Asymmetric tuning of Kapitza resistance at the ionic liquid-electrode interface via electric fields and interaction strength

The interfacial thermal behavior between graphene electrodes and ionic liquid (IL) electrolytes has gained significant attention, as it plays a crucial role in energy storage efficiency and thermal management in electric double-layer supercapacitors. In this study, we employ molecular dynamics simulations to investigate interfacial thermal transport in [BMIM][PF₆] IL confined between planar graphene electrodes, systematically exploring the interplay between interfacial binding strength and electric fields in regulating interfacial thermal resistance (ITR). Our results reveal an asymmetric modulation of ITR at the cathode and anode under applied electric field and varying interaction strength. Specifically, ITR at the cathode exhibits greater sensitivity to the electric field, while at the anode, ITR is more strongly influenced by the Lennard-Jones (LJ) interaction strength between ILs and the electrodes. A detailed structural analysis shows that the density of [BMIM]⁺ cations in the electrical double layer (EDL) near the electrodes dominates interfacial thermal transport. The flexible, ring-like structure of [BMIM]+ allows it to align parallel to the graphene electrodes, enhancing thermal transport. In contrast, the spherical [PF₆]⁻ anions interact with the electrode through limited point contacts, resulting in inefficient heat conduction. Increasing the applied potential at the cathode or enhancing the LJ interaction strength effectively increases cation density in the EDL, thereby reducing ITR at the interface. These findings provide deeper insights into interfacial heat transfer mechanisms in IL-based supercapacitors and offer valuable guidance for optimizing electrode design and thermal management in energy storage systems.