High power electrode materials

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.

1 . A method to synthesize lithium iron phosphate, comprising:
 forming a mixture by mixing spheniscidite, a lithium source, a dopant, a carbon source, and a solvent to form a slurry, wherein the spheniscidite is derived from an iron source, an ammonium source, and an oxidant;   milling the mixture;   drying the milled mixture; and   firing the dried mixture to obtain lithium iron phosphate.   
     
     
         2 . The method of  claim 1 , wherein the firing the mixture includes firing the mixture in an inert atmosphere. 
     
     
         3 . The method of  claim 1 , wherein the spheniscidite is plate-shaped. 
     
     
         4 . The method of  claim 1 , wherein the solvent is an alcohol or water. 
     
     
         5 . The method of  claim 1 , wherein the lithium source is one or more of Li 2 CO 3 , Li 2 O, LiOH, LiF, and Lil. 
     
     
         6 . The method of  claim 1 , wherein the dopant is one or more of V, Nb, Ti, Al, Mn, Co, Ni, Mg, and Zr. 
     
     
         7 . The method of  claim 1 , wherein the dopant comprises up to 10 molar % the lithium iron phosphate. 
     
     
         8 . The method of  claim 1 , further comprising formulating the obtained lithium iron phosphate into an electrode using conductive additive and a polymeric binder. 
     
     
         9 . A method to synthesize a cathode active material, comprising:
 synthesizing spheniscidite from an ammonium source, iron source, and an oxidant;   forming a mixture by mixing synthesized spheniscidite, a lithium source, a dopant, a carbon source, and a solvent to form a slurry, wherein the synthesized spheniscidite is plate-shaped;   milling the mixture;   drying the milled mixture; and   chemically reducing the dried mixture via a temperature programmed reaction under nitrogen to obtain the cathode active material.   
     
     
         10 . The method of  claim 9 , wherein the carbon source is one or more of PVB, citric acid, sugar, PVA, or glycerol. 
     
     
         11 . The method of  claim 9 , wherein the obtained cathode active material is LiFePO 4 . 
     
     
         12 . The method of  claim 9 , wherein the obtained cathode active material has a spherical secondary particle shape when the solvent is water. 
     
     
         13 . The method of  claim 9 , wherein the obtained cathode active material has a primary particle size between 20 nm and 80 nm when the solvent is one of water or alcohol. 
     
     
         14 . The method of  claim 9 , wherein the obtained cathode active material includes less than 5 weight percent of a phase that does not store ions. 
     
     
         15 . A method to synthesize a material for an electrode material, comprising:
 selecting a solvent from one of water or alcohol;   forming a mixture by mixing spheniscidite, a lithium source, and the selected solvent to form a slurry;   milling the mixture;   drying the milled mixture; and   firing the dried mixture to obtain the electrode material composed of primary and secondary particles, wherein a shape of the secondary particles is based the selection of solvent.   
     
     
         16 . The method of  claim 15 , wherein the shape of the secondary particles is spherical when water is selected. 
     
     
         17 . The method of  claim 16 , wherein the secondary particles have a d50 particle size in a range of 5 microns to 13 microns. 
     
     
         18 . The method of  claim 16 , wherein the secondary particles have tap density in a range of 0.8 g/mL to 1.4 g/mL. 
     
     
         19 . The method of  claim 15 , wherein forming the mixture further includes mixing a dopant and a carbon source with the spheniscidite, the lithium source, and the solvent. 
     
     
         20 . The method of  claim 15 , wherein the spheniscidite comprises from about 25 wt. % to about 30 wt. % iron, 15 wt. % to about 20 wt. % phosphorous, from about 4.6 wt. % to about 5.0 wt. % ammonium, and wherein a molar ratio of phosphorous to iron is from about 1 to about 1.25.