| abstract |
The electrode for an electrochemical device of the present invention includes an electrode mixture layer containing, as an active material, a lithium-containing composite oxide represented by a general composition formula: Li 1 + x MO 2 (1). In the general composition formula (1), , −0.3 ≦ x ≦ 0.3, and M represents an element group containing Ni, Mn, and Mg, and Ni contained in the element group M with respect to the total number of elements in the element group M, When the ratio of the number of elements of Mn and Mg is expressed in mol% units as a, b and c, respectively, 70 ≦ a ≦ 97, 0.5 <b <30, 0.5 <c <30, −10 <b −c <10 and −8 ≦ (bc) / c ≦ 8, the average valence of Ni is 2.5 to 3.2, and the average valence of Mn is 3.5 to 4.2. The average valence of Mg and the Mg is 1.8 to 2.2. |