Composite active material for secondary battery, and secondary battery

Patent metadata

Field	Value
Publication number	US-2025038172-A1
Application number	US-202218700404-A
Country	US
Kind code	A1
Filing date	Aug 25, 2022
Priority date	Oct 25, 2021
Publication date	Jan 30, 2025
Grant date	—

Abstract

Provided is a composite active material for a secondary battery with improved initial coulombic efficiency and capacity retention rate of a negative electrode active material, and a secondary battery containing the composite active material for a secondary battery. The composite active material for a secondary battery has silicon particles with an average particle size of 150 nm or less, a matrix phase in which the silicon particles are dispersed, and a silicate compound of at least one metal selected from Li, K, Na, Ca, Mg, and Al. The composite active material for a second battery has the silicate compound in a near-surface of the silicon particles. The silicate concentration in the near-surface of the silicon particles is higher than the silicate concentration in the matrix phase. The composite active material for a secondary battery further has silicon dioxide in the near-surface of the silicon particles.

First claim

1 . A composite active material for a secondary battery, the composite active material comprising:
silicon particles with an average particle size of 150 nm or less; a matrix phase in which the silicon particles are dispersed; and a silicate compound of at least one metal selected from the group consisting of Li, K, Na, Ca, Mg, and Al, the composite active material having the silicate compound in a near-surface of the silicon particles.

2 . The composite active material for a secondary battery according to claim 1 , wherein a silicate concentration in the near-surface of the silicon particles is higher than a silicate concentration in the matrix phase.

3 . The composite active material for a secondary battery according to claim 1 , further comprising silicon dioxide in the near-surface of the silicon particles.

4 . The composite active material for a secondary battery according to claim 3 , wherein a molar ratio of the silicon dioxide is 0.9 or less with a total amount by mole of the silicate compound and the silicon dioxide as 1.

5 . The composite active material for a secondary battery according to claim 1 , wherein the silicate compound is a magnesium silicate compound.

6 . The composite active material for a secondary battery according to claim 5 , wherein the magnesium silicate compound in the near-surface of the silicon particles is a crystalline film with a thickness of 0.2 nm to 10 nm.

7 . The composite active material for a secondary battery according to claim 1 , wherein the matrix phase contains at least a compound represented by SiOxCyNz, where 1≤x≤2, 1≤y≤20, and 0≤z≤0.5.

8 . The composite active material for a secondary battery according to claim 1 , wherein
the silicon particles are flake-like crystals, and a crystallite size obtained from a peak with 2θ of 28.4° in an X-ray diffraction spectrum is 25 nm or less.

9 . The composite active material for a secondary battery according to claim 1 , wherein the composite active material has an average particle size of 1 μm to 15 μm and a specific surface area of 1 m 2 /g to 30 m 2 /g.

10 . A secondary battery comprising the composite active material for a secondary battery according to claim 1 in a negative electrode.

Assignees

• Dainippon Ink & Chemicals

Inventors

• Zhu Peixin
• Kawase Kenichi
• Takeda Kotaro

Classifications

• H01M4/13

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

• H01M4/5825

  Oxygenated metallic salts or polyanionic structures, e.g. borates, phosphates, silicates, olivines · CPC title

• H01M4/62

  Selection of inactive substances as ingredients for active masses, e.g. binders, fillers · CPC title

• H01M4/364

  as mixtures · CPC title

• H01M4/366

  as layered products · CPC title