Moderate Temperature Na Cells: IV . and as Rechargeable Cathodes in Molten

Abstract

Recent work from this laboratory has shown (1-3) that the layered transition metal dichalcogenides which intercalate Na are useful as cathodes for a rechargeable moderate temperature Na cell which operates at 130~ and utilizes 1,2-Bis(2-methoxy-ethoxy)ethane/NaI(iM) as the electrolyte.) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 134.117.10.200 Downloaded on 2015-07-07 to IP

Moderate Temperature Sodium Cells: V . Discharge Reactions and Rechargeability of and Positive Electrodes in Molten

“…These include a cell utilizing an acidic NaC1-A1C13 melt with SC13+A1C14 -as the positive electrode (6) and batteries employing a $2C12-A1C13 cathode (5). Our studies of VS~ and MoS3, reported elsewhere (1,3,4), and of NiS and NiS2, presented in this paper, represent first examples of the utility of transition metal sulfide cathodes in molten NaC1-A1C13 electrolyte medium. It would be apparent from the data presented that these results may be of considerable scientific and technological importance.…”

“…Consequently, it is reasonable to assume that the overall electrode process in the cycling of the NiS2 cathode is that in Eq. [3] NiS2 + 4Na + + 4e-+ 2NaA1C]4…”

“…Ni + 2NaA1SC12 + 4NaC1 [3] The various intermediate steps may be represented as shown in Eq. [4]- [7] 3NiS~ + 4Na + + 4e-+ 2NaA1CI~ Ni3S4 + 2NaA1SCI~ + 4NaC1 [4] Ni3S4 + 2Na + + 2e-+ NaA1C]4 3NiS + NaA1SC12 + 2NaC1 [5] 3NiS + 2Na + + 2e-+ NaA1C14 Ni3S2 + NaA1SC12 + 2NaC1 [6] Ni3S~ + 4Na + + 4e-+ 2NaAICI4 3Ni + 2NaAISCI~ + 4NaCl [7] Reactions [6] and [7] are common to the NiS and NiS.2 electrodes.…”

“…Sodium batteries which operate in the moderate temperature range of 125~176 have been pursued in recent times (1)(2)(3)(4)(5)(6) as potential alternatives to the liquid Na/molten S system which operates in the range of 350~176 (7). The anode in both types of battery comprises liquid Na contained in a Na + conducting solid electrolyte, usually Na-B-or Na-~"-A1203.…”

“…In the case of VS2, however, the reaction products formed during cathode cycling in molten NaAIC14 exhibited excellent *Electrochemical Society Active Member. rechargeability, providing an extremely useful high energy density rechargeable Na cell (3,4).…”