Within a year, announced investments in U.S. electric vehicle manufacturing have tripled from $24 billion to $73 billion (2022 Atlas Public Policy Research).
Thanks to the increase in EV production and sales, there is a growing demand for faster, more consistent, automated bonding solutions within EV batteries.
Over time, more and more customers approach Strouse with designs for EV battery components needing rapid prototyping. Working with them early on allows us to assist with the design and material selection to achieve the highest levels of project manufacturability.
As we review the ways EV batteries are used in adhesives and the best adhesives to use, you’ll develop an in-depth understanding of what your design might look like with the right materials and how you plan to manufacture it.
Why do EV Batteries Contain Adhesives?
EV battery adhesives connect the individual components while serving other roles like electrical insulation or conductors.
These adhesives join individual battery cells, assemble battery modules, fix modules into packs, and act as electrical conduits between different sections.
CELL-TO-CELL BONDING
EV batteries are often made of cells bound into battery modules, then packs, and linked to form a power structure.
The structural stability of an EV battery depends on its many adhesive connections. It’s crucial that the internal cells remain fixed together and that the battery modules are lodged together in their respective packs.
The layered structure of an EV battery creates a necessity for adhesives to bind together the cells, modules, packs, and other facets of the battery’s design. These cell-to-cell attachments require bonds to hold the different layers together.
FLEXIBLE BUSBARS
Busbars are metal strips or bars used to carry electrical current. Within EV batteries, flexible busbars can conduct higher voltages between the electrical cells to create a unified power stream throughout the battery packs.
Dielectric insulators hold up a busbar which can contain multiple layers of circuit paths. Using double-sided dielectric adhesive, EV battery manufacturers attach flexible busbars to individual cells.
Dielectric adhesive joins the flexible busbar (typically made of copper, brass, or aluminum) with the outside of the battery cell to ensure the flow of electricity is occurring as it should between cells.
INSULATION OF ELECTRICAL COMPONENTS
While there are places within a battery where you’d want an electrical current to flow, there are also spots you’d wish to insulate for safety reasons.
Building a strong electrical current between cells within any EV battery is essential, but insulating module walls can help prevent flame runaway from causing catastrophic failure.
There are many insulating materials you can choose to protect EV batteries from overheating, and the following material categories will demonstrate the different ways to insulate your batteries.
Which Adhesives are Best for EV Batteries?
The best materials for an EV battery are the ones that fit your battery’s design.
Due to the different constructions of EV batteries, it’s challenging to name materials that fit every electric vehicle. By sorting the materials based on the purposes previously discussed, you can narrow down lists of adhesives to fit your application.
The following adhesives are used in EV batteries for solutions involving thermal runaway, electrical conductivity, and adhesive bonding.
1. FLAME RETARDANT TAPES
Contrary to what you might know, flame retardant tapes aren’t immune to fire. However, rather than allowing flames to spread and cause more damage to the surrounding components, these tapes can contain a flame when ignited.
Thermal runaway is the primary cause of the sudden battery fires that affect some electric vehicles, and it’s a chain reaction that originates from an overheated or otherwise damaged battery cell that breaks down the battery pack and spreads throughout the EV battery.
The interconnected nature of EV batteries has made thermal runaway an ongoing issue, and the fire-containment function of flame retardant tapes has turned them into a crucial piece of advancing EV battery design.
2. DIELECTRIC TAPES
Stray electrical charges can pose a severe problem when they risk escaping the main body of the battery and reaching the other systems in an electric vehicle.
To reduce the likelihood of electrical charges fleeing the confines of the battery walls, manufacturers often line the body of an EV battery with dielectric tape. The dielectric tape stops electrical currents from flowing to the module or battery pack’s edges, which prevents overheating and other electrical issues.
Single or double sided dielectric tapes can be used in order to ensure EV battery safety while joining the different internal components.
3. STRUCTURAL BONDING ADHESIVES
While the other adhesives are critical to the process, it’s equally important to have adhesives whose sole purpose is to hold together the different components within the EV battery.
Structural bonding adhesives come in various thicknesses and adhesive strengths depending on the application, and many are heat-resistant. They can offer a supportive cushion or backbone to inner cells and modules with enough adhesive strength to firmly lodge them in place. Even among structural bonding adhesives, there are different types based on the location within the battery.
Lastly, unlike liquid adhesives, they provide enough gap-filling and shock absorption while holding the components in place.
What Materials Should I Use for My EV Batteries?
As the industry progresses rapidly, so does the innovation of different materials. Ultimately, the best adhesives for your EV battery will depend on your design’s purpose.
Ask yourself, which part of the EV battery am I constructing, and what’s the primary function of the material?
Having an answer will make it far easier to narrow down your material options. In addition, this will prepare you for the questions a converter will ask about your project to understand your process and confirm that they can cut your chosen material to the specifications you need.
Before moving into full-production, make sure to test prototypes of your design to ensure it’s compatible with other EV components:
Deciding upon the right materials is an essential part of your design phase, and you’ll want to discuss your material choice with your converter to ensure you build components that are optimized to function side-by-side.
