Carbonaceous active material and method of making same

• US 5,830,602 A
• Filed: 02/20/1997
• Issued: 11/03/1998
• Est. Priority Date: 02/20/1997
• Status: Expired due to Fees

• Current Assignee: Valence Technology Incorporated (Lithium Werks B.V.)
• Original Assignee: Valence Technology Incorporated (Lithium Werks B.V.)
• Inventors: Barker, Jeremy, Koksbang, Rene
• Primary Examiner(s): KALAFUT, STEPHEN J
• Application Number:
  US08/802,977
• Time in Patent Office: 621 Days
• Field of Search: 205/414, 205/419, 205/422, 205/423, 205/427, 423/415.1, 423/449.6, 429/218
• US Class Current: 429/218.1
• CPC Class Codes: H01M 10/052 Li-accumulators
• CPC Class Codes: H01M 10/0564 the electrolyte being constituted of organic materials only
• CPC Class Codes: H01M 4/587 for inserting or intercalating light metals
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

The present invention provides an electrochemical cell or battery which has a non-metallic negative electrode (anode). That is, no solid metal, free metal, active material is used in the cell. Rather than the conventional solid lithium metal anode, the active material of the new electrode comprises substituted carbon active material. The substituted carbon is carbonaceous material arranged in a disordered or ordered graphite structure, where atoms of carbon have been substituted in such structure by at least one other element. The invention also provides carbonaceous materials which are non-graphitic and considered amorphous, non-crystalline, highly disordered, which also have substituted therein elements other than carbon. The invention also provides a process for making such substituted carbons and for preparing an anode containing the substituted carbon.

Claims

1. A method for producing a carbonaceous material which has a dopant element different from carbon, comprising:

a. providing vinyl monomers having the general formula;

##STR3## where G represents a pendant group comprising at least one element which is different from carbon;

b. electro-polymerizing said vinyl monomers to form a polymer; and

c. heating said polymer to pyrolize the polymer thereby forming a carbonaceous material which includes said at least one element, with carbon constituting the largest portion by weight of said carbonaceous material and said at least one element constituting the second largest portion.

2. The method according to claim 1 wherein said at least one element is selected from the group consisting of N, O, and elements adjacent to elements C, N, and O in Columns 13 through 16 of the Periodic Table.

3. The method according to claim 1 wherein the G group is a heterocyclic hydrocarbon ring compound.

4. The method according to claim 1 wherein the G group is a nitrogen, sulfur, phosphorous, or oxygen heterocyclic hydrocarbon ring structure.

5. The method according to claim 1 wherein the vinyl monomer is selected from the group consisting of vinyl heterocyclic compounds, vinylsilane compounds, vinyl hydronitrogen compounds, and vinyl hydrofuran compounds.

6. The method according to claim 1 wherein the vinyl monomer is selected from the group consisting of vinyltri(methyl)silane;

vinyltri(phenyl)silane;

dl-vinylglycine;

L-vinylglycine;

vinyl sulfone;

1-vinyl-2-pyrrolidinone;

vinyltri(methoxy)silane;

vinyltri(chloro)silane;

2-vinylpyridine;

4-vinylpyridine;

vinylphthalimide;

vinyl propionate;

2-vinyl-1-pyrazine;

vinylimidazole; and

mixtures thereof.

7. The method according to claim 1 wherein the heating occurs at a temperature which provides said carbonaceous material in an amorphous condition.

8. The method according to claim 1 wherein the heating occurs at a temperature which provides said carbonaceous material in the form of non-graphitic carbon black or coke.

9. The method according to claim 1 wherein the heating occurs at a temperature which provides said carbonaceous material in the form of graphite having fused carbon ring structures arranged in layers.

10. The method according to claim 1 wherein the heating occurs at a temperature less than 2000°

C. to form a disordered non-graphite carbon.

11. The method according to claim 1 wherein the heating occurs for about 2 hours at a temperature in excess of about 2400°

C. to form a graphitized relatively ordered graphite carbon.

12. The method according to claim 1 wherein said electro-polymerizing is conducted by:

i. providing a working electrode opposite a counter-electrode in an electrochemical cell containing an electrolyte solution consisting essentially of an organic solvent and an electrolyte salt which does not contain a metal species; and

ii. impressing a current across the cell at a potential sufficient to electrochemically oxidize said vinyl monomer to a polymer and deposit said polymer on a surface of said working electrode.

13. The method according to claim 12 wherein said organic solvent is acetonitrile and said salt is an organic salt which, in said solvent, forms a positively charged organic species (cation) and a PF₆ (anion).

14. The method according to claim 12 wherein said monomer is vinylpyridine.

15. A method for increasing the lithium insertion capacity of a carbon active material selected from the group consisting of disordered carbon, carbon black, coke, and graphitized carbon, said method comprising substituting atoms of an element E for a minor portion of carbon atoms in said carbon active material, said portion being less than 50 percent of said carbon atoms;

said element E being bonded to at least 1 carbon atom in said carbon active material and being selected from the group consisting of N, O, and elements adjacent to elements C, N, and O in Columns 13 through 16 of the Periodic Table, provided said element E is an electron donor;

said substituted carbon characterized by greater lithium insertion capacity as compared to unsubstituted carbon active material.

16. A method for increasing the lithium insertion capacity of a carbon active material selected from the group consisting of disordered carbon, carbon black, coke, and graphitized-carbon, said method comprising:

a. providing vinyl monomers having the general formula;

##STR4## where G represents a pendant group comprising at least one element which is different from carbon;

b. electro-polymerizing said vinyl monomers to form a polymer;

c. heating said polymer to pyrolize the polymer thereby forming a carbonaceous material which includes said at least one element, said element substituted for a minor portion of carbon atoms in said carbonaceous material, with carbon constituting the largest portion by weight of said carbonaceous material and said at least one element constituting the second largest portion;

d. forming an anode electrode by mixing said substituted carbonaceous material with a binder and applying said mixture to a current collector; and

e. assembling a battery comprising said anode electrode, a counter-electrode forming an electrochemical couple with said anode, and an electrolyte disposed between said anode and said counter-electrode.

17. A lithium ion battery comprising a positive electrode, an electrolyte, and a negative electrode, said negative electrode comprising an electro-active graphite-structured material formed by carbon atoms wherein atoms of element E have been substituted for a minor portion of said carbon atoms of said graphite structure, said element E being selected from the group consisting of N, O, and elements adjacent to elements C, N, and O in Columns 13 through 16 of the Periodic Table, provided said element E is an electron donor.

18. The lithium ion battery according to claim 17 wherein said electron donor element is selected from the group consisting of N, O, Si, S, P, and mixtures thereof.