Positive electrode active material for alkaline secondary battery and alkaline secondary battery including the positive electrode active material

Abstract

A nickel-hydrogen secondary battery includes an electrode group comprising a separator, a positive electrode, and a negative electrode, and the positive electrode contains a positive electrode active material including a base particle comprising a nickel hydroxide particle containing Mn in solid solution and a conductive layer comprising a Co compound and covering the surface of the base particle, wherein the X-ray absorption edge energy of Mn detected within 6500 to 6600 eV by measurement with an XAFS method is 6548 eV or higher.

What is claimed is: 
     
         1 . A positive electrode active material for an alkaline secondary battery, comprising:
 a base particle comprising a nickel hydroxide particle containing Mn in solid solution and a conductive layer comprising a Co compound and covering a surface of the base particle, wherein:   an X-ray absorption edge energy of the Mn detected within 6500 to 6600 eV by measurement with an XAFS (X-ray Absorption Fine Structure) method is 6548 eV or high.   
     
     
         2 . The positive electrode active material for an alkaline secondary battery according to  claim 1 , wherein:
 a content of the Mn is 0.1% by mass or more and 2.0% by mass or less based on a quantity of the nickel hydroxide.   
     
     
         3 . The positive electrode active material for an alkaline secondary battery according to  claim 1 , wherein:
 the conductive layer contains an alkali metal.   
     
     
         4 . The positive electrode active material for an alkaline secondary battery according to  claim 3 , wherein:
 the alkali metal is Na.   
     
     
         5 . The positive electrode active material for an alkaline secondary battery according to  claim 3 , wherein:
 the alkali metal is Na and Li.   
     
     
         6 . The positive electrode active material for an alkaline secondary battery according to  claim 1 , wherein:
 the measurement with an XAFS method is XAFS measurement with a fluorescence yield method.   
     
     
         7 . An alkaline secondary battery comprising a container and an electrode group contained together with an alkaline electrolytic solution in the container, wherein:
 the electrode group comprises a positive electrode and a negative electrode laminated with a separator sandwiched therebetween, and   the positive electrode contains the positive electrode active material for an alkaline secondary battery according to  claim 1 .