Battery assembly, electric device, and energy storage system

Abstract

A battery assembly (1), an electric device (30), and an energy storage system (40). The battery assembly (1) comprises a plurality of cells (10) arranged in a first direction; a heat absorption member (20) is provided between at least some of two adjacent cells (10); each heat absorption member (20) comprises a packaging member (21), and a framework (22) and a heat absorption material (23) which are accommodated in the packaging member (21); and the battery assembly (1) satisfies formulas (I) and (II), wherein A is the area of the orthographic projection of the heat absorption members (20) in the first direction, the unit is m2, λ is a compressive strain resistance coefficient of the heat absorption materials (23), ζ is an expansion force reduction coefficient of the packaging members (21), E1 is an elastic modulus of the material of the frameworks (22) at room temperature, E2 is an elastic modulus of the heat absorption materials (23) at room temperature, the unit is MPa, Fmax is a maximum expansion force of the cells (10) in a thermal runaway process, and the unit is MN. The battery assembly (1) satisfies the formulas above, so that the heat absorption members (20) have excellent heat absorption effect and strong deformation resistance, thereby effectively improving the thermal safety performance of the battery assembly (1).

Description

Battery assembly, electric device and energy storage system

[0001] This application claims priority to the Chinese patent application No. 202410874990.5, filed on June 28, 2024, and entitled "Battery assembly, electric device and energy storage system", the content of which is incorporated herein by reference in its entirety. TECHNICAL FIELD

[0002] The present application relates to the technical field of batteries, and more particularly, to a battery assembly, an electric device and an energy storage system. BACKGROUND

[0003] With the increasing application of secondary batteries, especially in electric devices and energy storage systems with high energy consumption demand. The above-mentioned electric devices or energy storage systems generally carry a battery assembly including a plurality of single batteries. Once thermal runaway occurs in a certain single battery under extreme working conditions, heat is easily spread in the battery assembly, causing thermal runaway of the battery assembly and resulting in safety accidents.

[0004] In order to inhibit the spread of heat in the battery assembly during the above-mentioned thermal runaway process, the industry often sets up heat-absorbing materials between adjacent single batteries. However, the single batteries will also swell and press the heat-absorbing materials during the thermal runaway process, causing the heat-absorbing materials to deform or even overflow, which seriously affects the heat-absorbing effect. Therefore, it is urgent to provide a new battery assembly design scheme for inhibiting heat diffusion. SUMMARY

[0005] An embodiment of the present application aims to provide a battery assembly, an electric device and an energy storage system. The heat-absorbing member in the battery assembly can have both better heat-absorbing effect and stronger deformation resistance, which can effectively improve the thermal safety performance of the battery assembly.

[0006] In a first aspect, the present application provides a battery assembly, comprising a plurality of single batteries arranged along a first direction, at least part of two adjacent single batteries being provided with a heat-absorbing member; the heat-absorbing member comprises an encapsulating member and a skeleton and a heat-absorbing material accommodated in the encapsulating member; the battery assembly satisfies:

[0007] and,

[0008] Wherein, A is the orthogonal projection area of the heat-absorbing member in the first direction, with the unit of m 2 ; λ is the compression strain coefficient of the heat-absorbing material; ζ is the expansion force reduction coefficient of the encapsulating member; E1 and E2 are the elastic modulus of the material of the skeleton and the heat-absorbing material at room temperature, respectively, with the unit of MPa; Fmax is the maximum expansion force of the single battery during the thermal runaway process, with the unit of MN.

[0009] When the heat absorption member arranged at least partially between adjacent single batteries in the battery assembly satisfies the above relationship, when one or more single batteries in the battery assembly undergo thermal runaway under extreme working conditions (e.g., needle puncture, strong impact), the heat absorption member can effectively inhibit the large-area spread of heat in the battery assembly, sufficiently reduce the risk of explosion and other safety accidents of the entire battery assembly, and protect the personal safety and property safety of consumers. In addition, when the heat absorption member satisfies the above relationship, higher mechanical properties can be achieved under the same amount, while effectively avoiding the failure of protection caused by the leakage of the heat absorption material due to the rupture of the heat absorption member, sufficiently reducing the space ratio of the heat absorption member in the battery assembly, improving the benefit ratio of the heat absorption member, saving materials, and having strong market competitiveness.

[0010] In some embodiments, 1 MPa≤E1≤105MPa.

[0011] In some embodiments, 0.1 MPa≤E2≤1 MPa.

[0012] In some embodiments, 0.8≤ζ≤1.

[0013] In some embodiments, 0.01≤λ<0.6, preferably 0.05≤λ≤0.2.

[0014] In some embodiments, 0.01 MN≤Fmax≤0.5 MN.

[0015] In some embodiments, 0.01 m 2 ≤A≤0.2 m 2 .

[0016] In some embodiments, 0.5%≤V1≤50%, preferably 5%≤V1≤35%; wherein V1 is the volume percentage of the volume of the skeleton at room temperature to the total volume of the skeleton and the heat absorption material.

