Non-aqueous electrolyte secondary battery

• US 10,153,481 B2
• Filed: 01/05/2015
• Issued: 12/11/2018
• Est. Priority Date: 01/08/2014
• Status: Active Grant

• Current Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Original Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Inventors: Saka, Hideyuki, Fujita, Hideaki, Takahashi, Keiichi
• Primary Examiner(s): Yanchuk, Stephen J
• Application Number:
  US14/589,414
• Publication Number:
  US 20150194664A1
• Time in Patent Office: 1,436 Days
• CPC Class Codes: H01M 10/052 Li-accumulators
• CPC Class Codes: H01M 10/0587 of accumulators having only wound construction elements, i.e. wound positive electrodes, wound negative electrodes and wound separators
• CPC Class Codes: H01M 4/131 Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
• CPC Class Codes: H01M 4/136 Electrodes based on inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy
• CPC Class Codes: H01M 4/362 Composites
• CPC Class Codes: H01M 4/366 as layered products
• CPC Class Codes: H01M 4/505 of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy
• CPC Class Codes: H01M 4/525 of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
• CPC Class Codes: H01M 4/5825 Oxygenated metallic salts or polyanionic structures, e.g. borates, phosphates, silicates, olivines
• CPC Class Codes: H01M 4/625 Carbon or graphite
• CPC Class Codes: Y02E 60/10 Energy storage using batteries
• CPC Class Codes: Y02P 70/50 Manufacturing or production processes characterised by the final manufactured product

Abstract

Provided is a non-aqueous electrolyte secondary battery which exhibits excellent energy density and excellent input/output density (and especially output density in low SOC regions). This invention discloses a non-aqueous electrolyte secondary battery that includes a positive electrode, a negative electrode and a non-aqueous electrolyte. The positive electrode includes a positive electrode current collector and a positive electrode active material layers formed on the positive electrode current collector. The positive electrode active material layer has two regions that are demarcated in a surface direction of the positive electrode current collector, which are a first region 14a containing mainly a positive active material of lithium iron phosphate, and a second region 14b containing mainly a positive active material of a lithium-transition metal composite oxide.

Claims

1. A non-aqueous electrolyte secondary battery including a positive electrode, a negative electrode and a liquid non-aqueous electrolyte, wherein

the positive electrode includes a positive electrode current collector and a positive electrode active material layer formed on the positive electrode current collector,

the positive electrode active material layer has two regions that are demarcated in the surface direction of the positive electrode current collector, which are a first region containing mainly a positive active material of lithium iron phosphate having an olivine crystal structure and a second region containing mainly a positive active material of a lithium-transition metal composite oxide having a layered and/or a spinel crystal structure, and

an areal proportion of the first region is 3 to 20% when a total area of the positive electrode active material layer is 100%;

the areal portion of the first region is formed continuously.

2. The non-aqueous electrolyte secondary battery according to claim 1, wherein the proportion of the positive active material of lithium iron phosphate is 90 mass % or higher when a total solid content contained in the first region is 100 mass %.

3. The non-aqueous electrolyte secondary battery according to claim 1, wherein

the positive active material of lithium iron phosphate is particulate, and

electrically conductive carbon is attached to the surface of particles of the positive active material of lithium iron phosphate.

4. The non-aqueous electrolyte secondary battery according to claim 1, wherein

the positive electrode current collector has a length extending from one end to the other end and a width,

the positive electrode active material layer is formed along the length of the positive electrode current collector, and

the first region is provided at the one end of the positive electrode current collector in the length direction.

5. The non-aqueous electrolyte secondary battery according to claim 1, wherein

the positive electrode current collector has a length extending from one end to the other end and a width,

the positive electrode active material layer is formed along the length of the positive electrode current collector, and

the first region is provided in only the central part of the positive electrode active material layer in the length direction.

6. The non-aqueous electrolyte secondary battery according to claim 5, wherein

the second region is provided on both end parts of the positive electrode active material layer which is other than the central part in the length direction.

7. The non-aqueous electrolyte secondary battery according to claim 1, wherein

the positive electrode current collector has a length extending from one end to the other end and a width,

the positive electrode active material layer is formed to a band along the length of the positive electrode current collector, and

the first region is formed along the edge of the positive electrode current collector in a width direction.

8. The non-aqueous electrolyte secondary battery according to claim 7, wherein

the second region is formed in a band and disposed along the first region in a width direction.

9. The non-aqueous electrolyte secondary battery according to claim 1, wherein

the positive electrode current collector has a length extending from one end to the other end and a width,

the positive electrode active material layer is formed on both surfaces of the positive electrode current collector along the length of the positive electrode current collector, and

a first surface of the positive electrode current collector comprising

the first region formed in a band from one end in the length direction and

the second region formed in a band and disposed in a portion other than the first region.

10. The non-aqueous electrolyte secondary battery according to claim 9, wherein

the first region is not formed in a second surface of the positive electrode current collector.

11. The non-aqueous electrolyte secondary battery according to claim 9, wherein

the first region has a rectangular shape in a cross section view.

12. The non-aqueous electrolyte secondary battery according to claim 9, wherein

the second region has a rectangular shape in a cross section view.