Lithium secondary battery and method for producing same
This invention provides a lithium secondary battery capable of bringing about greater cycle characteristics, being in a 4.2 V or higher class. The lithium secondary battery provided by this invention is a 4.2 V or higher class lithium secondary battery using a lithium transition metal composite oxide as a positive electrode active material. The lithium secondary battery comprises a negative electrode at or around which a silicon-containing cyclic compound and/or a reaction product thereof are present. The silicon-containing cyclic compound comprises at least one silicon atom in its ring and has a vinyl group.
1. A method for producing a 4.2 V or higher class lithium secondary battery, the method comprising:
obtaining a positive electrode and a negative electrode, the positive electrode comprising a lithium transition metal composite oxide as a positive electrode active material;
obtaining a non-aqueous electrolyte comprising a silicon-containing cyclic compound; and
supplying the non-aqueous electrolyte obtained to an electrode body comprising the positive electrode and the negative electrode,
wherein the silicon-containing cyclic compound comprises at least one silicon atom in its ring and has at least one vinyl group, and
the silicon-containing cyclic compound is a vinyl group-containing cyclic siloxane represented by a formula (1):
wherein R 1 and R 2 are either the same or different with each being an organic group having 1 to 12 carbon atoms, at least either R 1 or R 2 includes a vinyl group, and n is an integer between 3 and 10.
2. The method according to claim 1 , wherein, in the silicon-containing cyclic compound, all substituents bonded to the silicon atom(s) constituting the ring are vinyl groups.
3. The method according to claim 1 , wherein the positive electrode active material is a spinel lithium transition metal composite oxide comprising Li and further Ni and Mn as transition metals.
4. The method according to claim 1 , wherein the non-aqueous electrolyte comprises a fluorinated carbonate as a non-aqueous solvent in the non-aqueous electrolyte.
5. A 4.2 V or higher class lithium secondary battery comprising:
a positive electrode comprising a lithium transition metal composite oxide as a positive electrode active material;
a negative electrode; and
a non-aqueous electrolyte including a silicon-containing cyclic compound, wherein the silicone-containing cyclic compound comprises at least one silicon atom in its ring and has at least one vinyl group, and
the silicon-containing cyclic compound is a vinyl group-containing cyclic siloxane represented by a formula (1):
wherein R 1 and R 2 are either the same or different with each being an organic group having 1 to 12 carbon atoms, at least either R 1 or R 2 includes a vinyl group, and n is an integer between 3 and 10.
6. The lithium secondary battery according to claim 5 , wherein, in the silicon-containing cyclic compound, all substituents bonded to the silicon atom(s) constituting the ring are vinyl groups.
7. The lithium secondary battery according to claim 5 , wherein the positive electrode active material is a spinel lithium transition metal composite oxide comprising Li and further Ni and Mn as transition metals.
8. The lithium secondary battery according to claim 5 , wherein the non-aqueous electrolyte comprises a fluorinated carbonate as a non-aqueous solvent.
9. The lithium secondary battery according to claim 5 , wherein the negative electrode comprises a negative electrode active material layer including a negative electrode active material, and the negative electrode active material is carbon particles.
10. The lithium secondary battery according to claim 5 , wherein the negative electrode comprises a negative electrode active material layer including carbon particles as negative electrode active material, and
the content of the carbon particles in the negative electrode active material layer is 90% by mass or greater.
11. A vehicle equipped with the lithium secondary battery according to claim 5 .