Battery assembly and electric device

Abstract

An electric device, comprising a battery assembly. The battery assembly is provided with a heat-absorbing member between any two adjacent battery units, wherein each battery unit includes N cells arranged in sequence, N≥1, the heat-absorbing member includes a heat-absorbing main material, and the mass of the heat-absorbing main material satisfies a relational expression defined in the present application, thereby ensuring that the heat-absorbing member can effectively suppress thermal diffusion from a cell undergoing thermal runaway, without significantly reducing the space utilization rate of the battery assembly.

Description

Battery components and electrical equipment

[0001] This application claims priority to Chinese Patent Application No. 202411219597.9, filed on August 30, 2024, entitled “Battery Components and Electrical Equipment”, the entire contents of which are incorporated herein by reference. Technical Field

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

[0003] Sustained overcharging, or impacts / punctures, can easily trigger internal short circuits within the battery cell, leading to thermal runaway and affecting neighboring cells. To suppress the thermal propagation during thermal runaway, aerogels are typically used to inhibit heat diffusion between cells. However, aerogels can only delay heat transfer and cannot effectively absorb the large amounts of heat released from within the cell, thus failing to effectively block the thermal propagation of cells in thermal runaway. Therefore, it is necessary to develop a technical solution that can effectively block the thermal propagation of cells in thermal runaway. Summary of the Invention

[0004] The technical problem to be solved by this application is to provide a battery component and electrical device to solve the problem that the prior art cannot effectively absorb the large amount of heat released by the battery cell under thermal runaway conditions.

[0005] To solve the above problems, this application provides the following technical solution:

[0006] This application proposes a battery assembly comprising a plurality of battery cells arranged sequentially, with a heat-absorbing element disposed between any two adjacent battery cells; each battery cell contains N cells arranged sequentially, where N≥1; the heat-absorbing element comprises a heat-absorbing main material, which in turn comprises a heat-absorbing material, and the heat-absorbing main material satisfies the following:

[0007] (0.2*Q 电量 *m cell_res / m cell -m cell’ *c cell’ *(T vap -T env )) / (ΔH vap +c*(T vap -T env ))≤m≤

[0008] (0.56*Q 电量 *m cell_res / m cell -m cell’ *c cell’ *(T vap -Tenv )) / (ΔH vap +c*(T vap -T env ));

[0009] Among them, Q 电量 The equivalent total fully charged energy of N cells in a battery cell adjacent to the heat absorber is expressed in kJ.

[0010] m cell and m cell_res These are the average mass of N cells in a battery cell adjacent to the heat absorber before thermal runaway and the average mass after thermal runaway, respectively, in kg;

[0011] m cell’ The average mass of N cells in another battery cell adjacent to the heat absorber, in kg; c cell’ The specific heat capacity of the cell in another battery cell adjacent to the heat absorber, in kJ / (kg·K);

[0012] m is the mass of the heat-absorbing main material, in kg; T vap T represents the phase transition temperature of the heat-absorbing material, expressed in °C. env ΔH represents the ambient temperature of the heat-absorbing material, expressed in °C. vap c represents the latent heat of phase change of the heat-absorbing material, in kJ / kg; c represents the specific heat capacity of the heat-absorbing material, in kJ / (kg·K).

[0013] This application also proposes an electrical device that includes the aforementioned battery assembly.

[0014] Compared with the prior art, the embodiments of this application have the following advantages:

[0015] In this embodiment, a heat-absorbing element is provided between adjacent battery cells in the battery assembly. The heat-absorbing element includes a heat-absorbing main material, which in turn includes a heat-absorbing material. The mass of the heat-absorbing main material is designed based on the heat absorption characteristics of the heat-absorbing material, the heat transferred from a thermally runaway cell in a battery cell adjacent to the heat-absorbing element to the side of the heat-absorbing element through the battery cell, and the heat absorption of a cell in another battery cell adjacent to the heat-absorbing element. By controlling the mass of the heat-absorbing main material in the heat-absorbing element to satisfy the above relationship, it can be effectively ensured that the heat generated by the thermally runaway cell in the battery cell can be largely absorbed by the heat-absorbing element, thereby effectively reducing the heat diffusion to adjacent battery cells and avoiding thermal runaway in adjacent battery cells. This improves the overall safety of the battery assembly and ensures a high effective space utilization rate for the battery assembly, avoiding the heat-absorbing element occupying too large a volume.

[0016] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit this application. Attached Figure Description

[0017] Figure 1 is a schematic diagram of the structure of a battery assembly provided in an embodiment of this application;

[0018] Figure 2 is a cross-sectional schematic diagram of the heat absorber;

[0019] Figure 3 is a schematic diagram of the combination of the battery cell and the heat-absorbing component in the battery assembly provided in the embodiment of this application;

[0020] Figure 4 is a schematic diagram of the structure of a battery assembly provided in another embodiment of this application.

