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An alkaline, rechargeable electrochemical cell includes a pasted electrode structure in which a composition comprising a paste matrix component includes cobalt in an amount greater than 6 weight percent ranging up to 14 weight percent. The matrix may also include a rare earth such as yttrium. The co

An alkaline, rechargeable electrochemical cell includes a pasted electrode structure in which a composition comprising a paste matrix component includes cobalt in an amount greater than 6 weight percent ranging up to 14 weight percent. The matrix may also include a rare earth such as yttrium. The composition further includes particles of nickel hydroxide dispersed in the matrix, and these particles include cobalt levels ranging from greater than 8 atomic percent up to 15 atomic percent. Cells incorporating these materials have good charging efficiency at elevated temperatures.

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1. A positive electrode composition for use in an alkaline, rechargeable electrochemical cell, said composition comprising: a matrix material comprising a mixture of nickel hydroxide and a cobalt material comprising cobalt metal and/or a cobalt oxide, and/or cobalt hydroxide, wherein the weight perc

1. A positive electrode composition for use in an alkaline, rechargeable electrochemical cell, said composition comprising: a matrix material comprising a mixture of nickel hydroxide and a cobalt material comprising cobalt metal and/or a cobalt oxide, and/or cobalt hydroxide, wherein the weight percent of cobalt in said mixture relative to the nickel component thereof is greater than 6% and less than or equal to 14%; andparticles of nickel hydroxide dispersed in said matrix, said nickel hydroxide particles being doped in their bulk with cobalt, the atomic percent of said cobalt being greater than 8% and less than or equal to 12%, said nickel hydroxide particles also having a coating of cobalt oxyhydroxide disposed thereupon. 2. The electrode composition of claim 1, wherein the weight percent of cobalt in said matrix is in the range of 8% to 12%. 3. The electrode composition of claim 1, wherein said matrix includes a binder. 4. The electrode composition of claim 1, wherein said matrix comprises a paste. 5. The electrode composition of claim 1, wherein said particles of nickel hydroxide are comprised of a plurality of microcrystallites having a particle size of less than 100 angstroms, based on the reflection peak from the plane. 6. The electrode composition of claim 5, wherein said microcrystallites have a particle size of less than 90 angstroms based on the reflection peak from the plane. 7. A positive electrode for use in an alkaline, rechargeable electrochemical cell, said electrode comprising a substrate having the electrode composition of claim 1 supported thereupon. 8. An alkaline, rechargeable electrochemical cell, said cell including the electrode of claim 7. 9. A method of making an electrode for a rechargeable alkaline electrochemical cell, said method comprising the steps of: providing a matrix material comprising a mixture of nickel hydroxide and a cobalt material, said cobalt material comprising cobalt and/or cobalt oxide, wherein the weight percent of cobalt in said mixture, relative to the nickel hydroxide component in said mixture, is greater than 6% percent and less than or equal to 14%;providing particles of nickel hydroxide, said particles including a cobalt dopant wherein the atomic percent of said cobalt dopant is greater than 8% and less than or equal to 12%;disposing said particles in said matrix so as to form an electrode composition;providing a substrate; anddisposing said electrode composition on said substrate. 10. The method of claim 9, wherein said matrix material comprises a paste and further includes a binder. 11. The method of claim 9, wherein said matrix comprises a dry material. 12. The method of claim 9, wherein said substrate is a foamed nickel substrate and wherein said electrode composition is at least partially disposed within the pores of said foam. 13. The method of claim 9, including the further step of contacting said electrode with an electrolyte which comprises an aqueous solution of an alkali metal hydroxide. 14. The method of claim 13, wherein the majority of the alkali metal hydroxide in said electrolyte is sodium hydroxide. 15. The method of claim 9, wherein said particles of nickel hydroxide are comprise of a plurality of microcrystallites having a particle size of less than 100 angstroms based on the reflection peak from the plane. 16. The method of claim 9, wherein the particles of nickel hydroxide are substantially spherical and have an average diameter in the range of 5-20 microns. 17. A positive electrode composition for use in an alkaline, rechargeable electrochemical cell, said composition comprising: a matrix material comprising a mixture of nickel hydroxide, a cobalt material comprising cobalt metal and/or a cobalt oxide, and a rare earth material, wherein the weight percent of cobalt in said mixture relative to the nickel component thereof is greater than 6% and less than or equal to 14%; and a rare earth material; andparticles of nickel hydroxide doped in their bulk with cobalt dispersed in said matrix, the atomic percent of said cobalt being greater than 8% and less than or equal to 12%, said nickel hydroxide particles having a coating of cobalt oxyhydroxide disposed thereupon. 18. The positive electrode composition of claim 17, wherein said rare earth material comprises yttrium and/or yttrium oxide. 19. The positive electrode composition of claim 18, wherein the amount of yttrium in said rare earth material is in the range of 0.5 to 5 weight percent. 20. The positive electrode composition of claim 18, wherein the amount of yttrium in said rare earth material is in the range of 0.5 to 2 weight percent.