Battery assembly and device

Abstract

A battery assembly and a device. The battery assembly comprises a plurality of single batteries, and heat-absorbing members are provided between oppositely arranged first surfaces of at least some adjacent single batteries. Each heat-absorbing member comprises a main heat-absorbing material, the main heat-absorbing material comprises a heat-absorbing material, and the latent heat Hp of phase change of the heat-absorbing material is greater than or equal to 500 kJ / kg. The mass m of the main heat-absorbing material in kg satisfies the following relational expression: 0.5Q / (α×Hp)≤m≤1.5Q / (α×Hp).

Description

Battery components and devices

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on December 29, 2023, with application number 202311872174.2 and invention name “Battery Components and Devices”, the entire contents of which are incorporated by reference into this application. Technical Field

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

[0003] Continuous overcharging, collisions, or punctures can easily cause internal short circuits in single cells, leading to thermal runaway and potentially affecting adjacent cells. To suppress the spread of heat during thermal runaway in single cells, the industry typically places a flame retardant (such as aerogel) on the surface of the cell's casing. However, aerogel can only slow the transfer of heat and cannot effectively absorb the large amount of heat released within the battery, making it difficult to effectively block the thermal diffusion of batteries experiencing thermal runaway. Therefore, it is necessary to develop a technical solution that can effectively block the thermal diffusion of single cells experiencing thermal runaway.

[0004] Summary of the Invention

[0005] In view of this, the present disclosure provides a battery assembly and a device to solve the problem that abnormal heat generation of single cells in existing battery assemblies cannot be effectively suppressed and diffused.

[0006] Specifically, the first aspect of the present disclosure provides a battery assembly, comprising a plurality of single cells, wherein a heat absorbing member is provided between first surfaces of at least some adjacent single cells that are arranged opposite to each other; wherein the heat absorbing member comprises a heat absorbing main material, the heat absorbing main material comprises a heat absorbing material, and the phase change latent heat H of the heat absorbing material is p Greater than or equal to 500 kJ / kg; wherein the mass m of the heat absorbing main material in kg satisfies the following relationship: 0.5Q / (α×H p )≤m≤1.5Q / (α×H p ),

[0007] Q represents the heat transferred from the single cell adjacent to the heat sink through the first surface during thermal runaway, in kJ; α represents the correction factor; wherein, when H p In the range of 500-1000 kJ / kg, α is 1.3; when H p In the range of greater than 1000 kJ / kg to less than or equal to 1600 kJ / kg, α is 1.2; when H p In the range of greater than 1600 kJ / kg to less than or equal to 2400 kJ / kg, α is 1.15; when H pWhen it is greater than 2400 kJ / kg, α is 1.1.

[0008] The quality of the main heat-absorbing material in the heat-absorbing elements disposed between at least some adjacent single cells in the battery assembly is designed based on their heat absorption characteristics and the amount of heat dissipated from the adjacent surfaces of the thermal runaway battery and adjacent cells. Controlling at least some of the heat-absorbing elements to satisfy the aforementioned relationship effectively ensures that heat generated abnormally by one or more single cells is fully absorbed by the heat-absorbing elements, effectively suppressing heat diffusion to adjacent cells, thereby ensuring the safety of the entire battery assembly. This also ensures high effective space utilization within the battery assembly and prevents the heat-absorbing elements from occupying excessive volume.

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

[0010] FIG1A is a schematic diagram of an exemplary structure of a battery assembly provided in an embodiment of the present disclosure.

[0011] FIG1B is another exemplary structural diagram of a battery assembly provided in an embodiment of the present disclosure.

[0012] FIG2 is a schematic structural diagram of a single battery provided with a heat absorbing element on the surface according to an embodiment of the present disclosure.

[0013] FIG3 is a schematic diagram of a calorimetric test of a single cell using a thermal balance calorimetry method.

[0014] FIG4 is a schematic structural diagram of a heat absorbing element provided in an embodiment of the present disclosure.

[0015] FIG5 is a schematic structural diagram of the heat-absorbing main material in FIG4 .

[0016] FIG6 is a structural block diagram of a device provided by an embodiment of the present disclosure. DETAILED DESCRIPTION

[0017] The technical solutions of the embodiments of the present disclosure are described in detail below with reference to the accompanying drawings.

[0018] The present disclosure also provides a battery assembly. Referring to FIG. 1A and FIG. 1B , the battery assembly 300 provided by the present disclosure includes a plurality of single cells 100, with a heat absorbing member 20 disposed between at least some adjacent single cells 100. The heat absorbing member 20 is disposed between the first surfaces 10a of two adjacent single cells 100. The heat absorbing member 20 includes a heat absorbing main material (not shown in FIG. 1A and FIG. 1B ), which includes a phase change latent heat H p Heat absorbing material greater than or equal to 500 kJ / kg; wherein the mass m of the heat absorbing main material in kg satisfies the following relationship: 0.5Q / (α×Hp )≤m≤1.5Q / (α×H p ),

[0019] Q represents the heat transferred from a single battery 100 adjacent to the heat sink 20 through the first surface 10a during thermal runaway, in kJ; α represents the correction factor; wherein, when H p In the range of greater than 500 kJ / kg to less than or equal to 1000 kJ / kg, α is 1.3; when H p In the range of greater than 1000 kJ / kg to less than or equal to 1600 kJ / kg, α is 1.2; when H p In the range of greater than 1600 kJ / kg to less than or equal to 2400 kJ / kg, α is 1.15; when H p When it is greater than 2400 kJ / kg, α is 1.1.

