42 research outputs found
Combining Deep Eutectic Solvents with TEMPO‐based Polymer Electrodes: Influence of Molar Ratio on Electrode Performance
For sustainable energy storage, all-organic batteries based on redox-active polymers promise to become an alternative to lithium ion batteries. Yet, polymers contribute to the goal of an all-organic cell as electrodes or as solid electrolytes. Here, we replace the electrolyte with a deep eutectic solvent (DES) composed of sodium bis(trifluoromethanesulfonyl)imide (NaTFSI) and N-methylacetamide (NMA), while using poly(2,2,6,6-tetramethylpiperidin-1-yl-oxyl methacrylate) (PTMA) as cathode. The successful combination of a DES with a polymer electrode is reported here for the first time. The electrochemical stability of PTMA electrodes in the DES at the eutectic molar ratio of 1 : 6 is comparable to conventional battery electrolytes. More viscous electrolytes with higher salt concentration can hinder cycling at high rates. Lower salt concentration leads to decreasing capacities and faster decomposition. The eutectic mixture of 1 : 6 is best suited uniting high stability and moderate viscosity
Melting of a colloidal crystal
A melting transition for a system of hard spheres interacting by a repulsive
Yukawa potential of DLVO form is studied. To find the location of the phase
boundary, we propose a simple theory to calculate the free energies for the
coexisting liquid and solid. The free energy for the liquid phase is
approximated by a virial expansion. The free energy of the crystalline phase is
calculated in the spirit of the Lenard-Jonnes and Devonshire (LJD) theory. The
phase boundary is found by equating the pressures and chemical potentials of
the coexisting phases. When the approximation leading to the equation of state
for the liquid breakes down, the first order transition line is also obtained
by applying the Lindemann criterion to the solid phase. Our results are then
compared with the Monte Carlo simulations.Comment: 7 pages, Revtex (using twocolumn style), four figures and postscript
file. Submitted to Physica
Effective charge versus bare charge for colloids in the infinite dilution limit
We propose an analytical approximation for the dependence of the effective
charge on the bare charge for spherical and cylindrical macro-ions as a
function of the size of the colloid and salt content, for the situation of a
unique colloid immersed in a sea of electrolyte (where the definition of an
effective charge is non ambiguous).
Our approach is based on the Poisson-Boltzmann (PB) mean-field theory.
Mathematically speaking, our estimate is asymptotically exact in the limit
, where is the radius of the colloid and the
inverse screening length. In practice, a careful comparison with effective
charges parameters obtained by numerically solving the full non-linear PB
theory proves that it is good down to . This is precisely the
limit appropriate to treat colloidal suspensions. A particular emphasis is put
on the range of parameters suitable to describe both single and double strand
DNA molecules under physiological conditions.Comment: Proceedings of the International Conference on Strongly Coupled
Coulomb Systems, Santa Fe (2002
Diffusion and conduction in a salt-free colloidal suspension via molecular dynamics simulations
Molecular dynamics (MD) simulations are used to determine the diffusion
coefficients, electrophoretic mobilities and electrical conductivity of a
charged colloidal suspension in the salt-free regime as a function of the
colloid charge. The behavior of the colloidal particles' diffusion constant can
be well understood in terms of two coupled effects: counterion 'condensation'
and slowdown due to the relaxation effect. We find that the conductivity
exhibits a maximum which approximately separates the regimes of
counterion-dominated and colloid-dominated conduction. We analyze the
electrophoretic mobilities and the conductivity in terms of commonly employed
assumptions about the role of "free" and "condensed" counterions, and discuss
different interpretations of this approach.Comment: 10 pages, 4 figure
Combining Deep Eutectic Solvents with TEMPO-based Polymer Electrodes: Influence of Molar Ratio on Electrode Performance
For sustainable storage of electrical energy, all-organic batteries based on redox-active polymers promise to become an alternative to conventional lithium ion batteries. Yet, polymers can only contribute to the goal of an all-organic cell as electrodes or as solid electrolytes. Here, we replace the electrolyte with a sustainable deep eutectic solvent (DES) composed of sodium bis(trifluoromethanesulfonyl)imide (NaTFSI) and N-methylacetamide (NMA), while using poly(2,2,6,6-tetramethylpiperidin-1-yl-oxyl methacrylate) (PTMA) as cathode. The successful combination of a DES with a polymer electrode is reported here for the first time. The electrochemical stability of PTMA electrodes in the DES at the eutectic molar ratio of 1:6 is comparable to conventional battery electrolytes. More viscous electrolytes with higher salt concentrations can hinder charging and discharging at high rates. Lower salt concentrations on the other hand lead to decreasing capacities and faster decomposition. The used eutectic mixture of 1:6 is best suited uniting high stability and moderate viscosity