[0017] In some embodiments, the skeleton comprises a plurality of pores filled with the heat absorption material.

[0018] In some embodiments, the heat absorption member is arranged between any two adjacent single batteries.

[0019] In some embodiments, the single battery is a square single battery, and the heat absorption member is arranged close to the large face of the single battery.

[0020] In a second aspect, the application further provides a power consuming device comprising the battery assembly provided in the first aspect of the application. The power consuming device has strong market competitiveness since the battery assembly provided in the first aspect of the application is used to supply power for the power consuming device.

[0021] In some embodiments, the power consuming device further comprises a housing, and the battery assembly is arranged in the housing, and the heat absorption member is arranged between the monomer battery and the housing along the first direction.

[0022] In a third aspect, the application further provides an energy storage system comprising the battery assembly provided in the first aspect of the application. The energy storage system has good thermal safety performance and strong market competitiveness since the battery assembly provided in the first aspect of the application is used. BRIEF DESCRIPTION OF DRAWINGS

[0023] FIG. 1 is a schematic structural diagram of a cross section of a battery assembly according to an embodiment of the application;

[0024] FIG. 2A is a schematic structural diagram of a cross section of a heat absorption member according to an embodiment of the application;

[0025] FIG. 2B is a schematic structural diagram of a cross section of a heat absorption member according to another embodiment of the application;

[0026] FIG. 3 is a schematic structural diagram of a test assembly for a heat diffusion test according to an embodiment of the application;

[0027] FIG. 4 is a schematic diagram of a power consuming device according to an embodiment of the application;

[0028] FIG. 5 is a schematic diagram of an energy storage system according to an embodiment of the application. DETAILED DESCRIPTION

[0029] The specific embodiments of the application are described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are merely intended to illustrate and explain the application, and are not intended to limit the application.

[0030] In the present application, the orientation words such as "upper", "lower" and the like are generally defined with the drawing surface direction of the corresponding drawing, only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the indicated device or element must have a particular orientation, and a particular orientation configuration and operation, and therefore cannot be understood as a limitation on the present application. "Inner", "outer" refers to the inner and outer of the corresponding component contour. The purpose of using the terms "first", "second" and the like is to distinguish different components, and does not have sequentiality and importance. Among them, the X direction shown in Figure 1 can be the first direction, the Y direction can be the second direction, and the Z direction can be the insertion direction of the first connecting structure 2 and the second connecting structure 3. In addition, in the following description, when referring to the drawings, the same reference numerals in different drawings represent the same or similar elements, unless otherwise explained.

[0031] In the description of the present application, it should also be noted that, unless otherwise explicitly specified and limited, the terms "arrangement", "connection", "connection", "installation" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be directly connected, or indirectly connected through an intermediate medium. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0032] The technical scheme of the present application will be further described below in conjunction with the drawings.

[0033] Please refer to Figure 1 and Figure 2A, the present application embodiment provides a battery assembly 1, comprising a plurality of single batteries 10 arranged along a first direction, at least part of the two adjacent single batteries 10 is provided with a heat absorption member 20; the heat absorption member 20 comprises an encapsulating member 21 and a skeleton 22 and a heat absorption material 23 accommodated in the encapsulating member 21; the battery assembly 1 satisfies:

[0034] and,

[0035] Wherein, A is the orthogonal projection area of the heat absorption member 20 in the first direction, unit is m 2 ; Lambda is the compression strain coefficient of the heat absorption material 23; Zeta is the expansion force reduction coefficient of the encapsulating member 21; E1, E2 are the elastic modulus of the material of the skeleton 22 and the heat absorption material 23 at normal temperature, respectively, unit is MPa (megapascal); Fmax is the maximum expansion force of the single battery 10 in the thermal runaway process, unit is MN (megapascal). In the present application embodiment, the normal temperature is 25±2℃.

[0036] In the embodiments of the present application, FIG. 1 and FIG. 2A are exemplary drawings, and the number of single batteries, the number of heat absorption members, and the arrangement and size of the two in the drawings do not limit the present application; the thickness of the packaging member and the shape and size of the framework in FIG. 2A also do not limit the embodiments of the present application.

[0037] In the embodiments of the present application, the first direction is the arrangement direction of the plurality of single batteries; A is the area of the orthographic projection of the heat absorption member in the first direction. It can be understood that, in some embodiments, in order to improve the heat absorption effect, the heat absorption member is in direct contact with the single battery. The surface of the heat absorption member in contact with the single battery is generally a plane, and the surface of the single battery in contact with the heat absorption member is also generally a plane. For the convenience of description, an adjacent single battery and a heat absorption member are taken as an example, and the surface opposite to the single battery and the heat absorption member is defined as a first surface, and the surface opposite to the single battery and the heat absorption member is defined as a second surface, both the first surface and the second surface are planes, which are described as follows: when the first surface and the second surface completely coincide, the above-mentioned A is equal to the area of the first surface, and also equal to the area of the second surface; in other cases, the above-mentioned A takes the area of the second surface. Wherein A can be obtained by measuring the size of the first surface according to the shape of the first surface, and calculating the area of the first surface. In some specific embodiments, along the first direction, the orthographic projection of the heat absorption member on the single battery overlaps with the single battery, so the first surface of the heat absorption member can be determined by measuring the surface area of the single battery on the side facing the heat absorption member.

