Battery pack

Abstract

The battery pack comprises a box body, a battery assembly, a pressure release valve and a flame-retardant layer, the box body is provided with a mounting cavity, the battery assembly is located in the mounting cavity, the pressure release valve selectively communicates with the mounting cavity, the flame-retardant layer expands and becomes larger when the temperature exceeds a preset temperature, and the flame-retardant layer is arranged on at least one of the box body, the battery assembly and the pressure release valve. The flame-retardant layer comprises at least one of a first material layer, a second material layer and a third material layer, the first material layer comprises expanded graphite and an inorganic filler, the second material layer comprises ammonium polyphosphate, melamine and an alcohol compound, and the third material layer comprises expanded graphite and a synergist; the flame-retardant layer is arranged on at least one of the box body, the battery assembly and the pressure release valve, and the volume of the flame-retardant layer is expanded and increased under the condition that the temperature exceeds the preset temperature, so that outward thermal diffusion of the battery pack after thermal runaway is inhibited, and the battery pack is difficult to fire and explode after thermal runaway.

Description

Technical Field

[0001] This application relates to the field of battery technology, and more particularly to a battery pack. Background Technology

[0002] Battery packs are at risk of thermal runaway under conditions such as short circuits, overcharging, over-discharging, exceeding temperature limits, and mechanical damage. With the increasing popularity of electric vehicles and the growing number of electric vehicles on the road, battery pack thermal runaway accidents are becoming more frequent. When a battery pack experiences thermal runaway, heat will diffuse outwards, potentially leading to fire or explosion. Summary of the Invention

[0003] This application provides a battery pack that is less likely to catch fire or explode after thermal runaway, thereby at least partially solving the above-mentioned technical problems.

[0004] To achieve the above objectives, this application provides a battery pack comprising:

[0005] The enclosure has a mounting cavity;

[0006] A battery assembly located within a mounting cavity;

[0007] A pressure relief valve, which may be connected to the mounting cavity;

[0008] A flame-retardant layer that expands when a preset temperature is exceeded, and the flame-retardant layer is disposed in at least one of the housing, battery assembly and pressure relief valve;

[0009] The flame-retardant layer includes at least one of a first material layer, a second material layer, and a third material layer. The first material layer includes expanded graphite and inorganic fillers. The second material layer includes ammonium polyphosphate, melamine, and alcohol compounds. The third material layer includes expanded graphite and a synergist.

[0010] Optionally, the enclosure includes a base and a cover, the base and cover forming a mounting cavity, and the flame-retardant layer is disposed on at least one surface of the cover; and / or,

[0011] The flame-retardant layer is disposed inside the box lid; and / or,

[0012] The flame-retardant layer comprises at least two material layers and an adhesive layer connecting adjacent material layers, and the flame-retardant layer is disposed on at least one surface of the lid.

[0013] Optionally, the enclosure includes a central channel disposed within the mounting cavity and a fireproof cover disposed within the central channel, the flame-retardant layer being disposed on at least one surface of the fireproof cover; and / or,

[0014] The flame-retardant layer is disposed inside the fireproof cover.

[0015] Optionally, the enclosure includes a fireproof blanket covering the battery assembly, and the flame-retardant layer is disposed on at least one surface of the fireproof blanket; and / or,

[0016] The flame-retardant layer is disposed within the fireproof blanket; and / or,

[0017] The flame-retardant layer comprises at least two material layers and an adhesive layer, and the flame-retardant layer is disposed on at least one surface of the fire blanket.

[0018] Optionally, the battery assembly includes a plurality of battery modules, each battery module having electrode plates, and the flame-retardant layer is disposed on at least one surface of the electrode plates; and / or,

[0019] The flame-retardant layer is disposed within the electrode sheet; and / or,

[0020] The flame-retardant layer comprises at least two material layers and an adhesive layer, and the flame-retardant layer is disposed on at least one surface of the electrode sheet.

[0021] Optionally, the battery assembly includes multiple battery modules, a switch electrically connected to the battery modules, and a protective cover disposed on the switch, wherein the flame-retardant layer is disposed on at least one surface of the protective cover; and / or,

[0022] The flame-retardant layer is disposed inside the protective cover; and / or,

[0023] The flame-retardant layer comprises at least two material layers and an adhesive layer, and the flame-retardant layer is disposed on at least one surface of the protective cover.

[0024] Optionally, the pressure relief valve includes a valve seat disposed on the tank cover and a valve plate cooperating with the valve seat, wherein the flame-retardant layer is disposed on at least one surface of the valve plate; and / or,

[0025] The flame-retardant layer is disposed within the valve plate; and / or,

[0026] The flame-retardant layer comprises at least two material layers and an adhesive layer, and the flame-retardant layer is disposed on at least one surface of the valve seat and / or valve plate.

[0027] Optionally, the thickness of the first material layer is between 1 mm and 2 mm, the thickness of the second material layer is between 1 mm and 3 mm, and the thickness of the third material layer is between 10 μm and 200 μm.

[0028] The density of the first material layer is between 1.2 g / cm³. 3 Up to 1.8 g / cm 3 The density of the second material layer is between 1.0 g / cm³. 3 Up to 1.5g / cm 3The density of the third material layer is between 1.1 g / cm³. 3 Up to 1.6 g / cm 3 between;

[0029] The expansion ratio of the first material layer is between 10 and 200 times, the expansion ratio of the second material layer is between 10 and 30 times, and the expansion ratio of the third material layer is between 5 and 15 times.

[0030] Optionally, the mass percentage of expanded graphite in the first material layer is 10% to 30%.

[0031] In the second material layer, the mass percentage of ammonium polyphosphate is 20% to 30%, and the mass percentage of melamine is 15% to 20%.

[0032] In the third material layer, the synergist is selected from at least one of montmorillonite, zeolite, and boron-containing compounds.

[0033] Optionally, the battery assembly includes a battery module, the battery module including at least one battery cell, the battery cell comprising:

[0034] A housing includes a housing base and a housing cover, the housing base and the housing cover together forming a receiving cavity, the housing cover having a first surface facing away from the receiving cavity and a second surface facing the receiving cavity;

[0035] An electrode assembly located within a receiving cavity;

[0036] An explosion-proof valve, which may be selectively connected to a receiving cavity;

[0037] Wherein, the flame-retardant layer is disposed on the first surface; and / or,

[0038] The flame-retardant layer is disposed between the first surface and the second surface; and / or,

[0039] The flame-retardant layer is disposed on the explosion-proof valve.

[0040] In the battery pack of this application embodiment, a flame-retardant layer is provided on at least one of the housing, battery components and pressure relief valve. The flame-retardant layer expands in volume when the temperature exceeds a preset value, thereby suppressing the outward thermal diffusion after the battery pack experiences thermal runaway, making it less likely for the battery pack to catch fire or explode after thermal runaway.

[0041] Other features and advantages of this application will be described in detail in the following detailed description section. Attached Figure Description

[0042] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0043] To gain a more complete understanding of this application and its beneficial effects, the following description will be provided in conjunction with the accompanying drawings, wherein the same reference numerals in the following description denote the same parts.

[0044] Figure 1 This is an exploded view of a single battery cell provided in an exemplary embodiment of this disclosure;

[0045] Figure 2 This is a cross-sectional view of the shell cover provided in an exemplary embodiment of this disclosure;

[0046] Figure 3 This is a cross-sectional view of the shell cover provided in another exemplary embodiment of this disclosure;

[0047] Figure 4 This is a cross-sectional view of the shell cover provided in yet another exemplary embodiment of this disclosure;

[0048] Figure 5 This is an exploded view of the battery pack provided in an exemplary embodiment of this disclosure.

