JP-2026074575-A - Negative electrode for non-aqueous electrolyte energy storage element and non-aqueous electrolyte energy storage element

JP2026074575AJP 2026074575 AJP2026074575 AJP 2026074575AJP-2026074575-A

Abstract

[Problem] To provide a negative electrode for a non-aqueous electrolyte energy storage element using a silicon-based active material, wherein expansion of the negative electrode active material layer during charging and discharging is less likely to occur, and the increase in resistance after the charge-discharge cycle is suppressed, and a non-aqueous electrolyte energy storage element using such a negative electrode for a non-aqueous electrolyte energy storage element. [Solution] A negative electrode for a non-aqueous electrolyte energy storage element according to one aspect of the present invention comprises a negative electrode active material layer containing a silicon-based active material and graphite, wherein the total content of the silicon-based active material and the graphite in the negative electrode active material layer is 95% by mass or more, and the content of the silicon-based active material is 5% by mass or more, the graphite includes artificial graphite, and the ratio of the average particle diameter of the artificial graphite ( DB ) to the average particle diameter of the silicon-based active material ( DA ) ( DB / DA ) is 2.5 or more and 3.5 or less. [Selection Diagram] Figure 1

Inventors

中嶋幸穂

Assignees

株式会社ＧＳユアサ

Dates

Publication Date: 20260507
Application Date: 20241021

Claims (5)

The negative electrode active material layer contains a silicon-based active material and graphite, The total content of the silicon-based active material and the graphite in the above-mentioned negative electrode active material layer is 95% by mass or more, and the content of the silicon-based active material is 5% by mass or more. The above graphite includes artificial graphite. A negative electrode for a non-aqueous electrolyte energy storage element , wherein the ratio (DB/DA) of the average particle size of the synthetic graphite to the average particle size of the silicon-based active material (DA ) is 2.5 or more and 3.5 or less.
The negative electrode for a non-aqueous electrolyte energy storage element according to claim 1, wherein the content of the silicon-based active material in the negative electrode active material layer is 5% by mass or more and 20% by mass or less, and the content of the artificial graphite is 70% by mass or more and 90% by mass or less.
The negative electrode for a non-aqueous electrolyte energy storage element according to claim 1 or claim 2, wherein the above-mentioned graphite further comprises flaky graphite.
The negative electrode for a non-aqueous electrolyte energy storage element according to claim 1 or claim 2, wherein the negative electrode active material layer substantially does not contain non-graphitic carbon, or the negative electrode active material layer further contains non-graphitic carbon, and the non-graphitic carbon content in the negative electrode active material layer is 5% by mass or less.
A non-aqueous electrolyte energy storage element comprising a negative electrode for a non-aqueous electrolyte energy storage element according to claim 1 or claim 2.

Description

This invention relates to a negative electrode for a non-aqueous electrolyte energy storage element and a non-aqueous electrolyte energy storage element. Non-aqueous electrolyte secondary batteries, such as lithium-ion batteries, are widely used in electronic devices like personal computers and communication terminals, as well as automobiles, due to their high energy density. Generally, non-aqueous electrolyte secondary batteries consist of a pair of electrodes electrically isolated by a separator, and a non-aqueous electrolyte interposed between these electrodes. They are configured to charge and discharge by transferring charge-transporting ions between the two electrodes. Besides non-aqueous electrolyte secondary batteries, capacitors such as lithium-ion capacitors and electric double-layer capacitors are also widely used as non-aqueous electrolyte energy storage elements. Non-aqueous electrolyte energy storage devices are known that use silicon materials containing silicon elements, such as metallic silicon and silicon oxide (silicon-based active materials), as the negative electrode active material (see Patent Document 1). Silicon-based materials have advantages such as a larger discharge capacity per unit mass compared to carbon materials such as graphite (carbon-based active materials). Japanese Patent Publication No. 2015-053152 Figure 1 is a perspective view showing a non-aqueous electrolyte energy storage element according to one embodiment of the present invention.Figure 2 is a schematic diagram showing an energy storage device comprising a non-aqueous electrolyte energy storage element according to multiple embodiments of the present invention. First, an overview of the negative electrode and non-aqueous electrolyte energy storage device disclosed herein will be provided. [1] A negative electrode for a non-aqueous electrolyte energy storage element according to one aspect of the present invention comprises a negative electrode active material layer containing a silicon-based active material and graphite, wherein the total content of the silicon-based active material and the graphite in the negative electrode active material layer is 95% by mass or more, and the content of the silicon-based active material is 5% by mass or more, the graphite includes artificial graphite, and the ratio of the average particle diameter of the artificial graphite (D B ) to the average particle diameter of the silicon-based active material (D A ) (D B / D A ) is 2.5 or more and 3.5 or less. The negative electrode for the non-aqueous electrolyte energy storage element described in [1] above (hereinafter also simply referred to as "negative electrode") is a negative electrode using a silicon-based active material, which is less prone to expansion of the negative electrode active material layer during charging and discharging, and suppresses the increase in resistance after the charge-discharge cycle. The reason for this is not clear, but the following reason is speculated. Artificial graphite has a small internal porosity and is relatively hard. Therefore, when artificial graphite is contained together with the silicon-based active material in the negative electrode active material layer, the relatively hard artificial graphite is arranged around the silicon-based active material, which suppresses the expansion of the silicon-based active material during charging, and as a result, the expansion of the negative electrode active material layer during charging and discharging is suppressed. Furthermore, the total content of the silicon-based active material and the graphite in the negative electrode active material layer is 95% by mass or more, and the content of the silicon-based active material is 5% by mass or more. The ratio of the average particle diameter of the synthetic graphite (D B ) to the average particle diameter of the silicon-based active material (D A ) (D B / D A ) is 2.5 or more and 3.5 or less. This ensures that graphite, such as synthetic graphite, is densely and sufficiently arranged around the silicon-based active material. In other words, the voids around the silicon-based active material become smaller, and the expansion and contraction of the silicon-based active material during charging and discharging are further suppressed. In such a case, cracking of the silicon-based active material due to expansion and contraction is suppressed, and the increase in resistance after the charge-discharge cycle is suppressed. For these reasons, it is presumed that the negative electrode described in [1] above is less prone to expansion of the negative electrode active material layer during charging and discharging, and the increase in resistance after the charge-discharge cycle is suppressed. (Regarding graphite and artificial graphite) "Graphite" refers to a carbon material in which the average lattice plane spacing (d 002 ) of the (002) plane, as determined by X-ray diffraction before charging/discharging or