Disordered rocksalt cathode material and method of making it
It has been discovered that improved disordered rocksalts comprise of Mn are made by method comprising mixing a lithium compound with a metal precursor compound comprised of Mn having an oxidation state of 2 to form a mixture and heating the mixture to a temperature to form a disordered rocksalt structure. The method may realize improved cycle life with altered metal and oxygen redox of the disordered rocksalt.
1. A method comprising:
mixing a lithium compound with a metal precursor compound comprised of Mn having an oxidation state of 2, wherein at least 50% by weight of the Mn has an oxidation state of 2 to form a mixture and heating the mixture to a temperature to form a disordered rocksalt.
2. The method of claim 1 , wherein the metal precursor is comprised of MnO.
3. The method of claim 1 , wherein the metal precursor compound is a mixed metal oxide intermediate comprised of Mn having the 2 oxidation state, said mixed metal oxide being formed by a method comprising:
mixing a Mn compound having an oxidation state greater than 2 with at least one other metal precursor compound to a temperature to form an intermediate precursor mixture,
and heating the intermediate precursor mixture in an intermediate atmosphere in the absence of lithium to an intermediate temperature to form the mixed metal oxide intermediate comprised of Mn having the 2 oxidation state.
4. The method of claim 3 , wherein the Mn compound having an oxidation state of greater than 2 is Mn 2 O 3 .
5. The method of claim 3 , wherein the intermediate atmosphere is air.
6. The method of claim 3 , wherein the intermediate temperature is from 500° C. to 1200° C. and the intermediate temperature is held for a time from 10 minutes to 24 hours.
7. The method of claim 6 , wherein the temperature is held at two or more differing temperatures.
8. The method of claim 1 , wherein the heating is performed in an atmosphere essentially devoid of oxygen.
9. The method of claim 1 , wherein the mixing of the lithium compound and metal precursor compound comprises comminuting the lithium compound and metal precursor compound together.
10. The method of claim 1 , wherein the disordered rocksalt having a formula (i):
Li x N y M z O 2-a F a (i)
where 1.0<x<1.65; 0≤y<0.55; 0.1<z<1; 0≤a<0.5; N is one of Ti, Ta, Zr, W, Nb, or Mo; and M is Mn and one or more of Ti, V, Cr, Fe, Co, Ni, Cu, Zn, Al, Zr, Y, Mo, Ru, Rh, Sn, Bi or Sb.
11. A disordered rocksalt having a metal redox capacity and an oxygen redox capacity, wherein the metal redox capacity is greater than the oxygen redox capacity and the disordered rocksalt is comprised of Mn and at least 50% by weight of the Mn is present in the 2+ valence state.
12. The disordered rocksalt of claim 11 , wherein the metal redox capacity is at least 10% greater than the oxygen redox capacity.
13. The disordered rocksalt of claim 11 , wherein the disordered rocksalt having a formula (i):
Li x N y M z O 2-a F a (i)
where 1.0<x<1.65; 0≤y<0.55; 0.1<z<1; 0≤a<0.5; N is one of Ti, Ta, Zr, W, Nb, or Mo; and M is Mn and one or more of Ti, V, Cr, Fe, Co, Ni, Cu, Zn, Al, Zr, Y, Mo, Ru, Rh, Sn, Bi or Sb.
14. The disordered rocksalt of claim 13 , wherein “a” is zero.
15. The disordered rocksalt of claim 13 , wherein N is Nb and M is Mn and Ti and Mn and Ti are each present in an amount such that Mn/Ti in moles is 1 to 10.
16. A cathode comprised of the disordered rocksalt of claim 11 .
17. The cathode of claim 16 , further comprised of carbon wherein the disordered rocksalt and carbon are each present in an amount such that the amount of disordered rocksalt/amount of the carbon by weight is a ratio of 100/1 to 1.5/1.
18. A composition comprising a disordered rocksalt comprised of Li, Mn, and O, wherein at least 50% by weight of the Mn present is in a 2+ valence state.
19. The composition of claim 18 , wherein at least 75%, by weight of the Mn present is in the 2+ valence state.
20. The composition of claim 18 , wherein the disordered rocksalt having a formula (i):
Li x N y M z O 2-a F a (i)
where 1.0<x<1.65; 0≤y<0.55; 0.1<z<1; 0≤a<0.5; N is one of Ti, Ta, Zr, W, Nb, or Mo; and M is Mn and one or more of Ti, V, Cr, Fe, Co, Ni, Cu, Zn, Al, Zr, Y, Mo, Ru, Rh, Sn, Bi or Sb.