Secondary battery electrode and method for producing the electrode

Patent metadata

Field	Value
Publication number	US-2022293912-A1
Application number	US-202217688748-A
Country	US
Kind code	A1
Filing date	Mar 7, 2022
Priority date	Mar 11, 2021
Publication date	Sep 15, 2022
Grant date	—

Abstract

The method for producing a secondary battery electrode disclosed here includes steps of: preparing a moisture powder formed by aggregated particles that contain electrode active material particles, a binder resin, and solvent, wherein a solid phase, liquid phase, and gas phase in at least 50 number % or more of the aggregated particles in the moisture powder form a pendular or funicular state; forming a coating film composed of the moisture powder, on an electrode current collector, while the gas phase remains present; carrying out depression/elevation transfer into a surface part of the coating film; forming an electrode active material layer by drying the coating film; and pressing the electrode active material layer. The electrode active material particles are aspherical particles in which a ratio of a short side to a long side in a cross sectional view is less than 0.95.

First claim

What is claimed is:

1 . A method for producing a secondary battery electrode, comprising:
a step of preparing a moisture powder that is formed of aggregated particles that at least contain a plurality of electrode active material particles, a binder resin, and solvent, wherein a solid phase, liquid phase, and gas phase in at least 50 number % or more of the aggregated particles in the moisture powder form a pendular state or a funicular state; a step of forming, using the moisture powder, a coating film composed of the moisture powder, on an electrode current collector, while the gas phase remains present; a step of carrying out depression/elevation transfer into a surface part of the formed coating film; a step of forming an electrode active material layer by drying the coating film into which a depression and an elevation have been transferred; and a step of pressing the formed electrode active material layer, wherein the electrode active material particles are aspherical particles in which a ratio of a short side to a long side in a cross sectional view is less than 0.95.

2 . The method for producing a secondary battery electrode according to claim 1 , wherein
if the bulk specific gravity measured by placing an amount (g) of the moisture powder in a container having a prescribed volume (mL) and then leveling the moisture powder without applying a force is referred to as the loose bulk specific gravity X (g/mL), and the specific gravity calculated from the composition of the moisture powder on the assumption that no gas phase is present is referred to as the true specific gravity Y (g/mL), then the ratio of the loose bulk specific gravity X and the true specific gravity Y (Y/X) is 1.2 or more.

3 . The method for producing a secondary battery electrode according to claim 1 , wherein the electrode active material particles are graphite particles.

4 . The method for producing a secondary battery electrode according to claim 1 , wherein the electrode active material particles are aspherical particles in which the ratio of the short side relative to the long side in a cross sectional view is 0.5 or less.

5 . A secondary battery electrode comprising:
an electrode current collector; and an electrode active material layer provided on the electrode current collector, wherein the electrode active material layer contains aspherical graphite particles in which a ratio of a short side relative to a long side in a cross sectional view is less than 0.95, a low density region having a relatively low electrode density and a high density region having a relatively high electrode density are provided at a surface of the electrode active material layer, where, with the electrode active material layer being divided equally into an upper layer, an intermediate layer and a lower layer in the thickness direction from the surface of the active material layer towards the current collector, and when electrode density values (g/cm 3 ) in the upper layer, the intermediate layer and the lower layer in the low density region are denoted by d 1.1 , d 1.2 and d 1.3 respectively, and electrode density values (g/cm 3 ) in the upper layer, the intermediate layer and the lower layer in the high density region are denoted by d H1 , d H2 and d H3 respectively, relationship (d H3 /d L3 )<(d H1 /d L1 ) is satisfied, the electrode active material layer has a plurality of voids, and in a cross sectional view along the thickness direction of the electrode active material layer, a ratio of the number of voids, for which an angle θ between a long axis of the void and a direction perpendicular to the thickness direction falls outside a range±5°, relative to the total number of voids in the upper layer in the low density region is 0.40 or more.

6 . The secondary battery electrode according to claim 5 , wherein d L1 for the upper layer and d L3 for the lower layer in the low density region in the electrode active material layer satisfy the relationship (d L1 /d L3 )<1.1.

Assignees

• Prime Planet Energy & Solutions Inc

Inventors

• Shionoya Haruka
• ENOKIHARA Katsushi
• Mashimo Naohiro
• Kitayoshi Masanori
• Takeshita Shuhei
• Nagano Aiko

Classifications

• H01M4/0404 Primary

  by coating on electrode collectors · CPC title

• H01M4/13 Primary

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

• H01M10/0525

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

• H01M2300/0068

  inorganic · CPC title

• H01M4/043

  involving compressing or compaction · CPC title