Process for conversion of stoichiometrically imbalanced materials into useful cathode materials

Abstract

The present invention relates to olivine-type cathode materials useful in lithium-ion batteries. More specifically, the present invention includes methods for stoichiometrically balancing olivine-type lithium-transition metal-phosphate materials synthesized using one of the various synthesis routes known in the art.

Description

PROCESS FOR CONVERSION OF STOICHIOMETRICALLY IMBALANCED MATERIALSINTO USEFUL CATHODE MATERIALSCROSS-REFERENCE

[0001] The present patent application claims the benefit of priority to a Provisional Patent Application Serial No. 63 / 561,677, entitled “Process for Conversion of Stoichiometrically Imbalanced Materials into Useful Cathode Materials,” filed on March 05, 2024, which is incorporated herein by reference in its entirety.TECHNICAL FIELD

[0002] The present invention relates to synthesis of olivine-type cathode materials useful in lithium-ion batteries. More specifically, the present invention relates to manufacturing stoichiometrically balanced olivine-type cathode materials.BACKGROUND

[0003] Lithium-ion batteries are the most promising portable energy source in electronic devices, including electric vehicles and hybrid electric vehicles, because of their high working voltage, high energy density, and good cyclic performance. In these batteries, olivine-type cathode materials such as LiMPO4 (M=Fe and Mn) have attracted significant interest, as LiMPO4 has low cost and high intrinsic safety. The olivine-type cathode materials can be synthesized by various methods including, but and not limited to, fusion synthesis, hydrothermal synthesis, solid state synthesis, melt synthesis, and similar methods. The known synthesis methods typically utilize a near-l:l:l stoichiometric balance of lithium, transition metal, and phosphate ions in the chemical formula for producing a highly pure cathode material with negligible impurities. However, for either intentional or unintentional reasons, the 1:1:1 balance between the lithium, transition metal, and the phosphate ions may be disturbed. When disturbed the resultant product does not perform as desired. But it is desirable to retain the investment made in creating these faulty intermediate compositions without having to return them to purified starting materials.

[0004] As noted above, olivine-type cathode materials synthesized by the methods available in the art are inefficient, for example, these methods tend to produce cathode materials with oxidized impurities which require further processing. In addition, there is an undesirablestoichiometric imbalance between the lithium, transition metal and phosphate ions in the materials produced by using the synthesis methods available in the art.BRIEF SUMMARY

[0005] Provided herein, inter alia, is a method for producing stoichiometrically balanced olivine-type lithium-transition metal-phosphate (LMP) materials which allows stoichiometrically imbalanced olivine starting materials to be used instead of being discarded.

[0006] In a first aspect, the method includes dry milling particles of a non-stoichiometric olivine-type LMP material to obtain a dry milled LMP powder. It further includes, adding an ion source to the dry milled LMP powder to form a mixture. The ion source includes one or more of lithium ions, transition metal ions, and phosphate ions. The method further includes milling the LMP powder and ion source mixture with a liquid medium to form a wet -milled slurry. Additionally, the method includes drying the wet-milled slurry to yield primary particles including particles of the olivine-type LMP material, and the ion source. The primary particles have a d50 ranging from about 50 nm to about 5000 nm. Further, the method includes calcining the primary particles to produce secondary particles comprising LMP having a d50 ranging from about 50 nm to about 5000 nm. The ratio of LMP in the secondary particles is stoichiometrically balanced for the lithium (L), transition metal (M), and phosphate (P).

[0007] In an aspect, the non-stoichiometric olivine-type LMP material is a compound having the formula: Lixi(M)X2(PO4)X3; wherein: M is one or more of Fe and Mn; and wherein one or more of xl, x2, and x3 are less than or equal to 0.98.

[0008] In another aspect, the stoichiometrically balanced LMP in the secondary particles is a compound having the formula, Lixi(M)X2(PO4)X3, wherein M is one or more of Fe and Mn and wherein 0.98<xl<1.02; 0.98 < x2 < 1.02; and 0.98 < x3 < 1.02.

[0009] In another aspect, the stoichiometrically balanced LMP in the secondary particles is a compound having the formula, Lixi(M)X2Ay(PC>4)X3, wherein M is one or more of Fe and Mn and wherein 0.98<xl<1.02; 0.98 < x2 < 1.02; 0.98 < x3 < 1.02 and y is 0.0 to 0.1.

[0010] In an embodiment, the step of adding an ion source to the dry milled LMP powder to form a mixture further includes adding a dopant (A). The dopant is selected from one or more of Mg, Sc, Ti, V, Cr, Co, Ni, Zn, Mo, Nb, W, Al, Si, and Sn.

[0011] In another embodiment, the method further includes adding an additional compound comprising a carbon-containing compound to the mixture. The carbon-containing compound is selected from the group consisting of glucose, sucrose, lactose, maltodextrin, soluble starch, polyethylene glycol, vinyl alcohol, acrylic acid, citric acid, oxalic acid, lauric acid, urea, and combinations thereof.

[0012] In another embodiment, the method further includes formulating a cathode sheet using the secondary particles; wherein the secondary particles have a d50 ranging from about 100 nm to about 1000 nm.

[0013] In an embodiment, the dry milled LMP powder has a d50 of less than or equal to 10 pm. In another embodiment, the dry milled LMP powder has a d50 ranging from about 400 nm to about 800 nm. In an embodiment, the secondary particles have a d50 ranging from about 100 nm to about 300 nm.

[0014] In an embodiment, the liquid medium including an organic solvent selected from methanol, ethanol, isopropanol, 2 -butanol, acetone, 2-butanone, and combinations thereof. In another embodiment, the liquid medium is water.

[0015] In an embodiment, the wet-milled slurry is dried by a process of spray drying, air drying, or vacuum drying. In another embodiment, the wet-milled slurry is spray dried with an inlet temperature of about 160 °C and an outlet temperature of about 105 °C. In an embodiment, the calcining occurs for about 1 hour.

[0016] In an aspect of the invention, the ion source includes one or more of Fe(ox)«2H2O, iron oxalate hydrate, Fe(Oac)2, and iron acetate. In another aspect of the invention, the ion source includes one or more of Mn(Oac)2*4H2O, manganese oxalate hydrate; Mn(ox)*2H2O, manganese oxalate hydrate; and MnCCh. In another aspect of the invention, the ion source comprises one or more of H3PO4, (NH4)2HPO4, and (NFL^FhPC

[0017] In an embodiment, calcining is performed using a controlled-atmosphere furnace, wherein traces of oxygen or byproducts are removed through a flow of inert gas in the furnace.

[0018] In another aspect the method includes dry milling particles of a non-stoichiometric olivine-type LMP material to obtain a dry milled LMP powder. It further includes, adding an ion source to the dry milled LMP powder to form a mixture. The ion source includes one or more of lithium ions, transition metal ions, and phosphate ions. The method further includes milling the LMP powder and ion source mixture with a liquid medium to form a wet -milled slurry. Additionally, the method includes spray drying the wet-milled slurry to yield primaryparticles including particles of the olivine-type LMP material, and the ion source. The primary particles have a d50 ranging from about 50 nm to about 5000 nm. The spray drying inlet temperature is about 160 °C and the spray drying outlet temperature is about 105 °C. Further, the method includes calcining the primary particles at a temperature of about 650° C about 800° C to produce secondary particles comprising LMP having a d50 ranging from about 50 nm to about 5000 nm. The ratio of LMP in the secondary particles is stoichiometrically balanced for the lithium (L), transition metal (M), and phosphate (P).BRIEF DESCRIPTION OF FIGURES

[0019] FIG. 1 demonstrates that the expected and observed ratios of Li:P and TM:P align closely, demonstrating that transition metal and lithium added using the methods disclosed herein integrates into the heat treated product;

[0020] FIG. 2A shows the observed stoichiometries of the original fused sample and the seven heat treated samples, labeled A-G. Panel;

[0021] FIG. 2B shows the X-ray diffractogram (XRD) for all seven heat treated samples, demonstrating that all are predominantly, if not entirely, composed of LMFP (Traces are offset vertically for clarity);

[0022] FIG. 2C is an inset highlighting three classes of impurities: Li3PO4 (23.2° and 24.8°), Fe2P (26.5°), and transition metal pyrophosphates (29.1° and 30.4°) ;

[0023] FIG. 3 A shows the XRD diffractograms of the fused sample and heat treated product. (Traces are offset vertically for clarity);

[0024] FIG. 3B is an inset highlighting three classes of impurities: Li3PO4 (23.2° and 24.8°), FeiP (26.5°), and transition metal pyrophosphates (29.1° and 30.4°) ;

[0025] FIG. 4 demonstrates the specific capacity of cells manufactured by using the cathode as described herein; these cells indicated discharge capacities of 156 mAh / g at C / 25 and 143 mAh / g at 1C rates;

[0026] FIG. 5 demonstrates the specific capacity of cells manufactured by using the cathode as described herein; these cells indicated discharge capacities of 148 mAh / g at C / 25 and 132 mAh / g at 1C rates;

[0027] FIG. 6 demonstrates the specific capacity of cells manufactured by using the cathode as described herein; these cells indicated discharge capacities of 156 mAh / g at C / 25 and 138 mAh / g at 1C rates;

[0028] FIG. 7 demonstrates the specific capacity of cells manufactured by using the cathode as described herein; these cells indicated discharge capacities of 152 mAh / g at C / 25 and 136 mAh / g at 1C rates;

[0029] FIG. 8 demonstrates the specific capacity of cells manufactured by using the cathode as described herein; these cells indicated discharge capacities of 156 mAh / g at C / 25 and 138 mAh / g at 1C rates;

[0030] FIG. 9 demonstrates that the specified admixture of samples A, B, and C yields a calculated Li:TM:P ratio of 0.981:0.965: 1.000 in the final product;

[0031] FIG. 10A shows the XRD diffractograms of samples A, B, and C after reductive calcination, as well as the product derived from the admixture. (Traces are offset vertically for clarity); and

[0032] FIG. 10B is an inset highlighting three classes of impurities: Li3PO4 (23.2° and 24.8°), FeiP (26.5°), and transition metal pyrophosphates (29.1° and 30.4°).DETAILED DESCRIPTION

[0033] The present invention includes methods of synthesizing cathode materials comprising stoichiometrically balanced olivine-type lithium-transition metal-phosphate (LMP) material. The cathode material as provided herein is generated from a starting olivine-type lithium- transition metal-phosphate (LMP) material that has an incorrect and / or undesirable stoichiometric balance of lithium, transition metal, and phosphate ions. The balanced LMP material, as produced with the methods described herein is substantially pure with little or no oxidized impurities. Further, the resultant LMP exhibits improved discharge capacities.

