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Why Should You Care About Heat in EV Design?

( 10/17/2019 ) Written by: Prasanna Srinivasan

When weighing their electric vehicle (EV) options, consumers often make decisions based on key performance metrics, including how far their vehicle can go on a single charge. Auto manufacturers are responding to this demand by increasing battery energy in their EVs, which results in longer ranges and, unsurprisingly, increased thermal concerns.

Heat is of concern for any EV design engineer; it degrades vehicle components, reduces battery charge rate (resulting in an increased charging time) and can even cause damage to the temperature-sensitive lithium ion batteries if they overheat. As auto OEMs race to release longer range EVs, a similar race is being held to develop increasingly effective thermal management designs and solutions to combat rising temperatures within the drive train. Controlling and reducing the temperature of electric components has drastic and measurable results: the rule-of-thumb is that every 10-degree-Celcius reduction in temperature effectively doubles a component’s life.

In the past, thermal management has primarily been used for microelectronics. This has led many in this market to take their existing gap filler technology and scale it up for use in vehicles. However, using decades of experience of working in the automobile industry and with the input from automakers, LORD has developed gap filler solutions designed specifically for large-volume applications like EVs. The next wave of thermal interface materials (TIM) for the EV industry is heavily swayed towards liquid dispensed gap fillers.

Gap fillers have a lower interfacial resistance and can be applied in whatever pattern to fit any design change. The thermal performance of the gap filler is also independent of the part tolerances. The image below illustrates the lack of microscopic conformability of solid thermal pads (left) relative to liquid-dispense gap fillers (right).

Surface roughness between two contacting surfaces (for example, between a battery cell or module and the cooling plate) leads to only a small fraction of the apparent surfaces coming in direct contact with one another, thereby entrapping air. Conformability effect would apply to assembled battery modules, in that gap fillers would more easily fill in gaps between the cells and the cooling plate that result from manufacturing tolerances. The effect of variable bond line thickness on the conformability of thermal pads (left) versus liquid-dispense gap fillers (right) can be seen in the illustration below.

Tolerance of manufactured parts is specified our customers, with tighter tolerance leading to more costly modules and packs. With large form battery packs, the tolerance from uneven metal surfaces due to welding or fixturing, as well as stack-up tolerances in making the modules, can create a large variance in the volume that needs to be occupied by the TIM.

While EVs are still a relatively new technology (compared to internal combustion engine), manufacturers are starting to look at thermal management materials and their benefits when trying to meet the needs of the end user. However, unlike conventional gasoline-fueled vehicles, controlling the heat of an EV’s components with thermal management solutions is critical to the efficiency, durability and even safety of the vehicle. Thermal management solutions are being used more widely in automotive electronics at the chip level, battery packs, charging systems and other power electronics. As new generations of EVs are rolled out, automakers are realizing the importance of thermal management, particularly in the models touting higher-range capabilities or fast charging

The EV industry is rapidly growing and improving, but one constant remains: the need to combat overheating. Thermal management solutions such as gap fillers can help EV designers and automakers beat the heat, enabling the peak performance that EV consumers expect.

Our engineers are available to assist you in finding the best cost-targeted solution for your thermal management needs, helping optimize your process and improve performance. Have questions? Let’s talk.

ABOUT THE AUTHOR MORE BY THIS AUTHOR
Prasanna Srinivasan

Prasanna Srinivasan is Manager, Business Development & Marketing at LORD Corporation, with a focus on growing the company’s thermal management business.

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