[0038] In the embodiments of the present application, the "thermal runaway" of the single battery refers to the rapid change of the temperature rise rate of the single battery caused by the heat release chain reaction of the single battery, which is specifically manifested as that the temperature rise rate of the single battery is ≥1 ℃ / s in the needle test. In the embodiments of the present application, the needle test of the single battery includes: setting a thermocouple on the surface of the single battery for testing and monitoring the temperature change thereof, baking the single battery in a full state (100% SOC) to 45℃ in a thermostat, then placing the single battery in a clamp, setting aluminum plates with a thickness of 2mm on the opposite ends of the single battery in the thickness direction perpendicular to the single battery (for example, for a square battery, the thickness direction of the single battery is perpendicular to the largest surface of the square battery), and setting heat-conducting glue with a thickness of 1mm between the single battery and the aluminum plates; setting calcium silicate plates with a thickness of 36mm on the opposite surfaces of the single battery in the first direction and setting calcium silicate plates with a thickness of 28mm on the other surfaces, and setting a mechanical sensor on each of the above surfaces; preparing a one-word needle with a diameter of 4.5mm, and piercing the single battery from the center position of the surface of the single battery perpendicular to the first direction to the single battery at a speed of 1mm / s until the thermal runaway occurs, monitoring the temperature change and the mechanical sensor data of the single battery in the whole process from before the needle test to when the temperature of the single battery drops to the stable temperature (the temperature corresponding to the time when the temperature of the single battery no longer changes with time), recording the critical temperature before the thermal runaway of the single battery in this process as the thermal runaway temperature (i.e. the temperature of the single battery at the moment when the temperature rise rate of the single battery is ≥1 ℃ / s, or determining the turning point of the temperature rise curve of the single battery based on the temperature of the single battery (the turning point is the moment when the temperature rise rate is ≥1 ℃ / s), and the temperature corresponding to the turning point is the thermal runaway temperature of the single battery), and the maximum reading of the mechanical sensor is Fmax.

[0039] According to the thermal runaway temperature of the single battery measured by the above needle test, the elastic moduli E1 and E2 of the framework and the heat-absorbing material at the above thermal runaway temperature are determined according to GB / T 22315-2008. When the framework is a non-metallic framework, the elastic moduli E1 and E2 of the framework and the heat-absorbing material can also be determined according to the scheme for determining the elastic modulus of GB / T 22315-2008. The thermal runaway temperature is the critical temperature before the thermal runaway of the single battery in the above single battery needle test scheme.

[0040] It can be understood that, generally, the plurality of single batteries in a single battery assembly are the same. At this time, for the battery assembly, any single battery in the battery assembly can be randomly selected for the above thermal runaway test. If in some special cases, the plurality of single batteries in a single battery assembly are not completely consistent, the thermal runaway temperature and the maximum expansion force Fmax of different single batteries need to be tested respectively, and the parameters of the heat absorption member need to be selected according to the parameters of the single battery adjacent thereto, when the parameters of the two single batteries arranged on the opposite two side surfaces of the heat absorption member along the first direction are different, the parameters of the heat absorption member and the two single batteries need to satisfy the quantity relationship defined in the embodiments of the present application respectively. In some specific embodiments of the present application, the plurality of single batteries in the battery assembly are the same. It should be noted that the plurality of single batteries are the same, which means that the plurality of single batteries are the same in composition and have the same size and appearance.

[0041] In the embodiments of the present application, the test of the expansion force reduction coefficient ζ of the packaging member includes: the compression stress-strain curves of the heat absorption member and the heat absorption member sample without the packaging member can be measured at room temperature (25±5°C) using a universal testing machine. Specifically, the sample size is recommended to be 50x50mm, the thickness can be arbitrarily selected, generally recommended to be 1-5mm, the entry force is 5N, the compression rate is 2mm / min, the compression is to 1MPa, and the strain of the heat absorption member and the heat absorption member sample without the packaging member at this time (i.e. the time when the compression is to 1MPa) is recorded, respectively, δ1, δ2, ζ=(δ2-δ1).