[0034] In particular, the instant invention includes a method for producing stoichiometrically balanced olivine-type lithium-transition metal-phosphate (LMP) material from a starting LMP material that is not stoichiometrically balanced. The method includes a number of steps. Firstly, particles of a non-stoichiometric olivine-type LMP material undergo dry milling to obtain a dry milled LMP powder. The dry milled LMP powder is further mixed with an ion source to produce an intimate mixture. The ion source can include one or more of lithium ions, transitionmetal ions, or phosphate ions. Further, the intimate mixture comprising the LMP powder and the ion source is milled with a liquid medium to form a wet-milled slurry. Next, this wet-milled slurry is dried further to yield primary particles comprising particles of the olivine-type LMP material, and the ion source. These primary particles have a d50 ranging from about 50 nm to about 5000 nm. Additionally, these primary particles undergo calcination to produce secondary particles comprising LMP having a d50 ranging from about 50 nm to about 5000 nm. The LMP ratio in the secondary particles as produced herein, is stoichiometrically balanced for the lithium (L), transition metal (M), and phosphate (P).

[0035] As noted above, the starting olivine-type LMP material utilized herein may be non- stoichiometrically balanced, and may include LMP materials having a formula, Lixi(M)x2(PO4)x3. In the formula, M can be one or more of Fe and Mn and the one or more of xl, x2 and x3 are less than or equal to about 0.98, about 0.97, about 0.96, about 0.95, about 0.94, about 0.93. about 0.92, about 0.91, about 0.90, about 0.89, about 0.88, about 0.87, about 0.86, about 0.85, about 0.84, about 0.83, about 0.82, about 0.81, or about 0.80. In some embodiments xl is in the range of about 0.8 to about 0.98, and x2 and x3 are in the range of about 0.98 to about 1.02. Alternatively, in some other embodiments x2 is in the range of about 0.8 to about 0.98, and xl and x3 are in the range of about 0.98 to about 1.02. In yet another embodiment x3 is in the range of about 0.8 to about 0.98, and x2 and x3 are in the range of about 0.98 to about 1.02.

[0036] The transition metal (M) of the LMP compound may include one or more of iron (Fe) and / or manganese (Mn). In a particular aspect, both Fe and Mn can be selected as the transition metal (M), then the x2 value represents the cumulative molar amount of the two ions, and the relative ratio of Fe to Mn ions for the M component of LMP may range from about 0.05:about 0.95 to about 0.95:about 0.05, including specific Fe:Mn ratios of about O.kabout 0.9, about 0.15:about 0.85, about 0.2:about 0.8, about 0.25:about 0.75, about 0.3:about 0.7, about 0.35:about 0.65, about 0.4:about 0.6, about 0.45:about 0.55, about 0.5:about 0.5, about 0.55:about 0.45, about 0.6:about 0.4, about 0.65:about 0.35, about 0.7:about 0.3, about 0.75:about 0.25, about 0.8:about 0.2, about 0.85:about 0.15, about 0.9:about 0.1, and about 0.95:about 0.05.

[0037] In one particular embodiment, the starting LMP material including the non- stoichiometric olivine-type LMP material may be a compound having the formula:Lixi(M)x2(PO4)x3; wherein: M= one or more of Fe and Mn; and wherein one or more of xl, x2, and x3 are less than or equal to 0.98.

[0038] Alternatively, the LMP material may also have a formula: LixFeyAzPO4. In the formula, y ranges from about 0.8 to about 1.0; about 0.8 to about 0.9; about 0.9 to about 0.98; about 0.8 to about 1.0; about 0.95 to about 1.0; about 0.91 to about 1.0; about 0.92 to about 1.0; about 0.94 to about 1.0; or about 0.96 to about 1.0; wherein z is the range of about 0.01 to about 0.1, about 0.01 to about 0.09, about 0.02 to about 0.08, about 0.03 to about 0.07, about 0.0 to about 0.09, about 0.02 to about 0.09, about 0.02 to about 0.07, about 0.02 to about 0.06, about 0.02 to about 0.05, about 0.0 to about 0.1, about 0.0 to about 0.09, about 0.0 to about 0.08, about 0.0 to about 0.07, about 0.0 to about 0.06 or about 0.0 to about 0.03.

[0039] Further, in the formula LixFeyAzPO4: A can be one or more of alkaline-earth metals or combination thereof. Alternatively, A can be one or more of transition metals or a combination thereof. Optionally, A can be a combination of one or more of alkaline-earth metals and one or more transition metals. Specifically, A can be one or more of the alkaline-earth metal including Be, Mg, Ca, Sr, Ba, or Ra; or A can be one or more of the transition metals including Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Zr, Nb, Mo, Tc, Ru, Rh, Pd, or Cd. More specifically, A can be one or more of: Ti or Mg.

[0040] In one of the embodiments, the LMP material comprises LixFeyAzPO4 wherein x is 0.99-1.02, y is 0.96-1.0, z is 0.00-0.03, and A is one or more of: Ti, or Mg.

[0041] The method as described herein further includes adding one or more ions to the non- stoichiometrically balanced olivine-type LMP starting material, wherein the ions are added to stoichiometrically balance the olivine-type LMP starting material. The dry milled LMP powder forms a mixture with the added ions. In an embodiment, the ion source comprises one or more one or more metals including lithium ions or transition metal ions. The ion source can also include non-metal phosphates.

[0042] For example, the lithium ion source comprises of LiiCCh (lithium carbonate) Li(OAc)«xH2O(lithium acetate dihydrate), and LiOH (lithium hydroxide). In an embodiment, the transition metal ion source comprises Fe(ox)*2H2O (iron oxalate dihydrate), Fe(Oac)2(iron acetate). The transition metal ion source includes Mn(Oac)2*4H2O (manganese(II)acetate tetrahydrate), Mn(ox)*2H2O, manganese oxalate dihydrate; and MnCCh (manganese(II)carbonate) and the phosphate ion source comprises one or more of H3PO4(phosphoric acid), (NFLj^HPC (diammonium hydrogen phosphate), and (NH4)H2PO4 (ammonium dihydrogen phosphate, also known as monoammonium phosphate (MAP).

[0043] In an embodiment, the ion source is added in an amount equal to about 0.0 wt% to about 20 wt%, based on the total weight of the olivine-type LMP material. The ion source may be added in an amount of 0.5 wt% to 15 wt%, 1.5 wt% to 15 wt%, 2.5 wt% to 15 wt%, 3 wt% to 15 wt%. Further the ion source can be added in an amount of 2.5 wt% to 20 wt%, 2.5 wt% to 15 wt%, 2.5 wt% to 10 wt%, 3 wt% to 15 wt%, 3 wt% to 12 wt%, or 3 wt% to 11 wt%.

[0044] In an embodiment, at the least three ions including lithium, transition metal and / or phosphate ions are added from one or more ion sources. The at least three ions may be present in a ratio of 1 :1 :1, 1 :1 :2, 1 :2:1, 2:1:1, 2:2:1, 1 :2:2, 2:1 :2, 1 :1 :3, 1 :3:1, 3:1:1, 3:3:1, 1 :3:3, 3: 1:3; 1 :1 :4, 1:4: 1, 4:1 :1, 4:4: 1, 4:1 :1, 1 :4:4, or 4:1 :4. The at least three ions can also be present in a ratio of 1 :2:3, 1 :3:2, 3:2:1, 2:3: 1, 3:1 :2, 1 :4:3, 3:4:1, 3:1 :4, 1 :3:4, or 4:3: 1. In another embodiment, at least two ions may be added from one or more ion sources, wherein the at least two ions are present in a ratio of 1 : 1, 1 :2, or 2: 1.

[0045] In one aspect, adding an ion source may include adding a dopant (A), wherein the dopant is selected from one or more of Mg, Sc, Ti, V, Cr, Co, Ni, Zn, Mo, Nb, W, Al, Si, and Sn. Further, the dopant (A) may be added in an amount of 0.00 wt% to 0.2 wt%, 0.01 wt% to 0.02 wt%, 0.02 wt% to 0.03 wt%, 0.02 wt% to 0.04 wt%, 0.03 wt% to 0.04 wt%, 0.04 wt% to 0.2 wt%, 0.05 wt% to 0.2 wt%, 0.05 wt% to 0.1 wt%, 0.08 wt% to 0.15 wt%, or 0.1 wt% to 0.2 wt%.

[0046] Further as per the methods described herein the non-stoichiometrically balanced olivine-type LMP material undergoes dry milling to obtain the dry milled LMP powder. The use of dry milling treatment is well known in the art.

[0047] Dry milling causes intensive mixing and, at the same time, deagglomeration or a reduction in the size of the particles. It further results in the reduction of the d50 value of the LMP powder, wherein the dry milled LMP powder has a d50 of less than or equal to 30 pm, less than or equal to 25 pm, less than or equal to 20 pm. In another embodiment, the dry milled LMP powder has a d50 of <15 pm, <13 pm, <12 pm, <11 pm or <10 pm.

[0048] In an embodiment, the dry milled LMP powder may have d50 ranging from about 500 nm to about 30 pm. More specifically, the d50 range may be from about 800 nm to about 25 pm, about 750 nm to about 25 pm about 1000 nm to about 20 pm, about 5 pm to about 20 pm, about 5 pm to about 15 pm, or about 5 pm to about 10 pm.

[0049] The dry milled LMP powder may have a d50 ranging from about 400 to about 800 nm, about 450 to about 750 nm, about 400 to about 750 nm, about 400 to about 750 nm, about 400 to about 600 nm or about 400 to about 500 nm.

[0050] Any apparatus which appears suitable to the person skilled in the art and allows sufficient shearing forces or turbulence to be generated to achieve intensive mixing and, at the same time, deagglomeration or a reduction in the size of the particles, resulting in a D90 value of less than 50 pm, can be used to carry out the dispersing or milling treatment according to the invention. Preferred apparatuses include but are not limited to dispersing means (with or without pump rotors), Ultraturrax, mills such as colloid mills or Manton-Gaulin mills, intensive mixers, centrifugal pumps, in-line mixers, mixing nozzles, such as injector nozzles, or ultrasound appliances. Apparatuses that function in a similar way can be utilized and are known per se to the person skilled in the art. The settings required to obtain the desired effect on the mean particle size for the olivine-type LMP material can be determined using routine tests according to the particular type of apparatus.

[0051] In many cases, as part of the milling treatment according to the invention, mechanical power optionally in the form of crushing, grinding, and / or impacting is introduced into the olivine-type LMP material to reduce the particle size. This introduction of power can be determined in a known way for the particular apparatus, for example using the formula P=27cnM, where M represents the torque and n represents the rotational speed, when using an Ultraturrax stirrer.

[0052] Further, according to the methods described herein the dry milled non- stoichiometrically balanced LMP material and ion mixture forms a wet-milled slurry. The wet- milled slurry leads to the formation of an intimate admixture of solids and further reduces the average d50 value of the mixture, wherein the wet-milled slurry is dried to remove the liquid medium. In an embodiment, the wet-milled slurry is dried to yield primary particles including the particles of the olivine-type LMP material and the ion source.

[0053] The liquid medium used in the wet-milling process can be one or more of organic or inorganic solvents known in the art. Optionally, non-aqueous solvents can also be utilized. The organic solvent is selected from the group consisting of methanol, ethanol, isopropanol, 2- butanol, acetone, 2-butanone, and any combination thereof. In an embodiment, the liquid medium is water.

[0054] The liquid medium is removed by evaporation to recover the solids and / or the primary particles. In an embodiment, the liquid is removed from the wet-milled slurry any method known to one skilled in the art. Non-limiting examples of the drying method include spray drying, air drying, or vacuum drying.

[0055] The liquid medium can be removed by spray drying. The process of spray drying can minimize the separation of phases during drying. It provides favorable morphologies of the dried solids that enhance their handling characteristics (e.g., “flowability”). It further involves atomizing a liquid slurry containing active materials, binders, and additives into fine droplets, which are rapidly dried to form spherical particles. The resulting powder exhibits controlled particle size distribution and excellent morphology, making it ideal for electrode fabrication. The spray drying process allows precise control over particle size, achieves homogenous mixing, maximizes surface area, and uniformly distributes the individual particles.

[0056] In an embodiment, the desired spray drying inlet temperature ranges between about 50 °C and about 500 °C. More specifically, about 50 °C to about 300 °C, about 50 °C to about 250 °C, about 50 °C to about 200 °C or about 100 °C to about 250 °C. The desired spray drying inlet temperature may range between about 100 °C to about 500 °C, about 100 °C to about 400 °C, or about 100 °C to about 300 °C, about 50 °C to about 180 °C, about 100 °C to about 180 °C, or about 150 °C to about 180 °C. The preferable spray drying inlet temperature is about 140 °C, about 150 °C or 160 °C.

[0057] The desired spray drying outlet temperature is about 50 °C to about 500 °C, about 50 °C to about 300 °C, about 50 °C to about 250 °C, about 50 °C to about 200 °C, about 80 °C to about 250 °C, about 80 °C to about 150 °C, about 90 °C to about 125 °C, or about 95 °C to about 150 °C, about 80 °C to about 120 °C, about 90 °C to about 110 °C, or about 100 °C to about 110 °C. The preferable spray drying outlet temperature is about 90 °C, about 95 °C, about 100 °C or about 105 °C.

[0058] According to the methods provided herein spray drying yields primary particles comprising the olivine-type LMP material and the ion source, wherein the primary particles size distribution can be expressed as a d50 value. The average d50 value of the primary particles is about 50 nm to about 5000 nm.

[0059] The primary particles may have a d50 ranging from about 50 nm to about 4000 nm. More specifically, about 50 nm to about 3000 nm, about 100 nm to about 3000 nm, about 200 nm to about 1000 nm, about 500 nm to about 1000 nm, about 200 nm to about 5000 nm, about300 nm to about 3000 nm, about 400 nm to about 3000 nm, about 500 run to about 5000 nm, about 500 nm to about 2500 nm, about 500 nm to about 1500 nm, about 700 nm to about 2500 nm, about 800 nm to about 2500 nm, about 900 nm to about 3000 nm, about 1000 nm to about 3000 nm, about 1000 nm to about 2000 nm, about 1500 nm to about 3000 nm, about 1500 nm to about 2000 nm, or about 1500 nm to about 2500 nm.

[0060] The primary particles obtained via spray drying are calcinated to yield secondary particles. Calcination allows heating the primary particles under a controlled atmosphere, wherein the primary particles are present in a powdered form. It may be performed in a furnace, wherein the primary particles are subsequently heated in a furnace to a desired temperature. Calcination can also be performed using graphite or alumina crucible, wherein the powder comprising the primary particle has a depth can range from 0.2 cm to 15 cm.

[0061] Calcination is a method known to one skilled in the art. Calcination involves exposing the dried mixture to temperatures of about 700 - about 900 °C to remove any remaining water or binder from the drying process, and to fuse the metals tightly together. Precise temperature control throughout the process is critical, as it influences the electrochemical performance, optimizes the crystal structure, and particle size of the materials.

[0062] As known to a person skilled in the art, calcination involves a flow of inert gas, usually nitrogen or argon, is used to remove traces of oxygen as well as gaseous byproducts. The atmosphere can be made mildly reductive by inclusion of traces of reducing gases such as hydrogen, methane, or ammonia in the incoming gas flow. In some embodiments, the furnace interior containing the powder can be evacuated and placed under vacuum to remove ambient gases before refilling with inert, oxygen-free gases.

[0063] During the calcination process an internal temperature of the furnace is raised from room temperature at 0.5 to 15 °C / min continuously or with one or more intermediate hold temperature periods. In an embodiment, the furnace is heated in a nitrogen-purged furnace at 8°C / min.

[0064] In an embodiment, a final hold temperature ranges from about 500 °C to about 1000 °C. In an embodiment, a final hold temperature ranges from about 600 °C to about 800 °C. More specifically, the final hold temperature ranges from about 650 to about 850 °C. In an embodiment, a final hold temperature is about 650 °C to about 750 °C. In another embodiment, a final hold temperature is about 680 °C to about 720 °C. In an embodiment, a final hold temperature is about 700 °C.

[0065] The desired calcination furnace temperature ranges from about 100 °C to about 10000 °C. More specifically, the furnace temperature ranges from about 200 °C to about 8000 °C, about 300 °C to about 5000 °C, about 300 °C to about 2000 °C, about 500 °C to about 1000 °C, about 100 °C to about 2000 °C, about 500 °C to about 1500 °C, about 600 °C to about 1000 °C, about 500 °C to about 1000 °C, about 600 °C to about 900 °C, or about 650 °C to about 850 °C. In an embodiment, the desired calcination furnace temperature is about 650 °C to about 850 °C.

[0066] According to the aspects of the invention, the final temperature may be held for about 0.5 to about 8 hours before cooling to a safe handling temperature, usually below 100 °C. The final temperature may be held for about 1 to about 4 hours. In an embodiment, the final temperature is held for about 1 hour.

