Method for preparing lithium metal phosphate (LMP) cathode materials
An improved process for forming a lithium metal phosphate cathode material is provided. The process comprises reacting a metal source, a phosphate containing acid such as phosphoric acid, and an organic acid in solvent to form a metal phosphate. A lithium source is added to the solvent and a precipitate is allowed to form. The precipitate is dried and calcined thereby forming lithium iron phosphate cathode material wherein the lithium iron phosphate cathode material comprises up to 3 wt % carbon.
1 . A process for forming a lithium metal phosphate cathode material comprising:
reacting a metal source, phytic acid and an organic acid in solvent to form a metal phosphate;
adding a lithium source to said solvent;
allowing a precipitate to form;
drying said precipitate; and
calcining said precipitate thereby forming said lithium iron phosphate cathode material wherein said lithium iron phosphate cathode material comprises up to 3 wt % carbon.
2 . The process for forming a lithium metal phosphate cathode material of claim 1 wherein said metal source comprises zero valent metal.
3 . The process for forming a lithium metal phosphate cathode material of claim 2 wherein said zero valent metal is selected from the group consisting of Fe, Mn, Ni and Co.
4 . The process for forming a lithium metal phosphate cathode material of claim 1 wherein said metal source comprises elemental iron or an alloy comprising iron.
5 . The process for forming a lithium metal phosphate cathode material of claim 1 wherein said alloy comprising iron is steel.
6 . The process for forming a lithium metal phosphate cathode material of claim 1 wherein said solvent is water.
7 . The process for forming a lithium metal phosphate cathode material of claim 1 wherein said organic acid comprises at least one carboxylic group.
8 . The process for forming a lithium metal phosphate cathode material of claim 1 wherein said organic acid is selected from the group consisting of citric acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioc acid, dodecanedioc acid, citric acid, isocitric acid, aconitic acid, propane-1,2,3-tricarboxylic acid, sucrose and polyvinyl acid.
9 . The process for forming a lithium metal phosphate cathode material of claim 8 wherein said organic acid is selected from the group consisting of oxalic acid and citric acid.
10 . The process for forming a lithium metal phosphate cathode material of claim 1 wherein said lithium iron phosphate cathode material has the formula:
LiFe x Ni a Mn y Co z PO 4 wherein x+a+y+z= 1
wherein:
0≤x≤1;
0<y≤1;
0<z≤1; and
0<a≤0.1.
11 . The process for forming a lithium metal phosphate cathode material of claim 10 wherein said 0.5≤x≤1.
12 . The process for forming a lithium metal phosphate cathode material of claim 11 wherein said 0.9≤x≤1.
13 . The process for forming a lithium metal phosphate cathode material of claim 10 wherein said 0≤y≤0.5.
14 . The process for forming a lithium metal phosphate cathode material of claim 10 wherein said 0≤z≤0.5.
15 . The process for forming a lithium metal phosphate cathode material of claim 1 wherein said carbon is a coating.
16 . The process for forming a lithium metal phosphate cathode material of claim 1 comprising at least 1 wt % carbon.
17 . The process for forming a lithium metal phosphate cathode material of claim 16 comprising no more than 2.5 wt % carbon.
18 . The process for forming a lithium metal phosphate cathode material of claim 17 comprising 1.4 to 1.7 wt % carbon.
19 . The process for forming a lithium metal phosphate cathode material of claim 1 wherein said drying is selected from thin film drying and evaporative drying.
20 . The process for forming a lithium metal phosphate cathode material of claim 19 wherein said evaporative drying comprises spray drying at an inlet temperature of 150° C. to 180° C.
21 . The process for forming a lithium metal phosphate cathode material of claim 19 wherein said thin film drying comprises drying in a drum dryer wherein said drum dryer comprises a heated drum and an alternate heat source external to said drum.
22 . The process for forming a lithium metal phosphate cathode material of claim 21 wherein said alternate heat source is selected from infrared, laser heat and UV heat.
23 . The process for forming a lithium metal phosphate cathode material of claim 1 wherein said calcining is at a temperature of 580° C. to 700° C.
24 . The process for forming a lithium metal phosphate cathode material of claim 1 wherein said calcining comprises rotating said powder during said drying.
