Battery assembly and electric equipment

Abstract

The invention provides a battery assembly and electric equipment. The battery assembly comprises at least two single battery packs and partition plates located between the two adjacent single battery packs. The partition plate comprises a xonotlite plate, the xonotlite plate comprises xonotlite materials, and the density of the xonotlite plate is larger than 170 kg / m < 3 > and smaller than 600 kg / m < 3 >. The problems of thermal diffusion and thermal runaway can be effectively inhibited, and the performance such as thermal safety of the battery assembly is improved.

Description

Technical Field

[0001] The present invention relates to the field of electrochemical devices, and in particular to a battery assembly and electrical equipment. Background Art

[0002] In recent years, with the rapid development of the new energy power battery and energy storage industry and the iterative upgrading of technology, the high integration of battery components (or battery modules) systems has brought about a significant increase in battery energy density and driving range. At the same time, it has put forward higher requirements on the thermal safety of battery components. For example, higher requirements are put forward on the thermal safety protection of battery component systems when facing various harsh working conditions during their life cycle, so as to avoid the occurrence of problems such as battery thermal runaway.

[0003] Specifically, when battery components are exposed to mechanical abuse (such as collision, extrusion, and puncture of electrical equipment (such as vehicles) using the battery), electrical abuse (such as overcharging, over-discharge, and short circuit), thermal abuse (improper temperature management), and other operating conditions, single or multiple single cells will often cause thermal runaway. It is necessary to prevent the spread of thermal runaway (i.e., prevent heat diffusion) to avoid thermal runaway in other single cells and cause more serious thermal safety problems.

[0004] By placing a thermal insulation sheet (or partition) between adjacent batteries, heat diffusion can be suppressed to a certain extent. However, due to factors such as the poor heat resistance, high thermal conductivity, and low mechanical strength of existing partitions, the improvement effect of existing thermal insulation sheets on suppressing heat diffusion is limited. In particular, it is not suitable for blocking heat diffusion between battery packs with multiple single cells (when a partition is placed between two battery packs, since each battery pack has multiple single cells, the pressure on the partition is greater, and when the single cells in one or several battery packs experience thermal runaway due to mechanical abuse, electrical abuse, thermal abuse, etc., the temperature generated is often higher, which is more likely to cause the partition to be damaged, and thus cannot effectively prevent heat from diffusing to the single cells in the adjacent battery pack, causing the single cells in the adjacent battery pack to experience thermal runaway).

[0005] For example, currently, aerogel insulation sheets (or aerogel separators) are mainly placed between adjacent single cells to block heat diffusion. The aerogels used mainly include pre-oxidized silk aerogel, glass fiber aerogel and ceramic fiber aerogel. Aerogel insulation sheets are mainly used to solve the heat diffusion of single-cell low-capacity cells. However, when faced with mechanical abuse (such as collisions of electrical equipment (such as cars), puncture of multiple cells (single cells) by sharp objects), and high-temperature and high-capacity batteries or battery components, aerogel insulation sheets are easily damaged and cannot effectively suppress heat diffusion. For example, the aerogel separator is squeezed by the cells. The pressure causes its thickness to decrease. The continuous pressure, high temperature and heat damage the structure of the aerogel insulation sheet, causing the heat generated by the battery that has experienced thermal runaway to spread to the adjacent batteries, causing the adjacent batteries to exceed their safe temperature, thereby triggering thermal runaway (especially when the aerogel separator is spaced between battery packs with multiple single cells, the aerogel separator is squeezed by the multiple single cells, and the temperature of the multiple single cells when thermal runaway occurs is often higher, which makes it easier to cause the aerogel separator to be damaged, causing the heat to spread to the single cells in the adjacent battery pack, causing the single cells in the adjacent battery pack to experience thermal runaway). Summary of the Invention

[0006] The present invention provides a battery assembly and electrical equipment to at least solve the problem in the prior art that heat diffusion cannot be effectively suppressed due to factors such as poor heat resistance, high thermal conductivity, and low mechanical strength of the separator.

[0007] In one aspect of the present invention, a battery assembly is provided, comprising at least two groups of single battery cells and a separator located between two adjacent groups of the single battery cells; the separator comprises a xonotlite board, the xonotlite board comprising xonotlite material, the density of the xonotlite board being greater than 170 kg / m 3 And less than 600kg / m 3 .

[0008] According to one embodiment of the present invention, the density of the hard calcium silicate board is 200 kg / m 3 ~500kg / m 3 .

[0009] According to one embodiment of the present invention, the density of the hard calcium silicate board is 300 kg / m 3 ~400kg / m 3 .

[0010] According to one embodiment of the present invention, the xonotlite material includes microspheres formed of xonotlite fibers.

[0011] According to one embodiment of the present invention, the diameter of the xonotlite fiber is nanometer-scale.

[0012] According to one embodiment of the present invention, the compressive strength of the hard calcium silicate board at room temperature and pressure is greater than or equal to 2 MPa; and / or, the compressive strength of the hard calcium silicate board after being kept at temperature T1 and normal pressure for 60 min±5 min is greater than or equal to 2 MPa, 600°C≤T1≤1000°C; and / or, the compressive strength of the hard calcium silicate board after being kept at temperature T2 and pressure P1 for 60 min±5 min is greater than or equal to 2 MPa, 600°C≤T2≤1000°C, 1.8 MPa≤P1≤2.4 MPa; and / or, the flexural strength of the hard calcium silicate board at room temperature and pressure is greater than or equal to 1 MPa.

[0013] According to one embodiment of the present invention, the ablation rate of the xoasil board after being treated at 600±10° C. for 60±5 minutes is less than 10%.

[0014] According to one embodiment of the present invention, the thermal conductivity of the xonotlite board at a temperature of 600±10° C. is less than 0.1 W / m·K.

[0015] According to one embodiment of the present invention, the moisture content of the xonotlite board is less than 7%.

[0016] According to one embodiment of the present invention, the hard calcium silicate board includes reinforcing fibers, which include glass fibers and / or plant fibers; and / or the hard calcium silicate board includes a sunscreen, which includes one or more of silicon carbide particles, titanium dioxide particles, zirconium dioxide particles, ferrosoferric oxide particles, and potassium hexatitanate whiskers.