[0020] The introduction of α in the above relationship can truly reflect the heat absorption capacity of the main heat-absorbing material. Specifically, the present disclosure has determined based on a large number of experiments that there is a difference between the heat that can be absorbed by the heat-absorbing component and the heat that the single battery adjacent to the heat-absorbing component transfers through its first surface during thermal runaway. Therefore, in order to more accurately obtain the mass range of the main heat-absorbing material in the heat-absorbing component, the present disclosure determines the true heat absorption capacity of the main heat-absorbing material by determining a correction factor. Furthermore, the present disclosure has learned through a large number of experiments that as the phase change latent heat Hp of the heat-absorbing material in the main heat-absorbing material gradually increases, the heat absorption capacity of the heat-absorbing material becomes stronger, and therefore the heat that can be absorbed per unit mass is relatively more, but the heat absorption efficiency of the heat-absorbing material decreases. Therefore, it is necessary to adjust the mass of the heat-absorbing material to achieve heat absorption, and then make the correction factor α gradually decrease as the phase change latent heat Hp of the heat-absorbing material gradually increases, so as to ensure that the heat absorption capacity of the main heat-absorbing material is closer to reality. Further, the present disclosure has determined through a large number of experiments that when H p In the range of greater than 500 kJ / kg to less than or equal to 1000 kJ / kg, α is 1.3; when H p In the range of greater than 1000 kJ / kg to less than or equal to 1600 kJ / kg, α is 1.2; when H p In the range of greater than 1600 kJ / kg to less than or equal to 2400 kJ / kg, α is 1.15; when H p When it is greater than 2400 kJ / kg, α is 1.1, which can more accurately estimate the mass of the main heat-absorbing material, so that it can ensure that the heat-absorbing component can achieve its heat absorption capacity under actual working conditions, and avoid the thermal runaway of a single cell affecting the thermal runaway of adjacent single cells.

[0021] The above Q can also represent the amount of heat that needs to be absorbed by the heat absorbing element 20, so Q / (α×H p ) can reflect the theoretical limit mass m of the heat absorbing main material极 The present invention controls the phase change latent heat H of the heat absorbing main material. p Above 500kJ / kg, it can ensure that it has a high ability to absorb the heat generated by the thermal runaway battery and control the mass m of the heat-absorbing main material to 0.5m 极 and 1.5m 极 The amount of the main heat-absorbing material can better meet the actual needs, which can effectively ensure that the heat generated abnormally by a certain single cell 100 is effectively absorbed and the chain thermal runaway phenomenon caused by heat diffusion is suppressed, and the volume of the heat-absorbing component can be smaller, so that a battery assembly 300 of a certain volume can contain a larger number of single cells 100, and the space utilization rate of the battery assembly 300 is higher and the output power is larger.

[0022] Among them, when m is less than 0.5m 极 When m is greater than 1.5m 极 When the amount of the heat absorbing main material used is too much, its thickness will be thicker, so that the thickness of the heat absorbing member 20 is also correspondingly thicker, reducing the space utilization rate of the single battery in the battery assembly.

[0023] The main heat-absorbing material in the heat-absorbing element 20 disposed between at least some adjacent cells 100 in the battery assembly 300 satisfies the aforementioned relationship. Therefore, if thermal runaway occurs in one or more cells 100, the heat diffusion or spread is fully suppressed by the heat-absorbing element 20, preventing it from spreading to adjacent cells. This ensures the safety of the battery assembly 300 while still enabling energy output to the device. Furthermore, the aforementioned relationship minimizes the overall volume of the heat-absorbing element 20 within the battery assembly 300, resulting in high space utilization within the battery assembly 300, ensuring a high power output for the device and outstanding market competitiveness.

[0024] In addition, the relationship satisfied by the heat absorbing member 20 is universal and can be applied to the production of heat absorbing members on various single cells of different systems, models, and shapes. For example, the single cells may include but are not limited to lithium batteries, sodium batteries, potassium batteries, zinc batteries, etc. The shape of the single cell 100 may be square, blade-shaped, hexagonal, or special-shaped. It is understood that in the present disclosure, the mass m of the heat absorbing main material in g satisfies: 500Q / (α×H p )≤m≤1500Q / (α×H p ).

