Thermal diffusion inhibition type composite battery pack

Abstract

The invention relates to the technical field of batteries, in particular to a thermal diffusion inhibition type composite battery pack. Comprising a battery array, a shell, first heat preservation foam, second heat preservation foam and a safety seam, and the battery array comprises a plurality of single batteries; one phase change sheet is arranged between every two single batteries to form a combined body; the elastic foam is arranged between the adjacent combination bodies; the thermal diffusion suppression plate is arranged right above the battery array; the middle part of the first thermal insulation foam is attached to the first side surface of the battery array, and two end parts extending from the middle part respectively cover at least one part of the upper end surface and the lower end surface of the battery array; the middle part of the second heat preservation foam is attached to the second side face of the battery array, and the two end parts extending out of the middle part respectively cover the upper end face and the lower end face of at least one part of the battery array and are overlapped above or below the first heat preservation foam in a staggered mode. According to the invention, the diffusion time of thermal runaway of the battery is greatly prolonged, and the safety of passengers is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and particularly to a composite battery pack with thermal diffusion suppression. Background Art

[0002] With the large-screen and multi-functionalization of digital terminal products and the popularization of new energy vehicles, traditional graphite anode batteries have gradually been unable to meet the market requirements for battery endurance, charging speed, and safety. With the gradual maturity of soft-pack battery technology, silicon-carbon secondary batteries can achieve high specific energy, and the specific energy is as high as more than 400 Wh / kg, having great application value in the field of high specific energy. However, the reaction of silicon combined with lithium will cause a sharp increase in the thickness of the monomer, resulting in huge deformation of the module structure parts.

[0003] Currently, the conventional method to solve battery swelling is to use a splint and a high-density foam composite distributed on both sides of the battery stack to limit the excessive deformation of the monomer, which will cause a huge extrusion force between the monomers, easily causing monomer damage, and this method cannot solve the problem of thermal diffusion caused by thermal runaway of the battery, thus easily triggering a chain reaction.

[0004] In the prior art, Chinese Patent Application CN113594583A discloses a thermal management system for a lithium-ion battery pack to suppress thermal runaway propagation, which uses a phase change material to absorb heat from the monomer battery, a heat dissipation fin for heat dissipation, and an aerogel plate for heat insulation to achieve the suppression of thermal runaway propagation. This method only suppresses thermal runaway by heat absorption and heat insulation, and cannot effectively solve the battery swelling problem and cannot effectively prevent the chain reaction of thermal runaway; Chinese Patent Application CN118137015A discloses a vehicle battery cooling and thermal runaway suppression coupling system, which uses the vaporization of a fluorinated liquid to absorb heat and block air to achieve thermal runaway suppression. This method relies on external cooling, the system structure is complex, and it also cannot effectively solve the battery swelling problem, and the thermal runaway suppression effect is limited. Summary of the Invention

[0005] The purpose of the present invention is to provide a composite battery pack with thermal diffusion suppression, a housing, a first heat-insulating foam, a second heat-insulating foam, and a safety seam to solve the above technical problems;

[0006] The technical problems solved by the present invention can be realized by adopting the following technical solutions:

[0007] A composite battery pack with thermal diffusion suppression, comprising a battery array, and the battery array includes

[0008] a plurality of monomer batteries arranged in an array in a preset series-parallel manner;

[0009] A phase change sheet, with one such phase change sheet provided between every two of the monomer cells to form an assembly;

[0010] An elastic foam, provided between adjacent ones of the assemblies;

[0011] A heat diffusion suppression plate, provided directly above the battery array, for releasing a flame retardant upon being heated and ruptured when a monomer cell undergoes thermal runaway; the first heat insulation foam and the second heat insulation foam are wrapped around the outside of the battery array;

[0012] The middle part of the first heat insulation foam is attached to the first side surface of the battery array, and the two end parts extending from the middle part of the first heat insulation foam respectively cover at least a part of the upper end surface and the lower end surface of the battery array; the middle part of the second heat insulation foam is attached to the second side surface of the battery array, and the two end parts extending from the middle part of the second heat insulation foam respectively cover at least a part of the upper end surface and the lower end surface of the battery array, and are staggeredly stacked above or below the first heat insulation foam.

