Reactions of FeS Electrodes in LiCl ‐ KCl Electrolyte

Abstract

The reactions of FeS electrodes in LiC1-KC1 electrolytes of various compositions were determined by a combination of phase studies, cyclic voltammetry, and emf measurements. The effect of temperature, charge-cutoff voltage, and electrolyte composition on the phases present in the sulfide electrode were determined. Six electrochemical and four chemical reactions can occur. The emf's of three of the six electrochemical reactions were measured over a temperature range of 380~176 and were computed for the other three electrochemical reactions. The free energy changes for the chemical reactions were also calculated.* Electrochemical Society Active Member. Key words; fused salts, free energy, voltammetry, emf. potential of this electrode in LiCIoKC1 electrolyte at 400~ is approximately 300 mV less anodic than that of liquid lithium, and the electrode reaction is simplySome properties of the FeS electrode, which has a voltage of about 1.34V vs. Li-A1, have also been reported (9-17). Five phases have been identified: FeS, LiKsFe~4SesC1 (~J-phase), Li2FeSe (~X-phase), Li2S, and Fe. The FeS phase corresponds to a fully charged electrode, the J-and X-phases are present at intermediate states of discharge or charge, and the Fe and Lies phases correspond to the fully discharged electrode. Additional phases are formed when cells are overcharged (12). These higher voltage phases were usually avoided in the present study. ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 130.15.241.167 Downloaded on 2015-03-08 to IP VoL 128, No. 4 FeS ELECTRODES 761 ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 130.15.241.167 Downloaded on 2015-03-08 to IP ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 130.15.241.167 Downloaded on 2015-03-08 to IP VoL 12,8, No. 4 FeS ELECTRODES 767 E z u3 n... t.D ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 130.15.241.167 Downloaded on 2015-03-08 to IP

Thermal activated (thermal) battery technology

“…This value is lower than the previous values (mean value: 13.7 × 10 −4 at 450 • C) in the LiCl-KCl eutectic. It was explained by the formation of the so-call "J-phase" (LiK 6 Fe 24 S 26 Cl) at a temperature below 470 • C described later by Tomczuk et al [130] arising from the reaction between FeS 1.14 and the molten chlorides [131,132]. The solubilities of Li 2 S, FeS 2 , and FeS 1.14 follow Arrhenius-type law.…”

Thermal activated (“thermal”) battery technology

“…FeS was studied extensively by ANL for use in secondary high-temperature batteries for vehicle applications as part of the U.S. Advanced Battery Consortium (USABC) with the automobile industry [28][29][30][31][32][33]. The solubility product constant, K sp , of FeS in LiCl-KCl eutectic electrolyte was calculated to be only 2.3 × 10 −12 on an ion-fraction basis, which is very low [24].…”

Li-alloy/FeS cell design and analysis report

“…The chemistry and electrochemistry of the FeS electrode have been investigated in detail, and the results indicate that the reactions are much more complex than shown earlier for the overall cell react on. 6 , 7 The cell reactions that can be deduced from the Li-Fe-S phase diagram (Fig. Emf data and thermodynamic information on these reactions are available in detail in the literature.…”