Advanced analytical techniques to characterize materials for electrochemical capacitors

This review covers recent developments in advanced analytical techniques to characterize materials for electrochemical capacitors. For double layer capacitors, examples of the use of in situ X-ray photoelectron spectroscopy (XPS), pulsed electrochemical mass spectrometry (PEMS) technique, temperature-programmed desorption coupled with mass spectroscopy (TPD-MS) technique, in situ NMR spectroscopy, and in situ dilatometry measurement are presented, for studying carbon/electrolyte interface with a focus onto electrolyte ions confinement in nanopores and changes during ageing. For the pseudocapacitive system, in situ X-ray (neutron) diffraction or scattering, in situ dilatometry technique, cavity micro-electrode, in situ Raman spectroscopy, TPD-MS technique, and electrochemical quartz crystal microbalance (EQCM) technique have been employed for studying materials structure, electrochemical kinetic, interface interaction, and ions adsorption/desorption. These advanced analytical techniques probe insight into charge storage mechanisms, and guiding the fast development of supercapacitors.