Laminated body, separator, and nonaqueous secondary battery

Patent metadata

Field	Value
Publication number	US-10014506-B2
Application number	US-201715418169-A
Country	US
Kind code	B2
Filing date	Jan 27, 2017
Priority date	Aug 29, 2014
Publication date	Jul 3, 2018
Grant date	Jul 3, 2018

Abstract

A nonaqueous secondary battery separator, disposed between a cathode and an anode, includes: a porous base material containing a polyolefin as a main component; and a porous layer containing a polyvinylidene fluoride-based resin on at least one surface of the porous base material. The separator satisfies (C)/(D)≤0.13, where (C) represents the average pore diameter (μm) of the porous base material, and (D) represents the porosity of the porous base material, in the porous layer after being immersed for 24 hours in an electrolyte solution having a temperature of 25° C. in which electrolyte solution LiPF 6 having a concentration of 1.0 mole per liter is dissolved in a mixed solvent containing ethyl methyl carbonate, diethyl carbonate, and ethylene carbonate at a volume ratio of 50:20:30, the resin having absorbed the electrolyte solution having a volume of 0.05 to 5.00 cm 3 per square meter of the porous layer.

First claim

The invention claimed is:

1. A separator for a nonaqueous electrolyte lithium secondary battery which separator is disposed between a cathode and an anode both for the nonaqueous electrolyte lithium secondary battery and which separator is used in an electrolytic solution containing a solvent prepared by mixing cyclic carbonate and chain carbonate at a mass ratio within a range of 20:80 to 40:60,
the cyclic carbonate being ethylene carbonate, propylene carbonate, fluoroethylene carbonate, difluoroethylene carbonate, or a mixture of two or more thereof,
the chain carbonate being dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, a fluorine substituent thereof, or a mixture of two or more thereof,
the separator comprising:
a porous base material containing a polyolefin as a main component; and
a porous layer laminated on at least one surface of the porous base material, the porous layer containing a polyvinylidene fluoride-based resin,
the separator satisfying
( C )/( D )≤0.13,

where
(C) represents an average pore diameter of the porous base material, the average pore diameter (C) having a value in μm indicative of a mean value of respective sizes of pores in the porous base material, and
(D) represents a porosity of the porous base material, the porosity (D) having a value indicative of a proportion ((F)/(E)) of a volume (F) of void in the actual porous base material with reference to a volume (E) of the porous base material assumed to have no void,
the polyvinylidene fluoride-based resin accounting for 70% or more by mass of a resin component of the porous layer,
the polyvinylidene fluoride-based resin containing vinylidene fluoride at a proportion of 95 mol % or more in terms of structure units,
an applied amount of the porous layer on one surface of the porous base material being within a range of 0.5 to 1.5 g/m 2 ,
in the porous layer after being immersed for 24 hours in an electrolyte solution having a temperature of 25° C. in which electrolyte solution LiPF 6 having a concentration of 1.0 mole per liter is dissolved in a mixed solvent containing ethyl methyl carbonate, diethyl carbonate, and ethylene carbonate at a volume ratio of 50:20:30, the resin having absorbed the electrolyte solution having a volume of 0.25 to 1.50 cm 3 per square meter of the porous layer,
the porous layer after being immersed for 24 hours in the electrolyte solution having a porosity of 0.5 to 55.0% and an average pore diameter of 0.8 to 95.0.

2. A laminated body, comprising:
a separator according to claim 1 ; and
an electrode sheet.

3. A method for producing a laminated body according to claim 2 , the method comprising the step of
applying, to the porous base material or the electrode sheet, a solution in which the resin for the porous layer is dissolved.

4. A nonaqueous secondary battery, comprising:
a separator according to claim 1 ; and
an electrode sheet.

Assignees

• Sumitomo Chemical Co

Inventors

• Murakami Chikara
• Ogata Toshihiko
• Arise Ichiro
• Kurakane Kosuke
• Yoshimaru Chikae

Classifications

• H01M4/505 Primary

  of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy · CPC title

• H01M50/417

  Polyolefins · CPC title

• H01M50/426 Primary

  Fluorocarbon polymers · CPC title

• H01M50/491

  Porosity · CPC title

• H01M50/449

  having a layered structure · CPC title