Effects of additives and KOH electrolyte concentration on dissolution of iron electrodes

Technical Report · Fri Jun 01 04:00:00 EDT 1984

OSTI ID:6692743

Poa, D S; Miller, J F; Yao, N P

The effects of additives (K/sub 2/S, LiOH, and FeO) and KOH concentration on electrochemical dissolution of iron electrodes in KOH electrolytes were investigated, using a rotating ring-disc electrode. Experimental results were analyzed on the basis of changes of characteristic disc and ring currents and variation of Fe(II) species supersaturation at the disc electrode surface. In 8 to 10 M KOH solutions, both the dissolution rate of iron to form soluble Fe(II) species and the irreversibility of the electrode redox processes are high. In 0.5 to 4 KOH solutions, reversibility of the electrode redox processes is better, but active dissolution of iron remains high. When the iron electrode is operated in 5 to 7.5 M KOH solutions, active dissolution to form soluble Fe(II) species is low during both charge and discharge, and the reversibility of the electrode redox processes is higher than in 8 to 10 M KOH solutions. When K/sub 2/S is added to the electrolyte, the supersaturation of soluble Fe(II) species increases sharply, the reversibility of the iron electrode redox processes appears improved, and the H/sub 2/ gas evolution overvoltage increases by 100 to 150 mV. When LiOH is added to the electrolyte, the anodic and cathodic dissolution of the iron electrode, forming soluble Fe(II) species, as well as the formation of solid film products at the electrode surface, may be significantly decreased; whereas the reversibility of the iron electrode redox processes may be increased. Saturation of the KOH electrolyte with FeO may cause significant changes in the mechanisms and reaction rates of iron dissolution, because of the competing oxidation-reduction of Fe(II) species, which become more available at the electrode surface. However, the influence of FeO saturation on the dissolution of iron in the form of soluble Fe(II) species is probably not significant.

• Research Organization: Argonne National Lab., IL (USA)
• DOE Contract Number: W-31109-ENG-38
• OSTI ID: 6692743
• Report Number(s): ANL/OEPM-84-1; ON: DE84014840
• Country of Publication: United States
• Language: English

Related Subjects

25 ENERGY STORAGE
250903* -- Energy Storage-- Batteries-- Materials
Components
& Auxiliaries
ADDITIVES
ALKALI METAL COMPOUNDS
CHALCOGENIDES
CHEMISTRY
DISSOLUTION
ELECTROCHEMICAL CELLS
ELECTROCHEMISTRY
ELECTRODES
ELECTROLYTES
ELEMENTS
HYDROGEN COMPOUNDS
HYDROXIDES
IRON
IRON COMPOUNDS
IRON OXIDES
LITHIUM COMPOUNDS
LITHIUM HYDROXIDES
METALS
OXIDES
OXYGEN COMPOUNDS
POTASSIUM COMPOUNDS
POTASSIUM HYDROXIDES
POTASSIUM SULFIDES
SULFIDES
SULFUR COMPOUNDS
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS