Battery module with polyorganosiloxane foam barrier

Abstract

A battery module is provided that includes an array of spatially separated battery cells and a barrier material that contacts adjacent battery cells. The barrier material, which includes a polyorganosiloxane foam, a flame retardant, and hollow ceramic particles, provides flame resistance, compressibility, and thermal insulation.

Description

[Technical Field]

[0001] The present invention relates to a battery module insulated by a treated polyorganosiloxane foam barrier.

[0002] Rechargeable batteries, such as lithium-ion batteries (LiBs), are commonly used in a variety of applications, including electric vehicles (EVs) and grid energy storage systems. While LiBs possess desirable characteristics such as high energy density and stability, their practical use is currently limited due to safety concerns. Firstly, LiB cell failures can be caused by manufacturing defects, internal short circuits, overheating, overcharging, or mechanical shocks. Secondly, heat generated from a failed cell can propagate, potentially causing thermal runaway in adjacent cells. The rapid pressure increases resulting from these thermal events increase the risk of fire and explosion.

[0003] Thermal runaway can be mitigated by placing thermal barriers that provide insulation and flame resistance between cells in a LiB module. Commonly used thermal barriers such as aerogel, ceramic fiber, and mica board offer such properties, but aerogel and ceramic fiber have poor mechanical elasticity, while mica board has poor compressibility. On the other hand, blown silicone foam provides adequate compressibility and is suitable for low and medium energy density batteries, but it has the problem of insufficient insulation to prevent thermal runaway in very high energy density battery packs. Therefore, in the field of thermal barriers for rechargeable batteries, it is desirable to create barriers that provide insulation, flame resistance, and satisfactory compressibility. [Overview of the Initiative]

[0004] The present invention relates to a battery module comprising a shell containing an array of spatially separated battery cells and a barrier material in contact with adjacent battery cells, wherein the barrier material comprises, based on the weight of the barrier material, 35 to 95 weight percent of polyorganosiloxane foam, 1 to 30 weight percent of flame retardant, and 1 to 35 weight percent of hollow ceramic particles having a volume-average particle size in the range of 25 μm to 300 μm, and the barrier material has a density of 0.10 to 0.90 g / cm³. 3 We address the needs in this field by providing a battery module having a density in the range of [range].

[0005] The battery module of the present invention provides improved heat resistance and flame resistance for applications such as lithium-ion batteries. [Brief explanation of the drawing]

[0006] [Figure 1] This is a diagram of a battery module containing polyorganosiloxane foam material. [Modes for carrying out the invention]

[0007] The present invention relates to a battery module comprising a shell containing an array of spatially separated battery cells, and a barrier material in contact with adjacent battery cells, wherein the barrier material comprises, based on the weight of the barrier material, 35 to 95 weight percent of polyorganosiloxane foam, 1 to 30 weight percent of flame retardant, and 1 to 35 weight percent of hollow ceramic particles having a volume-average particle size in the range of 25 μm to 300 μm, and the barrier material has a density of 0.10 to 0.90 g / cm³. 3 This is a battery module having a density in the range of [value].

[0008] A barrier material that is thermally insulating, flame-resistant, and compressible foamed polyorganosiloxane can be prepared by modifying the method described in U.S. Patent No. 5,358,975. For example, a polydimethylsiloxane (a) functionalized with at least two, preferably at least three Si-H groups is brought into contact with one or more hydroxyl-containing compounds (b), which are water, alcohol, diol, polyol, or compounds containing at least one silanol group, a divinyl-functionalized polydimethylsiloxane (c), a hydrosilylation catalyst, such as a platinum-based catalyst (d), a flame retardant (e), and hollow ceramic particles (f) to form a crosslinked network of a thermally insulating, compressible, and flame-resistant foamed material having -Si-CH2-CH2-Si groups and -Si-OR- groups (wherein R is H, or a structural unit of alcohol, diol, polyol, or silanol (i.e., a reaction product)). The sum of components (a), (b), and (c) is in the range of 35 or 40 to 80 or 70 weight percent of the polyorganosiloxane foam.

[0009] It may be advantageous to prepare the barrier material using the following two-part approach. In a first container, a first portion of divinyl-functionalized polydimethylsiloxane, a first portion of a flame retardant, a hydrosilylation catalyst, a hydroxyl-containing compound or multiple compounds, and a first portion of hollow ceramic particles are blended to form Part A composition. In a second container, the remaining portion of divinyl-functionalized polydimethylsiloxane, a polymer resin blend which is a mixture of divinyl-functionalized polydimethylsiloxane and a crosslinked organopolysiloxane resin, the remaining portion of a flame retardant, polydimethylsiloxane functionalized with at least three Si-H groups, and the remaining portion of hollow ceramic particles are blended to form Part B composition. Parts A and B are then combined and mixed, and then injected between two release film sheets to form the foamed material of the present invention.

