Battery assembly and device

Abstract

The present application relates to the technical field of batteries, and provides a battery assembly and a device. By controlling the size parameters of a heat absorption piece arranged on the surface of one side of a casing of a cell in the battery assembly, the mass of a heat absorption main material, the size parameters of the casing, related parameters during thermal runaway, etc. to satisfy a certain relationship, it can be guaranteed that the heat absorption piece can fully inhibit heat of a battery in thermal runaway from diffusing to an adjacent battery, and the space utilization rate of the battery assembly containing the plurality of cells is not excessively affected.

Description

Battery components and devices

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on February 6, 2024, with application number 202410174397.X and application name “Battery Assemblies and Devices”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the field of battery technology, and in particular to a battery assembly and device. Background Art

[0003] Power batteries are prone to internal short circuits and thermal runaway when continuously overcharged, or when they are impacted or punctured. To prevent thermal runaway of power cells and the spread of this to adjacent cells, the industry typically installs a flame retardant (such as aerogel) on the surface of the cell housing. However, this flame retardant is difficult to adapt to different cell types and is difficult to effectively block heat diffusion between cells. Therefore, it is necessary to develop a universal solution that can effectively block the spread of heat from cells in thermal runaway to adjacent cells. Summary of the Invention

[0004] In view of this, the present application provides a battery assembly and device to solve the problem that the flame retardant / heat absorbing medium provided on the side of the existing single battery cannot effectively prevent the heat of the thermal runaway battery from spreading to the adjacent batteries.

[0005] Specifically, the first aspect of the present application provides a battery assembly, including a single cell and a heat sink; the single cell includes a square shell, and the heat sink is provided on one side surface of the shell; the single cell is provided with an explosion-proof valve; wherein the heat sink includes a main heat-absorbing material, and the mass m0 of the main heat-absorbing material in g satisfies the following relationship: X≤m0≤400×S1×c'×ρ,

[0006] X=1000×[k×Q gen -m res ×c cell ×(T face -40)-(m cell -m res )×c cell ×(T max -40)-2m cell ×c cell ×(T p -40)] / [H p +c abs ×(T p -40)]; where k = 1.1 / (1+c' / b'+c' / a');

[0007] Among them, m cell 、m res are the mass of the single battery before and after thermal runaway, both in kg; T face 、T max They are used to set the maximum temperature of the surface of one side of the heat absorbing plate during thermal runaway and the maximum temperature of the explosion-proof valve during thermal runaway, both in ℃; c cell is the specific heat capacity of the single cell, in kJ / (kg·K); Q gen The heat generated by the single cell during thermal runaway is measured based on the accelerating calorimetry method, in kJ; T p 、H p 、c abs are the phase change temperature, latent heat of phase change and specific heat capacity of the main heat absorbing material, respectively, with units of °C, kJ / kg, and kJ / (kg·K), and ρ is the density of the heat absorbing sheet, with units of kg / m 3 ; S1 is the positive projection area of ​​the heat absorbing sheet on the surface of the side of the housing where the heat absorbing sheet is provided, in m 2 a' and b' are respectively the length and width of the side surface of the shell on which the heat absorption plate is set, both in m; c' is the dimension of the shell in a direction perpendicular to the side surface, in m.

[0008] In the battery assembly described above, a heat-absorbing sheet is disposed on one surface of a single battery cell. A relationship is established between the amount of the heat-absorbing material in the sheet, its heat-absorbing characteristics, the sheet's dimensions, and the dimensions of the battery housing. This relationship satisfies the aforementioned equation. This allows the heat generated by the single battery cell during thermal runaway to be fully absorbed by the sheet, suppressing heat diffusion and ensuring the safety of a battery system containing multiple single batteries without significantly impacting space utilization. Furthermore, the relationship satisfied by the heat-absorbing sheet is applicable to any model of single battery cell, demonstrating its universal applicability.

[0009] In a second aspect, the present application provides a device comprising the battery assembly described in the first aspect of the present application, which device is an electrical device or an energy storage system. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following briefly introduces the drawings required for use in the embodiments.