[0042] In some embodiments of the present application, 0.01≤λ<0.6; that is, the compressive strain coefficient of the heat absorption material is 0.01-0.6. Controlling the compressive coefficient of the heat absorption member within the above range is easy to obtain in industry, and can make the heat absorption member have higher compressive resistance, so that the risk of the packaging member of the heat absorption member being broken to cause the heat absorption material to leak during the expansion of the thermal runaway of the single battery is smaller, that is, the risk of thermal spread of the battery assembly is further reduced. In the embodiments of the present application, the test of the compressive strain coefficient λ of the heat absorption material includes: measuring the compressive stress-strain curve of the pure heat absorption material at room temperature (25±5°C) using a universal testing machine. The size of the sample is recommended to be 50×50 mm, the thickness can be arbitrarily selected, generally recommended to be 1-5 mm, the entry force is 5 N, the compression rate is 2 mm / min, and the sample is compressed to the material rupture deformation (material rupture), and the strain (or compression deformation ratio) corresponding to the time (i.e. the time when the material is compressed to the material rupture deformation) under the compressive stress-strain curve obtained above is recorded as λmax, and λ is less than λmax. The test must be tested at least 5 times with different samples. In some specific embodiments, 0.1λmax≤λ≤0.4λmax. In some specific embodiments, 0.05≤λ≤0.2. Specifically, the compressive strain coefficient λ of the heat absorption member may, for example, be 0.01, 0.03, 0.05, 0.08, 0.1, 0.2, 0.3, 0.4, 0.5, 0.55, 0.59, etc.

[0043] In the embodiments of the present application, the heat absorption material in the heat absorption member is used to absorb the heat generated by the single battery during thermal runaway, so as to inhibit the spread of heat in the battery assembly; the skeleton is used to provide mechanical strength for the heat absorption member, so as to reduce the risk of deformation and rupture of the heat absorption member after being extruded. In the embodiments of the present application, the skeleton and the heat absorption material are sealed in the accommodation space formed by the packaging member.

[0044] Although the related art has added a mechanical reinforcing body to the heat absorption material to form a heat absorption piece to enhance structural stability, the applicant found that in the actual production and application process, the material properties of the mechanical reinforcing body, the mechanical properties of the heat absorption material itself, the changing properties of different single batteries in the thermal runaway process, and even the mechanical properties of the packaging piece will significantly affect the effect of the heat absorption piece, that is, significantly affect the performance of the structural stability of the heat absorption piece in the thermal runaway process, and then affect the inhibition effect of the heat absorption piece on the heat diffusion in the battery assembly, thereby changing the safety performance of the battery assembly. The applicant found through theoretical derivation and experimental verification that the elastic modulus E1 of the material of the skeleton in the heat absorption piece, the elastic modulus E2 of the heat absorption material, and the expansion force reduction coefficient ζ of the packaging piece will significantly affect the mechanical properties of the heat absorption piece and thus affect its effect on inhibiting heat diffusion; further, when the above parameters are determined, their matching relationship will also affect the strain properties of the heat absorption piece, and then affect the final deformation amount of the heat absorption piece, and affect the inhibition of heat diffusion in the battery assembly, so the applicant introduces the strain coefficient λ of the heat absorption piece to correct the deformation amount of the heat absorption piece in the thermal runaway process; in addition, the orthogonal projection area A of the heat absorption piece in the first direction will also affect the spread of heat in the battery assembly.

[0045] The above-mentioned multiple influencing factors cooperate and counteract each other, and the applicant found that when the above-mentioned influencing factors satisfy a specific mathematical relationship, it is more beneficial to the thermal safety performance of the battery assembly, and the manufacturing cost and space ratio of the heat absorption piece can be controlled in a lower range.

[0046] Specifically, the battery assembly needs to satisfy:

[0047] And,

[0048] When the heat absorption piece arranged at least partially between adjacent single batteries in the battery assembly satisfies the above relationship, when one or more single batteries in the battery assembly occur thermal runaway under extreme working conditions (for example, needle puncture, strong impact), the heat absorption piece can effectively inhibit the large-area diffusion of heat in the battery assembly, sufficiently reduce the risk of explosion and other safety accidents of the entire battery assembly, and protect the personal safety and property safety of consumers. In addition, when the heat absorption piece satisfies the above relationship, not only can a higher deformation resistance be achieved under the same amount, but also the risk of protection failure caused by leakage of the heat absorption material due to the rupture of the heat absorption piece can be effectively avoided, while the space ratio of the heat absorption piece in the battery assembly is sufficiently reduced, the profitability of the heat absorption piece is improved, the material is saved, and the market competitiveness is strong.

[0049] In the embodiments of the present application, if the value of E1+E2 is too small, it is very likely that an excessive amount of skeleton material is needed to ensure the strength of the heat absorption member, which is very unfavorable for the heat absorption effect of the heat absorption member, thereby affecting the inhibition of heat diffusion; if the value of (E1+199E2) / 100 cannot meet the above formula, the mechanical strength of the heat absorption member will not be enough, and the heat absorption member is prone to deformation and rupture after thermal runaway of the single battery cell.

