Preparation of high energy capacity ruthenium oxide

• US 6,025,020 A
• Filed: 10/08/1997
• Issued: 02/15/2000
• Est. Priority Date: 10/08/1997
• Status: Expired due to Fees

• Current Assignee: Auburn University
• Original Assignee: Auburn University
• Inventors: Chen, Zheng, Rose, Millard Franklin
• Primary Examiner(s): King, Roy V.
• Application Number:
  US08/947,267
• Time in Patent Office: 860 Days
• Field of Search: 361/314, 361/315, 361/321.1, 361/321.5, 361/303, 361/324, 427/79, 427/226, 427/126.3, 427/113
• US Class Current: 427/226
• CPC Class Codes: C01G 55/004 Oxides; Hydroxides
• CPC Class Codes: C01P 2002/02 Amorphous compounds
• CPC Class Codes: C01P 2006/80 Compositional purity

Abstract

Amorphous, highly dispersed ruthenium oxide having a high energy storage capacity may be prepared using high surface area carbon as carbon powder or as carbon fibers as a template for the ruthenium oxide. The process avoids the disadvantages of a sol-gel process, and utilizes deposition of a ruthenium source within the pores of carbon fibers dispersed in a cellulose matrix. The ruthenium source subsequently is converted to amorphous ruthenium oxide hydrate by heating in a steam atmosphere containing at least 30 weight percent water at temperatures up to about 500° C.

Claims

1. A process for the preparation of an amorphous ruthenium oxide composite comprising:

a. impregnating high surface area carbon fibers dispersed in a cellulose matrix with an aqueous solution of a ruthenium source;

b. drying the matrix of ruthenium source impregnated carbon fibers at a temperature sufficient to remove water;

c. heating the dried matrix of impregnated carbon fibers in a steam and oxygen atmosphere containing at least 30 weight percent water at a temperature up to about 500°

C. for a time sufficient to convert the ruthenium source to amorphous ruthenium oxide hydrate; and

d. recovering as said composite the amorphous ruthenium oxide hydrate impregnated on high surface area carbon fibers dispersed in a cellulose matrix.

2. The process of claim 1 where the cellulose matrix contains from about 50 to about 90 weight percent high surface area carbon fibers.

3. The process of claim 1 where the carbon fibers have a surface area of at least about 200 square meters per gram.

4. The process of claim 1 where the ruthenium source is a ruthenium halide.

5. The process of claim 1 where the steam atmosphere contains from about 30 up to about 80 weight percent water.

6. The process of claim 1 where the dried matrix of the ruthenium-impregnated carbon fibers is heated at a temperature between about 420 up to about 475°

C.

7. The process of claim 1 further characterized in that the amorphous ruthenium oxide hydrate impregnated on high surface area carbon fibers dispersed in a cellulose matrix is subsequently heated in a dried atmosphere at a temperature between about 100 to about 150°

C. for a time effective to produce RuO₂.xH₂ O with the desired degree of hydration.

8. The process of claim 1 where said composite contains from about 20 up to about 40 weight percent ruthenium oxide based on total composite.

9. The process of claim 1 further characterized in that the amorphous ruthenium oxide composite is subsequently heated in air at a temperature above about 350°

C. for a time effective to convert the amorphous ruthenium oxide in said composite to a crystalline state.