Method for increasing the reversible capacity of lithium transition metal oxide cathodes
AssigneeMoli Energy (1990) Limited
InventorsJeffrey R. Dahn, Eric W. Fuller, Monique N. Richard
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Abstract
A method is disclosed for increasing the reversible capacity of lithium transition metal oxide materials for use as cathodes in non-aqueous lithium batteries. The method involves reduction of oxide materials of the form Li.sub.x M.sub.y O.sub.z, wherein M represents transition metals whereby oxygen is removed while still maintaining the original phase of the material. Use of the method of the invention is particularly useful for oxide materials synthesized at low temperatures and where M is Mn.
Claims46
A method of increasing the reversible capacity of lithium transition metal oxide cathodes of non-aqueous lithium batteries which comprises reducing lithium transition metal oxide materials of the form Li.sub.x M.sub.y O.sub.z, wherein M is one or more transition metals and x, y and z' are numbers greater than zero, with a reducing agent so that oxygen is removed from the material while maintaining the material in its original phase.
A method of producing a material for use as a cathode in a non-aqueous lithium battery comprising:
- treating a lithium transition metal oxide material of the formula Li.sub.x M.sub.y O.sub.z, wherein M is one or more transition metals and x, y and z' are numbers greater than zero, with a reducing agent to remove oxygen from the material without causing a phase change in the material.
A method for preparing a cathode material in a phase with a final surface area and a formula Li.sub.x M.sub.y O.sub.z wherein M is one or more transition metals and x, y and z are numbers greater than zero comprising:
- a) selecting a starting material in said phase with a starting surface area and a formula Li.sub.x M.sub.7 O.sub.z' wherein z' is a number greater than z;
- and
- b) treating said starting material in a reducing environment wherein oxygen is removed and wherein the reversible capacity of said cathode material is greater than that of said starting material.
A method for preparing a cathode material in a phase with a final surface area and a formula Li.sub.x Mn.sub.y O.sub.z wherein x, y and z are numbers greater than zero comprising:
- a) synthesizing, at temperatures below about 500.degree. C., a starting material in said phase with a starting surface area and a formula Li.sub.x Mn.sub.y O.sub.z' wherein z' is a number greater than z;
- and
- b) heating said starting material in a reducing gas mixture wherein oxygen is removed and wherein the reversible capacity of said cathode material is greater than that of said starting material.
A method for increasing the reversible capacity of a first cathode material in a phase with a first surface area and formula Li.sub.x M.sub.y O.sub.z', wherein M is one or more transition metals and x, y and z' are numbers greater than zero, comprising treating the cathode material in a reducing environment to form a second cathode material in said phase with a second surface area and a formula Li.sub.x M.sub.y O.sub.z wherein 0<z<z'.
Dependencies are inferred from the claim text.