Polycrystalline metal oxide, methods of manufacture thereof, and articles comprising the same

1. A particle, comprising:

a plurality of crystallites comprising a first composition having a layered α-NaFeO 2 -type structure and comprising:

lithium, nickel, and oxygen;

a grain boundary between adjacent crystallites of the plurality of crystallites and comprising a second composition having the layered α-NaFeO 2 -type structure, a cubic structure, or a combination thereof,

wherein a concentration of cobalt in the grain boundary is greater than a concentration of cobalt in the crystallites.

2. The particle of claim 1 , wherein the grain boundary is substantially rectilinear in cross-section.

3. The particle of claim 1 , wherein a direction of a surface of the grain boundary is different than a direction of a tangent of a nearest outer surface of the particle.

4. The particle of claim 1 , wherein the particle comprises a first grain boundary and a second grain boundary, wherein the first grain boundary and the second grain boundary are each directly on a same crystallite of the plurality of crystallites, and wherein the first grain boundary and second grain boundary intersect at an angle determined by a crystal structure of the first composition.

5. The particle of claim 1 ,

having an average grain boundary length of about 50 to about 1000 nanometers,

having an average grain boundary thickness of about 1 to about 200 nanometers,

wherein the grain boundary has a length of about 50 to about 1000 nanometers, wherein the length is parallel to a surface of an adjacent crystallite, and

wherein the grain boundary has a thickness of about 1 to about 200 nanometers, wherein the thickness is perpendicular to the crystallite surface.

6. The particle of claim 1 , wherein

the second composition comprises

lithium in an amount of about 0.1 to about 1.3 moles, per mole of the second composition,

nickel in an amount of about 0.1 to about 1 mole, per mole of the second composition,

cobalt in an amount of about 0.02 to about 0.99 mole, per mole of the second composition, and

oxygen in an amount of about 1.7 to about 2.3 moles, per mole of the second composition.

7. The particle of claim 1 , wherein

the first composition may further comprise an additional metal, wherein the additional metal of the first composition is present in an amount of about 0.01 to about 0.9 mole, per mole of the first composition;

the second composition further comprises an additional metal, wherein the additional metal of the second composition is present in an amount of about 0.01 to about 0.9 mole, per mole of the second composition; and

the additional metal of the first and second compositions each independently comprise Mg, Sr, Ca, Cu, Zn, Mn, Al, V, Ba, Zr, Ti, Cr, Fe, Mo, B, or a combination thereof.

8. The particle of claim 1 or 7 , wherein the first composition further contains cobalt, with the cobalt concentration in the range of 0 to about 0.5 mole per mole of the first composition.

9. The particle of claim 8 wherein the first composition further contains cobalt, with the cobalt concentration in the range of 0.0 to about 0.3 mole per mole of the first composition.

10. The particle of claim 9 , wherein said first composition comprises nickel at a concentration of 0.8 to 1 moles per mole of said first composition.

11. The particle of claim 1 , wherein

the first composition comprises Mn, and the Mn is present in the first composition in an amount of about 0.01 to about 0.6 mole, per mole of the first composition, and

the second composition comprises Mn, and the Mn is present in the second composition in an amount of about 0.01 to about 0.6 mole, per mole of the second composition.

12. The particle of claims 1 or 7 , wherein said first composition comprises nickel at a concentration of 0.8 to 1 moles per mole of said first composition.

13. The particle of claim 12 wherein said first composition comprises nickel at a concentration of 0.92 moles per mole of said first composition.

14. The particle of claim 1 or 7 wherein the first composition comprises:

lithium in an amount of about 0.1 to about 1.3 moles, per mole of the first composition;

nickel in an amount of about 0.1 to about 0.99 mole, per mole of the first composition; and

cobalt in an amount of 0 to about 0.5 mole, per mole of the first composition.

15. The particle of claim 1 or 7 wherein

a concentration of cobalt in the crystallites is about 0.25 to about 17 atomic percent, and

a concentration of cobalt in the grain boundary is about 0.5 to about 32 atomic percent, each based on a total atomic composition of the particle.

16. The particle of claim 1 , further comprising a layer on a surface of the particle, wherein the layer comprises an oxide, a phosphate, a pyrophosphate, a fluorophosphate, a carbonate, a fluoride, an oxyfluoride, or a combination thereof, of Zr, Li, Al, Ti, B, or Si, or a combination thereof.

17. A method of manufacturing the particle of claim 1 , the method comprising:

combining a lithium compound, a cobalt compound, and a nickel compound to form a mixture;

heat treating the mixture at about 30 to about 200° C. to form a dried mixture;

heat treating the dried mixture at about 200 to about 500° C. for about 0.1 to about 5 hours; then

heat treating at 600 to about 900° C. for about 0.1 to about 10 hours to manufacture the particle, wherein the particle comprises a plurality of crystallites comprising a first composition having a layered α-NaFeO 2 -type structure and comprising Li, Ni, Co, and O; and

a grain boundary between adjacent crystallites of the plurality of crystallites and comprising a second composition having a layered α-NaFeO 2 -type structure, a cubic structure, or a combination thereof,

wherein a concentration of cobalt in the grain boundary is greater than a concentration of cobalt in the crystallites.