Carbon fibers and methods of producing the same

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application Nos. 61/489,585, filed May 24, 2011, the entirety of which is hereby incorporated by reference.

BACKGROUND

Field

The present application relates generally to carbon materials and methods of making of carbon materials. In particular, certain embodiments relate to forming carbon materials from cotton cloth.

Description of the Related Art

Certain classes of carbon fiber and carbon cloth are made using a process which generally starts with a pitch based fiber precursor which is pyrolyzed to the carbon state. The carbon fibers are then formed into a carbon cloth.

SUMMARY

Some embodiments provide a method of manufacturing carbon comprising providing a cotton cloth and pyrolyzing the cotton cloth to form a carbon. In some embodiments, the carbon may comprise carbon cloth. In some embodiments, the cotton cloth is hot pressed prior to pyrolysis.

Some embodiments provide a carbon cloth formed by the method comprising providing a cotton cloth and pyrolyzing the cotton cloth to form a carbon.

Some embodiments provide a carbon cloth comprising carbon formed from pyrolyzing a cotton cloth.

Some embodiments provide a battery comprising the carbon cloth formed by the method comprising providing a cotton cloth and pyrolyzing the cotton cloth to form a carbon. Some embodiments provide a battery comprising the carbon cloth comprising carbon formed from pyrolyzing a cotton cloth.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flow diagram of an example method compatible with certain embodiments described herein.

DETAILED DESCRIPTION

Described herein are carbons (e.g., carbon cloth) and methods to produce carbon that use cotton (e.g., cotton cloth, cotton fabric, cotton weave, etc.) as the precursor. The cotton is pyrolyzed or carbonized to form a carbon (e.g., hard carbon). For example, cotton cloth can be used as a precursor in the making of carbon cloth (e.g., fabric, weave, etc.). FIG. 1 is a flow diagram of an example method 100 compatible with certain embodiments described herein. In operational block 110, a cotton cloth is provided, and in operational block 120, the cotton cloth is pyrolyzed. In certain embodiments, cotton fibers are woven into a cotton cloth, chemically pretreated/stabilized, and then pyrolyzed to form a carbon cloth. Advantages to using cotton as a precursor include, but are not limited to, lower cost and the ability to produce carbon cloth that can be much thinner and lighter per a given area than other carbon cloths that are produced by certain other methods.

In certain embodiments, a very fine cotton cloth is used. For example, the cotton cloth can have a density of about 1 to about 10 mg/cm². In one embodiment, the cotton cloth has a density of about 4.2 mg/cm². The cotton cloth can have a thread count of about 1 to about 100 threads/cm, or about 1 to about 50 threads/cm. In one embodiment, the thread count is about 28 threads/cm. Cotton cloth can be, for example, a weave, knit, intertwine, interlace, etc.

The cotton cloth can be pyrolyzed to form carbon cloth. The cotton cloth can be pyrolyzed by heating the cotton cloth. In one embodiment, the pyrolysis temperature is greater than about 900° C. Pyrolysis can be done in a controlled atmosphere. For example, an inert atmosphere, a vacuum and/or flowing argon, nitrogen, or helium gas can be used. In some embodiments, the cotton cloth is heated to about 800° C. to about 2800° C., about 900° C. to about 1350° C., or about 900° C. to about 1100° C. The dwell time at the pyrolysis temperature can be from about 10 minutes to about 2 hours, or about 30 minutes to about 1 hour. In certain embodiments, the heat up rate and/or cool down rate of the cotton cloth is about 10° C./min. In some embodiments, the cotton cloth is substantially or fully pyrolyzed or carbonized to substantially or completely form carbon. Further description of methods of pyrolysis and carbonization is described in U.S. patent application Ser. No. 13/008,800, filed Jan. 18, 2011, entitled “Composite Materials for Electrochemical Storage,” the entirety of which is hereby incorporated by reference.

In certain embodiments, the cotton cloth is hot pressed prior to pyrolyzing the cotton cloth. In some embodiments, the hot pressing temperature can be from about 200° C. to about 400° C., or about 250° C. to about 350° C. In one embodiment, the temperature that the cotton cloth is hot pressed at is about 300° C. Hot pressing prior to pyrolyzing can stabilize the size and can reduce or prevent shrinking. In some embodiment, the cotton cloth is not hot pressed prior to pyrolysis.

These processes could be batch or continuous in nature. For example, hot pressing the cotton cloth and/or pyrolyzing the cotton cloth can be performed in a continuous process. The cotton cloth can be rolled and unrolled, and fed into machines for processing.

The carbon cloth formed by pyrolysis of the cotton cloth can result in fine texture. In certain embodiments, the carbon cloth has a density of about 0.5 to about 10 mg/cm². In one embodiment, the carbon cloth has a density of about 2.65 mg/cm². The carbon cloth may have a thread count similar to the cotton cloth. Furthermore, in certain embodiments, the carbon cloth has a thickness of about 10 to about 100 microns. For example, the carbon cloth can have a thickness of about 60 microns. Carbon cloth can be, for example, a weave, knit, intertwine, interlace, etc. In some embodiments, the carbon cloth retains the same structure as the cotton cloth prior to pyrolysis.

The resulting carbon cloth can be electrically conductive and has a good electrical conductivity. The carbon cloth is also very lightweight. Furthermore, the carbon cloth can be used both as a structural component and as a conductive additive in application. For example, the carbon cloth can be used as a carbon material or carbon phase in the composite materials described in U.S. patent application Ser. No. 13/008,800. The carbon cloth can even be used where the resulting composite is desired to be very thin.

Without being bound by theory, the relatively high cellulose content in cotton cloth may provide a carbon cloth. Therefore, the cotton can be natural cotton or synthetically made from cellulose. In certain embodiments, the cotton cloth has a cellulose concentration greater than about 90% by weight.

Various embodiments have been described above. Although the invention has been described with reference to these specific embodiments, the descriptions are intended to be illustrative and are not intended to be limiting. Various modifications and applications may occur to those skilled in the art without departing from the true spirit and scope of the invention as defined in the appended claims.