[0021] Explanation of reference numerals in the attached drawings: 100: Battery assembly; 11: Battery cell; 111: Battery cell; 111a: Large surface; 111b: Small surface; 12: Heat-absorbing component; 121: Heat-absorbing material; 122: Substrate; 123: Encapsulation component. Detailed Implementation

[0022] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0023] The applicant of this application discovered that in order to suppress the thermal propagation of the battery cell during the thermal runaway process, aerogel can usually be used to suppress the thermal diffusion between the battery cells. However, aerogel can only delay the transfer of heat and cannot effectively absorb the large amount of heat released inside the battery cell under the operating conditions of battery cell abuse.

[0024] To address the aforementioned problems, this application provides a battery assembly 100, which, as shown in Figures 1 and 4, includes a plurality of sequentially arranged battery cells 11, with a heat-absorbing element 12 positioned between any two adjacent battery cells 11. Each battery cell 11 contains N sequentially arranged cells 111, where N ≥ 1, as shown in Figure 2. The heat-absorbing element 12 includes a heat-absorbing main material, which comprises a heat-absorbing material 121. The heat-absorbing main material satisfies the following conditions:

[0025] (0.2*Q 电量 *m cell_res / m cell -m cell’ *c cell’ *(T vap -T env )) / (ΔH vap +c*(T vap -T env ))≤m≤

[0026] (0.56*Q 电量 *m cell_res / mcell -m cell’ *c cell’ *(T vap -T env )) / (ΔH vap +c*(T vap -T env ));

[0027] Among them, Q 电量 The equivalent total fully charged energy of N cells 111 in a battery cell 11 adjacent to the heat absorber 12 is expressed in kJ; m cell and m cell_res , respectively, represent the average mass of N cells 111 in a battery cell 11 adjacent to the heat absorber 12 before and after thermal runaway, in kg; m represents the mass of the heat-absorbing main material, in kg; m cell’ The average mass of N cells 111 in another battery cell 11 adjacent to the heat absorber 12, in kg; c cell’ T represents the specific heat capacity of cell 111 in another battery cell 11 adjacent to the heat absorber 12, expressed in kJ / (kg·K); vap T represents the phase transition temperature of the heat-absorbing material 121, in °C. env ΔH represents the ambient temperature of the heat-absorbing material, expressed in °C. vap ν is the latent heat of phase change of the heat-absorbing material 121, in kJ / kg; c is the specific heat capacity of the heat-absorbing material 121, in kJ / (kg·K).

[0028] In this application, thermal runaway refers to a series of exothermic chemical reactions inside the battery cell caused by overheating, short circuit, overcharging, or mechanical damage. These reactions rapidly generate a large amount of heat, causing the battery temperature to rise sharply. The mass "before thermal runaway" can be understood as the mass of the battery cell under normal operating conditions and without thermal runaway. The sign of thermal runaway is that the voltage of the battery cell drops to 0 and the explosion-proof valve opens. The mass "after thermal runaway" can be understood as the mass of the battery cell after experiencing thermal runaway, with the temperature rapidly rising from room temperature and then decreasing until it drops back to room temperature.

[0029] In the above relationship, Q 电量 The equivalent total fully charged energy of N cells 111 in a battery cell 11 adjacent to the heat absorber 12 is the key source of heat generated when the N cells 111 in the battery cell 11 experience thermal runaway, and m cell_res / m cell This reflects the degree of thermal runaway in cell 111; the inventors discovered through numerous experiments that 0.2*Q 电量 *m cell_res / m cell and 0.56*Q 电量 *m cell_res / m cell This can reflect the minimum and maximum values ​​of heat transferred from the thermally runaway cell through its side facing the heat absorber 12 (that is, the side of the cell adjacent to the heat absorber in the battery cell facing the heat absorber, denoted as the first surface). Wherein, Q... 电量 =N*U*q*3.6, where U and q are the rated voltage and rated capacity of the cell in a battery unit adjacent to the heat absorber, respectively, in V and Ah.

[0030] Considering that the heat transferred from the thermal runaway cell to its side facing the heat absorber 12 will also be absorbed by the cell 111 in another battery cell 11 adjacent to the heat absorber 12, the inventors discovered through numerous experiments that by m cell’ *c cell’ *(T vap -T env This can reflect the heat absorbed by cell 111 in another battery cell 11.