[0017] According to one embodiment of the present invention, the separator further includes a packaging film that packages the xonotlite board.

[0018] According to one embodiment of the present invention, the packaging film comprises a polymer film; and / or the packaging film has a thickness of 10 μm to 100 μm.

[0019] According to one embodiment of the present invention, the insulation resistance of the separator is greater than or equal to 20 MΩ; and / or the withstand voltage leakage current of the separator is less than 3 mA.

[0020] According to one embodiment of the present invention, the thickness of the separator is 6 mm to 50 mm.

[0021] According to one embodiment of the present invention, the thickness of the partition is 13.5 mm-28.2 mm.

[0022] According to an embodiment of the present invention, at least one of the battery packs includes a plurality of battery cells.

[0023] Another aspect of the present invention provides an electrical device comprising the above-mentioned battery assembly.

[0024] The battery assembly and electrical equipment provided by the present invention use a separator between the battery assemblies, and the separator used includes a hard calcium silicate board containing a hard calcium silicate material, and the density of the hard calcium silicate board is greater than 170kg / m 3 And less than 600kg / m 3 The separator has good heat resistance, low thermal conductivity, high mechanical strength and other properties, and has good thermal insulation ability. When the single battery in the battery assembly suffers from thermal runaway due to mechanical abuse, electrical abuse, thermal abuse and other factors, it can effectively suppress the generated heat from diffusing to the adjacent single battery group, avoiding the thermal runaway problem of the single battery in the adjacent single battery group; at the same time, the separator has high mechanical strength and good heat resistance, and is not easily damaged by factors such as the extrusion of the single battery and the high temperature generated by the thermal runaway of the single battery, thereby effectively suppressing heat diffusion. The separator has the advantages of high-temperature fire resistance, light weight and high strength, good thermal insulation ability, and low cost, and can effectively improve the thermal safety and other performance of the battery assembly. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A schematic structural diagram of a battery assembly according to an embodiment of the present invention;

[0026] Figure 2 This is the XRD spectrum of the hard calcium silicate board of Example 1 of the present invention (the ordinate is the peak intensity);

[0027] Figure 3 This is a SEM image of the hard calcium silicate board of Example 1 of the present invention;

[0028] Figure 4 This is an SEM image of the hard calcium silicate board of Example 1 of the present invention.

[0029] Explanation of reference numerals: 1: separator; 2: single cell; 201: first group of single cell groups; 202: second group of single cell groups; 203: third group of single cell groups. DETAILED DESCRIPTION

[0030] In order to enable those skilled in the art to better understand the scheme of the present invention, the present invention is further described in detail below. The specific embodiments listed below are only for describing the principles and features of the present invention. The examples are only used to explain the present invention and are not intended to limit the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts are within the scope of protection of the present invention.

[0031] An embodiment of the present invention provides a battery assembly, such as Figure 1As shown, the battery assembly includes at least two groups of single battery packs and a separator located between the two adjacent groups of single battery packs; the separator includes a hard calcium silicate board, the hard calcium silicate board includes a hard calcium silicate stone material, and the density of the hard calcium silicate board is greater than 170kg / m 3 And less than 600kg / m 3 .

[0032] In the embodiment of the present invention, the use of the above-mentioned separator between adjacent single-cell battery groups can effectively suppress heat diffusion and improve the thermal safety and other performance of the battery. Specifically, according to the inventor's research, the above-mentioned separator has good heat resistance, low thermal conductivity, high mechanical strength and other properties, and has good thermal insulation capabilities. When the single cells in the battery assembly experience thermal runaway due to mechanical abuse, electrical abuse, thermal abuse and other factors, it can effectively suppress the generated heat from spreading to the adjacent single-cell battery group, avoiding the thermal runaway problem of the single cells in the adjacent single-cell battery group; at the same time, the separator has high mechanical strength and good heat resistance, and is not easily damaged by factors such as the extrusion of the single cells and the high temperature generated by the thermal runaway of the single cells, thereby effectively suppressing heat diffusion. The separator has the advantages of high-temperature fire resistance, light weight and high strength, good thermal insulation capacity, and low cost, and can effectively improve the thermal safety and other performance of the battery assembly.

[0033] In an embodiment of the present invention, any single cell battery pack includes at least one single cell, that is, it may include one single cell, or include multiple single cells, for example, 2, 5, 8, 10, 14, 17, 20, 26, 30, or the number of single cells is in a range consisting of any two of them, or more.

[0034] In some embodiments, at least one battery cell group includes a plurality of battery cells. For example, there are at least two adjacent battery cell groups, each of which includes a plurality of battery cells. A separator is disposed between the two adjacent battery cell groups.

[0035] In the related art, due to factors such as poor heat resistance, high thermal conductivity, and low mechanical strength, existing separators are not suitable for use between battery packs with multiple cells. Specifically, when a separator is placed between two battery packs with multiple cells, the multiple cells in each battery pack exert greater pressure on the separator. Furthermore, when the cells in one or more battery packs experience thermal runaway due to mechanical, electrical, or thermal abuse, the generated temperatures are often higher, making it more likely that the separator will fail. Consequently, the separator cannot effectively prevent heat from spreading to the cells in adjacent battery packs, causing thermal runaway in the cells in the adjacent battery packs. However, in embodiments of the present invention, by employing a separator comprising the aforementioned hard calcium silicate board, the separator can be used between battery packs with multiple cells, effectively suppressing heat diffusion between such high-capacity battery packs and improving the thermal safety and other performance of the battery assembly.

[0036] According to the inventors' research and analysis, there is a certain correlation between the density of the hard calcium silicate board and its mechanical strength, thermal conductivity, and other properties. Specifically, the mechanical strength of the hard calcium silicate board tends to decrease as the density of the hard calcium silicate board decreases. The higher the density of the hard calcium silicate board, the higher its compaction and thermal conductivity, which in turn deteriorates the thermal insulation capability of the hard calcium silicate board. When separators are used in battery assemblies, the separators must not only achieve the required thermal insulation capability but also meet high mechanical strength requirements. This is mainly because when a single cell in a battery assembly experiences thermal runaway, the temperature in the battery assembly rises. The single cells in the battery assembly expand due to the heat, squeezing the separator and causing cracks in the separator. When the squeezing force on the separator reaches a critical value (this critical value corresponds to the lower critical value of the mechanical strength of the separator), the cracks in the separator penetrate the entire separator, allowing heat to be transferred through the cracks to the cells in adjacent cells, further triggering thermal runaway in the adjacent cells and rendering the thermal insulation effect of the separator ineffective.

