Nonaqueous electrolyte secondary battery positive electrode active material and method for producing same, and nonaqueous electrolyte secondary battery which uses positive electrode active material

Patent metadata

Field	Value
Publication number	US-12381215-B2
Application number	US-202418612290-A
Country	US
Kind code	B2
Filing date	Mar 21, 2024
Priority date	Oct 31, 2017
Publication date	Aug 5, 2025
Grant date	Aug 5, 2025

Abstract

The present invention provides a composite oxide that can achieve a high low-temperature output characteristic, a method for manufacturing the same, and a positive electrode active material in which the generation of soluble lithium is suppressed and a problem of gelation is not caused during the paste preparation. A positive electrode active material for non-aqueous electrolyte secondary batteries, including a lithium-metal composite oxide powder including a secondary particle configured by aggregating primary particles containing lithium, nickel, manganese, and cobalt, or a lithium-metal composite oxide powder including both the primary particles and the secondary particle, wherein the secondary particle has a hollow structure inside as a main inside structure, the slurry pH is 11.5 or less, the soluble lithium content rate is 0.5[% by mass] or less, the specific surface area is 2.0 to 3.0 [m 2 /g], and the porosity is 20 to 50 [%].

First claim

The invention claimed is:

1. A method for evaluating a characteristic of a positive electrode active material for non-aqueous electrolyte secondary batteries,
the characteristic being a “slurry pH” indicating a pH of a slurry containing water and the positive electrode active material as a solid body component, the method comprising:
by adding the positive electrode active material to the water so that the slurry contains the positive electrode active material at a concentration of 50 g/L;
maintaining a state where the slurry is stirred for 30 minutes; and
obtaining the slurry pH by measuring the pH of the slurry with a “pH meter” in the state where the slurry is stirred.

2. A method for evaluating a characteristic of a positive electrode active material for non-aqueous electrolyte secondary batteries,
the positive electrode active material for non-aqueous electrolyte secondary batteries containing lithium,
the characteristic being a “soluble lithium content rate” indicating a lithium amount contained in the positive electrode active material soluble in water being a liquid component of a slurry containing the positive electrode active material and the water, the method comprising:
adding the positive electrode active material to the water so that the slurry contains the positive electrode active material at a concentration of 20 g/L;
maintaining a state where the slurry is stirred for 10 minutes;
filtering the slurry; and
obtaining the soluble lithium content rate by measuring the lithium contained in an obtained filtrate with an ICP optical emission spectrometer.

3. A method for evaluating a characteristic of a positive electrode active material for non-aqueous electrolyte secondary batteries,
the characteristic being a porosity representing a measure of an amount of an internal space of the positive electrode active material,
the method comprising:
a first process of embedding a lithium-metal composite oxide in a resin;
a second process of exposing a cross section of a particle of the lithium-metal composite oxide embedded in the resin by cutting the particle using a cross-section polisher by argon sputtering;
a third process of observing the exposed cross section of the particle using a scanning electron microscope; and
a fourth process of determining a porosity by analyzing an image of the observed cross section of the particle with image analysis software so that a void of the image is analyzed as a black part and a dense portion is analyzed as a white part and calculating an area ratio of the black part/(the black part+the white part) for the cross section of any 20 or more of the particles.

Assignees

• Sumitomo Metal Mining Co

Inventors

• Oshita Hiroko
• Ryoshi Kazuomi
• Aida Taira
• Yamaji Koji
• Okada Jiro

Classifications

• H01M4/366

  as layered products · CPC title

• H01M4/362

  Composites · CPC title

• H01M2004/028

  Positive electrodes · CPC title

• H01M2004/021

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

• H01M10/0525

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