[0011] FIG1 is a schematic structural diagram of a battery assembly provided in an embodiment of the present application;

[0012] FIG2 is another schematic diagram of the structure of the battery assembly provided in an embodiment of the present application. DETAILED DESCRIPTION

[0013] The technical solutions of the embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0014] Please refer to Figure 1, which is a schematic diagram of the structure of a battery assembly provided in an embodiment of the present application. Figure 2 is another schematic diagram of the structure of a battery assembly provided in an embodiment of the present application. The battery assembly in Figure 1 includes one single cell. The battery assembly in Figure 2 includes multiple single cells. The battery assembly 100' shown in Figure 1 includes a single cell 100 and a heat-absorbing plate 20. The single cell 100 includes a shell, the shell is square, and a heat-absorbing plate 20 is provided on one side surface of the shell (the surface is 10a in Figure 1). An explosion-proof valve (not shown in Figure 1) is provided on the shell of the single cell 100.

[0015] The heat absorbing sheet 20 includes a heat absorbing main material, and the mass m0 of the heat absorbing main material in g satisfies: X≤m0≤400×S1×c'×ρ,

[0016] X=1000×[k×Q gen -m res ×c cell ×(T face -40)-(m cell -m res )×c cell ×(T max -40)-2m cell ×c cell ×(T p -40)] / [H p +c abs ×(T p -40)]; where k = 1.1 / (1+c' / b'+c' / a');

[0017] Among them, m cell 、m res are the mass of the single battery 100 before and after thermal runaway, both in kg; T face 、T max are respectively the maximum temperature of one side surface of the heat absorbing sheet 20 during the thermal runaway of the single battery and the maximum temperature of the explosion-proof valve of the single battery 100 during the thermal runaway of the single battery, both in ℃; c cell is the specific heat capacity of the single cell 100, in kJ / (kg·K); Q gen The heat generated by the single cell 100 during thermal runaway is measured based on the accelerating calorimetry method, in kJ; T p 、H p 、c abare the phase change temperature, latent heat of phase change, and specific heat capacity of the main heat-absorbing material, respectively, with units of °C, kJ / kg, and kJ / (kg·K), and ρ is the density of the heat-absorbing sheet 20, with units of kg / m 3 ; S1 is the positive projection area of ​​the heat absorbing sheet 20 on the side surface of the housing where the heat absorbing sheet is provided, in m 2 a' and b' are respectively the length and width of the surface of one side of the shell on which the heat absorbing sheet 20 is set, both in meters (m); c' is the dimension of the shell in a direction perpendicular to the surface of one side on which the heat absorbing sheet 20 is set, in meters (m).

[0018] In the present application, “the shell is square” means that the outer shape of the shell can be roughly a rectangular parallelepiped or a cube.

[0019] In this application, "thermal runaway" of a single cell 100 can be understood as the voltage of the single cell 100 dropping to zero and the explosion-proof valve opening. During testing, the method for triggering "thermal runaway" can be a needle penetration test or accelerated rate calorimetry (ARC). The specific operating methods of the needle penetration test or accelerated rate calorimetry are described below.

[0020] It should be noted that "one side surface" can refer to any surface of the square shell. The shell is provided with a heat absorbing sheet 20 on one side surface. The shell can be provided with a heat absorbing sheet on only one side surface or on multiple sides. When the shell is provided with heat absorbing sheets on multiple sides, the above parameter T face It refers to the average value of the highest temperatures of the multiple side surfaces provided with the heat absorbing sheet 20 during the thermal runaway process, and the parameter S1 refers to the heat absorbing sheet on one side of the multiple side surfaces provided with the heat absorbing sheet 20 .

[0021] In the present application, the dimensional parameters of the heat-absorbing sheet 20 disposed on one side surface of the single battery cell 100 and the quality of the heat-absorbing main material are controlled to satisfy the above-mentioned relationship. With the help of the heat-absorbing sheet 20, it is possible to ensure that the heat of any type of square single battery cell 100 experiencing thermal runaway will not spread to adjacent batteries, thereby preventing a chain reaction of thermal runaway. At the same time, the volume of the heat-absorbing sheet 20 can be made small, so that a battery system of a certain volume (such as a battery pack) can contain a larger number of such single batteries, thereby improving space utilization and increasing output power.

