Mixed metal oxide and sodium secondary battery

摘要

A sodium secondary battery capable of reducing the amount used of a scarce metal element such as lithium and cobalt and moreover, ensuring a larger discharge capacity after repeating charge/discharge as compared with conventional techniques, and a mixed metal oxide usable as the positive electrode active material therefor. The mixed metal oxide comprises Na, Mn and M1 wherein M1 is Fe or Ni, with a Na:Mn:M1 molar ratio being a:(1−b):b wherein a is a value falling within the range of more than 0.5 and less than 1, and b is a value falling within the range of from 0.001 to 0.5. Another mixed metal oxide is a mixed metal oxide represented by the following formula (1): NaaMn1−bM1bO2 (1) wherein M1, a and b each have the same meaning as above. The positive electrode active material for sodium secondary batteries comprises the mixed metal oxide above.

主权项

1. A sodium secondary battery comprising a positive electrode comprising a positive electrode active material, the positive electrode active material comprising a mixed metal oxide comprising Na, Mn and M1 wherein M1 is Fe or Ni, with a Na:Mn:M1 molar ratio being a:(1−b):b wherein a is a value falling within the range of more than 0.5 and less than 1, and b is a value falling within the range of from 0.05 to 0.25, wherein the mixed metal oxide does not include cobalt.