Electrode for secondary battery, secondary battery, and manufacturing method of the electrode and the secondary battery

Patent metadata

Field	Value
Publication number	US-2016359189-A1
Application number	US-201515121428-A
Country	US
Kind code	A1
Filing date	Jan 16, 2015
Priority date	Feb 28, 2014
Publication date	Dec 8, 2016
Grant date	—

Abstract

Electrode 6 for a secondary battery to be laminated with another type of electrode 1 , with separator 20 interposed therebetween, to constitute a battery electrode assembly, is comprised of collector 8 and active material layer 7 formed on collector 8 , and electrode 6 includes a coated part in which active material layer 7 is formed on collector 8 and an uncoated part in which active material layer 7 is not formed on collector 8 . Active material layer 7 includes, in at least a part of the outer peripheral portion of the coated part, high density part 7 a having a smaller thickness and a higher density than those of a portion other than the outer peripheral portion.

First claim

1 . An electrode for a secondary battery to be laminated with another type of electrode, with a separator interposed therebetween, to constitute a battery electrode assembly, which is comprised of a collector and an active material layer formed on the collector; comprising
a coated part in which the active material layer is formed on the collector; and an uncoated part in which the active material layer is not formed on the collector, wherein the active material layer includes, in at least a part of an outer peripheral portion of the coated part, a high density part having a smaller thickness and a higher density than those of a portion other than the outer peripheral portion.

2 . The electrode for the secondary battery according to claim 1 , the electrode being a negative electrode alternately laminated with a positive electrode that is the other type of electrode, with the separator interposed therebetween.

3 . The electrode for the secondary battery according to claim 1 , wherein the high density part is positioned at an outer edge part of the coated part.

4 . The electrode for the secondary battery according to claim 1 , wherein:
the active material layer further includes a non-high density part positioned at the outer edge part of the coated part, smaller in thickness than a portion other than the outer peripheral portion, and lower in density than the high density part; and the high density part is positioned closer to the center than the non-high density part in the outer peripheral portion of the coated part.

5 . The electrode for the secondary battery according to claim 1 , wherein an average density of the high density part is not less than 110% and not more than 125% of an average density of the portion other than the outer peripheral portion.

6 . The electrode for the secondary battery according to claim 1 , wherein:
the part of the negative electrode other than the outer peripheral portion of the active material layer has a thickness which is not less than 50 μm and not more than 70 μm and an average density which is not less than 1400 kg/m 3 and not more than 1500 kg/m 3 or less; and the high density part is smaller in thickness than the part other than the outer peripheral portion, and has a thickness which is not less than 41.5 μm and not more than 67.5 μm and an average density which is not less than 1550 kg/m 3 and not more than 1750 kg/m 3 .

7 . The electrode for the secondary battery according to claim 6 , wherein the active material layer is made of a material including carbon.

8 . A secondary battery comprising:
a battery electrode assembly including the electrode for the secondary battery according to claim 1 , which is used as a negative electrode, the separator, and a positive electrode alternately laminated with the negative electrode with the separator interposed therebetween; an exterior container for housing the battery electrode assembly; and an electrolyte housed together with the battery electrode assembly in the exterior container.

9 . The secondary battery according to claim 8 , wherein:
the positive electrode is comprised of a collector and an active material layer applied on the collector, and the positive electrode includes a coated part in which the active material layer is formed on the collector, and an uncoated part in which the active material layer is not formed on the collector; an insulating member is disposed to cover a boundary portion between the coated part and the uncoated part; and the high density part of the negative electrode is provided at a position planarly overlapping a part of the insulating member.

10 . The secondary battery according to claim 8 , wherein:
the positive electrode is comprised of a collector and an active material layer applied on the collector, and the positive electrode includes a coated part in which the active material layer is formed on the collector, and an uncoated part in which the active material layer is not formed on the collector; an insulating member is disposed to cover a boundary portion between the coated part and the uncoated part of the negative electrode; and the high density part is provided at a position planarly overlapping a part of the insulating member.

11 . The secondary battery according to claim 8 , the secondary battery being a lithium ion secondary battery.

12 . A method for manufacturing an electrode for a secondary battery to be laminated with another type of electrode, with a separator interposed therebetween, to constitute a battery electrode assembly, comprising:
a step of forming an active material layer in a part of a collector to provide a coated part in which the active material layer is formed, and an uncoated part in which the active material layer is not formed; and a step of locally pressing and compressing at least a part of an outer peripheral portion of the coated part to form a high density part small in thickness and high in density.

13 . The method for manufacturing the electrode for the secondary battery according to claim 12 , wherein in the step of forming the high density part, the high density part is formed at an outer edge part of the coated part.

14 . The method for manufacturing the electrode for the secondary battery according to claim 12 , wherein in the step of forming the high density part, a position closer to the center than an outer edge part in the outer peripheral portion of the coated part is locally compressed to form the high density part inside a non-high density part while leaving the non-high density part small in thickness and not high in density at the outer edge part of the coated part.

15 . The method for manufacturing the electrode for the secondary battery according to claim 12 , further comprising a step of pressing and compressing the entire coated part after the step of providing the coated part and the uncoated part and before the step of forming the high density part,
wherein in the step of forming the high density part, at least a part of the outer peripheral portion of the coated part is locally re-pressed to be further compressed.

16 . The method for manufacturing the electrode for the secondary battery according to claim 15 , wherein:
in the step of pressing and compressing the entire coated part, a thickness of the active material layer is not less than 50 μm and not more than 70 μm and an average density is not less than 1400 kg/m 3 and not more than 1500 kg/m 3 ; and in the step of forming the high density part, a thickness of at least a part of the outer peripheral portion of the coated part is further smaller and not less than 41.5 μm and not more than 67.5 μm, and an average density is not less than 1550 kg/m 3 and not more than 1750 kg/m 3 .

17 . The method for manufacturing the electrode for the secondary battery according to claim 16 , wherein the active material layer is formed by applying a material including carbon.

18 . The method for manufacturing the electrode for the secondary battery according to claim 12 , wherein in the step of forming the high density part, an average density of the high density part is not less than 110% and not more than 125% of an average density of a portion other than the outer peripheral portion.

19 . A method for manufacturing a secondary battery, comprising:
each step of the method for manufacturing the electrode for the secondary battery according to claim 12 , which is carried out to form a negative electrode; a step of alternately laminating the negative electrode and a positive

Assignees

• Nec Energy Devices Ltd

Inventors

• Fukatsu Kimiyoshi
• Hayashi Tomohiko

Classifications

• H01M4/623

  fluorinated polymers · CPC title

• H01M2220/30

  Batteries in portable systems, e.g. mobile phone, laptop · CPC title

• H01M2004/021

  Physical characteristics, e.g. porosity, surface area · CPC title

• H01M10/0525 Primary

  Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries · CPC title

• H01M4/0404

  by coating on electrode collectors · CPC title