[0025] In this disclosure, Q represents the amount of heat transferred from a single cell 100 adjacent to the heat sink 20 through its first surface 10a during thermal runaway. "Thermal runaway" of a single cell can be understood as the voltage of the single cell 100 dropping to zero and the explosion-proof valve opening. In the embodiments of the present disclosure, the thermal runaway process is defined as the period from before thermal runaway of a single cell to the end of thermal runaway. Specifically, "before thermal runaway of a single cell" means that the temperatures measured by any two thermocouples on the surface of the single cell are consistent before thermal runaway occurs. Generally, the temperature measured by any two thermocouples on the surface of the single cell is at room temperature before thermal runaway occurs. For example, the temperatures measured by any two thermocouples on the surface of the single cell are both 25°C ± 5°C. "End of thermal runaway" means the moment, after a period of time after thermal runaway occurs, when the temperatures measured by any two thermocouples on the surface of the single cell return to consistency. In some embodiments, the thermal runaway process refers to the period during which the temperature of a single cell adjacent to the heat sink rises from room temperature and then returns to room temperature while experiencing thermal runaway. Furthermore, in some embodiments, the surface of the single battery is the first surface of the single battery adjacent to the heat absorption element.

[0026] In some embodiments of the present disclosure, any two adjacent single cells 100 within a battery assembly 300 may be separated by a heat sink 20 (as shown in FIG1A ). The heat sink 20 is disposed between the first surfaces 10a of any two adjacent single cells 100. That is, the single cells 100 and the heat sink 20 are arranged alternately along a first direction parallel to the thickness of the heat sink 20. Providing a heat sink between any two adjacent single cells ensures better safety performance for any battery assembly. This is particularly suitable for battery assemblies composed of single cells with inherently poor safety performance, such as battery systems using a ternary positive electrode material for the positive electrode. If the single cell 100 is denoted as A and the heat sink 20 is denoted as B, their arrangement can be ABAB…AB (as shown in FIG1A ), or ABAB…A, etc.

[0027] In other embodiments of the present disclosure, among the multiple single cells within a battery assembly 300, some adjacent single cells 100 may have a heat sink 20 disposed between them, while other adjacent single cells 100 may not have a heat sink disposed between them (as shown in FIG1B ). This arrangement is particularly suitable for battery assemblies comprised of single cells with relatively high inherent safety performance, such as batteries using phosphate-based positive electrode materials. If the single cells 100 are denoted as A and the heat sink 20 as B, their arrangement along the thickness direction parallel to the heat sink can be, for example, AAB-AAB...AAB (as shown in FIG1B ), AAAB-AAAB...AAAB, or AB-AAB-AAB..., etc., but is not limited thereto.

[0028] The above-mentioned first surface 10a is the adjacent and opposite surface of two adjacent single cells. In some embodiments of the present disclosure, the single cell 100 is a square battery having a square shell. The first surface 10a can specifically be the large surface 10a of the square shell, that is, the side with the largest area in the square shell of the single cell 100. Referring to Figure 2, Figure 2 is a structural schematic diagram of a single cell with a heat-absorbing element provided on the surface provided by an embodiment of the present disclosure. The single cell 100 in Figure 2 is a square battery, and the single cell 100 includes a square shell 10, and a heat-absorbing element 20 is provided on the large surface 10a of the shell 10. It can be understood that the shell 10 includes two large surfaces 10a arranged opposite to each other and two small surfaces 10b arranged opposite to each other. The two large surfaces 10a are connected by the small surfaces 10b respectively, and the two large surfaces 10a and the two small surfaces 10b form a square shell 10. In FIG2 , a′>b′>c′; the plane formed by the length a′ and the height b′ of the housing 10 is the large surface 10a of the housing, and the plane formed by the height b′ and the width c′ of the housing 10 is the small surface 10b of the housing.

[0029] The shell 10 can be a shell familiar to those skilled in the art, for example, the shell 10 is an aluminum-plastic shell. The shell 10 can accommodate a battery cell assembly (not shown in FIG2 ). In addition, the single cell 100 also has a positive electrode column 101 and a negative electrode column 102 exposed on the top of the shell 10. The battery cell assembly generally includes a plurality of positive electrode sheets and a plurality of negative electrode sheets, and the adjacent positive electrode sheets and negative electrode sheets can be separated by a diaphragm or a semi-solid / all-solid electrolyte material. Accordingly, the single cell 100 can be a liquid battery, or an all-solid battery or a semi-solid battery. The positive electrode column 101 of the single cell 100 can be electrically connected to the positive electrode sheet, and the negative electrode column 102 can be electrically connected to the negative electrode sheet. These two columns can serve as electrical contact points when the single cell 100 is charged and discharged.

[0030] In the present disclosure, the heat sink 20 may be in the form of a sheet, with a thickness less than its transverse dimension. In this case, the heat sink may also be referred to as a "heat sink sheet." The thickness of the heat sink 20 is perpendicular to the first surface 10a of the battery cell 100. The reduced thickness of the sheet-shaped heat sink facilitates greater space utilization in a battery assembly comprising multiple battery cells 100. The cross-sectional shape of the heat sink 20 may be a regular rectangle, pentagon, hexagon, or other irregular shape. In some embodiments, the cross-sectional shape of the heat sink 20 is rectangular (as shown in FIG. 2 ), consistent with the shape of the housing 10. In FIG. 2 , the thickness c of the heat sink 20 is significantly less than its length a and width b. The thickness c of the heat sink 20 is also significantly less than the width c' of the housing 10. Furthermore, the length a of the heat sink 20 may be less than, equal to, or greater than the length a' of the housing 10, and the width b of the heat sink 20 may be less than, equal to, or greater than the height b' of the housing 10. FIG. 2 illustrates the "less than" case.