[0067] Calcination produces secondary particles comprising the olivine-type LMP material includes stoichiometrically balanced lithium (L), transition metal (M), and phosphate (P). The stoichiometrically balanced LMP in the secondary particles is a compound having the formula, Lixi(M)x2(PO4) x3, wherein M is one or more of Fe and Mn and wherein 0.98<xl<1.02; 0.98 < x2 < 1.02; and 0.98 < x3 < 1.02. The stoichiometrically balanced LMP in the secondary particles may be a compound having the formula, Lixi(M)X2Ay(PO4) x3, wherein M is one or more of Fe and Mn and wherein 0.98<xl<1.02; 0.98 < x2 < 1.02; 0.98 < x3 < 1.02 and y is 0.0 to 0.1.

[0068] In an embodiment, the secondary particles may have a d50 ranging from about 50 nm to about 5000 nm in size. More specifically, the secondary particles may have a d50 ranging from about 100 nm to about 5000 nm, about 100 nm to about 3000 nm, about 200 nm to about 3000 nm, about 200 nm to about 1000 nm, about 500 nm to about 1000 nm, about 200 nm to about 5000 nm, about 300 nm to about 3000 nm, about 400 nm to about 3000 nm, about 500 nm to about 5000 nm, about 500 nm to about 2500 nm, about 500 nm to about 1500 nm, about 700 nm to about 2500 nm, about 800 nm to about 2500 nm, about 900 nm to about 3000 nm, about 1000 nm to about 3000 nm, about 1000 nm to about 2000 nm, about 1500 nm to about 3000 nm, about 1500 nm to about 2000 nm, or about 1500 nm to about 2500 nm.

[0069] Alternatively, the secondary particles may have a d50 ranging from about 50 nm to about 500 nm. More specifically, the secondary particles may have a d50 ranging from 100 nm to about 500 nm, about 100 nm to about 300 nm, about 200 nm to about 300 nm, about 200 nm to about 250 nm, about 200 nm to about 500 nm, about 50 nm to about 150 nm, about 70 nm to about 250 nm, about 80 nm to about 250 nm, about 90 nm to about 300 nm, about 100nm to about 300 nm, about 100 nm to about 200 nm, about 150 ran to about 300 nm, about 150 nm to about 200 nm, or about 150 nm to about 250 nm or 100 nm to about 300 nm.

[0070] Further, the secondary particles may have a d50 ranging from about 10 nm to about 500 nm. More specifically, the secondary particles may have a d50 ranging from about 50 nm to about 500 nm, about 50 nm to about 500 nm, about 80 nm to about 500 nm, about 80 nm to about 450 nm, about 100 nm to about 500 nm, about 100 nm to about 450 nm, about 100 nm to about 400 nm, about 120 nm to about 500 nm, about 120 nm to about 450 nm or about 150 nm to about 400 nm.

[0071] Optionally, the secondary particles may have a d50 ranging from about 10 nm to about 1000 nm. More specifically, the secondary particles may have a d50 ranging from about 50 nm to about 250 nm, about 80 nm to about 300 nm, about 100 nm to about 300 nm, about 120 nm to about 300 nm, about 150 nm to about 300 nm, about 180 nm to about 450 nm, about 180 nm to about 400 nm, about 200 nm to about 450 nm, about 200 nm to about 300 nm or about 100 nm to about 400 nm.

[0072] The secondary particles may have a d50 of about 50 nm, about 80 nm, about 100 nm, about 120 nm, about 150 nm, about 180 nm, about 200 nm, about 250 nm, about 300 nm, or about 350 nm. In some embodiments, the secondary particle diameter ranges from about 30 nm, about 90 nm, about 110 nm, about 120 nm, about 140 nm, about 160 nm, about 190 nm, about 220 nm, about 280 nm, about 310 nm, about 340 nm, about 380 nm or about 410 nm. In another embodiment, the secondary particles have a d50 of about 4500 nm, about 4000 nm, about 3000 nm, about 2000 nm, about 1500 nm, about 1800 nm, about 1500 nm, about 1000 nm, about 900 nm, or about 750 nm. The secondary particles may have a d50 of about 2800 nm, about 2500 nm, about 2800 nm, about 3100 nm, about 3400 nm, about 3800 nm or about 4100 nm.

[0073] In an embodiment, the secondary particles have a d50 ranging from about 50 nm to about 500 nm. In another embodiment, the secondary particles have a d50 ranging from about 100 nm to about 300 nm.

[0074] In another aspect of the invention the method further includes formulating a cathode sheet using the secondary particles comprising stoichiometrically balanced olivine-type LMP material. The secondary particles used herein have a d50 ranging from about 100 nm to about 1000 nm. More specifically, the secondary particles used herein have a d50 ranging from about 100 nm to about 800 nm, 150 nm to about 600 nm, 150 nm to about 450 nm, about 150 nm toabout 300 run. In another embodiment, the secondary particles have a d50 ranging from about 150 nm to about 200 nm.

[0075] The method of formulating the cathode further includes adding one or more additional compounds comprising at least one element, wherein the one or more additional compounds is added in an amount that does not alter the stoichiometry of the secondary particles. As understood herein, an amount of the at least one element also does not alter the overall stoichiometry. Further, the at least one of the elements may be selected from the group consisting of magnesium, scandium, titanium, vanadium, chromium, cobalt, nickel, zinc, molybdenum, niobium, tungsten, aluminum, silicon, tin, and any combination thereof.

[0076] Alternatively, the additional compound added during the cathode making step can be a carbon-containing compound selected from an aromatic hydrocarbon compound including an alcohol, an acid, or a ketone. The aromatic hydrocarbon compound may include toluene, p- xylene, asphalt, or paraffin oil. Finally, a gas containing carbon atom may be utilized as a carbon-containing compound. The gas containing compound may include ethylene, methane, acetylene, carbon monoxide or the like.

[0077] The carbon-containing compound may be ascorbic acid, malic acid, tartaric acid, succinic acid, fumaric acid, citric acid, oxalic acid, gluconic acid, or lauric acid. Further, the carbon-containing compound may include carbon nanotubes, graphene, graphite, or carbon black.

[0078] Another source of the carbon-containing compound includes sugars including but not limited to sucrose, glucose, dextrose, fructose, lactose, or maltodextrin. In an embodiment, the carbon-containing compound may include organic polymers comprising polyethylene, polypropylene, polystyrene, polyethylene glycol, polyvinylpyrrolidone, polyvinyl alcohol, polyvinylpyrrolidone, polyacrylonitrile, polymethyl methacrylate, polyurethane, polyacrylamide, poly(acrylic acid), polyethylene oxide, poly(ethylene imine), carboxylmethyl cellulose, hydroxypropyl cellulose, polyethylene oxide, alkylated polyethylene oxide, crosslinked polyethylene oxide, polyvinyl ether, poly(methyl methacrylate), polyvinylidene fluoride, a copolymer of polyhexafluoropropylene and polyvinylidene fluoride, poly(ethyl acrylate), polytetrafluoro ethylene, polyvinyl chloride, polyacrylonitrile, derivatives, blends, or copolymers thereof.

[0079] In an embodiment, the carbon-containing compound is preferably polyvinylpyrrolidone (PVP, (CeHgNO)^). PVP is used to obtain improved stability and rate capability. During thesynthesis steps, the decomposition of PVP can cause carbon material to form on the electrode surface, resulting in an improved electrical conductivity of the active material. In addition, a reducing atmosphere, is generated by the decomposition of PVP, which potentially induces an oxygen loss. In an embodiment, PVP reduces surface area and changes morphology of the cathode material.

[0080] In another aspect of the invention, the carbon-containing compound can be selected from the group consisting of organic carbon sources, including sucrose, glucose, lactose, maltodextrin, soluble starch, polymers (e.g. poly(ethylene glycol), poly(vinyl alcohol), poly(acrylic acid), polyvinyl pyrrolidone), vinyl alcohol, acrylic acid, citric acid, oxalic acid, and lauric acid; inorganic carbons; urea; and combinations thereof.

[0081] The carbon-containing compound may be added in an amount equal to about 0.0 to about 0.2 wt%, based on the total weight of the olivine-type LMP material. In an embodiment, the one or more additional compounds may added in an amount equal to 0.00 wt% to 0.01 wt%, 0.01 wt% to 0.02 wt%, 0.02 wt% to 0.03 wt%, 0.02 wt% to 0.04 wt%, 0.03 wt% to 0.04 wt%, 0.04 wt% to 0.2 wt%, 0.05 wt% to 0.2 wt%, 0.05 wt% to 0.1 wt%, 0.08 wt% to 0.15 wt%, or 0.1 wt% to 0.2 wt%.

[0082] Another aspect of the invention includes a stoichiometrically balanced olivine-type lithium-transition metal -phosphate (LMP) cathode material useful in a lithium-ion battery synthesized according to the following steps: providing a source of a non-stoichiometrically adjusted olivine-type LMP material; adding ion sources for a subsequent restoration of stoichiometric 1:1:1 balance; reducing a size of particles of non-stoichiometrically adjusted olivine-type LMP material down to micron / sub-micron scale by wet milling a slurry comprising the particles of non-stoichiometrically adjusted olivine-type LMP material, the ion sources, and a liquid; removing the liquid from the wet-milled slurry to create a dry mixture of micron / sub- micron scale non-stoichiometrically adjusted olivine-type LMP material particles, and ion sources; and calcining the dry mixture of micron / sub-micron scale non-stoichiometrically adjusted olivine-type LMP material particles under a controlled atmosphere less than a temperature in which the micron scale non-stoichiometrically adjusted olivine-type LMP material particles can re-fuse, and sufficient for breaking down the ion sources to integrate them into a resultingapproximately 1:1:1 stoichiometrically balanced, micron / sub-micron scale particles of the useful final cathode material.