[0010] Flame retardants are metal hydroxides, carbonates, hydroxide-carbonates, or hydrates that release CO2, water, or both when heated. Examples of flame retardants include Al(OH)3, Mg(OH)2, Ca(OH)2MgCO3·3H2O (neskehonite), Mg5(CO3)4(OH)2·4H2O (hydromagnesite), MgCa(CO3)2 (huntite), AlO(OH) (boehmite), NaHCO3, and hydrated MgSO4 (epsomite). Polyorganosiloxane foam materials contain flame retardants ranging from 1, 2, or 3 weight percent to 30, 20, or 15 weight percent, based on the weight of the foam material.

[0011] The barrier material further comprises hollow, air-filled, or inert gas-filled ceramic particles ranging from 1, 5, or 10 weight percent to 35 or 30-25 weight percent. As used herein, “ceramic” refers to crystalline or semi-crystalline inorganic oxides, nitrides, carbides, oxynitrides, or oxycarbides of metals such as aluminum (e.g., crystalline or semi-crystalline Al2O3), silicon (e.g., crystalline or semi-crystalline SiO2), or calcium (e.g., crystalline or semi-crystalline CaO), or combinations thereof. Crystallinity can be measured by X-ray powder diffraction. As used herein, the term “semi-crystalline” refers to ceramic materials having amorphous and crystalline regions. The hollow ceramic particles have average volume particle sizes ranging from 25 μm, or 50 μm, or 70 μm to 300 μm, or 200 μm, or 150 μm, as measured using a dynamic light scattering analyzer such as a Beckman Coulter LS 130 Particle Size Analyzer. The resulting barrier material has a density of 0.10 or 0.15 g / cm³. 3 From 0.90 or 0.50 g / cm³ 3 It has a density in the range up to [a certain value].

[0012] In another embodiment, the present invention is a composition comprising, based on the weight of the composition, a) 2 to 50 weight percent of a polysiloxane functionalized with at least two Si-H groups and having a degree of polymerization in the range of 5 to 1000; b) 1 to 50 weight percent of water, alcohol, diol, polyol, or a compound containing one or more silanol groups; c) 10 to 90 weight percent of a polysiloxane functionalized with at least one ethylenically unsaturated group and having a degree of polymerization in the range of 20 to 2000 (the total concentration of components a, b, and c is in the range of 35 to 95 weight percent based on the weight of the composition); d) a catalytic amount of a hydrosilylation catalyst; e) 1 to 30 weight percent of a flame retardant; and f) 1 to 35 weight percent of hollow ceramic particles having a volume-average particle size in the range of 25 μm to 300 μm.

[0013] Figure 1 shows an embodiment of the present invention. The battery module comprises a shell (20) housing an array of spatially separated battery cells (30 and 30a), and a barrier material (40) in contact with adjacent battery cells, thereby forming an insulating barrier between the battery cells (30). In this embodiment, the barrier material is positioned between adjacent battery cells (30), and in another embodiment, the barrier material covers the battery cells. The battery module may further include end plates (50) on the inner edge of the shell, which are in direct contact with the battery cells (not shown) or indirectly in contact with the battery cells via a barrier foam (30a). The barrier material may be inserted into the spaces between adjacent battery cells and between the cells and the end plates, or a foam precursor may be applied on the cells and in the spaces between the battery cells, and then cured to form the barrier material.

[0014] Examples of suitable battery cell designs include cylindrical cells, pouch cells, and prismatic cells. Particularly advantageous modules include pouch cells or prismatic cells having a pre-fabricated barrier material in the form of foam sheets that are placed between cells during assembly. In the case of cylindrical designs, a precursor foam material is typically distributed into a space separating the cylindrical cells and then cured to form a barrier material surrounding the cylindrical cells.

[0015] A battery module having the barrier material described in this specification has been found to provide desired properties of heat insulation, flame resistance, and compressibility in the heat barrier application of rechargeable batteries.

