Kinetics and transport processes in aqueous polysulfide-electrode reactions

Thesis/Dissertation · Wed Jan 01 04:00:00 EST 1986

OSTI ID:7162532

Lessner, P M

The objectives of this research are to obtain information on the electrochemical and chemical reactions of the aqueous sulfide/polysulfide redox couple and to use that information to design a stable and efficient redox electrode. The kinetics of the aqueous polysulfide redox couple were investigated using a transient potential step technique in a solution 1M in S/sup 0/ and 1.3M in total S/sup 2 -/, at pH 12. The steady-state current density-overpotential relationships for cobalt and platinum rotating-disk electrodes were determined for a range of temperatures. A model was developed to take into account the chemical and electrochemical reaction rates. The addition of 13 mole-% DMF to the aqueous polysulfide solution was found to significantly increase the current density, at a given temperature and overpotential, by increasing the equilibrium concentration of S/sub 2//sup -/. A flow cell for testing flow-through porous electrodes was constructed and operated. The effect of electrode material, temperature, flow rate, and the addition of DMF on electrode performance was studied. MoS/sub 2/, Co, and Ni were used as electrocatalyst materials. Raising the temperature and/or the addition of DMF had much larger effects than an order of magnitude increase in the flow rate.

• Research Organization: California Univ., Berkeley (USA)
• OSTI ID: 7162532
• Country of Publication: United States
• Language: English

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