Figure 1: An aerogel, a lightweight material commonly used for insulation or thermal management applications
An aerogel is an extremely low density solid, where the liquid component of the gel has been replaced with a gas. Aerogels are commonly used as insulation, sorbents, and thermal interface materials (TIMs). Therefore, thermal conductivity is a critical performance attribute for understanding the behavior of aerogels.
Figure 2: Testing the thermal conductivity of an aerogel using C-Therm’s Modified Transient Plane Source (MTPS) sensor
One novel application of use in the prevention of thermal runaway in lithium ion battery packs used in electric vehicles (EV). Thermal runaway is one of the main causes of fire in EVs, as one battery cell experiences thermal runaway, the heat generated initiates the process in neighboring cells, creating a large fire hazard. When using aerogels as an interstitial material, thermal runaway propagation was delayed by 4.5 times, and when combining an aerogel insulation layer with a liquid cooling plate, the propagation was effectively blocked [1].
Another emerging application is as a thermal interface material (TIM). While traditionally insulation has been a primary use for aerogels, a novel aerogel produced by combing the properties of a fluorinated graphene aerogel (FGA) and polydimethylsiloxane (PDMS) was made in with optimized thermal conductivity [2]. The results were then compared to other aerogels and can be seen below, compared to more conventional aerogels.
Figure 3: Thermal conductivity testing results of different aerogels. Results indicate their capacity as effective thermal interface materials
The novel FGA/PDMS material was shown to have a significant increase in thermal conductivity compared to the other aerogels studied, and thus enhanced performance as a TIM. This was accomplished by freeze drying techniques that promoted the development of a tightly packed composite structure, which increased the thermal conductivity. However, this thermal conductivity was achieved while maintaining a low electrical conductivity, making it suitable for use in electronics.
Additionally, it was found that this aerogel had flame retardant properties. After being heated to 1982°C, and held there for two minutes by a blow torch, the aerogel showed no damage or deformation from this elevated temperature. This indicates that FGA/PDMS materials could be used as a flame retardant barrier to prevent fire propagation.
Figure 4: Results of exposing a novel aerogel material to high temperatures for prolonged periods of time. This shows that the aerogel underwent no noticeable damage and therefore has an application as a flame retardant material.
This webinar will feature C-Therm’s Modified Transient Plane Source (MTPS) technique for thermal conductivity measurement of aerogels. The need for thermal conductivity data will be highlighted through different applications of aerogels, including its use as an energy efficient insulation, the prevention of thermal runaway in lithium-ion cells, and its use as a thermal interface material (TIM). Aerogels made from different sources, including renewable materials will be analyzed for their differing thermal properties. Furthermore, the Rigaku Differential Scanning Calorimeter (DSC) will be featured with its unique Sample Observation technology in order to determine the specific heat capacity of aerogels.
This webinar aired on July 21, 2022 @ 2:00PM GMT-3.
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