[0037] The inventors have found that in a battery assembly, a separator comprising a hard calcium silicate board is used between adjacent single battery groups. When a single battery in a single battery group experiences thermal runaway, when the density ρ of the hard calcium silicate board is 170kg / m 3 <ρ<600kg / m 3 When the density ρ of the hard calcium silicate board is as low as 170kg / m3, the temperature of the adjacent single cells will not rise much (for example, after 15 minutes of thermal diffusion, the temperature of the adjacent single cells is generally below 170℃, for example, between 150℃ and 170℃). 3When the temperature of the adjacent single cells increases sharply (for example, after 15 minutes of thermal diffusion, the temperature of the adjacent single cells reaches above 670°C), and thermal runaway occurs. The reason for this is that for the separator used in the battery assembly, 170kg / m 3 The density of the hard calcium silicate board has basically reached the lower critical value, that is, when the density of the hard calcium silicate board is 170kg / m 3 When the lower critical value of the mechanical strength of the separator is basically reached, a serious crack is generated on the separator, and the crack basically penetrates the separator, so that the heat generated by the single battery that has thermal runaway spreads through the crack, causing thermal runaway problems in adjacent single batteries.

[0038] In addition, when the density of the hard calcium silicate board is as high as 600kg / m 3 When the temperature of the adjacent single cells increases sharply (for example, after 15 minutes of thermal diffusion, the temperature of the adjacent single cells reaches above 670°C), and thermal runaway occurs. The reason for this is that for the separator used in the battery assembly, 600kg / m 3 The upper critical value of the density of the hard calcium silicate board has been basically reached, so that the thermal conductivity of the hard calcium silicate board has basically reached the critical value, the thermal insulation ability of the partition fails, and the heat generated by the single cell that has thermal runaway is transferred to the adjacent single cell through the partition, causing the thermal runaway temperature of the adjacent single cell.

[0039] Therefore, the embodiment of the present invention adopts a density greater than 170kg / m 3 And less than 600kg / m 3 The xonotlite can inhibit heat diffusion and avoid thermal runaway problems in adjacent single cells, thereby improving the thermal safety and other performance of battery components.

[0040] In the embodiment of the present invention, the single cell may be a conventional battery in the art, such as a power battery, and specifically may be a lithium-ion battery, such as a soft-pack lithium-ion battery.

[0041] In some embodiments, the capacity of the single battery can be 50Ah to 350Ah, for example, 50Ah, 70Ah, 90Ah, 100Ah, 120Ah, 140Ah, 150Ah, 153Ah, 170Ah, 190Ah, 200Ah, 210Ah, 217.1Ah, 220Ah, 230Ah, 240Ah, 250Ah, 270Ah, 290Ah, 300Ah, 310Ah, 326Ah, 330Ah, 340Ah, 350Ah or a range consisting of any two of them.

[0042] In the embodiments of the present invention, the individual battery groups in the battery assembly and the individual cells within the individual battery groups may be connected using conventional methods in the art, without particular limitation. For example, for any individual battery group comprising multiple individual cells, these individual cells may be electrically connected using conventional methods in the art, such as in series, parallel, or hybrid connection, without separators or other structures being provided between adjacent individual cells in the individual battery group.

[0043] After further research, the density of the above-mentioned hard calcium silicate board can be 200kg / m 3 ~500kg / m 3 , which is conducive to further suppressing the thermal diffusion problem of battery components and improving the thermal safety and other performance of battery components.

[0044] For example, the density of the hard calcium silicate board can be 200 kg / m 3 , 250kg / m 3 、300kg / m 3 、350kg / m 3 , 400kg / m 3 450kg / m 3 , 500kg / m 3 or a range consisting of any two of them.

[0045] In some preferred embodiments, the density of the hard calcium silicate board can be 300 kg / m 3 ~400kg / m 3 , which helps to further suppress the thermal diffusion problem of battery components and improve the thermal safety of battery components.

[0046] In an embodiment of the present invention, the xonotlite material may include xonotlite fibers, and the diameter of the xonotlite fibers may be nanometer-scale, that is, the xonotlite board is a nano-xonotlite board, wherein the diameter of the xonotlite fibers is generally 50nm to 400nm, for example, 50nm, 100nm, 150nm, 200nm, 250nm, 300nm, 350nm, 400nm, or a range consisting of any two thereof. By using nano-scale xonotlite boards, which have a lower thermal conductivity, the thermal diffusion problem of the battery assembly can be further suppressed, the thermal safety of the battery assembly can be improved, and it is also conducive to the production of nano-xonotlite boards through hydrothermal dynamic reaction.

[0047] Specifically, the xonotlite material is dispersed in the xonotlite board in a granular form (i.e., the xonotlite board includes xonotlite particles). The xonotlite material may include microspheres formed by xonotlite fibers (i.e., xonotlite particles). The microspheres are generally hollow microspheres formed by xonotlite fibers. The particle size of the microspheres is micron-sized. The particle size of the microspheres is generally less than or equal to 200 μm, specifically 20 μm to 200 μm, for example, 20 μm, 50 μm, 80 μm, 100 μm, 130 μm, 150 μm, 180 μm, 200 μm, or a range consisting of any two thereof. The xonotlite board material has a hollow microsphere structure formed by xonotlite fibers, which is beneficial for heat insulation, can further suppress the thermal diffusion problem of the battery assembly, improve the thermal safety of the battery assembly, and is also beneficial for preparing nano xonotlite boards through hydrothermal dynamic reaction.

[0048] In the embodiment of the present invention, the diameter of the xonotlite fiber refers to the average diameter of the xonotlite fiber in the xonotlite board, and the particle size of the microspheres refers to the average particle size of the microspheres formed by the xonotlite fibers in the xonotlite board. The presence form of xonotlite in the xonotlite board (for example, detecting the xonotlite fibers and the microspheres formed by the xonotlite fibers), the average diameter of the xonotlite fibers, the average particle size of the microspheres formed by the xonotlite fibers, and other characteristics can be measured by performing scanning electron microscopy (SEM) analysis on the xonotlite board and other methods.

