Lithium secondary battery

1. A lithium ion secondary battery comprising a positive electrode comprising a positive electrode active material capable of absorbing and releasing lithium, and an electrolyte solution comprising a non-aqueous electrolyte solvent, wherein

the positive electrode comprises 0.08 to 1.5% by weight of a sulfate group relative to the total weight of the positive electrode active material and the sulfate group, and

the non-aqueous electrolyte solvent comprises a sulfone compound represented by Formula (1):

wherein R 1 and R 2 each independently represent substituted or unsubstituted alkyl group, and a carbon atom of R 1 and a carbon atom of R 2 may be bonded through a single bond or double bond to form a cyclic structure.

2. The lithium ion secondary battery according to claim 1 , wherein the positive electrode active material has a charge/discharge region of 4.5 V or more versus lithium.

3. The lithium ion secondary battery according to claim 1 , wherein the positive electrode active material is a lithium-transition metal composite oxide having a spinel structure.

4. The lithium ion secondary battery according to claim 1 , wherein the sulfone compound is at least one selected from sulfolane, dimethyl sulfone, and ethyl methyl sulfone.

5. The lithium ion secondary battery according to claim 1 ,

wherein the non-aqueous electrolyte solvent further comprises a fluorinated ether represented by Formula (4):

R 5 —O—R 4   (4)

wherein R 4 and R 5 each independently represent alkyl group or fluorinated alkyl group, and at least one of R 4 and R 5 is fluorinated alkyl group.

6. A method for producing secondary battery comprising an electrode element, an electrolyte solution, and an outer package, comprising:

a step of preparing a positive electrode comprising a positive electrode active material capable of absorbing and releasing lithium and comprising 0.08 to 1.5% by weight of a sulfate group relative to the total weight of the positive electrode active material and the sulfate group;

a step of preparing an electrode element by arranging the positive electrode and a negative electrode to face each other; and

a step of encapsulating, into an outer package, the electrode element and the electrolyte solution which comprises a non-aqueous electrolyte solvent comprising a sulfone compound represented by Formula (1):

wherein R 1 and R 2 each independently represent substituted or unsubstituted alkyl group, and a carbon atom of R 1 and a carbon atom of R 2 may be bonded through a single bond or double bond to form a cyclic structure.

7. The method for producing a lithium ion secondary battery according to claim 6 , wherein the step of preparing the positive electrode comprises a step of synthesizing the positive electrode active material by using a reaction material comprising a sulfate group.

8. The method for producing a lithium ion secondary battery according to claim 6 , wherein the step of preparing the positive electrode comprises a step of adding a sulfate to the positive electrode active material.

9. The lithium ion secondary battery according to claim 2 , wherein the positive electrode active material comprises at least one selected from the group consisting of positive electrode active materials represented by the following formulas:

Li a (M x Mn 2−x−y Y y )(O 4−w Z w )  (8)

wherein 0.4≦x≦1.2, 0≦y,x+y<2, 0≦a≦1.2, 0≦w≦1, M is at least one selected from the group consisting of Co, Ni, Fe, Cr, and Cu, Y is at least one selected from the group consisting of Li, B, Na, Mg, Al, Ti, Si, K, and Ca, and Z is at least one of F and Cl;

LiMPO 4   (9)

 wherein M is at least one of Co and Ni;

Li 2 MSiO 4

 wherein M is at least one of Mn, Fe and Co; and

Li(Li x M 1−x−z Mn z )O 2   (10)

wherein 0≦x<0.3 and 0.3≦z≦0.7, and M is at least one selected from Co, Ni, and Fe.

10. The lithium ion secondary battery according to claim 2 , wherein the positive electrode active material comprises a positive electrode active material represented by the following formula (8):

Li a (M x Mn 2−x−y Y y )(O 4−w Z w )  (8)

wherein 0.4≦x≦1.2, 0≦y, x+y<2, 0≦a≦1.2, 0≦w≦1 , M is at least one selected from the group consisting of Co, Ni, Fe, Cr, and Cu, Y is at least one selected from the group consisting of Li, B, Na, Mg, Al, Ti, Si, K, and Ca, and Z is at least one of F and Cl.

11. The lithium ion secondary battery according to claim 2 , wherein the positive electrode active material comprises a positive electrode active material represented by the following formula (8-1):

LiNi x Mn 2−x−y A y O 4   (8-1)

wherein 0.4<x<0.6, 0≦y<0.3, and A is at least one selected from Li, B, Na, Mg, Al, Ti, and Si.