Nonaqueous electrolyte secondary battery and method for manufacturing nonaqueous electrolyte secondary battery

1. A nonaqueous electrolyte secondary battery including a positive electrode, a negative electrode and a nonaqueous electrolytic solution, wherein

the nonaqueous electrolytic solution contains a nitrile compound having a chain saturated hydrocarbon group and a nitrile group,

the number of carbon atoms in the nitrile compound is four or more,

the positive electrode contains a positive-electrode active material on the surface of which particles of a rare earth compound are uniformly dispersed deposits;

wherein the rare earth compound consists essentially of a hydroxide or a oxyhydroxide of at least one element selected from the group consisting of erbium, samarium, neodymium, dysprosium, holmium, and thulium, and

wherein the positive-electrode active material is at least one selected from the group consisting of lithium cobalt oxide, Ni—Co—Mn-containing lithium composite oxide, Ni—Mn—Al-containing lithium composite oxide and Ni—Co—Al-containing lithium composite oxide.

2. The nonaqueous electrolyte secondary battery according to claim 1 , wherein the particles of the rare earth compound have an average particle diameter of 100 nm or less.

3. The nonaqueous electrolyte secondary battery according to claim 1 , wherein the nitrile compound has two or more nitrile groups.

4. The nonaqueous electrolyte secondary battery according to claim 3 , wherein the nitrile compound is at least one selected from glutaronitrile, adiponitrile and pimelonitrile.

5. The nonaqueous electrolyte secondary battery according to claim 1 , wherein the nitrile compound has three or more nitrile groups.

6. The nonaqueous electrolyte secondary battery according to claim 5 , wherein the nitrile compound is at least one selected from 1,2,3-propanetricarbonitrile and 1,3,5-pentanetricarbonitrile.

7. The nonaqueous electrolyte secondary battery according to claim 1 , wherein an amount of the rare earth compound deposited on the positive-electrode active material is within the range from 0.005% to 0.3% by mass.

8. The nonaqueous electrolyte secondary battery according to claim 1 , wherein the rare earth compound is selected from the group consisting of erbium, samarium, and neodymium.

9. The nonaqueous electrolyte secondary battery according to claim 1 , wherein the rare earth compound is erbium.

10. A nonaqueous electrolyte secondary battery including a positive electrode, a negative electrode and a nonaqueous electrolytic solution, wherein

the nonaqueous electrolytic solution contains a nitrile compound having a chain saturated hydrocarbon group and a nitrile group,

the number of carbon atoms in the nitrile compound is four or more, and

the positive electrode contains a positive-electrode active material comprising a lithium-containing transition metal composite oxide on the surface of which particles of a rare earth compound are uniformly dispersed deposits,

wherein the rare earth compound comprises a hydroxide or an oxyhydroxide of at least one element selected from the group consisting of erbium, samarium, neodymium, ytterbium, terbium, dysprosium, holmium, thulium and lutetium, and

the lithium-containing transition metal composite oxide is only one type selected from lithium cobalt oxide, Ni—Co—Mn-containing lithium composite oxide, Ni—Mn—Al-containing lithium composite oxide and Ni—Co—Al-containing lithium composite oxide.

11. The nonaqueous electrolyte secondary battery according to claim 10 , wherein the lithium-containing transition metal composite oxide is only one type selected from lithium cobalt oxide, Ni—Co—Mn-containing lithium composite oxide, and Ni—Co—Al-containing lithium composite oxide.

12. The nonaqueous electrolyte secondary battery according to claim 11 , wherein only the particles of the rare earth compound are uniformly dispersed deposits on the lithium-containing transition metal composite oxide.