[0016] In the following examples, ViMe2SiO 1 / 2 / (CH3)3Si - O 1 / 2 / SiO 4 / 2 The M w and M n were determined by GPC using a gel permeation chromatography (GPC) column filled with divinylbenzene cross-linked polystyrene bead pore type Mixed-C (Polymer Laboratory) with a size of 5 mm in diameter. THF was used as the mobile phase, and detection was performed with a refractive index detector.

[0017] Example 1 - Preparation of a Foamed Organopolysiloxane Article Having Ceramic Particles Using a Flacktek Speed Mixer, dimethylvinylsiloxy-terminated polydimethylsiloxane (Polymer 1, 11.3 pbw) having a viscosity of about 40,000 mPas, 1) dimethylvinylsiloxy-terminated polydimethylsiloxane having a viscosity of about 1,900 mPa·s and about 0.22 wt% of Vi, and 2) a ViMe2SiO 1 / 2 :(CH3)3Si - O 1 / 2 :SiO 4 / 2 structural unit ratio of 5000, M n and M w having 21,400 of ViMe2SiO 1 / 2 / (CH3)3Si - O 1 / 2 / SiO 4 / 2The first component (Part A) was prepared by mixing together a resin and a 64:36 w / w blend (polymer-resin blend, 64.9 pbw), and Micral 855 aluminum hydroxide (15.2 pbw). The contents were stirred at 2000 rpm for 30 seconds, and then a complex of Pt(0) and divinyltetramethyldisiloxane (0.93 pbw, 0.62 wt% Pt), 1,4-butanediol (2.6 pbw), and benzyl alcohol (3.3 pbw) were added to the mixture, and the contents were stirred at 2000 rpm for 30 seconds. Finally, Elminas Spheres HCMS-W150 hollow ceramic particles (average volume particle size of 100 μm; 20 pbw) were added to the mixture, and the contents were stirred at 2000 rpm for 30 seconds.

[0018] The second composition (Part B) was similarly prepared by mixing together Polymer 1 (8.9 pbw), a polymer resin blend (51 pbw), and Hymod M855 aluminum hydroxide (26.4 pbw). The contents were stirred at 2000 rpm for 30 seconds, and then a linear organohydrogenpolysiloxane having a viscosity of 30 mPa·s and a SiH content of 1.6 wt% (6.7 pbw), and a polydimethyorganohydrogensiloxane having a viscosity of 5 mPa·s and a SiH content of 0.7 wt% (5.1 pbw) were added to the mixture, and the contents were stirred at 2000 rpm for 30 seconds. Then, Elminas Spherers HCMS-W150 hollow ceramic particles (20 pbw) were added to the mixture, and the contents were stirred at 2000 rpm for 30 seconds.

[0019] Next, equal amounts of Part A and B were mixed, and the mixture was poured between two release film sheets (matte Mylar film). The initial (pre-foam) thickness was controlled to 0.045 inches using nip rollers. The sample was cured at 70 °C for 5 minutes and then at 100 °C for 15 minutes to produce a foam sheet for further testing. (Density = 0.31 g / cm 3 )

[0020] Example 2 - Preparation of a Foamed Organopolysiloxane Article with Ceramic Particles The process for preparing the foamed article of Example 1 was carried out in substantially the same manner, except that Elminas Spheres HCMS THERMO-W75 hollow ceramic particles (average volume particle size of 80 μm, 20 pbw) were used in Parts A and B. (Density = 0.31 g / cm 3 )

[0021] Example 3 - Preparation of a Foamed Organopolysiloxane Article with Ceramic Particles The process for preparing the foamed article of Example 1 was carried out in substantially the same manner, except that Elminas Spheres - W300 hollow ceramic particles (average volume particle size of 180 μm, 20 pbw) were used in Parts A and B. (Density = 0.34 g / cm 3 )

[0022] Thermal Insulation and Combustibility The foams prepared as described in the examples were tested for thermal insulation and combustibility using a hot plate placed on a hydraulic press. The hot plate was set at 600 °C and an insulator was placed on the surface. Four thermocouples (Type K) were fixed onto an aluminum heat sink (4 inches × 4 inches × 0.47 inches) using Kapton tape. Then, the sample (4 inches × 4 inches) was placed and fixed onto the heat sink using Kapton tape. An additional thermocouple (Type K) was attached to the sample surface using Kapton tape. The insulator was removed from the hot surface, and the sample attached to the heat sink was quickly placed on the hot surface with the sample surface facing the hot plate surface and the Al heat sink facing the opposite side. The pressure was rapidly increased to 355 kPa. The interface temperature between the hot plate surface and the sample surface, and the interface temperature between the sample surface and the heat sink were recorded using a data logger. When the time reached 300 seconds, the pressure was released and the test was terminated. If the temperature of the sample surface was less than 300 °C, it was considered acceptable. If there was no observable flame throughout the test, it was considered to have acceptable flame resistance.

