Fast ion conductors
OwnerJohn B. Goodenough, Koichi Mizushimainventors
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Abstract
There is interest in the use of solid-solution electrodes as a way of meeting the problems of conventional batteries; Li.sub.a TiS.sub.2 where O.ltoreq.a.ltoreq.1 is known in this respect and may be made by high temperature preparative routes. Fast ion conductors of the formula A.sub.x M.sub.y O.sub.2 where A is Li, Na or K, M is a transition metal e.g. Co or Ni, .ltoreq.x<1 and y.apprxeq.1 have been made for this purpose according to the invention. They cannot be made by high temperature routes when x is substantially less than 1 owing to stability problems. In the invention, they have been made by electrochemical extraction of A.sup.+ ions from compounds of the formula A.sub.x' M.sub.y O.sub.2 where O<x'.ltoreq.1, carried out at low temperature.
Claims3
A method of making an ion conductor of the formula A.sub.x M.sub.y O.sub.2 and having the layers of the .alpha.-NaCrO.sub.2 structure, in which formula A is Li, Na or K, wherein M is a transition metal, wherein x is less than 1;
- and wherein y is approximately equal to 1 which method comprises extracting A.sup.+ cations from a compound having the formula A.sub.x' M.sub.y O.sub.2 wherein A, M, and y are as defined hereinbefore and wherein x' is less than or equal to 1.
Dependencies are inferred from the claim text.