[0031] In this disclosure, the above parameter H p The heat release rate can be obtained by performing a differential scanning calorimetry (DSC) test on the heat absorbing element 20. Specifically, a predetermined mass m1 of the heat absorbing material in the heat absorbing element 20 can be taken out, and the total heat H released by the predetermined mass of the heat absorbing material during the phase change during the temperature rise process can be measured. The heat released by the phase change per unit mass of the heat absorbing material can be obtained by dividing H / m1 (m1 is the predetermined mass of the heat absorbing material in the heat absorbing element 20, such as 50g, 100g, 150g, etc.), that is, the phase change latent heat H of the heat absorbing material can be obtained. p In addition, the Dsc testing program features proprietary testing equipment, such as a differential scanning calorimeter (DSC).

[0032] In the present disclosure, the above-mentioned Q is measured based on the thermal balance calorimetry method. See Figure 3, which is a schematic diagram of a calorimetric test of a single cell using the thermal balance calorimetry method. In the thermal balance calorimetry method, a single cell 100 and two heat-conducting containers 30 filled with high heat capacity material (the high heat capacity material is not shown in Figure 3) are placed in an insulating container 200, and the two first surfaces 10a of the single cell 100 are respectively attached to the side walls of the two heat-conducting containers 30, triggering thermal runaway of the single cell 100 and testing Q. Wherein, Q = M × c2 × ΔT, M represents the initial total mass of the high heat capacity material in one heat-conducting container 30, in kg, c2 represents the specific heat capacity of the high heat capacity material, in kJ / (kg·K); ΔT represents the temperature rise of the high heat capacity material during the thermal runaway process of the single cell 100, in °C. It can be understood that the heat Q measured by the above-mentioned test method is the heat transferred from one first surface 10a of the single cell.

[0033] Since Q is measured based on thermal balance calorimetry, the mass of the main heat-absorbing material in the heat-absorbing element 20 is indirectly calculated based on this method. Specifically, the heat generated by a thermal runaway battery cell 100 can be conducted through its first surface to the thermally conductive container 30, which then conducts the heat to the internal high-heat-capacity material. The above Q = M × c² × ΔT also intuitively reflects the amount of heat absorbed by the high-heat-capacity material from the first surface on the side of the thermally runaway battery cell close to the adjacent battery cell. Based on the measured precise amount of heat absorbed by the high-heat-capacity material, Q, the amount of the main heat-absorbing material in the heat-absorbing element that can absorb this heat is calculated. This ensures that the heat-absorbing element 20 can effectively absorb the abnormal heat generated by the battery cell 100 and suppress heat diffusion / propagation, thereby ensuring the safety of a battery assembly constructed from multiple battery cells without affecting the assembly efficiency of the battery assembly.

[0034] In the thermal equilibrium calorimetry test, a single cell 100 and two thermally conductive containers 30 filled with a high heat capacity material are placed in an insulating container 200 as described above. Thermal runaway is then triggered in the single cell 100, such as by needle puncture. Prior to triggering thermal runaway, two opposing thermocouples are placed in one of the thermally conductive containers 30, one adjacent to the sidewall contacting the first surface 10a of the single cell 100 and the other away from the first surface 10a of the single cell 100 (the placement of the two thermocouples is indicated by curved arrows in FIG3 ) to facilitate temperature measurement. ΔT = T2 - T1, where T1 refers to the temperature of the high heat capacity material in the single cell before thermal runaway (at which point the temperatures measured by the two thermocouples are also consistent). Generally, the single cell is at room temperature before thermal runaway, for example, the temperatures measured by the thermocouples on the surface of the single cell are both 25°C ± 5°C. T2 refers to the highest temperature at which the temperatures measured by the two thermocouples reach consistency after thermal runaway.

[0035] The above M can be determined by directly weighing or indirectly loading the high heat capacity material filled in each thermally conductive container 30. Specifically, this can be done during a thermal balance calorimetry test before triggering thermal runaway in a single cell. c2 is an inherent parameter of the selected high heat capacity material.

[0036] In the embodiment of the present disclosure, the specific heat capacity c2 of the high heat capacity material is greater than or equal to 2 kJ / (kg·K). The high heat capacity material can be a substance that is liquid at room temperature or can be liquid after a certain heat treatment, so as to ensure the accuracy of the above-mentioned T1 and T2 measurement results. Specifically, the high heat capacity material can be selected from one or more of water, glycerol, ethylene glycol, paraffin, hydrogel, etc., but is not limited thereto. These materials have high specific heat capacity values ​​and strong heat absorption capabilities, and can absorb the heat generated by the thermal runaway battery, which is convenient for indirect measurement of the heat transferred out by the thermal runaway battery through its surface opposite to the adjacent battery. Among them, water, glycerol, ethylene glycol, etc. are liquid-gas phase change materials, and paraffin, etc. are solid-liquid phase change materials. In addition, in order to facilitate the filling of the high heat capacity material, a filling port 301 is usually provided on the top of the thermal conductive container 30.

