US-12620660-B2 - Battery assembly, ceramifiable composition, and method of making the same

Abstract

A battery assembly comprises an assembly housing, a plurality of battery modules disposed within the assembly housing and electrically coupled to a busbar, and at least one ceramifiable pad disposed within the assembly housing. Each battery module comprises a plurality of individual cells disposed within a module housing. The at least one ceramifiable pad is disposed between at least one of: at least two of the individual cells, at least two of the battery modules, the busbar and the assembly housing, or at least one of the battery modules and the assembly housing. The ceramifiable pad comprises a ceramifiable composition. Heating the ceramifiable composition to a temperature between 600 and 1600° C., inclusive, results in a ceramified composition. Ceramifiable compositions and methods of making them are also disclosed.

Inventors

• Junkang Jacob Liu
• Pingfan Wu
• Jose Maria Benito
• Walter R. Romanko
• Lianzhou Chen

Assignees

• 3M INNOVATIVE PROPERTIES COMPANY

Dates

Publication Date

20260505

Application Date

20230308

Claims (19)

1. 1 . A battery assembly comprising: an assembly housing; a plurality of battery modules disposed within the assembly housing and electrically coupled to a busbar wherein each battery module respectively comprises a plurality of individual cells disposed within a module housing; and at least one ceramifiable pad disposed within the assembly housing and disposed between at least one of: at least two of the individual cells, at least two of the battery modules, the busbar and the assembly housing, or at least one of the battery modules and the assembly housing, wherein the ceramifiable pad comprises a ceramifiable composition comprising a crosslinked silicone matrix comprising stabilizing components, wherein the stabilizing components comprise subcomponents: a) at least one of an aluminosilicate clay; b) at least one of phosphorus pentoxide, a polyphosphate, an inorganic phosphate salt, boron oxide, a hydrate thereof, a salt thereof, an organotitanate compound, or an organotin compound; and c) comprises at least one of alumina or an at least partially hydrated form thereof, calcium oxide or an at least partially hydrated form thereof, calcium carbonate, magnesium oxide or an at least partially hydrated form thereof, magnesium carbonate, or iron oxide or an at least partially hydrated form thereof; and wherein heating the ceramifiable composition to a temperature between 60° and 1600° C. inclusive, results in a ceramified composition.
2. 2 . The battery assembly of claim 1 , wherein the ceramifiable composition comprises less than 50 percent by weight of the silicone matrix, and wherein the ceramified composition comprises at least 50 percent of ceramic crystalline phase.
3. 3 . The battery assembly of claim 1 , wherein subcomponents b) and c) melt at a temperature of 600 degrees or less.
4. 4 . The battery assembly of claim 1 , wherein subcomponents a), b), and c) collectively comprise 30 to 80 percent of the ceramifiable composition.
5. 5 . The battery assembly of claim 1 , wherein subcomponent a) comprises from 45 to 60 weight percent of a), b), and c) combined.
6. 6 . The battery assembly of claim 1 , wherein subcomponent b) comprises from 5 to 40 weight percent of subcomponents a), b), and c) combined.
7. 7 . The battery assembly of claim 1 , wherein subcomponent c) comprises from 5 to 40 weight percent of subcomponents a), b), and c) combined.
8. 8 . The battery assembly of claim 1 , wherein subcomponent a) comprises halloysite.
9. 9 . The battery assembly of claim 1 , wherein subcomponent b) comprises at least one of phosphorus pentoxide, a polyphosphate, or an inorganic phosphate salt.
10. 10 . The battery assembly of claim 1 , wherein subcomponent b) comprises phosphorus pentoxide.
11. 11 . The battery assembly of claim 1 , wherein subcomponent c) comprises magnesium oxide or magnesium hydroxide.
12. 12 . The battery assembly of claim 1 , wherein subcomponent c) comprises magnesium hydroxide.
13. 13 . The battery assembly of claim 1 , wherein the ceramifiable composition further comprises at least one of hollow glass microsphere or hollow ceramic microspheres.
14. 14 . The battery assembly of claim 1 , wherein the crosslinked silicone matrix is crosslinked at least in part by exposure to high energy radiation.
15. 15 . The battery assembly of claim 14 , wherein the high energy radiation is electron beam radiation.
16. 16 . The battery assembly of claim 1 , wherein the ceramified composition contains less than or equal to 5 weight percent of organic carbon.
17. 17 . The battery assembly of claim 1 , wherein the ceramifiable pad comprises first and second opposed major surfaces, further comprising an adhesive layer disposed on the first major surface.
18. 18 . The battery assembly of claim 17 , wherein the adhesive layer comprises a silicone-based pressure-sensitive adhesive.
19. 19 . The battery assembly of claim 1 , wherein the ceramifiable composition has a percent elongation at break according to ASTM test method D638-14 (2015) of at least 30 percent and/or the ceramified composition has a compressive strength according to ASTM test method C1424-15 (2015) of at least 5 kilopascals.