25 . The process for forming a lithium metal phosphate cathode material of claim 1 further comprising wet milling of said precipitate prior to said drying.
26 . The process for forming a lithium metal phosphate cathode material of claim 25 wherein said wet milling comprises milling with 1-1.2 mm zirconia beads at a residence time of about 5-10 min/kg at a tip speed of about 10-15 m/s.
27 . A process for forming a lithium metal phosphate cathode material comprising:
reacting a metal source, phytic acid and an organic acid in solvent to form a metal phosphate;
adding a lithium source to said solvent;
allowing a precipitate to form;
drying said precipitate wherein said drying is thin film drying wherein said thin film drying comprises drying in a drum drying wherein said drum drying comprises a heated drum and an alternative heat source external to said drum; and
calcining said precipitate thereby forming said lithium iron phosphate cathode material wherein said lithium iron phosphate cathode material comprises up to 3 wt % carbon.
28 . The process for forming a lithium metal phosphate cathode material of claim 27 wherein said metal source comprises zero valent metal.
29 . The process for forming a lithium metal phosphate cathode material of claim 28 wherein said zero valent metal is selected from the group consisting of Fe, Mn, Ni and Co.
30 . The process for forming a lithium metal phosphate cathode material of claim 27 wherein said metal source comprises elemental iron or an alloy comprising iron.
31 . The process for forming a lithium metal phosphate cathode material of claim 27 wherein said alloy comprising iron is steel.
32 . The process for forming a lithium metal phosphate cathode material of claim 27 wherein said solvent is water.
33 . The process for forming a lithium metal phosphate cathode material of claim 27 wherein said organic acid comprises at least one carboxylic group.
34 . The process for forming a lithium metal phosphate cathode material of claim 27 wherein said organic acid is selected from the group consisting of citric acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioc acid, dodecanedioc acid, citric acid, isocitric acid, aconitic acid, propane-1,2,3-tricarboxylic acid, sucrose and polyvinyl acid.
35 . The process for forming a lithium metal phosphate cathode material of claim 34 wherein said organic acid is selected from the group consisting of oxalic acid and citric acid.
36 . The process for forming a lithium metal phosphate cathode material of claim 27 wherein said lithium iron phosphate cathode material has the formula:
LiFe x Ni a Mn y Co z PO 4 wherein x+a+y+z= 1
wherein:
0≤x≤1;
0<y≤1;
0<z≤1; and
0<a≤0.1.
37 . The process for forming a lithium metal phosphate cathode material of claim 36 wherein said 0.5≤x≤1.
38 . The process for forming a lithium metal phosphate cathode material of claim 37 wherein said 0.9≤x≤1.
39 . The process for forming a lithium metal phosphate cathode material of claim 36 wherein said 0≤y≤0.5.
40 . The process for forming a lithium metal phosphate cathode material of claim 36 wherein said 0≤z≤0.5.
41 . The process for forming a lithium metal phosphate cathode material of claim 27 wherein said carbon is a coating.
42 . The process for forming a lithium metal phosphate cathode material of claim 27 comprising at least 1 wt % carbon.
43 . The process for forming a lithium metal phosphate cathode material of claim 42 comprising no more than 2.5 wt % carbon.
44 . The process for forming a lithium metal phosphate cathode material of claim 43 comprising 1.4 to 1.7 wt % carbon.
45 . The process for forming a lithium metal phosphate cathode material of claim 27 wherein said alternate heat source is selected from infrared, laser heat and UV heat.
46 . The process for forming a lithium metal phosphate cathode material of claim 27 wherein said calcining is at a temperature of 580° C. to 700° C.
47 . The process for forming a lithium metal phosphate cathode material of claim 27 wherein said calcining comprises rotating said powder during said drying.
48 . The process for forming a lithium metal phosphate cathode material of claim 27 further comprising wet milling of said precipitate prior to said drying.
49 . The process for forming a lithium metal phosphate cathode material of claim 48 wherein said wet milling comprises milling with 1-1.2 mm zirconia beads at a residence time of about 5-10 min/kg at a tip speed of about 10-15 m/s.