[0049] Explanation of reference numerals in the attached figures:

[0050] 1. Enclosure; 11. Enclosure base; 12. Enclosure cover; 13. Mounting cavity; 14. Central channel;

[0051] 2. Battery module; 21. Battery cell; 211. Housing; 2111. Housing base; 2112. Housing cover; 21121. First cover; 21122. Second cover; 21123. First surface; 21124. Second surface; 2113. Receiving cavity; 2114. Electrode terminal; 212. Electrode assembly; 213. Explosion-proof valve;

[0052] 3. Pressure relief valve;

[0053] 4. Flame-retardant layer; 4a. First flame-retardant layer; 4a1. First clearance hole; 4a2. Second clearance hole; 4b. Second flame-retardant layer; 4c. Fifth flame-retardant layer; 41. First material layer; 42. Second material layer; 43. Third material layer; 44. Adhesive layer. Detailed Implementation

[0054] 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 a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the protection scope of this application.

[0055] It should be understood that terms such as “having,” “comprising,” and “including” as used herein do not exclude the presence or addition of one or more other elements or combinations thereof.

[0056] In the various figures of this application, for ease of illustration, certain dimensions of structures or parts may be exaggerated relative to other structures or parts; therefore, they are only used to illustrate the basic structure of the subject matter of this application.

[0057] According to the first aspect of this application, referring to Figures 1 to 4 This disclosure provides a battery cell 21, including a housing 211, an electrode assembly 212, an explosion-proof valve 213, and a flame-retardant layer 4.

[0058] In this embodiment, the battery cell 21 can be a lithium-ion battery cell, a sodium-ion battery cell, a lithium metal battery cell, a sodium metal battery cell, etc., and this application embodiment is not limited in this regard. There is no particular limitation on the shape of the battery cell; it can be a cylinder, a cuboid, or any other arbitrary shape.

[0059] In some embodiments, the housing 211 includes a housing base 2111 and a housing cover 2112, which together form a receiving cavity 2113.

[0060] In this embodiment, the housing 2111 is an open structure with an opening on one side, and the cover 2112 covers the opening of the housing 2111 to form a sealed connection, thereby forming a closed receiving cavity 2113. When the housing 2111 and the cover 2112 are connected to each other, the mating point between the housing 2111 and the cover 2112 can also be sealed, thereby improving the sealing performance of the receiving cavity 2113.

[0061] In some embodiments, the cover 2112 has a first surface 21123 facing away from the receiving cavity 2113 and a second surface 21124 facing the receiving cavity 2113.

[0062] In this embodiment, the first surface 21123 is exposed to the outside of the receiving cavity 2113, and the first surface 21123 can be understood as the outer surface of the housing 211. The second surface 21124 is exposed to the inside of the receiving cavity 2113, and the second surface 21124 can be understood as the inner surface of the housing 211.

[0063] In some embodiments, the electrode assembly 212 is located within the receiving cavity 2113.

[0064] In this embodiment, the electrode assembly 212 includes a positive electrode, a negative electrode, and a separator. The battery cell 21 mainly relies on the movement of active ions between the positive and negative electrode to function.

[0065] In this embodiment, the battery cell 21 also includes an electrolyte. The receiving cavity 2113 of the housing 211 can be used to accommodate the electrode assembly 212, and can also be used to accommodate the electrolyte, such as a liquid electrolyte (also known as an electrolyte solution), thereby providing a sealed space for the electrode assembly 212 and the electrolyte.

[0066] In some embodiments, the explosion-proof valve 213 may be selectively connected to the receiving cavity 2113.

[0067] In this embodiment, the explosion-proof valve 213 can be used to discharge the internal gas of the battery cell 21 (i.e., the receiving cavity 2113).

[0068] As an example, the internal pressure or temperature of the battery cell 21 is actuated to release the internal pressure or temperature when it reaches a predetermined threshold. When the internal pressure or temperature of the battery cell 21 reaches the predetermined threshold, the explosion-proof valve 213 actuates or a weak structure in the explosion-proof valve 213 is damaged, thereby forming an opening or channel for the release of internal pressure or temperature. This threshold design varies depending on the design requirements. The threshold may depend on the materials of one or more of the positive electrode, negative electrode, electrolyte, and separator in the battery cell 21.

[0069] In this embodiment, a gap may be provided between the electrode assembly 212 and the housing 211. This gap can serve as a pressure relief channel. When the battery cell 21 experiences thermal runaway, the emissions that are far from the explosion-proof valve 213 can flow from the pressure relief channel to the explosion-proof valve 213.

[0070] In some embodiments, the flame-retardant layer 4 expands and enlarges when the temperature exceeds a preset limit.

[0071] In this embodiment, after the flame retardant layer 4 reaches or exceeds a preset temperature (for example, when a single cell experiences thermal runaway), its volume expands and increases. During the expansion process, a phase change occurs, which allows it to absorb heat and thus absorb the heat released during thermal runaway.

[0072] In this embodiment, after the flame-retardant layer 4 expands, it can block air, thereby retarding the thermal runaway area. The expanded flame-retardant layer 4 can also effectively seal or block the spread of ejected materials, improving safety characteristics. Furthermore, the expanded flame-retardant layer 4 can suppress the diffusion of smoke and reduce the temperature of the ejected airflow or flame, thereby reducing the pressure on the thermal protection of the battery cell 21.

[0073] In this embodiment, the flame-retardant layer 4 is made of flame-retardant material, which can effectively retard flames and reduce the total heat generated after thermal runaway.

[0074] In this embodiment, when the flame-retardant layer 4 is normally expanding due to gas generation inside the battery cell 21, it will not be triggered to expand because the preset temperature has not been reached, thus not affecting the normal operation of the battery cell 21.

[0075] In this embodiment, the preset temperature can be between 100℃ and 200℃. For example, the preset temperature can be 100℃, 110℃, 120℃, 130℃, 140℃, 150℃, 160℃, 170℃, 180℃, 190℃, or 200℃. Of course, the preset temperature can also be any value between 100℃ and 200℃.

[0076] In this embodiment, the closer the flame-retardant layer 4 is to the receiving cavity 2113, the lower the preset temperature can be set.

[0077] In some embodiments, the flame retardant layer 4 is disposed at least between the first surface 21123 and the second surface 21124.

[0078] In this embodiment, the flame-retardant layer 4 is disposed on the first surface 21123, and / or the flame-retardant layer 4 is disposed between the first surface 21123 and the second surface 21124, and / or the flame-retardant layer 4 is disposed on the explosion-proof valve 213.

[0079] In this embodiment, considering that the casing 2112 and explosion-proof valve 213 of the battery cell 21 are easily affected by external forces, a flame-retardant layer 4 is provided. The flame-retardant layer 4 expands and enlarges when the temperature exceeds the preset temperature, thereby blocking or preventing the ejected material from being ejected outward along the casing 2112 and explosion-proof valve 213, and suppressing the diffusion of smoke.

[0080] By utilizing the flame-retardant layer 4 to expand in volume when the temperature exceeds a preset temperature, the thermal runaway of the battery cell 21 is suppressed, thereby preventing the thermal diffusion outward after thermal runaway. This makes it less likely for the battery cell 21 to catch fire or explode after thermal runaway.

[0081] In some embodiments, continue to refer to Figure 2 As shown, the battery cell 21 includes a first flame-retardant layer 4a, which has a first clearance hole 4a1 and a second clearance hole 4a2.

[0082] In this embodiment, when the first flame-retardant layer 4a is disposed on the first surface 21123 of the cover 2112, it is avoided by setting the first clearance hole 4a1 and the second clearance hole 4a2 to avoid affecting the normal operation of other components on the first surface 21123.

[0083] In some embodiments, housing 211 includes electrode terminals 2114.

[0084] In this embodiment, there can be two electrode terminals 2114. The two electrode terminals 2114 are defined as a positive electrode terminal and a negative electrode terminal, respectively. Both the positive electrode terminal and the negative electrode terminal are used to be electrically connected to the electrode assembly 212 to output the electrical energy generated by the electrode assembly 212.

[0085] In some embodiments, the electrode terminal 2114 protrudes from the first surface 21123 and passes through the first clearance hole 4a1, and the explosion-proof valve 213 is disposed on the first surface 21123 and is opposite to the second clearance hole 4a2.

