Battery assembly and device

Abstract

The invention provides a battery assembly and device. In the battery assembly, the heat absorption pieces arranged between at least some adjacent single batteries are controlled to meet the relational expression defined in the invention, so that the heat absorption pieces can fully inhibit the heat diffusion of the thermal runaway battery, and the space utilization rate of the battery assembly is not obviously reduced.

Description

Technical Field

[0001] The present application relates to the technical field of batteries, and particularly relates to a battery component and a device. Background Art

[0002] In the case of continuous overcharging, or collision / stabbing of a single battery, it is easy to cause internal short circuit of the battery, thermal runaway, and affect adjacent batteries. To inhibit the heat spread during the thermal runaway of a single battery, the industry usually sets a flame retardant medium (such as aerogel, etc.) on the surface of the housing of the single battery. However, aerogel can only delay the transfer of heat and cannot effectively absorb a large amount of heat released inside the battery, and thus it is difficult to effectively block the heat diffusion of the thermally runaway battery. Therefore, it is necessary to develop a technical solution that can effectively block the heat diffusion of a thermally runaway single battery. Summary of the Invention

[0003] In view of this, the present application provides a battery component and a device to solve the problem that the abnormal heat generation of a single battery in an existing battery component cannot be effectively suppressed and diffused.

[0004] Specifically, in the first aspect of the present application, a battery component is provided, which includes a plurality of single batteries, and a heat absorber is disposed between the first surfaces of at least some adjacent single batteries that are oppositely arranged; wherein, the heat absorber includes a main heat absorbing material, the main heat absorbing material includes a heat absorbing material, and the latent heat of phase change H p of the heat absorbing material is greater than or equal to 500 kJ / kg; wherein, the mass m of the main heat absorbing material in kg satisfies the following relationship:

[0005] 0.5Q / (α×H p ) ≤ m ≤ 1.5Q / (α×H p ),

[0006] Q represents the heat transferred out through the first surface by one of the single batteries adjacent to the heat absorber during the thermal runaway process, and the unit is kJ; α represents a correction factor; wherein, when H p is in the range of 500 - 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.

[0007] The mass of the main heat-absorbing material in the heat-absorbing member provided between at least some adjacent single cells in the battery assembly is designed according to its heat-absorbing characteristics and the heat dissipation amount of the thermally out-of-control cell and the adjacent surface of the adjacent cell. By controlling at least some heat-absorbing members to satisfy the above relational expression, it can effectively ensure that the heat generated abnormally by a certain / some single cells is fully absorbed by the heat-absorbing member, effectively inhibit the heat from spreading to adjacent 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 relatively high, avoiding the heat-absorbing member occupying too large a volume.

[0008] In a second aspect, the present application provides a device including the battery assembly described in the first aspect of the present application, and the device includes an electrical equipment or an energy storage system. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1A 、 Figure 1B respectively show two exemplary structural schematic diagrams of the battery assembly provided by the embodiments of the present application.

[0010] Figure 2 is a structural schematic diagram of a single cell provided by an embodiment of the present application with a heat-absorbing member disposed on its surface.

[0011] Figure 3 shows a schematic diagram of calorimetric testing of a single cell using the heat balance calorimetry method.

[0012] Figure 4 is a structural schematic diagram of a heat-absorbing member provided by an embodiment of the present application.

[0013] Figure 5 is Figure 4 a structural schematic diagram of the main heat-absorbing material in DETAILED DESCRIPTION OF THE EMBODIMENTS

[0014] The technical solutions of the embodiments of the present application will be described in detail below with reference to the drawings.

[0015] The embodiments of the present application also provide a battery assembly. Please refer to Figure 1A and Figure 1B together. The battery assembly 300 provided by the embodiments of the present application includes a plurality of single cells 100, and a heat-absorbing member 20 is 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 that are oppositely disposed. Among them, the heat-absorbing member 20 includes a main heat-absorbing material ( Figure 1A 、 Figure 1B not shown in the figure), and the main heat-absorbing material includes a heat-absorbing material with a phase change latent heat H p greater than or equal to 500 kJ / kg; wherein, the mass m of the main heat-absorbing material in kg satisfies the following relational expression:

[0016] 0.5Q / (α×Hp ) ≤ m ≤ 1.5Q / (α × H p ),

[0017] Q represents the heat transferred out through the first surface 10a by a single cell 100 adjacent to the heat absorber during thermal runaway, with the unit of kJ; α represents the correction factor; where, when H p is in the range greater than 500 kJ / kg to less than or equal to 1000 kJ / kg, α is 1.3; when H p is in the range 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 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.

