3 research outputs found
TiC-carbide derived carbon electrolyte adsorption study by ways of X-ray scattering analysis
Understanding ion adsorption in nanoporous
carbon electrodes is of great importance for designing the
next-generation of high energy density electrical doublelayer
capacitors. In this work, X-ray scattering is used for
investigating the impregnation of nanoporous carbons with
electrolytes in the absence of applied potential. We are able
to show that interactions between the carbon surface and
electrolytes allow adsorption to take place in sub-nanopores,
thus confirming experimentally for the first time the
results predicted by molecular dynamic simulations
In Situ NMR Spectroscopy of Supercapacitors: Insight into the Charge Storage Mechanism
Electrochemical capacitors, commonly known as supercapacitors, are important energy storage devices with high power capabilities and long cycle lives. Here we report the development and application of in situ nuclear magnetic resonance(NMR) methodologies to study changes at the electrodeâelectrolyte interface in working devices as they charge and discharge. For a supercapacitor comprising activated carbon electrodes and an organic electrolyte, NMR experiments carried out at different charge states allow quantification of the number of charge storing species and show that there are at least two distinct charge storage regimes. At cell voltages below 0.75 V, electrolyte anions are increasingly desorbed from the carbon micropores at the negative electrode, while at the positive electrode there is little change in the number of anions that are adsorbed as the voltage is increased. However, above a cell voltage of 0.75 V, dramatic increases in the amount of adsorbed anions in the positive electrode are observed while anions continue to be desorbed at the negative electrode. NMR experiments with simultaneous cyclic voltammetry show that supercapacitor charging causes marked changes to the local environments of charge storing species, with periodic changes of their chemical shift observed. NMR calculations on a model carbon fragment show that the addition and removal of electrons from a delocalized system should lead to considerable increases in the nucleus-independent chemical shift of nearby species, in agreement with our experimental observations
In Situ NMR Spectroscopy of Supercapacitors: Insight into the Charge Storage Mechanism
Electrochemical capacitors, commonly
known as supercapacitors,
are important energy storage devices with high power capabilities
and long cycle lives. Here we report the development and application
of in situ nuclear magnetic resonance (NMR) methodologies to study
changes at the electrodeâelectrolyte interface in working devices
as they charge and discharge. For a supercapacitor comprising activated
carbon electrodes and an organic electrolyte, NMR experiments carried
out at different charge states allow quantification of the number
of charge storing species and show that there are at least two distinct
charge storage regimes. At cell voltages below 0.75 V, electrolyte
anions are increasingly desorbed from the carbon micropores at the
negative electrode, while at the positive electrode there is little
change in the number of anions that are adsorbed as the voltage is
increased. However, above a cell voltage of 0.75 V, dramatic increases
in the amount of adsorbed anions in the positive electrode are observed
while anions continue to be desorbed at the negative electrode. NMR
experiments with simultaneous cyclic voltammetry show that supercapacitor
charging causes marked changes to the local environments of charge
storing species, with periodic changes of their chemical shift observed.
NMR calculations on a model carbon fragment show that the addition
and removal of electrons from a delocalized system should lead to
considerable increases in the nucleus-independent chemical shift of
nearby species, in agreement with our experimental observations