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United States Patent 5,846,673
Saidi, et. al. Dec. 8, 1998
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Additive to stabilize electrochemical cell
Abstract
The present invention provides a novel composition and method for preventing decomposition of one or more electrochemical cell components comprising an electrode having an active material, and an electrolyte. The method of the invention, for the first time, effectively overcomes problems which arise between the interaction of cell components and contaminate water retained in a cell. Such contaminate water reacts with the electrolyte which comprises a salt of lithium in a solvent. Solubilizing of the salt in solution with attendant interaction between the salt and water causes formation of hydrogen-containing acids. The method of the invention effectively blocks decomposition of a lithium metal oxide cathode active material, and particularly lithium manganese oxide (LMO, nominally LiMn(2) O(4)). Such decomposition is prevented by including in the cell a basic compound which forms an electron donor species in the electrolyte solution; and by neutralizing at least a portion of the acid by reacting the donor species with the hydrogen-containing acids thereby preventing decomposition of the lithium manganese oxide by the acid. The preservation of the lithium manganese oxide prevents degradation of other cell components by other mechanism. The basic compound is desirably an organic base, preferably a butylamine.
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Inventors: Saidi; M. Yazid (Henderson, NV); Gao; Feng (Henderson, NV); Barker; Jeremy (Henderson, NV); Scordilis-Kelley; Chariclea (Henderson, NV).
Assignee: Valence Technology, Inc. (Henderson, NV).
Appl. No.: 762,079
Filed: Dec. 9, 1996
Intl. Cl. : H01M 10/40
Current U.S. Cl.: 429/195; 429/198; 429/224
Field of Search: 429/195, 198, 224
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References Cited | [Referenced By]
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U.S. Patent Documents
4,279,972 Jul., 1981 Moses 429/50
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4,662,065 May, 1987 Marincic et al. 429/224 X
4,880,714 Nov., 1989 Bowden 429/198 X
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5,296,319 Mar., 1994 Bito et al. 429/194
5,316,876 May, 1994 Kuriyama et al. 429/197
5,399,447 Mar., 1995 Chaloner-Gill et al. 429/191
5,419,985 May, 1995 Koksbang 429/212
5,427,875 Jun., 1995 Yamamoto et al. 429/223
5,435,054 Jul., 1995 Tonder et al. 29/623.5
5,463,179 Oct., 1995 Chaloner-Gill et al. 429/192
5,474,858 Dec., 1995 Merritt 429/57
5,482,795 Jan., 1996 Chaloner-Gill 429/12
Foreign Patent Documents
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0 614 239 A Sept., 1994 EP
WO 96/29750 Sept., 1996 EP
0 785 586 A Jul., 1997 EP
59 081 870 May, 1984 JP
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Other References
G. Herlen, B. Fahys, M. Szekely, E. Sutter, C. Mathieu, M. Herlem, and J.F. Penneau, n-Butylamine as Solvent for Lithium Salt Electrolytes, Structure and Properties of Concentrated Solutions, Electrochimica Acta, vol. 41, No. 17, 2753-2760, 1996 (Month unknown).
Gofer, et al., "Solutions of LiAsF(6) in 1,3--Dioxolane for Secondary Lithium Batteries"; Journal of Power Sources, vol. 39, No. 2, 1 Jul. 1992, 163-178.
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