[0018] Introducing α in the above relationship can truly reflect the heat absorption capacity of the main heat-absorbing material. Specifically, the inventor determined through a large number of experiments that there is a difference between the heat that the heat absorber can absorb and the heat transferred out through its first surface by the single cell adjacent to the heat absorber during thermal runaway. Therefore, in order to more accurately obtain the mass range of the main heat-absorbing material in the heat absorber, the inventor determined the correction factor to determine the true heat absorption capacity of the main heat-absorbing material. Further, the inventor 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 is stronger, so relatively more heat can be absorbed per unit mass, 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 the correction factor α gradually decreases 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 the true value. Still further, the inventor determined through a large number of experiments that when H p is in the range greater than 500 kJ / kg to less than or equal to 1000 kJ / kg, α is 1.3; when H p is in the range 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 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, which can more accurately estimate the mass of the main heat-absorbing material, so that it can ensure that the heat absorber can achieve its heat absorption capacity under real working conditions and avoid the thermal runaway of the single cell affecting the thermal runaway of the adjacent single cell.

[0019] Among them, the above Q can also represent the heat that needs to be absorbed by the heat absorber 20, so Q / (α × H p ) can reflect the theoretical limit mass m of the main heat-absorbing material极 The present application controls the latent heat of phase change H of the main heat-absorbing material p to be above 500 kJ / kg, which can ensure its relatively high ability to absorb the heat generated by the out-of-control battery, and controls the mass m of the main heat-absorbing material between 0.5m 极 and 1.5m 极 . This can make the amount of the main heat-absorbing material better meet the actual needs. It can not only effectively ensure that the heat generated by abnormal heat generation of a single battery 100 is effectively absorbed, suppressing the chain thermal runaway phenomenon caused by thermal diffusion, but also make the volume ratio of the heat-absorbing member smaller, so that a larger number of single batteries 100 can be included in a battery assembly 300 of a certain volume, and the space utilization rate of the battery assembly 300 is higher and the output power is larger.

[0020] Among them, when m is less than 0.5m 极 , the amount of the main heat-absorbing material is insufficient to absorb the heat conducted out by the out-of-control battery through its first surface; when m is greater than 1.5m 极 , the amount of the main heat-absorbing material is excessive, and its thickness will be relatively thick, resulting in a relatively thick thickness of the heat-absorbing member 20, reducing the space utilization rate of the single battery in the battery assembly.

[0021] The main heat-absorbing material in the heat-absorbing member 20 provided between at least some adjacent single batteries 100 in the above battery assembly 300 satisfies the above relationship. In this way, when one / some single batteries 100 have a thermal runaway, its thermal diffusion / thermal spread is fully suppressed by the heat-absorbing member 20, preventing it from affecting adjacent batteries, ensuring better safety of the battery assembly 300 and still being able to output energy to electrical equipment; at the same time, the above relationship can ensure that the total volume ratio of the heat-absorbing member 20 in the battery assembly 300 is relatively small, the space utilization rate of the battery assembly 300 is relatively high, ensuring that it can provide a relatively high power to electrical equipment, and having outstanding market competitiveness.

[0022] In addition, the relationship satisfied by the above heat-absorbing member 20 is universal and can be applied to the production of heat-absorbing members on single batteries of various different systems, models, and shapes. For example, the single battery can include but is not limited to lithium batteries, sodium batteries, potassium batteries, zinc batteries, etc. The shape of the single battery 100 can be square, or it can be a blade-shaped battery, a hexagonal prism-shaped battery, or a special-shaped battery, etc. It can be understood that in the present application, the mass m of the main heat-absorbing material in g satisfies: 500Q / (α×H p ) ≤ m ≤ 1500Q / (α×H p ).

[0023] In this application, Q represents the heat transferred through the first surface 10a of a single battery cell 100 adjacent to the heat absorber during the thermal runaway process. Herein, the "thermal runaway" of a single battery cell can be understood as the voltage of the single battery cell 100 dropping to 0 and its explosion-proof valve opening. Based on the embodiments of this application, the thermal runaway process is the process from before the thermal runaway of a single battery cell to the end of the battery thermal runaway. Specifically, "before the thermal runaway of a single battery cell" means that before the thermal runaway of a single battery cell occurs, the temperatures collected by any two thermocouples on the surface of the single battery cell are the same. Generally, the temperature before the thermal runaway of a single battery cell is at room temperature. For example, the temperatures collected by the thermocouples on the surface of the single battery cell are all 25°C ± 5°C. "The end of thermal runaway" means that after the thermal runaway of a single battery cell occurs, after a period of time, the moment when the temperatures collected by any two thermocouples on the surface of the single battery cell reach the same again. In some embodiments, the thermal runaway process refers to the process in which a single battery cell adjacent to the heat absorber experiences thermal runaway, and the temperature of the single battery cell rises from room temperature and then drops back to room temperature. In addition, in some embodiments, the surface of the single battery cell is the first surface adjacent to the heat absorber.

