Electrode material for lithium secondary battery, electrode structure comprising the electrode material and secondary battery comprising the electrode structure

• US 7,378,041 B2
• Filed: 03/26/2004
• Issued: 05/27/2008
• Est. Priority Date: 03/26/2003
• Status: Expired due to Fees

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Kawakami, Soichiro, Asao, Masaya, Ogura, Takao
• Primary Examiner(s): KOPEC, MARK T
• Application Number:
  US10/809,483
• Publication Number:
  US 20040248011A1
• Time in Patent Office: 1,523 Days
• Field of Search: 252/518.1, 252/521.3, 252/520.1, 429/218.1, 429/232
• US Class Current: 252/521.3
• CPC Class Codes: H01M 10/0525 Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
• CPC Class Codes: H01M 4/134 Electrodes based on metals, Si or alloys
• CPC Class Codes: H01M 4/1395 of electrodes based on metals, Si or alloys
• CPC Class Codes: H01M 4/386 Silicon or alloys based on silicon
• CPC Class Codes: H01M 4/405 Alloys based on lithium
• CPC Class Codes: Y02E 60/10 Energy storage using batteries
• CPC Class Codes: Y02P 70/50 Manufacturing or production processes characterised by the final manufactured product

Abstract

There are provided an electrode material for a lithium secondary battery which comprises alloy particles comprising silicon as a major component and having an average particle diameter of 0.02 μm to 5 μm, wherein the size of a crystallite of the alloy is not less than 2 nm but no more than 500 nm and an intermetallic compound containing at least tin is dispersed in a silicon phase and an electrode material for a lithium secondary battery which comprises alloy particles comprising silicon as a major component and having an average particle diameter of 0.02 μm to 5 μm, wherein the size of a crystallite of the alloy is not less than 2 nm but no more than 500 nm and an at least one intermetallic compound containing at least one element selected from the group consisting of aluminum, zinc, indium, antimony, bismuth and lead is dispersed in a silicon phase. Thereby, an electrode material for a lithium secondary battery, an electrode structure comprising the electrode material and a secondary battery comprising the electrode structure are provided in which a drop in capacity due to repeated charging/discharging is small, and the charge/discharge cycle life is improved.

Claims

1. An electrode material for a lithium secondary battery, the electrode material comprising alloy particles, the alloy particles comprising:

a silicon phase as a major component; and

an intermetallic compound dispersed in the silicon phase,

wherein the intermetallic compound contains tin and at least one element selected from the group consisting of copper, nickel, cobalt, iron, manganese, vanadium, molybdenum, niobium, tantalum, titanium, zircon, yttrium, lanthanum, selenium, magnesium and silver,

wherein the alloy particles have an average particle diameter of 0.02 μ

m to 5 μ

m, and

wherein the crystallite size of the silicon phase is not less than 2 nm but no more than 500 nm, as determined by the Scherrer Equation Lc=0.94λ

/(β

cos θ

), where Lc is the crystallite size, λ

is the wavelength of the X-ray beam, β

is the full width at half maximum of peak and θ

is the Bragg angle of diffracted rays.

2. The electrode material for a lithium secondary battery according to claim 1, wherein the intermetallic compound contains at least one element selected from the group consisting of copper, nickel, cobalt, iron, manganese, vanadium, molybdenum, niobium, tantalum, zircon, yttrium, lanthanum, selenium and magnesium.

3. The electrode material for a lithium secondary battery according to claim 1, wherein the alloy particles further comprise at least one metal element present in an elemental metal state selected from the group consisting of tin, aluminum, zinc, indium, antimony, bismuth and lead.

4. The electrode material for a lithium secondary battery according to claim 1, wherein the content of silicon in the alloy particles is not less than 50% by weight but no more than 90% by weight.

5. An electrode structure comprising the electrode material set forth in claim 1, a conductive auxiliary material, a binder and a current collector.

6. The electrode structure according to claim 5, wherein the conductive auxiliary material is a carbonaceous material.

7. A secondary battery, which comprises a negative electrode using the electrode structure set forth in claim 5, an electrolyte and a positive electrode, and which utilizes an oxidation reaction of lithium and a reduction reaction of lithium ions.