific number may be selected by those skilled in the art based on the application and capacity of the battery pack.

[0157] Figures 10 and 11 illustrate an exemplary battery pack 1. Referring to Figures 10 and 11 , the battery pack 1 may include a battery box and multiple battery modules 4 disposed within the battery box. The battery box comprises an upper case 2 and a lower case 3. The upper case 2 can be positioned over the lower case 3 to form an enclosed space for accommodating the battery modules 4. The multiple battery modules 4 can be arranged in any manner within the battery box.

[0158] A fourth aspect of the present application provides an electrical device, comprising the battery provided in the third aspect of the present application. The electrical device may include, but is not limited to, mobile devices (e.g., mobile phones, laptops, etc.), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships, satellites, energy storage systems, and the like.

[0159] Figure 12 shows an example of an electric device. This device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the high power and high energy density requirements of the battery, a battery pack or battery module can be used.

[0160] Another example device may be a mobile phone, a tablet computer, a laptop computer, etc. Such a device is usually required to be light and thin, and may use a battery as a power source.

[0161] In order to make the technical problems, technical solutions and beneficial effects solved by the embodiments of the present application clearer, the following will be further described in detail with reference to the embodiments and drawings. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is in no way intended to limit the present application and its applications. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0162] Example 1

[0163] 1. Preparation of positive electrode sheet

[0164] The positive electrode active material LiFePO4, the conductive agent carbon black (Super P), and the binder polyvinylidene fluoride (PVDF) are fully stirred and mixed in an appropriate amount of solvent N-methylpyrrolidone (NMP) in a mass ratio of 80:15:5 to form a uniform positive electrode slurry; the positive electrode slurry is evenly coated on the surface of the positive electrode current collector aluminum foil, and after drying and cold pressing, the positive electrode sheet is obtained.

[0165] 2. Preparation of negative electrode sheet

[0166] Kuraray Type 1 hard carbon was used as the negative electrode active material. The hard carbon negative electrode active material, conductive agent carbon black (Super P), and binder carboxymethyl cellulose (CMC) were fully stirred and mixed in an appropriate amount of solvent deionized water at a mass ratio of 90:5:5 to form a uniform negative electrode slurry. The negative electrode slurry was evenly coated on the surface of the negative electrode current collector aluminum foil, and after drying and cold pressing, the negative electrode sheet was obtained.

[0167] 3. Prepare electrolyte

[0168] Equal volumes of ethylene carbonate (EC) and diethyl carbonate (DEC) were mixed to obtain an organic solvent, and then NaPF6 was dissolved in the organic solvent to prepare an electrolyte with a concentration of 1 mol / L.

[0169] 4. Isolation film

[0170] A porous polyethylene film was used as the separator.

[0171] 5. Preparation of electrode assembly

[0172] The positive electrode sheet, the separator, and the negative electrode sheet are wound in sequence so that the separator is placed between the positive electrode sheet and the negative electrode sheet to play an isolating role, thereby obtaining an electrode assembly.

[0173] 6. Prepare the shell

[0174] The thermal conductive filler, prepolymer, curing agent and dispersant are fully stirred and mixed in an appropriate amount of solvent in a mass ratio of 2:89:2:7 to form a uniform slurry. The slurry is applied to the bottom and side walls of the shell, where the side wall coating height H is 5 mm. After heating and curing, a shell with a thermal conductive insulation layer attached to the inner wall is obtained.

[0175] 7. Assemble the electrode assembly and the shell.

[0176] The preparation methods of the batteries and shells in Examples 2 to 25 and Comparative Examples 1 to 4 are the same as those in Example 1. The differences are detailed in Table 1.

[0177] Performance Testing

[0178] 1. Thermal conductivity test method

[0179] Test standard GB / T10295-2008

[0180] 2. Resistance test method

[0181] Use a withstand voltage tester with the negative terminal connected to the housing without a thermally conductive insulation layer and the positive terminal connected to the thermally conductive insulation layer. Perform the test in accordance with GB / T 1408.2-2016 and read the resistance value.

[0182] 3. Leakage current test method

[0183] Use a withstand voltage tester with the negative electrode connected to the side of the housing not provided with a thermally conductive insulation layer. The positive electrode of the withstand voltage tester is connected to the thermally conductive insulation layer on the housing. Test according to GB / T 1408.2-2016 and read the resistance value.

[0184] 4. Test method for corrosion of exterior structures

[0185] The electrode assembly was assembled into the shell, and the battery was charged to 33% state of charge (SOC). The negative electrode and the shell were connected with a wire and allowed to stand for 10 days. The shell was disassembled and the corrosion condition was observed.

[0186] 5. Electrolyte resistance test

[0187] Place the shell with a thermally conductive insulating layer in the electrolyte. After immersing the shell at 60°C for 1500 hours, overlap the negative electrode of the voltage tester with the side of the shell without the thermally conductive insulating layer, and overlap the positive electrode with the thermally conductive insulating layer on the shell. Give a DC voltage of 2700V and a test time of 60s to determine whether the film layer is broken down. Repeat 25 times.

