Positive electrode material for secondary battery, method for manufacturing the same, and lithium-ion secondary battery
A positive electrode material for a secondary battery, wherein the positive electrode material includes a triclinic crystal structure and is represented by Li 4+x (Fe 1−z M z ) 4−0.5x (P 2 O 7 ) 3 , where −0.65≤x≤0.75, 0.0<z≤0.7, and M represents a divalent metal other than Fe.
1. A positive electrode material for a secondary battery,
wherein the positive electrode material includes a triclinic crystal structure and is represented by Li 4+x (Fe 1−z Mg z ) 4−0.5x (P 2 O 7 ) 3 , where −0.65≤x≤0.75, 0.0<z≤0.7.
2. The positive electrode material according to claim 1 ,
wherein the crystal structure belongs to Space group P-1.
3. A lithium-ion secondary battery comprising:
a positive electrode including the positive electrode material for a secondary battery;
a negative electrode; and
an electrolyte,
wherein the positive electrode material includes a triclinic crystal structure and is represented by Li 4+x (Fe 1−z Mg z ) 4−0.5x (P 2 O 7 ), where −0.65≤x≤0.75, 0.0<z≤0.7.
4. The lithium-ion secondary battery according to claim 3 ,
wherein the crystal structure belongs to Space group P-1.
5. A method for manufacturing a positive electrode material for a secondary battery, the method comprising:
generating a mixture by mixing a lithium source, an iron source, a magnesium source, and a phosphate source with one another; and
performing a heat treatment on the mixture to acquire a positive electrode material for secondary batteries which includes a triclinic crystal structure and is represented Li 4+x (Fe 1−z Mg z ) 4−0.5x (P 2 O 7 ) 3 , where −0.65≤x≤0.75, 0.0<z≤0.7.
6. The method according to claim 5 ,
wherein the heat treatment is performed at 470° C. or more and 720° C. or less.
7. The method according to claim 5 ,
wherein the heat treatment is performed in an inert atmosphere.