Sulfur-modified polyacrylonitrile, manufacturing method therefor, and application thereof
Provided is a sulfur-modified polyacrylonitrile manufacturing method that is characterized in that a starting base powder that comprises sulfur powder and polyacrylonitrile powder is mixed and the mixture is heated in a non-oxidizing environment while outflow of sulfur vapor is prevented. Also provided are a cathode for lithium batteries that uses, as the active substance, the sulfur-modified polyacrylonitrile manufactured with the method, and a lithium secondary battery that includes the cathode as a component element. This enables the practical use of an inexpensive sulfur-based material as the cathode material for lithium secondary batteries, and in particular, a sulfur-based cathode material that enables higher output and has excellent cycle life characteristics, as well as other characteristics, and secondary lithium batteries using the same can be obtained.
1. A method of manufacturing sulfur-modified polyacrylonitrile, comprising:
mixing a base powder comprising sulfur powder and polyacrylonitrile powder;
heating the base powder to a temperature of from 250 to 500 degree Celsius under a nonoxidative atmosphere while preventing the effluence of sulfur vapor to obtain a crude sulfur-modified polyacrylonitrile;
cooling the crude sulfur-modified polyacrylonitrile; and
heating the cooled crude sulfur-modified polyacrylonitrile to a temperature of from 150 to 400 degree Celsius under a nonoxidative atmosphere to obtain a sulfur-modified polyacrylonitrile.
2. The method according to claim 1 , wherein the base powder is heated in a closed atmosphere.
3. The method according to claim 1 , wherein the base powder is heated while refluxing sulfur vapor in a reaction container having an opening for discharging hydrogen sulfide produced by a reaction.
4. The method according to claim 1 , wherein the base powder further includes an auxiliary conductivity agent made of a high crystallinity carbon material.
5. The method according to claim 1 , wherein the sulfur-modified polyacrylonitrile has a Raman spectrum having a major peak in the vicinity of 1331 cm −1 of Raman shift, and has other peaks in the vicinity of 1548 cm −1 , 939 cm −1 , 479 cm −1 , 381 cm −1 , 317 cm −1 in a Raman shift range of 200 cm −1 ˜1800 cm −1 .
6. A method of manufacturing a cathode for a lithium secondary battery, comprising:
charging a base powder comprising sulfur powder and polyacrylonitrile powder in a collector made of a porous material; and
heating the base powder to a temperature of from 250 to 500 degree Celsius under a nonoxidative atmosphere while preventing the effluence of sulfur vapor to obtain a crude sulfur-modified-modified polyacrylonitrile;
cooling the crude sulfur-modified polyacrylonitrile; and
heating the cooled crude sulfur-modified polyacrylonitrile to a temperature of from 150 to 400 degree Celsius under a nonoxidative atmosphere to obtain a cathode comprising sulfur-modified polyacrylonitrile.
7. The method according to claim 6 , wherein the collector made of a porous material is a nonwoven or woven fabric made of a carbon material having high degree of graphitization.
8. The method according to claim 6 , wherein the base powder further includes an auxiliary conductivity agent made of a high-crystallinity carbon material.
9. The method according to claim 1 , wherein the sulfur-modified polyacrylonitrile is cooled to room temperature.