High power electrode materials

Patent metadata

Field	Value
Publication number	US-2016380269-A1
Application number	US-201615221228-A
Country	US
Kind code	A1
Filing date	Jul 27, 2016
Priority date	Sep 18, 2009
Publication date	Dec 29, 2016
Grant date	—

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.

First claim

1 - 5 . (canceled)

6 . 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.

7 . The method of claim 6 , wherein the high purity spheniscidite is a single-phase.

8 . The method of claim 6 , wherein the high purity spheniscidite has a plate-shape morphology.

9 . The method of claim 6 , wherein the iron (II) salt is selected from iron (II) sulfate, iron (II) chloride, iron (II) nitrate, any hydrate thereof, or a mixture thereof

10 . The method of claim 6 , wherein the phosphate source is selected from H3PO4, P2O5, NH4H2PO4, (NH4)2HPO4, (NH4)3PO4, NaH2PO4, Na2HPO4, Na3PO4, or mixtures thereof.

11 . The method of claim 6 , wherein the ammonium source is selected from NH4H2PO4, (NH4)2HPO4, (NH4)3PO4, NH4OH or mixtures thereof.

12 . The method of claim 6 , wherein the oxidizing agent is selected from H2O2, Na2O, NaClO3, or mixtures thereof.

13 . The method of claim 6 , further comprising rinsing the solid by-product and/or solid following filtering.

14 . The method of claim 6 , further comprising:
(g) mixing the obtained high purity spheniscidite, a lithium source, a dopant, and a carbon source; (h) adding a solvent to produce a slurry; (i) milling the slurry; (j) drying the milled slurry; and (k) firing the dried milled slurry to obtain the lithium iron phosphate, wherein the lithium iron phosphate comprises a substantially olivine crystalline phase, a primary particle in the range of 20 nm to 80 nm, a secondary particle with d50 in the range of 5 μm to 13 μm, and a surface area of 25 m2/g to 35 m2/g, a carbon percentage of about 2.3%; and wherein the lithium iron phosphate improves battery performance at low temperatures in comparison to current lithium iron phosphate materials.

15 . The method of claim 14 , wherein the slurry is milled to obtain primary particles of about 20 nm to about 80 nm.

16 . The method of claim 14 , wherein the solvent is water.

17 . The method of claim 14 , wherein the solvent is a compound comprising an alcohol functional group.

18 . The method of claim 14 , wherein the low temperatures are at 0° C. or lower.

19 . An electrode material for use in a battery comprising:
crystalline primary particles and secondary particles, where the primary particle is formed from a plate-shaped single-phase ammonium iron phosphate spheniscidite precursor and a lithium source; where the crystalline primary particles and secondary particles exhibit an LFP phase behavior including an extended solid-solution range; and wherein the electrode material improves the capacity of a battery at low temperatures in comparison to current lithium iron phosphate materials.

20 . The electrode material of claim 19 , wherein the extended solid solution range is a wider range of lithium composition over which a solid solution occurs in comparison to the solid solution range for an electrode material not derived from the spheniscidite precursor but having similar particle size or exhibiting similar x-ray peak broadening.

21 . The electrode material of claim 19 , wherein the extended solid solution range has a composition LixFePO4, where x exceeds 0.2 at Li-poor compositions and is less than 0.8 at Li-rich compositions, at about 45° C.; and
wherein the primary particles have a particle size in the range of 20 nm to 80 nm.

22 . The electrode material of claim 19 , wherein the primary particles have a particle size in the range of 20 nm to 80 nm.

23 . The electrode material of claim 19 , wherein the secondary particles have a surface area of 25 m2/g to 35 m2/g.

24 . The electrode material of claim 19 , wherein the primary particles have a tap density from about 0.8 g/mL to 1.4 g/mL.

25 . The electrode material of claim 19 , wherein the secondary particles have a d50 particle size of about 10 microns.

26 . The electrode material of claim 19 , wherein the electrode material has a carbon percentage of about 2.1% to 2.5%.

27 . The electrode material of claim 19 , wherein the lithium source comprises Li2CO3.

28 . The electrode material of claim 19 , wherein the plate-shaped single-phase ammonium iron phosphate precursor has a surface area in a range of 20 m2/g to 25 m2/g.

29 . The electrode material of claim 19 , wherein the secondary particles are formed from a water-based process and are substantially spherical shaped.

30 . The electrode material of claim 19 , wherein the secondary particles are formed from a solvent based process.

31 . The electrode material of claim 19 , wherein the rate-capability at 10 C is greater than 130 mAh/g in a Swagelok half-cell.

32 . The electrode material of claim 19 , wherein a direct current resistance pulse discharge at −20° C. has at least a 10% increase as compared to a control electrode material not formed from the plate-shaped single-phase spheniscidite precursor wherein electrochemical cell components are the same.

33 . The electrode material of claim 19 , wherein first charge capacity and first discharge capacity are lower than a control electrode material not formed from the plate-shaped single-phase spheniscidite precursor wherein electrochemical cell components are the same.

34 . The electrode material of claim 19 , wherein alternating current resistance impedance is lower than a control electrode material not formed from the plate-shaped single-phase spheniscidite precursor wherein electrochemical cell components are the same.

35 . The electrode material of claim 19 , wherein direct current resistance at 1 s and 20 s pulse power at −20° C. and at 10 s pulse power at −30° C. is lower than a control electrode material not formed from the plate-shaped single-phase spheniscidite precursor wherein electrochemical cell components are the same.

36 . The electrode material of claim 19 , wherein power during cold cranking at −30° C. is greater than a control electrode material not formed from the plate-shaped single-phase spheniscidite precursor wherein electrochemical cell components are the same.

37 . An electrochemical cell comprising:
a negative electrode capable of intercalating and liberating lithium; a positive electrode comprising an electrode material comprising crystalline primary particles and secondary particles, where the primary particle is formed from a plate-shaped single-phase spheniscidite precursor and a lithium source; a nonaqueous electrolyte solution; a separator; a container housing the said negative electrode, positive electrode, nonaqueous electrolyte solution, and separator; and wherein the positive electrode material improves the capacity of the electrochemical cell at low temperatures and has a phase behavior wherein the phase behavior includes an extended solid solution range at each of low and high states of charge where the range is at least 10% at an av

Assignees

• A123 Systems Llc

Inventors

• Beck Larry
• Wilson Jennifer
• Xu Chuanjing
• Shi Zhong-You
• Hammoud Maha

Classifications

• C01P2006/11

  Powder tap density · CPC title

• C01P2002/74

  by peak-intensities or a ratio thereof only · CPC title

• C01P2004/32

  Spheres · CPC title

• C01B25/45

  containing plural metal, or metal and ammonium · CPC title

• C01P2006/12

  Surface area · CPC title