Battery assembly and power apparatus

Abstract

A power apparatus, comprising a battery assembly. The battery assembly comprises Q battery units arranged in sequence, wherein a heat-absorbing member is provided between any two adjacent battery units, each battery unit comprises N cells arranged in sequence, Q≥2, and N≥1. By controlling the mass of a heat-absorbing member to satisfy a relational expression defined in the present application, it can be ensured 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 power devices

[0001] This application claims priority to Chinese Patent Application No. 202411216162.9, filed on August 30, 2024, entitled "Battery Component and Device", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of battery technology, specifically to a battery module and a power device. Background Technology

[0003] Individual battery cells are prone to internal short circuits and thermal runaway under conditions such as continuous overcharging, impact, or puncture. This can spread to neighboring cells. To suppress heat propagation during thermal runaway, the industry typically applies flame-retardant media (such as aerogel) to the surface of the battery casing. However, aerogel can only delay heat transfer and cannot effectively absorb the large amounts of heat released from the battery's interior, thus failing to effectively block the thermal spread of thermal runaway cells. Therefore, it is necessary to develop a technical solution that can effectively block the thermal spread of thermal runaway cells. Summary of the Invention

[0004] In view of this, this application provides a battery module and a power device to solve the problem that abnormal heat generation in individual cells in existing battery modules cannot be effectively suppressed and diffused.

[0005] Specifically, the first aspect of this application provides a battery assembly, including Q battery cells arranged sequentially, with a heat-absorbing element disposed between any two adjacent battery cells, each battery cell including N individual cells arranged sequentially, where Q≥2 and N≥1; wherein, the heat-absorbing element includes a heat-absorbing main material, and the heat-absorbing main material includes a heat-absorbing material; wherein, a battery cell adjacent to the heat-absorbing element and the heat-absorbing element satisfy the following relationship:

[0006] (0.6×T 平衡 -28) / [H p +c abs ×(T p -T en )]≤m≤(3×T 平衡 -140) / [H p +c abs ×(T p -T en )];

[0007] Among them, T 平衡 T represents the temperature at which the temperature drop of N individual cells in the battery cell reaches equilibrium during thermal runaway, in °C. enThe ambient temperature of the heat-absorbing element is in °C; m is the mass of the main heat-absorbing material in kg; H p c abs T p The terms are the latent heat of phase change, specific heat capacity, and phase change temperature of the heat-absorbing material, respectively, in kJ / kg, kJ / (kg·K), and ℃.

[0008] In this battery assembly, a heat-absorbing element is set between adjacent battery cells. The mass of the heat-absorbing main material in the heat-absorbing element is designed based on its heat absorption characteristics and the heat transferred to the heat-absorbing element by a single cell in the adjacent battery cell that has experienced thermal runaway. By controlling the mass of the heat-absorbing main material in the heat-absorbing element to satisfy the above relationship, it can effectively ensure that the heat generated by the single cell in the battery cell that has experienced thermal runaway is fully absorbed by the heat-absorbing element, effectively suppress the heat diffusion to the adjacent battery cells, ensure the safety of the overall battery assembly, and at the same time ensure that the effective space utilization rate of the battery assembly is high, avoiding the heat-absorbing element occupying too much volume.

[0009] Secondly, this application provides an electrical device including the battery assembly described in the first aspect of this application, the electrical device including electrical appliances or energy storage systems. Attached Figure Description

[0010] Figure 1A shows an exemplary structural schematic diagram of a battery assembly provided in an embodiment of this application;

[0011] Figure 1B shows another exemplary structural schematic diagram of the battery assembly provided in the embodiments of this application;

[0012] Figure 2 is a schematic diagram of a single-cell battery with heat-absorbing elements on its surface provided in an embodiment of this application;

[0013] Figure 3 is a schematic diagram of a heat-absorbing element provided in an embodiment of this application;

[0014] Figure 4 is a schematic diagram of one structure of the heat-absorbing main material in Figure 3. Detailed Implementation

[0015] The technical solutions of the embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0016] This application provides a battery assembly. Referring to Figures 1A and 1B, the battery assembly 1000 provided in this application includes Q battery cells 100 arranged sequentially, each battery cell 100 including N individual cells 10 arranged sequentially, where Q ≥ 2 and N ≥ 1; a heat-absorbing element 200 is disposed between any two adjacent battery cells 100. Figure 1A shows an example with Q = 5 and N = 1. Figure 1B shows an example with Q = 3 and N = 2.

[0017] The heat-absorbing element 200 includes a heat-absorbing main material (not shown in Figures 1A and 1B), which includes a heat-absorbing material; wherein, a battery cell adjacent to the heat-absorbing element satisfies the following relationship with the heat-absorbing element:

[0018] (0.6×T 平衡 -28) / [H p +c abs ×(T p -T en )]≤m≤(3×T 平衡 -140) / [H p +c abs ×(T p -T en )];

[0019] Among them, T 平衡 T represents the temperature at which the temperature drop of N individual cells 10 in battery cell 100 reaches equilibrium during thermal runaway, expressed in °C. en The ambient temperature at which the single cell 10 experiences thermal runaway is expressed in °C; m represents the mass of the heat-absorbing main material, expressed in kg; H p c abs T p The terms are the latent heat of phase change, specific heat capacity, and phase change temperature of the heat-absorbing material, respectively, in kJ / kg, kJ / (kg·K), and ℃.