[0013] Preferably, a flame retardant coating layer is provided on the microscopic surface of the sponge matrix of the elastic foam, the first heat insulation foam, and the second heat insulation foam.

[0014] Preferably, the elastic foam, the first heat insulation foam, and the second heat insulation foam are open-cell foams made of melamine, with a density of 8 kg / m 3 ~50 kg / m 3 。

[0015] Preferably, the battery array further includes end plates, located at both ends of the battery array, for protecting the monomer cells at the ends.

[0016] Preferably, the end plates are rigid foams, with a density of 50 kg / m 3 ~200 kg / m 3 。

[0017] Preferably, the heat diffusion suppression plate is a perfluoropentanone nano-microcapsule plate, the perfluoropentanone nano-microcapsule plate includes a plurality of nano-scale microcapsules, each of the microcapsules encapsulates the flame retardant inside, and the outside of the microcapsule is a thermal-sensitive layer that wraps the flame retardant.

[0018] Preferably, the battery array is provided inside the housing, and a breakable safety seam is provided in the exact middle of the housing.

[0019] Preferably, the elastic foam is in a compressed state. When the monomer cell is in a discharged state, the compression ratio of the elastic foam is 40% - 50%, and when the monomer cell is in a fully charged state, the compression ratio of the elastic foam is 50% - 95%.

[0020] Preferably, the density of the phase change sheet is 1000 kg / m 3 ~1500 kg / m 3 , and the phase change temperature is 52 °C to 60 °C.

[0021] Advantages of the present invention: Due to the above technical solutions, the present invention greatly extends the diffusion time of battery thermal runaway and improves the safety of passengers through the phase change sheet, the heat diffusion suppression plate and the elastic foam. Description of the Drawings

[0022] Figure 1 Schematic diagram of the composition of the heat diffusion suppression type composite battery pack in the embodiment of the present invention;

[0023] Figure 2 Top view of the heat diffusion suppression type composite battery pack in the embodiment of the present invention;

[0024] Figure 3 Schematic diagram of the composition of the monomer battery and the phase change sheet composite in the embodiment of the present invention.

[0025] In the drawings: 1, monomer battery; 2, phase change sheet; 3, elastic foam; 4, end plate; 5, outer shell; 6, first heat preservation foam; 7, second heat preservation foam; 8, heat diffusion suppression plate; 9, safety seam. Detailed Embodiments

[0026] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0027] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments may be combined with each other.

[0028] The following further describes the present invention with reference to the drawings and specific embodiments, but does not limit the present invention.

[0029] A heat diffusion suppression type composite battery pack, as Figures 1 to 3 shown, includes a battery array, an outer shell 5, a first heat preservation foam 6, a second heat preservation foam 7 and a safety seam 9. The battery array includes,

[0030] a plurality of monomer batteries 1 arranged in an array in a preset series-parallel manner;

[0031] a phase change sheet 2, and a phase change sheet 2 is provided between every two monomer batteries 1 to form a combination;

[0032] The elastic foam 3 is disposed between adjacent assemblies.

[0033] The heat diffusion suppression plate 8 is disposed directly above the battery array and is used to release a flame retardant when broken by heat during thermal runaway of the single battery 1.

[0034] The first heat preservation foam 6 and the second heat preservation foam 7 are wrapped around the outside of the battery array.

[0035] The middle part of the first heat preservation foam 6 is attached to the first side surface of the battery array, and the two ends extending from the middle part of the first heat preservation foam 6 respectively cover at least a part of the upper end surface and the lower end surface of the battery array; the middle part of the second heat preservation foam 7 is attached to the second side surface of the battery array, and the two ends extending from the middle part of the second heat preservation foam 7 respectively cover at least a part of the upper end surface and the lower end surface of the battery array, and are staggeredly stacked above or below the first heat preservation foam 6.

[0036] Specifically, in view of the problems of over-expansion during charge and discharge and thermal runaway of high-expansion-rate batteries such as silicon-carbon secondary batteries in the prior art, the present invention proposes a composite battery pack with a flame retardant effect and avoiding excessive expansion, achieving the technical effect of delaying the spread time of thermal runaway and extending the escape time of passengers.