[0024] In some embodiments of this application, among the multiple single battery cells in the battery assembly 300, any two adjacent single battery cells 100 can be separated by a heat absorber 20 (as Figure 1A shown). The heat absorber 20 is disposed between the first surfaces 10a of any two adjacent single battery cells 100. That is, the single battery cells 100 and the heat absorber 20 are arranged alternately in a first direction, and this first direction is parallel to the thickness direction of the heat absorber 20. Disposing a heat absorber between any two adjacent single battery cells can ensure better safety performance of any battery assembly formed, especially suitable for a battery assembly composed of single battery cells with relatively poor self-safety performance, such as a battery system with a ternary cathode material as the cathode. If the single battery cell 100 is denoted as A and the heat absorber 20 is denoted as B, their arrangement form can be A-B-A-B…A-B (as Figure 1A shown), or A-B-A-B…A, etc.

[0025] In other embodiments of this application, among the multiple single battery cells in the battery assembly 300, a heat absorber 20 can be provided between some adjacent two single battery cells 100, and no heat absorber is provided between some other adjacent two single battery cells 100 (as Figure 1B shown). This situation is particularly suitable for a battery assembly composed of single battery cells with relatively high self-safety performance, such as a battery with a phosphate material as the cathode material. If the single battery cell 100 is denoted as A and the heat absorber 20 is denoted as B, their arrangement form along the direction parallel to the thickness of the heat absorber can specifically be AAB-AAB…AAB (as Figure 1B), or AAAB-AAAB…AAAB, or AB-AAB-AAB…, etc., but not limited thereto.

[0026] The above-mentioned first surface 10a is the adjacent and opposite surface of two adjacent single cells. In some embodiments of the present application, the single cell 100 is a square cell, which has a square housing. Specifically, this first surface 10a may be the large surface 10a of the square housing, that is, the side surface with the largest area in the square housing of the single cell 100. See Figure 2 , Figure 2 It is a schematic structural diagram of a single cell provided by an embodiment of the present application, on the surface of which a heat-absorbing member is provided. Figure 2 In the single cell 100 in [], the single cell 100 is a square cell. The single cell 100 includes a square housing 10, and a heat-absorbing member 20 is provided on the large surface 10a of the housing 10. It can be understood that the housing 10 includes two relatively arranged large surfaces 10a and two relatively arranged small surfaces 10b. The two large surfaces 10a are respectively connected by the small surfaces 10b, and the two large surfaces 10a and the two small surfaces 10b enclose the square housing 10. Figure 2 In [], 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.

[0027] The above-mentioned housing 10 can adopt a housing well-known to those skilled in the art. For example, the housing 10 is an aluminum-plastic shell. Wherein, a battery cell assembly ( Figure 2 not shown in []) can be accommodated in the housing 10. In addition, the single cell 100 also has a positive electrode terminal 101 and a negative electrode terminal 102 exposed at the top of the housing 10. Among them, the battery cell assembly generally includes a plurality of positive electrode plates and a plurality of negative electrode plates, and the adjacent positive electrode plates and negative electrode plates can be separated by a separator or a semi-solid / full-solid electrolyte material. Correspondingly, the single cell 100 can be a liquid battery, or a full-solid battery or a semi-solid battery. Among them, the positive electrode terminal 101 of the single cell 100 can be electrically connected to the positive electrode plate, and the negative electrode terminal 102 can be electrically connected to the negative electrode plate. These two terminals can be used as the electrical contact points when the single cell 100 is charged and discharged.

