Lithium ion secondary battery production method

Patent metadata

Field	Value
Publication number	US-2018034097-A1
Application number	US-201515550074-A
Country	US
Kind code	A1
Filing date	Feb 16, 2015
Priority date	Feb 16, 2015
Publication date	Feb 1, 2018
Grant date	—

Abstract

A production method is provided for producing a lithium ion secondary battery. The lithium ion secondary battery has an external casing that houses an electrolytic solution and a power generating element. The power generating element includes a positive electrode and a negative electrode layered with a separator. The production method includes first charging the lithium ion secondary battery at a voltage range of 4.0 V or lower and then opening the external casing of the lithium ion secondary battery that has been charged at a range of 4.0 V or lower to discharge gas inside the lithium ion secondary battery to the exterior. Next, the production method further includes re-sealing the external casing and charging the lithium ion secondary battery from which the gas has been discharged until the cell voltage is greater than 4.0 V.

First claim

1 . A production method for producing a lithium ion secondary battery formed by sealing a power generation element having a positive electrode and a negative electrode stacked together with a separator and an electrolytic solution inside an external casing, the production method comprising:
Step (a) charging the lithium ion secondary battery at a cell voltage of the lithium ion secondary battery in a range of 4.0 V or lower, the Step (a) including Step (a1) charging the lithium ion secondary battery at the cell voltage range of 2.8 V or lower and Step (a2) further charging the lithium ion secondary battery that has been charged at the range of 2.8 V or lower in the Step (a1) until the cell voltage is greater than 2.8 V and less than or equal to 4.0 V; Step (b) opening the external casing of the lithium ion secondary battery that has been charged in the Step (a) to discharge gas inside the lithium ion secondary battery to an exterior, and then re-sealing the external casing; and Step (c) charging the lithium ion secondary battery from which the gas has been discharged in the Step (b) until the cell voltage is greater than 4.0 V.

2 . (canceled)

3 . The production method according to claim 1 , wherein
the lithium ion secondary battery is charged by a constant current—constant voltage charging method in the Step (a).

4 . The production method according to claim 1 , further comprising
Step (d) in which the lithium ion secondary battery is left to stand for one hour or more between the Step (a) and the Step (b).

5 . The production method according to claim 1 , wherein
a space between an outer circumferential end of the power generating element and an inner circumferential end of the external casing that opposes the outer circumferential end is sealed in the Step (b).

6 . The production method according to claim 5 , wherein
the lithium ion secondary battery is roll-pressed from the inner circumferential end of the external casing toward the outer circumferential end of the power generating element in the Step (b).

7 . The production method according to claim 5 , wherein
the external casing is configured from a material that can be thermally fused; and the external casing is resealed by a portion of the external casing positioned between the outer circumferential end of the power generating element and an opening portion of the external casing being thermally fused in the Step (b).

8 . The production method according to claim 7 , wherein
the external casing is cut between a thermally fused portion and the opening portion, after the external casing is re-sealed, in the Step (b).

9 . The production method according to claim 1 , wherein
at least the steps after the external casing is sealed to before the external casing is resealed are carried out under reduced pressure in the Step (b).

10 . The production method according to claim 1 , wherein
the lithium ion secondary battery is charged by a constant current—constant voltage charging method, in the Step (c).

11 . The production method according to claim 1 , wherein
the negative electrode of the power generating element contains an aqueous binder.

12 . The production method according to claim 11 , wherein
the aqueous binder is a mixture of styrene butadiene rubber (SBR) and carboxymethyl cellulose (CMC).

13 . (canceled)

14 . (canceled)

15 . (canceled)

Assignees

• Nissan Motor

Inventors

• Uwai Kenta
• Miyatake Kazuki
• Matsuzaki Ikuma
• Sato Masanobu
• Sasaki Yusuke

Classifications

• H01M10/0481

  Compression means other than compression means for stacks of electrodes and separators · CPC title

• H01M2004/028

  Positive electrodes · CPC title

• H01M4/665

  Composites · CPC title

• H01M10/058 Primary

  Construction or manufacture · CPC title

• H01M4/13

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