[0022] In addition, the above relationship is universal and can be applied to battery components including single cells of various systems (including but not limited to lithium batteries, sodium batteries, etc.).

[0023] In the present application, the heat absorbing sheet 20 may be provided on both opposing surfaces of the cell housing, or on one of the surfaces of the cell housing. The specific arrangement can be determined based on the distribution of the cells 100 within the battery pack, ensuring that a heat absorbing sheet is provided on the surface opposite the adjacent cell (this will be discussed in detail below). It is understood that when a heat absorbing sheet 20 is provided between two adjacent cells 100 in a battery assembly containing multiple cells, it is not necessary to provide two heat absorbing sheets between the two cells; they can simply share a single heat absorbing sheet.

[0024] In this application, the above k is the heat correction coefficient. k×Q gen Represents the effective heat transferred from the two surfaces perpendicular to the thickness of the heat sink 100, out of the total heat generated by the thermal runaway battery. The inventors discovered through research that during thermal diffusion, heat dispersion is closely related to the direction / surface. Based on this, after numerous experiments, they found that introducing a correction factor k can make X more accurately reflect the amount of heat that a battery needs to dissipate to the environment through the surfaces corresponding to adjacent batteries. res ×c cell ×(T face -40) represents the residual heat of the single battery 100 after thermal runaway. (m cell -m res )×c cell ×(T max -40) represents the heat removed by the explosion-proof valve during the thermal runaway process of the single battery 100. cell ×c cell ×(T p -40) represents the heat absorbed by cells adjacent to cell 100 from the cell experiencing thermal runaway and its adjacent surfaces. This represents the heat removed by cells adjacent to cell 100. The difference between the first and the next three items represents the minimum amount of heat required to be absorbed by the main heat-absorbing material of heat-absorbing sheet 20.

[0025] H p +c abs ×(T p -40) represents the heat absorption capacity of the heat absorbing main material per unit mass, and its product with m0 represents the total amount of heat that the heat absorbing main material can absorb.

[0026] 400×S1×c′×ρ=S1×c′×ρ×1000×0.4 represents the upper limit mass of the heat sink in g (multiplying by 0.4 means that the maximum thickness of the heat sink does not exceed 0.4 times the thickness of the single battery).

[0027] Therefore, by controlling the mass m0 of the main heat-absorbing material, the size of the heat-absorbing sheet, and the dimensional parameters of the battery housing to satisfy the above relationship, it is possible to effectively suppress the heat generated by a single battery in the event of thermal runaway from spreading to adjacent batteries, while at the same time preventing the volume of the heat-absorbing sheet from being excessively large.

[0028] It should be noted that in the inequality X≤m0≤400×S1×c'×ρ, the parameters are calculated without units, for example, "m cell 、m res are the mass of the single battery before and after thermal runaway, respectively, both in kg. "Meanwhile, m cell is the mass of the single cell before thermal runaway in kg, m res It is the mass of the single cell after thermal runaway in kg.

[0029] In this application, "before thermal runaway" can be understood as the quality of the single cell in normal working condition and without thermal runaway; the sign of "thermal runaway" is that the voltage of the single cell drops to 0 and the explosion-proof valve opens; "after thermal runaway" can be understood as the quality of the battery cell after experiencing thermal runaway and the temperature returns to room temperature.

[0030] The above m cell 、m res The poles are included when measuring the weight parameters of a single cell. a', b', c', S1, and ρ can be obtained by measurement. When measuring the size parameters a', b', and c' of a single cell, the size of the poles is not included. abs is the inherent parameter of the heat absorbing material selected by the heat absorbing sheet. For example, when the heat absorbing material is hydrogel, c abs The density of a substance is determined by measuring its mass in a fixed volume. Place the sample in the density meter, wait a few seconds for the sample to stabilize, and then read the value displayed on the density meter. p 、H p The temperature T at which the phase transition of the heat absorbing material occurs during the temperature rise process can be measured by using a differential scanning calorimetry (DSC) method. p , and the total heat H released during the phase change process, and then dividing H by the mass of the heat-absorbing main material to get H p .