[0028] In the present application, the heat-absorbing member 20 can be in the shape of a sheet, and its thickness is less than its lateral dimension. At this time, the heat-absorbing member can also be called a "heat-absorbing sheet". Among them, the thickness direction of the heat-absorbing member 20 is perpendicular to the first surface 10a of the single cell 100. The small thickness of the sheet-shaped heat-absorbing member is beneficial to the battery assembly including a plurality of the above-mentioned single cells 100 to have a large space utilization rate. Among them, the cross-sectional shape of the heat-absorbing member 20 can be a regular rectangle, pentagon, hexagon, or other irregular shapes. In some embodiments, the cross-sectional shape of the heat-absorbing member 20 is a rectangle (such as Figure 2As shown, it is consistent with the shape of the housing 10. Figure 2 In this case, the thickness c of the heat absorption member 20 is much smaller than its length a and smaller than its width b. The thickness c of the heat absorption member 20 is also much smaller than the width c' of the housing 10. In addition, the length a of the heat absorption member 20 can be smaller than, equal to, or greater than the length a' of the housing 10, and the width b of the heat absorption member 20 can be smaller than, equal to, or greater than the height b' of the housing 10. Figure 2 In the example, the case of "less than" is used.

[0029] In the present application, the above parameter H p can be obtained by performing a differential scanning calorimetry (DSC) test on the heat absorption member 20. Specifically, a preset mass m1 can be taken from the heat absorption material of the heat absorption member 20, and the total heat H released during the phase change of the preset mass of the heat absorption material during the temperature rise process can be measured. According to H / m1 (m1 is the preset mass of the heat absorption material in the heat absorption member 20, such as 50 g, 100 g, 150 g, etc.), the heat released by the phase change of the heat absorption material per unit mass can be obtained, that is, the latent heat of phase change H of the heat absorption material can be obtained. p In addition, the Dsc test scheme has a dedicated test device, such as a differential scanning calorimeter DSC.

[0030] In the present application, the above Q is measured based on the heat balance calorimetry method. Refer to Figure 3 , Figure 3 shows a schematic diagram of calorimetric testing of a single cell using the heat balance calorimetry method. In the heat balance calorimetry method, the single cell 100 and two heat conduction containers 30 filled with a high heat capacity material ( Figure 3 the high heat capacity material is not shown in the figure) are placed in the heat insulation container 200, and the two first surfaces 10a of the single cell 100 are respectively attached to the side walls of the two heat conduction containers 30, triggering the single cell 100 to have a thermal runaway, and Q is measured. Among them, Q = M × c2 × ΔT, M represents the initial total mass of the high heat capacity material in one heat conduction container 30, the unit is kg, c2 represents the specific heat capacity of the high heat capacity material, the unit is kJ / (kg·K); ΔT represents the temperature rise of the high heat capacity material during the thermal runaway of the single cell 100, the unit is °C. It can be understood that the heat Q measured by the above test method is the heat transferred from one first surface 10a of the single cell.

[0031] Since Q is measured based on heat balance calorimetry, the mass of the main heat-absorbing material in the heat-absorbing member 20 above is indirectly calculated based on heat balance calorimetry. Specifically, the heat generated by the thermal runaway of the single cell 100 can be conducted to the heat-conducting container 30 through its first surface, and then the heat-conducting container 30 conducts it to the internally placed high heat capacity material. The above Q = M × c2 × ΔT can also intuitively reflect the heat absorbed by the high heat capacity material conducted from the first surface on the side of the thermal runaway battery close to the adjacent battery. Based on the accurately measured heat absorption Q of the high heat capacity material, the dosage range of the main heat-absorbing material in the heat-absorbing member that can absorb this heat is calculated to ensure that the heat-absorbing member 20 can effectively absorb the heat generated abnormally by the single cell 100 and inhibit heat diffusion / spread, ensuring the safety of the battery assembly made of multiple single cells without affecting the grouping efficiency of the battery assembly.

[0032] Among them, in the heat balance calorimetry test, first place the single cell 100 and two heat-conducting containers 30 filled with high heat capacity materials in the heat-insulating container 200 in the manner described in the previous text of this application, and then trigger the thermal runaway of the single cell 100 by means such as acupuncture. Before triggering the thermal runaway, arrange two oppositely arranged thermocouples in one of the heat-conducting containers 30, one adjacent to the side wall in contact with the first surface 10a of the single cell 100, and the other away from the first surface 10a of the single cell 100 ( Figure 3 The arrangement positions of the two thermocouples are shown by curved arrows in the figure), so as to collect temperature. Among them, the above ΔT = T2 - T1, T1 refers to the temperature of the high heat capacity material before the thermal runaway of the single cell (at this time, the temperatures collected by the two thermocouples are also the same). Generally, the single cell is at room temperature before the thermal runaway. For example, the temperatures collected by the thermocouples on the surface of the single cell are all 25°C ± 5°C. T2 refers to the highest temperature when the temperatures collected by the two thermocouples reach the same after the thermal runaway of the single cell.

