High voltage lithium ion positive electrode material
A positive electrode material having a nominal stoichiometry Li 1+y/2 Co 1−x−y−z−d Si z Fe x M y M′ d (PO 4 ) 1+y/2 where M is a trivalent cation selected from at least one of Cr, Ti, Al, Mn, Ni, V, Sc, La and/or Ga, M′ is a divalent cation selected from at least one of Mn, Ni, Zn, Sr, Cu, Ca and/or Mg, y is within a range of 0<y≦0.10 and x is within a range of 0≦x≦0.2. The use of double compositional modification to LiCoPO 4 increases the discharge capacity from ˜100 mAh/g to about 130 mAh/g while retaining the discharge capacity retention of the singly Fe-substituted LiCoPO 4 . Additional compositional modification to include Si increases the cycle life and greatly improved the coulombic efficiency to between 97-100% at a C/3 cycle rate.
1. A positive electrode material comprising:
a Li-ion positive electrode material having a nominal stoichiometry of:
Li 1+y/2 Co 1−x−y−z−d Si z Fe x M y M′ d (PO 4 ) 1+y/2
where M is a trivalent cation selected from at least one of Cr, Ti, Al, Mn, Ni, V, Sc, La and/or Ga, M′ is a covalent cation selected from at least one of Mn, Ni, Zn, Sr, Cu, Ca and/or Mg, y is within a range of 0<y≦0.10, x is within a range of 0≦x≦0.20, z is within a range of 0≦z≦0.10 and d is within a range of 0≦d≦0.20;
said Li-ion positive electrode material having an initial capacity of at least 120 mAh/g and a discharge capacity of at least 100 mAh/g after 500 cycles.
2. The positive electrode material of claim 1 , wherein z=0, y is within the range of 0.02≦y≦0.08, x is within the range of 0.05≦x≦0.15 and M=Cr.
3. The positive electrode material of claim 2 , wherein y is within the range of 0.04≦y<0.06 and x is within the range of 0.08≦x≦0.12.
4. The positive electrode material of claim 2 , wherein y=0.05 and x=0.10.
5. The positive electrode material of claim 4 , wherein said Li-ion positive electrode material has an initial capacity of at least 125 mAh/g and a discharge capacity of at least 105 mAh/g after 500 cycles.
6. The positive electrode material of claim 1 , wherein z=0, y is within the range of 0.02≦y≦0.08, x is within the range of 0.05≦x≦0.15 and M=Ti.
7. The positive electrode material of claim 1 , z is within a range of 0<z≦0.1.
8. The positive electrode material of claim 7 , wherein said Li-ion positive electrode material has a coulombic efficiency between 97-100% at a C/3 cycle rate.
9. The positive electrode material of claim 7 , wherein z is within the range of 0<z≦0.05.
10. The positive electrode material of claim 9 , wherein z is within the range of 0<z≦0.02.
11. The positive electrode material of claim 10 , wherein z=0.01.
12. A high voltage lithium ion positive electrode material comprising:
a Li-ion positive electrode material having a nominal stoichiometry of:
Li 1+y/2 Co 1−x−y−z−d Si z Fe x M y M′ d (PO 4 ) 1+y/2
where M is a trivalent cation selected from at least one of Cr, Ti, Al, Mn, Ni, V, Sc, La and/or Ga, M′ is a divalent cation selected from at least one of Mn, Ni, Zn, Sr, Cu, Ca and/or Mg, y is within a range of 0<y≦0.10, x is within a range of 0≦x≦0.20, z is within a range of 0≦z≦0.10 and d is within a range of 0≦d≦0.20;
said Li-ion positive electrode material having a discharge capacity of at least 100 mAhg −1 after 500 cycles.
13. The positive electrode material of claim 12 , wherein z=0, y is within the range of 0.02≦y≦0.08, x is within the range of 0.05≦x≦0.15 and M=Cr.
14. The positive electrode material of claim 13 , wherein y is within the range of 0.04≦y≦0.06 and x is within the range of 0.08≦x≦0.12.
15. The positive electrode material of claim 13 , wherein y=0.05 and x=0.10.
16. The positive electrode material of claim 15 , wherein said Li-ion positive electrode material has an initial capacity of at least 125 mAh/g and a discharge capacity of at least 105 mAh/g after 500 cycles.
17. The positive electrode material of claim 12 , wherein z=0, y is within the range of 0.02≦y≦0.08, x is within the range of 0.05≦x≦0.15 and M=Ti.
18. The positive electrode material of claim 12 , wherein z is within a range of 0<z≦0.10.
19. The positive electrode material of claim 18 , wherein z is within the range of 0<z≦0.05.
20. The positive electrode material of claim 19 , wherein z=0.01.
21. The positive electrode material of claim 6 , wherein y is within the range of 0.04≦y≦0.06 and x is within the range of 0.08≦x≦0.12.
22. The positive electrode material of claim 6 , wherein y=0.05 and x=0.10.
23. The positive electrode material of claim 17 , wherein y is within the range of 0.04≦y≦0.06 and x is within the range of 0.08≦x≦0.12.
24. The positive electrode material of claim 17 , wherein y=0.05 and x=0.10.
25. The positive electrode material of claim 18 , wherein said Li-ion positive electrode material having a coulombic efficiency between 97-100% at a C/3 cycle rate.
26. The positive electrode material of claim 1 , wherein d=0.
27. The positive electrode material of claim 12 , wherein d=0.