[0049] In the embodiment of the present invention, the crystal structure of the xonotlite in the xonotlite board can be determined by X-ray diffraction (XRD) analysis.

[0050] In some embodiments, the compressive strength σ1 of the above-mentioned hard calcium silicate board at room temperature (25°C±5°C) and normal pressure can be greater than or equal to 2MPa, and σ1 is, for example, greater than or equal to 2.4MPa, which is conducive to the separator having higher mechanical strength and avoiding its damage in the battery pack due to factors such as the extrusion of single cells and the high temperature generated by thermal runaway of single cells, thereby suppressing the thermal diffusion problem of the battery assembly and improving the thermal safety of the battery assembly.

[0051] Illustratively, σ1 is 2 MPa, 2.4 MPa, 2.6 MPa, 3 MPa, 3.5 MPa, 4 MPa, 4.2 MPa, 4.5 MPa, 5 MPa, 5.4 MPa, 6 MPa, 6.5 MPa, 7 MPa, 7.5 MPa, 8 MPa, or a range consisting of any two thereof.

[0052] In some embodiments, the compressive strength σ2 of the above-mentioned hard calcium silicate board after being kept (placed) at temperature T1 and normal pressure for 60min±5min can be greater than or equal to 2MPa, 600℃≤T1≤1000℃ (that is, the compressive strength σ2 of the hard calcium silicate board after treatment at high temperature (T1) and normal pressure can be greater than or equal to 2MPa), and σ2 is, for example, greater than or equal to 2.4MPa, which is conducive to the separator having higher mechanical strength and avoiding its damage in the battery pack due to factors such as extrusion of single cells and high temperature generated by thermal runaway of single cells, thereby suppressing the thermal diffusion problem of the battery assembly and improving the thermal safety of the battery assembly.

[0053] Illustratively, σ2 is 2 MPa, 2.4 MPa, 2.75 MPa, 3 MPa, 3.5 MPa, 4 MPa, 4.5 MPa, 5 MPa, 5.6 MPa, 6 MPa, 6.5 MPa, 7 MPa, 7.5 MPa, 7.8 MPa, 8 MPa, or a range consisting of any two of them.

[0054] Specifically, the compressive strength σ3 of the above-mentioned hard calcium silicate board after being kept (placed) at temperature T2 and pressure P1 for 60min±5min can be greater than 2MPa, 600≤T2≤1000℃, 1.8Mpa≤P1≤2.4Mpa (that is, the compressive strength of the hard calcium silicate board after being treated under high temperature (T2) and high pressure (P1) conditions can be greater than 2MPa), σ3 is, for example, greater than or equal to 2.4MPa, which is conducive to the separator having higher mechanical strength and avoiding its damage in the battery pack due to factors such as the extrusion of the single battery and the high temperature generated by the thermal runaway of the single battery, thereby suppressing the thermal diffusion problem of the battery assembly and improving the thermal safety of the battery assembly.

[0055] Illustratively, σ3 is 2 MPa, 2.4 MPa, 3 MPa, 3.5 MPa, 4 MPa, 4.2 MPa, 4.5 MPa, 5 MPa, 5.3 MPa, 5.6 MPa, 6 MPa, 6.5 MPa, 7 MPa, 7.3 MPa, 7.5 MPa, or a range consisting of any two of them.

[0056] In the embodiment of the present invention, the compressive strength σ1 of the hard calcium silicate board at room temperature and pressure can be directly measured under normal temperature, pressure and humidity conditions; the compressive strength σ2 of the hard calcium silicate board treated at high temperature (T1) and normal pressure can be obtained by keeping the hard calcium silicate board at high temperature (T1) and normal pressure for 60min±5min, and then measuring it under normal temperature, pressure and humidity conditions; the compressive strength σ3 of the hard calcium silicate board treated at high temperature (T2) and high pressure (P1) can be obtained by keeping the hard calcium silicate board at high temperature (T2) and high pressure (P1) for 60min±5min, and then measuring it under normal temperature, pressure and humidity conditions.

[0057] Specifically, the above-mentioned compressive strength (σ1, σ2, σ3) of the hard calcium silicate board can be tested with reference to "GB / T 5486-2008 Test Method for Inorganic Hard Thermal Insulation Products". The test is carried out under normal temperature, pressure and humidity conditions. There is no need to dry the hard calcium silicate board in advance. During the test, a universal testing machine is used to pressurize the hard calcium silicate board sample along the thickness direction of the hard calcium silicate board sample (loading pressure) until the sample is destroyed, and the yield strength is read (the turning point of the stress-strain curve is taken as the yield strength), which is the compressive strength; wherein, the sample size is 100mm×100mm×30mm, the loading rate is 10mm / min, and the inlet force is 5N.

[0058] In the embodiment of the present invention, a conventional universal testing machine in the field, such as an electronic universal testing machine, can be used. In specific implementation, an electronic universal testing machine (10KN) with the model number AGS-X-10KN can be used. When testing the above-mentioned compressive strength (σ1, σ2, σ3) of the hard calcium silicate board, the hard calcium silicate board sample can be pressurized (loaded with pressure) along the thickness direction of the hard calcium silicate board sample from the pressing surface of the hard calcium silicate board sample until the sample is destroyed, and the yield strength is read, which is the compressive strength; wherein, the pressing surface of the hard calcium silicate board sample refers to: in the process of preparing the hard calcium silicate board, when the slurry containing the hard calcium silicate material and other materials used to form the hard calcium silicate board is filter-filtered, the filter press equipment filters the slurry from one side of the slurry (hereinafter referred to as the pressing side), and after the filter press molding, the pressing side of the slurry corresponds to the pressing surface of the hard calcium silicate board.

[0059] In addition, the flexural strength σ4 of the above-mentioned hard calcium silicate board at room temperature (25℃±5℃) and normal pressure can be greater than 1MPa, which is conducive to the separator having higher mechanical strength and avoiding its damage in the battery pack due to factors such as the extrusion of single cells and the high temperature generated by thermal runaway of single cells, thereby suppressing the thermal diffusion problem of the battery assembly and improving the thermal safety of the battery assembly.

