JP-2026075348-A - Negative electrode active material for lithium-ion secondary batteries, method for manufacturing the same, and negative electrode for lithium-ion secondary batteries

JP2026075348AJP 2026075348 AJP2026075348 AJP 2026075348AJP-2026075348-A

Abstract

[Problem] To provide a negative electrode active material for lithium-ion secondary batteries that can suppress the breakdown of silicon particles due to the expansion and contraction of silicon particles associated with the intercalation and release of lithium, thereby suppressing the decrease in discharge capacity retention rate (cycle characteristics) even after repeated charging and discharging. [Solution] A negative electrode active material for a lithium-ion secondary battery, wherein silicon particles are dispersed in a lithium silicate phase, and the lithium silicate phase is a composite mainly composed of a barium-containing glass material. [Selection Diagram] Figure 5

Inventors

高橋和樹
宮脇稔勝
有賀悠太
栗田純志
大澤雅人

Assignees

日本重化学工業株式会社

Dates

Publication Date: 20260508
Application Date: 20241022

Claims (7)

A negative electrode active material for a lithium-ion secondary battery, wherein silicon particles are dispersed in a lithium silicate phase, The lithium silicate phase is a composite mainly composed of a barium-containing glass material, making it a negative electrode active material for lithium-ion secondary batteries.
The negative electrode active material for a lithium-ion secondary battery according to claim 1, characterized in that the composite has a softening point of 500 to 560°C and a crystallization temperature of 600 to 650°C.
The negative electrode active material for a lithium-ion secondary battery according to claim 1, characterized in that the content of silicon particles contained in the negative electrode active material for a lithium-ion secondary battery is 40 to 90% by mass.
The negative electrode active material for a lithium-ion secondary battery according to claim 1, characterized in that the average particle size of the silicon particles is 5 to 100 nm.
The negative electrode active material for a lithium-ion secondary battery according to claim 1, characterized in that the barium-containing glass material contains boron.
A method for producing a negative electrode active material for a lithium-ion secondary battery, wherein silicon particles are dispersed in a matrix mainly composed of a barium-containing glass material having sinterability, Process (I): A process to manufacture a barium-containing glass material by mixing and grinding lithium carbonate, barium carbonate, and silicon dioxide, and then firing them at a temperature of 600 to 1000°C under atmospheric pressure. Step (II): A step of producing a negative electrode active material precursor by mixing and grinding the barium-containing glass material produced in step (I) with silicon particles, Step (III): A step of sintering the negative electrode active material precursor produced in step (II) under an inert gas atmosphere, A method for producing a negative electrode active material for lithium-ion secondary batteries, characterized by containing the following:
A negative electrode for a lithium-ion secondary battery, characterized by containing the negative electrode active material for a lithium-ion secondary battery described in any one of claims 1 to 5.

Description

This invention relates to a negative electrode active material for lithium-ion secondary batteries, a method for producing the same, and a negative electrode for lithium-ion secondary batteries. More specifically, it relates to a negative electrode active material for lithium-ion secondary batteries with excellent cycle characteristics, in which silicon particles are dispersed in a matrix mainly composed of a barium-containing glass material with excellent sinterability, a method for producing the same, and a negative electrode for lithium-ion secondary batteries. Rechargeable batteries are now widely used in devices such as mobile phones, personal computers, power tools, hybrid electric vehicles (HEVs), and electric vehicles (PEVs). In particular, lithium-ion batteries offer high power output and high energy density, making them widely used as batteries for portable devices and vehicles. The negative electrode active material in lithium-ion batteries is primarily graphite. While lithium-ion batteries using graphite as the negative electrode active material exhibit good cycle characteristics, their charging capacity is relatively small, around 372 mAh/g. In recent years, the demand for lithium-ion batteries as automotive batteries has been increasing, leading to a strong desire for even higher energy density. To improve the energy density of lithium-ion batteries, it is necessary to increase the charging capacity through the negative electrode active material. From this perspective, silicon-based negative electrodes, which use silicon material as the negative electrode active material with a charging capacity of 4200 (mA·h/g)—more than 10 times that of graphite material—are attracting attention, and research and development are actively underway. The silicon-based anodes currently in practical use are Si anodes, which are composed solely of pure silicon, and SiO anodes, which are composed of SiO, a mixture of Si and SiO₂ . Here, the SiO anode has a structure in which silicon is dispersed in silicon oxide. Because the silicon oxide suppresses the expansion and contraction of silicon, the SiO anode has superior cycle characteristics compared to the Si anode, which is composed solely of silicon. However, in the SiO anode, during the initial charge, the silicon oxide reacts with lithium as a side reaction to produce Li₄SiO₄ , which reduces the Coulomb efficiency. For this reason, development is also underway on Li-Si-O anodes, in which lithium is pre-doped into the SiO anode. However, Li-Si-O anodes have inferior cycle characteristics compared to graphite anodes, so technical challenges remain. Patent Document 1 discloses an SiO powder that can be used as a negative electrode material for a lithium secondary battery capable of intercalating and deintercalating lithium using a lithium-ion conductive non-aqueous electrolyte, and a method for producing the same. The SiO powder described in Patent Document 1 is a secondary battery SiO powder used as a negative electrode material for lithium secondary batteries, and has a hydrogen content of 80 ppm or higher. Patent Document 2 discloses a powder for the negative electrode of a lithium-ion secondary battery, in which reactivity with water is suppressed. The powder for the negative electrode of a lithium-ion secondary battery described in Patent Document 2 contains lithium-containing silicon oxide powder, and when X-ray diffraction measurements are performed using CuKα rays, the peak height P1 caused by Li₂Si₂O₅ , in which the diffraction angle 2θ appears within a predetermined range, and the peak height P2 caused by Li₂SiO₃ , in which the diffraction angle 2θ appears within a predetermined range, satisfy a certain relationship. Patent Document 3 discloses a negative electrode active material for lithium-ion secondary batteries that can suppress the decrease in discharge capacity retention rate (cycle characteristics) even after repeated charging and discharging. The negative electrode active material for lithium-ion secondary batteries described in Patent Document 3 is a composite in which silicon particles are dispersed in a matrix containing lithium aluminosilicate having a three-dimensional network structure, and the lithium aluminosilicate is represented by a predetermined general formula. Patent Document 4 discloses a negative electrode active material for secondary batteries that can improve the cycle capacity retention rate of secondary batteries. The negative electrode active material described in Patent Document 4 comprises a lithium silicate phase and a silicon phase dispersed within the lithium silicate phase. The lithium silicate phase constituting the negative electrode active material described in Patent Document 4 contains element M and exhibits a spot image in the electron diffraction pattern observed using a transmission electron microscope. Patent No. 4531762Japanese Patent Publication No. 2015-153520Patent No. 7116518International Publication No. 2