[0083] As described herein, the olivine-type lithium-transition metal-phosphate (LMP) material comprises lithium iron phosphate (LFP) and lithium manganese iron phosphate (LMFP).

[0084] Also provided herein is a composition comprising stoichiometrically balanced olivinetype LMP material made from the methods described herein.

[0085] While the embodiments provided herein describe materials synthesized using solid- state and fusion synthesis, one of ordinary skill in the art would recognize that the present technology is applicable to materials synthesized through various other synthesis routes including, but not limited to, melting, fusion, solid-state, hydrothermal, etc. Similarly, one of ordinary skill in the art would recognize that the present technology is applicable to off- stoichiometric material according to its chemical composition in addition to (or in place of) the crystallographic phase of the material. For example, one of ordinary skill in the art would recognize that the material can be an amorphous material, and the chemical stoichiometry of the amorphous material can be adjusted using the present technology.

[0086] EXAMPLES

[0087] It will be appreciated that the following examples are intended to illustrate but not to limit the present disclosure. Various other examples and modifications of the foregoing description and examples will be apparent to a person skilled in the art after reading the disclosure without departing from the spirit and scope of the disclosure, and it is intended that all such examples or modifications be included within the scope of the appended claims.

[0088] At first, the following course of experiments were performed to validate the impact of stoichiometric composition on the impurity content of the final product. This also shows that the expected composition, calculated from the compositions of the ingredients, aligns closely with the observed composition of the product measured by ICP-OES. It further (1) demonstrates the requisite synthesis quality and precision to make fine adjustments to stoichiometry, done throughout this disclosure, and (2) conclusively demonstrates that stoichiometry measurements from ICP-OES align with impurity detection via X-ray diffraction (XRD) measurements.

[0089] Example 1

[0090] Starting Material: A fusion-synthesized sample of LMFP was generated for use.Elemental analysis of the sample by ICP-OES indicated a Li:TM:P molar ratio of 0.962:0.939:1.

[0091] A compositional “ladder study” was performed using the above generated fused sample. In the study, seven heat treated samples with varying target Li:TM:P ratios were prepared using the following method. For each heat treated sample, a portion of the fused sample was ground and jet milled until 99% of the mass had a particle size less than 11.2 pm as measured by dry laser diffraction particle size analysis. This dry milled powder (6.00 g) was combined with LiiCCh (amount varies), Mn(C2H3O2)2«2H2O (amount varies), and Fe(C C>4)*H2O (amount varies). Sucrose (0.36 g), polyethylene glycol) 6000 (0.12 g), and distilled water (14 g) were also added, and the resulting slurry was milled in a Fritsch planetary mill with 3 mm beads for 36 minutes.

[0092] For each heat treated sample, before synthesis, an expected Li:P ratio is calculated by dividing the total moles of lithium, coming from the fused sample and any Li2CO3 added, by the total moles of phosphorus, coming from the fused sample. See Fig. 1 A. An expected TM:P ratio is calculated analogously, where the total transition metal content comes from the fused sample, Mn(C2H3O2)2«2H2O, and Fe(C2O4)«H2O in the sample. See Fig. IB. For each sample, observed Li:P and TM:P ratios are measured after heat treatment using ICP-OES. See Fig. 1 A and Fig. IB shows that the expected and observed ratios align closely, demonstrating that transition metal and lithium added using the invention disclosed herein indeed integrate into the heat treated product.

[0093] Moreover, we show here that the stoichiometric correction additives react with the fused material. Figure 2, (a) shows the observed stoichiometries of the original fused sample and the seven heat treated samples, labeled A-G. Panel (b) shows the XRD diffractograms of all seven heat treated samples, demonstrating that all are predominantly, if not entirely, composed of LMFP. (Traces are offset vertically for clarity). Panel (c) is an inset highlighting three classes of impurities: LisPC (23.2° and 24.8°), Fe2P (26.5°), and transition metal pyrophosphates (29.1° and 30.4°). Samples A and B, being deficient in lithium, have pyrophosphate impurities as expected. Sample C, being rich in transition metal, shows a marked Fe2P impurity as expected. Samples E and F have sufficient excess lithum to show crystalline Li3PO4 impurities, as expected. Though sample E deviates from the formulastoichiometry of Li:TM:P = 1:1:1, it does not show any visible impurities in XRD, suggesting that any impurities present are not sufficiently crystalline to diffract in XRD measurements.

[0094] In addition, the following examples apply the above synthetic and analytical techniques in Example 1 to stoichiometrically correct fusion and solid-state synthesized samples into useful cathode materials.

[0095] Example 2

[0096] Material: A fusion-synthesized sample of LMFP was generated for use. Elemental analysis of the sample by ICP-OES (Li 4.207%, Mn 19.284%, Fe 13.899%, P 20.309%) indicated a Li:TM:P molar ratio of 0.925:0.915:1.

[0097] Reductive calcination of this material resulted in a mass containing iron pyrophosphate and manganese pyrophosphate impurities observable by XRD. The solid was ground and jet milled until 99% of the mass had a particle size less than 11.2 pm as measured by dry laser diffraction particle size analysis. This dry milled powder (24.00 g) was combined with Li2CO3 (0.616 g), Mn(C2H3O2)2*2H2O (1.809 g), and Fe(C2O4)«H2O (0.238 g). These inclusions will simultaneously adjust the lithium, iron, and manganese content of the fused sample, to target Li:TM:P ratios of 1.03:0.97:1.00 with a Mn:Fe ratio of 0.60:0.40. Deionized water (56 g) was also added, and the resulting slurry was milled in a Fritsch planetary mill with 0.5 mm beads for 4 h. The slurry was dried in a Yamato spray dryer with an atomizing pressure, blower rate, inlet temperature, and outlet temperature of 0.2 MPa, 0.5 m3 / min, 160°C, and 105°C, respectively, and 24.16 g of spray dried powder was recovered. A 10.0 g portion of the spray dried powder in a graphite crucible was heated in a nitrogen-purged Linn furnace at 8°C / min to a hold temperature of 700 °C for 1 h, then cooled, to provide 8.5 g of a fine black powder.

[0098] The XRD diffractogram of the product shows phase-pure LMFP with no residual pyrophosphate. Figure 3, panel (a) shows the XRD diffractograms of the fused sample and heat treated product. (Traces are offset vertically for clarity). Panel (b) is an inset highlighting three classes of impurities: Li3PO4 (23.2° and 24.8°), FeiP (26.5°), and transition metal pyrophosphates (29.1° and 30.4°). The fused sample, being deficient in lithium, has pyrophosphate impurities, as expected. The stoichiometric correction and heat treatment relieve these impurities, resulting in a phase-pure sample as measured by XRD. Though the product deviates from the formula stoichiometry of Li:TM:P = 1:1:1, it does not show any visible impurities in XRD, suggesting that any impurities present are not sufficiently crystalline todiffract in XRD measurements. Any trace impurities present do not deleteriously affect cathode performance.

[0099] Further, the powder was formed into a cathode sheet by formulation into a 95:2.5:2.5 slurry with conductive carbon additive and poly(vinylidene fluoride) binder combined in NMP which was coated and dried onto an aluminum foil backing. Circular punches of this sheet were assembled into coin cells with Celgard separators, lithium metal anodes, and 1.2M LiPF6 in EC:EMC (3:7 w / w) plus 2wt% vinylene carbonate electrolyte. Electrochemical testing of these cells indicated discharge capacities of 156 mAh / g at C / 25 and 143 mAh / g at 1C rates, demonstrating useful performance of these materials in lithium ion batteries. See Fig. 4.

[0100] Example 3

[0101] Material: A fusion-synthesized sample of LMFP was generated for use. Elemental analysis of the sample by ICP-OES (Li 4.207%, Mn 19.284%, Fe 13.899%, P 20.309%) indicated a Li:TM:P molar ratio of 0.925:0.915:1.

[0102] Reductive calcination of this material resulted in a mass containing iron pyrophosphate and manganese pyrophosphate impurities observable by XRD. The solid was ground and jet milled until 99% of the mass had a particle size less than 11.2 um as measured by dry laser diffraction particle size analysis. This dry milled powder (24.00 g) was combined with Li2CO3 (0.616 g), Mn(C2O4)«2H2O (1.345 g), and Fe(C2O4)«H2O (0.238 g). These inclusions will simultaneously adjust the lithium, iron, and manganese content of the fused sample, to target Li:TM:P ratios of 1.03:0.97:1.00 with a Mn:Fe ratio of 0.60:0.40. Titanium dioxide nanopowder (0.072 g) and deionized water (56 g) were also added, and the resulting slurry was milled in a Fritsch planetary mill with 3 mm beads for 4 h. The slurry was dried in a Yamato spray dryer with an atomizing pressure, blower rate, inlet temperature, and outlet temperature of 0.2 MPa, 0.5 m3 / min, 160°C, and 105°C, respectively, and 24.10 g of spray dried powder was recovered. A 10.0 g portion of the spray dried powder in a graphite crucible was heated in a nitrogen-purged Linn furnace at 8°C / min to a hold temperature of 700 °C for 1 h, then cooled, to provide 8.6 g of a fine black powder.

