Rechargeable lithium cell and process for making an anode for use in the cell

• US 5,545,468 A
• Filed: 03/16/1994
• Issued: 08/13/1996
• Est. Priority Date: 03/17/1993
• Status: Expired due to Term

• Current Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Koshiba, Nobuharu, Asaka, Emi, Nakanishi, Makoto, Takata, Kenichi
• Primary Examiner(s): NUZZOLILLO, MARIA
• Application Number:
  US08/213,900
• Time in Patent Office: 881 Days
• Field of Search: 429/218, 429/194, 429/197, 429/129, 423/138, 423/179.5
• US Class Current: 429/231.1
• 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 2300/0025 Organic electrolyte
• CPC Class Codes: H01M 4/131 Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
• CPC Class Codes: H01M 4/1391 of electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
• CPC Class Codes: H01M 4/485 of mixed oxides or hydroxides for inserting or intercalating light metals, e.g. LiTi2O4 or LiTi2OxFy H01M4/505, H01M4/525 take precedence
• CPC Class Codes: H01M 4/505 of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy
• CPC Class Codes: H01M 4/525 of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
• 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

A rechargeable lithium cell comprises a cathode having a discharge potential not less than 2 V relative to a Li/Li⁺ anode, an anode capable of doping and un-doping lithium and made of a material comprising a lithium titanate having a spinel structure and represented by the general formula, LixTiyO₄ wherein 0.8≦x≦1.4 and 1.6≦y≦2.2, a separator separating the cathode and the anode from each other, and an electrolytic solution impregnated at least in the separator and dissolving a lithium salt in a non-aqueous solvent. When subjected to X-ray diffraction analysis, the material has peaks at least at 4.84±0.02 angstroms, 2.53±0.02 angstroms, 2.09±0.02 angstroms and 1.48±0.02 angstroms and a ratio of a peak intensity at 4.84±0.02 angstroms and a peak intensity at 1.48±0.02 angstroms of 100:30±10. The material may consist of the lithium titanate or mixed crystals of the lithium titanate and rutile-type titanium dioxide. A process for making the anode is also described.

Claims

1. A rechargeable lithium cell which comprises a cathode which has a discharge potential not less than 2 V relative to a Li/Li⁺ anode, an anode capable of doping and un-doping lithium comprising a lithium titanate which has a spinel structure and is a final product having the general formula, Li_x Ti_y O₄, wherein 0.8≦

x≦

1.4 and 1.6≦

y≦

2.2, a separator separating the cathode and the anode from each other, and an electrolytic solution impregnated at least in the separator and containing a lithium salt dissolved in a non-aqueous solvent, wherein when subject to X-ray diffraction analysis using a Cu target, said reaction product has diffraction peaks at least at 4.84±

0.02 angstroms, 2.53±

0.02 angstroms, 2.09±

0.02 angstroms and 1.48±

0.02 angstroms and a ratio of a peak intensity at 4.84±

0.02 angstroms and a peak intensity at 1.48±

0.02 angstroms of 100;

30±

10.

2. The cell according to claim 1, wherein said anode consists essentially of the lithium titanate which has a spinel structure and is represented by the general formula, LixTiyO₄, wherein 0.8≦

x≦

1.4 and 1.6≦

y≦

2.2.

3. The cell according to claim 2, wherein said lithium titanate consists essentially of LiTi₂ O₄.

4. The cell according to claim 2, wherein said lithium titanate consists essentially of Li_4/3 Ti_5/3 O₄.

5. The cell according to claim 2, wherein said lithium titanate consists essentially of Li₀.8 Ti₂.2 O₄.

6. The cell according to claim 1, wherein said lithium salt in said electrolytic solution is a member selected from the group consisting of LiPF₆, LiCF₃ SO₃, LiBF₄, LiClO₄, LiN(CF₃ SO₂)₂ and mixtures thereof.

7. A rechargeable lithium cell which comprises:

a cathode which has a discharge potential not less than 2 V relative to a Li/Li⁺ anode;

an anode capable of doping and un-doping lithium comprising mixed crystals of a lithium titanate which has a spinel structure and is a final product having the general formula, Li_x Ti_y O₄, wherein 0.8≦

x≦

1.4 and 1.6≦

y≦

2.2 and rutile form of titanium dioxide;

a separator separating the cathode and the anode from each other; and

an electrolytic solution impregnated at least in the separator and containing a lithium salt dissolved in a non-aqueous solvent, wherein when subjected to X-ray diffraction analysis using a Cu target, said final product has diffraction peaks at least at 4.84±

0.02 angstroms, 3.25±

0.02 angstroms, 2.53±

0.02 angstroms, 2.49±

0.02 angstroms, 2.19±

0.02 angstroms, 2.09±

0.02 angstroms, 1.69±

0.02 angstroms, and 1.48±

0.02 angstroms.

8. The cell according to claim 7, wherein said anode consists essentially of said mixed crystals.

9. The cell according to claim 7, wherein said lithium titanate and said rutile form at titanium oxide coexist in one mixed crystal.

10. The cell according to claim 7, wherein said final product has a ratio of a peak intensity at 4.84±

0.02 angstroms and a peak intensity at 1.48±

0.02 angstroms of 100;

30±

10 and ratios of a peak intensity at 3.25±

0.02 angstroms, a peak intensity at 2.58±

0.02 angstroms and a peak intensity at 1.69±

0.02 angstroms of 100;

50±

10;

60±

10.

11. The cell according to claim 7, wherein said lithium titanate consists essentially of LiTi₂ O₄.

12. The cell according to claim 7, wherein said lithium titanate consists essentially of Li_4/3 Ti_5/3 O₄.

13. The cell according to claim 7, wherein said lithium salt in said electrolytic solution is a member selected from the group consisting of LiPF₆, LiCF₃ SO₃, LiBF₄, LiClO₄, LiN(CF₃ SO₂)₂ and mixtures thereof.