[0020] In the above relation, [H p +c abs ×(T p -T en [)] This reflects the heat absorption capacity of the heat-absorbing main material per unit mass, and its product with m represents the total heat that the heat-absorbing main material can absorb. Considering that the heat transferred from a single cell undergoing thermal runaway to the side of the heat-absorbing component through the battery cell is affected by the test environment and test conditions, the inventors discovered through numerous experiments that (0.6×T 平衡 -28) can reflect the minimum heat value transferred by N individual cells 10 in a battery cell 100 adjacent to the heat absorber 200 during thermal runaway through the battery cell 100 toward the side of the heat absorber 200 (that is, the side of the individual cell 10 in the battery cell 100 adjacent to the heat absorber 200 toward the heat absorber 200, denoted as the first surface 10a). Among them, (3×T 平衡 -140) can reflect the maximum heat transferred through the first surface 10a by the N individual cells 10 in the battery cell 100 that have experienced thermal runaway; these values ​​were discovered by the inventors of this application through extensive experimental research, thus eliminating the need to test the heat generation of each individual cell 10 during the thermal runaway process. Therefore, (0.6×T) 平衡-28) / [H p +c abs ×(T p -T en This reflects the minimum mass of the required heat-absorbing material, expressed in kg (3×T). 平衡 -140) / [H p +c abs ×(T p -T en [)] can reflect the maximum value of the required heat-absorbing material in kg.

[0021] This application controls the actual mass m of the heat-absorbing main material (in kg) to be greater than or equal to the minimum value of the aforementioned mass. This effectively ensures that the heat generated by the N individual cells 10 in a battery cell 100 adjacent to the heat-absorbing component 200 during thermal runaway can be effectively absorbed, preventing a chain reaction of thermal runaway that could affect adjacent battery cells 100, thereby ensuring better safety of the battery assembly 1000. This application also controls the actual mass m of the heat-absorbing main material (in kg) to be less than or equal to the maximum value of the aforementioned mass. This allows the volume ratio of the heat-absorbing component 200 within the battery assembly 1000 to be smaller, thus enabling a larger number of individual cells 10 to be contained within a given volume of the battery assembly 1000. This results in higher space utilization and a larger output power of the battery assembly 1000.

[0022] Furthermore, the relationship satisfied by the aforementioned heat-absorbing element 200 is universal and can be applied to the fabrication of heat-absorbing elements on various types, models, and shapes of single-cell batteries. For example, the single-cell battery may include, but is not limited to, lithium batteries, sodium batteries, potassium batteries, zinc batteries, etc. The shape of the single-cell battery 10 may be square, hexagonal prism, or irregularly shaped.

[0023] In this embodiment, when the mass of the heat-absorbing main material satisfies the aforementioned relationship defined in this application, the percentage of the thickness of a single heat-absorbing element 200 to the thickness of its adjacent battery cell (i.e., the sum of the thicknesses of the individual cells 10 contained in that battery cell) in the battery assembly 1000 does not exceed 20%. This allows the battery assembly 1000 to contain a larger number of individual cells 10, resulting in higher space utilization and greater power output. In some embodiments, this thickness percentage is below 19%, below 16%, or even below 13%.

[0024] The above relationship (0.6×T) 平衡 -28) / [H p +c abs ×(T p -T en )]≤m≤(3×T 平衡 -140) / [H p +c abs×(T p -T en In the calculation, the parameters are not calculated without units. For example, "c abs "Specific heat capacity of the heat-absorbing material, in kJ / (kg·K)" refers to c abs The value for heat-absorbing materials is expressed in kJ / (kg·K).

[0025] In this application, (0.6×T) can be used. 平衡 -28) / [H p +c abs ×(T p -T en The lower limit of the mass m of the heat-absorbing main material in kg is called (3×T). 平衡 -140) / [H p +c abs ×(T p -T en The mass m of the heat-absorbing main material, expressed in kg, is referred to as the upper limit of this mass. It is understood that in this application, the mass m of the heat-absorbing main material, expressed in g, satisfies: (600 × T) 平衡 -28000) / [H p +c abs ×(T p -T en )]≤m≤(3000×T 平衡 -140000) / [H p +c abs ×(T p -T en )).

[0026] In this application, the sign of "thermal runaway" in a single cell 10 can be that the voltage of the single cell 10 drops to 0 and its explosion-proof valve opens. In some embodiments, the thermal runaway process refers to the process in which the temperature of the single cell 10 rapidly rises from room temperature and then decreases until it returns to room temperature when it experiences thermal runaway.

[0027] In this application, after the heat-absorbing material of the heat-absorbing element 200 is determined, the specific heat capacity c of the heat-absorbing material is... abs These are inherent parameters of the heat-absorbing material and can be obtained by consulting textbooks. For example, when the heat-absorbing material is a hydrogel, c abs The phase transition temperature T of the endothermic material is 4.2 kJ / (kg·K). p Phase transition latent heat H pThis can be obtained through differential scanning calorimetry (DSC). Specifically, a preset mass m1 of heat-absorbing material can be taken from the heat-absorbing element 200, and the temperature T at which this preset mass of heat-absorbing material undergoes a phase transition during the temperature rise process can be recorded. p Test its performance during phase transition, at times greater than T p 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 endothermic material during a phase change, based on H / m1. This gives the latent heat of phase change H of the endothermic material. p Furthermore, the DSC testing scheme utilizes proprietary testing equipment, such as a differential scanning calorimeter (DSC). The mass m of the heat-absorbing material can be obtained by first separating it from the heat-absorbing element 200 and weighing it.