[0086] In this embodiment, the first flame-retardant layer 4a makes way for the electrode terminal 2114 and the explosion-proof valve 213 that protrude from the first surface 21123, so as to avoid affecting the normal operation of the electrode terminal 2114 and the explosion-proof valve 213.

[0087] In this embodiment, by applying the flame-retardant layer 4 (i.e., the first flame-retardant layer 4a) as a coating to the first surface 21123 of the cover 2112, arcing and the spread of smoke can be suppressed, and the temperature of the ejected airflow or flame can be reduced, thereby reducing the pressure on the thermal protection of the battery cell 21.

[0088] In this embodiment, except for the electrode terminals 2114 and the explosion-proof valve 213, the remaining areas of the first surface 21123 are covered with a flame-retardant layer 4 (i.e., the first flame-retardant layer 4a), which effectively increases the protective area and improves the protective effect. Compared with the solution of "setting the flame-retardant layer 4 on the explosion-proof valve 213", setting the flame-retardant layer 4 (e.g., the first flame-retardant layer 4a) on the cover 2112 (e.g., the first surface 21123 of the cover 2112) can increase the surface area of ​​the flame-retardant layer 4 and reduce the manufacturing difficulty of the flame-retardant layer 4.

[0089] In some embodiments, continue to refer to Figure 3 As shown, the battery cell 21 includes a second flame-retardant layer 4b, and the cover 2112 has a first cover 21121 forming a first surface 21123 and a second cover 21122 forming a second surface 21124, with the second flame-retardant layer 4b located between the first cover 21121 and the second cover 21122.

[0090] In this embodiment, the flame-retardant layer 4 (i.e., the second flame-retardant layer 4b) is disposed in the shell cover 2112 in the form of a sandwich, that is, located between the first cover 21121 and the second cover 21122. When the flame-retardant layer 4 expands, it can force the first cover 21121 and the second cover 21122 on both sides to deform or break, thereby suppressing arcing and the diffusion of smoke.

[0091] In this embodiment, compared to the flame-retardant layer 4 in the form of a coating (e.g., the first flame-retardant layer 4a), the flame-retardant layer 4 in the form of a sandwich (e.g., the second flame-retardant layer 4b) obtains heat through the first cover 21121 and the second cover 21122 on both sides, so that the flame-retardant layer 4 needs to be at a higher external temperature to reach the preset temperature and expand.

[0092] In this embodiment, since the rigidity of the flame-retardant layer 4 is weaker than that of the shell cover 2112, and it even has a certain degree of flexibility, and the flame-retardant layer 4 (e.g., the second flame-retardant layer 4b) is located between the first cover 21121 and the second cover 21122, the sandwich-type flame-retardant layer 4 (e.g., the second flame-retardant layer 4b) has better blast resistance and energy absorption buffering capabilities. Moreover, the sandwich-type flame-retardant layer 4 (e.g., the second flame-retardant layer 4b) can also reduce the weight of the shell cover 2112.

[0093] For example, the sandwich-type flame-retardant layer 4 can be configured as a single layer, such as... Figure 3 The cover 2112 is formed by sequentially connecting the first cover body 21121, the second flame-retardant layer 4b, and the second cover body 21122, forming a structure similar to a sandwich. Of course, the flame-retardant layer 4 in the sandwich form can also be configured as multiple layers.

[0094] In some embodiments, the explosion-proof valve 213 includes an explosion-proof disc.

[0095] In this embodiment, the explosion-proof valve 213 also includes a valve body disposed on the housing cover 2112. A pressure relief channel is formed within the valve body. When the internal pressure or temperature of the battery cell 21 reaches a critical value, at least a portion of the explosion-proof sheet ruptures, breaks, tears, or opens to open the pressure relief channel, ensuring the safety of the battery cell 21. When the explosion-proof sheet is not ruptured, it seals the pressure relief channel, preventing the receiving cavity 2113 from communicating with the outside through the pressure relief channel.

[0096] In some embodiments, the explosion-proof sheet has a third surface facing away from the receiving cavity 2113 and a fourth surface facing the receiving cavity 2113.

[0097] In this embodiment, the third surface is exposed to the outside of the receiving cavity 2113, and the third surface can be understood as the outer surface of the explosion-proof sheet. The fourth surface is exposed to the inside of the receiving cavity 2113, and the fourth surface can be understood as the inner surface of the explosion-proof sheet.

[0098] In some embodiments, the battery cell 21 includes a third flame-retardant layer disposed on a third surface; and / or, the battery cell 21 includes a fourth flame-retardant layer disposed between the third surface and the fourth surface.

[0099] In this embodiment, by applying the flame-retardant layer 4 (e.g., the third flame-retardant layer) as a coating to the third surface of the explosion-proof sheet, arcing and smoke diffusion can be suppressed, and the temperature of the ejected airflow or flame can be reduced, thereby reducing the pressure on the thermal protection of the battery cell 21.

[0100] In this embodiment, the flame-retardant layer 4 (e.g., the fourth flame-retardant layer) is sandwiched within the explosion-proof sheet, specifically between the third and fourth surfaces. When the flame-retardant layer 4 expands, it forces the explosion-proof sheet to deform or rupture on the third and fourth surfaces, thereby suppressing arcing and the spread of smoke.

[0101] In this embodiment, by providing a flame-retardant layer 4 (e.g., a third flame-retardant layer and / or a fourth flame-retardant layer) at the explosion-proof sheet, the diffusion of smoke can be suppressed, and the temperature of the ejected airflow (e.g., when there is a small amount of ejected airflow at the explosion-proof sheet) or flame can be reduced, thereby reducing the thermal protection pressure of the battery cell 21.

[0102] In this embodiment, when the battery cell 21 experiences thermal runaway, the ejected airflow is mainly discharged through the explosion-proof valve 213. Compared with the solution of "setting the flame-retardant layer 4 on the shell cover 2112", setting the flame-retardant layer 4 on the explosion-proof valve 213 (e.g., an explosion-proof sheet) can more directly suppress thermal runaway.

[0103] In some embodiments, the flame retardant layer 4 includes at least one of a first material layer 41, a second material layer 42, and a third material layer 43.

[0104] In this embodiment, the flame retardant layer 4 includes a first material layer 41, and / or includes a second material layer 42, and / or includes a third material layer 43.

[0105] In this embodiment, the flame-retardant layer 4 (e.g., the first flame-retardant layer 4a, the second flame-retardant layer 4b, the third flame-retardant layer, and the fourth flame-retardant layer) can be composed of at least one material layer. That is, the first material layer 41, the second material layer 42, and the third material layer 43 can be arbitrarily combined, as long as the flame-retardant layer 4 has more than one material layer. Moreover, the order and number of different material layers can be arbitrarily set as needed.

[0106] In some embodiments, the first material layer 41 includes expanded graphite and inorganic fillers.

[0107] In this embodiment, the first material layer 41 can at least achieve the function of heat insulation after expanding at a preset temperature.

[0108] In some embodiments, the second material layer 42 includes ammonium polyphosphate, melamine, and alcohol compounds.

[0109] In this embodiment, after the second material layer 42 expands at a preset temperature, it can at least suppress the formation of flue gas.

[0110] In some embodiments, the third material layer 43 includes expanded graphite and a synergist.

[0111] In this embodiment, by using different synergists, the third material layer 43 can perform more functions after expanding at a preset temperature. For example, it can simultaneously perform the functions of the first material layer 41 and the second material layer 42, thereby achieving the functions of heat insulation and inhibiting flue gas formation.

[0112] In some embodiments, continue to refer to Figure 4 As shown, the battery cell 21 includes a fifth flame-retardant layer 4c, which includes at least two material layers and an adhesive layer 44 connecting adjacent material layers.