[0033] The above M can be known by directly weighing / indirectly weighing the high heat capacity materials filled in each heat-conducting container 30, specifically, it is tested before triggering the thermal runaway of the single cell in the heat balance calorimetry test. c2 is an inherent parameter of the selected high heat capacity material.

[0034] In the embodiments of the present application, 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 made liquid after a certain heat treatment, so as to ensure the accuracy of the above 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. The specific heat capacity values of these materials are relatively high, and their heat absorption capacity is strong, which can absorb the heat generated by the thermal runaway battery, facilitating the indirect measurement of the heat transferred out through the surface of the thermal runaway battery facing 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 at the top of the heat conducting container 30.

[0035] In the embodiments of the present application, within each heat conducting container 30, the total volume occupied by the high heat capacity material accounts for 50-99% of the volume of the heat conducting container 30. In this way, each heat conducting container 30 has an appropriate volume of high heat capacity material, which is convenient for ensuring that it can effectively absorb the heat generated by the thermal runaway battery, and at the same time, it will not make its temperature rise ΔT not obvious due to excessive volume ratio, resulting in inaccurate temperature measurement and affecting the accuracy of the above Q test results. Specifically, the volume ratio can be 55%, 60%, 70%, 75%, 80%, 85%, 90%, 95%, etc.

[0036] In the embodiments of the present application, the high heat capacity material satisfies: 0.02×U×C ≤ M×c2 ≤ 0.1×U×C, where C and U respectively represent the full charge capacity (or "nominal capacity") and average discharge voltage (or "nominal voltage") of the single cell 100, and the units are Ah and V respectively. Controlling the product of the total mass M of the high heat capacity material and its specific heat capacity to satisfy the above relationship can ensure that it has an appropriate temperature rise ΔT before and after the thermal runaway of the single cell 100. The appropriate temperature rise can not only ensure the accuracy of the temperature rise test result, 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 result. In addition, the presence of the heat insulation container 200 also helps to suppress the heat exchange between it and the heat conducting container 30 and the outside. Among them, both C and U can be determined by reading the specification of the single cell.

[0037] In the embodiments of the present application, the temperature rise ΔT of the high heat capacity material during the thermal runaway of the single cell is less than or equal to 100 °C. The fact that the ΔT is not too high can ensure more accurate test results of the above Q. Specifically, the ΔT ≤ 95 °C, ≤ 90 °C, ≤ 80 °C, ≤ 70 °C, ≤ 60 °C, ≤ 50 °C, ≤ 40 °C, ≤ 30 °C, etc. In some embodiments, the ΔT can be in the range of 20-30 °C.

[0038] In the embodiments of the present application, the wall thickness of the heat-conducting container 30 is between 0.05 mm and 5 mm. This can ensure that the heat-conducting container 30 has appropriate mechanical properties and will not affect its rapid transfer of heat generated from the thermally runaway battery to the high heat capacity material placed therein due to excessive thickness, so as to quickly measure the above Q.

[0039] In the present application, the heat-conducting container 30 is made of a material with high thermal conductivity. Among them, the side wall of the heat-conducting container 30 that fits the single battery 100 can withstand a temperature of more than 500 °C. Exemplarily, the side wall of the heat-conducting container 30 or the entire heat-conducting container 30 can be made of a metal material with good thermal conductivity (such as steel plate, aluminum plate, etc.), or a high-temperature-resistant inorganic non-metallic material, or an inorganic-organic composite material, etc.

[0040] In the present application, the heat-insulating container 200 can be made of a material with low thermal conductivity, and can specifically be surrounded by a plate with low thermal conductivity. Among them, the thermal conductivity of the material with low thermal conductivity is lower than 0.2 W / (m·K). In some embodiments of the present application, the heat-insulating container 200 is surrounded by aluminum silicate plates.

[0041] In the embodiments of the present application, refer to Figure 4 , the heat-absorbing member 20 may include a heat-absorbing main material 21 and a packaging film 22. Among them, a receiving cavity 221 is formed inside the packaging film 22, and the heat-absorbing main material 21 is disposed in the receiving cavity 221. The presence of the packaging film 22 can improve the wrapping and protection of the heat-absorbing main material 21, and can prevent the leakage and shedding of the active ingredients in the heat-absorbing main material 21, etc. Among them, the packaging film 22 can be selected from one or more of PP (polypropylene), PET (polyethylene terephthalate), PI (polyimide), TPU (thermoplastic polyurethane elastomer), aluminum-plastic film, etc. These materials have a certain flexibility, which can make the packaging film 22 closely adhere to the surface of the heat-absorbing main material 21 and play a good protection role. In some embodiments, the packaging film 22 may be rectangular, and its two side edges or the four sides can be sealed by heat sealing. In addition, the thickness of the packaging film 22 can be designed according to actual needs. In one embodiment, the mass of the packaging film 22 can be very light, and the mass difference between the heat-absorbing main material 21 and the heat-absorbing member 20 is not large. The mass of the heat-absorbing main material 21 can be regarded as the mass of the heat-absorbing member 20. In another embodiment, the mass of the packaging film 22 may be close to or exceed the mass of the heat-absorbing main material. In this case, only the mass of the heat-absorbing main material is calculated. Further, when the mass of the packaging film 22 is less than 10% of the mass of the heat-absorbing main material, for the convenience of measurement, the mass of the heat-absorbing member can be regarded as the mass of the heat-absorbing main material.

