CARBON MATERIAL FOR LITHIUM ION SECONDARY BATTERY

• US 20120070733A1
• Filed: 08/22/2011
• Published: 03/22/2012
• Est. Priority Date: 02/20/2009
• Status: Active Grant

• Current Assignee: Mitsubishi Chemical Corporation (Mitsubishi Chemical Group Corp.)
• Original Assignee: Mitsubishi Chemical Corporation (Mitsubishi Chemical Group Corp.)
• Inventors: Yamada, Shunsuke, Yamaguchi, Keita, Sato, Hideharu, Nose, Taisuke
• Granted Patent: US 8,647,776 B2
• Time in Patent Office: Days
• US Class Current: 429/211
• CPC Class Codes: C01B 32/05 Preparation or purification of carbon not covered by groups C01B32/15, C01B32/20, C01B32/25, C01B32/30
• CPC Class Codes: C01B 32/21 After-treatment
• CPC Class Codes: C01P 2002/82 by IR- or Raman-data
• CPC Class Codes: C01P 2004/51 Particles with a specific particle size distribution
• CPC Class Codes: C01P 2006/11 Powder tap density
• CPC Class Codes: C01P 2006/12 Surface area
• CPC Class Codes: C01P 2006/20 Powder free flowing behaviour
• 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 4/133 Electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
• CPC Class Codes: H01M 4/1393 of electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
• CPC Class Codes: H01M 4/587 for inserting or intercalating light metals
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

To provide a negative electrode material capable of giving a lithium ion secondary battery that is sufficiently small in the charge/discharge irreversible capacity observed at the initial cycle stage, has excellent high-temperature storage characteristics, and reduced in the gas generation at the initial cycle stage as well as during high-temperature storage.

A carbon material for lithium ion secondary battery, wherein the surface functional group amount O/C value represented by the following formula 1 is from 1 to 4% and the sum (Cl/C+S₁₆₅/C) of the surface functional group amount Cl/C value represented by the following formula 2 and the surface functional group amount S₁₆₅/C value represented by the following formula 3 is from 0.05 to 0.5%:

Formula 1:

• • O/C value (%)=O atom concentration determined based on the peak area of the spectrum of O1s in X-ray photoelectron spectroscopy (XPS) analysis/C atom concentration determined based on the peak area of the spectrum of C1s in XPS analysis×100
    Formula 2:
  • Cl/C value (%)=Cl atom concentration determined based on the peak area of the spectrum of Cl2p in XPS analysis/C atom concentration determined based on the peak area of the spectrum of C1s in XPS analysis×100
    Formula 3:
  • S₁₆₅/C value (%)=S₁₆₅ atom concentration based on the peak area of the peak near 165 eV in the spectrum corresponding to S2p in XPS analysis/C atom concentration determined based on the peak area of the spectrum of C1s in XPS analysis×100.

Claims

1. A carbon material for lithium ion secondary battery, wherein the surface functional group amount O/C value represented by the following formula 1 is from 1 to 4% and the sum (Cl/C+S₁₆₅/C) of the surface functional group amount Cl/C value represented by the following formula 2 and the surface functional group amount S₁₆₅/C value represented by the following formula 3 is from 0.05 to 0.5%:

Formula 1;

O/C value (%)=O atom concentration determined based on the peak area of the spectrum of O1s in X-ray photoelectron spectroscopy (XPS) analysis/C atom concentration determined based on the peak area of the spectrum of C1s in XPS analysis×

100

Formula 2;

Cl/C value (%)=Cl atom concentration determined based on the peak area of the spectrum of Cl2p in XPS analysis/C atom concentration determined based on the peak area of the spectrum of C1s in XPS analysis×

100

Formula 3;

S₁₆₅/C value (%)=S₁₆₅ atom concentration based on the peak area of the peak near 165 eV in the spectrum corresponding to S2p in XPS analysis/C atom concentration determined based on the peak area of the spectrum of C1s in XPS analysis×

100

2. The carbon material for lithium ion secondary battery as claimed in claim 1, wherein the BET specific surface area (SA) is from 4 to 11 m²/g, the tap density is from 0.7 to 1.3 g/cm³, the Raman R value is from 0.15 to 0.4, and the fluidity index is from 0.4 to 0.53.

3. The carbon material for lithium ion secondary battery as claimed in claim 1, wherein the abundance ratio (3R/2H) of rhombohedral crystal to hexagonal crystal, obtained from X-ray structural analysis (XRD), is 0.20 or more.

4. The carbon material for lithium ion secondary battery as claimed in claim 1, which is produced by a production method comprising:

contacting raw material graphite with an acid containing at least one of hydrochloric acid and sulfuric acid; and

heat-treating said graphite contacted with said acid at 100 to 600°

C.

5. The carbon material for lithium ion secondary battery as claimed in claim 4, wherein the raw material graphite described in claim 4 is natural graphite subjected to a spheroidization treatment, and the surface functional group amount O/C value represented by the formula 1 above of said spheroidized natural graphite is from 1 to 4%.

6. A negative electrode for lithium ion secondary battery, comprising a current collector and an active material layer formed on said current collector, wherein said active material layer contains the carbon material claimed in claim 1.

7. A lithium ion secondary battery comprising:

a positive electrode and a negative electrode capable of storing and releasing lithium ion; and

an electrolyte, wherein said negative electrode is the negative electrode for lithium ion secondary battery claimed in claim 6.