US 5,882,621 A · Method of preparation of carbon materials for use as electrodes in rechargeable batteries

Abstract

A method of producing carbon materials for use as electrodes in rechargeable batteries. Electrodes prepared from these carbon materials exhibit intercalation efficiencies of .apprxeq.80% for lithium, low irreversible loss of lithium, long cycle life, are capable of sustaining a high rates of discharge and are cheap and easy to manufacture. The method comprises a novel two-step stabilization process in which polymeric precursor materials are stabilized by first heating in an inert atmosphere and subsequently heating in air. During the stabilization process, the polymeric precursor material can be agitated to reduce particle fusion and promote mass transfer of oxygen and water vapor. The stabilized, polymeric precursor materials can then be converted to a synthetic carbon, suitable for fabricating electrodes for use in rechargeable batteries, by heating to a high temperature in a flowing inert atmosphere.

Claims16

Dependent claims

A method of producing carbon materials for use as electrodes in rechargeable batteries, comprising the steps of:

a) heating a carbonizable polymer material selected from the group consisting of polyacrylonitrile, co-polymers of polyacrylonitrile and mixtures thereof in a step-wise manner at a fixed rate of heating to a temperature in an inert atmosphere while simultaneously agitating the polymer material to form a pretreated product;
b) cooling the pretreated product;
c) heating the pretreated product in an oxygen containing atmosphere in a step-wise manner at a fixed rate of heating to a temperature while simultaneously agitating the pretreated product to form a stabilized polymer product;
d) carbonizing the stabilized polymer product by heating in a step-wise manner to a temperature in an inert atmosphere, thereby forming a carbon material having a surface area of less than 10 m.sup.2 /g wherein the step-wise heating comprises:
i. heating the stabilized polymer product in an inert atmosphere to about 300.degree. C. at a rate of less than 5.degree. C./min;
ii. maintaining the temperature at about 300.degree. C. for about 2 hours;
iii. raising the temperature to about 370.degree. C. at a rate of less than 5.degree. C./min;
iv. maintaining the temperature at about 370.degree. C. for about 5 hours;
v. raising the temperature from about 370.degree. C. to at least 800.degree. C. at a rate less than 5.degree. C./min;
and vi. maintaining the temperature at least 800.degree. C. for about 6 hours.

7 more elements

Dependencies are inferred from the claim text.

Method of preparation of carbon materials for use as electrodes in rechargeable batteries

Life of this patent

Method of preparation of carbon materials for use as electrodes in rechargeable batteries

Life of this patent

Abstract

Claims16