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1. (WO2019043403) PROCESS FOR PRODUCING PARTICULATE CARBON-COATED LITHIUM IRON PHOSPHATE, CARBON COATED LITHIUM IRON PHOSPHATE AND ITS USES
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Claims

1. Process for producing particulate carbon-coated lithium iron phosphate, the process comprising:

- a milling step in which lithium-containing precursor, dehydrated iron phosphate and carbon-containing precursor are combined and subjected to milling; and

a calcination step in which the product of the milling step is calcined to provide carbon coated particulate lithium iron phosphate,

wherein the carbon-containing precursor is polyvinyl butyral having a molecular weight distribution such that at least 75% of the polyvinyl butyral has a molecular weight in the range from 30000 to 90000.

2. Process according to claim 1 wherein the polyvinyl butyral has a butyryl content of at least 70 wt%, and optionally 86 wt% or less.

3. Process according to any one of the preceding claims wherein the polyvinyl butyral has a hydroxyl content of 30 wt% or less, and optionally 14 wt% or more

4. Process according to any one of the preceding claims wherein the polyvinyl butyral has a viscosity in the range from 50 to 350 cP when measured as a 10 wt% solution in isopropyl alcohol at a shear rate of 100 1/s.

5. Process according to any one of the preceding claims wherein the lithium-containing precursor is lithium carbonate.

6. Process according to any one of the preceding claims wherein the milling step is a wet high energy milling step.

7. Process according to claim 6 wherein the milling step is carried out in isopropyl alcohol.

8. Process according to any one of the preceding claims, in which the lithium iron phosphate has the formula LixFeyP04, in which x is 0.8-1.2 and y is 0.8-1.2, and in which up to 10 atom % of the Fe may be replaced with a dopant metal, up to 10 atom % of the phosphate may be replaced with S04 and/or Si04 and up to 10 atom % of the Li may be replaced with Na and/or K.

9. Process according to any one of the preceding claims, further comprising forming an electrode comprising the carbon-coated lithium iron phosphate.

10. Process according to claim 9, further comprising constructing a battery including the electrode.

1 1. Particulate carbon-coated lithium iron phosphate obtained or obtainable by a process according to any one of claims 1 to 10.

12. Use of particulate carbon-coated lithium iron phosphate according to claim 11 in the preparation of an electrode for a secondary lithium ion battery.

13. An electrode for a secondary lithium ion battery comprising particulate carbon-coated lithium iron phosphate according to claim 11.

14. A secondary lithium ion battery comprising an electrode according to claim 13.