Battery module with polyorganosiloxane foam barrier

Abstract

A battery module is disclosed that includes an array of spatially separated battery cells and a barrier material in contact with adjacent battery cells. The barrier material, which includes a polyorganosiloxane foam, a flame retardant, and expanded perlite, provides flame resistance, compressibility, and thermal insulation.

Description

[Technical Field]

[0001] The present invention relates to battery modules insulated with treated polyorganosiloxane foam barriers.

[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 have desirable properties, such as high energy density and stability, safety concerns currently limit their practical use. First, LiB cell failure can be caused by manufacturing defects, internal short circuits, overheating, overcharging, or mechanical shock. Second, heat generated from a failed cell can propagate, potentially causing thermal runaway in adjacent cells. The rapid pressure buildup resulting from these thermal events increases the risk of fire and explosion.

[0003] Thermal runaway can be mitigated by placing a thermal barrier between cells in a LiB module that provides thermal insulation and flame resistance. Commonly used thermal barriers, such as aerogel, ceramic fiber, and mica board, offer such properties, but aerogel and ceramic fiber have poor mechanical resilience, while mica board has poor compressibility. On the other hand, silicone blown foam offers adequate compressibility and is therefore suitable for low- and medium-energy density batteries, but suffers from 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 a barrier that provides thermal insulation, flame resistance, and satisfactory compressibility. Summary of the Invention

[0004] The present invention provides 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 comprising 35 to 95 weight percent of a polyorganosiloxane foam, 1 to 30 weight percent of a flame retardant, and 1 to 15 weight percent of expanded perlite, based on the weight of the barrier material, and the barrier material has a density of 0.10 to 0.90 g / cm. 3 The present invention addresses a need in the art by providing a battery module having a density in the range of

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

[0006] [Figure 1] FIG. 1 is a diagram of a battery module including polyorganosiloxane foam material. DETAILED DESCRIPTION OF THE INVENTION

[0007] The present invention provides 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 comprising 35 to 95 weight percent of a polyorganosiloxane foam, 1 to 30 weight percent of a flame retardant, and 1 to 15 weight percent of expanded perlite, based on the weight of the barrier material, and the barrier material has a density of 0.10 to 0.90 g / cm 3 The battery module has a density in the range of

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

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

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

[0011] The barrier material further comprises from 1 or 2 weight percent to 15 or 10 weight percent expanded perlite. Expanded perlite can be formed by rapidly heating perlite ore to temperatures ranging from 750°C to 1000°C. The resulting expanded particles generally have a density of 0.03 to 0.20 g / cm. 3 The dry bulk density ranges from 0.1 μm to 1000 μm. The average volume particle size typically ranges from 0.1 μm to 1000 μm using a dynamic light scattering analyzer such as a Beckman Coulter LS 130 particle size analyzer.

[0012] The resulting barrier material had a density of 0.10 g / cm 3 or 0.15 g / cm 3 to 0.90 g / cm 3 or 0.50 g / cm 3 It has a density ranging from

[0013] In another aspect, the 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, an alcohol, a diol, a 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, wherein 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 expanded perlite.

[0014] FIG. 1 illustrates an embodiment of the present invention. The battery module includes a shell (20) containing an array of spatially separated battery cells (30 and 30a) and a barrier material (40) that contacts adjacent battery cells (30), thereby forming an insulating barrier between the battery cells (30). In this embodiment, the barrier material is disposed between adjacent battery cells (30); 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 that are in direct contact with the battery cells (not shown) or indirect contact with the battery cells via the barrier foam (30a). The barrier material can be inserted into the spaces between adjacent battery cells and between the cells and the end plates, or a foam precursor can be applied over the cells and into the spaces between the battery cells and then cured to form the barrier material.

[0015] Examples of suitable battery cell designs include cylindrical cells, pouch cells, and prismatic cells. Particularly advantageous modules include pouch cells or prismatic cells with prefabricated barrier material in the form of a foam sheet that is placed between the cells during assembly. In the case of cylindrical designs, a precursor foam material is typically dispensed into the spaces separating the cylindrical cells and then cured to form the barrier material surrounding the cylindrical cells.

[0016] Battery modules having the barrier materials described herein have been found to provide the desired properties of thermal insulation, flame resistance, and compressibility in rechargeable battery thermal barrier applications.