[0037] The single battery 1 of the present invention is a high-expansion-rate lithium-ion battery single, and a plurality of single batteries 1 are arranged in an array in a specified series-parallel connection manner.

[0038] The phase change sheet 2 can absorb heat through solid-liquid phase change, and its density is 1000 kg / m 3 ~1500 kg / m 3 , the phase change temperature is between 52 °C and 60 °C, and a phase change sheet 2 is installed between every two single batteries 1, and a combination body composed of two single batteries 1 and the phase change sheet 2.

[0039] More specifically, the first heat preservation foam 6 and the second heat preservation foam 7 form a staggered stacking area in the middle of the upper end surface and the middle of the lower end surface of the battery array, and the stacking area is only in a slidable contact relationship. Specifically, when thermal runaway occurs in the single battery 1, the volume of the single battery 1 expands rapidly, and the adjacent single batteries 1 are pushed towards the two end plates 4. When the thrust received by the outer shell 5 ≥ 200 kg, it breaks at the safety seam 9, and the first heat preservation foam 6 and the second heat preservation foam 7 are displaced towards the two end plates 4 respectively, and the overlapping position can still block the spread of thermal runaway from the safety seam 9 position, and the length of the overlapping area accounts for 50% - 100% of the length of the battery pack.

[0040] In the present invention, the first heat preservation foam 6, the second heat preservation foam 7 and the heat diffusion suppression plate 8 cooperate with each other, greatly extending the diffusion time of battery thermal runaway and improving the safety of passengers.

[0041] The first heat-insulating foam 6 and the second heat-insulating foam 7 are installed in the space between the housing 5 and the battery array formed by the single cell 1, the phase change sheet 2, the elastic foam 3, and the end plate 4. Specifically, the first heat-insulating foam 6 and the second heat-insulating foam 7 are located inside the housing 5 and wrap the outside of the battery array.

[0042] In the middle of the battery array, the first heat-insulating foam 6 and the second heat-insulating foam 7 form an interleaved and superimposed area, and the superimposed area has only a slidable relationship of contact.

[0043] In a preferred embodiment, the sponge matrix micro-surfaces of the elastic foam 3, the first heat-insulating foam 6, and the second heat-insulating foam 7 are provided with a flame retardant coating layer.

[0044] Specifically, the first heat-insulating foam 6 and the second heat-insulating foam 7 are used for heat insulation and heat preservation, preventing the heat inside the battery pack from diffusing outward, and at the same time, it can also avoid the influence of the external environmental temperature on the battery pack. The surface of the heat-insulating foam has a flame retardant coating layer, which can play a flame retardant role when the battery has a thermal runaway, preventing the spread of fire.

[0045] When the battery pack has a thermal runaway, the housing 5 disconnects at the safety seam 9, and the first heat-insulating foam 6 and the second heat-insulating foam 7 will displace in the direction of the two end plates 4 respectively. The overlapping position can still block the spread of the thermal runaway from the safety seam 9 position, further delaying the spread speed of the thermal runaway.

[0046] Immerse the elastic foam 3, the first heat-insulating foam 6, and the second heat-insulating foam 7 in a solvent containing 1% - 5% inhibitor and soak them sufficiently. After taking out the elastic foam 3, the first heat-insulating foam 6, and the second heat-insulating foam 7, perform a drying treatment, and a flame retardant coating layer is naturally deposited on the surface of the sponge matrix of the elastic foam 3, the first heat-insulating foam 6, and the second heat-insulating foam 7.

[0047] The inhibitor used in the present invention is a nitrogen-phosphorus type inhibitor, and its main components are carbamate, melamine, etc. This inhibitor can play a role by inhibiting fuel and inhibiting heating. They can form a layer of flame retardant coating layer on the surfaces of the elastic foam 3, the first heat-insulating foam 6, and the second heat-insulating foam 7, isolating oxygen and absorbing heat. Through the action of the inhibitor, it prevents the thermal runaway single cell from igniting the adjacent battery combination, effectively blocking the spread speed of the thermal runaway fault.