[0103] The XRD diffractogram of the product shows phase-pure LMFP with no residual pyrophosphate, but with trace impurities of L13PO4 on account of the excess lithium added. The powder was formed into a cathode sheet by formulation into a 95:2.5:2.5 slurry with conductive carbon additive and poly(vinylidene fluoride) binder combined in NMP which was coated and dried onto an aluminum foil backing. Circular punches of this sheet were assembled into coincells with Celgard separators, lithium metal anodes, and 1.2M LiPF6 in EC:EMC (3:7 w / w) plus 2wt% vinylene carbonate electrolyte. Electrochemical testing of these cells indicated discharge capacities of 148 mAh / g at C / 25 and 132 mAh / g at 1C rates, demonstrating useful performance of these materials in lithium ion batteries. See Fig. 5.

[0104] Example 4

[0105] Material: A fusion-synthesized sample of LMFP was generated for use. Elemental analysis of the sample by ICP-OES (Li 4.207%, Mn 19.284%, Fe 13.899%, P 20.309%) indicated a Li:TM:P molar ratio of 0.925:0.915:1.

[0106] Reductive calcination of this material resulted in a mass containing iron pyrophosphate and manganese pyrophosphate impurities observable by XRD. The solid was ground and jet milled until 99% of the mass had a particle size less than 11.2 pm as measured by dry laser diffraction particle size analysis. This dry milled powder (24.00 g) was combined with Li2CO3 (0.616 g), Mn(C2H3O2)2«2H2O (1.809 g), and Fe(C2O4)«H2O (0.238 g). These inclusions will simultaneously adjust the lithium, iron, and manganese content of the fused sample, to target Li:TM:P ratios of 1.03:0.97:1.00 with a Mn:Fe ratio of 0.60:0.40. Deionized water (56 g) was also added, and the resulting slurry was milled in a Fritsch planetary mill with 0.3 mm beads for 4 h. The slurry was dried in a Yamato spray dryer with an atomizing pressure, blower rate, inlet temperature, and outlet temperature of 0.2 MPa, 0.5 m3 / min, 160°C, and 105°C, respectively, and 23.39 g of spray dried powder was recovered. A 12.0 g portion of the spray dried powder in a graphite crucible was heated in a nitrogen-purged Linn furnace at 8°C / min to a hold temperature of 700 °C for 1 h, then cooled, to provide 10.2 g of a fine black powder.

[0107] The XRD diffractogram of the product shows phase-pure LMFP with no residual pyrophosphate. The powder was formed into a cathode sheet by formulation into a 95:2.5:2.5 slurry with conductive carbon additive and poly(vinylidene fluoride) binder combined in NMP which was coated and dried onto an aluminum foil backing. Circular punches of this sheet were assembled into coin cells with Celgard separators, lithium metal anodes, and 1.2M LiPF6 in EC:EMC (3:7 w / w) plus 2wt% vinylene carbonate electrolyte. Electrochemical testing of these cells indicated discharge capacities of 156 mAh / g at C / 25 and 138 mAh / g at 1C rates, demonstrating useful performance of these materials in lithium ion batteries. See Fig. 6.

[0108] Example 5

[0109] Material: Methods: Results: A fusion-synthesized sample of LMFP was generated for use. Elemental analysis of the sample by ICP-OES indicated a Li:TM:P molar ratio of 1.052:0.954:1.

[0110] Reductive calcination of this material resulted in a mass containing lithium phosphate impurities observable by XRD. The solid was ground and jet milled until 99% of the mass had a particle size less than 11.2 um as measured by dry laser diffraction particle size analysis. This dry milled powder (24.00 g) was combined with ammonium phosphate dibasic (1.212 g), Mn3<D4 (0.497 g), and FeiCh (0.342 g). These inclusions will simultaneously adjust the iron, manganese, and phosphorus content of the fused sample, to target Li:TM:P ratios of 0.992:0.966:1.000 with a Mn:Fe ratio of 0.60:0.40. Glucose (0.54 g), sucrose (0.54 g), poly(ethylene glycol) 6000 (0.96 g), and deionized water (56 g) were also added, and the resulting slurry was milled in a Fritsch planetary mill with 0.5 mm beads for 4 h. The slurry was dried in a Yamato spray dryer with an atomizing pressure, blower rate, inlet temperature, and outlet temperature of 0.2 MPa, 0.5 m3 / min, 160°C, and 105°C, respectively, and 23.39 g of spray dried powder was recovered. A 12.0 g portion of the spray dried powder in a graphite crucible was heated in a nitrogen-purged Linn furnace at 8°C / min to a hold temperature of 700 °C for 1 h, then cooled, to provide 10.7 g of a fine black powder.[oni] The XRD diffractogram of the product shows phase-pure LMFP with no residual lithium phosphate.

[0112] Example 6

[0113] Material: A fusion-synthesized sample of LMFP was generated for use. Elemental analysis of the sample by ICP-OES indicated a Li:TM:P molar ratio of 1.052:0.954:1.

[0114] Reductive calcination of this material resulted in a mass containing lithium phosphate impurities observable by XRD. The solid was ground and jet milled until 99% of the mass had a particle size less than 11.2 pm as measured by dry laser diffraction particle size analysis. This dry milled powder (272.00 g) was combined with anhydrous iron phosphate (10.37 g) and MnsO4 (6.54 g). These inclusions will simultaneously adjust the iron, manganese, and phosphorus content of the fused sample, to target Li:TM:P ratios of 1.012:0.976:1.000 with a Mn:Fe ratio of 0.60:0.40. Glucose (0.54 g), sucrose (0.54 g), poly(ethylene glycol) 6000 (0.96 g), and deionized water (56 g) were also added, and the resulting slurry was milled in a Fritsch planetary mill with 0.5 mm beads for 4 h. The slurry was dried in a Yamato spray dryer with an atomizing pressure, blower rate, inlet temperature, and outlet temperature of 0.2 MPa, 0.5m3 / min, 160°C, and 105°C, respectively, and 23.39 g of spray dried powder was recovered. A 12.0 g portion of the spray dried powder in a graphite crucible was heated in a nitrogen-purged Linn furnace at 8°C / min to a hold temperature of 700 °C for 2 h, then cooled, to provide 10.7 g of a fine black powder.

[0115] The XRD diffractogram of the product shows phase-pure LMFP with no residual lithium phosphate. The powder was formed into a cathode sheet by formulation into a 95:2.5:2.5 slurry with conductive carbon additive and poly(vinylidene fluoride) binder combined in NMP which was coated and dried onto an aluminum foil backing. Circular punches of this sheet were assembled into coin cells with Celgard separators, lithium metal anodes, and 1.2M LiPF6 in EC:EMC (3:7 w / w) plus 2wt% vinylene carbonate electrolyte. Electrochemical testing of these cells indicated discharge capacities of 152 mAh / g at C / 25 and 136 mAh / g at 1C rates, demonstrating useful performance of these materials in lithium ion batteries. See Fig. 7.

[0116] Example 7

[0117] Material: A fusion-synthesized sample of LMFP. Elemental analysis of the sample by ICP-OES indicated a Li:TM:P molar ratio of 0.921:0.957:1.

[0118] Reductive calcination of this material resulted in a mass containing iron pyrophosphate and manganese pyrophosphate impurities observable by XRD. The solid was ground and jet milled until 99% of the mass had a particle size less than 11.2 pm as measured by dry laser diffraction particle size analysis. This dry milled powder (12.00 g) was combined with Li3PO4 (0.33 g), iron lactate dihydrate (0.33 g), and manganese acetate tetrahydrate (0.48 g). These inclusions will simultaneously adjust the lithium, iron, manganese, and phosphorus content of the fused sample, to target Li:TM:P ratios of 0.994:0.962: 1.000 with a Mn:Fe ratio of 0.58:0.42. Glucose (0.48 g), poly(ethylene glycol) 6000 (0.48 g), gluconic acid (0.24 g) and deionized water (28 g) were also added, and the resulting slurry was milled in a Fritsch planetary mill with 1 mm beads for 4 h. The slurry was dried in a Rotovap vacuum evaporator at 45°C and 2 mTorr for 1 h. A 13 g portion of the dried powder in a graphite crucible was heated in a nitrogen-purged Linn furnace at 8°C / min to a hold temperature of 700 °C for 2 h, then cooled, to provide a fine black powder.

[0119] The XRD diffractogram of the product shows phase-pure LMFP with no residual pyrophosphate.

[0120] Example 8

[0121] Material: A solid-state synthesized sample of LMFP. Elemental composition analysis of the sample by ICP indicated a Li:TM:P molar ratio of 0.95:0.97:1.00.

[0122] This powder (136.00 g) was combined with lithium carbonate (1.7 g), iron oxalate dihydrate (1.55 g), manganese oxalate dihydrate (2.32 g). These inclusions will simultaneously adjust the lithum, iron, and manganese content of the fused sample, to target Li:TM:P ratios of 1.006:0.957:1.000 with a Mn:Fe ratio of 0.61:0.39. Glucose (5.44 g), poly(ethylene glycol) 6000 (5.44 g), titanium(IV) oxide anatase (0.408 g), polyvinylpyrrolidone (1.36 g) and deionized water (317 g) were also added. The resulting slurry was milled in a horizontal disk mill with 0.3mm beads for 1 h and the slurry was then spray dried. A 12 g portion of the spray dried powder in a graphite crucible was heated in a nitrogen-purged Linn furnace at 8°C / min to a hold temperature of 700 °C for 2 h, then cooled, to provide 11 g of a fine black powder.