[0031] Specific heat capacity c of the single cell 100 cellIt can be obtained through testing. The specific test method includes: weighing the single battery (which can work normally and has not experienced thermal runaway) to obtain its mass as m1; fixing a heating plate that is smaller than the single battery (can be clamped by a clamp) in the middle of the large surface of the two single batteries, and placing it in an insulating environment with a temperature of 25-35℃ (±3℃), adjusting the heating power so that the single battery is heated from 25℃ (±3℃) to 35℃ (±3℃) at a constant heating power P, and controlling the heating rate to remain unchanged, wherein the heating rate is within the range of 0.2-0.3℃ / min, arranging thermocouples on the large surface of the single battery, and obtaining the actual temperature rise rate dT / dt of the battery 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)] to obtain c cell The specific value of .

[0032] T face 、T max are respectively the maximum temperature of one side surface of the battery cell housing where the heat absorbing sheet 20 is installed during the thermal runaway process of the battery cell, and the maximum temperature of the explosion-proof valve during the thermal runaway process of the battery cell, both in °C. In this application, "thermal runaway process" can be understood as the process in which the temperature of the battery cell rises from room temperature and then drops back to room temperature during thermal runaway of the battery cell. The above T face 、T max The specific test method includes: arranging a thermocouple sampling line on the single cell. When the single cell is provided with a heat absorbing plate on only one side, the thermocouple can be placed at the center of the side of the single cell 100 where the heat absorbing plate is placed (such as the center of the large side). The highest temperature during the thermal runaway process is T face When the single cell is provided with heat absorbing sheets on both sides, thermocouples need to be set at the centers of the two sides of the single cell 100 (denoted as T1' and T1'). The average value of the highest temperature of T1' and T1' during the thermal runaway process is T face At the same time, a thermocouple (denoted as T2) needs to be arranged 2-5 mm away from the explosion-proof valve of the single battery 100. The highest temperature of T2 during the thermal runaway process is the above T max .

[0033] The above Q genIt is the heat generated by a single cell in the thermal runaway process under adiabatic conditions, measured by the accelerated calorimetry method (full name: Accelerating Rate Calorimetry, abbreviated as ARC). Specifically, the single cell is fixed and suspended in the ARC calorimetry chamber (or placed on a bracket) to be placed in an adiabatic environment with no heat exchange with the surrounding environment. When testing the ARC test, the temperature in the ARC calorimetry chamber is first raised from room temperature to 50±2°C, and left for 45 minutes to allow the battery and ambient temperature to fully balance and stabilize, and then the temperature rise rate of the battery sample is detected. If the temperature rise of the battery exceeds 0.2°C within 10 minutes (i.e. SHR>0.02°C / min; SHR is the self-heating temperature rise rate, Self-heating Rate), it is considered that a self-heating reaction has occurred inside the battery. The adiabatic environment is maintained until the battery thermal runaway occurs, and the temperature information of the entire process is recorded. For example, the temperature T at the center of the large surface of the single cell is recorded when SHR>1°C / min. i (i.e., the temperature T when SHR changes from less than or equal to 1℃ / min to greater than 1℃ / min i ) and the maximum temperature T of the above-mentioned single battery during thermal runaway max If the battery temperature rise does not exceed 0.2°C within 10 minutes (i.e., SHR ≤ 0.02°C / min), start the next step temperature rise test: continue heating to increase the temperature by 5°C (i.e., the temperature difference between two adjacent temperature steps is 5°C), and perform the above test after each step for 45 minutes until SHR>0.02°C / min, stop the "step temperature rise" mode, enter the adiabatic mode until the battery thermal runaway occurs, and record the above T i The temperature range of ARC test is 50℃~300℃. gen =m cell ×c cell ×(T max -T i ) can obtain Q gen In some embodiments of the present application, the Q gen Greater than 400kJ.

[0034] In some embodiments of the present application, the capacity of the above-mentioned single battery 100 may be in the range of 2Ah-280Ah.