[0048] The heat diffusion suppression plate 8 is installed directly above the battery array composed of the single battery 1, the phase change sheet 2, and the elastic foam 3. When any single battery 1 in the battery pack undergoes thermal runaway, its volume expands. The single battery 1 first bulges, and the elastic foam 3 at other positions is squeezed and compressed, causing the adjacent single batteries 1 to move away from the thermally runaway single battery 1. The heat diffusion suppression plate 8 at the top is heated and cracked to release the flame retardant, directly cooling the thermally runaway single battery 1 and generating gas to isolate the oxygen in the air, further delaying the spread of thermal runaway.

[0049] In a preferred embodiment, the elastic foam 3, the first heat insulation foam 6, and the second heat insulation foam 7 are open-cell foams made of melamine, with a density of 8 kg / m 3 ~50 kg / m 3 。

[0050] Specifically, the elastic foam 3, the first heat insulation foam 6, and the second heat insulation foam 7 are melamine foams, with a density of 8 kg / m 3 ~50 kg / m 3 ,and the elastic foam 3 is installed between the combination composed of two single batteries 1 and one phase change sheet 2.

[0051] In a preferred embodiment, the end plate 4 is a rigid foam, with a density of 50 kg / m 3 ~200 kg / m 3 。

[0052] Specifically, the end plate 4 is a rigid foam, preferably poly (methyl methacrylimide) (PMI) foam, with a density of 50 kg / m 3 ~200 kg / m 3 ,and the end plate 4 is installed at both ends of the array formed by the single battery 1, the phase change sheet 2, and the elastic foam 3 to protect the end single battery 1;

[0053] The present invention adopts the design of the end plate 4, which can achieve heat insulation and lightweight design, and at the same time protect the end single battery 1 from deformation. Then, melamine foam with good resilience is used, so that there is enough space when the battery expands, ensuring that the battery stack will not generate excessive deformation or excessive pressure during charge and discharge.

[0054] In a preferred embodiment, the heat diffusion suppression plate 8 is a perfluoroketone nano-microcapsule plate. The perfluoroketone nano-microcapsule plate includes a plurality of nano-scale microcapsules, each microcapsule encapsulates a flame retardant inside, and the outside of the microcapsule is a thermosensitive layer wrapping the flame retardant.

[0055] Specifically, the heat diffusion suppression plate 8 is installed directly above the battery array composed of the single cell 1, the phase change sheet 2, and the elastic foam 3. When any single cell 1 in the battery pack undergoes thermal runaway, its volume expands. The single cell 1 first bulges, and the elastic foam 3 at other positions is squeezed and compressed, causing the adjacent single cells 1 to move away from the thermally runaway single cell 1. The perfluoroketone nanomicrocapsule plate at the top is heated and ruptured, releasing the flame retardant, directly cooling the thermally runaway single cell 1, and isolating the oxygen in the air, further delaying the spread of thermal runaway.

[0056] More specifically, the perfluoroketone nanomicrocapsule plate is composed of nanoscale microcapsules. Each microcapsule encapsulates the flame retardant perfluoroketone inside, and is wrapped by a thermosensitive material outside. The thermosensitive material will melt or rupture during battery thermal runaway. When a certain single cell 1 in the battery pack undergoes thermal runaway, its temperature rises rapidly. When the temperature reaches the critical temperature of the thermosensitive material of the perfluoroketone nanomicrocapsule plate, the thermosensitive material begins to melt or rupture. After the thermosensitive material ruptures, the perfluoroketone inside the microcapsule is released and rapidly vaporizes, absorbing a large amount of heat, thereby reducing the temperature of the thermally runaway single cell 1 and its surrounding environment, and isolating the oxygen in the air, inhibiting the progress of the combustion reaction, and thus preventing the spread of fire.

[0057] In a preferred embodiment, the battery array is arranged inside the housing 5, and a breakable safety seam 9 is provided in the exact middle of the housing 5.

[0058] Specifically, the safety seam 9 is used to prevent the phenomenon of thermal runaway from spreading to the entire battery pack through the housing 5 when the battery pack undergoes thermal runaway. When the internal pressure of the battery pack reaches a certain threshold, the safety seam 9 will break, thereby releasing the internal pressure and avoiding the rupture of the housing 5 or the spread of thermal runaway.