[0123] The XRD diffractogram of the product shows phase-pure LMFP with no residual pyrophosphate. The powder was formed into a cathode sheet by formulation into a 90:5:5 slurry with conductive carbon additive and poly (vinylidene fluoride) binder combined in NMP which was coated and dried onto an aluminum foil backing. Circular punches of this sheet were assembled into coin cells with Celgard separators, lithium metal anodes, and 1.2M LiPF6 in EC:EMC (3:7 w / w) plus 2wt% vinylene carbonate electrolyte. Electrochemical testing of these cells indicated discharge capacities of 156 mAh / g at C / 25 and 138 mAh / g at 1C rates, demonstrating useful performance of these materials in lithium ion batteries. See Fig. 8.

[0124] Example 9

[0125] Material: A fusion-synthesized sample of LMFP was generated. The elemental analysis of the sample by ICP-OES indicated a Li:TM:P molar ratio of 0.921:0.957:1 (“Sample A”).

[0126] Reductive calcination of this material resulted in a mass containing iron pyrophosphate and manganese pyrophosphate impurities observable by XRD. The solid was ground and jet milled until 99% of the mass had a particle size less than 11.2 pm as measured by dry laser diffraction particle size analysis. This dry milled powder (12.37 g) was combined with two other fusion-synthesized samples, milled in a similar manner, with the following compositions and masses:

[0127] 8.12 g of a sample with a Li:TM:P molar ratio of 1.052:0.954:1.000 (“Sample B”);

[0128] 9.52 g of a sample with a Li:TM:P molar ratio of 0.999:0.986:1.000 (“Sample C”).

[0129] Because all three samples contain Li, Fe, Mn, and P, the composition of three of these elements may be adjusted independently, while the fourth remains constrained. Alternatively, the Li, TM, and P compositions may be adjusted independently, where the TM content is the sum of the Fe and Mn compositions. In the given example, the specified admixture of samples A, B, and C to yield a calculated Li:TM:P ratio of 0.981 :0.965: 1.000 in the final product (see figure, below). See Fig. 9. Glucose (0.2 g), poly(ethylene glycol) 6000 (0.2 g), polyvinylpyrrolidone (0.1 g), and deionized water (14 g) were also added, and the resulting slurry was milled in a Fritsch planetary mill with 1 mm beads for 4 h. The slurry was dried in a Rotovap vacuum evaporator at 45°C and 2 mTorr for 1 h. A 13 g portion of the dried powder in a graphite crucible was heated in a nitrogen-purged Linn furnace at 8°C / min to a hold temperature of 700 °C for 2 h, then cooled, to provide a fine black powder.

[0130] XRD analysis of the final product clearly demonstrates that a phase-pure, useful cathode material can be derived using this method. Figure 10, panel (a) shows the XRD diffractograms of samples A, B, and C after reductive calcination, as well as the product derived from the admixture. (Traces are offset vertically for clarity). Panel (b) is an inset highlighting three classes of impurities: Li3PO4 (23.2° and 24.8°), FeiP (26.5°), and transition metal pyrophosphates (29.1° and 30.4°). Samples A, being deficient in lithium, has pyrophosphate impurities, as expected. Sample B, being rich in lithium, shows crystalline LiaPC impurities, as expected. Sample C, having a Li:TM:P molar ratio close to 1 :1 :1, does not show any crystalline impurities. The product, with a Li:TM:P molar ratio of0.981 :0.965:l .000, likewise does not show any impurities, clearly demonstrating that the three fused species react with each other during calcination: if they did not react, the product would still contain pyrophosphate impurities from sample A and lithium phosphate impurities from sample B. Therefore, this procedure is able to remedy the off-stoichiometry of sample A, resulting in a useful cathode material.

[0131] In addition, following experiments were performed to identify the requisite amount of supplementary ions to add to a fusion-synthesized sample, by systematically varying the amount added across many experimental-scale samples and identifying a formulation which yields a phase-pure product.

[0132] Example 10

[0133] Reductive calcination of a fusion-synthesized sample as previously synthesized resulted in a mass containing iron pyrophosphate and manganese pyrophosphate impuritiesobservable by XRD. The solid was ground and jet milled until 99% of the mass had a particle size less than 11.2 pm as measured by dry laser diffraction particle size analysis. This dry milled powder (6.00 g) was combined with Li2CO3 (0.026 g), Mn(C2H3O2)2«2H2O (0.113 g), and Fe(C2O4)*H2O (0.055 g). Distilled water (14 g) was also added, and the resulting slurry was milled in a Fritsch planetary mill with 3 mm beads for 36 minutes. The slurry was dried in an IKA RV8 rotary evaporator and 6.43 g of dried powder was recovered. A 3.0 g portion of the spray dried powder in a graphite crucible was heated in a nitrogen-purged Linn furnace at 8°C / min to a hold temperature of 750 °C for 2 h, then cooled, to provide 2.73 g of a fine black powder.

[0134] The XRD diffractogram of the product shows residual pyrophosphate impurities, indicating that an insufficient amount of transition metal ions were added in the formulation.

[0135] Example 11

[0136] Reductive calcination of a fusion-synthesized sample as previously synthesized resulted in a mass containing iron pyrophosphate and manganese pyrophosphate impurities observable by XRD. The solid was ground and jet milled until 99% of the mass had a particle size less than 11.2 pm as measured by dry laser diffraction particle size analysis. This dry milled powder (6.00 g) was combined with Li2CO3 (0.026 g), Mn(C2H3O2)2«2H2O (0.451 g), and Fe(C2O4)«H2O (0.221 g). Distilled water (14 g) was also added, and the resulting slurry was milled in a Fritsch planetary mill with 3 mm beads for 36 minutes. The slurry was dried in an IKA RV8 rotary evaporator and 6.94 g of dried powder was recovered. A 3.0 g portion of the spray dried powder in a graphite crucible was heated in a nitrogen-purged Linn furnace at 8°C / min to a hold temperature of 750 °C for 2 h, then cooled, to provide 2.59 g of a fine black powder.

[0137] The XRD diffractogram of the product shows iron metal and lithium phosphate impurities, indicating that an excess of transition metal ions and of lithium ions was added in the formulation.

[0138] Example 12

[0139] Reductive calcination of a fusion-synthesized sample as previously synthesized resulted in a mass containing iron pyrophosphate and manganese pyrophosphate impurities observable by XRD. The solid was ground and jet milled until 99% of the mass had a particle size less than 11.2 pm as measured by dry laser diffraction particle size analysis. This dry milled powder (6.00 g) was combined with Li2CO3 (0.026 g), Mn(C2H3O2)2«2H2O (0.407 g),and Fe(C2O4)«H2O (0.249 g). Distilled water (14 g) was also added, and the resulting slurry was milled in a Fritsch planetary mill with 3 mm beads for 36 minutes. The slurry was dried in an IKA RV8 rotary evaporator and 6.87 g of dried powder was recovered. A 3.0 g portion of the spray dried powder in a graphite crucible was heated in a nitrogen-purged Linn furnace at 8°C / min to a hold temperature of 750 °C for 2 h, then cooled, to provide 2.63 g of a fine black powder.

[0140] The XRD diffractogram of the product shows iron metal impurities, indicating that an excess amount of transition metal ions was added in the formulation.

[0141] Example 13

[0142] Reductive calcination of a fusion-synthesized sample as previously synthesized resulted in a mass containing iron pyrophosphate and manganese pyrophosphate impurities observable by XRD. The solid was ground and jet milled until 99% of the mass had a particle size less than 11.2 pm as measured by dry laser diffraction particle size analysis. This dry milled powder (6.00 g) was combined with Li2CO3 (0.103 g), Mn(C2H3O2)2«2H2O (0.113 g), and Fe(C2O4)*H2O (0.055 g). Distilled water (14 g) was also added, and the resulting slurry was milled in a Fritsch planetary mill with 3 mm beads for 36 minutes. The slurry was dried in an IKA RV8 rotary evaporator and 6.56 g of dried powder was recovered. A 3.0 g portion of the spray dried powder in a graphite crucible was heated in a nitrogen-purged Linn furnace at 8°C / min to a hold temperature of 750 °C for 2 h, then cooled, to provide 2.79 g of a fine black powder.

[0143] The XRD diffractogram of the product shows lithium phosphate impurities, indicating that an excess of lithium ions was added in the formulation.

[0144] Example 14:

[0145] Methods: Reductive calcination of a fusion-synthesized sample as previously synthesized resulted in a mass containing iron pyrophosphate and manganese pyrophosphate impurities observable by XRD. The solid was ground and jet milled until 99% of the mass had a particle size less than 11.2 pm as measured by dry laser diffraction particle size analysis. This dry milled powder (6.00 g) was combined with Li2CO3 (0.052 g), Mn(C2H3O2)2«2H2O (0.113 g), and Fe(C2O4)*H2O (0.055 g). Distilled water (14 g) was also added, and the resulting slurry was milled in a Fritsch planetary mill with 3 mm beads for 36 minutes. The slurry was dried in an IKA RV8 rotary evaporator and 6.63 g of dried powder was recovered. A 3.0 g portion of the spray dried powder in a graphite crucible was heated in a nitrogen-purged Linnfurnace at 8°C / min to a hold temperature of 750 °C for 2 h, then cooled, to provide 2.70 g of a fine black powder.

[0146] The XRD diffractogram of the product residual pyrophosphate impurities, indicating that an insufficient amount of transition metal ions were added in the formulation.

