High power electrode materials
First Claim
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1. A method to form an ammonium iron phosphate for use to make an electrode active material, comprising:
- (a) introducing an iron (II) salt, a phosphate source, an ammonium source, and an oxidizing agent into an aqueous solution to form a mixture;
(b) filtering the mixture to recover a solid by-product;
(c) re-dispersing the solid by-product into an aqueous solution;
(d) heating the aqueous solution;
(e) filtering the solution to recover a solid; and
(f) drying the solid to obtain a high purity spheniscidite with a formula of NH4Fe2(PO4)2OH.2H2O.
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Abstract
An LFP electrode material is provided which has improved impedance, power during cold cranking, rate capacity retention, charge transfer resistance over the current LFP based cathode materials. The electrode material comprises crystalline primary particles and secondary particles, where the primary particle is formed from a plate-shaped single-phase spheniscidite precursor and a lithium source. The LFP includes an LFP phase behavior where the LFP phase behavior includes an extended solid-solution range.
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Citations
40 Claims
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1. A method to form an ammonium iron phosphate for use to make an electrode active material, comprising:
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(a) introducing an iron (II) salt, a phosphate source, an ammonium source, and an oxidizing agent into an aqueous solution to form a mixture; (b) filtering the mixture to recover a solid by-product; (c) re-dispersing the solid by-product into an aqueous solution; (d) heating the aqueous solution; (e) filtering the solution to recover a solid; and (f) drying the solid to obtain a high purity spheniscidite with a formula of NH4Fe2(PO4)2OH.2H2O. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 27)
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16. A method to form crystalline spheniscidite material for use as an electrode active material, comprising:
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(a) introducing an iron (II) salt, a phosphate source, an ammonium source, and an oxidizing agent into an aqueous solution to form a mixture; (b) filtering the mixture to recover a solid by-product; (c) re-dispersing the solid by-product into an aqueous solution; (d) heating the aqueous solution; (e) filtering the solution to recover a solid; and (f) drying the solid to obtain a high purity spheniscidite with a formula of NH4Fe2(PO4)2OH.2H2O, wherein the crystalline spheniscidite material is an ammonium iron phosphate substantially free of impurities; and
wherein the crystalline spheniscidite material has a plate-shape morphology. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24, 25, 26)
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28. A method for synthesizing ammonium iron phosphate for use as an electrode active material in an electrochemical cell, comprising:
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introducing an iron (II) salt, a phosphate source, an ammonium source, and an oxidizing agent into an aqueous solution to form a mixture; filtering the mixture to recover a solid by-product; re-dispersing the solid by-product into an aqueous solution; heating the aqueous solution at a temperature in a range of 85-95°
C.;filtering the solution to recover a solid; drying the solid to obtain a high purity spheniscidite with a formula of NH4Fe2(PO4)2OH.2H2O having a surface area in a range of 20-25 m2/g. - View Dependent Claims (29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40)
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Specification