Positive electrodes for rechargeable batteries

Abstract

Disclosed herein is a cathode material comprising: a structure comprising LiaMnxFeyDz(PO4)c, wherein the cathode material comprises at least two phases, wherein a first phase is an olivine phase, and a second phase, and wherein the olivine phase is present in an amount greater than 90 wt% based on the total weight of the at least two phases, wherein 1 ≤ a ≤ 1.2 wherein 0.4 ≤ x ≤ 0.8, wherein 0.2 ≤ y ≤ 0.6, wherein 1 ≤ c ≤ 1.1, wherein D comprises one or more cations different from Li+, Mn2+, and Fe2+, wherein D comprises at least Al3+ and Si4+, and wherein at least an amount of Al3+ and Si4+ is present in the second phase; wherein z is a total amount of moles of D present and is 0.01 ≤ z ≤ 0.1 wherein x + y + z = 1; and wherein the cathode material exhibits an electrode press density of greater than 2.2 g cm-3; and an electrode volumetric density equal to or greater than 1200 Wh L-1.

Description

Attorney Docket No.10046-611WO1 8386 MAN POSITIVE ELECTRODES FOR RECHARGEABLE BATTERIES CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application No.63 / 652,931 filed May 29, 2024, and U.S. Provisional Application No.63 / 637,648 filed April 23, 2024, the contents of which are incorporated herein by reference in their entirety. STATEMENT ACKNOWLEDGING GOVERNMENT SUPPORT

[0001] This invention was made with government support under Grant No. DE- SC0005397, awarded by the Department of Energy. The government has certain rights in the invention. TECHNICAL FIELD

[0002] This application relates generally to positive electrodes in rechargeable batteries. BACKGROUND

[0003] The projected exponential increase in electric vehicle (EV) production over the next decade will require a commensurate increase in the production of Li-ion batteries (LIB) that power them. To ensure the cost competitiveness of EVs, a significant reduction in the cost of LIBs (i.e., dollars per kWh) is needed, which demands both further improvement in energy density and a reduction in materials cost. LiNixMnyCozO2 (NMC) has been the dominant cathode chemistry in EV batteries due to its superior energy density, but its dependence on critical minerals – namely, nickel and cobalt – presents serious issues for cost, sustainability, and supply chain security. Due to recent advances in cell and pack design, LiFePO4 (LFP) has emerged as a leading cathode material for the sustainable production of low-cost LIBs. At approximately one third of the material cost of NMC due to the use of abundant and inexpensive iron and phosphorus, LFP can mitigate the economic and supply chain risks associated with NMC cathodes. LFP also has remarkable electrochemical and thermal stability, resulting in LIB cells with much better safety and lifetime than NMC. However, with a maximum practical capacity of 160 mA h g-1at an average discharge voltage of 3.4 V vs. Li / Li+, LFP offers muchAttorney Docket No.10046-611WO1 8386 MAN lower specific energy compared to NMC. Additionally, due to the lower bulk density of LFP along with the sub-micron particle size required to achieve full capacity, the packing density of LFP electrodes (e.g., < 2.5 g cm-3) is much lower than that of NMC (e.g., > 3.4 g cm-3), which further reduces practical energy density. To increase the energy density of LFP, Mn can be substituted for Fe in the olivine structure to form LiMnxFe1-xPO4 (LMFP). Since the Mn2+ / 3+redox in LMFP occurs at a higher voltage of 4.0 V vs. Li / Li+, the average operating voltage – and thus energy density – can theoretically be increased by 15% compared to LFP.

[0004] However, once the Mn content in LMFP surpasses 40%, kinetic limitations arise during Mn2+ / 3+redox, which can limit the accessible capacity and decrease the average discharge voltage. The root cause of these kinetic limitations is the Jann- Teller distortion caused by the high-spin 3d4electronic configuration of Mn3+, which results in an anisotropic lattice mismatch between the lithiated (Mn2+containing) and delithiated (Mn3+containing) phases and hinders the Li+diffusion kinetics along the phase boundary. For example, the apparent Li+diffusion coefficient calculated from the Atlung Method for Intercalant Diffusion was shown to be orders of magnitude higher during Fe2+ / 3+redox compared to Mn2+ / 3+redox for LMFP with 50% Mn content. These kinetic issues can be alleviated through various strategies, but each approach has detrimental effects on energy density. Inclusion of electrochemically inactive dopants, such as Mg or Ti, can mitigate the lattice strain and improve the Li+diffusion kinetics along both the phase boundary and particle surface, but with a penalty in theoretical specific capacity. Reducing the primary particle size of LMFP (i.e., to < 100 nm) lowers the Li+diffusion path length and dramatically improves the Mn2+ / 3+redox kinetics. However, excessively small particle size typically results in a low press density of the electrode, which reduces the cell-level energy density. For example, the tap density of LMFP powders is often < 1.0 g cm-3, which results in an electrode press density of < 2.0 g cm-3, while the tap density of LFP can be > 1.5 g cm-3, yielding a press density of > 2.5 g cm-3. As the Mn content in LMFP is increased past 60%, the kinetic limitations of Mn2+ / 3+redox become severe, requiring large amounts of inactive dopants (e.g., 5%) combined with very small primary particle sizes (e.g., 50 nm) to achieve full theoretical capacity. As a result, it is highly challenging for LMFP to achieve more than a 10% improvement in volumetric energy density compared to LFP.Attorney Docket No.10046-611WO1 8386 MAN

[0005] Thus, novel and suitable positive electrode materials with high volumetric energy density and more efficient methods of making the same are still needed. These needs and other needs are at least partially satisfied by the present disclosure. SUMMARY

[0006] In still further aspects, disclosed herein is a cathode material comprising: a structure comprising LiaMnxFeyDz(PO4)c, wherein the cathode material comprises at least two phases, wherein a first phase is an olivine phase, and a second phase, and wherein the olivine phase is present in an amount greater than 90 wt% based on the total weight of the at least two phases, wherein 1 ≤ a ≤ 1.2 wherein 0.4 ≤ x ≤ 0.8, wherein 0.2 ≤ y ≤ 0.6, wherein 1 ≤ c ≤ 1.1, wherein D comprises one or more cations different from Li+, Mn2+and Fe2+, wherein D comprises at least Al3+and Si4+, and wherein at least an amount of Al3+and Si4+is present in the second phase; wherein z is a total amount of moles of D present and is 0.01 ≤ z ≤ 0.1 wherein x + y + z = 1; and wherein the cathode material exhibits an electrode press density of greater than 2.2 g cm-3; and an electrode volumetric density of greater than 1200 Wh L-1.

