4. The method of claim 1, wherein, when an average particle diameter (D50) of the transition metal precursor is in a range of 5 μm to 10 μm, the temperature of the first temperature holding section is in the range of 400° C. to 600° C.
the transition metal precursor
average particle diameter (D50
a range of 5 μm to 10 μm
μm
the first temperature holding section
temperature
in the range of 400° C. to 600° C
° C