[0050] In the embodiments of the present application, the system, model, shape and size of the single battery are not limited. The formula provided in the embodiments of the present application is applicable to a battery assembly composed of single batteries of any system, any model, any shape and any size. For example, the single battery can include but is not limited to a lithium battery, a sodium battery, a potassium battery, a zinc battery, etc. The shape of the single battery can be square, or can be a blade-shaped battery, a hexagonal prism-shaped battery or a special-shaped battery, etc.

[0051] In some embodiments of the present application, 0.5%≤V1≤50%, wherein V1 is the volume percentage of the volume of the skeleton at room temperature to the total volume of the skeleton and the heat absorption material. Specifically, the volume percentage V1 of the skeleton at room temperature (25°C±5°C) can be but is not limited to 0.5%, 1%, 2%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, based on the total volume of the heat absorption material and the skeleton. When the volume percentage V1 of the skeleton at room temperature is controlled within the above range, V1 can be close to the upper limit of the above range when the heat generation of the single battery cell is small; when the heat generation of the single battery cell is large, the value of V1 can be adjusted smaller. In order to control the heat absorption effect of the heat absorption member to be more optimal, in some embodiments, the heat content value of the heat absorption member is ≥1000 J / (g·℃); and based on the fact that the heat content of the heat absorption member mainly depends on the latent heat of the heat absorption material and the proportion of the heat absorption material in the heat absorption member, in some specific embodiments, 5%≤V1≤35%. In this way, it is beneficial to balance the strength and heat absorption effect of the heat absorption member.

[0052] In some embodiments of the present application, the preparation of the battery assembly comprises:

[0053] S01, confirming the maximum expansion force Fmax of the single battery to be used in the thermal runaway process, measuring the area of the large face of the single battery to determine A, and specifying the size of the heat absorption member, at this time the thickness size of the heat absorption member can also be determined according to actual needs;

[0054] S02, determining the compression resistance coefficient λ of the heat absorption member and the expansion force reduction coefficient ζ of the packaging member, and determining E1 and E2 according to the formula (1) defined in the embodiments of the present application;

[0055] S03, selecting the material of the skeleton, the heat absorption material and the material of the packaging member according to the above parameter range, and testing the specific E1 and E2;

[0056] S04, determining the size of the hole of the skeleton;

[0057] S05, preparing the heat absorption member;

[0058] S06, preparing the battery assembly.

[0059] For step S05, the following is a simple description of a specific embodiment: as shown in FIG. 2B, for the skeleton of a quadrilateral mesh, the width of a single beam in the skeleton is denoted as h, a is the length of the heat absorption member, b is the width of the heat absorption member, Cx and Cy are the long side size and the short side size of the hole respectively, Sx is the number of beams of the skeleton in the x direction, and Sy is the number of beams of the skeleton in the y direction. The area of the orthographic projection of the heat absorption member in the first direction is A, and the area of the orthographic projection of the skeleton material in the first direction is AV1, so AV1 = hbSy + haSx - SxSyh2, Sx = (b / (h+Cx)), Sy = (a / (h+Cx)), and thus the size Cx and Cy of the hole of the skeleton can be calculated. In the embodiment of the present application, the values of h, Cx and Cy are not limited, and those skilled in the art can determine them according to actual production needs. In the embodiment of the present application, the cross-sectional shape of the hole is also not limited; specifically, the cross-sectional shape of the hole can be square, circular, elliptical, triangular, pentagonal, hexagonal, irregular, etc. When the cross-sectional shape of the hole is circular, both the short side size and the long side size are the diameter.

[0060] In some embodiments of the present application, any two adjacent single batteries in the battery assembly can be separated by a heat absorption member. The single batteries and the heat absorption members are arranged alternately in the first direction, and therefore the thickness direction of the single battery is parallel to the first direction. In this way, the heat spread between any two single batteries can be inhibited in extreme working conditions, thereby more effectively reducing the thermal safety performance of the battery assembly in extreme working conditions. The above-mentioned case is particularly suitable for a battery assembly composed of single batteries with poor safety performance, such as single batteries with ternary positive electrode materials. It can be understood that, in the first direction, if a single battery on the end surface of the battery assembly undergoes thermal runaway, the heat will spread in the direction of the single battery towards the end surface of the battery assembly, and the influence on the thermal safety performance of the battery assembly is relatively small. Therefore, in the first direction, near the end surface of the battery assembly, it can be a heat absorption member or a single battery. For example, the single battery is denoted as X, and the heat absorption member is denoted as Y. In the first direction, the battery assembly can include XYXY…Y, YXYX…Y, XYXYX…X, or YXYX…X.

[0061] In some other embodiments of the application, among the plurality of single batteries in the battery assembly, some of the adjacent two single batteries are provided with the heat absorption member, and the rest of the adjacent two single batteries are not provided with the heat absorption member, or the rest of the adjacent two single batteries are provided with other heat absorption materials. This case is particularly suitable for a battery assembly composed of single batteries with relatively high self-safety performance, for example, single batteries with phosphate materials as the positive active material, which can reduce the production cost. Similarly, at this time, in the first direction, it is also not limited whether the heat absorption member or other heat absorption materials are provided near the end face of the battery assembly.

