Materials that Improve Battery Performance

Although the utility of electric vehicles (EVs) has made substantial progress in the last ten years, there remains much work toward improving their yield and lowering costs. The nucleus of this challenge is the battery system, where designers must try and balance competing constraints such as cost, power output and weight to optimize vehicle performance. The most promising path towards a solution often lies in the battery pack arrangement, where any design iteration must consider potential penalties to thermal management, electromagnetic and radio frequency interference (EMI/RFI) susceptibility, and environmental/physical exposure. MG Chemicals boasts an expansive portfolio of material solutions that cover common challenges encountered with battery pack systems, including case studies.

Functional Adhesives for Bonding & Protection

The primary function of an adhesive is to bond two surfaces sufficiently enough to provide a functional mechanical hold. However, specialty adhesives with secondary features such as flame retardancy and thermal conductivity have added features that are of value when used in battery pack assemblies. These adhesives also improve thermal cycling stability and reduce the weight of the battery by eliminating welds.  


Structural & Thermal Adhesives

The leading battery type for EVs is the lithium-ion battery, owing mainly to its high energy density and longevity. However, a drawback of this battery is the risk of fire if the battery becomes punctured or charged improperly. To mitigate this risk, designers use flame retardant materials such as our 9200FR to build firewalls around the battery pack to prevent the spread of fire. This adhesive is a 2-part flame retardant structural epoxy that provides exceptional bond strength and is certified by Underwriter Laboratories as UL94 V-0. It is also an excellent replacement for PET films used along the cooling tray to adhere modules, whether in a cylindrical or prismatic arrangement. 

Thermal management is a critical design parameter for battery packs as individual cells comprising the modules heat up during charging, making quick and effective heat dissipation necessary. Modules are bonded together within the pack array using thermally conductive adhesives like our 8329TFF and 8349TFM that facilitates effective lateral heat transfer out of the pack, regulating the temperature. These materials bond the modules to cooling plates and can be used as gap fillers between the top of the pack and the lid, helping conduct heat away. 

Figure 1 - Layered diagram of battery pack with structural adhesive (left) and cell array with thermally conductive adhesive (right)
Figure 1: Layered diagram of battery pack with structural adhesive (left) and cell array with thermally conductive adhesive (right)


Conductive Coatings for Noise Reduction

Electrically conductive coatings are 1 or 2-part systems that incorporate conductive fillers like nickel, copper and silver, with binder systems standard in most industrial paints. These coatings are a quick and easy means to metalize plastics for two primary purposes: shielding electrical devices from EMI/RFI and fabricating conductive traces. With battery packs, designers need to shield the battery from neighbouring devices, both internal and external to the vehicle to prevent crosstalk and subsequent malfunction. Conductive coatings like our 841AR and 842AR can be applied on the interior of the battery pack lid and housing assembly to block interference from external magnetic and electric fields. These coatings allow auto manufacturers to switch from heavy metal battery casings to lightweight plastics, reducing overall weight and improving efficiency. Also, these conductive coatings reduce electrical resistance between active materials and the aluminum foil along the wall of battery cells, improving charging and discharging performance.  

Figure 2 - Conductive coating applied along battery cell wall
Figure 2: Conductive coating applied along battery cell wall


Environmental Protection

Vehicle components are exposed to a host of contaminants ranging from the fluids circulating within the vehicle to salts and other corrosive elements from the external environment. To ensure the longevity of EV batteries, coatings and resins are applied to protect sections against corrosion, physical shocks and electrical arcing. Dielectric coatings like our 4223F, 4225, 4200UV and 4226A are used for coating electrical components such as PCBAs, busbars and cold plates that are prone to failure from corrosion or electrical arcing.

Liquid resins like our 834B and 834HTC potting compounds cure to a hard rigid finish and can be used to fill gaps between cells, ensuring everything remains tightly fixed in place. The potting compounds are both thermally conductive and flame retardant, helping prevent overheating and runaway fire in the event of an ignition. 

Figure 3: Conformal coating applied on the PCB of the battery pack
Figure 3: Conformal coating applied on the PCB of the battery pack

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