[0007] In yet still further aspects, the LiaMnxFeyDz(PO4)c is formed from a precursor having a general formula Lia'Mnx'Fey'Mz'O4 and comprising one or more phases, wherein one or more phases is a spinel phase present in an amount of at least 95 wt% based on the total weight of all phases, wherein D comprises M, wherein 0.5 ≤ a' ≤ 1 wherein 0.8 ≤ x' ≤ 1.6, wherein 0.4 ≤ y' ≤ 1.2, wherein 0.01 <z' ≤ 0.2, and wherein a' + x' + y' + z' ≤ 3.

[0008] Also disclosed is a battery comprising any of the disclosed herein cathode materials. In still further aspects, the disclosed herein secondary batteries further comprise an anode electrode and an electrolyte.

[0009] In further aspects, disclosed herein is a method of making any of the disclosed herein cathode materials, wherein the cathode material is formed from (a) a mixture comprising: (i) a precursor having a general formula Lia'Mnx'Fey'Mz'O4 and comprising one or more phases, wherein one or more phases is a spinel phase present in an amount of at least 95 wt% based on the total weight of all phases; (ii) a phosphorous source; (iii) a lithium source; and (iv) a carbon source; (b) forming aAttorney Docket No.10046-611WO1 8386 MAN plurality of particles; and (c) heating the plurality of particles to form the structure comprising LiaMnxFeyDz(PO4)c.

[0010] Still further disclosed herein are methods of making any of the secondary batteries disclosed herein.

[0011] Additional advantages will be set forth in part in the description which follows, and in part will be obvious from the description or can be learned by practice of the aspects described below. The advantages described below will be realized and attained by means of the chemical compositions, methods, and combinations thereof, particularly pointed out in the appended claims. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed. BRIEF DESCRIPTION OF DRAWINGS

[0012] FIGURE 1 shows a schematic presenting the 2-step-carbon coating process for a Lithium-Manganese-Iron-Phosphate (LMFP) -based cathode electrode according to aspects of the disclosure.

[0013] FIGURE 2 shows a mixed solution of Fe0.5Mn0.5O, NH4H2PO4, and H2O. The high viscosity indicates that Mn2+dissolution has caused the forming of the byproducts that can affect the solution rheology.

[0014] FIGURES 3A-3E show an SEM image of LMFO spinel precursor (FIG.3A) with EDS mapping of Fe (FIG.3B) and Mn (FIG.3C). XRD patterns of LMFO (FIG. 3D) heated from 500 to 900oC and with adjusted Li amounts (FIG.3E), from 10% deficient Li to 10% excess Li based on molar ratios. JCPDS #04-008-1660, #00-035- 0782, #00-039-1346, and #00-027-1252 are used to identify the phases as, respectively, LMFO, LiMn2O4, Fe2O3, and Li2MnO3.

[0015] FIGURES 4A-4C show an SEM image (FIG.4A) of NH4Mn0.5Fe0.5PO4 with EDS mapping of Fe (FIG.4B) and Mn (FIG.4C).

[0016] FIGURE 5 shows XRD patterns of pristine LMFO and LMFO doped with 1 mol% Mg and 1 mol% Co.

[0017] FIGURES 6A-6D show XRD patterns (FIG.6A) of all three calcined LMFP samples synthesized with various precursors. JCPDS #04-013-7460 and #00-006-Attorney Docket No.10046-611WO1 8386 MAN 0696 are used to identify the phases of, respectively, LMFP and Fe. FIG.6B shows Nitrogen adsorption isotherms for S-LMFP and P-LMFP, with calculated surface area values presented. FIG.6C shows a TGA of carbon-coated LMFP samples with calculated carbon amounts presented based on subtraction from the theoretical decomposition mass of LMFP. FIG.6D shows an EIS of a symmetric cell with a blocking electrolyte.

[0018] FIGURES 7A-7I show SEM images of LMFP samples synthesized with (FIG. 7A, 7D, and 7G) LMFO, (FIG.7B, 7E, and 7H) NH4Fe0.5Mn0.5PO4, and (FIG.7C, 7F, and 7I) separate oxide precursors. Spray dried secondary particles (FIG.7A-7C) in their entirety and (FIG.7D-7F) zoomed into the surface of the secondary particle to investigate the primary particles. (FIG.7G-7I) FIB-SEM images of the cross-section of the secondary particles.

[0019] FIGURES 8A-8D show the electrochemical performances of S-LMFP and P- LMFP samples on a gravimetric basis. (FIG.8A) Half-cell cycling performance of LMFP samples over 100 cycles at C / 5 charge and discharge rate, (FIG.8B) discharge rate testing from C / 10 to 5C rate with a constant C / 10 charge rate, and the voltage profiles presented at various discharge rates for (FIG.8C) S-LMFP and (FIG. 8D) P-LMFP. Aerial capacities are indicated, and press densities for S-LMFP and P- LMFP are, respectively, 2.31 and 1.93 g cm-3.

[0020] FIGURES 9A-9B show the electrochemical performances of all three LMFP samples on a gravimetric basis. (FIG.9A) Half-cell cycling performance of three LMFP samples and (FIG.9B) voltage profiles presented for C / 5 charge and discharge rate. Aerial capacities for all the samples with 1.4 to 1.6 mA h cm-2. The press densities of S-LMFP, P-LMFP, and O-LMFP are, respectively, 2.31, 1.93, and 2.40 g cm-3.