[0028] The above T 平衡 It can be measured under adiabatic conditions. Specifically, Q battery cells are arranged along a first direction. When the battery cell 100 includes a single cell 10, the single cell has two opposite sides along the first direction, both of which are denoted as surfaces 10a' (essentially the aforementioned first surface 10a). A battery cell (i.e., a single cell) is taken out from the battery assembly, and n thermocouples (n≥2) are evenly arranged on the two surfaces 10a' of the single cell. Then, the single cell 10 is placed in an adiabatic container (e.g., made of a heat-insulating material with good heat insulation performance) that has almost no heat exchange with the surrounding environment. The explosion-proof valve of the single cell 10 can be used as a spray valve in case of thermal runaway. To induce thermal runaway, the single cell 10 is punctured or heated. The temperature of the single cell 10 initially rises rapidly, then slowly decreases. When the temperature drop rate of the last of the 2n temperature measuring points on the two surfaces 10a' reaches 1 ± 0.05℃ / min, the temperature drop of the single cell 10 is considered to have reached equilibrium. The temperatures of the 2n measuring points at this point are obtained, and their average value is taken to obtain T. 平衡 .

[0029] In some embodiments, the individual battery 10 is a square battery, with the first direction parallel to the thickness direction of the individual battery, and the aforementioned surface 10a' can be the large surface of the individual battery 10. The large surface of the individual battery 10 is the side with the largest area in the square housing. For example, as shown in FIG1A, the battery assembly 1000 includes five battery cells 100 arranged sequentially, each battery cell 100 containing one individual battery 10. The middle individual battery 10 can be removed, and the aforementioned thermocouples can be arranged on the two large surfaces of this individual battery 10. In other embodiments, the individual battery 10 is a square battery, and the first direction can also be parallel to the length or width direction of the individual battery 10. It is understood that the individual battery 10 can also be a cylindrical battery, and the battery cells can be arranged radially along the cylindrical battery, in which case the aforementioned thermocouples can be arranged on the circumferential surface of the cylindrical battery.

[0030] When the battery unit 100 includes N individual cells 10 (N≥2), the N individual cells 10 are arranged sequentially along a first direction. One of the two individual cells 10 located at both ends in the first direction is designated as the first cell, and the other is designated as the Nth cell. Both the first cell and the Nth cell have two sides arranged opposite each other in the first direction, wherein the side of the first cell facing away from the Nth cell and the side of the Nth cell facing away from the first cell are both designated as surface 10a (which is essentially the first surface 10a of the first cell and the Nth cell, respectively). A battery unit is taken out from the battery assembly, and n thermocouples (n≥2) are evenly arranged on the surface 10a of the first cell and the Nth cell of the battery unit, respectively. Then, the N individual cells 10 in the battery unit are placed in an insulated container with almost no heat exchange with the surrounding environment. The explosion-proof valve of each individual cell 10 can be used as a spray valve in case of thermal runaway. To induce thermal runaway, the N individual cells 10 are punctured or heated. The temperature of each cell 10 initially rises rapidly and then slowly decreases. When the temperature drop rate of the last of the 2n temperature measuring points (where thermocouples are arranged on the two surfaces 10a) reaches 1 ± 0.05 °C / min, the temperature drop of the N individual cells in the battery unit is considered to have reached equilibrium. The temperatures of the 2n measuring points at this point are obtained, and their average value is taken to obtain T. 平 Balance.

[0031] In some embodiments, the individual battery 10 is a square battery, with the first direction parallel to the thickness direction of the individual battery 10. The two surfaces 10a” mentioned above can be the large surfaces of the first battery and the Nth battery, respectively, and the large surfaces of the first battery and the Nth battery are the sides with the largest area in the square casings of these two individual batteries. For example, as shown in FIG1B, the battery assembly 1000 includes three battery units 100, each battery unit including two individual batteries. The middle battery unit 100 can be removed, and the aforementioned thermocouples are provided on the left large surface of the individual battery on the left and the right large surface of the individual battery on the right.

[0032] In other embodiments, the single cell 10 is a square cell, and the first direction can also be parallel to the length or width direction of the single cell 10. It is understood that the single cell 10 can also be a cylindrical cell, and the first direction can be parallel to the radial direction of the cylindrical cell. In this case, the aforementioned thermocouples can be arranged on the arc surfaces of the first cell and the Nth cell, which are opposite to each other. For example, n can specifically be 3, 4, 6, 8, 9, 10, 12, 15, 16, 18, 20, etc. The time it takes for the temperature drop of the single cell to reach equilibrium (calculated from the start of thermal runaway) can be 2000s, 3000s, or 4000s, etc.

[0033] The above T en This refers to the ambient temperature at which the heat-absorbing element 200 is located. Generally, T... en The temperatures can be 20℃, 30℃, 35℃, or 40℃, etc. It should be noted that the ambient temperature of the heat-absorbing material is essentially the same as that of the heat-absorbing component (or battery assembly, battery cell). Therefore, for ease of testing, the ambient temperature of the heat-absorbing component reflects the ambient temperature of the heat-absorbing material.

