Charge storage properties of single wall carbon nanotubes/Prussian blue nanocube composites studied by multi-scale coupled electrogravimetric methods

Abstract

The gravimetric and dynamic aspects of the ions transfer at SWCNT/Prussian blue (PB) composite film electrode/electrolyte interface was investigated by the electrogravimetric impedance which couples fast quartz crystal microbalance (QCM) and electrochemical impedance spectroscopy (EIS). In contact with an aqueous KCl electrolyte, evidence was found that the kinetic of species is controlled by Faraday and capacitive electrochemical charge storage mechanisms. It was found that the interfacial transfer of K + was faster than the Cltransfer in the studied potential window. Through our electrogravimetric method of investigation, it was revealed that both adsorption/desorption and the insertion/expulsion phenomena can occur for K + , while only adsorption/desorption can occur for Cl -. Indeed, for pure PB films, the anion contribution to the charge compensation process has never been observed in the studied medium and for that, it is related to only electroadsorption on the SWCNT part of the film. Present work higlighted tha fact that electrogravimetric response of the SWCNT/PB composite electrode encloses several species contribution probably due to a synergic effect of the two phases and our study contributes to disentagling it both gravimetrically and dynamically.

Poly(ortho-phenylenediamine) overlaid fibrous carbon networks exhibiting a synergistic effect for enhanced performance in hybrid micro energy storage devices

“…where m is the total mass loading of the electrodes, v is the scan rate, E 1 and E 2 are the low and high end potentials, and I(E) depicts the response in current. The C s values are quite moderate when the SWCNT content is high which is due to the dominant capacitive response of SWCNT (typically ~ 20 F.g -1 , 55,56 ) over faradaic contribution of the PoPD. An increase in the PoPD content in the SWCNT/PoPD nanocomposite (from 3:1; 1:2; 1:4; 1:5 mass ratio and from 25 to 83 wt %) leads to an increase in the C s values (Figure 2b).…”

Ion Dynamics at the Single Wall Carbon Nanotube Based Composite Electrode/Electrolyte Interface: Influence of the Cation Size and Electrolyte pH

“…Carbon nanotubes have been extensively studied as carbon materials for the electrochemical storage of energy in capacitors due to their particular characteristics such as high electrical conductivity, unique pore structure, chemical reactivity, and their surface area where the charges are continuously distributed. , However, the investigation of the charging mechanisms, i.e., ion dynamics at the interfaces, is experimentally difficult because there are not many suitable electrochemical or physicochemical methods that allow a direct access to such information. Electrochemical quartz crystal microbalance (EQCM) has been used in previous studies employing carbon based materials, because it provides substantial information concerning the mass changes of the electrodes during charging/discharging. − The basic interpretation of the EQCM is that the mass changes of an electrode deposited on the gold electrode of a quartz resonator, Δ m , are related to changes in the resonance frequency of the quartz crystal, Δ f m , by means of the Sauerbrey equation (eq ): where ρ q is the quartz density (2.648 g·cm –3 ), μ q is the shear modulus of a shear AT quartz crystal (2.947 × 10 11 g cm –1 s –2 ), f 0 is the fundamental resonant frequency of the quartz (Hz), S is the active surface on the quartz corresponding to the metal electrode deposited on it (cm 2 ), n is the overtone number, and k s is the theoretical sensitivity factor (Hz g –1 cm 2 ).…”

Single Wall Carbon Nanotubes/Polypyrrole Composite Thin Film Electrodes: Investigation of Interfacial Ion Exchange Behavior

“…Indeed, the information provided by the classical EQCM is insufficient for a thorough explanation of the transfer mechanism of the different species. As Ac-electrogravimetry was proven to be a strong complementary tool to EQCM in the previous CNT studies [32][33][34], the composite films were also analyzed with this technique. As mentioned earlier, this coupled tool can deliver unique species-selective and frequency-dependent information about the ion exchange mechanisms at the electrode/electrolyte interface.…”

“…For this purpose, various sophisticated analytical techniques have been developed to survey electrode-electrolyte interfaces that mainly govern the electrochemical operation of energy devices. Among them, the electrochemical quartz crystal microbalance (EQCM) [32][33][34][35][36] provides gravimetric changes of electrodes during electrochemical characterizations (such as charge/discharge) and offers valuable insights of the interfaces, once the required conditions of the deposited film in terms of viscoelastic and hydrodynamic properties are included [37][38][39].…”