[0021] FIGURES 10A-10F show discharge rate testing of (FIG.10A) S-LMFP and (FIG.10D) P-LMFP up to 10C rate when compressed to varying press densities with a C / 10 charge rate. (FIG.10B) Volumetric capacity, (FIG.10C) average discharge potential, and (FIG.10E) volumetric energy on a cathode level of all S-LMFP and P- LMFP samples tested. (FIG.10F) Volumetric energy is examined as a function of press density with the P-LMFP projected values until the critical press density is reached.Attorney Docket No.10046-611WO1 8386 MAN

[0022] FIGURES 11A-11D show the electrochemical performances of S-LMFP (FIGs.11A and 11C) and P-LMFP (FIGs.11B and 11D) at varying temperatures during cycling. (FIGs.11A and 11B) Discharge voltage profiles and (FIGs.11C and 11D) dQ / dV plots at C / 5 rate.

[0023] FIGURE 12 shows a TGA of three S-LMFP samples containing three different amounts of carbon coatings, indicated by the difference between the theoretical decomposition mass gain and the final mass of each sample analyzed.

[0024] The accompanying figures, which are incorporated in and constitute a part of this specification, illustrate several aspects described below. DETAILED DESCRIPTION

[0025] The present invention can be understood more readily by reference to the following detailed description, examples, drawings, and claims, and their previous and following description. However, before the present articles, systems, and / or methods are disclosed and described, it is to be understood that this invention is not limited to the specific or exemplary aspects of articles, systems, and / or methods disclosed unless otherwise specified, as such can, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular aspects only and is not intended to be limiting.

[0026] The following description of the invention is provided as an enabling teaching of the invention in its best, currently known aspect. To this end, those skilled in the relevant art will recognize and appreciate that many changes can be made to the various aspects of the invention described herein while still obtaining the beneficial results of the present invention. It will also be apparent that some of the desired benefits of the present invention can be obtained by selecting some of the features of the present invention without utilizing other features. Accordingly, those of ordinary skill in the pertinent art will recognize that many modifications and adaptations to the present invention are possible and may even be desirable in certain circumstances and are a part of the present invention. Thus, the following description is again provided as illustrative of the principles of the present invention and not in limitation thereof.Attorney Docket No.10046-611WO1 8386 MAN DEFINITIONS

[0027] As used herein, the terms "optional" or "optionally" mean that the subsequently described event or circumstance can or cannot occur and that the description includes instances where said event or circumstance occurs and instances where it does not.

[0028] It is appreciated that certain features of the disclosure, which are, for clarity, described in the context of separate aspects, can also be provided in combination in a single aspect. Conversely, various features of the disclosure, which are, for brevity, described in the context of a single aspect, can also be provided separately or in any suitable subcombination.

[0029] As used in the description and the appended claims, the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, a reference to “a salt” includes two or more such salts, and a reference to “a battery” includes two or more such batteries and the like.

[0030] It is also to be understood that the terminology used herein is for the purpose of describing particular aspects only and is not intended to be limiting. As used in the specification and in the claims, the term “comprising” can include the aspects “consisting of” and “consisting essentially of.” 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 invention belongs. In this specification and in the claims which follow, reference will be made to a number of terms that shall be defined herein.

[0031] For the terms "for example" and "such as," and grammatical equivalences thereof, the phrase "and without limitation" is understood to follow unless explicitly stated otherwise. It is further understood that these phrases are used for explanatory purposes only. It is further understood that the term “exemplary,” as used herein, means “an example of” and is not intended to convey an indication of a preferred or ideal aspect.

[0032] The expressions "ambient temperature" and "room temperature" as used herein are understood in the art and refer generally to a temperature from 20 °C to 35 °C.Attorney Docket No.10046-611WO1 8386 MAN

[0033] Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the disclosure are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors, necessarily resulting from the standard deviation found in their respective testing measurements. Furthermore, when numerical ranges of varying scope are set forth herein, it is contemplated that any combination of these values, inclusive of the recited values, may be used. Further, ranges can be expressed herein as from “about” one particular value and / or to “about” another particular value. When such a range is expressed, another aspect includes from the one particular value and / or to the other particular value.

[0034] Similarly, when values are expressed as approximations, by use of the antecedent “about,” it will be understood that the particular value forms another aspect. It will be further understood that the endpoints of each of the ranges are significant both in relation to the other endpoint and independently of the other endpoint. Unless stated otherwise, the term “about” means within 5% (e.g., within 2% or 1%) of the particular value modified by the term “about.”

[0035] All disclosed values also include values that fall within ±10% variation from the disclosed value unless otherwise indicated or inferred. In other words, if a range of 1 to 10 is disclosed, then a range of about 1 to about 10 is disclosed. In such aspects, it is understood that the amount or value in question can be the exact value or a value that provides equivalent results or effects as recited in the claims or taught herein. That is, amounts, sizes, formulations, parameters, and other quantities and characteristics include both exact values but also approximate, larger or smaller values as desired, reflecting tolerances, conversion factors, rounding, measurement error, and the like, and other factors known to those of skill in the art such that equivalent results or effects are obtained. In some circumstances, the value that provides equivalent results or effects cannot be reasonably determined. In general, an amount, size, formulation, parameter, or other quantity or characteristic is "about," "approximate," or "at or about," whether or not expressly stated to be such. Where "about," "approximate," or "at or about" is used before a quantitative value, the parameter also includes the specific quantitative value itself unless expressly stated otherwise.Attorney Docket No.10046-611WO1 8386 MAN

[0036] As used herein, the term or phrase “effective,” “effective amount,” or “conditions effective to” refers to such amount or condition that is capable of performing the function or property for which an effective amount or condition is expressed. As will be pointed out below, the exact amount or particular condition required will vary from one aspect to another, depending on recognized variables such as the materials employed and the processing conditions observed. Thus, it is not always possible to specify an exact “effective amount” or “condition effective to.” However, it should be understood that an appropriate, effective amount will be readily determined by one of ordinary skill in the art.