[0034] In some embodiments of this application, the positive electrode of the single cell 10 may include one or more of layered oxide positive electrode materials and lithium manganese iron phosphate materials. Layered oxide positive electrode materials have relatively poor safety, making them particularly suitable for using the formula described above in this application to calculate the mass of the heat-absorbing element disposed between single cells using layered oxide positive electrode materials, thus ensuring that abnormal heat generation in the single cell can be effectively absorbed by the heat-absorbing element. Taking lithium batteries as an example, their layered oxide positive electrode materials refer to lithium oxides containing at least one non-lithium metal element, and those containing two or more non-lithium metal elements are more common. Furthermore, based on the type of non-lithium metal element, the layered oxide positive electrode material can be classified into monolithic oxide positive electrode materials, binary oxide positive electrode materials, ternary oxide positive electrode materials, multi-component oxide positive electrode materials, etc. Exemplarily, commonly used layered oxide positive electrode materials for lithium batteries include, but are not limited to, lithium nickel cobalt manganese oxide (e.g., LiNi). 0.8 Co 0.1 Mn 0.1O2 (abbreviated as NFM811), LiNi 0.5 Co 0.3 Mn 0.2 O2 (abbreviated as NCM532), lithium nickel cobalt aluminum oxide, lithium nickel cobalt manganese aluminum oxide, lithium nickel cobalt oxide, lithium nickel manganese oxide, etc.

[0035] In some embodiments, Q battery cells and N individual cells are arranged sequentially along a first direction, and each battery cell contains the same number of individual cells. For individual cells 10 that are square, in the battery assembly 1000 of this application, the Q battery cells 100 can be arranged sequentially along the first direction, with a heat-absorbing element 200 disposed between adjacent battery cells 100. This first direction is parallel to the thickness direction of the heat-absorbing element 200 or the thickness direction of the individual cell 10. Specifically, the heat-absorbing element 200 is disposed on the side of the battery cell 100 perpendicular to the first direction. For a battery cell comprising N (N≥2) individual cells, these N battery cells are also arranged sequentially along the first direction. In the overall battery assembly 1000, multiple individual cells 10 are also arranged along the first direction. Of course, it is understood that in other embodiments, the arrangement directions of the Q battery cells and N individual cells can also be different; for example, the Q battery cells can be arranged along the length or width direction of the individual cell, and the N individual cells can be arranged along the thickness direction of the individual cell.

[0036] In some embodiments of this application, if the individual battery 10 is designated as A and the heat absorber 200 as B, and if each battery cell 100 includes N=1 individual batteries, and any two adjacent battery cells 100 are separated by the heat absorber 200, then along the aforementioned first direction, the arrangement of the individual batteries 10 and the heat absorber 200 can be ABAB…A (as shown in Figure 1A), or ABAB…AB, etc. In this case, all individual batteries 10 in the battery assembly 1000 are separated by the heat absorber 200 from any two adjacent individual batteries 10. The heat absorber 200 is disposed between the first surfaces 10a of any two adjacent individual batteries 10. That is, the individual batteries 10 and the heat absorber 200 are arranged alternately along the first direction. A heat-absorbing element 200 is provided between any two adjacent individual cells 10, which can ensure that the safety performance of any battery assembly 1000 is good. It is especially suitable for battery assemblies 1000 composed of individual cells 10 with poor safety performance, such as battery systems using ternary cathode materials.

[0037] Similarly, in other embodiments of this application, if the individual battery 10 is designated as A and the heat absorber 200 as B, and if each battery cell 100 includes N=2 individual batteries 10, and any two adjacent battery cells 100 are separated by the heat absorber 200, then along the aforementioned first direction, the arrangement of the individual batteries 10 and the heat absorber 200 can be AAB-AAB…AA (as shown in Figure 1B), etc. In this case, among the multiple individual batteries 10 of the battery assembly 1000, some adjacent pairs of individual batteries 10 are provided with a heat absorber 200, while other adjacent pairs of individual batteries 10 are not provided with a heat absorber 200. As shown by the arrow in Figure 1B along the first direction, there is no heat absorber between the 1st and 2nd individual batteries, between the 3rd and 4th individual batteries, and between the 5th and 6th individual batteries. This situation is particularly suitable for battery assemblies composed of individual batteries with relatively high safety performance, such as batteries using phosphate materials as the positive electrode material.

[0038] It should be noted that the number N of individual cells in each battery unit can be equal or unequal. Figures 1A and 1B above illustrate this with equal N. An example of "unequal N" is as follows: In the battery assembly 1000, the arrangement of individual cells and the heat absorber can be AB-AAB-AAAB-AB, etc. When the number of individual cells in the battery units on both sides of the heat absorber is different, the battery unit containing the most individual cells and the heat absorber satisfy (0.6×T) 平衡 -28) / [H p +c abs ×(T p -T en )]≤m≤(3×T 平衡 -140) / [H p +c abs ×(T p -T en That's it.

[0039] In some embodiments of this application, the single cell 10 is a square cell with a square casing. The first surface 10a can specifically be the large surface of the square casing, that is, the side with the largest area in the square casing of the single cell 10. Referring to Figure 2, Figure 2 is a structural schematic diagram of a single cell with heat-absorbing elements disposed on its surface provided in an embodiment of this application.

