Lithium secondary battery
View Patent ↗The present disclosure relates to a lithium secondary battery which ensures reaction uniformity even though it uses a high-loading electrode, and thus has high capacity and improved cycle characteristics. The lithium secondary battery includes: an electrode assembly including a positive electrode, a negative electrode and a separator interposed between the positive electrode and the negative electrode; an electrolyte including a lithium salt and an organic solvent; and a battery casing receiving the electrode assembly and the electrolyte, wherein the positive electrode has a loading amount of 3.5 mAh/cm 2 or more, the separator has an air permeability of 200-1200 sec/100 mL, and the electrolyte has a lithium ion conductivity of 11-20 mS/cm.
1. A lithium secondary battery which comprises: an electrode assembly including a positive electrode, a negative electrode and a separator interposed between the positive electrode and the negative electrode; an electrolyte including a lithium salt, and additive, and an organic solvent; and a battery casing receiving the electrode assembly and the electrolyte,
wherein the positive electrode has a loading amount of 4.5 mAh/cm 2 , the separator has an air permeability of 900sec/100 mL,
wherein the electrolyte has a lithium ion conductivity of 13.5-14.0 mS/cm and a viscosity of 1.0 cP to 3.0 cP at 25° C.,
wherein the organic solvent comprises a cyclic carbonate and an acyclic carbonate,
wherein the cyclic carbonate is present in an amount of 10 vol % to 40 vol % based on the total volume of the organic solvent,
wherein the acyclic carbonate is present in an amount of 60 vol % to 90 vol % based on the total volume of the organic solvent, wherein the additive includes vinylene carbonate, 1,3-propane sultone, and ethylene sulfate, and
wherein the air permeability being determined by measure the time required for 100 mL of air to pass through 1 cm 2 of the separator at room temperature under a pressure of 0.05 MPa.
2. The lithium secondary battery according to claim 1 , wherein the separator has a thickness of 2-50 μm.
3. The lithium secondary battery according to claim 1 , wherein the separator is a porous polymer substrate.
4. The lithium secondary battery according to claim 3 , wherein the porous polymer substrate comprises polyethylene, polypropylene, or a combination thereof.
5. The lithium secondary battery according to claim 1 , wherein the lithium salt is LiPF 6 .
6. The lithium secondary battery according to claim 1 , wherein the cyclic carbonate is ethylene carbonate (EC), and
wherein the acyclic carbonate is selected from the group consisting of dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), and a combination thereof.
7. The lithium secondary battery according to claim 1 , wherein the positive electrode has a thickness of 100μm.
8. The lithium secondary battery according to claim 6 , wherein the organic solvent further comprises ethyl acetate.