Electrochemical Thermoelectric Conversion with Polysulfide as Redox Species

Area of Science:

• Electrochemistry
• Materials Science
• Energy Conversion

Background:

• Thermocells offer pollution-free waste heat to electricity conversion.
• High cost and corrosivity of traditional redox species limit thermocell commercialization.

Purpose of the Study:

• To demonstrate a thermocell utilizing abundant polysulfides as redox species.
• To investigate the effect of sulfur addition on thermocell performance and electrochemistry.

Main Methods:

• Synthesis of 1-butyl-1-methylpyrrolidinium polysulfide [(P14)2S3].
• Preparation of redox species by adding sulfur to the polysulfide solution in DMSO.
• Thermoelectric measurements, including Seebeck coefficient determination.
• Operando UV/Vis spectroscopy and open-circuit voltage analysis.

Main Results:

• Successful demonstration of a thermocell using polysulfides.
• Seebeck coefficient tunable from -0.68 to +0.5 mV/K through sulfur addition.
• Identified changes in dominating redox reactions as the cause for the Seebeck coefficient shift.
• Provided thermodynamic insights into polysulfide electrochemistry.

Conclusions:

• Polysulfides are a viable, cost-effective alternative to traditional redox species in thermocells.
• Tuning redox reactions by sulfur addition enables control over thermocell performance.
• Findings are significant for developing efficient thermocells and advancing lithium-sulfur battery technology.