Method for producing a double hydroxide active material
AssigneeVarta Batterie Aktiengesellschaft
InventorsOskar Glemser, Dieter H. Buss, Jurgen Bauer
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Abstract
A positive electrode for alkaline storage cells is disclosed. The active material for the positive electrode is a double hydroxide of the formula [M.sup.2+.sub.(1-x) Fe.sup.3+.sub.x (OH).sub.2 ].sup.x+ [(x/n)X.sup.n-..sub.y H.sub.2 O].sup.x- wherein x is in the range 0.05.ltoreq.x.ltoreq.0.4, M.sup.2+ is an oxidizable and reducible, and X.sup.n- is at least one anion. The double hydroxide has a pyroaurite-like double layer structure and is electrochemically resistant to iron poisoning. In a preferred embodiment, the double hydroxide comprises [Ni.sub.4 Fe(OH).sub.10 ].sup.+ [NO.sub.3.sup.-.yH.sub.2 O].sup.-. Methods for preparing positive electrodes having the double hydroxide active material are also disclosed.
Claims7
A method for producing a double hydroxide having the formula
- [M.sup.2+.sub.(1-x) Fe.sup.3+.sub.x (OH).sub.2 ].sup.x+ [(x/n)X.sup.n-..sub.y H.sub.2 O].sup.x-
- wherein x is in the range 0.05.ltoreq..times..ltoreq.0.4, M.sup.2+ is an oxidizable and reducible cation, and X.sup.n- is at least one anion, as the active material for a positive electrode of a secondary cell, comprising
- preparing an acidified salt solution containing M.sup.2+ and Fe.sup.3+ ions in a molar ratio between 19:1 and 1.5:1, and
- introducing an alkali solution into said acidified salt solution at a predetermined pH value and at a predetermined temperature to precipitate said double hydroxide.
Dependencies are inferred from the claim text.