[0060] In the embodiment of the present invention, the flexural strength σ4 of the hard calcium silicate board under the above conditions can be measured by the following method with reference to "GB / T 5486-2008 Test Methods for Inorganic Rigid Thermal Insulation Products". When testing, the test is conducted at normal temperature, normal pressure, and normal humidity without prior drying.

[0061] In the embodiment of the present invention, a conventional universal testing machine in the art can be used to test the flexural strength of the hard calcium silicate board, for example, an electronic universal testing machine can be used. In specific implementation, an electronic universal testing machine (10KN) with a model of AGS-X-10KN can be used.

[0062] In addition, the ablation rate w of the above-mentioned hard calcium silicate board after being treated (heat-insulated) at 600±10°C for 60±5 minutes is less than 10% (that is, the ablation rate w of the hard calcium silicate board after long-term heat resistance is less than 10%), which is conducive to the separator having good heat resistance and other properties, avoiding its damage due to factors such as high temperature generated by thermal runaway of single cells in the battery pack, thereby suppressing the thermal diffusion problem of the battery assembly and improving the thermal safety of the battery assembly.

[0063] In an embodiment of the present invention, the ablation rate w of the hard calcium silicate board can be measured by the following process: weighing the mass m1 of the hard calcium silicate board; then keeping the hard calcium silicate board at 600±10°C for 60±5 minutes; then weighing the mass m2 of the hard calcium silicate board after keeping warm, and calculating the ablation rate w of the hard calcium silicate board according to w=(m1-m2) / m1.

[0064] In addition, the thermal conductivity of the above-mentioned hard calcium silicate board at a temperature of 600±10°C can be less than 0.1W / m·K, which is conducive to the separator having low thermal conductivity, playing a heat insulation role, suppressing the thermal diffusion problem of the battery assembly, and improving the thermal safety of the battery assembly.

[0065] In the embodiment of the present invention, the thermal conductivity of the hard calcium silicate board at a temperature of 600±10° C. (ie, the thermal conductivity of the hard calcium silicate board at 600±10° C.) can be measured with reference to YB / T 4130-2005.

[0066] In addition, the moisture content of the above-mentioned hard calcium silicate board can be less than 7%, for example, less than or equal to 5%, which is conducive to the hard calcium silicate board having better insulation properties, so that the partition between two adjacent groups of single battery cells can play a better insulating role, further improving the safety and other performance of the battery assembly.

[0067] In the embodiment of the present invention, the moisture content of the hard calcium silicate board = (M1-M2) / M×100%, where M1 is the mass of the hard calcium silicate board in its natural state, and M2 is the mass of the hard calcium silicate board after drying at 110°C±5°C. In specific implementation, the moisture content of the hard calcium silicate board can be measured with reference to "GB / T5486-2008 Test Method for Inorganic Rigid Thermal Insulation Products". When testing the moisture content, the mass M1 of the specimen (hard calcium silicate board) in its natural state is weighed on a balance. After the specimen is kept at a constant temperature of 110°C in an oven for 3 hours, the mass M3 of the specimen is weighed again. Subsequently, the specimen is dried at 110°C to a constant weight M4, and then transferred to a dryer and cooled to room temperature. The criterion for constant mass is that the rate of change in the mass of the specimen weighed twice at a constant temperature of 3 hours is less than 0.2% (i.e., (M4-M3) / M3<0.2%). Then, M3 is used as the mass M2 of the hard calcium silicate board after drying at 110°C±5°C. The moisture content of the hard calcium silicate board is calculated according to moisture content=(M1-M2) / M1*100%.

[0068] In addition, the above-mentioned hard calcium silicate board may also include reinforcing fibers, which may include glass fibers and / or plant fibers. The plant fibers may include materials such as pulp, which are beneficial to improving the mechanical strength and other properties of the diaphragm, inhibiting the thermal diffusion problem of the battery assembly, and improving the thermal safety of the battery assembly.

[0069] In addition, the above-mentioned hard calcium silicate board may also include additives such as sunscreens. The sunscreen (anti-infrared radiation material) may include one or more of silicon carbide particles, titanium dioxide particles, zirconium dioxide particles, ferrosoferric oxide particles, and potassium hexatitanate whiskers.

[0070] In an embodiment of the present invention, a method for preparing a xonotlite board may include: mixing a silicon source, a calcium source, and water and reacting them, specifically, performing a hydrothermal dynamic reaction, to synthesize a slurry containing xonotlite (crystal); then adding reinforcing fibers and / or additives and other components to the slurry, and then performing filter press molding (specifically, mold filter press molding may be used), drying the obtained molded product, and then performing special-shaped processing and other processes to obtain a xonotlite board (xonotlite crystal product) of a preset shape.

[0071] In some embodiments, the reaction temperature of the above reaction can be 210°C to 230°C, for example, 210°C, 215°C, 220°C, 225°C, 230°C or a range consisting of any two thereof, and the reaction time can be 8h to 14h, for example, 8h, 10h, 12h, 14h or a range consisting of any two thereof.

[0072] Specifically, the reaction is carried out in a reactor, and the pressure of the reactor (i.e., reaction pressure) can be 1.8 MPa to 2.4 MPa, for example, 2 MPa. In specific implementation, water vapor can be introduced into the reactor to adjust the pressure of the reactor to the above reaction pressure.

[0073] Specifically, in the preparation process of the xonotlite, after filter pressing, the formed product can be dried at a temperature of 80° C. to 120° C., for example, 100° C., and the drying time can be 2 h to 5 h, for example, 3 h.

[0074] Specifically, the silicon source may include a silicon dioxide (SiO 2 ) material, and specifically, a silicon dioxide material having a silicon dioxide (SiO 2 ) content of more than 98% may be used.

[0075] Specifically, the calcium source may include a calcium hydroxide material, and specifically a calcium hydroxide material with a purity of more than 90% may be used.

[0076] In an embodiment of the present invention, the density, compressive strength (such as σ1, σ2, σ3), tensile strength (σ4), ablation rate, moisture content and other properties of the xonotlite can be regulated by regulating the preparation conditions of the xonotlite. For example, the compressive strength (such as σ1, σ2, σ3) and tensile strength (σ4) of the prepared xonotlite can be regulated by regulating the reaction temperature, reaction time and other conditions in the preparation process of the xonotlite. The moisture content and other properties of the prepared xonotlite can be regulated by regulating the drying temperature and other conditions.