[0188] 6. 4C fast charging heat dissipation experiment

[0189] The shell with a thermal insulating layer was assembled with the electrode assembly, and the battery was charged and discharged for 10 cycles at a 4C rate, and the temperature of the battery surface was recorded.

[0190] 7. Voltage test after soaking in electrolyte

[0191] Take out the sample soaked in electrolyte, dip it in ethanol to clean the residual electrolyte on the surface, turn on the voltage tester, overlap the negative electrode with the side of the shell without the thermal insulation layer, and overlap the positive electrode with the thermal insulation layer on the shell. Set the voltage DC to 2700V and the test time to 60s to determine whether the film layer is broken down.

[0192] The test results of Examples 1 to 25 and Comparative Examples 1 to 4 are shown in Table 2.

[0193] Table 2

[0194] Conclusion: It can be seen from Examples 1 to 25 and Comparative Examples 1 to 4 that the battery assembled into the shell proposed in this application can simultaneously reduce the temperature of the large surface of the battery cell, improve the pressure resistance of the thermally conductive insulating layer, and reduce the probability of corrosion caused by contact between the positive electrode collector or the negative electrode collector and the bottom wall of the shell.

[0195] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application, and they should all be included in the scope of the claims and specification of the present application. In particular, as long as there is no structural conflict, the various technical features mentioned in the various embodiments can be combined in any way. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

Claims

1. A housing, wherein: include: A heat-conducting insulating layer is provided on at least a portion of the inner surface of the shell, the thermal conductivity of the heat-conducting insulating layer is 0.03W / mK-10W / mK, and the resistance of the heat-conducting insulating layer under a high voltage of 1000V is 100MΩ-100GΩ.

2. The housing according to claim 1, wherein: The thermal conductivity of the thermally conductive insulating layer is 0.2W / mK-10W / mK, and the resistance of the thermally conductive insulating layer under a high voltage of 1000V is 500MΩ-50GΩ.

3. The housing according to claim 1 or 2, wherein: The leakage current of the thermally conductive insulating layer is 0-10 mA.

4. The housing according to any one of claims 1 to 3, wherein: The leakage current of the thermally conductive insulating layer is 0.01 mA-1 mA.

5. The housing according to any one of claims 1 to 4, wherein: The thermally conductive insulating layer comprises 1 to 50 parts by weight of a thermally conductive filler and 50 to 95 parts by weight of a prepolymer.

6. The housing according to any one of claims 1 to 5, wherein: The thermally conductive insulating layer comprises 10 to 30 parts by weight of a thermally conductive filler and 70 to 90 parts by weight of a prepolymer.

7. The housing according to claim 5 or 6, wherein: The thermally conductive filler includes one or more of inorganic particles having a dielectric constant of 5 or more and inorganic particles having ion conductivity but not storing ions.

8. The housing according to claim 7, wherein: One or more of the following conditions are met: The inorganic particles having a dielectric constant of 5 or more include boehmite, aluminum oxide, zinc oxide, silicon oxide, titanium oxide, zirconium oxide, barium oxide, calcium oxide, magnesium oxide, nickel oxide, tin oxide, cerium oxide, yttrium oxide, hafnium oxide, aluminum hydroxide, magnesium hydroxide, silicon carbide, boron carbide, aluminum nitride, silicon nitride, boron nitride, magnesium fluoride, calcium fluoride, barium fluoride, barium sulfate, magnesium aluminum silicate, lithium magnesium silicate, sodium magnesium silicate, bentonite, hectorite, zirconium titanate, barium titanate, Pb(Zr,Ti)O3, Pb 1-m La m Zr 1-n Ti n O3、Pb(Mg 1 / 3 Nb 2 / 3 ) one or more of O3PbTiO3 and their respective modified inorganic particles, 0<m<1, 0<n<1; The inorganic particles having ion conductivity but not storing ions include Li3PO4, lithium titanium phosphate Li x1 Ti y1 (PO4)3, Lithium Aluminum Titanate Phosphate Li x2 Al y2 Ti z1 (PO4)3, (LiAlTiP) x3 O y3 Type glass, lanthanum titanate lithium Li x4 La y4 TiO3, Lithium Germanium Phosphate Thiophosphate x5 Ge y5 P z2 S w 、Lithium Nitride Li x6 N y6 、SiS2 glass Li x7 Si y7 S z3 and P2S5 glass Li x8 P y8 S z4 One or more of, 0<x1<2, 0<y1<3, 0<x2<2, 0<y2<1, 0<z1<3, 0<x3<4, 0<y3<13, 0<x4<2, 0<y4<3, 0<x5<4, 0<y5<1, 0<z2<1, 0<w<5, 0<x6<4, 0<y6<2, 0<x7<3, 0<y7<2, 0<z3<4, 0<x8<3, 0<y8<3, 0<z4<7.

9. The housing according to any one of claims 5 to 8, wherein: The prepolymer includes one or more of polyimide, phenolic resin, urea-formaldehyde resin or epoxy resin.

10. The housing according to any one of claims 5 to 9, wherein: The thermally conductive insulating layer further includes at least one of a dispersant and a curing agent.

