Lithium ion secondary battery

Patent metadata

Field	Value
Publication number	US-2018159109-A1
Application number	US-201715819387-A
Country	US
Kind code	A1
Filing date	Nov 21, 2017
Priority date	Dec 7, 2016
Publication date	Jun 7, 2018
Grant date	—

Abstract

A positive electrode includes first positive electrode active material particles and second positive electrode active material particles. The first positive electrode active material particles include 0.1% by mass or more and 1% by mass or less of lithium carbonate and a first lithium transition metal oxide as a remainder. The first lithium transition metal oxide is represented by LiM 1 (1-z1) Mn z1 O 2 (0.05≤z1≤0.20). The second positive electrode active material particles include 0.01% by mass or more and 0.05% by mass or less of lithium carbonate and a second lithium transition metal oxide as a remainder. The second lithium transition metal oxide is represented by LiM 2 (1-z2) Mn z2 O 2 (0.40≤z2≤0.60). An electrolytic solution includes 1% by mass or more and 5% by mass or less of an overcharging additive and a solvent and a lithium salt as a remainder.

First claim

What is claimed is:

1 . A lithium ion secondary battery comprising:
a chassis; a pressure-actuated safety device configured to operate depending on an internal pressure of the chassis; a positive electrode accommodated in the chassis; a negative electrode accommodated in the chassis; and an electrolytic solution accommodated in the chassis, wherein: the positive electrode includes first positive electrode active material particles and second positive electrode active material particles; the first positive electrode active material particles include 0.1% by mass or more and 1% by mass or less of lithium carbonate and a first lithium transition metal oxide as a remainder; the first lithium transition metal oxide is represented by the following first formula
LiM 1 (1-z1) Mn z1 O 2
here, M 1 represents a metal element other than Mn, and z1 satisfies 0.05≤z1≤0.20; the second positive electrode active material particles include 0.01% by mass or more and 0.05% by mass or less of lithium carbonate and a second lithium transition metal oxide as a remainder; the second lithium transition metal oxide is represented by the following second formula
LiM 2 (1-z2) Mn z2 O 2
here, M 2 represents a metal element other than Mn, and z2 satisfies 0.40≤z2≤0.60; the electrolytic solution includes 1% by mass or more and 5% by mass or less of an overcharging additive, and a solvent and a lithium salt as a remainder; and the overcharging additive is a benzene derivative having a lower oxidation potential than the solvent.

2 . The lithium ion secondary battery according to claim 1 , wherein:
the first lithium transition metal oxide is represented by the following third formula
LiNi x1 Co y1 Mn z1 O 2
here, x1, y1, and z1 satisfy 0.40≤x1≤0.45, 0.40≤y1≤0.50, 0.05≤z≤0.20, and x1+y1+z1=1; and the second lithium transition metal oxide is also represented by the following fourth formula
LiNi x2 Co y2 Mn z2 O 2
here, x2, y2, and z2 satisfy 0.20≤x2≤0.40, 0.20≤y2≤0.25, 0.40≤z2≤0.60, and x2+y2+z2=1.

3 . The lithium ion secondary battery according to claim 1 , wherein the benzene derivative is at least one of cyclohexylbenzene and biphenyl.

4 . The lithium ion secondary battery according to claim 1 , wherein the electrolytic solution includes 1% by mass or more and 3% by mass or less of the overcharging additive.

5 . The lithium ion secondary battery according to claim 1 , wherein the first positive electrode active material particles and the second positive electrode active material particles satisfy a relationship of 3:7 to 7:3 (the first positive electrode active material particles:the second positive electrode active material particles) in mass ratio.

Assignees

• Toyota Motor Co Ltd

Inventors

• Tsubouchi Hiroshi
• Isono Motoshi
• Kato Masaki
• Wada Naoyuki
• Takahashi Keiichi
• Okada Yukihiro
• Hashimoto Tatsuya

Classifications

• H01M2/1241

  Electricity · mapped topic

• H01M10/4235

  Safety or regulating additives or arrangements in electrodes, separators or electrolyte (H01M10/4242 takes precedence) · CPC title

• H01M4/505

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

• H01M10/0525 Primary

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

• H01M4/364

  as mixtures · CPC title