Thermal conductivity and diffusivity of two imidazolium ionic liquids([C6mIm][BF4] and [C4mIm][BF4]) were measured by self-built hot wire method instrument. Heat capacity was calculated according to an equation of thermal conductivity
thermal diffusivity and density. The results show that the thermal conductivities of two ionic liquids have weak relation with temperature. Thermal diffusivities of two ionic liquids are very close. Thermal diffusivity changes with the increasing temperature noticeably. According to the analysis of the change of diffusivity in the micro-perspective mechanism
the momentum distribution of ions in ionic liquids has strong relation with temperature and thus affects the change of diffusivity.