Temperature dependences of the double layer capacitance of some solid/liquid and solid/solid electrified interfaces. An experimental study

This study investigates the influence of the temperature on the electrical double layer capacitance (C_DL) of various materials, which are essential for fuel cells and solid-state Li-ion batteries. Electrochemical impedance spectroscopy is utilized to measure the C_DL of polycrystalline Pt/aqueous electrolytes interfaces, cathode catalyst layers of polymer electrolyte membrane fuel cells (PEMFC), and Au or Li electrodes in contact with a solid-state electrolyte (SSE), a prime example for solid-state ionics. Our results show that within the investigated temperature ranges, the C_DL decreases with an increase in the temperature for Pt electrodes in an aqueous acidic electrolyte. However, for SSE and PEMFC cathode catalyst layers, the C_DL increases with temperature. The C_DL behavior with the temperature of herein presented systems is important for understanding and modeling of the interface processes for renewable energy conversion systems such as fuel cells, water electrolyzers, and batteries.