Operando AC In-Plane Impedance Spectroscopy of Electrodes for Energy Storage Systems

Characterization of battery and supercapacitor materials and devices is typically performed using various methods such as cyclic voltammetry, electrochemical impedance spectroscopy, galvanostatic cycling, etc. However, none of these techniques allow for operando tracking of changes in the electrode material’s in-plane ionic and electronic percolation under polarization, which plays a key-role in the electrochemical performance of the material. Here, we report an experimental set-up devoted to measuring the operando in-plane AC impedance and DC resistance of porous activated carbon and Ti 3 C 2 MXene electrodes during electrochemical cycling. These impedance measurements allow for the deconvolution and tracking of the ionic and electronic contributions of the total impedance and the change in these components under polarization. Operando tracking of the in-plane electrode impedance under polarization brings insights regarding electronic and ionic transport mechanisms of electrodes during operation. This set-up serves as a complementary tool to further evaluate and improve the performance of electrode materials for energy storage.