[0113] In this embodiment, the flame-retardant layer 4 (e.g., the fifth flame-retardant layer 4c) is constructed by stacking or compositing multiple layers of materials, thereby achieving functional integration. For example, when the flame-retardant layer 4 (e.g., the fifth flame-retardant layer 4c) is constructed by stacking or compositing the first material layer 41 and the second material layer 42, it can simultaneously achieve the functions of heat insulation and smoke suppression, thus achieving functional integration.

[0114] In this embodiment, the composite flame-retardant layer 4 (e.g., the fifth flame-retardant layer 4c), compared to the single-layer flame-retardant layer 4, can simultaneously achieve both mechanical and flame-retardant properties, ensuring good strength while improving its flame-retardant safety. Furthermore, it can enhance the durability of the flame-retardant layer 4 when providing safety protection.

[0115] In some embodiments, a fifth flame-retardant layer 4c is disposed in at least one of the housing 2111, the housing cover 2112, and the explosion-proof valve 213.

[0116] In this embodiment, compared with a flame retardant layer 4 having a single material layer, when a composite flame retardant layer 4 (e.g., a fifth flame retardant layer 4c) is disposed at the housing 2111, housing cover 2112 and explosion-proof valve 213, the protective effect at each location can be improved, such as sealing or blocking the spread of ejected materials, suppressing smoke, heat insulation, and suppressing arcing.

[0117] For example, the composite flame retardant layer 4 (e.g., the fifth flame retardant layer 4c) may be disposed on or inside at least one surface of the housing 2111, the housing cover 2112 and the explosion-proof valve 213.

[0118] For example, a composite flame-retardant layer 4 (e.g., a fifth flame-retardant layer 4c) is disposed on the outer wall and / or inner wall of the housing 2111. A composite flame-retardant layer 4 (e.g., a fifth flame-retardant layer 4c) is disposed on the first surface 21123 and / or the second surface 21124 of the housing cover 2112. A composite flame-retardant layer 4 (e.g., a fifth flame-retardant layer 4c) is disposed on the valve body and / or explosion-proof plate of the explosion-proof valve 213.

[0119] In some embodiments, flame retardant layer 4 is coated on the first surface 21123.

[0120] In this embodiment, the flame-retardant layer 4 in the form of a coating (e.g., the first flame-retardant layer 4a) can be applied by coating, for example, applied to the first surface 21123 of the cover 2112.

[0121] In this embodiment, the coating or plating process is relatively simple, the thickness of the flame-retardant layer 4 is easy to control, and a relatively thin flame-retardant layer 4 can be prepared. Furthermore, the process is simple to operate and the manufacturing cost is low.

[0122] For example, taking the second material layer 42 as an example, when the flame retardant layer 4 is formed by coating process, firstly, modified ammonium polyphosphate (APP) is mixed with melamine (MEL) and alcohol compounds, and then dispersed in water-based epoxy resin. After that, a silane coupling agent is added, and then the flame retardant layer 4 placed on the first surface 21123 can be obtained by high-pressure spraying or other methods.

[0123] In some embodiments, the flame retardant layer 4 is hot-pressed into the shell cover 2112 and located between the first surface 21123 and the second surface 21124.

[0124] In this embodiment, the flame-retardant layer 4 in the form of a sandwich (e.g., the second flame-retardant layer 4b) can be set by hot pressing, for example, set inside the shell cover 2112.

[0125] For example, taking the flame-retardant layer 4 as an example where the third material layer 43 is used, the flame-retardant layer 4 is formed by hot pressing. First, a flame-retardant intermediate layer needs to be prepared. For example, expanded graphite is mixed with a synergist (such as montmorillonite), and after stirring and heating, a plastic intermediate material can be obtained. Then, the surface of the substrate (such as the first cover 21121 and the second cover 21122) is treated, such as by sandblasting and zinc phosphate conversion film treatment on the metal layer to increase mechanical interlocking and chemical bonding. Finally, hot pressing is performed. For example, the flame-retardant layer 4 is placed between two substrates (such as the first cover 21121 and the second cover 21122) and hot pressing is performed to realize the sandwich-type flame-retardant layer 4 (such as the second flame-retardant layer 4b).

[0126] In some embodiments, the flame retardant layer 4 is coated on the explosion-proof valve 213, and / or the flame retardant layer 4 is hot-pressed into the explosion-proof valve 213.

[0127] In this embodiment, the flame-retardant layer 4 in the form of a coating (e.g., the third flame-retardant layer) can be applied by coating, for example, by applying it to the third surface of the explosion-proof sheet. The flame-retardant layer 4 in the form of a sandwich layer (e.g., the fourth flame-retardant layer) can be applied by hot pressing, for example, by applying it inside the explosion-proof sheet.

[0128] In addition, the composite flame retardant layer 4 (e.g., the fifth flame retardant layer 4c) can be formed by a coating process.

[0129] For example, when a composite flame-retardant layer 4 (e.g., a fifth flame-retardant layer 4c) is provided on the first surface 21123 and / or the second surface 21124 of the housing 2112, the flame-retardant layer 4 includes a first material layer 41 and a second material layer 42. The first material layer 41 is the outermost layer, achieving a better heat insulation effect. The second material layer 42 is located on the side of the first material layer 41 facing the housing 2112, thereby effectively suppressing the formation of smoke. The first material layer 41 and the second material layer 42 are then bonded together by an adhesive layer (e.g., a metal layer), which increases the adhesion between the metal cross-section and the polymer interface.

[0130] It is understood that the flame retardant layer 4 in the form of a coating, the flame retardant layer 4 in the form of a sandwich, and the flame retardant layer 4 in the form of a composite can be applied to a metal material (such as the cover 2112) or to a non-metallic material (such as the fire blanket of the battery pack).

[0131] In some embodiments, the thickness of the first material layer 41 is between 1 mm and 2 mm.

[0132] In this embodiment, the thickness of the first material layer 41 can be 1 mm, 1.5 mm, or 2 mm. Of course, the thickness of the first material layer 41 can also be any value between 1 mm and 2 mm.

[0133] In some embodiments, the thickness of the second material layer 42 is between 1 mm and 3 mm.

[0134] In this embodiment, the thickness of the second material layer 42 can be 1 mm, 1.5 mm, 2 mm, 2.5 mm, or 3 mm. Of course, the thickness of the second material layer 42 can also be any value between 1 mm and 3 mm.

[0135] In some embodiments, the thickness of the third material layer 43 is between 10 μm and 200 μm.

[0136] In this embodiment, the thickness of the third material layer 43 can be 10μm, 50μm, 100μm, 150μm, or 200μm. Of course, the thickness of the third material layer 43 can also be any value between 10μm and 200μm.

[0137] In some embodiments, the density of the first material layer 41 is between 1.2 g / cm³. 3 Up to 1.8 g / cm 3 between.

[0138] In this embodiment, the density of the first material layer 41 can be 1.2 g / cm³. 3 1.3g / cm 3 1.4g / cm 3 1.5g / cm 3 1.6g / cm 3 1.7g / cm 3 1.8g / cm 3 Of course, the density of the first material layer 41 can also be between 1.2 g / cm³. 3 Up to 1.8 g / cm 3 Any value between.

[0139] In some embodiments, the density of the second material layer 42 is between 1.0 g / cm³. 3 Up to 1.5g / cm 3 between.

[0140] In this embodiment, the density of the second material layer 42 can be 1.0 g / cm³. 3 1.1g / cm 3 1.2g / cm 3 1.3g / cm 3 1.4g / cm 3 1.5g / cm 3 Of course, the density of the second material layer 42 can also be between 1.0 g / cm³. 3 Up to 1.5g / cm 3 Any value between.

[0141] In some embodiments, the density of the third material layer 43 is between 1.1 g / cm³. 3 Up to 1.6 g / cm 3 between.

[0142] In this embodiment, the density of the third material layer 43 can be 1.1 g / cm³. 3 1.2g / cm 3 1.3g / cm 3 1.4g / cm 3 1.5g / cm 31.6g / cm 3 Of course, the density of the third material layer 43 can also be between 1.1 g / cm³. 3 Up to 1.6 g / cm 3 Any value between.