[0037] In the disclosed embodiment, the total volume of the high heat capacity material within each thermally conductive container 30 accounts for 50-99% of the volume of the thermally conductive container 30. This ensures that each thermally conductive container 30 contains an appropriate volume of high heat capacity material to effectively absorb the heat generated by the battery in thermal runaway, while also ensuring that the excessive volume of material does not obscure the temperature rise ΔT, making accurate temperature measurement impossible and thus affecting the accuracy of the aforementioned Q test results. Specifically, this volume percentage can be 55%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, etc.

[0038] In the embodiment of the present disclosure, the high heat capacity material satisfies the following conditions: 0.02×U×C≤M×c2≤0.1×U×C, where C and U represent the full charge capacity (or “nominal capacity”) and average discharge voltage (or “nominal voltage”) of the single cell 100, respectively, and the units are Ah and V, respectively. Controlling the product of the total mass M of the high heat capacity material and the specific heat capacity to satisfy the above relationship can ensure that it has a suitable temperature rise ΔT before and after the thermal runaway of the single cell 100. The suitable temperature rise can not only ensure the accuracy of the temperature rise test results, but also ensure that the probability of heat exchange with the external environment is low and that it is not completely vaporized, thereby ensuring the accuracy of the Q measurement results. In addition, the presence of the thermal insulation container 200 also helps to inhibit heat exchange between it, the heat conductive container 30 and the outside. Among them, the above C and U can be determined by reading the specifications of the single cell.

[0039] In the disclosed embodiments, the temperature rise ΔT of the high heat capacity material during thermal runaway of a single battery cell is less than or equal to 100°C. This low ΔT ensures more accurate Q test results. Specifically, the ΔT is ≤95°C, ≤90°C, ≤80°C, ≤70°C, ≤60°C, ≤50°C, ≤40°C, ≤30°C, etc. In some embodiments, the ΔT can be within the range of 20-30°C.

[0040] In the disclosed embodiment, the wall thickness of the thermally conductive container 30 is between 0.05 mm and 5 mm. This ensures that the thermally conductive container 30 has suitable mechanical properties while not being too thick to affect its ability to quickly transfer heat generated by the thermal runaway battery to the high heat capacity material placed therein, thereby enabling rapid measurement of the aforementioned Q.

[0041] In the present disclosure, the thermally conductive container 30 is made of a material with high thermal conductivity. The sidewalls of the thermally conductive container 30 that contact the battery cells 100 can withstand temperatures exceeding 500°C. For example, the sidewalls of the thermally conductive container 30 or the entire thermally conductive container 30 can be made of a metal material with good thermal conductivity (such as steel or aluminum), or a high-temperature-resistant inorganic non-metallic material, or an inorganic-organic composite material.

[0042] In the present disclosure, the insulated container 200 can be made of a material with low thermal conductivity, specifically, it can be formed by surrounding a low thermal conductivity plate. The thermal conductivity of the low thermal conductivity material is less than 0.2W / (m·K). In some embodiments of the present disclosure, the insulated container 200 is formed by surrounding an aluminum silicate plate.

[0043] In the disclosed embodiment, referring to FIG4 , a heat sink 20 may include a main heat sink material 21 and an encapsulating film 22. The encapsulating film 22 defines a cavity 221 within which the main heat sink material 21 is disposed. The encapsulating film 22 enhances the protective wrapping effect of the main heat sink material 21, preventing the effective ingredients in the main heat sink material 21 from leaking or falling out. The encapsulating film 22 may be selected from one or more materials such as PP (polypropylene), PET (polyethylene terephthalate), PI (polyimide), TPU (thermoplastic polyurethane), and aluminum-plastic film. These materials offer a certain degree of flexibility, allowing the encapsulating film 22 to adhere tightly to the surface of the main heat sink material 21, providing effective protection. In some embodiments, the encapsulating film 22 may be rectangular, with two or four sides heat-sealed. Furthermore, the thickness of the encapsulating film 22 may be tailored to actual needs. In one embodiment, the encapsulating film 22 can be very lightweight, with the mass of the main heat sink material 21 comparable to that of the heat sink 20. The mass of the main heat-absorbing material 21 can be considered as the mass of the heat-absorbing element 20. In another embodiment, the mass of the packaging film 22 may approach or exceed the mass of the main heat-absorbing material. In this case, only the mass of the main heat-absorbing material is calculated. Furthermore, when the mass of the packaging film 22 is less than 10% of the mass of the main heat-absorbing material, the mass of the heat-absorbing element can be considered as the mass of the main heat-absorbing material for ease of measurement.

[0044] In some embodiments of the present disclosure, referring to FIG5 , 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 is filled in the holes 211. In this case, the heat-absorbing material 212 is the effective component of the heat-absorbing main material 21 to exert the heat-absorbing effect. p Specifically, the H of the heat absorbing material 212 p The skeleton 210 supports and shapes the heat absorbing material 212 and can be made of a mesh polymer material.

