LMFP Cathode Materials with Improved Electrochemical Performance
AssigneeDow Global Technologies LLC
InventorsShrikant N. KHOT, Deidre A. Strand, Jamie L. Cohen, Thierry Drezen, Steven S. Kaye, Bin Li
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Abstract
Particulate LMFP cathode materials having high manganese contents and small amounts of dopant metals are disclosed. These cathode materials are made by milling a mixture of precursor materials in a wet or dry milling process. Preferably, off-stoichiometric amounts of starting materials are used to make the cathode materials. Unlike other high manganese LMFP materials, these cathode materials provide high specific capacities, very good cycle life and high energies even at high discharge rates.
Claims18
A particulate cathode material comprising an electroactive material having the empirical formula LiaMnbFecDdPO4, wherein
- a is a number from 0.95 to 1.10;
- b is from 0.70 to 0.95;
- c is from 0.049 to 0.349;
- d is from 0.005 to 0.10;
- (a+2b+2c+dV) is 2.85 to 2.99 or 3.01 to 3.05, wherein V is the valence of D, and D is a metal ion selected from one or more of magnesium, calcium, strontium, cobalt, titanium, zirconium, molybdenum, vanadium, niobium, nickel, scandium, chromium, copper, zinc, beryllium, lanthanum and aluminum, and further wherein at least a portion of the electroactive material has an olivine structure.
3-4. (canceled)
A method for making an olivine lithium manganese transition metal phosphate cathode material, comprising
- a) forming a mixture of at least one lithium precursor, at least one iron precursor, at least one manganese precursor, at least one dopant metal precursor and at least one precursor of HxPO4 ions where x is 0, 1 or 2, wherein the precursors are present in amounts such that:
- the mole ratio of lithium ions to HxPO4 ions is 0.95 to 1.1;
- the mole ratio of manganese ions to HxPO4 ions is 0.70 to 0.95;
- the mole ratio of iron ions to HxPO4 ions is 0.049 to 0.349;
- the mole ratio of dopant metal ions to HxPO4 ions is 0.005 to 0.10;
- and
- the mole ratio of lithium, manganese, iron and dopant metal ions combined to HxPO4 ions is such that [moles Li+(2×moles Mn)+(2×moles Fe)+(2×moles Dopant Metal)] is (2.85 to 2.99×Moles HxPO4) or (3.01 to 3.05×Moles HxPO4);
- b) milling the mixture and then;
- c) calcining the milled mixture to form the olivine lithium manganese iron phosphate cathode material.
13-14. (canceled)
Dependencies are inferred from the claim text.