[0042] In some embodiments of the present application, refer to Figure 5The heat absorbing main material 21 includes a frame 210 and a heat absorbing material 212. The frame 210 has a plurality of holes 211 penetrating the frame along the thickness direction of the frame, and the heat absorbing material 212 is filled in the holes 211. In this case, the heat absorbing material 212 is an 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 the skeleton 210 can be made of a mesh polymer material.

[0043] In the present application, 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, and ethylene glycol. In some embodiments of the present application, 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 adjusted 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 a liquid phase change medium. In some other embodiments of the present application, the heat-absorbing material 212 can be a material that retains liquids such as ethanol and ethylene glycol.

[0044] In some other embodiments of the present application, the main endothermic material 21 does not include a skeleton, and the main endothermic material 21 may be only the above-mentioned endothermic material. The above-mentioned endothermic material may be directly encapsulated in the encapsulation film 22. Exemplarily, the main endothermic material may be the above-mentioned hydrogel, hydrated salt or a composite thereof.

[0045] In one embodiment of the present application, no matter 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 to reduce the quality of the endothermic material, so as to ensure the heat absorption effect of the endothermic material.

[0046] In the embodiment of the present application, the phase change temperature of the above-mentioned endothermic main material 21 can be in the range of 85°C-180°C. To be precise, the phase change temperature of the above-mentioned endothermic 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, and the phase change temperature of the endothermic main material is also controlled 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.

[0047] In an embodiment of the present application, the ratio of the area of the surface 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. By setting the ratio of the contact area between the heat absorber and the first surface within this range, it can be ensured that the heat absorber 20 is in full contact with the first surface 10a to ensure a good heat absorption effect of the heat absorber 20. Preferably, the area of the surface of the heat absorber in contact with the first surface is equal to the area of the first surface, so that the heat absorber can completely absorb the heat transferred from the first surface of a single battery adjacent to the heat absorber.

[0048] In an embodiment of the present application, 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. Through the above setting, it can be ensured that the heat absorber 20 does not deviate too much from the first surface 10a to improve the heat absorption effect of the heat absorber.

[0049] In the embodiment of the present application, the above battery assembly 300 may be a battery module or a battery pack. Among them, in the above battery assembly 300, multiple single batteries 100 may form a battery pack through series connection, parallel connection or a combination thereof. Multiple single batteries 100 may also be encapsulated together by the same outer shell frame and communicate with the outside through a unified boundary.

[0050] The embodiment of the present application also provides a device, which includes the above battery assembly of the embodiment of the present application. Among them, the device may include an electrical equipment or an energy storage system, etc.

[0051] Among them, the electrical equipment includes but is not limited to a transportation vehicle (such as a ship, a vehicle (such as a new energy vehicle, a bus), etc.) or a 3C product (such as a mobile phone, a tablet computer), etc. Among them, the new energy vehicle may be a pure electric vehicle, a hybrid vehicle or an extended-range electric vehicle, etc.

[0052] Among them, the energy storage system may be a site energy backup power system, an intelligent photovoltaic energy storage power station, etc.

[0053] The technical solution of the present application will be further described below in conjunction with multiple specific embodiments.

[0054] Embodiment 1

[0055] A square single battery, the size of its shell is: the length a' is 475 mm, the height b' is 83.8 mm, the width c' is 14.5 mm, the cell type is ternary NCM811, and the battery mass is 1.3 kg; the full charge capacity I and the average discharge voltage U of the single battery are shown in Table 1.

[0056] Select the phase change latent heat H pA hydrogel with a heat absorption capacity of 1600 kJ / kg and a phase change temperature of 118 °C is used as the heat absorption material. It is coated on the PET substrate and cured to form a film with a certain thickness. 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). An aluminum-plastic film (with a thickness of 0.085 mm) is used to thermally seal the heat absorption main material to obtain a sheet-shaped heat absorption component (which can be called a "heat absorption sheet").