[0062] It can be understood that, taking a square battery as an example, the thickness direction of the square battery is perpendicular to its large face (i.e., the side face with the largest area). When the square battery undergoes thermal runaway, it mainly expands in the thickness direction. Therefore, in some embodiments of the application, when the single battery is a square battery, the heat absorption member is provided near the large face of the single battery. In some specific embodiments, the heat absorption member is in contact with the large face of the single battery. At this time, A mentioned in the formula of the embodiments of the application can be the area of the large face of the single battery. That is, the area A of the orthogonal projection of the heat absorption member in the first direction is equal to or approximately equal to the area of the large face of the single battery. Further, the orthogonal projection of the heat absorption member in the first direction completely overlaps the large face of the single battery, or the heat absorption member covers or approximately covers the large face of the single battery. In this way, it is beneficial for the heat absorption member to fully absorb the heat emitted by the single battery during the normal charging and discharging cycle process and the thermal runaway process, and it is also more beneficial for inhibiting the spread of heat in the battery assembly, improving the thermal safety performance of the battery assembly, and also does not occupy too much internal space of the battery assembly, with high cost performance. Of course, when the single battery is a battery with other shapes, the setting position of the heat absorption member can be selected according to the thermal runaway expansion characteristics of the single battery.

[0063] In the embodiments of the application, A can be determined according to the size of the single battery. Considering the currently commonly used size of the single battery, in some embodiments of the application, 0.01m 2 ≤ A ≤ 0.2m 2 . Specifically, A can be but is not limited to 0.01m 2 , 0.05m 2 , 0.08m 2 , 0.10m 2 , 0.12m 2 , 0.15m 2 , 0.18m 2 , or 0.20m 2 .

[0064] In some embodiments of the present application, the single battery includes a shell and a cell assembly accommodated in the shell. The shell can be a shell known to those skilled in the art, for example, an aluminum plastic shell. The single battery includes a side portion, a top portion and a bottom portion, wherein the side portion connects the top portion and the bottom portion. In addition, the single battery also has a positive pole and a negative pole exposed to the top portion of the shell in a second direction, wherein the second direction is parallel to the thickness direction of the single battery. The cell assembly generally includes a plurality of positive pole pieces and a plurality of negative pole pieces, and the adjacent positive pole pieces and negative pole pieces can be separated by a separator or a semi-solid / fully solid electrolyte material. Accordingly, the single battery can be a liquid battery, or a fully solid battery or a semi-solid battery. The positive pole of the single battery can be electrically connected to the positive pole piece, and the negative pole can be electrically connected to the negative pole piece.

[0065] In the embodiments of the present application, the skeleton not only gives the heat absorption piece a higher compression resistance, but also plays a role in carrying the heat absorption material and shaping the heat absorption piece. In some embodiments of the present application, the skeleton includes a plurality of holes, and the holes are filled with heat absorption material. In some specific embodiments, the skeleton has a plurality of holes penetrating through the skeleton along the thickness direction of the skeleton (i.e., the first direction), and the holes are filled with heat absorption material. In the embodiments of the present application, the size of the heat absorption piece in the first direction is not limited; that is, the thickness of the heat absorption piece is not limited. Those skilled in the art can select according to the actual production situation; for example, the thickness of the heat absorption piece can be 1.5mm-2.5mm.

[0066] In the embodiments of the present application, the heat absorption piece can have a square, pentagonal, hexagonal, irregular image, etc. in the first direction, which can be adapted according to the shape of the single battery. In addition, the shape of the hole of the skeleton is not limited. The shape of the hole can be triangular, quadrilateral, pentagonal, hexagonal (for example, honeycomb), trapezoidal, etc. In the embodiments of the present application, the arrangement and size of the holes in the skeleton are not limited, and those skilled in the art can select according to the actual production needs, and the design structure of the skeleton commonly used in the art can be used. Even if the same skeleton arrangement is used, when the heat absorption piece satisfies the formula defined in the embodiments of the present application, a better effect of inhibiting the spread of heat in the battery assembly can be achieved.

[0067] In some embodiments of the present application, 1 MPa≤E1≤105MPa. That is, the elastic modulus of the material of the framework at the thermal runaway temperature of the single battery is 1 MPa-105MPa. In this way, the material of the framework is easy to obtain and low in cost in the industry, and the heat absorption member formed by the material is more likely to meet the aforementioned formula definition of the embodiments of the present application, and the volume ratio V1 of the framework is more likely to be controlled within a suitable range to reduce the cost. In addition, within the above range, the higher E1 is, the stronger the deformation resistance of the framework material is, and the higher E1 is, the better the deformation resistance of the heat absorption member is under the same amount and arrangement of the framework material; or in other words, when the heat absorption member has the same deformation resistance, the higher E1 is, the less the amount of the framework material is, and the volume ratio of the heat absorption material in the heat absorption member can be improved, and the heat absorption capacity per unit area of the heat absorption member can be improved. The person skilled in the art can make specific considerations according to the actual production needs and the cost of the material. Specifically, the elastic modulus of the material of the framework at the thermal runaway temperature of the single battery can be but is not limited to 1 MPa, 5 MPa, 10 MPa, 50 MPa, 100 MPa, 500 MPa, 103MPa, 5×103MPa, 104MPa, 5×104MPa, 105MPa.