[0143] In some embodiments, the expansion factor of the first material layer 41 is between 10 and 200.

[0144] In this embodiment, the expansion ratio of the first material layer 41 can be 10 times, 50 times, 100 times, 150 times, or 200 times. Of course, the expansion ratio of the first material layer 41 can also be any value between 10 times and 200 times.

[0145] In some embodiments, the expansion factor of the second material layer 42 is between 10 and 30 times.

[0146] In this embodiment, the expansion ratio of the second material layer 42 can be 10 times, 15 times, 20 times, 25 times, or 30 times. Of course, the expansion ratio of the second material layer 42 can also be any value between 10 times and 30 times.

[0147] In some embodiments, the expansion factor of the third material layer 43 is between 5 and 15 times.

[0148] In this embodiment, the expansion ratio of the third material layer 43 can be 5 times, 8 times, 10 times, 12 times, or 15 times. Of course, the expansion ratio of the third material layer 43 can also be any value between 5 times and 15 times.

[0149] In some embodiments, the mass percentage of expanded graphite in the first material layer 41 is 10% to 30%.

[0150] In this embodiment, the mass percentage of expanded graphite in the first material layer 41 can be 10%, 15%, 20%, 25%, or 30%. Of course, the mass percentage of expanded graphite in the first material layer 41 can also be any value between 10% and 30%.

[0151] In some embodiments, the mass percentage of ammonium polyphosphate in the second material layer 42 is 20% to 30%, and the mass percentage of melamine is 15% to 20%.

[0152] In this embodiment, the mass percentage of ammonium polyphosphate in the second material layer 42 can be 20%, 22%, 24%, 25%, 26%, 28%, or 30%. Of course, the mass percentage of ammonium polyphosphate in the second material layer 42 can also be any value between 20% and 30%.

[0153] In this embodiment, the mass percentage of melamine in the second material layer 42 can be 15%, 16%, 17%, 18%, 19%, or 20%. Of course, the mass percentage of melamine in the second material layer 42 can also be any value between 15% and 20%.

[0154] In some embodiments, the synergist in the third material layer 43 is selected from at least one of montmorillonite, zeolite, and boron-containing compounds.

[0155] In this embodiment, montmorillonite possesses good adsorption properties (e.g., adsorption of stationary gases) and safety (e.g., non-toxic and non-corrosive), effectively suppressing flue gas while improving the safety of the battery cell 21. Zeolite also possesses good adsorption properties (e.g., adsorption of stationary gases), effectively suppressing flue gas. Boron-containing compounds possess good flame retardancy (e.g., reducing material flammability), effectively providing flame retardancy.

[0156] For example, the first material layer 41 can be manufactured using a dry compounding and extrusion molding method. First, natural graphite is subjected to acid intercalation treatment to obtain expanded graphite; then, the expanded graphite is premixed with inorganic fillers, etc., and then melt-blended using a screw extruder, and finally extruded to obtain the first material layer 41.

[0157] For example, when manufacturing the second material layer 42, ammonium polyphosphate is used as the core acid source. It is necessary to first obtain high-polymerization degree ammonium polyphosphate, which can be obtained by high-temperature ammonia atmosphere method. The obtained ammonium polyphosphate is first dry-mixed and pre-dispersed with melamine, alcohol compounds, etc., and then melt-blended by screw extruder; then melt-sheared at a certain temperature, and then granulated to obtain the second material layer 42.

[0158] For example, when manufacturing the third material layer 43, a composite of expanded graphite and montmorillonite as synergists is used. First, the expanded graphite needs to be functionalized, mainly through oxidation and layer expansion treatment, introducing carboxyl or epoxy groups to enhance the bonding force with the polymer interface. Then, the montmorillonite also needs to undergo corresponding nano-modification, such as by adding a surfactant and stirring thoroughly in the liquid phase to expand the interlayer spacing. Afterward, the modified montmorillonite and expanded graphite are added separately using the sol-gel method, stirred thoroughly, and allowed to stand to obtain a gel. Then, heat treatment is performed to obtain the third material layer 43.

[0159] According to a second aspect of this disclosure, a battery pack is provided, which includes the aforementioned battery cell 21. This battery pack possesses all the beneficial effects of the aforementioned battery cell 21, which will not be repeated here. In this embodiment, the same reference numerals represent the same elements having similar functions, and will not be described further.

[0160] Reference Figure 5This disclosure provides a battery pack, including a housing 1, a battery assembly, a pressure relief valve 3, and a flame-retardant layer 4.

[0161] In some embodiments, the housing 1 has a mounting cavity 13.

[0162] In this embodiment, the housing 1 can prevent liquids or other foreign objects from affecting the charging or discharging of the battery cell 21.

[0163] The box 1 can be a simple three-dimensional structure such as a cuboid, cylinder, or sphere, or it can be a complex three-dimensional structure composed of simple three-dimensional structures such as cuboids, cylinders, or spheres. The embodiments of this application do not limit this.

[0164] The material of the housing 1 can be an alloy material such as aluminum alloy or iron alloy, or a polymer material such as polycarbonate or polyisocyanurate foam, or a composite material such as glass fiber and epoxy resin. This application embodiment is not limited to this.

[0165] In some embodiments, the battery assembly is located within the mounting cavity 13.

[0166] In this embodiment, the battery assembly is disposed within the mounting cavity 13, which can prevent the battery assembly from being affected by the external environment and ensure that the battery assembly works normally.

[0167] In some embodiments, the pressure relief valve 3 may be selectively connected to the mounting cavity 13.

[0168] In this embodiment, the pressure relief valve 3 can be used to release the internal gas of the housing 1 (e.g., the mounting cavity 13).

[0169] As an example, the internal pressure or temperature of the housing 1 is actuated to release the internal pressure or temperature when it reaches a predetermined threshold. When the internal pressure or temperature of the housing 1 reaches the predetermined threshold, the pressure relief valve 3 performs an action or a weak structure provided in the pressure relief valve 3 is destroyed, thereby forming an opening or channel for the release of internal pressure or temperature.

[0170] In this embodiment, a gap can be provided between the battery assembly and the housing 1. This gap can serve as a pressure relief channel. When the battery pack experiences thermal runaway, the discharge material far from the pressure relief valve 3 can flow from the pressure relief channel to the pressure relief valve 3.

[0171] In some embodiments, the flame-retardant layer 4 is disposed in at least one of the housing 1, the battery assembly, and the pressure relief valve 3.

[0172] In this embodiment, a flame-retardant layer 4 is provided on at least one of the housing 1, the battery assembly, and the pressure relief valve 3. The flame-retardant layer 4 expands in volume when the temperature exceeds a preset value, thereby suppressing the outward thermal diffusion after the battery pack experiences thermal runaway, making it less likely for the battery pack to catch fire or explode after thermal runaway.

[0173] In some embodiments, the housing 1 includes a base 11 and a cover 12, which together form a mounting cavity 13. In this embodiment, the base 11 is an open structure with an opening on one side, and the cover 12 covers the opening of the base 11 to form a sealed connection, thereby forming a closed mounting cavity 13. When the base 11 and the cover 12 are connected to each other, the mating area between the base 11 and the cover 12 can also be sealed to improve the sealing performance of the mounting cavity 13.

[0174] In some embodiments, a flame-retardant layer 4 is disposed on at least one surface of the lid 12, and / or the flame-retardant layer 4 is disposed inside the lid 12, and / or the flame-retardant layer 4 includes at least two material layers and an adhesive layer 44 connecting adjacent material layers, and the flame-retardant layer 4 is disposed on at least one surface of the lid 12.

[0175] In this embodiment, a flame-retardant layer 4 is disposed on the box cover 12. The flame-retardant layer 4 expands and enlarges when the temperature exceeds a preset value, thereby blocking or preventing the ejected material from being ejected outward along the box cover 12, so as to suppress heat diffusion, as well as suppress arcing and the diffusion of smoke, and effectively protect the box cover 12.