[0031] Therefore, (0.2*Q) 电量 *m cell_res / m cell -m cell’ *c cell’ *(T vap -T env )) / (ΔH vap +c*(T vap -T env This reflects the minimum mass of the required heat-absorbing material in kg, i.e., the lower limit of the mass of the heat-absorbing material in kg, (0.56*Q) 电量 *m cell_res / m cell -m cell’ *c cell’ *(T vap -T env )) / (ΔH vap +c*(T vap -T env This can reflect the maximum mass of the required heat-absorbing main material in kg, that is, the upper limit of the mass of the heat-absorbing main material in kg.

[0032] Through extensive experimental research, the inventors of this application discovered that when the mass of the heat-absorbing main material (in kg) satisfies the above-mentioned relationship, precise design of the heat-absorbing component can be achieved. When the mass of the heat-absorbing main material is greater than or equal to the lower limit of the above-mentioned mass, it can effectively ensure that the heat generated by the cell that experiences thermal runaway can be largely absorbed by the heat-absorbing component, thereby effectively reducing the heat diffusion to adjacent battery cells and avoiding thermal runaway of those adjacent battery cells, thus improving the safety of the battery assembly. When the mass of the heat-absorbing main material is less than or equal to the upper limit of the above-mentioned mass, the volume ratio of the heat-absorbing component in the battery assembly can be smaller, thereby allowing a larger number of battery cells to be contained in a battery assembly of a certain volume, resulting in higher space utilization and larger output power of the battery assembly.

[0033] In this embodiment, when the heat-absorbing main material satisfies the aforementioned relationship as defined in this application, the ratio of the thickness of the heat-absorbing element to the sum of the thicknesses of the battery cell (this ratio is denoted as the thickness percentage of the heat-absorbing element) does not exceed 25%. In this way, the battery assembly can contain a larger number of cells, resulting in higher space utilization and greater output power.

[0034] In the above formulas, the parameters are calculated without units. For example, "c is the specific heat capacity of the heat-absorbing material, in kJ / (kg·K)" means that c is the value of the heat-absorbing material in kJ / (kg·K).

[0035] The above parameter ΔH vap T vap This can be obtained through differential scanning calorimetry (DSC). Specifically, a predetermined mass m1 of heat-absorbing material can be removed from the heat-absorbing element, and the temperature T at which this predetermined mass of heat-absorbing material undergoes a phase transition during the temperature rise can be recorded. vap Test its performance during phase transition, at times greater than T vap The total heat H released below a predetermined temperature (e.g., 300℃) can be used to calculate the heat released per unit mass of the heat-absorbing material during a phase change, based on H / m1. This gives the latent heat of phase change ΔH of the heat-absorbing material. vap In addition, the DSC testing protocol has proprietary testing equipment, such as differential scanning calorimetry (DSC).

[0036] The above parameter c cell’ This can be obtained through testing, and specific testing methods include:

[0037] The battery cell (which is functioning normally and has not experienced thermal runaway) is weighed to obtain its mass as m1. A heating element (smaller than the battery cell, which can be clamped) is fixed between the large surfaces of two battery cells and placed in an insulated environment at a temperature of 25–35℃ (±3℃). The heating power is adjusted to raise the temperature of the battery cell from 25℃ (±3℃) to 35℃ (±3℃) with a constant heating power P, while keeping the heating rate constant within the range of 0.2–0.3℃ / min. Thermocouples are placed on the large surfaces of the battery cells to obtain the actual temperature rise rate dT / dt of the battery cell during the heating process, based on ΔQ=c cell’ ×m1×ΔT=P×Δt, and ΔT / Δt=dT / dt, then through c cell’ =P / [m1×(dT / dt)] gives c cell’ The specific value.

[0038] It should be noted that the ambient temperature of the heat-absorbing material is basically the same as that of the battery module (or battery cell). Therefore, for ease of measurement, the above T... env This can be done by measuring the ambient temperature of the battery pack (or battery cell).

[0039] The aforementioned relationship satisfied by the heat-absorbing element is universal and can be applied to the fabrication of heat-absorbing elements on various battery cells of different systems, models, and shapes. For example, the battery cell may include, but is not limited to, lithium-ion, sodium-ion, potassium-ion, and zinc-ion cells. The shape of the battery cell can be square, hexagonal prism, or irregular.

[0040] In one specific embodiment, the positive electrode material of the aforementioned battery cell 111 comprises a layered oxide, and the heat-absorbing main material satisfies:

[0041] (0.25*Q 电量 *m cell_res / m cell -m cell’ *c cell’ *(T vap -T env )) / (ΔH vap +c*(T vap -T env ))≤m≤

[0042] (0.56*Q 电量 *m cell_res / m cell -m cell’ *c cell’ *(T vap -T env )) / (ΔH vap +c*(T vap -T env)).

