SEPARATOR FOR LITHIUM ION SECONDARY BATTERY, METHOD FOR MANUFACTURE THEREOF, AND LITHIUM ION SECONDARY BATTERY

• US 20110171535A1
• Filed: 09/11/2009
• Published: 07/14/2011
• Est. Priority Date: 09/12/2008
• Status: Active Grant

• Current Assignee: Japan Vilene Company Limited (Toray Industries Incorporated)
• Original Assignee: Japan Vilene Company Limited (Toray Industries Incorporated)
• Inventors: Yamazaki, Hiroaki, Nakamura, Tatsuo, Ohinshi, Hiroshi, Tanaka, Masanao, Kondo, Yuka, Cho, Te Hyon, Miyata, Yoshikazu
• Granted Patent: US 8,741,489 B2
• Time in Patent Office: Days
• US Class Current: 429/247
• CPC Class Codes: H01M 10/0562 Solid materials
• CPC Class Codes: H01M 50/431 Inorganic material
• CPC Class Codes: H01M 50/489 Separators, membranes, diaphragms or spacing elements inside the cells, characterised by their physical properties, e.g. swelling degree, hydrophilicity or shut down properties
• CPC Class Codes: H01M 50/491 Porosity
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

Disclosed are a separator for lithium ion secondary batteries, having an inorganic layer formed from inorganic particles, characterized in that the inorganic particles have a particle diameter distribution in which the 50% cumulative particle diameter D₅₀ is in the range of 100 nm to 500 nm, the 10% cumulative particle diameter D₁₀ is 0.5D₅₀ or more, and the 90% cumulative particle diameter D₉₀ is 2D₅₀ or less; a method for manufacturing the separator; and a lithium ion secondary battery using the separator. When the separator is used, there can be produced a lithium ion secondary battery in which a short circuit caused by contraction or melting can be definitely prevented, as well as the current density applied to the electrodes during charging and discharging is uniform so that charging and discharging can be efficiently achieved.

Claims

1. A separator for lithium ion secondary batteries, comprising an inorganic layer formed from inorganic particles, wherein the inorganic particles have a particle diameter distribution in which the 50% cumulative particle diameter D₅₀ is in the range of 100 nm to 500 nm, the 10% cumulative particle diameter D₁₀ is 0.5D₅₀ or more, and the 90% cumulative particle diameter D₉₀ is 2D₅₀ or less.

2. The separator for lithium ion secondary batteries according to claim 1, having the inorganic layer on a porous base material.

3. The separator for lithium ion secondary batteries according to claim 2, wherein inorganic particles are present also in the voids of the porous base material.

5. A lithium ion secondary battery using the separator for lithium ion secondary batteries according to claim 1.

6. A lithium ion secondary battery using the separator for lithium ion secondary batteries according to claim 2.

7. A lithium ion secondary battery using the separator for lithium ion secondary batteries according to claim 3.

4. A method for manufacturing a separator for lithium ion secondary batteries, the method comprising:

applying, on a porous base material, a dispersion liquid containing inorganic particles having a particle diameter distribution in which the 50% cumulative particle diameter D₅₀ is in the range of 100 nm to 500 nm, the 10% cumulative particle diameter D₁₀ is 0.5D₅₀ or more, and the 90% cumulative particle diameter D₉₀ is 2D₅₀ or less;

drying the dispersion liquid; and

thereby forming an inorganic layer formed from inorganic particles on a porous base material,

wherein a dispersion medium having a surface contractile force, which acts on the inorganic layer formed from inorganic particles during drying, of 20 kg/cm² or more is used.