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Title: Development of overcharge tolerance in Li/FeS and Li/FeS/sub 2/ cells

Abstract

An innovative application of a self-discharge mechanism for molten-electrolyte Li-alloy/FeS/sub x/ cells has led to the development of overcharge-tolerant cells. Conventional Li-alloy/FeS/sub x/ battery cells require an electronic charger/equalizer. Two versions of the cell have been demonstrated: LiAl+10 Mol% Li/sub 5/Al/sub 5/Fe/sub 2//LiCl-LiBr-KBr (BN, MgO)/FeS/sub 2/ (operated at 400/degree/C) and LiAl+10 mol% Li/sub 5/Fe/sub 2//LiF-LiCl-LiBr(MgO)/FeS (operated at 475/degree/C). These cells exhibit a unique combination of overcharge capacity and extended trickle-charge tolerance at 2--5 mA/cm/sup 2/. The basis for the self-discharge is diffusion of reduced lithium species across the separator by a lithium-shuttle mechanism that is controlled by the Li-activity of the Li-alloy electrode. A bimodal self-discharge rate (a 20-fold increase toward the end of charge) results from a 150--250 mV step increase in Li-activity. Cells having overcharge tolerance have operated with stable performance for greater than 200 cycles. The overcharge tolerance rates are sufficient for battery cells to exhibit built-in charge/equalization capability. 11 refs., 6 figs.

Authors:
; ; ;
Publication Date:
Research Org.:
Argonne National Lab., IL (USA)
OSTI Identifier:
6896200
Report Number(s):
CONF-881061-10; CONF-881061-10
ON: DE89003952
DOE Contract Number:
W-31109-ENG-38
Resource Type:
Conference
Resource Relation:
Conference: Electrochemical Society fall meeting, Chicago, IL, USA, 9 Oct 1988; Other Information: Portions of this document are illegible in microfiche products
Country of Publication:
United States
Language:
English
Subject:
25 ENERGY STORAGE; BATTERY CHARGING; TOLERANCE; CAPACITY; ELECTRIC BATTERIES; ELECTRIC DISCHARGES; ELECTRODES; IRON SULFIDES; LITHIUM ALLOYS; NUMERICAL DATA; ALLOYS; CHALCOGENIDES; DATA; ELECTROCHEMICAL CELLS; INFORMATION; IRON COMPOUNDS; SULFIDES; SULFUR COMPOUNDS; TRANSITION ELEMENT COMPOUNDS 250900* -- Energy Storage-- Batteries

Citation Formats

Kaun, T.D., Holifield, T.F., Nigohosian, M., and Nelson, P.A.. Development of overcharge tolerance in Li/FeS and Li/FeS/sub 2/ cells. United States: N. p., 1988. Web.
Kaun, T.D., Holifield, T.F., Nigohosian, M., & Nelson, P.A.. Development of overcharge tolerance in Li/FeS and Li/FeS/sub 2/ cells. United States.
Kaun, T.D., Holifield, T.F., Nigohosian, M., and Nelson, P.A.. 1988. "Development of overcharge tolerance in Li/FeS and Li/FeS/sub 2/ cells". United States. doi:.
@article{osti_6896200,
title = {Development of overcharge tolerance in Li/FeS and Li/FeS/sub 2/ cells},
author = {Kaun, T.D. and Holifield, T.F. and Nigohosian, M. and Nelson, P.A.},
abstractNote = {An innovative application of a self-discharge mechanism for molten-electrolyte Li-alloy/FeS/sub x/ cells has led to the development of overcharge-tolerant cells. Conventional Li-alloy/FeS/sub x/ battery cells require an electronic charger/equalizer. Two versions of the cell have been demonstrated: LiAl+10 Mol% Li/sub 5/Al/sub 5/Fe/sub 2//LiCl-LiBr-KBr (BN, MgO)/FeS/sub 2/ (operated at 400/degree/C) and LiAl+10 mol% Li/sub 5/Fe/sub 2//LiF-LiCl-LiBr(MgO)/FeS (operated at 475/degree/C). These cells exhibit a unique combination of overcharge capacity and extended trickle-charge tolerance at 2--5 mA/cm/sup 2/. The basis for the self-discharge is diffusion of reduced lithium species across the separator by a lithium-shuttle mechanism that is controlled by the Li-activity of the Li-alloy electrode. A bimodal self-discharge rate (a 20-fold increase toward the end of charge) results from a 150--250 mV step increase in Li-activity. Cells having overcharge tolerance have operated with stable performance for greater than 200 cycles. The overcharge tolerance rates are sufficient for battery cells to exhibit built-in charge/equalization capability. 11 refs., 6 figs.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = 1988,
month = 1
}

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  • To explore the capability of the controlled self-discharge process for chemical overcharge protection, several LiAlSi/LiF-LiCl-LiBr- MgO/FeS and LiAlSi/LiCl-LiBr-KBr-MgO/FeS cells were built and tested. The electrode material formulas do not indicate real compounds; they merely represent electrode compositions that are normalized to one mole of the negative matrix material (Al and Si), thereby fixing the atom ratios of Al:Si:Fe:S in the cell. Overcharge is a serious problem in batteries. Maintaining the charge voltage of each cell at or below the voltage limit and simultaneously reaching equal capacity in each series-connected cell of a lithium-alloy/metal sulfide battery over many cycles are difficultmore » tasks. For lithium-alloy/monosulfide cells, a possible method of chemical overcharge protection is use of a controlled self-discharge process, as described in this article. 11 refs., 3 figs.« less
  • A cell or battery of cells having improved overcharge tolerance and increased power capability, and methods for the construction of such cells or batteries, via electrolyte modification, are described. 5 figs.
  • A cell or battery of cells having improved overcharge tolerance and increased power capability, and methods for the construction of such cells or batteries, via electrolyte modification.
  • Hydrogen gassing and the potential for cell rupture in aerospace nickel cadmium cells is directly related to loss of overcharge protection built into the cell during manufacturing. It is well known that cells having nylon separators contribute to this loss via a hydrolysis reaction of the nylon in the potassium hydroxide electrolyte environment in the cell. The hydrolysis reaction produces lower chain organics which are oxidized by the positive electrode and oxygen. Oxidation of the organics diminishes the overcharge protection. With introduction of the Super NiCd and the Magnum nickel cadmium cells the nylon hydrolysis reaction is eliminated, but anymore » reducing agent in the cell such as nickel or an organic additive can contribute to loss of overcharge protection. The present effort describes analyses made to evaluate the extent of overcharge protection loss in cells which do not have nylon hydrolysis and quantifies the diminished amount of overcharge protection loss as a result of eliminating nylon from aerospace cells.« less