[0035] In some embodiments of the present application, the heat absorbing sheet 20 includes a substrate and a heat absorbing material supported on the substrate. In some embodiments, the heat absorbing sheet 20 is also covered with a sealing film. The sealing film covers the substrate and the heat absorbing material on the substrate. The substrate can be, for example, a mesh polymer material. The sealing film can isolate water vapor from the air and can be selected from one or more materials such as PP (polypropylene), PET (polyethylene terephthalate), PI (polyimide), and TPU (thermoplastic polyurethane elastomer rubber). In some embodiments, the substrate also carries an adhesive.

[0036] In some embodiments of the present application, the phase change latent heat H of the heat absorbing main material p Above 500kJ / kg. p The larger the size, the higher its ability to absorb heat, and the better it can suppress the thermal diffusion of single cells in thermal runaway.

[0037] In some embodiments of the present application, the T p In the range of 85℃-180℃. In this way, at the beginning of thermal runaway of the single cell, the heat absorbing main material can quickly absorb heat to take away the heat and inhibit heat diffusion. Specifically, the T p The temperature may be 88°C, 90°C, 95°C, 100°C, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, etc. In some embodiments, the T p In the range of 93° C. to 130° C. For example, the heat absorbing main material may specifically include but is not limited to hydrogel, hydrated salt, or a composite thereof or a composite with other materials (such as flame retardant).

[0038] In some embodiments of the present application, the above T max Greater than 300°C. In some embodiments, T max The temperature is 700°C or higher, for example, 710, 750, 800, 850, 950, 1000°C or higher.

[0039] In some embodiments of the present application, the shell has a first side surface and a second side surface arranged opposite to each other in the thickness direction, and at least one of the first side surface and the second side surface is provided with a heat absorption plate 20; a', b', and c' are the length, width, and thickness of the shell, respectively, and the unit is m, and a'≥b'>c'.

[0040] That is, as shown in Figures 1 and 2, a heat sink 20 is provided on one or both large surfaces 10a of the cell housing. The large surface 10a is the side of the housing with the largest area. When multiple cells are assembled into a battery assembly (as shown in Figure 2), this large surface also forms the side of the cell 100 facing the adjacent cells. It can be understood that the square cell housing includes two opposing large surfaces 10a and two opposing small surfaces 10b. The two large surfaces 10a are connected by the small surfaces 10b. The two large surfaces 10a and the two small surfaces 10b form a square housing, and the cell 100 is also a square battery. The explosion-proof valve is located on the small surface 10b of the housing or at the top of the housing.

[0041] At this time, T face is the maximum temperature of the large surface 10a during the thermal runaway process, in °C; S1 is the projected area of ​​the heat absorbing plate 20 on the large surface 10a, in m 2 a', b', and c' are the length, width, and thickness of the shell, respectively, all in meters. The length a' of the shell is greater than or equal to the width b', and the width b' is greater than the thickness c'. That is, a' ≥ b' > c'. The plane formed by the length a' and the width b' of the shell is the large surface 10a of the shell, and the plane formed by the width b' and the thickness c' of the shell is the small surface 10b of the shell. In some embodiments, a' > b' > c'.

[0042] In the embodiment shown in Figure 1 , the plane defined by the length a and width b of the heat absorbing sheet 20 is parallel to the large surface 10a of the housing. In this case, the orthographic projection area S1 of the heat absorbing sheet 20 on the side of the housing on which it is disposed is equal to the product of the length a and the width b of the heat absorbing sheet 20 (i.e., S1 = a × b, where a and b are both measured in meters). The thickness c of the heat absorbing sheet 20 is generally less than its length a and width b.

[0043] 1 illustrates an example where the projected area S1 of the heat absorbing sheet 20 on the large surface 10a is smaller than the large surface 10a of the housing. It is understood that in other embodiments of the present application, S1 may also be larger than the area of ​​the housing surface where the heat absorbing sheet 20 is disposed.

[0044] In some embodiments of the present application, the ratio of the length a of the heat sink 20 to the length a' of the battery cell housing is between 0.5 and 1, i.e., 0.5a' ≤ a ≤ a'. The ratio of the width b of the heat sink 20 to the width b' of the battery cell housing is between 0.5 and 1, i.e., 0.5b' ≤ b ≤ b'. This ensures that the heat sink is a thin sheet structure with a large transverse dimension and a relatively small thickness, thereby maximizing space utilization in a battery pack or battery assembly containing multiple battery cells 100.