[0037] When a range is expressed, a further aspect includes from the one particular value and to the other particular value. For example, where the stated range includes one or both of the limits, ranges excluding either or both of those included limits are also included in the disclosure, e.g., the phrase "x to y" includes the range from 'x' to 'y' as well as the range greater than 'x' and less than 'y'. The range can also be expressed as an upper limit, e.g., 'x, y, z, or less' and should be interpreted to include the specific ranges of ‘x,’ ‘y,’ ‘z,’ 'about x,' 'about y,' and 'about z' as well as the ranges of 'less than x,' 'less than y, or 'less than z,' or 'less than about x,' 'less than about y, and 'less than about z.' Likewise, the phrase ' x, y, z, or greater' should be interpreted to include the specific ranges of ‘x,’ ‘y,’ ‘z,’ 'about x,' 'about y,' and 'about z' as well as the ranges of 'greater than x,' greater than y,' 'greater than z,' or 'greater than about x,' greater than about y,' 'greater than about z.' In addition, the phrase " 'x' to 'y'," where 'x' and 'y' are numerical values, also includes "about 'x' to about 'y'."

[0038] Such a range format is used for convenience and brevity and, thus, should be interpreted flexibly to include not only the numerical values explicitly recited as the limits of the range but also to include all the individual numerical values or sub- ranges encompassed within that range as if each numerical value and sub-range is explicitly recited. To illustrate, a numerical range of " 0.1% to 5%" should be interpreted to include not only the explicitly recited values of 0.1% to 5% but also include individual values (e.g., 1%, 2%, 3%, and 4%) and the sub-ranges (e.g., 0.5% to 1.1%; 5% to 2.4%; 0.5% to 3.2%, and 0.5% to 4.4%, and other possible sub- ranges) within the indicated range.Attorney Docket No.10046-611WO1 8386 MAN

[0039] Throughout this disclosure, various aspects of the invention can be presented in a range format. It should be understood that the description in range format is merely for convenience and brevity and should not be construed as an inflexible limitation on the scope of the invention. Accordingly, the description of a range should be considered to have specifically disclosed all the possible subranges as well as individual numerical values within that range. For example, a description of a range such as from 1 to 6 should be considered to have specifically disclosed subranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as individual numbers within that range, for example, 1, 2, 2.7, 3, 4, 5, 5.3, 6 and any whole and partial increments therebetween. This applies regardless of the breadth of the range.

[0040] In still further aspects, when the specific values are disclosed between two end values, it is understood that these end values can also be included.

[0041] In still further aspects, when the range is given, and exemplary values are provided, it is understood that any ranges can be formed between any exemplary values within the broadest range. For example, if individual numbers 1, 2, 3, 4, 5, 6, 7, etc. are disclosed, then the ranges 1-7, 2-7, 3-7, 4-7, 5-7, 6-7, 1-6, 1-5, 1-4, 1-3, 1- 2, 2-6, 2-5, etc. are also disclosed.

[0042] References in the specification and concluding claims to parts by weight of a particular element or component in a composition denote the weight relationship between the element or component and any other elements or components in the composition or article for which a part by weight is expressed. Thus, in a mixture containing 2 parts by weight of component X and 5 parts by weight, components Y, X, and Y are present at a weight ratio of 2:5 and are present in such a ratio regardless of whether additional components are contained in the mixture.

[0043] A weight percent (wt.%) of a component, unless specifically stated to the contrary, is based on the total weight of the formulation or composition in which the component is included.

[0044] It will be understood that when an element is referred to as being "connected" or "coupled" to another element, it can be directly connected or coupled to the other element, or intervening elements may be present. In contrast, when an element is referred to as being "directly connected" or "directly coupled" to another element,Attorney Docket No.10046-611WO1 8386 MAN there are no intervening elements present. Other words used to describe the relationship between elements or layers should be interpreted in a like fashion (e.g., "between" versus "directly between," "adjacent" versus "directly adjacent," "on" versus "directly on").

[0045] As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0046] It will be understood that the terms "first," "second," etc., may be used herein to describe various elements, components, regions, layers, and / or sections. These elements, components, regions, layers, and / or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer, or section from another element, component, region, layer, or section. Thus, a first element, component, region, layer, or section discussed below could be termed a second element, component, region, layer, or section without departing from the teachings of example embodiments.

[0047] As used herein, the term "substantially" means that the subsequently described event or circumstance completely occurs or that the subsequently described event or circumstance generally, typically, or approximately occurs.

[0048] Still further, the term “substantially” can, in some aspects, refer to at least about 80 %, at least about 85 %, at least about 90 %, at least about 91 %, at least about 92 %, at least about 93 %, at least about 94 %, at least about 95 %, at least about 96 %, at least about 97 %, at least about 98 %, at least about 99 %, or about 100 % of the stated property, component, composition, or other condition for which substantially is used to characterize or otherwise quantify an amount.

[0049] In other aspects, as used herein, the term “substantially free,” when used in the context of a composition or component of a composition that is substantially absent, is intended to refer to an amount that is then about 1 % by weight, e.g., less than about 0.5 % by weight, less than about 0.1 % by weight, less than about 0.05 % by weight, or less than about 0.01 % by weight of the stated material, based on the total weight of the composition.

[0050] As used herein, the terms “substantially identical reference composition,” “substantially identical reference article,” or “substantially identical referenceAttorney Docket No.10046-611WO1 8386 MAN electrochemical cell” refer to a reference composition, article, or electrochemical cell comprising substantially identical components in the absence of an inventive component. In another exemplary aspect, the term "substantially," in, for example, the context "substantially identical reference composition," or “substantially identical reference article,” or “substantially identical reference electrochemical cell,” refers to a reference composition, article, or an electrochemical cell comprising substantially identical components and wherein an inventive component is substituted with a common in the art component.

[0051] While aspects of the present invention can be described and claimed in a particular statutory class, such as the system statutory class, this is for convenience only and one of ordinary skill in the art will understand that each aspect of the present invention can be described and claimed in any statutory class. Unless otherwise expressly stated, it is in no way intended that any method or aspect set forth herein be construed as requiring that its steps be performed in a specific order. Accordingly, where a method claim does not specifically state in the claims or descriptions that the steps are to be limited to a specific order, it is in no way intended that an order be inferred in any respect. This holds for any possible non- express basis for interpretation, including matters of logic with respect to the arrangement of steps or operational flow, plain meaning derived from grammatical organization or punctuation, or the number or type of aspects described in the specification.

[0052] The present invention may be understood more readily by reference to the following detailed description of various aspects of the invention and the examples included therein and to the Figures and their previous and following description. CATHODE MATERIALS

[0053] In certain aspects, disclosed herein are novel cathode electrode materials.