[0017] In the following examples, ViMe2SiO 1 / 2 / (CH3)3Si-O 1 / 2 / SiO 4 / 2 Resin M w and M n was determined by gel permeation chromatography (GPC) using a GPC column packed with 5 mm diameter divinylbenzene cross-linked polystyrene beads, pore type Mixed-C (Polymer Laboratory). Tetrahydrofuran was used as the mobile phase, and detection was performed with a refractive index detector.

[0018] In the following examples, ViMe2SiO 1 / 2 / (CH3)3Si-O 1 / 2 / SiO 4 / 2 Resin M w and M n was determined by gel permeation chromatography using a GPC column packed with 5 mm diameter divinylbenzene cross-linked polystyrene beads, pore type Mixed-C (Polymer Laboratory). THF was used as the mobile phase, and detection was performed with a refractive index detector. [Example]

[0019] Example 1 - Preparation of a Foamed Organopolysiloxane Article with Expanded Perlite Particles Using a Flacktek Speed Mixer, a mixture of 1) a dimethylvinylsiloxy end-capped polydimethylsiloxane (Polymer 1, 11.0 pbw) having a viscosity of about 40,000 mPa·s and about 0.22 wt% Vi and 2) a 5:40:55 ViMe2SiO 1 / 2 :(CH3)3Si-O 1 / 2 :SiO 4 / 2 Structural unit ratio: 5000 m n, and 21,400 M w ViMe2SiO with 1 / 2 / (CH3)3Si-O 1 / 2 / SiO 4 / 2 A first composition (Part A) was prepared by mixing together a 64:36 (w / w) blend of PEG-1000 and Micral 855 aluminum hydroxide (14.7 pbw) with a polymer-resin blend (polymer-resin blend, 62.9 pbw). The contents were stirred at 2000 rpm for 30 seconds, after which Pt(0) divinyltetramethyldisiloxane complex (0.9 pbw, 0.62 wt% Pt), 1,4-butanediol (2.5 pbw), and benzyl alcohol (3.2 pbw) were added to the mixture, and the contents were stirred at 2000 rpm for 30 seconds. Finally, Omyasphere TP-312 FQ expanded perlite particles (63 μm average volume average particle size; 4.8 pbw) were added to the mixture, and the contents were stirred at 2000 rpm for 30 seconds.

[0020] A second composition (Part B) was similarly prepared by mixing together Polymer 1 (8.6 pbw), polymer resin blend (49.5 pbw), and Hymod M855 aluminum hydroxide (25.6 pbw). The contents were stirred at 2000 rpm for 30 seconds, after which a linear organohydrogenpolysiloxane (6.5 pbw) with a viscosity of 30 mPa·s and a SiH content of 1.6 wt% and a polydimethylorganohydrogensiloxane (4.9 pbw) with a viscosity of 5 mPa·s and a SiH content of 0.7 wt% were added to the mixture, and the contents were stirred at 2000 rpm for 30 seconds. Omyasphere TP-312 FQ expanded perlite particles (63 μm average volume average particle size, 4.8 pbw) were then added to the mixture, and the contents were stirred at 2000 rpm for 30 seconds.

[0021] Equal amounts of Parts A and B were then mixed and the mixture was poured between two release film sheets (matte Mylar). The initial (pre-foaming) thickness was controlled at 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 (density = 0.29 g / cm) for further testing. 3 ).

[0022] Example 2 - Preparation of a foamed organopolysiloxane article with expanded perlite particles Substantially the same process was followed to prepare the foam article of Example 1, except that Omyasphere 235 T-FQ expanded perlite particles (124 μm average volume average particle size, 4.8 pbw) were used in parts A and B (density=0.31 g / cm). 3 ).

[0023] Example 3 - Preparation of a foamed organopolysiloxane article with expanded perlite particles Substantially the same process was followed to prepare the foam article of Example 1, except that Omyasphere 235 T-FQ expanded perlite particles (9.1 pbw) were used in parts A and B (density = 0.35 g / cm 3 ).

