Separator for nonaqueous electrolyte secondary battery, nonaqueous electrolyte secondary battery utilizing same, and manufacturing methods of same
View Patent ↗The separator of a nonaqueous electrolyte secondary battery is characterized by having a composite nanofiber fiber which is a nanosize fiber that contains two or more kinds of aqueous resins whose melting points are different.
1. A separator for a nonaqueous electrolyte secondary battery, wherein
the separator has a configuration such that first nanosize fibers and second nanosize fibers cross each other,
the first nanosize fibers only contain a first aqueous resin and has a structure with a three-dimensional crossing,
the second nanosize fibers contain the first aqueous resin and a second aqueous resin that has a melting point lower than a melting point of the first aqueous resin, and
the second aqueous resin is a resin which melts at a shutdown temperature of the separator or more, and the first aqueous resin is a resin which retains fiber structure even at the shutdown temperature or more.
2. The separator for a nonaqueous electrolyte secondary battery according to claim 1 , wherein
the nanosize fiber is configured such that the second aqueous resin is shaped like islands to be distributed within the first aqueous resin.
3. The separator for a nonaqueous electrolyte secondary battery according to claim 1 , wherein
the second nanosize fiber is configured such that all or part of a surface of the first aqueous resin is coated with the second aqueous resin.
4. The separator for a nonaqueous electrolyte secondary battery according to claim 1 , wherein
a volume ratio of the second aqueous resin is 40% or more and 80% or less on such a premise that total volume of the first aqueous resin and the second aqueous resin is 100%.
5. The separator for a nonaqueous electrolyte secondary battery according to claim 4 , wherein
the volume ratio of the second aqueous resin is 50% or more.
6. A nonaqueous electrolyte secondary battery, comprising:
a separator for a nonaqueous electrolyte secondary battery according to claim 1 ;
a positive electrode; and
a negative electrode.
7. A manufacturing method of a separator for a nonaqueous electrolyte secondary battery, wherein
nanosize fibers are formed by utilizing a liquid solution, which contains a first aqueous resin and a second aqueous resin that has a melting point lower than a melting point of the first aqueous resin, by utilizing an electrospinning method, and the separator is produced by crossing the nanosize fibers.
8. A manufacturing method of a nonaqueous electrolyte secondary battery, wherein
a separator for a nonaqueous electrolyte secondary battery which is manufactured with the manufacturing method according to claim 7 , a positive electrode and a negative electrode are combined so that the nonaqueous electrolyte secondary battery is manufactured.