[0077] In addition, the above-mentioned separator may also include a packaging film for packaging the hard calcium silicate board. The packaging film is wrapped around the outside of the hard calcium silicate board, which is beneficial to protecting the hard calcium silicate board and improving the wear resistance and other properties of the separator. At the same time, it prevents the hard calcium silicate board from directly contacting the single battery in the battery assembly, thereby avoiding the problem of the hard calcium silicate board generating powder and puncturing the single battery, and the water volatilized from the hard calcium silicate board affecting the electrochemical properties of the single battery, thereby further improving the safety and electrochemical properties of the battery assembly.

[0078] Specifically, the encapsulation film may include a polymer film, such as a multilayer co-extruded polyolefin heat shrinkable film (POF), a polyvinyl chloride (PVC) film, a polyethylene (PE) film, a polypropylene (PP) film, and a cross-linked film formed by cross-linking at least two of the polymer materials forming these films (single film) or multiple types (composite film).

[0079] During specific implementation, the hard calcium silicate board can be heat-shrink packaged to wrap a packaging film on the surface of the hard calcium silicate board.

[0080] In some embodiments, the thickness of the packaging film may be 10 μm to 100 μm, for example, 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm or any two thereof, preferably 30 μm to 50 μm.

[0081] In addition, the insulation resistance of the separator may be greater than or equal to 20 MΩ, and further may be greater than or equal to 500 MΩ. The separator has good insulation properties, which is beneficial for further improving the safety and other performance of the battery module.

[0082] Generally speaking, when no packaging film is provided on the surface of the hard calcium silicate board, the insulation resistance of the partition (also the insulation resistance of the hard calcium silicate board) is relatively small, for example, 20-40MΩ; when the partition includes a packaging film provided on the surface of the hard calcium silicate board, the insulation resistance of the partition is relatively large, specifically greater than or equal to 500MΩ, which is conducive to the partition having better insulation properties and further improving the electrochemical performance of the battery assembly.

[0083] In addition, the withstand voltage leakage current of the above-mentioned separator can be less than 3 mA. Using the separator between the single battery groups in the battery assembly is beneficial to further improve the safety and other performance of the battery assembly.

[0084] In the embodiment of the present invention, the insulation resistance of the partition can be tested with reference to "GB / T 31838.4-2019 Dielectric and resistance characteristics of solid insulating materials Part 4: Resistance characteristics (DC method) Insulation resistance".

[0085] In the embodiment of the present invention, the leakage current (ie, withstand voltage leakage current) of the separator can be tested with reference to GB / T 1408.1-2016 Electric strength test method of insulating materials Part 1 Test at power frequency.

[0086] In an embodiment of the present invention, after removing the packaging film of the hard calcium silicate board in the partition, the compressive strength (σ1, σ2, σ3), flexural strength σ4, ablation rate w, thermal conductivity, moisture content and other characteristics of the hard silicon partition can be tested.

[0087] In some embodiments, the thickness of the above-mentioned partition can be 6 mm to 50 mm, for example, 6 mm, 10 mm, 11 mm, 12 mm, 12.5 mm, 15 mm, 17 mm, 20 mm, 22 mm, 25 mm, 28.2 mm, 28.5 mm, 29 mm, 30 mm, 40 mm, 50 mm or a range consisting of any two of them, preferably 12.5 mm to 28.2 mm.

[0088] An embodiment of the present invention further provides an electrical device including the above-mentioned battery assembly. The electrical device has corresponding advantages to the above-mentioned battery assembly, which will not be described in detail.

[0089] The electrical equipment in the embodiments of the present invention can be conventional electrical equipment in this field, such as power equipment (such as electric vehicles, electric cars), electronic equipment (such as mobile phones, tablets, laptops, digital cameras, etc.), wearable devices (such as watches, bracelets, VR glasses, etc.), energy storage power stations, etc., without special restrictions.

[0090] The present invention is further described below through specific examples.

[0091] Example 1

[0092] 1. Preparation of separator

[0093] A silica material (SiO2 content of 98% or more) and a calcium hydroxide material (Ca(OH)2 purity of 90% or more) are added to a batching tank, water is added thereto, and then a hydrothermal dynamic reaction is carried out in an autoclave (water vapor is introduced into the autoclave during the reaction so that the pressure in the autoclave reaches the reaction pressure) to obtain a slurry containing xonotlite; wherein the reaction temperature is 210° C., the reaction time is 8 hours, and the reaction pressure is 2 MPa;

[0094] After adding glass fiber and ferric oxide to a slurry containing xonotlite, the mixture is filter-pressed in a mold and then dried (drying temperature is 100°C for 3 hours). The resulting molded product is then processed through special-shaped processing and cutting to produce a xonotlite crystalline product (i.e., a xonotlite board) of a predetermined thickness and shape. The thickness of the xonotlite board is 18 mm.

[0095] The hard calcium silicate board is heat-shrink-sealed using POF, so that a packaging film (ie, POF) is wrapped around the surface of the hard calcium silicate board to obtain a separator; wherein the thickness of the packaging film is 30 μm.

[0096] 2. Battery components and their thermal diffusion test

[0097] like Figure 1 As shown, the battery assembly consists of three groups of single battery groups, which are the first group of single battery groups, the second group of single battery groups and the third group of single battery groups (i.e., the second group of single battery groups is located between the first group of single battery groups and the third group of single battery groups). Each two adjacent groups of single battery groups are separated by a partition (i.e., a partition is provided between the first group of single battery groups and the second group of single battery groups, and a partition is provided between the second group of single battery groups and the third group of single battery groups). Each group of single battery groups consists of 17 single batteries ( Figure 1 Only the single cells in the first single cell group that are closest to the second single cell group and the single cells in the third single cell group that are closest to the second single cell group are shown in FIG.