[0059] In the present invention, the safety seam 9 and the heat-insulating foam cooperate. After the safety seam 9 breaks, the first heat-insulating foam 6 and the second heat-insulating foam 7 will displace towards the two end plates 4 respectively, and the overlapping area continues to block the spread of thermal runaway from the position of the safety seam 9, further delaying the spread speed of thermal runaway.

[0060] In a preferred embodiment, the elastic foam 3 is in a compressed state. When the single cell 1 is in a discharged state, the compression ratio of the elastic foam 3 is 40% - 50%. When the single cell 1 is in a fully charged state, the compression ratio of the elastic foam 3 is 50% - 95%.

[0061] After assembly, the single cell 1 is a fresh cell in a discharged state, and the elastic foam 3 is in a compressed state with a compression ratio of 40% - 50%, enabling the overall composite battery pack to have strong mechanical properties while keeping the single cell 1 in a compressed state all the time, improving the cycle performance of the single cell 1; when the single cell 1 is in a fully charged state and the elastic foam 3 is in a compressed state with a compression ratio of 50% - 95%, the adaptability of the total volume of charging volume expansion and irreversible expansion is achieved.

[0062] In a preferred embodiment, the density of the phase change sheet 2 is 1000 kg / m 3 ~1500 kg / m 3 , and the phase change temperature is 52°C - 60°C.

[0063] By adopting low - density melamine foam and the phase change sheet 2, the present invention minimizes the weight of the battery pack.

[0064] In a specific embodiment, the single cell 1 is a lithium - ion battery single cell with a high expansion rate, and multiple single cells 1 are arranged in an array in a specified series - parallel manner;

[0065] The phase change sheet 2 can absorb heat through solid - liquid phase change, with a density of 1000 kg / m 3 ~1500 kg / m 3 , the phase change temperature is between 52°C and 60°C, and one phase change sheet 2 is installed between every two single cells 1, forming a combination of two single cells 1 and the phase change sheet 2;

[0066] The elastic foam 3 is melamine foam with a density of 8 kg / m 3 ~50 kg / m 3 , and the elastic foam 3 is installed between the combinations composed of two single cells 1 and one phase change sheet 2; the end plate 4 is rigid foam, preferably PMI foam, with a density of 50 kg / m 3 ~200 kg / m 3 , and the end plate 4 is installed at both ends of the battery array to protect the end single cells 1;

[0067] The first thermal insulation foam 6 and the second thermal insulation foam 7 are melamine foam with a density of 8 kg / m 3 ~50 kg / m 3, the first thermal insulation foam 6 and the second thermal insulation foam 7 are installed inside the housing 5; the heat diffusion suppression plate 8 is made of a perfluoromethylcyclohexanone nano-microcapsule plate and is installed directly above the battery array. When any single battery 1 in the battery pack undergoes thermal runaway, its volume expands. The single battery 1 first bulges, and the elastic foam 3 at other positions is squeezed and compressed, causing the adjacent single batteries 1 to move away from the thermally runaway single battery 1. The perfluoromethylcyclohexanone nano-microcapsule plate at the top is heated and ruptured, directly cooling the thermally runaway single battery 1 and generating gas to isolate oxygen in the air, further delaying the spread of thermal runaway; the safety seam 9 is located in the exact middle of the housing 5.

[0068] After assembly, when the single battery 1 is a fresh battery in a discharged state, the elastic foam 3 is in a compressed state with a compression ratio of 40% - 50%; when the single battery 1 is in a fully charged state, the elastic foam 3 is in a compressed state with a compression ratio of 50% - 95%, achieving adaptability to the overall volume of charging volume expansion and irreversible expansion.

[0069] The elastic foam 3, the first thermal insulation foam 6, and the second thermal insulation foam 7 are fully immersed in a solvent containing 1% - 5% inhibitor. After a period of time, they are taken out and dried.

