Phase Relationships in Positive Electrodes of High Temperature Li ‐ Al / LiCl ‐ KCl / FeS2 Cells

Abstract

The phases present in FeS2 electrodes operated in normalLiCl‐normalKCl eutectic electrolyte were determined by x‐ray diffraction and by metallographic examination. The phases were FeS2 , KFeS2 , Li3Fe2S4 , Li2.33Fe0.67S2 , Fe1−xS , Li2FeS2 , LiK6Fe24S26normalCl , Li2S , and Fe. The metallographic and crystallographic characteristics of these phases are presented. The sequence of Li‐Fe‐S phases in the FeS2 electrode was in accord with the sequence predicted from the equilibrium Li‐Fe‐S phase diagram. Two of the Li‐Fe‐S phases found at room temperature ( Li2.33Fe0.67S2 and Li2FeS2 ) result from decomposition on cooling of a solid solution phase: Li2+xFe1−xS2 false(0≤x≤0.33false) .

Mathematical Modeling of Lithium(alloy), Iron Disulfide Cells

“…The Li-Fe-S Phase Diagram.- Figure 1 gives the phase diagram for the Li-Fe-S system that is in accordance with Argonne'sl 6 1 data. the positive electrode in equilibrium when the overall composition of the system is within the region.…”

“…The intermediate phases of the FeS 2 electrode are the subject of some controversy. Tomczuk et a/.1 6 1 at Argonne National Laboratory have accomplished some of the most recent work with this electrode. In their work, the authors summarize the c~mtroversy, and we feel that they also resolve a great deal of it.…”

Electrochemical verification of the redox mechanism of FeS2 in a rechargeable lithium battery

“…For energy storage in lithium batteries, FeS 2 has a theoretical specific capacity of 894 Ah/kg based on the complete conversion of FeS 2 into metallic Fe and Li 2 S. The high specific capacity together with other merits, such as nontoxicity and cost effectiveness, make FeS 2 appealing and competitive in developing the next generation of batteries beyond Li-ion. In particular, the Li/FeS 2 primary battery operating at ambient temperature was already commercialized as early as the 1980's [5], and FeS 2 was proven to be highly reversible in rechargeable lithium batteries operated at high temperatures (375-500 C) [6,7]. Other publications have shown that Li/FeS 2 batteries are capable of being cycled up to 500 cycles in a moderate temperature range of 90-130 C by employing a composite polymer electrolyte [8][9][10].…”

CoS2Coatings for Improving Thermal Stability and Electrochemical Performance of FeS2Cathodes for Thermal Batteries

“…12,13 The discharge reaction of FeS 2 as a cathode material in thermal batteries is as given below: FeS 2 + 3 2 Li + + 3 2 e − → 1 2 Li 3 Fe 2 S 4 ("z-phase") [2] However, the high impedance of Li 3 Fe 2 S 4 (the "z-phase"), which is produced in the previous discharge stage, adversely affects its electrochemical properties. 14 In order to reduce the impedances of the electrodes of thermal batteries, new fabrication methods (such as plasma spraying) have been employed to produce FeS 2 cathodes. 15,16 Further, it has been shown in several studies that the electrochemical performance of thermal batteries can be improved slightly by z E-mail: csulzj1208@163.com the addition of conductive carbonaceous materials (including carbon black and carbon nanotubes) to their FeS 2 cathodes.…”