[0057] A plurality of the above monomer cells are assembled into a battery module, and the above heat absorption sheet is placed between the large surfaces of any two adjacent monomer cells arranged opposite to each other. That is, in this battery module, the arrangement pattern of the monomer cells and the heat absorption sheets is ABAB…, where A represents the monomer cell and B represents the heat absorption sheet.

[0058] Among them, the heat runaway heat of the above monomer cell is tested by heat balance calorimetry to obtain the Q value in the foregoing relational expression. Specifically, it includes the following steps:

[0059] 1) Provide two heat conduction containers 30 filled with a high heat capacity material (specifically water, and its specific heat capacity c2 is specifically 4.2 kJ / (kg·K)); among them, the heat conduction containers are made of aluminum plates, and the wall thickness is about 2 - 3 mm; in each heat conduction container, the volume occupied by the high heat capacity material is about 80% of the available volume in the heat conduction container. Weigh the total mass M of the high heat capacity material contained in one heat conduction container, and the unit is kg.

[0060] 2) As shown in Figure 3 , place one of the above monomer cells with 100% SOC at room temperature (which can be separated from the battery module) and two heat conduction containers 30 filled with a high heat capacity material in the heat insulation container 200, and make the two large surfaces of the monomer cell fit against the side walls of the two heat conduction containers; arrange two relatively arranged thermocouples in one of the heat conduction containers for temperature acquisition, one adjacent to the side wall that fits against the large surface of the monomer cell, and the other far from the large surface of the monomer cell. Before the monomer cell undergoes thermal runaway, collect the temperatures T1 of the two thermocouples, and this temperature is also the initial temperature of the high heat capacity material.

[0061] 3) Then trigger the thermal runaway of the monomer cell by means of acupuncture, and collect the temperature T2 when the temperatures of the two thermocouples reach consistency, and obtain the temperature rise ΔT of the high heat capacity material during the thermal runaway of the monomer cell, ΔT = T2 - T1; furthermore, calculate the heat Q transferred by the monomer cell through one large surface during the thermal runaway, Q = M × c2 × ΔT.

[0062] According to the description in the foregoing of this application, the upper limit value and the lower limit value of the mass of the heat absorption main material can be calculated (when substituting into the foregoing relational expression, α is taken as 1.2), and the results are shown in Table 1. After comparison, it is found that the actual mass m of the above heat absorption main material is between the upper limit value and the lower limit value.

[0063] In addition, when measuring the above battery assembly, the ratio of the sum of the thicknesses c of all the heat-absorbing sheets to the sum of the widths c' (i.e., their thicknesses) of the single cells was measured, and the results are shown in Table 1. The battery assembly was also subjected to a pinprick test, which specifically included the following steps: after each single cell was fully charged, a steel needle with a diameter of 3 mm was used to prick the middle position of the middle single cell at a speed of 0.5 mm / s until thermal runaway of the battery occurred and then stopped, and continuous observation was carried out until the collected temperature was less than 100 °C to end. After the experiment, it was recorded whether the adjacent cells experienced thermal runaway (the thermal runaway criterion was a voltage drop or the opening of the explosion-proof valve), that is, whether thermal diffusion occurred.

[0064] According to Example 1, battery assemblies of other examples and comparative examples were prepared, and the main differences are listed in the following tables.

[0065] Among them, for Example 7, the H p of the heat-absorbing material used was 1756.5 kJ / kg. The water content of this heat-absorbing material was different from that of Example 1, and when substituting it into the foregoing relational expression, α was taken as 1.15; for Example 8, the H p of the heat-absorbing material used was 846.15 kJ / kg. Its water content was different from that of Example 1, and when substituting it into the foregoing relational expression, α was taken as 1.1.

[0066] Table 1

[0067]

[0068] Table 2

[0069]

[0070]

[0071] Table 3

[0072]

[0073] This application also sets the following Comparative Example 6.

[0074] The difference between Comparative Example 6 and Comparative Example 5 is only that: the H p of the heat-absorbing material used is 461 kJ / kg.

[0075] In Comparative Example 6, the H p value is not within the range of H pWithin the range. For the time being, α = 1.3 can be substituted into the foregoing relational expression of the present application to calculate that the lower limit of the mass of the main heat-absorbing material is 152.95 g and the upper limit of the mass is 458.85 g. The actual mass m of the main heat-absorbing material in Comparative Example 6 is 92.95 g, which is not between the upper limit value and the lower limit value. Through the needle-punching experiment, it is found that in the battery module of Comparative Example 6, the heat of the thermally out-of-control battery will spread.