[0043] In this embodiment, when the positive electrode material of the battery cell 111 includes layered oxide, for example, the battery cell 111 is a ternary lithium battery cell, the inventors found that the above relationship can accurately estimate the heat value transferred by the thermally runaway battery cell 111 in the battery cell 11 to the side of the heat absorber 12 through the battery cell 111, thereby limiting the required amount range of the heat absorber material.

[0044] In this embodiment, when the amount of heat-absorbing main material satisfies the above-mentioned relationship, it can effectively absorb the large amount of heat released by the ternary lithium battery cell under thermal runaway conditions, while ensuring the space utilization rate of the battery module 100.

[0045] In another specific embodiment, the positive electrode material of cell 111 includes lithium iron phosphate, and the heat-absorbing main material satisfies:

[0046] (0.2*Q 电量 *m cell_res / m cell -m cell’ *c cell’ *(T vap -T env )) / (ΔH vap +c*(T vap -T env ))≤m≤

[0047] (0.45*Q 电量 *m cell_res / m cell -m cell’ *c cell’ *(T vap -T env )) / (ΔH vap +c*(T vap -T env )).

[0048] In this embodiment, when the positive electrode material of the battery cell 111 includes lithium iron phosphate, for example, the battery cell 111 is a lithium iron phosphate battery cell, the inventors found that the above relationship can accurately estimate the heat value transferred by the thermally runaway battery cell 111 in the battery cell 11 to the side of the heat absorber 12 through the battery cell 111, thereby limiting the required amount range of the heat absorber material.

[0049] In this embodiment, when the amount of heat-absorbing main material satisfies the above-mentioned relationship, it can effectively absorb the large amount of heat released by the lithium iron phosphate cell under thermal runaway conditions, while ensuring the space utilization rate of the battery module 100.

[0050] In the embodiments of this application, the phase change temperature T of the heat-absorbing material described above is... vapThe phase transition temperature is between 80℃ and 180℃. Heat-absorbing materials with a phase transition temperature within this range can effectively absorb the heat from adjacent cells before they become uncontrolled, thereby effectively preventing heat diffusion and propagation. Optionally, the phase transition temperature T of the aforementioned heat-absorbing material... vap It can be a range of one or any two of 80℃, 90℃, 100℃, 120℃, 150℃, and 180℃.

[0051] In the embodiments of this application, the latent heat of phase change ΔH of the heat-absorbing material described above is... vap ≥500kJ / kg. High heat-absorbing materials with a phase change latent heat of 500kJ / kg have better heat absorption capacity, better suppress the heat generation and diffusion of thermal runaway cells, and can avoid excessive thickness of heat-absorbing materials, which would occupy a large space in the battery module and affect the volume utilization rate of the battery module.

[0052] In some embodiments of this application, the latent heat of phase change ΔH of the heat-absorbing material is... vap Within the range of 500 kJ / kg to 2200 kJ / kg, this heat-absorbing material exhibits high heat absorption capacity and is readily available. Specifically, the ΔH... vap The values ​​can be 500kJ / kg, 600kJ / kg, 800kJ / kg, 900kJ / kg, 1000kJ / kg, 1200kJ / kg, 1500kJ / kg, 1600kJ / kg, 1800kJ / kg, 2000kJ / kg, 2100kJ / kg, etc.

[0053] In this embodiment, the heat-absorbing material includes at least one of hydrogel and hydrated salt, which can efficiently absorb heat from the thermally runaway battery cell. Taking hydrogel as an example, a polymer material with a network structure can be used as the matrix 122 of the hydrogel, and water can be used as the liquid phase change medium.

[0054] In some embodiments of this application, the side of a battery cell 111 adjacent to the heat absorber 12 facing the heat absorber 12 is referred to as the first surface. The ratio of the surface area of ​​the heat absorber 12 in contact with the first surface (e.g., denoted as S1) to the area of ​​the first surface (e.g., denoted as S2) is greater than or equal to 0.8 and less than or equal to 1, that is, S1 / S2 is in the range of 0.8 to 1. This not only ensures that the heat absorber 12 can completely adhere to the surface of the battery cell, but also makes full use of the first surface of the battery cell 111 for contact heat absorption. Preferably, the area of ​​the surface of the heat absorber 12 in contact with the first surface is equal to the area of ​​the first surface, so that the heat absorber 12 can fully absorb the heat transferred from the first surface of the battery cell adjacent to the heat absorber 12.

