Student Poster Presentation #11 (Session 1)
Soret Effect on Symmetric Lithium Cells
Dr. Daniel T. Hallinan, jr., Jesufane Mentor
Department of Chemical & Biomedical Engineering, FAMU-FSU College of Engineering
Abstract
Conversion of temperature gradients to electricity could be used to yield waste heat and improve energy efficiency
across many areas. To this end, we are studying the Soret effect in a polymer electrolyte using an electrochemical
cell. Symmetric lithium cells are subjected to temperature gradients. Thermal diffusion caused by the temperature
gradient results in a concentration gradient, which in the absence of a current leads to an electrochemical potential.
The potential at steady state is used to calculate the concentration gradient. This allows the calculation of the
Soret coefficient which gives insight into the direction and magnitude of the mass flux of lithium salt in the
polymer electrolyte due to thermal diffusion. We found that the Soret coefficient is positive, which means that the
salt present in the electrolyte is diffusing from the heated part of the cell to the cooler part of the cell. With
increasing temperature gradient, there is a positive increase of potential difference. At an average temperature of
30 ᵒ C, we found that the Soret coefficient to be positive. However, in a separate study they found at a temperature
of 22ᵒ C, the Soret coefficient is only positive when the polyethylene oxide is dissolved in water 1 .
Reference
1. Kita, Rio, Simone Wiegand, and Jutta Luettmer-Strathmann. "Sign change of the Soret coefficient of poly (ethylene
oxide) in water/ethanol mixtures observed by thermal diffusion forced Rayleigh scattering." The Journal of chemical
physics 121.8 (2004): 3874-3885.
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