[0040] The single-cell battery 10 in Figure 2 is a square battery. This single-cell battery 10 includes a square casing, with a heat-absorbing element 200 disposed on the large surface of the casing. In Figure 2, a' and b' are the length and height of the first surface of the casing where the heat-absorbing element 200 is disposed, respectively. c' is the dimension of the casing on the side surface perpendicular to the heat-absorbing element 200, and c' can be referred to as the width of the casing of the single-cell battery 10. The plane formed by the length a' and height b' of the casing is the large surface of the casing, and the plane formed by the height b' and width c' is the small surface of the casing. Generally, a' ≥ b' > c'.

[0041] The casing of the aforementioned single battery can be any casing well known to those skilled in the art. In some embodiments, the casing can be a metal casing, such as an aluminum casing or a steel casing. Of course, in other embodiments, the casing can also be an aluminum-plastic film. The casing can accommodate the cell assembly (not shown in Figure 2). Furthermore, the single battery 10 also has a positive electrode post 101 and a negative electrode post 102 exposed on the top of the casing. Of course, the positive and negative electrode posts can also be located at opposite ends of the single battery, such as at both ends along the length of the single battery. The cell assembly generally includes multiple positive electrode plates and multiple negative electrode plates, and adjacent positive and negative electrode plates can be separated by a separator or a semi-solid / all-solid electrolyte material. Accordingly, the single battery 10 can be a liquid battery, or an all-solid battery or a semi-solid battery. The positive electrode post 101 of the single battery 10 can be electrically connected to the positive electrode plate, and the negative electrode post 102 can be electrically connected to the negative electrode plate. These two posts can serve as electrode leads during charging and discharging of the single battery 10.

[0042] In this application, the heat-absorbing element 200 can be sheet-like, with a thickness less than its lateral dimension. In this case, the heat-absorbing element can also be referred to as a "heat-absorbing sheet". The thickness direction of the heat-absorbing element 200 is perpendicular to the first surface 10a of the single-cell battery 10. The smaller thickness of the sheet-like heat-absorbing element facilitates greater space utilization in the battery assembly containing multiple single-cell batteries 10. The cross-sectional shape of the heat-absorbing element 200 can be a regular rectangle, pentagon, hexagon, or other irregular shape. In some embodiments, the cross-sectional shape of the heat-absorbing element 200 is rectangular (as shown in Figure 2), consistent with the shape of the casing. In Figure 2, the thickness c of the heat-absorbing element 200 is much smaller than its length a and its width b. The thickness c of the heat-absorbing element 200 is also much smaller than the casing width c' of the single-cell battery 10. Furthermore, the length a of the heat-absorbing element 200 can be less than, equal to, or greater than the length a' of the casing, and the width b of the heat-absorbing element 200 can be less than, equal to, or greater than the height b' of the casing. Figure 2 illustrates the case of "less than".

[0043] In one embodiment of this application, the side of a single battery cell 10 adjacent to the heat absorber 200 facing the heat absorber 200 is designated as the first surface 10a. The ratio of the area of ​​the surface of the heat absorber 200 in contact with the first surface 10a of the single battery cell (e.g., denoted as S1) to the area of ​​the first surface 10a (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 0.8-1. By setting the ratio between the contact areas of the heat absorber 200 and the first surface 10a of the single battery cell within this range, it can be ensured that the heat absorber 200 fully contacts the first surface 10a, thereby ensuring a good heat absorption effect of the heat absorber 200. Preferably, the area of ​​the surface of the heat absorber 200 in contact with the first surface 10a is equal to the area of ​​the first surface 10a, so that the heat absorber 200 completely absorbs the heat transferred from the first surface of the single battery cell adjacent to the heat absorber.

[0044] In one embodiment of this application, the side of a single cell 10 adjacent to the heat absorber 200 facing the heat absorber 200 is designated as the first surface 10a. The distance between the geometric center (point E) of the surface of the heat absorber 200 in contact with the first surface 10a and the geometric center (point F) of the first surface 10a is less than or equal to 1 mm and greater than or equal to 0. That is, the distance between points E and F is within the range of greater than or equal to 0 and less than or equal to 1 mm. This ensures that the heat absorber 200 does not deviate too much from the first surface 10a, thereby improving the heat absorption effect of the heat absorber.

[0045] In this embodiment of the application, referring to Figure 3, the heat-absorbing component 200 may include a heat-absorbing main material 21 and an encapsulating film 22. The encapsulating film 22 has a receiving cavity 221 formed inside, and the heat-absorbing main material 21 is disposed within this cavity 221. The presence of the encapsulating film 22 enhances the protective function of the heat-absorbing main material 21, preventing leakage or detachment of the effective components within the heat-absorbing main material 21. The encapsulating film 22 may be selected from one or more of PP (polypropylene), PET (polyethylene terephthalate), PI (polyimide), TPU (thermoplastic polyurethane elastomer), and aluminum-plastic film. These materials have a certain degree of flexibility, allowing the encapsulating film 22 to adhere tightly to the surface of the heat-absorbing main material 21, providing good protection. In some embodiments, the encapsulating film 22 may be rectangular, and its two sides or all four sides may be sealed by heat sealing. Furthermore, the thickness of the encapsulating film 22 can be designed according to actual needs. In one embodiment, the encapsulating film 22 may be very lightweight, and the weight of the heat-absorbing main material 21 may be similar to the weight of the heat-absorbing component 200. The mass of the heat-absorbing main material 21 can be considered as the mass of the heat-absorbing element 200. In another embodiment, the mass of the encapsulation film 22 may be close to or greater than the mass of the heat-absorbing main material; in this case, only the mass of the heat-absorbing main material is calculated. Furthermore, when the mass of the encapsulation film 22 is less than 10% of the mass of the heat-absorbing main material, for ease of measurement, the mass of the heat-absorbing element can be considered as the mass of the heat-absorbing main material.