[0023] Hardness Hardness was measured using a Shore 00 durometer. The test specimen was placed on a hard, flat surface. The indenter of the Shore 00 durometer was then pressed against the specimen, ensuring that it was parallel to the surface. The hardness was read while the indenter was firmly in contact with the specimen. A hardness of less than 80 was considered acceptable.

[0024] Compression force Compressive force was measured using a TA.HDplus texture analyzer equipped with a 100 kg load cell, a 40 mm diameter aluminum probe, and a flat heavy-duty aluminum substrate. A silicone foam sample was cut into a circle using a 1-inch diameter die cutter and placed between the substrate and the probe. The probe was initially set to the same height as the sample thickness and lowered at a rate of 1 mm / second until the pressure reached its peak. The sample thickness and pressure were recorded as a compressive force curve. The pressure at 30% of the original sample thickness was recorded. Compressive forces below 500 kPa were considered acceptable.

[0025] density of foam The foam density was calculated based on the average thickness and weight of two 1-inch diameter foam samples.

[0026] The properties of the ceramic-filled organopolysiloxane article were compared with a commercially available organopolysiloxane article (COHRlastic Silicone Foam, available from Stockwell Elastomerics) that is structurally similar to the foam in the example, except that it does not contain hollow ceramic particles.

[0027] Table 1 summarizes the performance characteristics of the foams from Examples 1-3 and a commercially available comparative foam. Density is g / cm³. 3 The measurements were taken using the following method. Hardness was measured in Shore 00 units. Compressive force (force) was measured in kPa at 30% compression. The temperature at 600°C (T after 300 seconds) refers to the surface temperature of the sample after 300 seconds, and flammability refers to the observability of the flame during the adiabatic test.

[0028] [Table 1]

[0029] Table 1 shows that the barrier material used in the battery module of the present invention passed all tests, while commercially available examples failed the thermal insulation test. Surprisingly, the barrier material having hollow ceramic particles was found to reduce the surface temperature in 300 seconds without adversely affecting other important properties of the foam. Furthermore, hollow ceramic particle sizes in the range of 50 μm to 150 μm were found to be particularly effective in reducing the surface temperature.

Claims

1. A battery module comprising a shell containing an array of spatially separated battery cells, and a barrier material in contact with adjacent battery cells, The barrier material comprises, based on the weight of the barrier material, 35 to 95 weight percent of polyorganosiloxane foam, 1 to 30 weight percent of flame retardant, and 1 to 35 weight percent of hollow ceramic particles having a volume-average particle size in the range of 25 μm to 300 μm. The barrier material is 0.10 to 0.90 g / cm³ ３ A battery module having a density in the range of [value].

2. The battery module according to claim 1, wherein the barrier material comprises 50 to 80 weight percent of the polyorganosiloxane foam and 2 to 20 weight percent of the flame retardant.

3. The flame retardant is Al(OH) ３ , Mg(OH) ２ , MgCO ３ ·3H ２ O, or Mg ５ (CO ３ ) ４ (OH) ２ ·4H ２ O, MgCa(CO ３ ) ２ , AlO(OH), NaHCO ３ , or hydrated MgSO ４ , or a combination thereof, the battery module according to claim 2.

4. The barrier material is 0.15 to 0.50 g / cm³ ３ A battery module according to any one of claims 1 to 3, having a density in the range of [value].

5. The battery module according to claim 4, wherein the hollow ceramic particles have an average volume particle size in the range of 25 μm to 200 μm due to dynamic light scattering.

6. The battery module according to claim 4, wherein the hollow ceramic particles have an average volume particle size in the range of 50 μm to 150 μm due to dynamic light scattering.

7. The hollow ceramic particles are crystalline or semicrystalline Al ２ O ３ Particles, crystalline or semi-crystalline SiO ２ The battery module according to claim 5, wherein the particles are crystalline or semicrystalline CaO particles, or crystalline or semicrystalline Al / Mg / Ca silicate.

8. The battery module according to claim 1, comprising pouch or prismatic battery cells and sheets of the barrier material disposed between adjacent battery cells.

9. The battery module according to claim 1, comprising a cylindrical battery cell, wherein the barrier material surrounds the cylindrical battery cell.

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