Electric vehicle battery gaskets provide environmental sealing and thermal insulation. They may also provide fire protection and shielding against electromagnetic interference (EMI). EV battery gaskets are made of rubbers, or elastomers, that impart specific properties, such as chemical resistance. Because rubber is compressible, these elastomeric gaskets fill the gaps between machined metal surfaces. Elasto Proxy can provide you with the EV battery gaskets that you need, so contact us to discuss your application.   

FIP Gaskets vs. Extruded Gaskets vs. Flat Gaskets

There are different ways to fabricate EV battery gaskets. Sometimes, the production volume determines the best method.

  • Form in place (FIP) gaskets are used in high-volume, automated assembly (such as the automotive industry) and require dispensing and curing.
  • Extruded rubber gaskets are used in low-to-medium volumes and for both prototypes and production. They are cut-to-length from rubber extrusions and then molded or bonded.
  • Flat gaskets are cut from sheet materials. Depending on the gasket fabrication method, they can be used for various production volumes.

FIP, extruded rubber, and flat gaskets are available in harder and softer durometers to support the proper amount of compression for a reliable seal. However, extrusions and sheets don’t require dispensing and curing. If you need extruded rubber gaskets, or gaskets cut from sheet materials, talk to Elasto Proxy. In addition to gasket fabrication, we offer value-added manufacturing services.  

Types of Electric Vehicle Battery Gaskets

There are four major types of EV battery gaskets.

  • EV battery cover gaskets
  • EV battery compartment gaskets
  • EMI shielding gaskets
  • Flame resistant gaskets

Whether they’re fabricated from extrusions or sheets, Elasto Proxy can provide you with all of them.

Electric Vehicle Battery Gaskets for Covers

EV battery covers are typically made of aluminum, a lightweight and corrosion-resistant metal. They have a large sealing area and are subjected to harsh chemicals, high temperatures, and physical stresses. Consequently, most EV battery cover gaskets are made of either silicone foams or polyurethane foams. They have hollow sections that mate with metal cover plates and fill surface discontinuities.

EV battery cover gaskets are designed to seal these gaps but can also accommodate some degree of movement within the application. That’s important because heat from the battery causes metal to expand and, conversely, cooling causes metal to contract. If a gasketing material is hard and rigid instead of soft and compressible, cracking can occur.     

During installation, the EV battery gasket may fit a groove in the battery cover or attach to a flat surface with a pressure-sensitive adhesive (PSA). These adhesives are used with tapes that have a release liner for peel-and-stick installation with light pressure. PSA adhesives provide only temporary fastening, however, so you’ll need metal fasteners for permanent joining.

Water jet cutting can create holes for the bolts or screws that support this long-term fastening. Unlike other forms of gasket cutting, water jet equipment does not require paying for tooling or waiting for it to arrive. Elasto Proxy can provide you with water jet cut gaskets, including seals with PSA tape for convenient installation and precisely cut holes for metal fasteners.

EV Battery Gaskets for Compartments

Environmental sealing and thermal insulation is also needed inside the electric vehicle’s battery compartment, where cells, modules, and packs all perform specific functions.

  • Cells are the basic units of lithium-ion (Li-ion) batteries and include a cathode, anode, separator, and electrolyte.
  • Modules are assemblies of cells that are separated by metal frames.
  • Packs consist of battery modules and include a cooling system, which can use a phase change material (FCM), fin cooling, air cooling, or liquid cooling.

The Nissan LEAF provides an example. Its battery pack has 24 modules and each module has eight cells. The gaskets must seal and insulate the entire battery module and, in turn, protect all of the battery cells.

Often, EV battery pack gaskets are made of closed-cell silicone sponge. These EV gaskets need to withstand the heat that’s produced by the battery pack, prevent the passage of gases and liquids, and dampen noise and vibration. They must also seal out water, dust, moisture, and road salt for proper ingress protection (IP). Talk to Elasto Proxy about these and other gasket design requirements.

EMI Shielding Gaskets for EV Batteries

There are different types of electric vehicles, but all of them need EMI shielding in the form of reliable gasketing. In vehicles that are all-electric, there are strong electromagnetic fields between the traction battery pack and the auxiliary battery pack and the electric traction motor, DC/DC converter, power electronics controller, and other onboard systems. Other EV types also face EMI challenges.

For example, hybrid electric vehicles (HEV), plug-in hybrid electric vehicles (PHEVs), and fuel cell electric vehicles (FCEV) are all susceptible to EMI. That’s because they contain at least an auxiliary battery along with related electronic components. In all electric vehicles (xEV), GPS receivers and safety-related sensors are susceptible to interference from the battery but depend upon uninterrupted RF signals.

There are also sources of EMI outside the EV, beginning with electric charging stations (ECS). Whether an ECS connects directly to the vehicle’s onboard charging circuitry or requires an AC-to-DC inverter, the presence of AC and DC magnetic fields can cause electromagnetic disturbances that disable onboard vehicle functions such as system monitoring.

For applications that require both environmental sealing and EMI shielding, elastomers filled with metal or metal-coated particles are used. Particle-filled silicones are an especially good choice because silicone elastomers can resist the high temperatures associated with tightly packaged electronics, including the heat from EV batteries. Silicones also resist thermal cycling and contact with water and some chemicals.

Electrically conductive silicones are supplied as sheet stock, continuous rolls, extrusions, and fabricated shapes. They are filled with electrically-conductive materials, including non-silver alternatives such as nickel-graphite and nickel-aluminum that eliminate the price volatility associated with precious metals. Many of these conductive EMI elastomers can provide shielding effectiveness up to 120dB at 10GHz.

Flame Resistant EV Battery Gaskets

UL 94 V-0, a flammability standard from Underwriters Laboratories (UL), has long been a focus for automotive safety. Today, EV battery fires are of concern because applying water to a fire can cause violent flare-ups as water molecules separate into explosive hydrogen and oxygen gases. EV gaskets need to resist flame, including fires from electrical overloads, component failure, and insulation breakdowns.

Today, there are EMI gasket materials that combine UL 94-V0 flame resistance with EMI shielding. These materials include nickel-graphite filled silicones that are supplied as either conductive sheet stock or continuous rolls. Elasto Proxy can supply you with UL 94-V0 flame resistant, EMI shielding gaskets that are made from 40-durometer or 60-duromter materials.

Electric Vehicle Battery Gaskets from Elasto Proxy

For over 30 years, Elasto Proxy has supplied the heavy equipment and transportation industries with custom rubber gaskets. As an AS 9100D and ISO 9001:2015 certified company, we’re also ready to help the aviation industry with EV sealing and insulation. So, whether you’re designing heavy trucks or electric vertical take-of and landing (eVTOL) aircraft, let’s talk about your gasket application.

At our manufacturing center near Montreal, Canada, our custom fabrication capabilities include water jet cutting, gasket bonding and molding, and gasket taping. We source rubber sheets, rolls, and extrusions made from silicones and other materials that we source from trusted suppliers. Elasto Proxy can help you with seal design and material selection, too. Plus, we have a network of strategically-located warehouses.

Contact us for more information, or to request a quote for EV battery gaskets.   

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