Method of preparation of carbon materials for use as electrodes in rechargeable batteries
First Claim
1. 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 m2 /g wherein the step-wise heating comprises;
i. heating the stabilized polymer product in an inert atmosphere to about 300°
C. at a rate of less than 5°
C./min;
ii. maintaining the temperature at about 300°
C. for about 2 hours;
iii. raising the temperature to about 370°
C. at a rate of less than 5°
C./min;
iv. maintaining the temperature at about 370°
C. for about 5 hours;
v. raising the temperature from about 370°
C. to at least 800°
C. at a rate less than 5°
C./min;
and vi. maintaining the temperature at least 800°
C. for about 6 hours.
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Accused Products
Abstract
A method of producing carbon materials for use as electrodes in rechargeable batteries. Electrodes prepared from these carbon materials exhibit intercalation efficiencies of ≈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.
104 Citations
16 Claims
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1. A method of producing carbon materials for use as electrodes in rechargeable batteries, comprising the steps of:
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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 m2 /g wherein the step-wise heating comprises; i. heating the stabilized polymer product in an inert atmosphere to about 300°
C. at a rate of less than 5°
C./min;ii. maintaining the temperature at about 300°
C. for about 2 hours;iii. raising the temperature to about 370°
C. at a rate of less than 5°
C./min;iv. maintaining the temperature at about 370°
C. for about 5 hours;v. raising the temperature from about 370°
C. to at least 800°
C. at a rate less than 5°
C./min;and vi. maintaining the temperature at least 800°
C. for about 6 hours. - View Dependent Claims (2, 3, 4)
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5. A method for producing carbon materials capable of intercalating lithium for lithium ion rechargeable batteries, comprising the steps of:
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a) heating and agitating a carbonizable polymer in an inert atmosphere with a pore forming material consisting of urea to form a pretreated product, wherein the carbonizable polymer is selected from the group consisting of homopolymers and co-polymers of polyacrylonitrile, and mixtures and blends thereof; b) heating and agitating the pretreated product in an oxygen-containing atmosphere to form a stabilized polymer product; and c) carbonizing the stabilized polymer product in an inert atmosphere to form a carbon material having BET surface area of less than 10m2 /g and capable of intercalating lithium for lithium ion rechargeable batteries. - View Dependent Claims (6, 7, 8, 9, 10)
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11. A method for producing carbon materials capable of intercalating lithium for lithium-ion rechargeable batteries, consisting essentially of the steps of:
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a) heating and agitating a carbonizable polymer with a pore forming material consisting of urea in an inert atmosphere to form a pretreated product; b) heating and agitating the pretreated product in an oxygen-containing atmosphere to form a stabilized polymer product; and c) carbonizing the stabilized polymer product in an inert atmosphere to form a carbon material capable of intercalating lithium for use in lithium ion rechargeable batteries. - View Dependent Claims (12)
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13. A carbon powder material capable of intercalating lithium for use in lithium ion rechargeable batteries and having a symmetric branched morphology having randomly oriented domains shown by transmission electron microscopy to contain approximately 4 to 10 lattice planes extending approximately 20 to 50 Å
- in the lateral dimension, d002 lattice spacing of about 3.5 to 3.7 Å
, a Raman spectrum showing peaks of near equal height at 1360 cm-1 and 1580 cm-1, a BET surface area of less than 10 m2 /g an average particle size of less than 35 μ
m and a lithium intercalation capacity of at least 50% LiC6 after intercalation with lithium. - View Dependent Claims (14, 15)
- in the lateral dimension, d002 lattice spacing of about 3.5 to 3.7 Å
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16. A method for producing carbon materials capable of intercalating lithium for use in lithium ion rechargeable batteries, comprising the steps of:
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a) heating and agitating a carbonizable polymer in a step-wise manner in an inert atmosphere to form a pretreated product, wherein the carbonizable polymer is in powder form and selected from the group consisting of homopolymers and co-polymers of polyacrylonitrile, and mixtures and blends thereof; b) heating and agitating the pretreated product in a step-wise manner in an oxygen containing atmosphere to form a stabilized polymer product; and c) carbonizing the stabilized polymer product in an inert atmosphere with a pore forming material to form a carbon material capable of intercalating lithium for use in lithium ion rechargeable batteries and having a BET surface area of less than 10 m2 /g.
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Specification