[0045] In the present disclosure, the heat-absorbing material 212 is a composite material that retains a liquid phase change medium. The heat absorption effect is achieved by means of the phase change of the liquid phase change medium. Among them, the liquid phase change medium includes at least one of liquids such as water, ethanol, ethylene glycol, etc. In some embodiments of the present disclosure, the heat-absorbing material 212 can be a hydrogel, a hydrated salt, or a composite thereof that retains water. The phase change temperature of the heat-absorbing material 212 can be regulated by regulating the water content in the heat-absorbing material 212. Among them, the composite can be a composite of a hydrogel or a hydrated salt with other materials (such as a flame retardant), etc. Taking hydrogel as an example, a polymer material with a network structure can be used as the matrix of the hydrogel, and water can be used as the liquid phase change medium. In some other embodiments of the present disclosure, the heat-absorbing material 212 can be a material that retains a liquid such as ethanol or ethylene glycol.

[0046] In some other embodiments of the present disclosure, the main heat-absorbing material 21 does not include a skeleton and can be solely the aforementioned heat-absorbing material. The aforementioned heat-absorbing material can be directly encapsulated in the encapsulation film 22. For example, the main heat-absorbing material can be the aforementioned hydrogel, hydrated salt, or a composite thereof.

[0047] In one embodiment of the present disclosure, whether the main endothermic material includes the skeleton 210 and the endothermic material 212 or the main endothermic material 21 only includes the endothermic material 212, the main endothermic material is located in the packaging film 22 to achieve sealing and avoid phase change of the endothermic material and reduce the quality of the endothermic material, thereby ensuring the heat absorption effect of the endothermic material.

[0048] In the embodiment of the present disclosure, the phase change temperature of the above-mentioned heat-absorbing main material 21 can be in the range of 85°C-180°C. To be precise, the phase change temperature of the above-mentioned heat-absorbing material is in the range of 85°C-180°C. The thermal runaway starting temperature of the single cell 100 is usually within this temperature range. The phase change temperature of the heat-absorbing main material is also controlled to be within this range, so that it can quickly absorb heat at the beginning stage of thermal runaway of the single cell 100 to take away the heat and inhibit heat diffusion. Specifically, the phase change temperature can be 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, etc.

[0049] In one embodiment of the present disclosure, the ratio of the area of ​​the heat sink 20 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. Setting the ratio of the contact area between the heat sink and the first surface within this range ensures that the heat sink 20 fully contacts the first surface 10a, thereby ensuring good heat absorption by the heat sink 20. Preferably, the area of ​​the heat sink in contact with the first surface is equal to the area of ​​the first surface, so that the heat sink fully absorbs heat transferred from the first surface of a battery cell adjacent to the heat sink.

[0050] In one embodiment of the present disclosure, the distance between the geometric center of the surface of the heat sink 20 in contact with the first surface 10a and the geometric center of the first surface 10a is less than or equal to 1 mm and greater than or equal to 0. This arrangement ensures that the heat sink 20 does not deviate too far from the first surface 10a, thereby improving the heat absorption effect of the heat sink.

[0051] In the disclosed embodiments, the battery assembly 300 may be a battery module or a battery pack. Within the battery assembly 300, multiple battery cells 100 may be connected in series, in parallel, or in a combination thereof to form a battery pack. Multiple battery cells 100 may also be encapsulated within a common housing frame, connecting to the outside world through a unified boundary.

[0052] 6 is a block diagram of a device according to an embodiment of the present disclosure. The present disclosure also provides a device 60 comprising the battery assembly 300 according to the embodiment of the present disclosure. The device 60 may comprise an electrical device or an energy storage system.

[0053] Electricity-consuming equipment includes, but is not limited to, vehicles (such as ships, vehicles (such as new energy vehicles, buses), etc.), or 3C products (such as mobile phones, tablet computers), etc. New energy vehicles can be pure electric vehicles, hybrid vehicles, or extended-range vehicles, etc.

[0054] Among them, the energy storage system can be a site energy backup system, an intelligent photovoltaic energy storage power station, etc.

[0055] The technical solution of the present disclosure is further described below with reference to a number of specific embodiments.

[0056] Example 1

[0057] A square single battery has a shell size of 475 mm in length, 83.8 mm in height, and 14.5 mm in width. The cell type is ternary NCM811 and the battery mass is 1.3 kg. The full-charge capacity I and average discharge voltage U of the single battery are shown in Table 1.

[0058] Selected phase change latent heat H pA hydrogel with a heat absorption capacity of 1600 kJ / kg and a phase transition temperature of 118°C is used as the heat absorption material. It is coated on a PET substrate and formed into a film of a certain thickness after curing. The film is peeled off from the PET substrate and cut to obtain a heat absorption main material with a mass m of 0.12392 kg (i.e. 123.93 g). The heat absorption main material is heat-sealed with an aluminum-plastic film (with a thickness of 0.085 mm) to obtain a sheet-like heat absorption part (which can be called a "heat absorption sheet").

