Cathode material for lithium-ion secondary battery and lithium-ion secondary battery
A cathode material for a lithium-ion secondary battery which is made of agglomerated secondary particles formed by agglomeration of a plurality of primary particles of electrode active material particles made of a transition metal lithium phosphate compound having an olivine structure that is coated with a carbonaceous material, in which an arithmetic average roughness Ra of agglomerated secondary particle surfaces observed using a three-dimensional scanning electron microscope is 15 nm or more and 25 nm or less.
1. A cathode material for a lithium-ion secondary battery which is made of agglomerated secondary particles formed by agglomeration of a plurality of primary particles of electrode active material particles made of a transition metal lithium phosphate compound having an olivine structure that is coated with a carbonaceous material,
wherein an arithmetic average roughness Ra of agglomerated secondary particle surfaces observed using a three-dimensional scanning electron microscope is 15.7 nm or more and 24.6 nm or less.
2. The cathode material for a lithium-ion secondary battery according to claim 1 ,
wherein a cumulative micropore volume of the cathode material, measured using a mercury porosimeter in a micropore diameter range of 0.01 to 10 μm, is 0.55 to 0.65 cm 3 /g.
3. The cathode material for a lithium-ion secondary battery according to claim 1 ,
wherein a specific surface area of the cathode material is 8 m 2 /g or more and 25 m 2 /g or less, and an oil absorption amount of the cathode material, measured using N-methyl-2-pyrrolidone, is 50 ml/100 g or more.
4. The cathode material for a lithium-ion secondary battery according to claim 1 ,
wherein, in a case in which a cathode mixture layer including the cathode material, a conductive auxiliary agent, and a binding agent in a weight ratio of 90:5:5 (the cathode material:the conductive auxiliary agent:the binding agent) is calendered on a 30 μm-thick aluminum current collector at a total applied pressure of 5 t/250 mm,
an electrode density of the cathode mixture layer after the calendering is 1.4 g/cm 3 or more, and
wherein an oil absorption amount of the cathode material, measured using N-methyl-2-pyrrolidone, is 53 to 65 ml/100 g or more.
5. A lithium-ion secondary battery comprising:
a cathode;
an anode; and
an electrolyte,
wherein the cathode has a cathode mixture layer produced using the cathode material according to claim 1 ,
wherein, in a case in which a cathode mixture layer including the cathode material, a conductive auxiliary agent, and a binding agent in a weight ratio of 90:5:5 (the cathode material:the conductive auxiliary agent:the binding agent) is calendered on a 30 μm-thick aluminum current collector at a total applied pressure of 5 t/250 mm,
and an electrode density of the cathode mixture layer after the calendaring is 1.4 g/cm 3 or more.
6. The lithium-ion secondary battery according to claim 5 ,
wherein the cathode mixture layer includes a cathode material made of agglomerated secondary particles formed by agglomeration of a plurality of primary particles of electrode active material particles represented by General Formula (1) that are coated with a carbonaceous material,
Li x A y D z PO 4 (1)
(here, A represents at least one element selected from the group consisting of Co, Mn, Ni, Fe, Cu, and Cr, D represents at least one element selected from the group consisting of Mg, Ca, Sr, Ba, Ti, Zn, B, Al, Ga, In, Si, Ge, Sc, and Y, 0.9<x<1.1, 0<y≤1, 0≤z<1, and 0.9<y+z<1.1).