[0045] Furthermore, the thickness c of the heat sink 20 can be greater than or equal to 0.0002 meters. This ensures that the heat sink 20 effectively prevents heat diffusion from the battery during thermal runaway. In this embodiment, c is less than or equal to 0.5c' to ensure high space utilization in a battery pack or battery pack containing multiple such cells.

[0046] In the present application, the shell of the single cell can accommodate a pole core (not shown in the figure). The single cell 100 also has a positive pole column 101 and a negative pole column 102 exposed on the top of the shell. Among them, the pole core generally includes a plurality of positive pole sheets and a plurality of negative pole sheets, and the adjacent positive pole sheets and negative pole sheets are separated. The positive pole column 101 of the single cell 100 can be electrically connected to the positive pole sheet, and the negative pole column 102 can be electrically connected to the negative pole sheet. These two poles can serve as electrical contact points when the single cell 100 is charged and discharged. In addition, the above-mentioned single cell 100 can be a liquid battery, or an all-solid-state battery or a semi-solid-state battery.

[0047] Among them, the battery assembly 100' shown in Figure 1 can be a single battery with a heat absorption sheet on the surface. The battery assembly 200 shown in Figure 2 includes a plurality of single batteries 100, and a heat absorption sheet 20 is provided between at least two adjacent single batteries 100. In this case, the battery assembly 200 can specifically be a battery pack, or a battery module or a module-less battery pack. Among them, in the above-mentioned battery assembly 200, a plurality of single batteries 100 can be connected in series, in parallel or in combination to form a battery module. A plurality of single batteries 100 can be packaged together by the same outer shell frame and connected to the outside through a unified boundary. Among them, when the battery assembly 200 shown in Figure 2 is specifically a battery pack, it can also include a battery pack tray and an upper cover (not shown in the figure).

[0048] In some embodiments of the present application, referring again to FIG. 2 , a battery assembly includes a plurality of battery cells 100 arranged along a first direction (i.e., the left-right direction in FIG. 2 ). A heat sink 20 is disposed between any two adjacent battery cells 100 arranged along the first direction. In FIG. 2 , the heat sink 20 is disposed between the opposing large surfaces 10a of any two adjacent battery cells 100. In some embodiments of the present application, the first direction (i.e., the left-right direction in FIG. 2 ) is the thickness direction of the housing of the battery cells 100. That is, the plurality of battery cells 100 are arranged along the thickness direction of the housing of the battery cells, and the heat sink 20 is disposed on one or both surfaces of the housing of the battery cells in this thickness direction.

[0049] In this embodiment of the present application, the battery cells 100 and the heat absorbing sheets 20 are arranged alternately along a first direction. That is, adjacent battery cells 100 are separated by the heat absorbing sheets 20, and adjacent heat absorbing sheets 20 are separated by the battery cells 100. If the battery cells 100 are denoted as A and the heat absorbing sheets 20 are denoted as B, their arrangement can be BABAB...AB, ABAB...A, and so on.

[0050] Because the heat sink 20 disposed between at least some adjacent single cells 100 in the battery assembly 200 satisfies the aforementioned relationship, when thermal runaway occurs in one or more single cells, the heat diffusion / heat spread thereof is fully suppressed by the heat sink, preventing it from affecting adjacent cells. This ensures that the battery assembly 200 is relatively safe while still being able to output energy to electrical equipment. Furthermore, the volume of the heat sink 20 within the battery assembly 200 is relatively small, resulting in a high space utilization rate for the battery assembly, ensuring that it can provide a high amount of power to electrical equipment and demonstrating outstanding market competitiveness.

[0051] The present application also provides a device comprising the battery assembly described above. The device may be a power-consuming device, such as a vehicle (e.g., a ship or vehicle), a consumer electronics product (e.g., a mobile phone or tablet), or an energy storage system. The vehicle may be a pure electric vehicle, a hybrid electric vehicle, or an extended-range electric vehicle.

[0052] The technical solution of the present application is further described below with reference to a number of specific embodiments.

