| abstract |
The present invention provides an electrode material suitable for use as a cathode in a sodium electrochemical cell or battery, the electrode comprising a layered material of formula Na c Li d Ni e Mn f M z O b , wherein M comprises one or more metal cation, 0.24≦c/b≦0.5, 0<d/b≦0.23, 0≦e/b≦0.45, 0≦f/b≦0.45, 0≦z/b≦0.45, the combined average oxidation state of the metal components (i.e., Na c Li d Ni e Mn f M z ) is in the range of about 3.9 to 5.2, and b is equal to (c+d+Ve+Xf+Yz)/2, wherein V is the average oxidation state of the Ni, X is the average oxidation state of the Mn, and Y is the average oxidation state of the M in the material. The combined positive charge of the metallic elements is balanced by the combined negative charge of the oxygen anions, the Na is predominately present in a sodium layer, and the Mn, Ni, and M are predominately present in a transition metal layer. |