Fibrous carbon, method for manufacturing same, electrode mixture layer for non-aqueous-electrolyte secondary cell, electrode for non-aqueous-electrolyte secondary cell, and non-aqueous-electrolyte secondary cell

Patent metadata

Field	Value
Publication number	US-2018175391-A1
Application number	US-201615736434-A
Country	US
Kind code	A1
Filing date	Jun 16, 2016
Priority date	Jun 18, 2015
Publication date	Jun 21, 2018
Grant date	—

Abstract

The present invention provides: a fibrous carbon characterized in that the average effective fiber length is 1-100 μm, and the crystallite length (La) measured using X-ray diffraction is 100-500 nm; an electrode mixture layer for a non-aqueous-electrolyte secondary cell, said mixture comprising an electrode active material and a carbon-based electroconductive auxiliary agent containing said fibrous carbon; an electrode for a non-aqueous-electrolyte secondary cell, the electrode comprising a collector and said electrode mixture layer for a non-aqueous-electrolyte secondary cell, the electrode mixture layer being laminated on the collector; and a non-aqueous-electrolyte secondary cell having said electrode for a non-aqueous-electrolyte secondary cell.

First claim

1 . A fibrous carbon having an average effective fiber length of 1 to 100 μm, and a crystallite length (La) of 100 to 500 nm as measured by an X-ray diffraction method.

2 . The fibrous carbon according to claim 1 , wherein the fibrous carbon has an average fiber diameter of 100 nm to 1 μm.

3 . The fibrous carbon according to claim 1 , wherein the fibrous carbon has a boron content of 1 ppm by mass or less.

4 . The fibrous carbon according to claim 1 , wherein the fibrous carbon is a pitch-based carbon fiber.

5 . An electrode mixture layer for a nonaqueous electrolyte secondary battery comprising:
an electrode active material; and a carbon-based electroconductive aid containing the fibrous carbon according to claim 1 .

6 . The electrode mixture layer for a nonaqueous electrolyte secondary battery according to claim 5 , wherein the electrode mixture layer for a nonaqueous electrolyte secondary battery has a thickness of 50 to 5000 μm.

7 . The electrode mixture layer for a nonaqueous electrolyte secondary battery according to claim 5 , wherein the electrode mixture layer for a nonaqueous electrolyte secondary battery does not generate an electrochemical reaction in which the ratio of an integrated value of reduction currents to an integrated value of oxidation currents is 0.6 or less in a cyclic voltammogram (CV) measured in a range of 2.5 to 5 V (vs. Li/Li+) using an ethylene carbonate/ethyl methyl carbonate mixed solution (volume (25° C.) ratio=3/7) containing LiPF 6 in a concentration of 1 mol/L while an electrode including the electrode mixture layer for a nonaqueous electrolyte secondary battery is used as a working electrode, and a lithium metal is used as a counter electrode.

8 . The electrode mixture layer for a nonaqueous electrolyte secondary battery according to claim 5 , wherein the fibrous carbon is a fibrous carbon that satisfies the following formula (1):
IA/IB< 0.02  Formula (1)
(where IA is the highest of current values when the oxidation current takes the maximum value in cyclic voltammogram measurement in a potential range of 2.5 to 4.4 V (vs. Li/Li+), and IB is a current value at 5 V in cyclic voltammogram measurement in a potential range of 2.5 to 5 V (vs. Li/Li+)) in a cyclic voltammogram (CV) measured in a potential range of 2.5 to 4.4 V (vs. Li/Li+) using an ethylene carbonate/ethyl methyl carbonate mixed solution (volume (25° C.) ratio=3/7) containing LiPF 6 in a concentration of 1 mol/L while an electrode including 100 parts by mass of an electrode mixture layer for a nonaqueous electrolyte secondary battery which includes 50 parts by mass of the fibrous carbon and 50 parts by mass of polyvinylidene fluoride is used as a working electrode, and a lithium metal is used as a counter electrode.

9 . An electrode for a nonaqueous electrolyte secondary battery, wherein the electrode for a nonaqueous electrolyte secondary battery includes
a current collector, and the electrode mixture layer for a nonaqueous electrolyte secondary battery according to claim 5 which is laminated on the current collector.

10 . A nonaqueous electrolyte secondary battery comprising the electrode for a nonaqueous electrolyte secondary battery according to claim 9 .

11 . A method for manufacturing a fibrous carbon, the method comprising:
(1) a fiber formation step of preparing a resin composite fiber by molding a resin composition in a molten state to form a mesophase pitch into a fiber, the resin composition including a thermoplastic resin, and 1 to 150 parts by mass of the mesophase pitch based on 100 parts by mass of the thermoplastic resin; (2) a stabilization step of stabilizing the resin composite fiber to prepare a resin composite stabilized fiber; (3) a thermoplastic resin removing step of removing the thermoplastic resin from the resin composite stabilized fiber to prepare a stabilized fiber; and (4) a carbonization and firing step of preparing a fibrous carbon by heating the stabilized fiber under an inert atmosphere to carbonize or graphitize the stabilized fiber, the fiber formation step including mesophase pitch orientation control operation.

12 . The method for manufacturing a fibrous carbon according to claim 11 , wherein
the orientation control operation includes at least one of a method in which strain is applied by shearing and a method in which strain is applied by extension.

13 . The method for manufacturing the fibrous carbon according to claim 11 , wherein
each of the shear strain rate and the extension strain rate in the method in which strain is applied by shearing and the method in which strain is applied by extension is 5 to 10000 s −1 .

14 . The method for manufacturing the fibrous carbon according to claim 11 , wherein
the method in which strain is applied by extension includes extension on the downstream side of the nozzle.

Assignees

• Teijin Ltd

Inventors

• Komura Shinya
• Hirakawa Ryota
• Yachi Kazuki
• Kanematsu Asami
• Daido Takahiro

Classifications

• H01M4/13

  Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof · CPC title

• C01B32/05

  Preparation or purification of carbon not covered by groups C01B32/15, C01B32/20, C01B32/25, C01B32/30 · CPC title

• H01M4/625

  Carbon or graphite · CPC title

• D01F9/14

  by decomposition of organic filaments · CPC title

• D01F9/145 Primary

  from pitch or distillation residues · CPC title