Method and firing apparatus for manufacturing cathode active material for lithium ion secondary battery

A method for manufacturing a cathode active material used for a lithium ion secondary battery and represented by the following formula (1), comprising:

• a mixing step of mixing lithium carbonate and a compound containing a metal element shown in the following formula (1) other than Li;
• and
• a firing step of producing a lithium composite compound represented by the following formula (1) by firing a precursor produced through the mixing step, wherein
• the firing step includes at least one of a first stage of controlling a firing temperature to less than 720° C. and a second stage of controlling a firing temperature to 720° C. or more and less than 770° C.,
• the firing step further includes a third stage of controlling a firing temperature to 770° C. or more,
• the first stage is controlled to have an atmosphere having an oxygen concentration of from 45% to 75% both inclusive,
• the second stage is controlled to have an atmosphere having an oxygen concentration of from 55% to 85% both inclusive,
• the third stage is controlled to have an atmosphere having an oxygen concentration of from 80% to 100% both inclusive, and
• the firing is performed while a gas discharged from the atmosphere of the third stage is introduced into at least one of the atmosphere of the first stage and the atmosphere of the second stage
• Li1+aM1O2+α (1)
• provided that (a) in the formula (1), M1 is a metal element other than Li and contains at least Ni and (b) a and a are numbers satisfying −0.1≤a≤0.2 and −0.2≤α≤0.2 respectively.