[0055] In some embodiments of this application, the side of a battery cell 111 adjacent to the heat absorber 12 facing the heat absorber 12 is referred to as the first surface. The distance between the geometric center of the surface of the heat absorber 12 in contact with the first surface and the geometric center of the first surface is less than or equal to 1 mm and greater than or equal to 0. That is, by setting the heat absorber 12 close to the geometric center of the first surface of the battery cell 111, the heat absorber 12 can be applied to the battery cell 111 more effectively.

[0056] In some embodiments of this application, the battery cell 111 is a square battery with a square casing. The first surface can specifically be the large surface of the square casing, that is, the side with the largest area in the square casing of the battery cell 111. Referring to Figure 3, Figure 3 is a structural schematic diagram of a battery cell 111 with a heat-absorbing element 12 disposed on its surface according to an embodiment of this application.

[0057] The battery cell 111 in Figure 3 is a square battery cell, which includes a square shell with a heat-absorbing element disposed on the large surface of the shell. In Figure 3, a' and b' are the length and height of the first surface in the shell where the heat-absorbing element 12 is disposed, respectively, and c' is the dimension of the shell in the direction perpendicular to the side surface where the heat-absorbing element is disposed; c' can be called the width of the shell. The plane formed by the length a' and height b' of the shell is the large surface 111a of the shell, and the plane formed by the height b' and width c' of the shell is the small surface 111b of the shell. Generally, a' ≥ b' > c'.

[0058] In this application, the heat-absorbing element 12 can be sheet-like, with a thickness less than its lateral dimension, and is attached to the side of the battery cell 11. In this case, the heat-absorbing element 12 can also be referred to as a "heat-absorbing sheet". The thickness direction of the heat-absorbing element 12 is perpendicular to the first surface of the battery cell 111. The smaller thickness of the sheet-like heat-absorbing element facilitates greater space utilization in the battery assembly 100 containing multiple battery cells 111. The cross-sectional shape of the heat-absorbing element 12 can be a regular rectangle, pentagon, hexagon, or other irregular shape. In some embodiments, the cross-sectional shape of the heat-absorbing element 12 is rectangular (as shown in Figure 3), consistent with the shape of the housing. In Figure 3, the thickness c of the heat-absorbing element 12 is much smaller than its length a and its width b. The thickness c of the heat-absorbing element 12 is also much smaller than the width c' of the housing. Furthermore, the length a of the heat-absorbing element 12 can be less than, equal to, or greater than the length a' of the housing, and the width b of the heat-absorbing element 12 can be less than, equal to, or greater than the height b' of the housing. Figure 3 provides an example using the case of "less than".

[0059] In some embodiments of this application, the heat-absorbing main material includes a substrate 122 and a heat-absorbing material 121. The substrate 122 has multiple pores, and the heat-absorbing material 121 fills the pores. The substrate 122 is used to provide support for the heat-absorbing material 121 and to support the heat-absorbing material 121. Optionally, the material of the substrate 122 is glass fiber.

[0060] In some embodiments of this application, as shown in FIG2, the heat-absorbing element 12 further includes an encapsulation element 123, in which the heat-absorbing main material is encapsulated. The presence of the encapsulation element 123 enhances the protection of the heat-absorbing main material, preventing leakage or detachment of the effective components within the heat-absorbing main material.

[0061] In one specific embodiment, the material of the encapsulation component 123 is selected from one or more of polypropylene (PP), polyethylene terephthalate (PET), polyimide (PI), thermoplastic polyurethanes (TPU), and aluminum-plastic film. These materials have a certain degree of flexibility, allowing the encapsulation component 123 to adhere tightly to the surface of the substrate 122 and the heat-absorbing material, thus providing good protection.

[0062] In some embodiments, the encapsulation 123 may be rectangular, and its two sides or all four sides may be heat-sealed. Furthermore, the thickness of the encapsulation 123 can be designed according to actual needs. In one embodiment, the encapsulation 123 may be very lightweight, with the mass of the heat-absorbing main material being similar to the mass of the heat-absorbing component 12. The mass of the heat-absorbing main material can be considered as the mass of the heat-absorbing component 12. In another embodiment, the mass of the encapsulation 12 may be close to or exceed the mass of the heat-absorbing main material; in this case, only the mass of the heat-absorbing main material is calculated. Further, when the mass of the encapsulation 123 is less than 10% of the mass of the heat-absorbing main material, for ease of measurement, the mass of the heat-absorbing component 12 can be considered as the mass of the heat-absorbing main material.

[0063] In some other embodiments of this application, the heat-absorbing main material does not include a matrix; the heat-absorbing main material may be only the aforementioned heat-absorbing material. The aforementioned heat-absorbing material can be directly encapsulated in a package. Whether the heat-absorbing main material includes both a matrix and the heat-absorbing material, or only the heat-absorbing material, the heat-absorbing main material is located within the package to achieve a seal, preventing phase change in the heat-absorbing material and thus reducing its mass, thereby ensuring the heat absorption effect of the heat-absorbing material.

