A nano-sheet graphene-based enhanced thermal radiation composite for passive heat dissipation from vehicle batteries

Abstract

In response to thermal runaway (TR) of electric vehicles, recent attention has been focused on mitigation strategies such as efficient heat dredging in battery thermal management. Thermal management with particular focus on battery cooling has been becoming increasingly significant. TR usually happened when an electric vehicle is unpowered and charged. In this state, traditional active battery cooling schemes are disabled, which can easily lead to dangerous incidents due to loss of cooling ability, and advanced passive cooling strategies are therefore gaining importance. Herein, we developed an enhanced thermal radiation material, consisting of ∼1 ​μm thick multilayered nano-sheet graphene film coated upon the heat dissipation surface, thereby enhancing thermal radiation in the nanoscale. The surface was characterized on the nanoscale, and tested in a battery-cooling scenario. We found that the graphene-based coating's spectral emissivity is between 91 ​% and 95 ​% in the mid-infrared region, and thermal experiments consequently illustrated that graphene-based radiative cooling yielded up to 15.1 ​% temperature reduction when compared to the uncoated analogue. Using the novel graphene surface to augment a heat pipe, the temperature reduction can be further enlarged to 25.6 ​%. The new material may contribute to transportation safety, global warming mitigation and carbon neutralization.