[0054] In certain aspects, disclosed herein is a cathode material comprising: a structure comprising LiaMnxFeyDz(PO4)c, wherein the cathode material comprises at least two phases. In such aspects, the cathode material comprises a first phase and a second phase. In such exemplary and unlimiting aspects, the first phase is an olivine phase that is present in an amount greater than 90 wt%, greater than 91 wt%, greater than 92 wt%, greater than 93 wt%, greater than 94 wt%, greater than 95Attorney Docket No.10046-611WO1 8386 MAN wt%, greater than 96 wt%, greater than 97 wt%, greater than 98 wt%, or greater than 99 wt% based on the total weight of the at least two phases. Yet in other aspects, the olivine phase that is present in an amount of greater than 90 wt% to less than 100 wt% based on the total weight of the at least two phase, including exemplary ranges of 90.5 wt% to less than 100 wt%, 91 wt% to less than 100 wt%, 93 wt% to less than 100 wt%, 95 wt% to less than 100 wt%, 98 wt% to less than 100 wt%, 90.5 wt% to 99.5 wt%, 90.5 wt% to 99 wt%, 90.5 wt% to 98 wt%,90.5 wt% to 97 wt%,90.5 wt% to 96 wt%, 90.5 wt% to 95 wt%, 90.5 wt% to 94 wt%, 90.5 wt% to 93 wt%, and so on.

[0055] In still further aspects, 1≤ a ≤ 1.2, including exemplary values of 1, 1.01, 1.05, 1.07, 1.1, 1.12, 1.15, 1.17, and 1.20. It is understood that a can have any value between any two foregoing values, or it can fall within any range formed by any two disclosed values. In some aspects, a can be 1.01-1.2, 1.02-1.2, 1.05-1.2, 1.07-1.2, 1.1-1.2, 1.12-1.2, 1.15-1.2, 1.7-1.2, 1.00-1.17, 1.00-1.15, 1.00-1.12, 1-1.1, 1-1.07, 1- 1.05, 1.02-1.1, and so on.

[0056] In still further aspects, 0.4 ≤ x ≤ 0.8, including exemplary values of 0.4, 0.45. 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, and 0.8. It is understood that x can have any value between any two foregoing values, or it can fall within any range formed by any two disclosed values. In some aspects, x can be 0.4-0.75, 0.4-0.7, 0.4-0.65, 0.4-0.6, 0.4- 0.55, 0.4-0.5, 0.4-0.55, 0.4-0.5, 0.45-0.8, 0.5-0.8, 0.55-0.8, 0.6-0.8, 0.65-0.8, and so on.

[0057] In still further aspects, 0.2 ≤ y ≤ 0.6, including exemplary values of 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, and 0.6. It is understood that y can have any value between any two foregoing values, or it can fall within any range formed by any two disclosed values. In some aspects, y can be 0.2-0.55, 0.2-0.5, 0.2-0.45, 0.2-0.4, 0.2- 0.35, 0.2-0.3, 0.25-0.6, 0.3-0.6, 0.35-0.6, 0.4-0.6, 0.45-0.6, 0.5-0.6, and so on.

[0058] In still further aspects, 1 ≤ c ≤ 1.1, including exemplary values of 1.01, 1.02, 1.03, 1.04, 1.05, 1.06, 1.07, 1.08, 1.09, and 1.1. It is understood that c can have any value between any two foregoing values, or it can fall within any range formed by any two disclosed values. In some aspects, c can be 1.01-1.1, 1.02-1.1, 1.03-1.1, 1.04-1.1, 1.05-1.1, 1.05-1.1, 1.07-1.1, 1-1.09, 1-1.08, 1-1.07, 1-1.06, 1-1.05, 1.01- 1.05, and so on.Attorney Docket No.10046-611WO1 8386 MAN

[0059] In still further aspects, 0.01 ≤ z ≤ 0.1, including exemplary values of 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, and 0.1. It is understood that z can have any value between any two foregoing values, or it can fall within any range formed by any two disclosed values. In some aspects, z can be 0.01-0.1, 0.02-0.1, 0.03-0.1, 0.04-0.1, 0.05-0.1, 0.05-0.1, 0.07-0.1, 0.01-0.09, 0.01-0.08, 0.01-0.07, 0.01-0.06, 0.01-0.05, 0.02-0.06, and so on.

[0060] In still further aspects, D comprises one or more cations. Yet in still further aspects, D comprises two or more cations. In such exemplary and unlimiting aspects, the one or more cations present in D are different from Li+, Mn2+,and Fe2+. In still further aspects, D comprises at least Al3+and Si4+. In such exemplary and unlimiting aspects, at least an amount of Al3+and Si4+is present in the second phase. It is further understood that in some aspects, at least some amount of Al3+and / or Si4+can also be present in the first phase. In still further aspects, D can further comprise Ni2+, Co2+, Zn2+, Mg2+, Cu2+, B3+, V3+, Cr3+, Ti4+, Zr4+, Nb5+, Ta5+, Mo6+, W6+, or a combination thereof. It is understood that any of the above-mentioned elements can be present in either the first phase, the second phase, or any combination thereof.

[0061] In still further aspects, the disclosed above z is the total amount of moles of D present.

[0062] In still further aspects, x + y + z = 1.

[0063] In still further aspects, the cathode material described herein exhibits an electrode press density of greater than 2.2 g cm-3, greater than 2.3 g cm-3, greater than 2.4 g cm-3, greater than 2.5 g cm-3, greater than 2.6 g cm-3, greater than 2.7 g cm-3, or greater than 2.8 g cm-3. In still further aspects, the electrode press density is greater than or equal to 2.2 g cm-3to 2.8 g cm-3, greater than or equal to 2.3 g cm-3to 2.8 g cm-3, greater than or equal to 2.4 g cm-3to 2.8 g cm-3, greater than or equal to 2.5 g cm-3to 2.8 g cm-3, or greater than or equal to 2.4 g cm-3to 2.7 g cm-3, greater than or equal to 2.4 g cm-3to 2.6 g cm-3and so on. Yet in still further aspects, the electrode press density is at least 2.4 g / cm3to above 2.6 g / cm3.

