Nanostructured materials for electrochemical conversion reactions
The disclosure is related to battery systems. More specifically, embodiments of the disclosure provide a nanostructured conversion material for use as the active material in battery cathodes. In an implementation, a nanostructured conversion material is a glassy material and includes a metal material, one or more oxidizing species, and a reducing cation species mixed at a scale of less than 1 nm. The glassy conversion material is substantially homogeneous within a volume of 1000 nm 3 .
1. A method of forming a conversion material, the method comprising:
providing a first precursor material, the first precursor material comprising a metal material selected from Fe, Ni, Co, Cu, FeF 3 , FeF 2 , LiFeF 3 , MoO 3 , MoO 2 , or combinations thereof;
providing a second precursor material, the second precursor material comprising a reducing cation material selected from LiF, Li, F 2 , CF 4 , SF 6 , NF 3 , or combinations thereof;
evaporating the first precursor material and the second precursor material to vapor state;
mixing the first precursor material and the second precursor material in the vapor state within a vacuum chamber to form a mixed material within the chamber, the mixed material comprising the first precursor material and the second precursor material mixed at a length scale of less than about 20 nm;
forming an amorphous material by cooling the mixed material at a rate of at least 10 degrees Kelvin per second; and
collecting the amorphous material.
2. The method of claim 1 , wherein the evaporating is performed using a thermal evaporation process, an electron beam process, or a flash evaporation process.
3. The method of claim 1 , wherein the first precursor material and the second precursor material are characterized by a tendency to phase separate.
4. The method of claim 1 , further comprising:
injecting the first precursor material into the chamber from a first nozzle; and
injecting the second precursor material into the chamber from a second nozzle.
5. The method of claim 1 , further comprising:
combining the first precursor material and the second precursor material to form a combined material; and
injecting the combined material into the chamber.
6. The method of claim 1 , wherein the evaporating of the first precursor material and the second precursor material is performed separately.
7. The method of claim 1 , wherein the evaporating is performed at different temperatures for the first precursor material and the second precursor material.
8. The method of claim 1 , wherein the cooling comprises exposing the mixed material to low temperature gaseous species.
9. The method of claim 1 , wherein the evaporating the first precursor material and the second precursor material to vapor state comprises evaporating Fe and LiF.
10. The method of claim 1 , wherein the collecting comprises depositing the amorphous material on an electrolyte disposed on an anode current collector.
11. The method of claim 1 , wherein the mixing comprises depositing alternating layers of the first precursor material and the second precursor material.
12. The method of claim 1 , wherein the conversion material is a positive electrode material comprising:
composite particles or nanodomains comprising:
in the discharged state:
a metal component having a median characteristic length scale of between 3 and 10 nm and selected from the group consisting of iron, cobalt, manganese, copper, nickel, bismuth, and alloys thereof; and
a lithium fluoride compound intermixed with the metal component, wherein substantially all of the lithium fluoride compound is characterized by an amorphous structure; and
in the charged state:
a metal fluoride component selected from the group consisting of iron fluoride, cobalt fluoride, manganese fluoride, copper fluoride, nickel fluoride, bismuth fluoride, and combinations thereof, wherein substantially all of the metal fluoride component is characterized by an amorphous structure.