Polymer-sulfur copolymer, method for preparing same, and lithium-sulfur battery comprising same
The present invention relates to a polymer-sulfur copolymer, a preparation method thereof, and a lithium-sulfur battery including the same. In the case of the polymer-sulfur copolymer according to the present invention, since the carrier is polymerized, there is no possibility that the carrier is eluted, and since the sulfur is covalently bonded to the polymer and uniformly distributed in a certain size in the copolymer, when used as a positive electrode active material for the lithium-sulfur battery, the problem of elution of the polysulfide can be improved. In addition, the polymer-sulfur copolymer according to the present invention has a high sulfur impregnation amount, thereby making it possible to realize a high capacity battery.
1. A polymer-sulfur copolymer formed by polymerization of monomers represented by the following formula (1) and elemental sulfur:
wherein,
X is O or S,
Y is H, a C1 to C6 alkyl group or a C6 to C12 aryl group,
Z is a S n H group, a C1 to C6 alkyl group containing at least one S—S bond, or a C6 to C12 aryl group containing at least one S—S bond,
n is an integer of 1 to 6.
2. The polymer-sulfur copolymer according to claim 1 , characterized in that in formula (1),
X is O or S,
Y is H, a C1 to C4 alkyl group or a C6 to C8 aryl group,
Z is SH, S—SH, a C1 to C4 alkyl group containing at least one S—S bond, or a C6 to C8 aryl group containing at least one S—S bond.
3. The polymer-sulfur copolymer according to claim 1 , characterized in that the monomer of formula (1) is at least one selected from the compounds represented by the following formulas (2) to (6):
4. The polymer-sulfur copolymer according to claim 1 , characterized in that the polymer-sulfur copolymer is a copolymer prepared by polymerizing the monomer and elemental sulfur at a weight ratio range of 1:2 to 1:20.
5. The polymer-sulfur copolymer according to claim 1 , characterized in that the polymer-sulfur copolymer has an amorphous crystalline structure.
6. A preparation method of the polymer-sulfur copolymer characterized by comprising;
mixing the monomer represented by the following formula (1) and elemental sulfur to form a mixture;
subjecting the mixture to a first heat treatment to impregnate the liquefied sulfur with monomer;
subjecting the mixture subjected to the first heat treatment to a second heat treatment to copolymerize the monomer and elemental sulfur; and
subjecting the mixture subjected to the second heat treatment to a third heat treatment to perform a vulcanization reaction:
wherein,
X is O or S,
Y is H, a C1 to C6 alkyl group or a C6 to C12 aryl group,
Z is a S n H group, a C1 to C6 alkyl group containing at least one S—S bond, or a C6 to C12 aryl group containing at least one S—S bond,
n is an integer of 1 to 6.
7. The preparation method according to claim 6 , characterized in that the temperature for the first heat treatment is 140 to 170° C.
8. The preparation method according to claim 6 , characterized in that the temperature for the second heat treatment is 170 to 200° C.
9. The preparation method according to claim 6 , characterized in that the temperature for the third heat treatment is 200 to 250° C.
10. A lithium-sulfur battery comprising a positive electrode; a negative electrode; a separator interposed between the positive electrode and the negative electrode; and an electrolyte, characterized in that the positive electrode comprises a polymer-sulfur copolymer according to claim 1 as an active material.