Selenium-doped sulfur cathodes for rechargeable batteries
View Patent ↗An electrochemical device includes an anode, a separator, a cathode comprising a selenium-doped sulfur/carbon composite that includes a conductive carbon matrix and nano-sized selenium-doped sulfur particles of formula S x Se y , where a ratio of x:y is from 2.5 to 1000, and an electrolyte comprising a salt and a non-aqueous fluorinated ether solvent.
1. An electrochemical device comprising:
a cathode comprising a selenium-doped sulfur (S x Se y )/carbon composite;
a lithium anode or a sodium anode;
a separator; and
an electrolyte comprising:
a salt; and
a non-aqueous, fluorinated ether solvent selected from the group consisting of 1,1,2,2-tetrafluoroethyl-2,2,3,3,3-pentafluoropropyl ether; 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether; 2,2,2-trisfluoroethyl-1,1,2,3,3,3-hexafluoropropyl ether; 1,1,1,3,3,3-hexafluoro-2-propyl ether; ethyl-1,1,2,3,3,3-hexafluoropropyl ether; difluoromethyl-2,2,3,3,3-pentafluoropropyl ether; and difluoromethyl-2,2,3,3-tetrafluoropropyl ether;
wherein:
the salt is present in the non-aqueous, fluorinated ether solvent at a concentration from about 0.01 M to about 2.0 M;
the selenium-doped sulfur (S x Se y )/carbon composite comprises:
a conductive carbon matrix; and
nano-sized selenium-doped sulfur particles;
a ratio of x:y is from 2.5 to 1000.
2. The electrochemical device of claim 1 , wherein:
the nano-sized selenium-doped sulfur particles are uniformly dispersed on the surface of the conductive carbon matrix; and
the conductive carbon matrix comprises graphite, graphene, expanded graphite, reduced graphene oxide, acetylene black, carbon black, a metal-organic framework, porous carbon, carbon spheres, or carbon aerogel, single-walled carbon nanotubes, multi-walled carbon nanotubes, carbon nanofibers, carbon nanotube arrays, polypyrrole, or polyaniline.
3. The electrochemical device of claim 1 , wherein:
the conductive carbon matrix is a porous conductive carbon matrix;
the nano-sized selenium-doped sulfur particles are uniformly within pores of the porous conductive carbon matrix; and
the conductive carbon matrix comprises graphite, graphene, expanded graphite, reduced graphene oxide, acetylene black, carbon black, a metal-organic framework, porous carbon, carbon spheres, or carbon aerogel, single-walled carbon nanotubes, multi-walled carbon nanotubes, carbon nanofibers, carbon nanotube arrays, polypyrrole, or polyaniline.
4. The electrochemical device of claim 1 , wherein the non-aqueous fluorinated ether solvent is 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether.
5. The electrochemical device of claim 1 , wherein the electrolyte further comprises a non-fluorinated co-solvent.
6. The electrochemical device of claim 1 that is a lithium battery.
7. The electrochemical device of claim 1 that is a sodium battery.
8. The electrochemical device of claim 1 , wherein the salt is present in the non-aqueous, fluorinated ether solvent at a concentration from about 0.01 M to about 1.5 M.
9. The electrochemical device of claim 1 , wherein the salt is present in the non-aqueous, fluorinated ether solvent at a concentration from about 0.01 M to about 1.0 M.