Study on the Temperature Dependence of Electrochemical Characteristics of Biowaste-Derived Activated Carbon

The electrochemical performance of activated carbons (ACs) is highly dependent on the temperature, especially under extremely cold or hot conditions. A fundamental understanding of the temperature effects on the performance of ACs is essential for a variety of applications of AC-based supercapacitors (SCs). In this work, biowaste-derived ACs are used as electrode materials in symmetrical SCs with 1 M commercial electrolyte of SBP-BF4 in PC. The electrochemical performance of the prepared ACs is systematically investigated in a temperature range of −20 °C to 60 °C. Key metrics of specific capacitance, energy and power densities, characteristic time, IR drop, and ionic diffusivity exhibit pronounced temperature dependence, highlighting strong temperature effects. Increasing the temperature leads to increases in the specific capacitance, the characteristic time, and the nominal diffusivity of electrolyte ions. The temperature dependence of the nominal diffusivity follows the Arrhenius relation with the two regimes, likely indicating a change in the behavior of ionic diffusion. The difference between the energy barrier for electrolyte-ion adsorption onto the AC surface and that for ion desorption from the AC surface increases with increasing current density.