[0053] Example 1

[0054] A square single battery with a mass of 0.89 kg, a ternary 811 cell type, and a shell size of: length a' of 148 mm, width b' of 97 mm, and thickness c' of 28 mm.

[0055] The thermal runaway triggering conditions of the single cell are: room temperature (25℃±2℃), 100% SOC, and single cell puncture triggering. A thermocouple is placed on the single cell to collect temperature. After thermal runaway, the mass of the cell is weighed to obtain the mass m res , the heat generation Q of the thermal runaway battery is obtained by accelerated calorimetry (ARC) gen , the maximum temperature of the battery surface during thermal runaway T face , the maximum temperature at the explosion-proof valve T max (See Table 1) and the ambient temperature T of the thermal runaway battery en (Specifically, 40°C). In addition, the specific heat capacity c of the single cell was measured. cell It is 1.1kJ / (kg·K).

[0056] Selected specific heat capacity c absThe main heat-absorbing material (specifically hydrogel) is 4.2 kJ / (kg·K). The gel polymer material is mixed with water and coated on a substrate to form a sheet material of a certain thickness. After cutting into corresponding length and width dimensions, the required heat-absorbing sheet is formed (dimensions are shown in Table 1). The heat-absorbing sheet is heat-sealed with PET film on all sides. The phase change latent heat H of the main heat-absorbing material in the heat-absorbing sheet is tested by DSC method. p 1600kJ / kg, phase transition temperature T p The temperature is 118℃. In addition, the density of the heat absorbing sheet is ρ, which is 1030kg / m 3 According to the above relationship provided in this application, the upper limit value (ie 400×S1×c'×ρ) and the lower limit value (ie X) of the mass of the heat absorbing sheet are calculated, and the specific usage value within this range is determined, see Table 1.

[0057] Five of the above-mentioned single cells were sequentially arranged and assembled into a battery pack, and then a battery pack was formed. The above-mentioned heat-absorbing sheet was placed between adjacent single cells. The mass of the main heat-absorbing material in each heat-absorbing sheet in each embodiment is shown in Table 1. Within the same embodiment, the mass of the main heat-absorbing material in each heat-absorbing sheet was equal. A needle penetration test was then conducted, and the results are shown in Table 1. The needle penetration test steps included: after fully charging each single cell, a 3mm diameter steel needle was used to penetrate the middle of the middle single cell (i.e., the third single cell in the five sequentially arranged single cells) at a speed of 0.5mm / s until thermal runaway occurred. The test was then stopped and observed until the collected temperature was less than 100°C. After the test, it was recorded whether the adjacent cells experienced thermal runaway (the thermal runaway criterion was a voltage drop to zero and the explosion-proof valve opened), that is, whether heat diffusion occurred.

[0058] Examples 2-5 and Comparative Examples 1-2:

[0059] Referring to Example 1, single cells and battery packs of other examples and comparative examples were prepared, with specific differences shown in Table 1. Specific test methods for each parameter are detailed in the detailed description of the embodiment.

[0060] Table 1

[0061] Table 1 shows that when the dimensions and mass of the heat sink placed between the individual cells meet the relationship required by this application, the heat sink effectively suppresses heat diffusion from the individual cells to the adjacent cells during thermal runaway. However, a comparison between Comparative Example 1 and Example 1, and between Comparative Example 2 and Example 2, shows that when the heat sink does not meet the aforementioned relationship, it is unable to suppress heat diffusion from the battery experiencing thermal runaway. Furthermore, when the dimensions of the battery and heat sink are identical but the battery types are different, the relationship between the dimensions and mass of the heat sink satisfies the relationship provided by this application. This demonstrates the universality of the relationship provided by this application.

[0062] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present application. It should be noted that a person skilled in the art may make various modifications and improvements without departing from the scope of the present application, and all such modifications and improvements fall within the scope of protection of the present application.