[0064] In still further aspects, the cathode material described herein exhibits an electrode tap density of greater than 1.2 g cm-3,greater than 1.3 g cm-3, greater than 1.4 g cm-3, greater than 1.5 g cm-3, greater than 1.6 g cm-3, greater than 1.7 g cm-3,Attorney Docket No.10046-611WO1 8386 MAN or greater than 1.8 g cm-3. In still further aspects, the electrode press density is greater than 1.2 g cm-3to 1.8 g cm-3, greater than or equal to 1.3 g cm-3to 1.8 g cm-3, greater than or equal to 1.4 g cm-3to 1.8 g cm-3, greater than or equal to 1.5 g cm-3to 1.8 g cm-3, or greater than or equal to 1.4 g cm-3to 1.7 g cm-3, greater than or equal to 1.4 g cm-3to 1.6 g cm-3and so on.

[0065] In still further aspects, the cathode material disclosed herein exhibits an electrode volumetric density equal to or greater than 1100 Wh L-1, equal to or greater than 1110 Wh L-1, equal to or greater than 1120 Wh L-1, equal to or greater than 1130 Wh L-1, equal to or greater than 1140 Wh L-1, equal to or greater than 1150 Wh L-1, equal to or greater than 1160 Wh L-1, equal to or greater than 1170 Wh L-1, equal to or greater than 1180 Wh L-1, equal to or greater than 1190 Wh L-1, equal to or greater than 1200 Wh L-1, equal to or greater than 1210 Wh L-1, equal to or greater than 1220 Wh L-1, equal to or greater than 1230 Wh L-1, equal to or greater than 1240 Wh L-1, equal to or greater than 1250 Wh L-1, equal to or greater than 1300 Wh L-1, equal to or greater than 1350 Wh L-1, or equal to or greater than 1400 Wh L-1. In some aspects, the cathode material disclosed herein exhibits an electrode volumetric density from 1200-1450 Wh L-1, from 1250-1450 Wh L-1, from 1300-1450 Wh L-1, from 1350-1450 Wh L-1, from 1400-1450 Wh L-1, from 1200-1400 Wh L-1, from 1250- 1400 Wh L-1, from 1300-1400 Wh L-1, from 1250-1350 Wh L-1, or from 1200-1300 Wh L-1.

[0066] In still further aspects, the cathode material disclosed herein exhibits a specific capacity of 100 mAh g-1to 400 mAh g-1at a discharge rate of at least 0.1C. For example, the cathode material can exhibit a specific capacity of 100 mAh g-1to 400 mAh g-1, including exemplary values of 110 mAh g-1, 120 mAh g-1, 145 mAh g-1, 150 mAh g-1, 200 mAh g-1, 250 mAh g-1, 300 mAh g-1, and 350 mAh g-1, at a discharge rate of at least 0.1C, of at least 0.2C, of at least 0.5C, of at least 1C, of at least 2C, of at least 3C, of at least 4C, of at least 5C, and so on. It is understood that the specific capacity can fall between any disclosed above values or can fall within any range formed by the disclosed above values. In certain aspects, the cathode material disclosed herein exhibit a specific capacity of 100 mAh g-1to 400 mAh g-1, 145 mAh g-1to 400 mAh g-1, 200 mAh g-1to 400 mAh g-1, 300 mAh g-1to 400 mAh g-1, 100 mAh g-1to 350 mAh g-1, 100 mAh g-1to 300 mAh g-1, 100 mAh g-1to 250 mAhAttorney Docket No.10046-611WO1 8386 MAN g-1, 100 mAh g-1to 200 mAh g-1, 110 mAh g-1to 190 mAh g-1, 120 mAh g-1to 180 mAh g-1, 130 mAh g-1to 170 mAh g-1, 140 mAh g-1to 160 mAh g-1, and so on at any of the disclosed above discharge rates.

[0067] In still further aspects, the second phase can comprise lithium, phosphorous, and oxygen. In certain aspects, the second phase can be lithium-rich. In other aspects, the second phase can be phosphorous-rich and oxygen-rich. In still further aspects, the second phase can be lithium-rich, phosphorus-rich, and oxygen-rich.

[0068] In still further aspects, the cathode material with the structure of LiaMnxFeyDz(PO4)c, as disclosed herein, can be formed by any known in the art methods as disclosed in detail below. Yet, in some aspects, the cathode material with the structure of LiaMnxFeyDz(PO4)c is formed from a precursor having a general formula Lia'Mnx'Fey'Mz'O4. In such aspects, the precursor can comprise one or more phases. In certain aspects, the one or more phases is a spinel phase present in an amount of at least 95 wt% based on the total weight of all phases or at least 96 wt%, at least 97 wt%, at least 98 wt%, or at least 99 wt% based on the total weight of all phases. Yet in other aspects, the spinel phase that is present in an amount of at least 95 wt% to less than or equal to 100 wt% based on the total weight of all phases, including exemplary ranges of 95.5 wt% to less than or equal to 100 wt%, 96 wt% to less than or equal to 100 wt%, 97 wt% to less than or equal to 100 wt%, 98 wt% to less than or equal to 100 wt%, 99 wt% to less than or equal to 100 wt%, 95.5 wt% to 99.9 wt%, 95 wt% to 99 wt%, 95 wt% to 98 wt%,95 wt% to 97 wt%,95 wt% to 96 wt%, and so on.

[0069] In still further aspects, D in the structure of LiaMnxFeyDz(PO4)c comprises M.

[0070] In still further aspects, 0.5 ≤ a' ≤ 1, including exemplary values of 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95, and 1. It is understood that a’ can have any value between any two foregoing values, or it can fall within any range formed by any two disclosed values. In some aspects, a’ can be 0.6-1, 0.65-1, 0.7-1, 0.75-1, 0.8-1, 0.85-1, 0.9-1, 0.95-1, 0.5-0.95, 0.5-0.9, 0.5-0.85, 0.5-0.8, 0.5-0.75, 0.5-0.7, 0.5-0.75, 0.5-0.6, and so on.