[0064] In this embodiment, multiple battery cells 11 are arranged along a first direction, and N battery cells 111 in each battery cell 11 are arranged along the first direction, with each battery cell 11 containing the same number of battery cells 111. For the battery cells 111 being square cells, the first direction is parallel to the thickness direction of the heat-absorbing element 12 or the thickness direction of the battery cell 111. Of course, it is understood that in other embodiments, the arrangement directions of the multiple battery cells 11 and the N battery cells 111 may be different. For example, the multiple battery cells 11 may be arranged along the length or width direction of the battery cell 111, and the N battery cells 111 may be arranged along the thickness direction of the battery cell 111.

[0065] In some embodiments of this application, if the battery cell 111 is designated as A and the heat absorber 12 as B, and each battery cell 11 includes N=1 battery cells 111, and any two adjacent battery cells 11 are separated by the heat absorber 12, then along the first direction, the arrangement of the battery cells 111 and the heat absorber 12 can be ABAB…A (as shown in Figure 1), or ABAB…AB, etc. In this case, any two adjacent battery cells 111 in the battery assembly 100 are separated by the heat absorber 12. The heat absorber 12 is disposed between the large surfaces of any two adjacent battery cells 111. That is, the battery cells 111 and the heat absorber 12 are arranged alternately along the first direction (the direction indicated by the arrow in Figure 1). The placement of the heat absorber 12 between any two adjacent battery cells 111 ensures good safety performance of any battery assembly 100.

[0066] Similarly, in other embodiments of this application, if the cell 111 is designated as A and the heat absorber 12 as B, and if each battery cell 11 includes N=2 cells 111, and any two adjacent battery cells 11 are separated by the heat absorber 12, then along the first direction described above, the arrangement of the cells 111 and the heat absorber 12 can be AAB-AAB…AA (as shown in Figure 4), etc. In this case, among the multiple cells 111 of the battery assembly 100, some adjacent cells 111 are provided with a heat absorber 12, while other adjacent cells 111 are not provided with a heat absorber 12. As shown in Figure 4 from left to right (indicated by the arrows in Figure 4), no heat absorber is provided between the 1st and 2nd cells, between the 3rd and 4th cells, and between the 5th and 6th cells.

[0067] It should be noted that the number N of cells 111 included in each battery cell 11 can be equal or unequal. Figures 1 and 4 above both use the example of equal N. An example of "unequal N" is as follows: In the battery assembly 100, the arrangement of cells 111 and heat absorber 12 can be AB-AAB-AAAB-AB, etc. When the number of cells 111 in the battery cells 11 on both sides of the heat absorber 12 is different, the battery cell 11 with more cells 111 is the one adjacent to the heat absorber 12, and the battery cell 11 with fewer cells 111 is the other battery cell 11 adjacent to the heat absorber 12.

[0068] This application also proposes an electrical device that includes the aforementioned battery assembly. This electrical device can be used for energy storage or power supply, and can specifically be a vehicle, ship, energy storage system, etc.

[0069] The above-described electrical equipment embodiments include the aforementioned battery components and achieve the same technical effects. To avoid repetition, they will not be described again here. For relevant details, please refer to the description of the battery component embodiments.

[0070] To make the objectives, technical solutions, and beneficial effects of this application clearer, the application is further described below with reference to embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of this application.

[0071] The present application will be described in detail below through embodiments.

[0072] Example 1

[0073] (1) Select a ternary 811 battery cell with dimensions of 148*97*28mm (i.e., length of 148mm, height of 97mm, and width of 28mm), rated voltage U of 3.68V, rated capacity of 58Ah, and battery cell mass of 0.89kg. The specific heat capacity of the battery cell was measured to be 1.1kJ / (kg·K) in the aforementioned manner.

[0074] (2) The preparation method of the heat-absorbing element includes: selecting a gel polymer material, mixing it with water, and coating it onto a PET substrate. After curing, a hydrogel with a specific heat capacity c of 4 kJ / (kg·K) is formed. The hydrogel is peeled off from the PET substrate and cut into corresponding sizes to obtain a hydrogel with a mass of m kg (i.e., the heat-absorbing main material). The heat-absorbing main material is then heat-sealed around its perimeter using an aluminum-plastic film (0.085 mm thick) to obtain a sheet-like heat-absorbing element (which can be called a "heat-absorbing sheet"). The latent heat of phase change ΔH of the heat-absorbing material is tested using the DSC method. vap It is 1400 kJ / kg, and the phase transition temperature T vap It is 105℃;

[0075] (3) Take 5 cells of the above specifications, arrange them sequentially along their thickness, and place heat-absorbing elements between the large faces of any two adjacent cells to obtain a battery assembly. In this battery assembly, the arrangement of the cells (denoted as A) and heat-absorbing elements (denoted as B) is ABABABABA, or (AB)4A, then N=1. Measure the ambient temperature of the battery assembly, which is T. env .

