Cathode active material and non-aqueous electrolyte secondary battery using the same

Abstract

A cathode active material having a large capacity and improved charge/discharge cycle characteristics is disclosed. A battery has a cathode ( 2 ) having a cathode active material, an anode ( 3 ) and a non-aqueous electrolyte, and uses a cathode active material composed of a mixture of a first lithium-transition metal composite oxide containing Ni and Co and comprising a layer structure and a second lithium-transition metal composite oxide containing Ni and Mn and comprising a layer structure.

1 - 8 . (canceled) 
   
   
       9 . A cathode active material used for a lithium ion non-aqueous electrolyte secondary battery comprising:
 a mixture of a first cathode material containing at least Ni and Co and a layer structure; and   a second cathode material containing at least Ni and Mn and comprising a layer structure,   wherein said cathode active material contains a lithium composite oxide having a layer structure, containing at least lithium and nickel as components, and in which a shift width of 50% position of jump height of nickel-K shell absorption edge obtainable by measurement using X-ray absorption fine structure (XAFS) analysis technology is equal to or more than 1.0 eV when 50% of the whole lithium contents was extracted.   
   
   
       10 . The cathode active material according to  claim 9 , characterized in that said lithium composite oxide further contains manganese and/or titanium. 
   
   
       11 . The lithium ion non-aqueous electrolyte secondary battery according to  claim 9 , characterized in that, in a lithium ion non-aqueous electrolyte secondary battery having a cathode and an anode respectively consisting of a cathode active material and an anode active material composed of materials capable of inserting and extracting lithium ion; and a non-aqueous electrolyte having lithium ion conductivity, said cathode active material is composed of a lithium composite oxide having a layer structure, containing at least lithium and nickel as components, and in which a shift width of 50% position of jump height of nickel-K shell absorption edge obtainable by measurement using X-ray absorption fine structure (XAFS) analysis technology is equal to or more than 1.0 eV when 50% of the whole nickel contents is extracted. 
   
   
       12 . The lithium ion non-aqueous electrolyte secondary battery according to  claim 11 , characterized in that said lithium composite oxide contains manganese and/or titanium. 
   
   
       13 . The lithium ion non-aqueous electrolyte secondary battery according to  claim 11 , characterized in that an amount of nickel in said cathode active material is adjusted to a range from 5% to 40% in a molar ratio. 
   
   
       14 . The cathode active material used for the lithium ion non-aqueous electrolyte secondary battery according to  claim 9 , characterized in that said cathode active material is composed of a first lithium-transition metal composite oxide mainly containing lithium and cobalt and having a layer structure, and a second lithium-transition metal composite oxide having a layer structure and whose mean discharge voltage resulting from discharge under a current of 0.2 C down to a range of 4.25 V to 3.00 V is lower than that of said first lithium-transition metal composite oxide by 0.05 V or more. 
   
   
       15 . The cathode active material according to  claim 14 , characterized in that said second lithium-transition metal composite oxide is contained in a range from 4% to 50% in molar ratio. 
   
   
       16 . The lithium ion non-aqueous electrolyte secondary battery according to  claim 14 , characterized in that, in a lithium ion non-aqueous electrolyte secondary battery having a cathode and an anode respectively consisting of a cathode active material and an anode active material composed of materials capable of inserting and extracting lithium ion; and a non-aqueous electrolyte having lithium ion conductivity, said cathode active material is composed of a first lithium-transition metal composite oxide mainly containing lithium and cobalt and having a layer structure and a second lithium-transition metal composite oxide having a layer structure and whose mean discharge voltage resulting from discharge under a current of 0.2 C down to a range of 4.25 V to 3.00 V is lower than that of said first lithium-transition metal composite oxide by 0.05 V or more. 
   
   
       17 . The lithium ion non-aqueous electrolyte secondary battery according to  claim 16 , characterized in that said second lithium-transition metal composite oxide is contained in a range from 4% to 50% in molar ratio.