Core-shell structured nanoparticles for lithium-sulfur cells
Described is a core-shell nanoparticle comprising a lithium sulfide nanoparticle core and a shell covering the lithium sulfide nanoparticle core. The core-shell nanoparticle may be used for a positive electrode in a lithium/sulfur battery cell.
1. A core-shell nanoparticle comprising:
a lithium sulfide nanoparticle core that is non-hollow; and
a shell conformally coated directly on the lithium sulfide nanoparticle core, the shell comprising an electronically conducting polymer.
2. The core-shell nanoparticle of claim 1 , wherein the lithium sulfide nanoparticle core has a substantially spherical shape.
3. The core-shell nanoparticle of claim 1 , wherein the lithium sulfide nanoparticle core has a shape selected from the group consisting of: ovals, crystals, wires, columns, and boxes.
4. The core-shell nanoparticle of claim 1 , wherein the core-shell nanoparticle has a diameter of approximately 200-300 nanometers.
5. The core-shell nanoparticle of claim 4 , wherein the lithium sulfide nanoparticle core is convertible into a single sulfur nanoparticle core having a reduced diameter, and wherein the core-shell nanoparticle retains the diameter of approximately 100-300 nanometers after the lithium sulfide nanoparticle core is converted into the single sulfur nanoparticle core.
6. The core-shell nanoparticle of claim 3 , wherein the core shell particle maintains approximately its original shape after the lithium sulfide nanoparticle core is converted into a single sulfur nanoparticle core.
7. The core-shell nanoparticle of claim 1 , wherein a thickness of the shell is approximately 1-10 nanometers.
8. The core-shell nanoparticle of claim 1 , wherein a thickness of the shell is thicker than a few nanometers.
9. The core-shell nanoparticle of claim 1 , wherein the polymer comprises polyaniline.
10. The core-shell nanoparticle of claim 9 , wherein the polyaniline shell has been heated.
11. The core-shell nanoparticle of claim 9 , wherein the polyaniline shell has been heated to a temperature of 400-500° C.
12. The core-shell nanoparticle of claim 1 , wherein the polymer comprises a polymer other than polyaniline.
13. The core-shell nanoparticle of claim 1 , wherein the polymer is a lithium ion conductor.
14. The core-shell nanoparticle of claim 7 , wherein a thickness of the shell is approximately 1-2 nanometers.
15. A mixture comprising core-shell nanoparticles of claim 1 , in combination with a binder and an organic solvent.
16. The mixture of claim 15 , further comprising a material selected from the group consisting of: carbon, carbon nanofibers, and other conductive agents.
17. The mixture of claim 15 wherein the mixture is a slurry.
18. A positive electrode composition comprising an electrical conductor coated with the mixture of claim 15 .
19. A Li/S battery cell comprising:
the positive electrode composition of claim 18 ;
an electrolyte; and
a negative electrode.