[0176] In this embodiment, the flame-retardant layer 4 in the form of a coating can be disposed on at least one surface of the lid 12. For example, the flame-retardant layer 4 can be disposed on the inner surface of the lid 12 facing the mounting cavity 13 or on the outer surface of the lid 12 away from the mounting cavity 13, or the flame-retardant layer 4 can be disposed on both the inner and outer surfaces of the lid 12.

[0177] In this embodiment, the flame-retardant layer 4 in the form of a sandwich structure can be disposed inside the lid 12, that is, between the inner surface and the outer surface of the lid 12. When the flame-retardant layer 4 expands, it can force the inner and outer surfaces of the lid 12 to deform or crack, thereby suppressing arcing and the diffusion of smoke.

[0178] In this embodiment, compared to the flame retardant layer 4 in the form of a coating, the flame retardant layer 4 in the form of a sandwich is placed inside the box cover 12, so that the flame retardant layer 4 needs to be at a higher external temperature to reach the preset temperature and expand.

[0179] In this embodiment, the flame-retardant layer 4 in the form of a sandwich is disposed inside the cover 12, which can improve the explosion resistance of the cover 12 and reduce the weight of the cover 12.

[0180] In this embodiment, the composite flame-retardant layer 4 can be disposed on at least one surface of the lid 12. For example, the flame-retardant layer 4 can be disposed on the inner surface of the lid 12 (e.g., Figure 5 The flame-retardant layer 4 may be provided on the outer surface of the lid 12, or on both the inner and outer surfaces of the lid 12.

[0181] In this embodiment, the flame-retardant layer 4 is constructed by stacking or combining multiple material layers, which can achieve functional integration. For example, when the flame-retardant layer 4 is constructed by stacking or combining a first material layer 41 and a second material layer 42, it can simultaneously achieve the functions of heat insulation and smoke suppression, thus achieving functional integration.

[0182] In this embodiment, the composite flame-retardant layer 4, compared to a single-layer flame-retardant layer 4, can simultaneously achieve both mechanical and flame-retardant properties, ensuring good strength while improving its flame-retardant safety. Furthermore, it enhances the durability of the flame-retardant layer 4 when providing safety protection.

[0183] In some embodiments, the housing 1 includes a central channel 14 disposed within the mounting cavity 13 and a fireproof cover disposed within the central channel 14.

[0184] In this embodiment, the central channel 14 is connected to the housing 11, which can improve the structural strength of the housing 1, such as increasing the overall torsional stiffness of the battery pack and resisting bending stress during vehicle operation. The central channel 14 adopts a hollow structure and runs through the housing 11 along the length or width of the battery pack, which can prevent the internal pressure relief flow path from being blocked after the housing 1 is deformed.

[0185] In this embodiment, cooling pipes and / or high-voltage wiring harnesses can also be installed inside the central channel 14 to facilitate the arrangement of cooling pipes and high-voltage wiring harnesses.

[0186] In this embodiment, the central channel 14 can be made of metal, and the fireproof cover can be made of insulating material (such as plastic). Placing the fireproof cover on the central channel 14 can provide insulation protection for the central channel 14.

[0187] In some embodiments, the flame-retardant layer 4 is disposed on at least one surface of the fireproof cover, and / or the flame-retardant layer 4 is disposed inside the fireproof cover.

[0188] In this embodiment, the flame-retardant layer 4 is disposed on the fireproof cover. The flame-retardant layer 4 expands and enlarges when the temperature exceeds the preset value, thereby blocking or preventing the ejected material from being ejected outward along the fireproof cover (i.e., the central channel 14) to suppress heat diffusion and smoke diffusion, thus providing effective protection for the fireproof cover.

[0189] In this embodiment, the flame-retardant layer 4 in the form of a coating can be disposed on at least one surface of the fireproof cover. For example, the flame-retardant layer 4 can be disposed on the inner surface of the fireproof cover facing the central channel 14 or on the outer surface of the fireproof cover away from the central channel 14, or the flame-retardant layer 4 can be disposed on both the inner and outer surfaces of the fireproof cover.

[0190] In this embodiment, the flame-retardant layer 4 in the form of a sandwich structure can be disposed inside the fireproof cover, that is, between the inner and outer surfaces of the fireproof cover. When the flame-retardant layer 4 expands, it can force the inner and outer surfaces of the fireproof cover to deform or crack, thereby inhibiting the diffusion of heat and smoke.

[0191] In this embodiment, compared to the flame-retardant layer 4 in the form of a coating, the flame-retardant layer 4 in the form of a sandwich is placed inside the fireproof cover, so that the flame-retardant layer 4 needs to be at a higher external temperature to reach the preset temperature and expand.

[0192] In this embodiment, the flame-retardant layer 4 in the form of a sandwich is disposed inside the fireproof cover, which can improve the explosion resistance performance of the fireproof cover.

[0193] In some embodiments, housing 1 includes a fireproof blanket covering the battery assembly.

[0194] In this embodiment, a fire blanket covers the top of the battery assembly and is located at the bottom of the cover 12, which can delay the flames from burning through the cover 12. The top of the fire blanket is spaced apart from the cover 12 to avoid obstructing the pressure relief valve 3 from releasing pressure. The fire blanket can be made of insulating material.

[0195] In some embodiments, the flame-retardant layer 4 is disposed on at least one surface of the fire blanket, and / or the flame-retardant layer 4 is disposed inside the fire blanket, and / or the flame-retardant layer 4 includes at least two material layers and an adhesive layer 44, and the flame-retardant layer 4 is disposed on at least one surface of the fire blanket.

[0196] In this embodiment, a flame-retardant layer 4 is disposed on the fire blanket. The flame-retardant layer 4 expands and enlarges when the temperature exceeds a preset value, thereby blocking or preventing the ejected material from being ejected outward along the fire blanket, thus suppressing heat diffusion and smoke diffusion, and effectively protecting the fire blanket.

[0197] In this embodiment, the flame-retardant layer 4 in the form of a coating can be disposed on at least one surface of the fire blanket. For example, the flame-retardant layer 4 can be disposed on the inner surface of the fire blanket facing the battery assembly or on the outer surface of the fire blanket away from the battery assembly, or the flame-retardant layer 4 can be disposed on both the inner and outer surfaces of the fire blanket.

[0198] In this embodiment, the flame-retardant layer 4 in the form of a sandwich structure can be disposed inside the fire blanket, that is, between the inner and outer surfaces of the fire blanket. When the flame-retardant layer 4 expands, it can force the inner and outer surfaces of the fire blanket to deform or crack, thereby suppressing arcing and the spread of smoke.

[0199] In this embodiment, compared to the coating-type flame retardant layer 4, the sandwich-type flame retardant layer 4, after being placed inside the fire blanket, requires a higher external temperature to reach the preset temperature and expand.

[0200] In this embodiment, the composite flame-retardant layer 4 can be disposed on at least one surface of the fire blanket. For example, the flame-retardant layer 4 can be disposed on the inner surface of the fire blanket or the outer surface of the cover 12, or the flame-retardant layer 4 can be disposed on both the inner and outer surfaces of the fire blanket.

[0201] In this embodiment, the flame-retardant layer 4 is constructed by stacking or combining multiple material layers, which can achieve functional integration. For example, when the flame-retardant layer 4 is constructed by stacking or combining a first material layer 41 and a second material layer 42, it can simultaneously achieve the functions of heat insulation and smoke suppression, thus achieving functional integration.

[0202] In this embodiment, the composite flame-retardant layer 4, compared to a single-layer flame-retardant layer 4, can simultaneously achieve both mechanical and flame-retardant properties, ensuring good strength while improving its flame-retardant safety. Furthermore, it enhances the durability of the flame-retardant layer 4 when providing safety protection.

[0203] In some embodiments, the battery assembly includes a plurality of battery modules 2.

[0204] In this embodiment, the battery module 2 includes at least one battery cell 21. Multiple battery cells 21 can be connected in series, parallel, or a combination thereof; a combination of series and parallel connections refers to a mix of both.