[0046] In some embodiments of this application, referring to FIG4, the heat-absorbing main material 21 includes a skeleton 210 and a heat-absorbing material 212. The skeleton 210 has a plurality of holes 211 penetrating the skeleton along the thickness direction, and the heat-absorbing material 212 fills the holes 211. In this case, the heat-absorbing material 212 is the effective component of the heat-absorbing main material 21 for absorbing heat. The H of the aforementioned heat-absorbing main material 21... p Specifically, the H of the heat-absorbing material 212 p The skeleton 210 serves to support and shape the heat-absorbing material 212, and the skeleton 210 can be made of a mesh polymer material.

[0047] In this application, the heat-absorbing material 212 is a composite material containing a liquid phase change medium. The heat absorption effect is achieved by utilizing the phase change of this liquid phase change medium. The liquid phase change medium includes at least one liquid such as water, ethanol, and ethylene glycol. In some embodiments of this application, the heat-absorbing material 212 can be a water-containing hydrogel, a water-containing hydrated salt, or a complex thereof. The phase change temperature can be adjusted by controlling the water content in the heat-absorbing material 212. The complex can be a composite of a hydrogel or hydrated salt with other materials (such as flame retardants). Taking a hydrogel as an example, a polymer material with a network structure can be used as the matrix of the hydrogel, and water as the liquid phase change medium. In other embodiments of this application, the heat-absorbing material 212 can be a material containing liquids such as ethanol or ethylene glycol.

[0048] In this embodiment, the phase transition temperature of the heat-absorbing material 212 can be in the range of 85℃-180℃. The thermal runaway initiation temperature of the single cell 10 is usually within this temperature range, and the phase transition temperature of the heat-absorbing material is also within this range. This allows the material to rapidly absorb heat and remove heat at the beginning of thermal runaway in the single cell 10, thus suppressing heat diffusion. Specifically, the phase transition temperature can be 90℃, 100℃, 110℃, 120℃, 130℃, 140℃, 150℃, 160℃, 170℃, etc.

[0049] In the embodiments of this application, the latent heat of phase change H of the heat-absorbing material 212 p It can be above 500 kJ / kg. This ensures that the heat-absorbing main material has a high heat absorption capacity, better suppressing the heat generation and diffusion of thermal runaway single cells. In some embodiments of this application, the latent heat of phase change H of the heat-absorbing material 212... p Within the range of 500 kJ / kg to 2200 kJ / kg. Under these conditions, the heat-absorbing material 212 exhibits high heat absorption capacity and is readily available. Specifically, the H... p 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.

[0050] In other embodiments of this application, the heat-absorbing main material 21 does not include a framework; the heat-absorbing main material 21 may simply be the aforementioned heat-absorbing material. The aforementioned heat-absorbing material may be directly encapsulated in the encapsulation film 22. Exemplarily, the heat-absorbing main material may be the aforementioned hydrogel, hydrated salt, or a composite thereof.

[0051] In one embodiment of this application, whether the heat-absorbing main material includes a frame 210 and a heat-absorbing material 212, or the heat-absorbing main material 21 only includes a heat-absorbing material 212, the heat-absorbing main material is located inside the encapsulation film 22 to achieve sealing and prevent the heat-absorbing material from undergoing a phase change and reducing the quality of the heat-absorbing material, so as to ensure the heat absorption effect of the heat-absorbing material.

[0052] In this embodiment of the application, the battery assembly 1000 can be a battery module or a battery pack. Within the battery assembly 1000, multiple individual cells 10 can be connected in series, parallel, or a combination thereof to form a battery pack. Multiple individual cells 10 can also be encapsulated together within the same housing frame, communicating with the outside through a unified boundary.

[0053] This application also provides an electrical device that includes the battery assembly described in the embodiments of this application. The electrical device may include electrical appliances or energy storage systems, etc.

[0054] The exemplary electrical equipment includes, but is not limited to, vehicles (such as ships, vehicles, etc.) or 3C products (such as mobile phones, tablets, smart bracelets, etc.). Exemplary vehicles may be pure electric vehicles, hybrid electric vehicles, range-extended electric vehicles, electric buses, electric trucks, etc. Energy storage systems may be site energy backup systems, intelligent photovoltaic energy storage power stations, etc.

[0055] The technical solution of this application will be further described below with reference to several specific embodiments.

