Page 186 - Lindens Handbook of Batteries

BATTERY ELECTROLYTES 7.11

7.6 CeRAmIC/GlAssy eleCTROlyTes

Electrolytes of this type have, until recently, been employed primarily in thin-film batteries (about
10 μm stack thickness) (see Chap. 27). Glassy phosphorus oxysulfides were employed for lower-
voltage couples such as Li/TiS , which gave many thousands of cycles even though no liquid electro-
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lyte was present. The short path lengths and good diffusion characteristics of the cathode material
allowed cycling with very little loss in this thin-film configuration. The electrolyte phase was made
by RF magnetron sputtering and had conductivities in the range of 10 S/cm. In later developments,
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a similar thin-film battery was made by utilizing an amorphous material called LIPON, which is a
nonstoichiometric material of lithium, phosphorus, nitrogen, and oxygen. This electrolyte has higher
voltage stability than the oxysulfide glasses, so it could accommodate higher voltage positive materi-
als such as lithiated cobalt oxide or manganese oxide. The LIPON was also made by magnetron sput-
tering, in this case of lithium phosphate in a nitrogen atmosphere, but has much poorer conductivity
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in the range of 10 S/cm, although still high enough for the thin layers employed. Other methods
have subsequently been developed for making the LIPON, such as pulsed laser deposition. Most
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methods for making the electrolytes and the electrodes have been relatively slow and use expensive
machinery in the process. It is clearly the goal of the several companies trying to implement prod-
uct development to find ways to lower the cost of the processes. To this end, recent work at Poly
Plus has utilized a well-known ceramic lithium-ion conductor known as LISICON in combination
with lithium anodes. LISICON has high conductivity (of the order of 1mS/cm), but is known to be
unstable in direct contact with lithium metal. To prevent degradation of the anode, another material is
interposed (in one case, a very thin crystalline electronic insulator such as Li N, which also conducts
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31
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lithium ions and in another, a thin separator containing solution ). Provision is made to completely
encapsulate the lithium metal. Many positive electrodes are under investigation with this electrolyte,
including aqueous air electrodes since the encapsulated lithium package is impervious to and stable
in the presence of water. Another group from Mie University has published several studies utilizing
a similar approach. Because of the good conductivity of the LISICON, much thicker electrodes can
32
be used, and practical high-capacity, high-energy density cells are a distinct possibility. Many details
remain to be worked out, including cell designs, optimal cathode materials, as well as costs.
ReFeReNCes

1. E. A. Schumacher, The Primary Battery, Vol. 1, G. W. Heise and N. C. Cahoon Eds., John Wiley, New York,
1971, p. 179.
2. S. A. Megahed, J. Passaniti, and J. C. Springstead, Handbook of Batteries, 3rd Ed., D. Linden and T. B.
Reddy, Eds., McGraw-Hill, New York, 2002, p. 12.9.
3. Schumacher, The Primary Battery, 1, p. 180.
4. K. J. Cain, C. A. Mendres, and V. A. Maroni, J. Electrochem. Soc. 134, 519 (1987) and references therein.
5. C. Debiemme-Chouvy, J. Vedel, M. Bellissent-Funel, and R. Cortes, J. Electrochem. Soc. 142, 1359 (1995)
and references therein.
6. R. Y. Wang, D. W. Kirk, and G. X. Zhang, J. Electrochem. Soc. 153, C357 (2006).
7. F. Beck and P. Ruetschi, Electrochim. Acta 145, 2467 (2000).
8. B. K. Thomas and D. J. Fray, J. Applied Electrochem. 12, 1 (1982).
9. D. Aurbach and A. Zaban, Chap. 3 in Nonaqueous Electrochemistry, D. Aurbach, Ed., Marcel Dekker, Inc.,
New York, 1999, pp. 81–136.
10. D. Aurbach and Y. Gofer, Chap. 4, ibid., pp. 137–212.
11. G. E. Blomgren, Chap. 2 in Lithium Batteries, J. P. Gabano, Ed., Academic Press, New York, 1983,
pp. 13–42.
12. P. B. Balbuena and Y. Wang, Eds., Lithium Batteries: Solid Electrolyte Interphase, Imperial College Press,
London, 2004.