[0024] Comparative Example 2 - Preparation of a Foamed Organopolysiloxane Article with Hollow Glass Beads Substantially the same process was followed to prepare the foam article of Example 1, except that 3M iM16K hollow glass beads (20 μm average volume average particle size, 20 pbw) were used in parts A and B (density=0.28 g / cm 3 The amount of beads was chosen to give a filler volume similar to that of the expanded perlite in Example 1.

[0025] Heat insulation and flammability The foams prepared as described in the examples were tested for thermal insulation and flammability using a hot plate mounted on a hydraulic press. The hot plate was set to 600°C, and the insulator was placed on the surface. Four thermocouples (Type K) were secured to an aluminum heat sink (4" x 4" x 0.47") using Kapton tape. The sample (4" x 4") was then placed and secured to 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 heat sink-mounted sample was quickly placed on the hot surface with the sample surface facing the hot plate surface and the Al heat sink facing away from it. The pressure was rapidly increased to 355 kPa. The interface temperatures between the hot plate surface and the sample surface, and between the sample surface and the heat sink, were recorded using a data logger. After the time reached 300 seconds, the pressure was released and the test was terminated. Sample surface temperatures below 300°C were considered acceptable. No observable flame throughout the test is deemed to be acceptable flame resistance.

[0026] hardness Hardness was measured using a Shore 00 durometer. The test specimen was placed on a hard, flat surface. The Shore 00 durometer indenter was then pressed against the specimen, ensuring that the indenter was parallel to the surface. The hardness was read while in firm contact with the specimen. A hardness of less than 80 was considered acceptable.

[0027] Compression force Compression 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 cut and placed between the substrate and the probe. The probe was initially positioned at the same height as the sample thickness and lowered at a rate of 1 mm / s until the pressure reached its maximum point. The sample thickness and pressure were recorded as a compression force curve. The pressure at 30% of the original sample thickness was recorded. A compression force of less than 500 kPa was considered acceptable.

[0028] Foam Density Foam density was calculated based on the average thickness and weight of two 1-inch diameter foam samples.

[0029] The properties of the expanded perlite-filled organopolysiloxane article were compared with two other foams: Comparative Example 1, a commercially available organopolysiloxane article (COHRlastic silicone foam available from Stockwell Elastomerics) that was similar in construction to the example foam except that it did not contain expanded perlite, and Comparative Example 2, a foam containing 3M Glass Bubbles iM16K hollow glass microspheres.

[0030] Table 1 summarizes the performance properties of the foams of Examples 1-3, a commercially available comparison foam, and a foam containing hollow glass microspheres. Density is in g / cm 3 Hardness was measured in Shore 00 units. Compression force (Force) was measured in kPa at 30% compression. Temperature at 600°C (T after 300 seconds) refers to the sample surface temperature after 300 seconds, and flammability refers to the observability of a flame during the insulation test.

[0031] TP-312-FQ refers to Omyasphere TP-312-FQ expanded perlite, 235T-FQ refers to Omyasphere 235-T-FQ expanded perlite, and iM16K refers to 3M Glass Bubbles iM16K hollow glass microspheres.

[0032] [Table 1]

[0033] Table 1 shows that the expanded perlite-containing foams of the present invention pass all tests, while the sample without expanded perlite (Comparative Example 1) fails the thermal insulation test and the sample containing hollow glass microsphere filler (Comparative Example 2) fails the compressive force test.

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 comprising 35 to 95 weight percent polyorganosiloxane foam, 1 to 30 weight percent flame retardant, and 1 to 15 weight percent expanded perlite, based on the weight of the barrier material, and the barrier material has a density of 0.10 to 0.90 g / cm ３ The battery module has a density in the range of

2. 2. The battery module of claim 1, wherein the barrier material comprises 50 to 80 weight percent of the polyorganosiloxane foam, 2 to 20 weight percent of the flame retardant, and 2 to 10 weight percent of expanded perlite, based on the weight of the barrier material.

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 3. The battery module according to claim 2, wherein the battery module is a battery having a first polarity and a second polarity.

4. The barrier material has a density of 0.15 to 0.50 g / cm ３ The battery module according to any one of claims 1 to 3, having a density in the range of

5. 5. The battery module of claim 1, comprising pouch or prismatic battery cells and a sheet of the barrier material disposed between adjacent battery cells.

6. The battery module of any one of claims 1 to 4, comprising cylindrical battery cells, the barrier material surrounding the cylindrical battery cells.

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