[0056] Example 1

[0057] Five individual cells are arranged sequentially along their thickness, and a heat-absorbing element is placed between the large faces of any two adjacent cells to obtain a battery assembly. The ambient temperature T in which the heat-absorbing element is located is measured. en The details are recorded in Table 1. In this battery assembly, the arrangement of the individual cells (denoted as A) and the heat absorber (denoted as B) is ABABABABA, or (AB)4A. That is, the battery assembly of Example 1 includes 5 battery units, each of which includes one square single lithium battery cell, as shown in Table 1. Its casing dimensions are 160mm × 90mm × 30mm (i.e., length a' is 160mm, height b' is 90mm, and width c' is 30mm). The positive electrode material of this single battery cell is ternary material NCM811; the mass of the single battery cell (i.e., the battery unit) is 0.95kg.

[0058] The preparation method of the heat-absorbing element includes: selecting a gel polymer material, mixing it with water, coating it onto a PET substrate, and then curing it to form a specific heat capacity c. abs A hydrogel with a heat transfer efficiency of 4.2 kJ / (kg·K) was peeled off from a PET substrate and cut into corresponding sizes to obtain m kg of hydrogel (i.e., the main heat-absorbing material is this hydrogel). The main heat-absorbing material was then heat-sealed around its edges with 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 H of the heat-absorbing material in the heat-absorbing sheet was measured using the DSC method. p 1400 kJ / kg, phase transition temperature T p The temperature is 108℃.

[0059] Get T 平衡 To select another single cell (the number of selected single cells is equal to the number of single cells in the battery cell in this embodiment), its T is tested. 平衡The selected individual cell is the same as the individual cell in the aforementioned battery assembly. Thus, the T of this selected individual cell... 平衡 Compared with the T of the single cell in this embodiment 平衡 Same. T 平衡 The testing method is the same as described above. Specifically, nine thermocouples are evenly arranged on two large surfaces of the selected single cell for temperature acquisition. The single cell is then placed in an insulated container with almost no heat exchange with the surrounding environment, and an opening is made at the explosion-proof valve of the single cell to act as a spray valve. The single cell is punctured to induce thermal runaway. After thermal runaway, the temperature of the single cell first rises rapidly and then slowly decreases. When the temperature drop rate of the last temperature measuring point among the 18 thermocouples on the single cell reaches 1 ± 0.05℃ / min, the temperature drop of the single cell is considered to have reached equilibrium. The temperatures of the 18 measuring points at this point are obtained, and their average value is taken to obtain T. 平衡 The specific values ​​are shown in Table 1.

[0060] Based on the aforementioned relationship provided in this application, the upper and lower limits of the heat-absorbing main material's mass can be calculated, as shown in Table 1. Comparison reveals that the actual mass m of the heat-absorbing main material in Example 1 falls between these upper and lower limits.

[0061] In addition, the thickness of each heat absorber in the above-mentioned battery assembly was measured, and the ratio of it to the thickness of the battery cell (that is, the sum of the widths (thicknesses) of all the individual cells contained therein) is summarized in Table 1.

[0062] The battery assembly was also subjected to a needle penetration test, which included the following steps: At room temperature, after each individual cell was fully charged, a steel needle with a diameter of 3 mm was used to puncture the middle position of the individual cell in the middle battery unit (i.e., the cell in the 3rd battery unit, that is, the 3rd individual cell in the 5 cells arranged in sequence) at a speed of 0.5 mm / s until the cell caused thermal runaway and then stopped. The observation continued until the temperature of the cell that caused thermal runaway was less than 100°C. After the experiment, it was recorded whether the adjacent cells had thermal runaway (the criteria for thermal runaway is voltage drop or the opening of the explosion-proof valve), that is, whether thermal diffusion occurred.

[0063] 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, 2 and 3.

[0064] In Examples 7-8, 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.

[0065] In the battery packs of Examples 4, 11, 12, and Comparative Examples 4 and 5, the arrangement of the individual cells (denoted as A) and the heat absorber (denoted as B) is AABAABAABAABAA, or (AAB)4AA. That is, such a battery pack includes 5 battery cells, and each battery cell includes 2 square individual lithium batteries.

[0066] Obtain T in Example 4 平衡 In this case, two additional individual cells are selected (i.e., the number of additional individual cells is equal to the number of individual cells in the battery cell of this embodiment), and these are the same as the individual cells in the battery cell of this embodiment. Thus, the T of these two selected individual cells... 平衡 Compared with the T of the individual cells in the battery cell of this embodiment 平衡 Same. Among them, T 平衡 The testing method is the same as described above. Specifically, nine thermocouples are evenly arranged on the large surfaces of the two selected individual cells, arranged sequentially along the thickness direction and facing away from each other, to collect temperature data. These two individual cells are then placed in an insulated container with almost no heat exchange with the surrounding environment. The explosion-proof valve of each individual cell is opened to function as a spray valve. The two individual cells are punctured to induce thermal runaway. After thermal runaway, the temperature of the two individual cells first rises rapidly and then slowly decreases. When the temperature drop rate of the last of the 18 temperature measuring points on the two individual cells reaches 1 ± 0.05℃ / min, the temperature drop of the two individual cells is considered to have reached equilibrium. The temperatures of the 18 measuring points at this point are obtained, and their average value is taken to obtain T. 平衡 The specific values ​​are shown in Table 1. T values ​​for Examples 11-12 and Comparative Examples 4-5 are also shown. 平衡 The acquisition method is the same as described above, and will not be repeated here. The specific values ​​are shown in Tables 2 and 3.

