Energy storage device and method for manufacturing energy storage device

Patent metadata

Field	Value
Publication number	US-2019221833-A1
Application number	US-201716330483-A
Country	US
Kind code	A1
Filing date	Sep 6, 2017
Priority date	Sep 7, 2016
Publication date	Jul 18, 2019
Grant date	—

Abstract

An energy storage device is provided that has improved power performance at low temperature. In the present embodiment, an energy storage device is provided that includes an electrode having an active material layer, the active material layer contains at least active material particles, the particles contained in the active material layer gives a volume-based particle size frequency distribution that has a first peak and a second peak appearing in a particle size larger than a particle size of the first peak, and particles having particle sizes equal to or smaller than a particle size Dx have a volume proportion of 49% or more and 62% or less in a volume of whole particles contained in the active material layer, with the particle size Dx defined as a particle size at a local minimum frequency between the first peak and the second peak in the particle size frequency distribution.

First claim

1 . An energy storage device comprising a positive electrode that includes a positive active material layer,
wherein the positive active material layer contains at least positive active material particles, the positive active material particles contained in the positive active material layer gives a volume-based particle size frequency distribution that has a first peak and a second peak appearing in a particle size larger than a particle size of the first peak, and positive active material particles having particle sizes equal to or smaller than a particle size Dx have a volume proportion of 49% or more and 62% or less in a volume of whole positive active material particles contained in the positive active material layer, with the particle size Dx defined as a particle size at a local minimum frequency between the first peak and the second peak in the volume-based particle size frequency distribution.

2 . The energy storage device according to claim 1 , wherein the positive active material layer contains secondary particles formed by aggregation of primary particles of a positive active material.

3 . The energy storage device according to claim 1 , wherein the secondary particles of the positive active material have a pore formed therein, with the pore being equal to or larger than particle sizes of the primary particles constituting the secondary particles.

4 . The energy storage device according to claim 2 , wherein an average diameter Dp of the primary particles and the particle size D1 of the first peak satisfy a relational expression 0.5≤D1/Dp≤2.

5 . The energy storage device according to claim 1 , wherein a particle size D2 of the second peak is 2 μm or more and 5 μm or less.

6 . A method for manufacturing an energy storage device, the method comprising preparing a positive electrode that includes a positive active material layer containing at least positive active material particles,
wherein the preparing the positive electrode includes pressing the positive active material layer containing secondary particles formed by aggregation of primary particles of a positive active material, the pressing the positive active material layer includes:
crushing a part of the secondary particles to allow the positive active material particles contained in the positive active material layer pressed to give a volume-based particle size frequency distribution that has a first peak and a second peak appearing in a particle size larger than a particle size of the first peak, and
crushing the part of the secondary particles to allow positive active material particles having particle sizes equal to or smaller than a particle size Dx to have a volume proportion of 49% or more and 62% or less in a volume of whole positive active material particles contained in the positive active material layer, with the particle size Dx defined as a particle size at a local minimum frequency between the first peak and the second peak in the volume-based particle size frequency distribution.

Assignees

• Gs Yuasa Int Ltd

Inventors

• Shimokawa Ryosuke
• Kako Tomonori
• Ito Shota
• Kawaguchi Kazuki

Classifications

• H01M4/139 Primary

  Processes of manufacture · CPC title

• H01M4/505

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

• H01M4/621

  Binders · 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