11. The housing according to claim 10, wherein: One or more of the following conditions are met: The dispersant includes sodium carboxymethyl cellulose, styrene-butadiene rubber, polyvinyl pyrrolidone, sodium lauryl sulfate, methyl amyl alcohol, polypropylene One or more of enamide or guar gum; The curing agent includes one or more of hexamethylenetetramine, ethylenediamine, hexamethylenediamine, diethylenetriamine, triethylenetetramine, p-phenylenediamine, m-phenylenediamine, terephthalic acid, terephthalic acid, maleic anhydride or phthalic anhydride.

12. The housing according to any one of claims 1 to 11, wherein: The thickness of the thermally conductive insulating layer is 1 μm-1000 μm.

13. The housing according to any one of claims 1 to 12, wherein: The thickness of the thermally conductive insulating layer is 20 μm-200 μm.

14. The housing according to any one of claims 1 to 13, wherein: The shell includes a bottom wall and a side wall, the side wall is connected to the edge of the bottom wall, the bottom wall and the side wall form a receiving cavity with an opening, and the thermal conductive insulation layer is arranged on at least part of the inner surface of the side wall and the bottom wall.

15. The housing according to claim 14, wherein: The thermally conductive insulating layer is disposed on the entire inner surface of the side wall and the entire inner surface of the bottom wall.

16. A method for preparing a shell, wherein: include: A heat-conducting insulating layer is formed on at least a portion of the inner surface of the shell, the thermal conductivity of the heat-conducting insulating layer is 0.03W / mK-10W / mK, and the resistance of the heat-conducting insulating layer under a high voltage of 1000V is 100MΩ-100GΩ.

17. The method according to claim 16, wherein: The method comprises: mixing 1 to 50 parts by weight of a thermally conductive filler, 50 to 95 parts by weight of a prepolymer and a solvent into a slurry, and forming the slurry on at least a portion of the inner surface of the housing to form the thermally conductive insulating layer.

18. The method according to claim 17, wherein: Also includes: At least one of a dispersant and a curing agent is added to the slurry to form the thermally conductive insulating layer.

19. The method according to any one of claims 16 to 18, wherein: The method further comprises: cleaning and activating the housing before forming the thermally conductive insulating layer.

20. A battery, wherein: A shell comprising any one of claims 1-15 or a shell prepared by the method of any one of claims 16-19.

21. The battery according to claim 20, wherein The shell comprises a bottom wall and a side wall, the side wall is connected to the edge of the bottom wall, the bottom wall and the side wall form a receiving cavity with an opening, the battery further comprises a positive electrode sheet, a negative electrode sheet and a separator, the positive electrode sheet, the negative electrode sheet and the separator are located in the receiving cavity, the positive electrode sheet comprises a positive electrode collector, the negative electrode sheet comprises a negative electrode collector, the positive projection of the separator on the side wall is located within the range of the positive projection of the negative electrode collector on the side wall and does not overlap, or the positive projection of the separator on the side wall is located within the range of the positive projection of the positive electrode collector on the side wall and does not overlap; The inner surface of the bottom wall is provided with the thermally conductive insulating layer, and the thermally conductive insulating layer is in contact with the negative electrode current collector or the positive electrode current collector.

22. The battery according to claim 21, wherein The orthographic projection of the separator on the side wall is located within the range of the orthographic projection of the negative electrode current collector on the side wall and does not overlap.

23. The battery according to claim 22, wherein The negative electrode current collector includes a first region and a second region, wherein the orthographic projection of the first region on the side wall coincides with the orthographic projection of the separator on the side wall, and the orthographic projection of the second region on the side wall is within the orthographic projection range of the thermally conductive insulating layer on the side wall.

24. The battery according to claim 23, wherein Along the extension direction of the negative electrode current collector, the length of the second region is D, and satisfies 1 mm≤D≤5 mm.

25. The battery according to any one of claims 22 to 24, wherein: An end of the orthographic projection of the heat-conducting insulating layer on the side wall close to the opening of the accommodating cavity coincides with an end of the orthographic projection of the diaphragm on the side wall away from the opening of the accommodating cavity.

26. The battery according to claim 25, wherein Along the extension direction of the negative electrode current collector, the height of the thermally conductive insulating layer on the side wall is H, and H is ≥ 5 mm.

27. The battery according to claim 25 or 26, wherein Along the extension direction of the negative electrode current collector, the height of the thermally conductive insulating layer on the side wall is H, and 1 cm≤H≤3 cm.

28. The battery according to any one of claims 22 to 27, wherein: The battery comprises: a top cover assembly, which is suitable for closing the opening of the accommodating cavity; the side walls are provided with the thermally conductive insulating layer, and an end of the thermally conductive insulating layer close to the top cover assembly is spaced apart from an end of the top cover assembly close to the shell.

29. The battery according to claim 28, wherein The distance between one end of the heat-conducting insulation layer close to the top cover assembly and one end of the top cover assembly close to the shell is L, and 2mm≤L≤5mm.

30. An electrical device, wherein: A battery comprising any one of claims 20-29.

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