[0098] The capacity of the single cell is 217.1Ah, the length is 625mm, the width is 130mm, and the thickness is 18mm (the size of the separator used is basically the same as the size of the single cell); the single cell is charged to a full charge (i.e., 100% SOC) state, the temperature of the single cell and the battery assembly is controlled to 45°C, and the middle single cell in the second group of single cells is needle-punctured at a speed of 1mm / s (there are 8 single cells between this single cell and the first group of single cells, and 8 single cells between this single cell and the third group of single cells). The needle-puncture is stopped immediately when the middle single cell loses control (smoke appears), and then a diffusion time of 15 minutes is maintained. Then, the temperature of each single cell in the second group of single cells is tested, and the temperature of the first group of single cells is tested. The temperatures of the cells closest to the second cell group in the battery pack, and the temperatures of the cells closest to the second cell group in the third cell group, were measured. The temperatures of the 17 cells in the second cell group were measured to be between 576°C and 891°C. The temperatures of the cells closest to the second cell group in the first cell group, and the temperatures of the cells closest to the second cell group in the third cell group, were both approximately 160°C. This indicates that the separator effectively prevented heat generated by thermal runaway in the cells in the second cell group from diffusing to the cells in the first and third cell groups. In other words, virtually no thermal diffusion occurred in the battery assembly, and no thermal runaway occurred in the cells in the first and second cell groups.

[0099] Example 2 to Example 4, Comparative Example 1 to Comparative Example 2: The difference from Example 1 is that the hydrothermal dynamic reaction temperature, reaction time, reaction pressure, and drying temperature in the preparation process of the hard calcium silicate board, as well as the density of the hard calcium silicate board, the compressive strength σ1 at room temperature (25±5°C) and normal pressure, the compressive strength σ2 after keeping warm at temperature T1 (T1=600°C) and normal pressure for 60 minutes, the compressive strength σ3 after keeping warm at temperature T2 (T1=600°C) and pressure P1 (P1=2MPa) for 60 minutes, the flexural strength σ4 of the hard calcium silicate board at room temperature and normal pressure, the ablation rate w of the hard calcium silicate board after keeping warm at 600°C for 60 minutes, the thermal conductivity of the hard calcium silicate board at 600°C, the moisture content of the hard calcium silicate board, the insulation resistance of the separator, the withstand voltage leakage current of the separator, etc. are different. See Table 1 and Table 2 for details. Except for the differences shown in Table 1 and Table 2, the other conditions are the same.

[0100] Example 5: The differences from Example 1 are as follows: (1) Each battery pack consists of 14 battery cells, each with a capacity of 153 Ah, a length of 948 mm, a width of 90 mm, and a thickness of 13.5 mm (the dimensions of the separator used are substantially the same as those of the battery cells); and (2) the thickness of the cut hard calcium silicate board (13.5 mm) is different from that of Example 1. The remaining conditions are the same as those of Example 1.

[0101] Example 6: The differences from Example 1 are as follows: (1) Each battery pack consists of 26 battery cells, each with a capacity of 326 Ah, a length of 880 mm, a width of 113 mm, and a thickness of 28.2 mm (the dimensions of the separator used are substantially the same as those of the battery cells); and (2) the thickness of the cut xerosilicon board (28.2 mm) is different from that of Example 1. All other conditions are the same as those of Example 1.

[0102] Example 7: The difference from Example 1 is that the hard calcium silicate board is not heat-shrink-molded, that is, the surface of the hard calcium silicate board is not provided with a packaging film. In other words, the separator of Example 7 is a hard calcium silicate board without a packaging film. The other conditions are the same as those of Example 1.

[0103] Among them, when testing the compressive strength σ2 of the hard calcium silicate board after being kept at T1 and normal pressure for 60 minutes, Table 2 shows the test results when T1=600℃. After the hard calcium silicate board is kept at normal pressure and in the temperature range of 600≤T1≤1000℃ for 60min±5min, the measured compressive strength σ2 is basically consistent with the test result when T1=600℃.

[0104] In addition, when testing the compressive strength σ3 of the hard calcium silicate board after being kept at T2 and P1 for 60 minutes, Table 2 shows the test results when T2 = 600°C and P1 = 2MPa. After the hard calcium silicate board is kept in the temperature range of 600≤T1≤1000°C and the pressure range of 1.8Mpa≤P1≤2.4Mpa for 60min±5min, the measured compressive strength σ3 is basically consistent with the test results when T2 = 600°C and P1 = 2MPa.

[0105] Comparative Example 3: The difference from Example 1 is that the partition in Example 1 is replaced by glass fiber aerogel, and the density of glass fiber aerogel is 240kg / m 3 , thickness 18 mm, 1 MPa compression rate > 20%, thermal conductivity at 600° C. of 0.1 W / m·K; other conditions are the same as those in Example 1. The 1 MPa compression rate of the glass fiber aerogel is measured in accordance with the standard GB / T13480-2014.

[0106] XRD analysis was performed on the xonotlite boards of Examples 2 to 7, respectively. The XRD analysis process of the xonotlite board was as follows: the xonotlite board was ground into powder and then transferred to a sample table. The powder was tested on an XRD crystal diffractometer. After the test, the spectrum was compared with the standard crystal diffraction pattern to determine the crystal structure of xonotlite in the xonotlite board.

[0107] Specifically, XRD analysis was performed on the xonotlite boards of Examples 2 to 7, and it was found that the xonotlite material therein was mainly a xonotlite crystal structure. SEM analysis showed that the xonotlite material in the xonotlite boards was mainly hollow microspheres formed by nano-xonotlite fibers. The particle size of the nano-xonotlite fibers was nanometer-scale, and the particle size of the hollow microspheres was micrometer-scale. The xonotlite in Example 1 is used as an example to further illustrate: (1) The XRD spectrum obtained by performing XRD testing on the xonotlite board in Example 1 is shown in FIG. Figure 2 ,from Figure 2 It can be seen that the xonotlite board has the crystal structure of xonotlite (6CaO·6SiO2·H2O) ( Figure 2 SiO2 in the figure represents unreacted silicon dioxide material); (2) The SEM image obtained by SEM analysis of the hard calcium silicate board in Example 1 is shown in FIG. Figure 3 and Figure 4 ,from Figure 3 and Figure 4 It can be seen that xonotlite has a fiber structure with a nanometer diameter. Nano-xonotlite fibers are aggregated into hollow microspheres, and the microspheres and fibers are interwoven to form xonotlite boards.