[0068] In some embodiments of the present application, the material of the framework includes but is not limited to polypropylene (PP), polyethylene terephthalate (PET), glass fiber, metal, etc.

[0069] In some embodiments of the present application, 0.1 MPa≤E2≤1 MPa. That is, the elastic modulus of the heat absorption material at the thermal runaway temperature of the single battery is 0.1 MPa-1 MPa. In this way, the heat absorption material is easy to obtain in the industry, and can have a certain deformation resistance, which is beneficial to further reduce the risk of rupture of the heat absorption member due to extrusion during the thermal runaway process of the single battery. Specifically, E2 can be but is not limited to 0.1 MPa, 0.2 MPa, 0.3 MPa, 0.4 MPa, 0.5 MPa, 0.6 MPa, 0.7 MPa, 0.8 MPa, 0.9 MPa, 1.0 MPa.

[0070] In some embodiments of the present application, the heat absorption material includes but is not limited to a material containing a liquid phase change medium. In this way, the heat absorption effect can be achieved by the phase change of the liquid phase change medium, and the liquid phase change medium has a certain compression resistance. The liquid phase change medium includes at least one of water, ethanol, ethylene glycol, etc. The above composite can be a composite of hydrogel or hydrated salt and other materials (such as flame retardants), etc. Taking the hydrogel as an example, a high molecular 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.

[0071] The mechanical property of the encapsulating member also affects the compression resistance of the heat absorption member. In some embodiments of the present application, the expansion force reduction coefficient ζ of the encapsulating member is 0.8-1. In this way, the heat absorption member is easy to manufacture. In some specific embodiments, the encapsulating member is an aluminum film, and in this case, ζ is 0.8-0.9. In other specific embodiments, the encapsulating member is a PET film, and in this case, ζ is 0.9-1.0.

[0072] In the embodiments of the present application, the maximum expansion force of the single battery during the thermal runaway process depends on the parameters of the single battery, including the composition, morphology and size. Considering the various types of parameters of the single battery commonly used at present, in some embodiments of the present application, 0.01 MN≤Fmax≤0.5 MN.

[0073] In the embodiments of the present application, the battery assembly can be a battery module or a battery pack. In the above battery assembly, the plurality of single batteries can be connected in series, in parallel or in a combination thereof to form a battery pack.

[0074] When the battery assembly is a battery pack, the battery pack has a box body 11 for accommodating the single battery 10 and the heat absorption member 20. The box body 11 can include a tray, a sealing cover and the like.

[0075] The embodiments of the present application also provide a power consumption device 30 comprising the battery assembly provided by the embodiments of the present application. Since the power consumption device 30 is powered by the battery assembly provided by the embodiments of the present application, the power consumption device has strong market competitiveness.

[0076] In some specific embodiments, as shown in FIG. 4, in order to further enhance the thermal safety performance of the power consumption device 30 after the battery assembly is assembled in the power consumption device 30, the heat absorption member 20 is also arranged between the single battery 10 and the shell 31 of the power consumption device in the first direction.

[0077] In some embodiments of the present application, the power consumption device includes but is not limited to 3C electronic products such as vehicles, mobile phones, notebook computers, tablet computers and the like.

[0078] As described with reference to FIG. 5, some embodiments of the present application also provide a power storage system 40 comprising the battery assembly 1 provided by the embodiments of the present application. In some embodiments of the present application, the power storage system 40 can be a station energy backup system or a smart photovoltaic energy storage power station.

[0079] The technical solutions of the present application are further described in detail in the following embodiments.

[0080] Embodiment 1

[0081] A lithium iron phosphate battery assembly, comprising 10 lithium iron phosphate square monomer batteries with a size of 574.0*102.8*14.7 mm arranged in series along a first direction and 11 heat absorption pieces, the heat absorption pieces are respectively arranged between two adjacent monomer batteries. The maximum expansion force Fmax of the monomer battery in the thermal runaway process is 0.018 MN. In a single heat absorption piece, based on the total volume of the framework and the heat absorption material, the volume percentage of the framework at room temperature (25℃±5℃) is 48.08%. The elastic modulus E1 of the material of the framework at the thermal runaway temperature of the monomer battery is 2.7 MPa, the elastic modulus E2 of the heat absorption material at the thermal runaway temperature of the monomer battery is 0.1 MPa, the expansion force reduction coefficient ζ of the packaging piece is 0.90, and the compression strain resistance λ of the heat absorption material is 0.20. The normal projection area A of the heat absorption piece in the first direction is 0.06m 2 .