[0205] In the embodiments of this application, multiple battery cells 21 can be directly assembled into a battery module or battery pack, or they can be first assembled into a battery module 2, and then the battery module 2 can be assembled into a battery module or battery pack.

[0206] In some embodiments, the battery module 2 has electrode plates.

[0207] In this embodiment, the battery module 2 has a positive electrode plate and a negative electrode plate. The battery modules 2 are connected in series, in parallel or in a mixed manner by means of the electrical connection between the electrode plates.

[0208] In some embodiments, the flame retardant layer 4 is disposed on at least one surface of the electrode sheet, and / or the flame retardant layer 4 is disposed within the electrode sheet, and / or the flame retardant layer 4 includes at least two material layers and an adhesive layer 44, and the flame retardant layer 4 is disposed on at least one surface of the electrode sheet.

[0209] In this embodiment, a flame-retardant layer 4 is disposed on the electrode sheet. The flame-retardant layer 4 expands and enlarges when the temperature exceeds a preset value, thereby blocking or preventing the ejected material from being ejected outward along the electrode sheet, thus suppressing heat diffusion, arcing, and the diffusion of smoke, and providing effective protection for the electrode sheet.

[0210] In this embodiment, the flame-retardant layer 4 in the form of a coating can be disposed on at least one surface of the electrode sheet. For example, the flame-retardant layer 4 can be disposed on the inner surface of the electrode sheet facing the battery cell 21 or on the outer surface of the electrode sheet away from the battery cell 21, or the flame-retardant layer 4 can be disposed on both the inner and outer surfaces of the electrode sheet.

[0211] In this embodiment, the flame-retardant layer 4 in the form of a sandwich structure can be disposed within the electrode sheet, that is, between the inner and outer surfaces of the electrode sheet. When the flame-retardant layer 4 expands, it can force the inner and outer surfaces of the electrode sheet to deform or crack, thereby suppressing arcing and the diffusion of smoke.

[0212] In this embodiment, compared to the flame retardant layer 4 in the form of a coating, the flame retardant layer 4 in the form of a sandwich is disposed inside the electrode sheet, so that the flame retardant layer 4 needs to be at a higher external temperature to reach the preset temperature and expand.

[0213] In this embodiment, the flame-retardant layer 4 in the form of a sandwich is disposed inside the electrode sheet, which can improve the blast resistance performance of the electrode sheet.

[0214] In this embodiment, the composite flame-retardant layer 4 can be disposed on at least one surface of the electrode sheet. For example, the flame-retardant layer 4 can be disposed on the inner surface of the electrode sheet or the outer surface of the cover 12, or the flame-retardant layer 4 can be disposed on both the inner and outer surfaces of the electrode sheet.

[0215] In this embodiment, the flame-retardant layer 4 is constructed by stacking or combining multiple material layers, which can achieve functional integration. For example, when the flame-retardant layer 4 is constructed by stacking or combining a first material layer 41 and a second material layer 42, it can simultaneously achieve the functions of heat insulation and smoke suppression, thus achieving functional integration.

[0216] In this embodiment, the composite flame-retardant layer 4, compared to a single-layer flame-retardant layer 4, can simultaneously achieve both mechanical and flame-retardant properties, ensuring good strength while improving its flame-retardant safety. Furthermore, it enhances the durability of the flame-retardant layer 4 when providing safety protection.

[0217] In other embodiments, considering the high voltage at the terminals (e.g., positive and negative terminals) of the battery pack and the high necessity for protection, in order to further improve the safety performance of the battery pack, a flame-retardant layer 4 may be disposed on at least one surface of the terminal, and / or the flame-retardant layer 4 may be disposed inside the terminal, and / or the flame-retardant layer 4 may include at least two material layers and an adhesive layer 44, with the flame-retardant layer 4 disposed on at least one surface of the terminal.

[0218] In some embodiments, the battery assembly includes a battery plate electrically connected to the battery module 2 and a protective cover disposed on the battery plate.

[0219] In this embodiment, the electrode pads are made of conductive materials, and the battery pack terminals and the module electrode pads are usually electrically connected through the electrode pads.

[0220] In this embodiment, the bar sheet can be made of metal, and the protective cover can be made of insulating material (such as plastic). Placing the protective cover on the bar sheet can provide insulation protection for the bar sheet.

[0221] In some embodiments, the flame-retardant layer 4 is disposed on at least one surface of the protective cover, and / or the flame-retardant layer 4 is disposed inside the protective cover, and / or the flame-retardant layer 4 includes at least two material layers and an adhesive layer 44, and the flame-retardant layer 4 is disposed on at least one surface of the protective cover.

[0222] In this embodiment, a flame-retardant layer 4 is disposed on the protective cover. The flame-retardant layer 4 expands and enlarges when the temperature exceeds a preset value, thereby blocking or preventing the ejected material from being ejected outward along the protective cover, thus suppressing heat diffusion, arcing, and the diffusion of smoke, and effectively protecting the cover 12.

[0223] In this embodiment, the flame-retardant layer 4 in the form of a coating can be disposed on at least one surface of the protective cover. For example, the flame-retardant layer 4 can be disposed on the inner surface of the protective cover facing the bar sheet or on the outer surface of the protective cover away from the bar sheet, or the flame-retardant layer 4 can be disposed on both the inner and outer surfaces of the protective cover.

[0224] In this embodiment, the flame-retardant layer 4 in the form of a sandwich structure can be disposed inside the protective cover, that is, between the inner and outer surfaces of the protective cover. When the flame-retardant layer 4 expands, it can force the inner and outer surfaces of the protective cover to deform or crack, thereby suppressing arcing and the spread of smoke.

[0225] In this embodiment, compared to the flame-retardant layer 4 in the form of a coating, the flame-retardant layer 4 in the form of a sandwich is placed inside the protective cover, so that the flame-retardant layer 4 needs to be at a higher external temperature to reach the preset temperature and expand.

[0226] In this embodiment, the flame-retardant layer 4 in the form of a sandwich is disposed inside the protective cover, which can improve the explosion resistance performance of the protective cover.

[0227] In this embodiment, the composite flame-retardant layer 4 can be disposed on at least one surface of the protective cover. For example, the flame-retardant layer 4 can be disposed on the inner surface or the outer surface of the protective cover, or the flame-retardant layer 4 can be disposed on both the inner and outer surfaces of the protective cover.

[0228] In this embodiment, the flame-retardant layer 4 is constructed by stacking or combining multiple material layers, which can achieve functional integration. For example, when the flame-retardant layer 4 is constructed by stacking or combining a first material layer 41 and a second material layer 42, it can simultaneously achieve the functions of heat insulation and smoke suppression, thus achieving functional integration.

[0229] In this embodiment, the composite flame-retardant layer 4, compared to a single-layer flame-retardant layer 4, can simultaneously achieve both mechanical and flame-retardant properties, ensuring good strength while improving its flame-retardant safety. Furthermore, it enhances the durability of the flame-retardant layer 4 when providing safety protection.

[0230] In some embodiments, the pressure relief valve 3 includes a valve seat disposed on the housing cover 12 and a valve plate that cooperates with the valve seat.

[0231] In this embodiment, a valve seat is disposed on the cover 12, and a pressure relief passage is formed inside the valve seat. When the internal pressure or temperature of the battery pack reaches a critical value, at least a portion of the valve plate ruptures, breaks, is torn, or opens to open the pressure relief passage and ensure the safety of the battery pack. When the valve plate is not ruptured, it blocks the pressure relief passage to prevent the mounting cavity 13 from communicating with the outside through the pressure relief passage.

[0232] In some embodiments, the flame retardant layer 4 is disposed on at least one surface of the valve plate, and / or the flame retardant layer 4 is disposed within the valve plate, and / or the flame retardant layer 4 includes at least two material layers and an adhesive layer 44, and the flame retardant layer 4 is disposed on at least one surface of the valve seat and / or the valve plate.