[0076] (4) A needle penetration test was conducted at room temperature and with the battery cells at 100% SOC. The test procedure included: after fully charging each battery cell, using a 3mm diameter steel needle at a speed of 0.5mm / s, piercing the middle position of the battery cell in the middle battery unit (i.e., the 3rd cell in a row of 5 cells) until thermal runaway occurred, and then stopping. The test was continued until the collected temperature was less than 100℃. After the test, it was recorded whether adjacent cells had thermal runaway (the thermal runaway standard is that the voltage drops to 0 and the explosion-proof valve opens), that is, whether thermal diffusion occurred, and the residual mass m of the thermal runaway cell was weighed. cell_res Among them, according to Q 电量 =N*U*q*3.6 Calculate the equivalent fully charged energy of the thermal runaway cell, m cell The mass of the cell before thermal runaway is 0.89 kg. Based on the aforementioned relationship provided in this application, the upper and lower limits of the endothermic main material mass (i.e., m) are calculated. max and m min );

[0077] In addition, the ratio of the thickness of the heat-absorbing element to the sum of the thicknesses of the battery cells in the battery assembly is measured, where the thickness of the battery cell is also the width of the battery cell.

[0078] Battery modules for other embodiments and comparative examples were prepared according to the method described in Example 1, and their main features are listed in Tables 1 to 3.

[0079] In Examples 13-14, the latent heat of phase change of the heat-absorbing material differs from that in other examples and can be achieved by adjusting the water content in the heat-absorbing material of Example 1.

[0080] In the battery packs of Examples 10-11 and Comparative Examples 6-7, the arrangement of the battery cells (denoted as A) and the heat absorbers (denoted as B) is AABAABAABAABAABAA, or (AAB)4AA. That is, such a battery pack includes 5 battery cells, and each battery cell includes 2 square battery cells.

[0081] The difference in the nail penetration test lies in the fact that it involves puncturing two cells in the middle battery unit. cell Let m be the average mass of the two cells before thermal runaway.cell_res This represents the average mass of the two cells after thermal runaway.

[0082] The parameters and test results of each embodiment and comparative example are shown in Tables 1 to 3.

[0083] Table 1

[0084] Table 2

[0085] Table 3

[0086] Based on the experimental data in Tables 1 to 3 above, it can be seen that in the battery assembly of this application embodiment, when the mass of the heat-absorbing sheet disposed between adjacent battery cells meets the relationship required by this application, the heat-absorbing sheet can effectively suppress the thermal runaway cell from spreading heat to adjacent cells, and the ratio of the heat-absorbing sheet to the sum of the thickness of the battery cell including the cells is low, less than 25%, thereby making the total thickness of all heat-absorbing sheets in the overall battery assembly low and the effective space utilization rate of the battery assembly high.

[0087] The comparative examples show that when the amount of heat-absorbing material is relatively small, it cannot suppress heat diffusion. For example, when the actual amount of material used in Comparative Example 1 is reduced compared to the actual amount used in Example 1, the diffusion result in Comparative Example 1 is heat diffusion between the battery cells. Furthermore, based on Example 1 and Comparative Example 2, Example 4 and Comparative Example 3, Example 7 and Comparative Example 5, and Example 10 and Comparative Example 7, it can be seen that when too much material is used, although heat diffusion can be suppressed, the volume ratio of the material is relatively large, which will affect the volume utilization rate of the battery cells.

[0088] Although preferred embodiments of the present application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of the embodiments of the present application.