[0147] Although the invention has been described with reference to the disclosed embodiments, those skilled in the art will readily appreciate that the specific examples and studies detailed above are only illustrative of the invention. It should be understood that various modifications can be made without departing from the spirit of the invention.DEFINITIONS

[0148] All publications, patents and patent applications cited herein, whether supra or infra, are hereby incorporated by reference in their entirety to the same extent as if each individual publication, patent, or patent application were specifically and individually indicated to be incorporated by reference.

[0149] The terms “comprising,” “including,” “having” and their derivatives, are not intended to exclude the presence of any additional component, step, or procedure, whether or not the same is specifically disclosed. In order to avoid any doubt, all compositions claimed through use of the term “comprising” may include any additional additive, adjuvant, or compound, whether polymeric or otherwise, unless stated to the contrary.

[0150] The term “or” unless stated otherwise, refers to the listed members individually as well as in any combination. Use of the singular includes use of the plural and vice versa.

[0151] The terms “a,” “an,” “the” and similar referents used in the context of describing the inventive features (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. Thus, for example, reference to a “starch” may include one, two or more starches.

[0152] The term “method” refers to a sequence of steps performed to complete a process.

[0153] The term “composition” refers to a mixture of materials which comprise the composition, as well as reaction products and decomposition products formed from the materials of the composition.

[0154] The term “<” as used herein refers to a quantitative measure which is interpreted as “less than or equal to.”

[0155] The term “micron,” “micrometer,” “gm” or “micrometers” refers to refers to a unit of measure which is equal to one thousand meters. The term “sub-micron” refers to “to a quantitative measure less than a micron or less than 1 micrometer.” With respect to the present invention the term is used to define particle size.

[0156] The term “nm,” “nanometers, “or “nanometer” refers to a unit of length which is one thousand-millionth of a meter. With respect to the present invention the term is used to define particle size.

[0157] The term “additives,” “additional compounds,” “agents” all refer to “one or more additional compounds,” as described herein.

[0158] The term “substantially free of’ used in reference to “oxidized impurities” refers to less than 5%, less than 1%, less than 0.5%, less than 0.2%, less than 0.1%, less than 0.99%, less than 0.09%, less than 0.08%, less than 0.05%, less than 0.01%.

[0159] The term “LMP” used in reference to olivine-type material refers to “lithium-transition metal-phosphate.” As used herein, “LFP” refers to “lithium iron phosphate.” As used herein, “LMFP” refers to “lithium manganese iron phosphate.”

[0160] “Capacity” of a battery or battery cell is a measure of the charge stored by the battery and is determined by the active materials contained in the battery. The capacity represents the maximum amount of charge that can be extracted from the battery under certain specified conditions. The battery has a discharge current in amperes that can be delivered over time. The capacity of the battery is given in ampere-hours (Ah).

[0161] “Gravimetric capacity” is the capacity per unit mass (mAh / g). Gravimetric capacity is also referred to as specific discharge capacity.

[0162] “D50” and / or “d50” as used herein is a measurement of the average particle size in a group of particles. For example, as used in reference to the size of particles in the LMP powder, dry milled particles, primary particles, and / or secondary particles.

[0163] Unless otherwise stated, all percentages, ratios, parts, and amounts used and described herein are by weight.

[0164] Numbers, percentages, ratios, or other values stated herein may include that value, and other values that are about or approximately the stated value, as would be appreciated by one of ordinary skill in the art. A stated value should therefore be interpreted broadly enough to encompass values that are at least close enough to the stated value to perform a desiredfunction or achieve a desired result, and / or values that round to the stated value. The stated values include at least the variation to be expected in a typical manufacturing process, and may include values that are within 25%, 15%, 10%, within 5%, within 1%, etc. of a stated value.

[0165] “wt%” as used herein refers to the percent ratio of the mass of the non-fluid particles or dissolved solids relative to the total mass of said mixture. For example, mass of the particles of ions, additional compounds, and / or dopants in a given mixture relative to the total mass of the olivine-type LMP material.

[0166] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. The initial definition provided for a group or term herein applies to that group or term throughout the present specification individually or as part of another group unless otherwise indicated.

Claims

CLAIMS1. A method for producing stoichiometrically balanced olivine-type lithium-transition metal-phosphate (LMP) materials, the method comprising: dry milling particles of a non-stoichiometric olivine-type LMP material to obtain a dry milled LMP powder; adding an ion source to the dry milled LMP powder to form a mixture, wherein the ion source comprises one or more of lithium ions, transition metal ions, and phosphate ions; milling the LMP powder and ion source mixture with a liquid medium to form a wet-milled slurry; drying the wet-milled slurry to yield primary particles comprising particles of the olivine-type LMP material, and the ion source; wherein the primary particles have a d50 ranging from about 50 nm to about 5000 nm; and calcining the primary particles to produce secondary particles comprising LMP having a d50 ranging from about 50 nm to about 5000 nm; wherein the ratio of LMP in the secondary particles is stoichiometrically balanced for the lithium (L), transition metal (M), and phosphate (P).

2. The method of claim 1, wherein the non-stoichiometric olivine-type LMP material is a compound having the formula:Lixl(M)x2(PO4)x3 wherein:M= one or more of Fe and Mn; and wherein one or more of xl, x2, and x3 are less than or equal to 0.98.

3. The method of claim 1, wherein the stoichiometrically balanced LMP in the secondary particles is a compound having the formula:Lixl (M)X2(PO4)X3 wherein:M= one or more of Fe and Mn;0.98 < xl < 1.02;0.98 < x2 < 1.02; and0.98 < x3 < 1.02.

4. The method of claim 1, wherein the step of adding an ion source to the dry milled LMP powder to form a mixture further comprises adding a dopant (A), wherein the dopant is selected from one or more of Mg, Sc, Ti, V, Cr, Co, Ni, Zn, Mo, Nb, W, Al, Si, and Sn.

5. The method of claim 1, wherein the stoichiometrically balanced LMP in the secondary particles is a compound having the formula:Lixl (M)X2 Ay(PO4)x3 wherein:M= one or more of Fe and Mn;0.98< xl < 1.02;0.98 < x2 < 1.02;0.98 < x3 < 1.02; and y = 0.0-0.1.

6. The method of claim 6, wherein the carbon-containing compound is selected from the group consisting of glucose, sucrose, lactose, maltodextrin, soluble starch, polyethylene glycol, vinyl alcohol, acrylic acid, citric acid, oxalic acid, lauric acid, urea, and combinations thereof.

7. The method of claim 1, further comprising formulating a cathode sheet using the secondary particles; wherein the secondary particles have a d50 ranging from about 100 nm to about 1000 nm.

8. The method of claim 1, wherein the dry milled LMP powder has a d50 of less than or equal to 10 pm.

9. The method of claim 1, wherein the dry milled LMP powder has a d50 ranging from about 400 nm to about 800 nm.

10. The method of claim 1, wherein the secondary particles have a d50 ranging from about 100 nm to about 300 nm.

11. The method of claim 1 , wherein the liquid medium comprises an organic solvent selected from methanol, ethanol, isopropanol, 2-butanol, acetone, 2-butanone, and combinations thereof.

12. The method of claim 1, wherein the liquid medium is water.

13. The method of claim 1, wherein the wet-milled slurry is dried by a process of spray drying, air drying, or vacuum drying.

14. The method of claim 1, wherein the wet-milled slurry is spray dried with an inlet temperature of about 160 °C and an outlet temperature of about 105 °C.

15. The method of claim 1, wherein the calcining occurs at a temperature of about 700° C.

16. The method of claim 1, wherein the calcining occurs for about 1 hour.

17. The method of claim 1, wherein the ion source comprises one or more of LiiCCh, Li(OAc)«xH2O, lithium acetate hydrate, and LiOH.

18. The method of claim 1, wherein the ion source comprises one or more of Fe(ox)«2H2O, iron oxalate hydrate, Fe(Oac)2, and iron acetate.

19. The method of claim 1, wherein the ion source comprises one or more of Mn(Oac)2*4H2O, manganese oxalate hydrate; Mn(ox)*2H2O, manganese oxalate hydrate; and MnCCh.

20. The method of claim 1, wherein the ion source comprises one or more of H3PO4, (NH4)2HPO4, and (NH4)H2PO4.

21. The method of claim 1, wherein the calcining is performed using a controlled- atmosphere furnace, wherein traces of oxygen or byproducts are removed through a flow of inert gas in the furnace.

22. A method for producing stoichiometrically balanced olivine-type lithium-transition metal -phosphate (LMP) materials, the method comprising: dry milling particles of a non-stoichiometric olivine-type LMP material to obtain a dry milled LMP powder; adding an ion source to the dry milled LMP powder to form a mixture, wherein the ion source comprises one or more of lithium ions, transition metal ions, and phosphate ions; milling the LMP powder and ion source mixture with water to form a wet-milled slurry;spray drying the wet-milled slurry to yield primary particles comprising particles of the olivine-type LMP material, and the ion source; wherein the spray drying inlet temperature is about 160 °C and the spray drying outlet temperature is about 105 °C; wherein the primary particles have a d50 ranging from about 50 nm to about 5000 nm; and calcining the primary particles at a temperature of about 650° C about 800° C to produce secondary particles comprising LMP having a d50 ranging from about 50 nm to about 5000 nm; wherein the ratio of LMP in the secondary particles is stoichiometrically balanced for the lithium (L), transition metal (M), and phosphate (P).

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