[0233] In this embodiment, a flame-retardant layer 4 is disposed on the valve plate. The flame-retardant layer 4 expands and enlarges when the temperature exceeds a preset value, thereby blocking or preventing the ejected material from being ejected outward along the valve plate (for example, when a small amount of ejected material is ejected), so as to suppress heat diffusion, as well as arcing and smoke diffusion, and effectively protect the valve plate.

[0234] In this embodiment, the flame-retardant layer 4 in the form of a coating can be disposed on at least one surface of the valve plate. For example, the flame-retardant layer 4 can be disposed on the inner surface of the valve plate facing the mounting cavity 13 or on the outer surface of the valve plate away from the mounting cavity 13, or the flame-retardant layer 4 can be disposed on both the inner and outer surfaces of the valve plate.

[0235] In this embodiment, the flame-retardant layer 4 in the form of a sandwich structure can be disposed within the valve plate, that is, between the inner and outer surfaces of the valve plate. When the flame-retardant layer 4 expands, it can force the inner and outer surfaces of the valve plate to deform or crack, thereby suppressing arcing and the diffusion of smoke.

[0236] In this embodiment, compared to the flame retardant layer 4 in the form of a coating, the flame retardant layer 4 in the form of a sandwich is disposed inside the valve plate, so that the flame retardant layer 4 needs to be at a higher external temperature to reach the preset temperature and expand.

[0237] In this embodiment, the flame-retardant layer 4 in the form of a sandwich is disposed inside the valve plate, which can improve the valve plate's resistance to blasting.

[0238] In this embodiment, the composite flame-retardant layer 4 can be disposed on at least one surface of the valve seat and / or valve plate. For example, the flame-retardant layer 4 can be disposed on the inner surface of the valve seat and / or valve plate or the outer surface of the valve seat and / or valve plate, or the flame-retardant layer 4 can be disposed on both the inner and outer surfaces of the valve seat and / or valve plate.

[0239] In this embodiment, the flame-retardant layer 4 is constructed by stacking or combining multiple material layers, which can achieve functional integration. For example, when the flame-retardant layer 4 is constructed by stacking or combining a first material layer 41 and a second material layer 42, it can simultaneously achieve the functions of heat insulation and smoke suppression, thus achieving functional integration.

[0240] In this embodiment, the composite flame-retardant layer 4, compared to a single-layer flame-retardant layer 4, can simultaneously achieve both mechanical and flame-retardant properties, ensuring good strength while improving its flame-retardant safety. Furthermore, it enhances the durability of the flame-retardant layer 4 when providing safety protection.

[0241] In this embodiment, when the battery pack experiences thermal runaway, the ejected airflow is mainly discharged through the pressure relief valve 3. Compared to the solution of "setting the flame-retardant layer 4 on the cover 12", setting the flame-retardant layer 4 on the pressure relief valve 3 (e.g., explosion-proof plate and / or valve seat) can more directly suppress thermal runaway.

[0242] In the description of this application, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more features. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0243] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0244] The embodiments, implementation methods, and related technical features of this application can be combined and substituted for each other without conflict.

[0245] The above are merely preferred embodiments of this application and are not intended to limit this application in any way. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of this application without departing from the scope of the technical solution of this application shall still fall within the scope of the technical solution of this application.

Claims

1. A battery pack, characterized in that, include: The enclosure has a mounting cavity; A battery assembly located within a mounting cavity; A pressure relief valve, which may be connected to the mounting cavity; A flame-retardant layer that expands when a preset temperature is exceeded, and the flame-retardant layer is disposed in at least one of the housing, battery assembly and pressure relief valve; The flame-retardant layer includes at least one of a first material layer, a second material layer, and a third material layer. The first material layer includes expanded graphite and inorganic fillers. The second material layer includes ammonium polyphosphate, melamine, and alcohol compounds. The third material layer includes expanded graphite and a synergist.

2. The battery pack as described in claim 1, characterized in that, The enclosure includes a base and a cover, the base and cover forming a mounting cavity, and the flame-retardant layer is disposed on at least one surface of the cover; and / or, The flame-retardant layer is disposed inside the box lid; and / or, The flame-retardant layer comprises at least two material layers and an adhesive layer connecting adjacent material layers, and the flame-retardant layer is disposed on at least one surface of the lid.

3. The battery pack as described in claim 1, characterized in that, The enclosure includes a central channel disposed within the mounting cavity and a fireproof cover disposed within the central channel, wherein the flame-retardant layer is disposed on at least one surface of the fireproof cover; and / or, The flame-retardant layer is disposed inside the fireproof cover.

4. The battery pack as described in claim 1, characterized in that, The enclosure includes a fireproof blanket covering the battery assembly, and the flame-retardant layer is disposed on at least one surface of the fireproof blanket; and / or, The flame-retardant layer is disposed within the fireproof blanket; and / or, The flame-retardant layer comprises at least two material layers and an adhesive layer, and the flame-retardant layer is disposed on at least one surface of the fire blanket.

5. The battery pack as described in claim 1, characterized in that, The battery assembly includes multiple battery modules, each battery module having electrode plates, and the flame-retardant layer is disposed on at least one surface of the electrode plates; and / or, The flame-retardant layer is disposed within the electrode sheet; and / or, The flame-retardant layer comprises at least two material layers and an adhesive layer, and the flame-retardant layer is disposed on at least one surface of the electrode sheet.

6. The battery pack as described in claim 1, characterized in that, The battery assembly includes multiple battery modules, a switch electrically connected to the battery modules, and a protective cover disposed on the switch; the flame-retardant layer is disposed on at least one surface of the protective cover; and / or, The flame-retardant layer is disposed inside the protective cover; and / or, The flame-retardant layer comprises at least two material layers and an adhesive layer, and the flame-retardant layer is disposed on at least one surface of the protective cover.

7. The battery pack as claimed in claim 1, characterized in that, The pressure relief valve includes a valve seat disposed on the tank cover and a valve plate cooperating with the valve seat, wherein the flame-retardant layer is disposed on at least one surface of the valve plate; and / or, The flame-retardant layer is disposed within the valve plate; and / or, The flame-retardant layer comprises at least two material layers and an adhesive layer, and the flame-retardant layer is disposed on at least one surface of the valve seat and / or valve plate.

8. The battery pack as described in claim 1, characterized in that, The thickness of the first material layer is between 1 mm and 2 mm, the thickness of the second material layer is between 1 mm and 3 mm, and the thickness of the third material layer is between 10 μm and 200 μm; The density of the first material layer is between 1.2 g / cm³. 3 Up to 1.8 g / cm 3 The density of the second material layer is between 1.0 g / cm³. 3 Up to 1.5g / cm 3 The density of the third material layer is between 1.1 g / cm³. 3 Up to 1.6 g / cm 3 between; The expansion ratio of the first material layer is between 10 and 200 times, the expansion ratio of the second material layer is between 10 and 30 times, and the expansion ratio of the third material layer is between 5 and 15 times.

9. The battery pack as claimed in claim 1, characterized in that, In the first material layer, the mass percentage of expanded graphite is 10% to 30%; In the second material layer, the mass percentage of ammonium polyphosphate is 20% to 30%, and the mass percentage of melamine is 15% to 20%. In the third material layer, the synergist is selected from at least one of montmorillonite, zeolite, and boron-containing compounds.

10. The battery pack as claimed in claim 1, characterized in that, The battery assembly includes a battery module, the battery module including at least one battery cell, the battery cell comprising: A housing includes a housing base and a housing cover, the housing base and the housing cover together forming a receiving cavity, the housing cover having a first surface facing away from the receiving cavity and a second surface facing the receiving cavity; An electrode assembly located within a receiving cavity; An explosion-proof valve, which may be selectively connected to a receiving cavity; Wherein, the flame-retardant layer is disposed on the first surface; and / or, The flame-retardant layer is disposed between the first surface and the second surface; and / or, The flame-retardant layer is disposed on the explosion-proof valve.

Images