[0067] Table 1

[0068] Table 2

[0069] Table 3

[0070] As can be seen from the tables above, 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 of a single cell to the adjacent cell. At the same time, the thickness of the heat-absorbing sheet and the adjacent battery cell is relatively low, not exceeding 20%, thereby making the total thickness ratio of all heat-absorbing sheets in the overall battery assembly low and the effective space utilization rate of the battery assembly high.

[0071] As can be seen from the comparison between Comparative Examples 1-2 and Example 1, the mass of the heat-absorbing sheet in Comparative Example 2 is less than the lower limit of the above-mentioned relationship in this application, and it cannot suppress the thermal diffusion of the thermal runaway battery in the battery assembly. In Comparative Example 1, the actual mass of the heat-absorbing sheet is greater than the upper limit of the above-mentioned relationship in this application. Although thermal runaway battery thermal diffusion did not occur in the battery assembly, the thickness ratio between the heat-absorbing sheet and the adjacent battery cell is large, affecting the space utilization efficiency of the individual cells in the battery assembly. A similar phenomenon is observed in the comparison between Comparative Examples 4-5 and Example 4. Furthermore, the comparison between Comparative Example 3 and Example 2 also exhibits a similar phenomenon to the comparison between Comparative Example 2 and Example 1.

[0072] The embodiments described above are merely examples of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these modifications and improvements all fall within the protection scope of this application.

Claims

1. A battery assembly (1000), characterized in that, The battery unit comprises Q sequentially arranged battery cells (100), with a heat-absorbing element (200) disposed between any two adjacent battery cells (100). Each battery cell (100) comprises N sequentially arranged individual cells (10), where Q≥2 and N≥1. The heat-absorbing element (200) comprises a heat-absorbing main material (21), which in turn comprises a heat-absorbing material (212). A battery cell (100) adjacent to the heat-absorbing element (200) satisfies the following relationship with the heat-absorbing element (200): (0.6×T) 平衡 -28) / [H p +c abs ×(T p -T en )]≤m≤(3×T 平衡 -140) / [H p +c abs ×(T p -T en )]; Among them, T 平衡 The temperature at which the temperature drop of N individual cells (10) in the battery cell (100) reaches equilibrium during thermal runaway is represented by the temperature in °C. T en The ambient temperature of the heat-absorbing element (200) is expressed in °C. m is the mass of the heat-absorbing main material (21), in kg; H p c abs T p The latent heat of phase change, specific heat capacity, and phase change temperature of the heat-absorbing material (212) are respectively expressed in kJ / kg, kJ / (kg·K), and ℃.

2. The battery assembly (1000) as claimed in claim 1, characterized in that, The positive electrode of the single cell (10) includes one or more of layered oxide positive electrode materials and lithium manganese iron phosphate materials.

3. The battery assembly (1000) as described in claim 1 or 2, characterized in that, The H p Greater than or equal to 500 kJ / kg.

4. The battery assembly (1000) as described in any one of claims 1-3, characterized in that, The H p Within the range of 500-2200 kJ / kg.

5. The battery assembly (1000) according to any one of claims 1-4, characterized in that, The side of a single cell (10) adjacent to the heat absorber (200) facing the heat absorber (200) is designated as the first surface (10a). The ratio of the surface area of ​​the heat absorber (200) in contact with the first surface (10a) to the area of ​​the first surface (10a) is greater than or equal to 0.8 and less than or equal to 1.

6. The battery assembly (1000) according to any one of claims 1-5, characterized in that, The side of the heat absorber (200) adjacent to the heat absorber (200) facing the heat absorber (200) is designated as the first surface (10a). The distance between the geometric center of the surface of the heat absorber (200) in contact with the first surface and the geometric center of the first surface (10a) is less than or equal to 1 mm and greater than or equal to 0.

7. The battery assembly (1000) according to any one of claims 1-6, characterized in that, The heat-absorbing component (200) also includes an encapsulation film (22), the encapsulation film (22) having a receiving cavity (221) inside, and the heat-absorbing main material (21) being disposed in the receiving cavity (221).

8. The battery assembly (1000) according to any one of claims 1-7, characterized in that, The heat-absorbing main material (21) includes a skeleton (210) and the heat-absorbing material (212). The skeleton (210) has a plurality of holes (211) penetrating the skeleton (210) along the thickness direction of the skeleton (210), and the heat-absorbing material (212) fills the holes (211).

9. The battery assembly (1000) according to any one of claims 1-7, characterized in that, The heat-absorbing main material (21) is the heat-absorbing material (212).

10. The battery assembly (1000) according to any one of claims 1-9, characterized in that, The phase transition temperature T of the heat-absorbing material (212) p The temperature range is 80℃-180℃.

11. The battery assembly (1000) according to any one of claims 1-10, characterized in that, The heat-absorbing material (212) is a hydrogel, a hydrated salt, or a composite thereof.

12. The battery assembly (1000) according to any one of claims 1-11, characterized in that, The Q battery cells (100) and N individual cells (10) are arranged sequentially along the first direction, and each battery cell (100) contains the same number of individual cells (10).

13. The battery assembly (1000) according to any one of claims 1-12, characterized in that, The single cell (10) is a square cell, and the heat-absorbing element (200) is disposed on the side of the battery cell (100) perpendicular to the thickness direction of the single cell (10).

14. An electric device, characterized in that, Includes the battery assembly (1000) as described in any one of claims 1-13, wherein the power device includes an electrical appliance or an energy storage system.

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