[0070] When the single battery 1 undergoes thermal runaway, the volume of the single battery 1 expands rapidly, and the adjacent single batteries 1 are pushed towards the two end plates 4. When the thrust received by the housing 5 ≥ 200 kg, it breaks at the safety seam 9. The first thermal insulation foam 6 and the second thermal insulation foam 7 displace towards the two end plates 4 respectively, and the overlapping position can still block the spread of thermal runaway from the safety seam 9 position. The length of the overlapping area accounts for 50% - 100% of the length of the battery pack.

[0071] The present invention significantly extends the diffusion time of battery thermal runaway and improves the safety of vehicle occupants by means of the phase change sheet 2, perfluoromethylcyclohexanone nano-microcapsules, and the method of coating the micro-surface of melamine foam with a flame retardant.

[0072] The above are only the preferred embodiments of the present invention, and do not limit the implementation manners and protection scope of the present invention accordingly. For those skilled in the art, it should be realized that all equivalent substitutions and obvious changes made by using the description and illustrations of the present invention should be included in the protection scope of the present invention.

Claims

1. A composite battery pack with heat diffusion suppression, characterized in that, It includes a battery array, a housing (5), a first thermal insulation foam (6), a second thermal insulation foam (7), and a safety seam (9). The battery array includes, a plurality of single cells (1) arranged in an array in a preset series-parallel manner; phase change sheets (2), with one phase change sheet (2) provided between every two single cells (1) to form a combination; elastic foam (3) provided between adjacent combinations; a heat diffusion suppression plate (8) provided directly above the battery array, which is configured to be heated and ruptured to release a flame retardant when a single cell (1) undergoes thermal runaway; the first thermal insulation foam (6) and the second thermal insulation foam (7) are wrapped around the outside of the battery array; the middle part of the first thermal insulation foam (6) is attached to the first side surface of the battery array, and the two ends extending from the middle part of the first thermal insulation foam (6) respectively cover at least a part of the upper end surface and the lower end surface of the battery array; the middle part of the second thermal insulation foam (7) is attached to the second side surface of the battery array, and the two ends extending from the middle part of the second thermal insulation foam (7) respectively cover at least a part of the upper end surface and the lower end surface of the battery array, and are staggeredly stacked above or below the first thermal insulation foam (6).

2. The heat diffusion suppression type composite battery pack according to claim 1, wherein The sponge matrix micro-surfaces of the elastic foam (3), the first thermal insulation foam (6), and the second thermal insulation foam (7) are provided with a flame retardant coating layer.

3. The heat diffusion suppression type composite battery pack according to claim 1, wherein The elastic foam (3), the first thermal insulation foam (6) and the second thermal insulation foam (7) are open-cell foams made of melamine, with a density of 8 kg / m 3 ~50 kg / m 3 .

4. The heat diffusion suppression type composite battery pack according to claim 1, wherein The battery array further includes end plates (4) located at both ends of the battery array for protecting the single cells (1) at the ends.

5. The heat diffusion suppression type composite battery pack according to claim 4, characterized in that The end plate (4) is made of rigid foam with a density of 50 kg / m 3 ~200 kg / m 3 .

6. The heat diffusion suppression type composite battery pack according to claim 1, characterized in that, The heat diffusion suppression plate (8) is a perfluoroketone nano-microcapsule plate. The perfluoroketone nano-microcapsule plate includes a plurality of nano-scale microcapsules. Each microcapsule encapsulates the flame retardant, and the outside of the microcapsule is a thermal-sensitive layer that wraps the flame retardant.

7. The heat diffusion suppression type composite battery pack according to claim 1, characterized in that, The battery array is disposed in the housing (5), and the safety seam (9) that can be disconnected is provided in the exact middle of the housing (5).

8. The heat diffusion suppression type composite battery pack according to claim 1, wherein, The elastic foam (3) is in a compressed state. When the single cell (1) is in a discharged state, the compression rate of the elastic foam (3) is 40% - 50%. When the single cell (1) is in a fully charged state, the compression rate of the elastic foam (3) is 50% - 95%.

9. The heat diffusion suppression type composite battery pack according to claim 1, wherein The density of the phase change sheet (2) is 1000 kg / m 3 ~1500 kg / m 3 , and the phase change temperature is 52 °C to 60 °C.

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