Electrochemical Control of Thermal Conduction in Thin Films

Controlling the flow of heat through materials is important for many technologies. While materials with high and low thermal conductivities are available, materials with variable and reversible thermal conductivities are rare, and other than high pressure experiments, only small reversible modulations in thermal conductivities have been reported.  We will describe our in-situ and ex-situ measurements of the electrochemical modulation of the thermal conductivity of sputtered films of Li_xCoO₂ using time-domain thermoreflectance (TDTR).  The thermal conductivity ratio between the lithiated and delithiated state can exceed 2.5. The oxidation-state dependent thermal conductivity of electrolytically active transition metal oxides provides opportunities for dynamic control of thermal conductivity and may be important for understanding the thermal management of electrochemical energy storage devices.