Cathode with coated disordered rocksalt material
A cathode includes a disordered rocksalt phase material and a coating layer disposed on a surface of the disordered rocksalt phase material. The coating layer may include one or more of an oxide, a phosphate, a phosphide, or a fluoride.
1. A cathode comprising:
a disordered rocksalt phase material, and
a coating layer disposed on a surface of the disordered rocksalt phase material, the coating layer comprising one or more of a titanium oxide, a lithium metal phosphate, lithium phosphate, a lithium metal oxide, a phosphide and a fluoride.
2. The cathode of claim 1 , wherein the disordered rocksalt phase material is represented by chemical formula (i):
Li x N y M z O b-a F a (i)
where 1.0<x<1.65; 0≤y<0.55; 0.1<z<1; 0≤a<0.8; 1≤b≤3; N is one of Nb, Ti, Ta, Zr, W, Sb, or Mo; and M is one of Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Al, Zr, Y, Mo, Ru, Rh, or Sb.
3. The cathode of claim 2 , wherein b=2.
4. The cathode of any one of the preceding claims , wherein the coating layer is present at no less than 0.05 wt. % and no greater than 10 wt. % relative to a combined weight of the disordered rocksalt phase material and the coating layer.
5. The cathode of claim 4 , wherein the coating layer is present from 1 to 5 wt. % relative to the combined weight of the disordered rocksalt phase material and the coating layer.
6. The cathode of claim 1 , wherein the coating layer comprises one or more of LiAlO 2 , Li 3 Al 2 (PO 4 ) 3 , Li 3 PO 4 , Li 3 P and Li 2 TiO 3 , TiO 2 .
7. The cathode of claim 6 , wherein the coating layer is comprised of Li 3 PO 4 and Li 3 P.
8. The cathode of claim 1 , wherein the phosphide is a lithium metal phosphide, lithium phosphide or combination thereof.
9. The cathode of claim 8 , wherein the metal of the lithium metal phosphate and lithium metal phosphide is a transition metal.
10. The cathode of claim 9 , wherein said metal is a metal present in the disordered rocksalt.
11. A method for forming a cathode, the method comprising:
mixing a disordered rocksalt phase material with one or more coating precursors to form a mixture, the one or more coating precursors comprising one or more of Al(CH 3 CO 2 ) 3 , a phosphate that decomposes during annealing to form a lithium phosphate or lithium metal phosphate, a lithium phosphide, lithium metal phosphide and TiO 2 ; and
annealing the mixture to form a coated disordered rocksalt powder that has a coating layer disposed on a surface of the disordered rocksalt phase material.
12. The method of claim 11 , wherein the one or more coating precursor is comprised of one or more of a phosphate that decomposes during annealing to form a lithium phosphate or lithium metal phosphate, a lithium phosphide, lithium metal phosphide and TiO 2 and the phosphate decomposes to form Li 3 PO 4 .
13. The method of claim 11 , wherein the phosphate decomposes to form phosphine.
14. The method of claim 11 , wherein during annealing phosphine is present.
15. The method of claim 14 , wherein the phosphine reacts to form a phosphide.
16. The method of claim 11 , wherein the coating layer that is formed comprises one or more of LiAlO 2 , Li 3 Al 2 (PO 4 ) 3 , AlPO 4 , Li 3 PO 4 , Li 3 P, and Li 2 TiO 3 , TiO 2 .
17. The method of claim 11 , wherein the annealing includes heating the mixture at a temperature no less than 200° C. and no greater than 800° C. for a duration no less than 0.5 hours and no more than 24 hours.
18. The method of claim 11 , wherein the annealing includes heating the mixture in an inert gas.
19. The method of claim 11 , further comprising milling the coated disordered rocksalt powder with one or more carbon precursors after the annealing to produce a cathode active material.
20. The method of claim 19 , wherein the carbon precursor is comprised of carbon nanotubes.