[0076] As can be learned from the above tables, in the battery module, when the mass of the heat-absorbing sheet disposed between adjacent single cells satisfies the relational expression required by the present application, the heat-absorbing sheet can preferably inhibit the heat diffusion of the thermally out-of-control single cell to the adjacent cells, and the total thickness of all the heat-absorbing sheets in the battery module accounts for a relatively low proportion. 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 value of the foregoing relational expression of the present application, and it cannot inhibit the heat diffusion of the thermally out-of-control battery in the battery module; the mass of the heat-absorbing sheet in Comparative Example 2 is greater than the upper limit value of the foregoing relational expression of the present application. Although there is no heat diffusion of the thermally out-of-control battery in the battery module, the total thickness of the heat-absorbing sheets in the battery module accounts for a relatively large proportion, affecting its grouping efficiency. In addition, the comparisons between Comparative Example 3 and Example 4, between Comparative Example 4 and Example 7, and between Comparative Example 5 and Example 8 also have similar phenomena. In Comparative Example 6, the H p value is too low and the heat absorption capacity is weak, and it cannot effectively inhibit the heat diffusion of the thermally out-of-control battery.

[0077] In addition, the data of Examples 1-3 show that for battery modules using different types of single cells, when the mass of the heat-absorbing sheet used satisfies the foregoing relationship defined by the present application, the thermal runaway of the battery core can also be inhibited, and its volume accounts for a relatively low proportion. The data of Examples 3-5 show that when the sorting methods of the single cells and the heat-absorbing sheets are different, when the mass of the heat-absorbing sheet is controlled to satisfy the foregoing relationship defined by the present application, the thermal runaway of the battery core can also be inhibited, and its volume accounts for a relatively low proportion; the comparison between Example 3 and Example 6 shows that for battery modules using single cells of different sizes and different capacities, when the mass of the heat-absorbing sheet is controlled to satisfy the foregoing relationship defined by the present application, the thermal runaway of the battery core can also be effectively inhibited, and the volume of the heat-absorbing sheet accounts for a relatively low proportion.

[0078] The above-described embodiments only represent several implementation manners of the present application, and their descriptions are relatively specific and detailed, but should not be construed as limiting the patent scope of the present application. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several deformations and improvements can still be made, and these all belong to the protection scope of the present application.

Claims

1. A battery assembly, characterized in that, It includes a plurality of single cells, and a heat absorber is disposed between at least some of the first surfaces of the adjacent single cells that are oppositely arranged; wherein, the heat absorber includes a main heat-absorbing material, the main heat-absorbing material includes a heat-absorbing material, and the latent heat of phase change H of the heat-absorbing material p is greater than or equal to 500 kJ / kg; wherein, the mass m of the main heat-absorbing material 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 by one of the single cells adjacent to the heat absorber 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 according to claim 1, characterized in that, The ratio of the surface area of the heat absorber in contact with the first surface to the area of the first surface is greater than or equal to 0.8 and less than or equal to 1.

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

4. The battery assembly according to any one of claims 1-3, characterized in that, The heat absorber further includes a packaging film, and a receiving cavity is formed inside the packaging film, and the main heat absorption material is disposed in the receiving cavity.

5. The battery assembly according to any one of claims 1-4, characterized in that, The main heat absorption material includes a skeleton and the heat absorption material. The skeleton has a plurality of holes penetrating the skeleton in the thickness direction of the skeleton, and the heat absorption material fills the holes.

6. The battery assembly according to any one of claims 1-4, characterized in that, The main heat absorption material is the heat absorption material.

7. The battery assembly according to any one of claims 1-6, characterized in that, The heat absorption material is a composite material retaining a liquid phase change medium.

8. The battery assembly according to claim 7, characterized in that, The heat absorption material is a hydrogel, hydrated salt or a composite thereof retaining water.

9. The battery assembly according to any one of claims 1-8, characterized in that, A heat absorber is provided between any two adjacent monomer cells.

10. The battery assembly according to any one of claims 1-9, characterized in that, The monomer cell has a square housing; the first surface is the large surface of the square housing.

11. The battery assembly according to any one of claims 1 to 10, characterized in that, The phase change temperature of the heat absorption material is in the range of 85 °C - 180 °C.

12. A device, characterized in that, Including the battery assembly according to any one of claims 1-11, wherein the device includes an electrical equipment or an energy storage system.

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