Lithium secondary battery comprising positive electrode active material for synthesis of lithium cobalt oxide and preparation method thereof

Patent metadata

Field	Value
Publication number	US-2018323430-A1
Application number	US-201715740614-A
Country	US
Kind code	A1
Filing date	Jun 12, 2017
Priority date	Jul 21, 2016
Publication date	Nov 8, 2018
Grant date	—

Abstract

The present invention relates to a lithium secondary battery, more particularly, to a lithium secondary battery in which a low-cost positive electrode active material is applied and a negative electrode active material of lithium metal is formed on the positive electrode side, and to a preparation method thereof. The lithium secondary battery according to the present invention can be produced at a low unit cost of production because it employs a complex combined from relatively inexpensive Co, CoO, Co 3 O 4 and Li 2 O, instead of LiCoO 2 which is a common positive electrode active material, and the lithium secondary battery is also easy to mass produce because of its simple manufacturing process since LiCoO 2 is synthesized through an electrochemical reaction due to operating of the battery without a separate heat treatment process.

First claim

1 . A lithium secondary battery comprising a positive electrode including a positive electrode current collector and a positive electrode material mixture; a negative electrode comprising a negative electrode current collector and a negative electrode material mixture; a separator interposed therebetween; and electrolyte,
wherein the positive electrode material mixture comprises a complex combined from Co, CoO, Co 3 O 4 and Li 2 O as a positive electrode active material, and the negative electrode material mixture comprises lithium metal that is separated from the negative electrode current collector and positioned between the positive electrode material mixture and the separator wherein a thin film of lithium is formed on one side of the positive electrode material mixture.

2 . The lithium secondary battery according to claim 1 , wherein the positive electrode active material contained in the positive electrode material mixture is a complex combined from Co, CoO, Co 3 O 4 , and Li 2 O in a molar ratio of 3.8 to 4.2:4.8 to 5.2:0.8 to 1.2:5.8 to 6.2 of Co:CoO:Co 3 O 4 :Li 2 O.

3 . The lithium secondary battery according to claim 1 , wherein the positive electrode active material contained in the positive electrode material mixture is a complex combined from Co, CoO, Co 3 O 4 , and Li 2 O in a molar ratio of 4:5:1:6 of Co:CoO:Co 3 O 4 :Li 2 O.

4 . The lithium secondary battery according to claim 1 , wherein when the lithium secondary battery is initially charged at a temperature of 50 to 70° C., the positive electrode active material of the complex combined from Co, CoO, Co 3 O 4 , and Li 2 O synthesizes LiCoO 2 .

5 . The lithium secondary battery according to claim 1 , wherein when the lithium secondary battery is initially charged at a current density of 0.01 to 0.5 C, lithium metal formed on the positive electrode material mixture is migrated to the negative electrode current collector in the form of lithium ions to form the negative electrode coated with a thin film of lithium on the negative electrode current collector.

6 . The lithium secondary battery according to claim 1 , wherein a polymer protective layer is formed on one side of the negative electrode current collector facing the separator.

7 . The lithium secondary battery according to claim 6 , wherein the polymer protective layer is formed of a lithium ion conductive polymer.

8 . The lithium secondary battery according to claim 6 , wherein the polymer protective layer is selected from the group consisting of polyethylene oxide (PEO), polyacrylonitrile (PAN), polymethylmethacrylate (PMMA), polyvinylidene fluoride (PVDF), polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP), LiPON, Li 3 N, Li x La 1-x TiO 3 (0<x<1) and Li 2 S—GeS—Ga 2 S 3 .

9 . A preparation method for a lithium secondary battery comprising:
forming a positive electrode material mixture on a positive electrode current collector; forming a thin film of lithium on the positive electrode material mixture; sequentially arranging and then laminating a separator and a negative electrode current collector on the thin film of lithium; and injecting electrolyte, wherein the positive electrode material mixture includes a complex combined from Co, CoO, Co 3 O 4 , and Li 2 O as a positive electrode active material.

10 . The preparation method according to claim 9 , wherein the method further comprises forming a polymer protective layer on one side of the negative electrode current collector facing the separator.

Assignees

• Lg Chemical Ltd

Inventors

• Son Byoungkuk
• Jang Minchul
• Choi Junghun
• Sung Da Young
• Park Se Ho

Classifications

• H01M4/364

  as mixtures · CPC title

• H01M4/38

  of elements or alloys · CPC title

• H01M4/0447

  of complete cells or cells stacks · CPC title

• H01M4/62

  Selection of inactive substances as ingredients for active masses, e.g. binders, fillers · CPC title

• H01M4/483

  for non-aqueous cells (H01M4/485 takes precedence) · CPC title