[0059] A plurality of the above-mentioned single cells are assembled into a battery assembly, and the above-mentioned heat absorbing sheet is placed between the large surfaces of any two adjacent single cells that are arranged opposite each other. That is, in the battery assembly, the single cells and the heat absorbing sheet are arranged in an ABAB... manner, where A represents the single cell and B represents the heat absorbing sheet.

[0060] The thermal runaway heat test of the above-mentioned single battery is performed using thermal balance calorimetry to obtain the Q value in the above-mentioned relationship. Specifically, the following steps are included:

[0061] 1) Provide two thermally conductive containers 30 filled with a high heat capacity material (specifically, water, whose specific heat capacity c2 is 4.2 kJ / (kg·K)). The thermally conductive containers are made of aluminum plates with a wall thickness of approximately 2-3 mm. The volume of each thermally conductive container occupied by the high heat capacity material is approximately 80% of the available volume of the container. Weigh the total mass M of the high heat capacity material in each thermally conductive container in kg.

[0062] 2) As shown in Figure 3, a single cell (which can be separated from the battery assembly) with a 100% SOC at room temperature is placed in a thermally insulated container 200 along with two thermally conductive containers 30 filled with a high-heat-capacity material. The two large surfaces of the cell are aligned with the sidewalls of the two thermally conductive containers. Two opposing thermocouples are placed in one of the thermally conductive containers for temperature measurement, one adjacent to the sidewall aligned with the cell's large surface and the other away from the cell's large surface. The temperature T1 of the two thermocouples is measured before thermal runaway occurs in the cell. This temperature also represents the initial temperature of the high-heat-capacity material.

[0063] 3) The single cell is then triggered to experience thermal runaway through a needle-puncture method, and the temperature T2 when the two thermocouples reach the same temperature is measured. The temperature rise ΔT of the high heat capacity material during the thermal runaway process of the single cell is obtained, where ΔT = T2 - T1. The heat Q transferred through a large surface during the thermal runaway process of the single cell is then calculated, where Q = M × c2 × ΔT.

[0064] Based on the foregoing description of this disclosure, the upper and lower limits of the mass of the heat-absorbing main material can be calculated (substituting α into the aforementioned equation as 1.2), as shown in Table 1. Comparison revealed that the actual mass m of the heat-absorbing main material lies between these upper and lower limits.

[0065] In addition, the ratio of the sum of the thicknesses (c) of all heat-absorbing sheets in the battery assembly to the sum of the widths (c') (i.e., thicknesses) of the individual cells was measured. The results are shown in Table 1. A needle penetration test was also conducted on the battery assembly, specifically comprising the following steps: after fully charging each individual cell, a 3mm diameter steel needle was used to penetrate the center of the middle individual cell at a rate of 0.5mm / s until thermal runaway occurred. The test was continued until the recorded temperature fell below 100°C. After the test, it was recorded whether adjacent cells experienced thermal runaway (thermal runaway criteria include voltage drop or explosion-proof valve opening), i.e., whether heat diffusion occurred.

[0066] According to Example 1, battery assemblies of other examples and comparative examples were prepared, and the main differences are listed in the following tables.

[0067] Among them, the H of the heat-absorbing material used in Example 7 is p The water content of the endothermic material is different from that of Example 1. When the above relationship is used, α is set to 1.15. The H of the endothermic material used in Example 8 is p It is 846.15 kJ / kg. Its water content is different from that in Example 1. When it is put into the above relationship, α is taken as 1.1.

[0068] Table 1

[0069] Table 2

[0070] Table 3

[0071] The present disclosure also provides the following comparative example 6.

[0072] The only difference between Comparative Example 6 and Comparative Example 5 is that the H of the heat absorbing material used is p It is 461kJ / kg.

[0073] Comparative Example 6 H p The value is not required in the aforementioned relationship of the present disclosure. p The lower limit of the mass of the heat-absorbing main material can be calculated by temporarily substituting α = 1.3 into the aforementioned relationship in this disclosure, resulting in a lower limit of 152.95g and an upper limit of 458.85g. However, the actual mass m of the heat-absorbing main material in Comparative Example 6 is 92.95g, which falls outside these upper and lower limits. Needle penetration tests revealed that heat diffusion occurred in the thermal runaway battery cells in Comparative Example 6.

[0074] It can be seen from the above tables that in a battery assembly, when the mass of the heat absorbing sheet arranged between adjacent single cells meets the relationship required by the present disclosure, the heat absorbing sheet can better suppress the thermal diffusion of the single cell in thermal runaway to the adjacent cell, and the total thickness of all the heat absorbing sheets in the battery assembly is relatively low. Among them, in the comparison between Comparative Examples 1-2 and Example 1, the mass of the heat absorbing sheet in Comparative Example 1 is less than the lower limit of the above relationship of the present disclosure, and it cannot suppress the thermal diffusion of the thermal runaway battery in the battery assembly; the mass of the heat absorbing sheet in Comparative Example 2 is greater than the upper limit of the above relationship of the present disclosure. Although the thermal diffusion of the thermal runaway battery does not occur in the battery assembly, the total thickness of the heat absorbing sheet in the battery assembly is relatively large, which affects its grouping efficiency. In addition, the comparison between Comparative Example 3 and Example 4, the comparison between Comparative Example 4 and Example 7, and the comparison between Comparative Example 5 and Example 8 also have similar phenomena. The heat absorbing material H used in Comparative Example 6 is p If the value is too low, the heat absorption capacity is weak, and it cannot effectively suppress the heat diffusion of the thermal runaway battery.