[0071] In still further aspects, 0.8 ≤ x' ≤ 1.6, including exemplary values of 0.8, 0.85, 0.9, 0.95.1, 1.05, 1.1, 1.15, 1.2, 1.25, 1.3, 1.35, 1.4, 1.45, 1.5, 1.55, and 1.6. It is understood that x’ can have any value between any two foregoing values, or it canAttorney Docket No.10046-611WO1 8386 MAN fall within any range formed by any two disclosed values. In some aspects, x’ can be 0.8-1.55, 0.8-1.5, 0.8-1.45, 0.8-1.4, 0.8-1.35, 0.8-1.3, 0.8-1.35, 0.8-1.3, 0.8-1.25, 0.8- 1.2, 0.8-1.15, 0.8-1.1, 0.8-1.05, 0.8-1, 0.8-0.95, 0.8-0.9, 0.85-1.6, 0.9-1.6, 0.95-1.6, 1-1.6, 1.05-1.6, 1.1-1.6, 1.15-1.6, 1.2-1.6, 1.25-1.6, 1.3-1.6, 1.35-1.6, 1.4-1.6, 1.45- 1.6, and so on.

[0072] In still further aspects, 0.4 ≤ y' ≤ 1.2, including exemplary values of 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95, 1, 1.05, 1.1, 1.15, and 0.2. It is understood that y’ can have any value between any two foregoing values, or it can fall within any range formed by any two disclosed values. In some aspects, y’ can be 0.4-1.15, 0.4-1.1, 0.4-1.05, 0.4-1, 0.4-0.95, 0.4-0.9, 0.4-0.85, 0.4-0.8, 0.4-0.75, 0.4- 0.7, 0.4-0.65, 0.4-0.6, 0.4-0.55, 0.45-1.2, 0.5-1.2, 0.55-1.2, 0.6-1.2, 0.65-1.2, 0.7-1.2, 0.75-1.2, 0.8-1.2, 0.55-1.2, 0.9-1.2, 0.95-1.2, 1-1.2, 1.05-1.2, 1.1-1.2, and so on.

[0073] In still further aspects, 0.01 <z' ≤ 0.2, including exemplary values of 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.11, 0.12, 0.13, 0.14, 0.15, 0.16, 0.17, 0.18, 0.19, and 0.2. It is understood that z’ can have any value between any two foregoing values, or it can fall within any range formed by any two disclosed values. In some aspects, z’ can be 0.02-0.2, 0.03-0.2, 0.04-0.2, 0.05-0.2, 0.06-0.2, 0.07-0.2, 0.08-0.2, 0.09-0.2, 0.1-0.2, 0.11-0.2, 0.12-0.2, 0.13-0.2, 0.14-0.2, 0.15-0.2, 0.16-0.2, 0.17-0.2, 0.18-0.2, 0.01-0.19, 0.01-0.18, 0.01-0.17, 0.01-0.16, 0.01-0.15, 0.01-0.14, 0.01-0.13, 0.01-0.12, 0.01-0.11, 0.01-0.1, 0.01-0.09, 0.01-0.08, 0.01-0.07, 0.01-0.06, 0.01-0.05, 0.01-0.04, 0.01-0.03, and so on.

[0074] In still further aspects, a' + x' + y' + z' ≤ 3. For example, the sum can be 3, can be 2.5, can be 2, and any numbers that fall in between, and so on.

[0075] In certain aspects, M comprise one or more cations. In still further aspects, M comprises two or more cations. In still further aspects, M comprises at least Al3+and Si4+. Yet in other aspects, M further comprises Mg2+, Zn2+, Ni2+, Cu2+, B3+, Co3+, V3+, Cr3+, V4+, Ti4+, P5+, V5+, or a combination thereof.

[0076] In certain aspects, the D in the disclosed herein cathode material can further comprise Na+, K+, Ca2+, Ba2+, and Sr2+. In such aspects, these cations can be present in an amount of less than 25 mole%, less than 10 mole%, less than 5 mole%, less than 3 mole %, or less than 1 mole % of the total ions present in D. In still further aspects, M can comprise Na+, K+, Ca2+, Ba2+, and Sr2+. In such aspects,Attorney Docket No.10046-611WO1 8386 MAN these cations can be present in an amount of less than 25 mole%, less than 10 mole%, less than 5 mole%, less than 3 mole %, or less than 1 mole % of the total ions present in M.

[0077] In still further aspects, the LiaMnxFeyDz(PO4)c can comprise a plurality of primary particles having an average size of 50 to 500 nm, including exemplary values of 75 nm, 100 nm, 125 nm, 150 nm, 175 nm, 200 nm, 225 nm, 250 nm, 275 nm, 300 nm, 325 nm, 350 nm, 375 nm, 400 nm, 425 nm, 450 nm, and 475 nm. In still further aspects, the primary particles can have any size that falls between any two foregoing values of can fall within a range formed by any of the two foregoing values. In certain aspects, and without limitations, the primary particles can have an average size of 50-475 nm, 50-450 nm, 50-425 nm, 50-400 nm, 50-375 nm, 50-350 nm, 50- 325 nm, 50-300 nm, 50-275 nm, 50-250 nm, 50-225 nm, 50-200 nm, 50-175 nm, 50- 150 nm, 50-125 nm, 50-100 nm, 50-75 nm, 75-500 nm, 100-500 nm, 150-500 nm, 175-500 nm, 200-500 nm, 250-500 nm, 275-500 nm, 300-500 nm, 350-500 nm, 375- 500 nm, 400-500 nm, 450-500 nm, 50-400 nm, 75-350 nm, 100-300 nm, and so on.

[0078] In still further aspects, the cathode material disclosed herein comprises an amount of carbon. In such exemplary and unlimiting aspects, the amount of carbon is at least 1 wt% and up to 5 wt% based on the total weight of the cathode material, including exemplary values of 1.2 wt%, 1.5 wt%, 1.7 wt%, 2 wt%, 2.2 wt%, 2.5 wt%, 2.7 wt%, 3 wt%, 3.2 wt%, 3.5 wt%, 3.7 wt%, 4 wt%, 4.2 wt%, 4.5 wt%, and 4.7 wt%. In still further aspects, the carbon can be present in any amount that falls between any two foregoing values, or it can fall within a range formed by any of the two foregoing values. In certain aspects, and without limitations, carbon can be present in an amount of 1 wt% to 4.5 wt, 1 wt% to 4 wt%, 1 wt% to 3.5 wt%, 1 wt% to 3 wt%, 1 wt% to 2.5 wt, 1 wt% to 2 wt%, 1.5 wt% to 5 wt%, 2 wt% to 5 wt%, 2.5 wt% to 5 wt%, 3 wt% to 5 wt%, 3.5 wt % to 5 wt%, 3 wt% to 5 wt%, 1.5 wt% to 3 wt%, and so on.