[0108] Table 1 Hydrothermal dynamic reaction conditions and drying conditions during the preparation of hard calcium silicate board

[0109]

[0110] Table 2 Related parameters of hard calcium silicate board and separator

[0111]

[0112] Among them, the hard calcium silicate board in Example 2 produced relatively minor crack damage during the test of compressive strength σ3 (the crack did not penetrate the hard calcium silicate board), while the hard calcium silicate board in Comparative Example 1 produced serious crack damage during the test of compressive strength σ3 (the crack penetrated the hard calcium silicate board).

[0113] Table 3 Test results (temperature of the single cells in each battery pack after 15 minutes of thermal diffusion)

[0114]

[0115] Note: In Table 3, “temperatures of the 17 cells in the second cell group” refers to the temperatures of these cells within the corresponding temperature range; “temperatures of adjacent cells” refers to the temperatures of the cells in the first cell group and the third cell group that are closest to the second cell group.

[0116] As can be seen from Table 3, in the test results of Comparative Example 1, after the middle single cell in the second group of single cell groups lost control and stopped being punctured, the separator broke after a diffusion time of 15 minutes (i.e., after 15 minutes of thermal diffusion), and the strength requirements could not be met. The temperature of the adjacent single cells reached 680°C, and thermal runaway occurred.

[0117] In addition, in the test results of Comparative Example 2, after the middle single cell in the second group of single cell groups lost control and stopped being punctured, after maintaining a diffusion time of 15 minutes (i.e., after 15 minutes of thermal diffusion), the temperature of the adjacent single cells reached 675°C, and the thermal diffusion between the single cell groups having multiple single cells could not be suppressed, that is, the thermal runaway of multiple cells could not be suppressed.

[0118] In addition, in the test results of Comparative Example 3, after the middle single cell in the second group of single cell batteries lost control and stopped needling, after maintaining a diffusion time of 15 minutes (i.e., after 15 minutes of thermal diffusion), the glass fiber aerogel was squeezed by the expansion force of the single cell in thermal runaway. The thickness of the squeezed glass fiber aerogel was about 14 mm, and the temperature of the adjacent single cell reached 700°C, which could not suppress the thermal runaway of multiple cells.

[0119] Compared with Comparative Examples 1 to 3, the battery components of Examples 1 to 7 adopt a pressure greater than 170 kg / m 3 And less than 600kg / m 3 The hard calcium silicate board can effectively suppress heat diffusion when thermal runaway occurs in the single battery in the second group of single battery groups, avoiding thermal runaway and other problems in the single batteries in the first group of single battery groups and the third group of single battery groups adjacent to the second group of single battery groups, thereby improving the thermal safety and other performance of the battery assembly.

[0120] In addition, compared with Example 2 and Example 4, Example 1 and Example 3 further adopt a density of 300 kg / m 3 ~400kg / m 3 The hard calcium silicate board has better mechanical strength and is not easy to break even after being treated under high temperature and high pressure. It is beneficial to effectively inhibit heat diffusion while improving the mechanical strength of the separator, further improving the thermal safety and service life of the battery components.

[0121] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A battery assembly, characterized in that: The invention comprises at least two groups of single battery packs and a partition between two adjacent groups of the single battery packs; the partition comprises a hard calcium silicate board, the hard calcium silicate board comprises a hard calcium silicate stone material, and the density of the hard calcium silicate board is greater than 170 kg / m 3 And less than 600kg / m 3 .

2. The battery assembly according to claim 1, wherein: The density of the hard calcium silicate board is 200kg / m 3 ~500kg / m 3 .

3. The battery assembly according to claim 2, wherein: The density of the hard calcium silicate board is 300kg / m 3 ~400kg / m 3 .

4. The battery assembly according to claim 1 or 2, characterized in that: The xonotlite material includes microspheres formed from xonotlite fibers.

5. The battery assembly according to claim 4, characterized in that The diameter of the xonotlite fiber is nanometer level.

6. The battery assembly according to any one of claims 1 to 5, characterized in that: The compressive strength of the hard calcium silicate board at room temperature and pressure is greater than or equal to 2MPa; And / or, the compressive strength of the hard calcium silicate board after being kept at temperature T1 and normal pressure for 60min±5min is greater than or equal to 2MPa, 600℃≤T1≤1000℃; And / or, the compressive strength of the hard calcium silicate board after being kept at temperature T2 and pressure P1 for 60min±5min is greater than or equal to 2MPa, 600℃≤T2≤1000℃, 1.8Mpa≤P1≤2.4Mpa; And / or, the flexural strength of the hard calcium silicate board at normal temperature and pressure is greater than or equal to 1 MPa.

7. The battery assembly according to any one of claims 1 to 6, characterized in that: The ablation rate of the hard calcium silicate board after being treated at 600±10° C. for 60±5 minutes is less than 10%.

8. The battery assembly according to any one of claims 1 to 7, characterized in that: The thermal conductivity of the hard calcium silicate board at a temperature of 600±10° C. is less than 0.1 W / m·K.

9. The battery assembly according to any one of claims 1 to 8, characterized in that: The water content of the hard calcium silicate board is less than 7%.

10. The battery assembly according to any one of claims 1 to 9, characterized in that: The hard calcium silicate board includes reinforcing fibers, and the reinforcing fibers include glass fibers and / or plant fibers; And / or, the xonotlite board includes a sunshade, and the sunshade includes one or more of silicon carbide particles, titanium dioxide particles, zirconium dioxide particles, ferrosoferric oxide particles, and potassium hexatitanate whiskers.

11. The battery assembly according to any one of claims 1 to 10, characterized in that: The separator further includes a packaging film that packages the hard calcium silicate board.

12. The battery assembly according to claim 11, wherein: The encapsulation film comprises a polymer film; And / or, the packaging film has a thickness of 10 μm to 100 μm.

13. The battery assembly according to any one of claims 1 to 12, characterized in that: The insulation resistance of the separator is greater than or equal to 20MΩ; And / or, the withstand voltage leakage current of the separator is less than 3 mA.

14. The battery assembly according to any one of claims 1 to 13, characterized in that: The thickness of the partition is 6 mm to 50 mm.

15. The battery assembly according to claim 14, wherein: The thickness of the partition is 13.5 mm to 28.2 mm.

16. The battery assembly according to any one of claims 1 to 15, characterized in that: At least one of the battery packs includes a plurality of battery cells.

17. An electrical device, characterized in that: A battery assembly comprising the battery assembly according to any one of claims 1 to 16.

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