[0082] Examples 2-17

[0083] The difference from Example 1 is only that the parameters of the monomer battery and the heat absorption piece are regulated, and the specific parameters are summarized in Table 1.

[0084] Comparative Examples 1-6

[0085] The difference from Example 1 is only that the parameters of the monomer battery and the heat absorption piece are regulated, and the specific parameters are summarized in Table 1.

[0086] Table 1

[0087] Thermal diffusion test:

[0088] A high-temperature thermocouple is arranged in the above battery assembly, and is baked to 45℃ in a thermostat. Then the battery assembly is placed in a clamp as shown in Figure 3, aluminum plates with a thickness of 2mm are arranged at opposite ends of the battery assembly in the direction perpendicular to the thickness of the monomer battery, and heat-conducting glue with a thickness of 1mm is arranged between the battery assembly and the aluminum plate (not shown in Figure 3); calcium silicate plates with a thickness of 36mm are arranged on the opposite sides of the monomer battery along the first direction, and calcium silicate plates with a thickness of 28mm are arranged on the other surfaces of the monomer battery; and a mechanical sensor is arranged on each of the above surfaces; a 4.5mm diameter needle is prepared, and is vertically pierced from the center of the surface of the monomer battery perpendicular to the first direction to the middle monomer battery at a speed of 1mm / s until the thermal runaway of the monomer battery occurs, and then the thermal runaway of the adjacent monomer battery is recorded (the thermal runaway standard is that the temperature rise rate is ≥1℃ / s), that is, whether thermal diffusion occurs, and the results are recorded in Table 2.

[0089] Table 2

[0090] As can be seen from the results of Table 2, the battery assemblies provided by the embodiments of the present application do not have thermal diffusion under the needle test, and the heat absorption members do not deform and cause packaging damage, which shows that the battery assemblies provided by the embodiments of the present application have high thermal safety performance.

[0091] In addition, as can be known from Examples 1-4 and 10-13, when 0.01≤λ<0.6, the heat absorption material residue can be guaranteed while reducing the risk of deformation of the heat absorption member and extrusion of the heat absorption material from the packaging film.

[0092] The above is an exemplary embodiment of the present application, and it should be noted that those skilled in the art can make some improvements and refinements without departing from the principles of the present application, and these improvements and refinements are also considered within the protection scope of the present application.

Claims

1. A battery assembly, wherein, include: Multiple individual cells (10) are arranged along a first direction; A heat-absorbing element (20) is disposed between at least partially adjacent two said single cells (10), the heat-absorbing element (20) including an encapsulation element (21) and a skeleton (22) and a heat-absorbing material (23) housed in the encapsulation element (21); The battery assembly satisfies: and, Where A is the projected area of ​​the heat absorber (20) in the first direction, in m². 2 λ is the compressive strain coefficient of the heat-absorbing material (23); ζ is the expansion force reduction coefficient of the encapsulation component (21); E1 and E2 are the elastic moduli of the material of the skeleton (22) and the heat-absorbing material (23) at room temperature, respectively, and the units are MPa. Fmax is the maximum expansion force of the single cell (10) during thermal runaway, in units of MN.

2. The battery assembly according to claim 1, wherein, 1MPa≤E1≤105MPa.

3. The battery assembly according to claim 1 or 2, wherein, 0.1MPa≤E2≤1MPa.

4. The battery assembly according to any one of claims 1-3, wherein, 0.8≤ζ≤1.

5. The battery assembly according to any one of claims 1-4, wherein, 0.01≤λ<0.6, preferably 0.05≤λ≤0.

2.

6. The battery assembly according to any one of claims 1-5, wherein, 0.01MN≤Fmax≤0.5MN.

7. The battery assembly according to any one of claims 1-6, wherein, 0.01m 2 ≤A≤0.2m 2 。 8. The battery assembly according to any one of claims 1-7, wherein, 0.5%≤V1≤50%, preferably 5%≤V1≤35%; wherein, V1 is the volume percentage of the skeleton (22) to the total volume of the skeleton (22) and the heat-absorbing material (23) at room temperature.

9. The battery assembly according to any one of claims 1-8, wherein, The frame (22) includes multiple holes, which are filled with the heat-absorbing material.

10. The battery assembly according to any one of claims 1-9, wherein, The heat-absorbing element (20) is provided between any two adjacent individual cells (10).

11. The battery assembly according to any one of claims 1-10, wherein, Along the first direction, the heat-absorbing element (20) is provided between the single cell (10) and the housing 11.

12. The battery assembly according to any one of claims 1-10, wherein, The single cell (10) is a square single cell, and the heat-absorbing element (20) is disposed close to the large surface of the single cell.

13. An electrical appliance, wherein, Includes the battery assembly (1) as described in any one of claims 1-12.

14. An energy storage system (40), wherein, Includes the battery assembly (1) as described in any one of claims 1-12.

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