[0075] Furthermore, the data from Examples 1-3 demonstrate that, for battery assemblies using different types of cells, thermal runaway can be suppressed, and the volume fraction of the cell can be kept low, when the mass of the heat sink meets the aforementioned relationship defined in this disclosure. The data from Examples 3-5 demonstrate that, even when the arrangement of the cells and the heat sink is different, thermal runaway can be suppressed, and the volume fraction can be kept low, when the mass of the heat sink meets the aforementioned relationship defined in this disclosure. A comparison of Examples 3 and 6 demonstrates that, for battery assemblies using cells of different sizes and capacities, thermal runaway can be effectively suppressed, and the volume fraction of the heat sink can be kept low, when the mass of the heat sink meets the aforementioned relationship defined in this disclosure.

[0076] The above-described embodiments merely represent several implementation methods of the present disclosure. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present disclosure. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the scope of the present disclosure, all of which fall within the scope of protection of the present disclosure.

Claims

1. A battery assembly (300), wherein, It includes a plurality of single cells (100), and a heat absorber (20) is provided between the first surfaces (10a) of at least some adjacent single cells (100) that are oppositely arranged; wherein, the heat absorber (20) includes a main heat-absorbing material (21), the main heat-absorbing material (21) includes a heat-absorbing material (212), and the latent heat of phase change H of the heat-absorbing material (212) p is greater than or equal to 500 kJ / kg; wherein, the mass m of the main heat-absorbing material (21) in kg satisfies the following relational expression: 0.5Q / (α×H p ) ≤ m ≤ 1.5Q / (α×H p ), Q represents the heat transferred out through the first surface (10a) by one of the single cells (100) adjacent to the heat absorber (20) during thermal runaway, with the unit of kJ; α represents the correction factor; where when H p is in the range of greater than or equal to 500 kJ / kg to less than or equal to 1000 kJ / kg, α is 1.3; when H p is in the range of greater than 1000 kJ / kg to less than or equal to 1600 kJ / kg, α is 1.2; when H p is in the range of greater than 1600 kJ / kg to less than or equal to 2400 kJ / kg, α is 1.15; when H p is greater than 2400 kJ / kg, α is 1.

1.

2. The battery assembly (300) according to claim 1, wherein, The ratio of the surface area of the heat absorber (20) 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.

3. The battery assembly (300) according to claim 1, wherein, The distance between the geometric center of the surface of the heat absorber (20) in contact with the first surface (10a) and the geometric center of the first surface (10a) is less than or equal to 1 mm and greater than or equal to 0.

4. The battery assembly (300) according to any one of claims 1-3, wherein, The heat absorber (20) further includes a packaging film (22), and a receiving cavity (221) is formed inside the packaging film (22), and the main heat-absorbing material (21) is disposed in the receiving cavity (221).

5. The battery assembly (300) according to any one of claims 1-4, wherein, The main heat-absorbing material (21) includes a framework (210) and the heat-absorbing material (212), the framework (210) has a plurality of holes (211) penetrating through the framework (210) along the thickness direction of the framework (210), and the heat-absorbing material (212) fills the holes (211).

6. The battery assembly (300) according to any one of claims 1-4, wherein, The main heat-absorbing material (21) is the heat-absorbing material (212).

7. The battery assembly (300) according to any one of claims 1-6, wherein, The heat-absorbing material (212) is a composite material retaining a liquid phase change medium.

8. The battery assembly (300) according to claim 7, wherein, The heat-absorbing material (212) is a hydrogel, a hydrated salt or a composite thereof retaining water.

9. The battery assembly (300) according to any one of claims 1-8, wherein, The heat absorber (20) is provided between any two adjacent monomer cells (100).

10. The battery assembly (300) according to any one of claims 1-9, wherein, The heat absorber (20) is in a sheet shape, the thickness of the heat absorber (20) is less than the length and width of the heat absorber (20), and the thickness direction of the heat absorber (20) is perpendicular to the first surface (10a) of the monomer cell (100).

11. The battery assembly (300) according to any one of claims 1-10, wherein, The monomer cell (100) has a square housing; the first surface (10a) is the side surface of the square housing with the largest area.

12. The battery assembly (300) according to any one of claims 1-11, wherein, The phase change temperature of the heat-absorbing material is in the range of 85 °C - 180 °C.

13. An apparatus (60), wherein, Including the battery assembly (300) according to any one of claims 1 - 12, wherein the device (60) includes an electrical equipment or an energy storage system.

Images