Claims

1. A battery assembly (100'), comprising a single battery (100) and a heat absorbing sheet (20); the single battery (100) comprising a housing, the housing being square, the heat absorbing sheet (20) being provided on one side surface of the housing; an explosion-proof valve being provided on the single battery (100); wherein, The heat absorbing sheet (20) comprises a heat absorbing main material, and the mass m0 of the heat absorbing main material in g satisfies the following relationship: X≤m0≤400×S1×c'×ρ, X=1000×[k×Q gen -m res ×c cell ×(T face -40)-(m cell -m res )×c cell ×(T max -40)-2m cell ×c cell ×(T p - 40)] / [H p +c abs ×(T p -40)]; where k = 1.1 / (1+c' / b'+c' / a'); Among them, m cell 、m res are respectively the mass of the single battery (100) before and after thermal runaway, both in kg; T face 、T max They are respectively used to set the maximum temperature of the surface of one side of the heat absorbing plate (20) during the thermal runaway process and the maximum temperature of the explosion-proof valve during the thermal runaway process, both in units of °C; c cell is the specific heat capacity of the single battery (100), the unit is kJ / (kg·K); Q gen The heat generated by the single cell (100) during thermal runaway is measured based on the accelerating calorimetry method, in kJ; T p 、H p 、c abs are the phase change temperature, latent heat of phase change and specific heat capacity of the heat absorbing main material, respectively, and the units are ℃, kJ / kg, and kJ / (kg·K) respectively; ρ is the density of the heat absorbing sheet (20), and the unit is kg / m 3 ; S1 is the orthographic projection area of the heat absorbing plate (20) on the surface of the side of the housing on which the heat absorbing plate (20) is provided, in m 2 a' and b' are respectively the length and width of the side surface of the shell on which the heat absorbing plate (20) is set, both in m; c' is the dimension of the shell in a direction perpendicular to the side surface, in m. 2 . The battery assembly according to claim 1 , wherein a′≥b′>c′.

3. The battery assembly according to claim 1 or 2, wherein the ratio of the length of the heat absorbing sheet (20) in meters to the a' is between 0.5 and 1.

4. The battery assembly according to any one of claims 1 to 3, wherein the ratio of the width of the heat absorbing sheet (20) in meters to the width b' is between 0.5 and 1.

5. The battery assembly according to any one of claims 1 to 4, wherein the thickness of the heat absorbing sheet (20) is greater than or equal to 0.0002 meters.

6. The battery assembly according to any one of claims 1 to 5, wherein the thickness of the heat absorbing sheet (20) is less than or equal to 0.5 c'.

7. The battery assembly according to any one of claims 1 to 6, wherein the battery assembly (100') satisfies at least one of the following (1) to (4): (1) H p Greater than or equal to 500kJ / kg; (2) T p In the range of 85℃-180℃; (3) T max Greater than 300℃; (4) Q gen Greater than 400kJ.

8. The battery assembly according to any one of claims 1 to 7, wherein the heat-absorbing main material comprises at least one of a hydrogel and a hydrated salt.

9. The battery assembly according to any one of claims 1 to 8, wherein the heat absorbing sheet (20) comprises a substrate and the heat absorbing main material supported on the substrate.

10. The battery assembly according to any one of claims 1 to 9, wherein the surface of the heat absorbing sheet (20) is further covered with a sealing film.

11. The battery assembly according to any one of claims 1 to 10, wherein the shell has a first side surface and a second side surface arranged opposite to each other in the thickness direction, and at least one of the first side surface and the second side surface is provided with the heat absorption sheet (20); a', b', and c' are respectively the length, width, and thickness of the shell, all in units of m, and a'≥b'>c'.

12. The battery assembly according to any one of claims 1 to 11, wherein the battery assembly (100') comprises a plurality of the single batteries (100), and the heat absorption sheet (20) is provided between at least two adjacent single batteries (100).

13. The battery assembly according to any one of claims 1 to 12, wherein the battery assembly (100') comprises a plurality of the single batteries (100) arranged along a first direction, and wherein the heat absorbing sheet (20) is provided between any two adjacent single batteries (100) in the plurality of the single batteries (100) arranged along the first direction.

14. The battery assembly according to claim 13, wherein the first direction is a thickness direction of the shell of the single battery (100).

15. A device comprising the battery assembly according to any one of claims 1 to 14, wherein the device is an electrical device or an energy storage system.

Images