Description

CROSS REFERENCE TO RELATED APPLICATIONS This application claims priority from U.S. Provisional Application Ser. No. 63/341,273, filed May 12, 2022, the disclosure of which is incorporated by reference in its/their entirety herein. BACKGROUND With the benefits of reduced emissions and fuel cost savings, electric vehicle drivetrains are rapidly displacing traditional internal combustion engines in the transportation sector. As these technologies are developed and scaled up, use of rechargeable batteries to power these drivetrains has greatly expanded, with some battery assemblies containing thousands of individual cells. The evolution of this technology has raised technical challenges around managing risks associated with these high voltage and high current devices in automotive vehicles. Battery assemblies are generally governed by a battery management system that ensures that a battery is working within a specified nominal range of operating and environmental factors, including charge and discharge currents, cell voltage, and temperature. Common battery assemblies operate best in a relatively narrow operating range for temperature, generally in the range of from about 15° C. to about 45° C. Outside of this range, the operation efficiency, functional safety, service life, and cycle stability of the battery assembly can be compromised. If the temperature exceeds a critical level, thermal runaway may occur. Thermal runaway typically occurs as a result of a chain reaction in individual cell(s), where temperatures exceeding 600° C. can lead to decomposition of battery components, gas formation, ignition of the cell(s), and flame propagation to neighboring cells. Such thermal runaway (which may include fire) can quickly spread across many cells in the battery assembly if built inappropriately. One of the primary causes of thermal runaway is an internal short circuit within the battery assembly. Short circuits can occur as a result of separators within the battery wearing out, melting, or damaging to the battery. To avoid this, battery assemblies contain many layers of insulation within the housing of the battery to electrically isolate electrical conductors within the battery from inadvertently contacting each other or the outside casing of the battery assembly, which is commonly made from metal. These materials also help avoid low current leakage which can induce undesirable self-discharge in the battery. Battery assemblies also include battery packaging materials securing individual cells in place, preventing individual cells from mechanical abuse caused by vibration, minor impacts, or battery expansion during charge and discharge. SUMMARY It would be desirable to have new materials that can function as a cushioning/damping packaging material under normal operating conditions and also as a thermal/flame barrier isolating affected cells if a thermal runaway event occurs. Advantageously, the present disclosure provides such materials in the embodiment of flexible ceramifiable materials that serve as a flexible electrical and/or thermal insulators and resilient cushioning material that may be placed under the lid, on the bottom, between modules in a battery, or even between neighboring cells in a battery. The flexible silicone-based ceramifiable compositions described herein may provide high electric resistance and high dielectric breakdown voltage at normal battery operating temperatures, but also can be converted to ceramic if subjected to extreme thermal conditions (e.g., thermal runaway), which provides excellent thermal/fire barrier protection within a battery assembly. As a further advantage, these polymeric materials can be made resiliently compressible and conformable to fill complex and irregular enclosures within a battery assembly. Overall, these beneficial properties can enable these materials to be easily installed as a resilient cushion thermal barrier isolator to mitigate the problem of battery fires and provide one way to further improve power/energy density. In a first aspect, the present disclosure provides a battery assembly comprising: an assembly housing; a plurality of battery modules disposed within the assembly housing and electrically coupled to a busbar wherein each battery module respectively comprises a plurality of individual cells disposed within a module housing; andat least one ceramifiable pad disposed within the assembly housing and disposed between at least one of: at least two of the individual cells,at least two of the battery modules,the busbar and the assembly housing, orat least one of the battery modules and the assembly housing, wherein the ceramifiable pad comprises a ceramifiable composition, and wherein heating the ceramifiable composition to a temperature between 600 and 1600° C., inclusive, results in a ceramified composition. In some embodiments, the ceramifiable composition comprises a crosslinked silicone matrix comprising silicone polymers with num