LITHIUM-ION SECONDARY BATTERY
A lithium-ion secondary battery of the present invention includes a positive electrode, a negative electrode, a non-aqueous electrolytic solution, and a separator. The positive electrode includes, as a positive electrode active material, a lithium-containing oxide that contains at least one element selected from Co and Mn. The negative electrode includes, as a negative electrode active material, graphite having a d 002 in X-ray diffraction of 0.338 nm or less and a carbonaceous material having a d 002 in X-ray diffraction of 0.340 to 0.380 nm. The negative electrode active material contains the carbonaceous material in an amount of 5 to 15 mass %. The non-aqueous electrolytic solution contains LiBF 4 , a nitrile compound having one or more cyano groups, and LiPF 6 . The non-aqueous electrolytic solution contains the LiBF 4 in an amount of 0.05 to 2.5 mass % and the nitrile compound in an amount of 0.05 to 5.0 mass %.
1 - 5 . (canceled)
6 . A lithium-ion secondary battery comprising:
a positive electrode;
a negative electrode;
a non-aqueous electrolytic solution; and
a separator,
wherein the positive electrode comprises, as a positive electrode active material, a lithium-containing oxide that contains at least one element selected from Co and Mn,
the negative electrode comprises, as a negative electrode active material, a mixture of graphite having a d 002 in X-ray diffraction of 0.338 nm or less and a carbonaceous material having a d 002 in X-ray diffraction of 0.340 to 0.380 nm,
the negative electrode active material contains the carbonaceous material in an amount of 5 to 15 mass %,
the non-aqueous electrolytic solution contains LiBF 4 , a nitrile compound having one or more cyano groups, and LiPF 6 , and
the non-aqueous electrolytic solution contains the LiBF 4 in an amount of 0.05 to 2.5 mass % and the nitrile compound in an amount of 0.05 to 5.0 mass %.
7 . The lithium-ion secondary battery according to claim 6 , wherein the nitrile compound is represented by General Formula (1):
NC—(CH 2 ) n —CN (1)
where n is an integer between 2 to 4.
8 . The lithium-ion secondary battery according to claim 6 , wherein the non-aqueous electrolytic solution further contains a phosphonoacetate compound represented by General Formula (2):
where R 1 , R 2 , and R 3 independently represent an alkyl group, an alkenyl group, or an alkynyl group that has 1 to 12 carbon atoms and is optionally substituted with a halogen, and n represents an integer between 0 to 6.
9 . The lithium-ion secondary battery according to claim 6 , wherein the non-aqueous electrolytic solution further contains 1,3-dioxane.
10 . The lithium-ion secondary battery according to claim 6 , wherein the non-aqueous electrolytic solution further contains vinylene carbonate and 4-fluoro-1,3-dioxolan-2-one.