[0089] The battery assembly and electrical device provided in this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A battery assembly (100), characterized in that, The battery includes multiple battery cells (11) arranged in sequence, with a heat-absorbing element (12) between any two adjacent battery cells; each battery cell (11) contains N cells (111) arranged in sequence, where N ≥ 1; the heat-absorbing element (12) includes a heat-absorbing main material, which includes a heat-absorbing material (121), and the heat-absorbing main material satisfies: (0.2*Q) 电量 *m cell_res / m cell -m cell’ *c cell’ *(T vap -T env )) / (ΔH vap +c*(T vap -T env ))≤m≤ (0.56*Q 电量 *m cell_res / m cell -m cell’ *c cell’ *(T vap -T env )) / (ΔH vap +c*(T vap -T env )); Among them, Q 电量 The equivalent total fully charged energy of N cells (111) in a battery cell (11) adjacent to the heat absorber (12) is expressed in kJ. m cell and m cell_res The average mass of N cells (111) in a battery cell (11) adjacent to the heat absorber (12) before thermal runaway and the average mass after thermal runaway are respectively, in kg; m cell’ The average mass of N cells (111) in another battery cell (11) adjacent to the heat absorber (12), in kg; cell’ The specific heat capacity of the cell (111) in another battery cell (11) adjacent to the heat absorber (12), in kJ / (kg·K); m is the mass of the heat-absorbing main material, in kg; T vap T represents the phase transition temperature of the heat-absorbing material (121), in °C. env ΔH represents the ambient temperature of the heat-absorbing material (121), expressed in °C. vap c is the latent heat of phase change of the heat-absorbing material (121), in kJ / kg; c is the specific heat capacity of the heat-absorbing material (121), in kJ / (kg·K).

2. The battery assembly (100) according to claim 1, characterized in that, The positive electrode material of the battery cell (111) comprises a layered oxide, and the heat-absorbing main material satisfies: (0.25*Q) 电量 *m cell_res / m cell -m cell’ *c cell’ *(T vap -T env )) / (ΔH vap +c*(T vap -T env ))≤m≤ (0.56*Q 电量 *m cell_res / m cell -m cell’ *c cell’ *(T vap -T env )) / (ΔH vap +c*(T vap -T env )).

3. The battery assembly (100) according to claim 1, characterized in that, The positive electrode material of the battery cell (111) includes lithium iron phosphate, and the heat-absorbing main material satisfies: (0.2*Q) 电量 *m cell_res / m cell -m cell’ *c cell’ *(T vap -T env )) / (ΔH vap +c*(T vap -T env ))≤m≤ (0.45*Q 电量 *m cell_res / m cell -m cell’ *c cell’ *(T vap -T env )) / (ΔH vap +c*(T vap -T env )).

4. The battery assembly (100) according to any one of claims 1-3, characterized in that, The phase transition temperature T of the heat-absorbing material (121) vap The temperature ranges from 80℃ to 180℃.

5. The battery assembly (100) according to any one of claims 1-4, characterized in that, The latent heat of phase change ΔH of the heat-absorbing material (121) vap ≥500kJ / kg.

6. The battery assembly (100) according to any one of claims 1-5, characterized in that, The heat-absorbing material (121) includes at least one of hydrogel and hydrated salt.

7. The battery assembly (100) according to any one of claims 1-6, characterized in that, The heat-absorbing element (12) is sheet-shaped and is attached to the side of the battery cell (11).

8. The battery assembly (100) according to any one of claims 1-7, characterized in that, The heat-absorbing main material includes a matrix (122) and the heat-absorbing material (121). The matrix (122) has multiple pores, and the heat-absorbing material (121) fills the pores.

9. The battery assembly (100) according to any one of claims 1-7, characterized in that, The heat-absorbing main material is the heat-absorbing material (121).

10. The battery assembly (100) according to any one of claims 1-9, characterized in that, The heat-absorbing component (12) also includes an encapsulation component (123), in which the heat-absorbing main material is encapsulated.

11. The battery assembly (100) according to claim 10, characterized in that, The material of the encapsulation component (123) is selected from one or more of PP, PET, PI, TPU, and aluminum-plastic film.

12. The battery assembly (100) according to any one of claims 1-11, characterized in that, The side of a cell (111) adjacent to the heat absorber (12) facing the heat absorber (12) is designated as the first surface. The ratio of the surface area of ​​the heat absorber (12) in contact with the first surface to the area of ​​the first surface is greater than or equal to 0.8 and less than or equal to 1.

13. The battery assembly (100) according to any one of claims 1-12, characterized in that, The side of a cell (111) adjacent to the heat absorber (12) facing the heat absorber (12) is designated as the first surface. The distance between the geometric center of the surface of the heat absorber (12) in contact with the first surface and the geometric center of the first surface is less than or equal to 1 mm and greater than or equal to 0.

14. The battery assembly (100) according to any one of claims 1-13, characterized in that, Multiple battery cells (11) are arranged along a first direction, and N cells (111) in each battery cell (11) are arranged along the first direction, with each battery cell (11) containing the same number of cells (111).

15. The battery assembly (100) according to claim 14, characterized in that, The battery cell (111) is a square battery cell, and the first direction is parallel to the thickness direction of the battery cell (111). The heat-absorbing member (12) is disposed on the side of the battery cell (11) that is perpendicular to the thickness direction of the battery cell (111).

16. An electrical appliance, characterized in that, Includes the battery assembly (100) as described in any one of claims 1 to 15.

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