[0079] In still further aspects, the carbon is disposed as a coating on the primary particles, wherein the coating has a thickness of less than 10 nm, less than 9.5 nm, less than 9 nm, less than 8.5 nm, less than 8 nm, less than 7.5 nm, less than 7 nm, less than 6.5 nm, less than 6 nm, less than 5.5 nm, less than 5 nm, less than 4.5 nm, less than nm, less than 3.5 nm, less than 3 nm, less than 2.5 nm, less than 2 nm,Attorney Docket No.10046-611WO1 8386 MAN less than 1.5 nm, or less than 1 nm. In still further aspects, the coating has a thickness of 1 nm to 10 nm, including exemplary values of 2, 3, 4, 5, 6, 7, 8, and 9 nm. In still further aspects, the coating can have any thickness value that falls between any two foregoing values, or it can fall within a range formed by any of the two foregoing values. In certain aspects, and without limitations, the coating can have a thickness of 1 nm to 8 nm, 1 nm to 7 nm, 1 nm to 5 nm, and so on.

[0080] In still further aspects, the plurality of primary particles form agglomerates having a substantially spherical shape and an average diameter of 1- 25 microns, including exemplary values of 2.5 microns, 5 microns, 7.5 microns, 10 microns, 12.5 microns, 15 microns, 17.5 microns, 20 microns, and 22.5 microns. In still further aspects, the aggregates can have any average size that falls between any two foregoing values, or it can fall within a range formed by any of the two foregoing values. In certain aspects, and without limitations, the aggregates can have any average size of 1.5-25 microns, 2-25 microns, 5-25 microns, 10-25 microns, 15-25 microns, 20-25 microns, 1-20 microns, 1-15 microns, 1-10 microns, 1-5 microns, and so on.

[0081] In still further aspects, the Mn and Fe are uniformly distributed within the olivine phase of LiaMnxFeyDz(PO4)c. BATTERIES

[0082] Disclosed herein are secondary batteries that comprise any of the disclosed above cathode electrodes without limitations.

[0083] In still further aspects, the battery further comprises an anode electrode and an electrolyte.

[0084] In still further aspects, any known in the art anode materials can be present. For example, and without limitations, the anode electrode comprises one or more metallic alkali and / or alkaline earth foils, alkali and / or alkaline earth powder, alkali and / or alkaline earth meshes, alkali and / or alkaline earth alloys, carbon materials, non-alkali and / or non-alkaline earth metal alloys, nonmetal alloys, compound materials, or any combination thereof. Yet in still further aspects, the anode electrode comprises Li metal, Li metal alloy, lithium titanium oxide, titanium niobium oxide, silicon alloy, silicon tin alloy, tin, aluminum, carbon, graphite, carbonaceous anodes,Attorney Docket No.10046-611WO1 8386 MAN or any combination thereof. In still further aspects, any known in the art anode materials can be used. Yet in still further aspects, the battery can be “anodeless.” In such aspects, the anode electrode is a current collector for an alkali metal or alkaline earth metal deposition during a plating step. In such aspects, the current collectors can be a metal or another conductive material, such as (but not limited to) nickel (Ni), copper (Cu), aluminum (Al), iron (Fe), stainless steel, or conductive carbon materials. The current collector may be a foil, a foam, or a polymer substrate coated with a conductive material.

[0085] In still further aspects, the electrolyte is a liquid electrolyte comprising a salt and a solvent. In such aspects, the salt can comprise one or more of lithium fluorophosphate (LiPF6), lithium fluoroborate (LiBF4), lithium tetraphenylborate (LiBPh4), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium (fluorosulfonyl)(trifluoromethanesulfonyl)imide (LiFTFSI), lithium perchlorate (LiClO4), lithium nitrate (LiNO3), lithium 4,5-dicyano-2-(trifluoromethyl)imidazole (LiTDI), lithium 4,5-dicyano-2-(pentafluoromethyl)imidazole (LiPDI), and lithium difluorooxalato borate (LiDFOB), or any combination thereof.

[0086] In yet further aspects, the solvent comprises one or more of ethylene carbonate (EC), 1,2-dimethoxyethane (DME), propylene carbonate (PC), dimethyl carbonate (DMC), diethyl carbonate (DEC), 1,2-dimethoxyethane (DME), fluoroethylene carbonate (FEC), tetrahydrofuran (THF), diethylene glycol dimethyl ether (diglyme), triethylene glycol dimethyl ether (TDEM), tetraethylene glycol dimethyl ether (TEGDME), and vinylene carbonate (VC), bis(2,2,2-trifluoroethyl) ether (BTFE), 1,1,2,2-tetrafluoroethyl 2,2,3,3-tetrafluoropropylether (TTE), tris(2,2,2- trilfuoroethyl) orthoformate (TFEO), trimethylphosphate (TMP), triethylphosphate (TEP), methyl acetate, propionate, butyrate, or any combination hereof. It is understood that the electrolyte can comprise one solvent or a mixture of two or more solvents. If more than one solvent is present, such solvents can be in any weight or volume ratio relative to each other.

[0087] In still further aspects, the salt can be present in the electrolyte in any amount that provides the desired conductivity and can be dictated by the solubility of the salt in a specific solvent. In certain aspects, the salt is present in an amount of 0.01 M toAttorney Docket No.10046-611WO1 8386 MAN 3 M, including exemplary values of 0.05 M, 0.1 M, 0.2 M, 0.3 M, 0.4 M, 0.5 M, 0.6 M, 0.7 M, 0.8 M, 0.9 M, 1 M, 1.1 M, 1.2 M, 1.3 M, 1.4 M, 1.5 M, 1.6 M, 1.7 M, 1.8 M, 1.9 M, 2 M, 2.1 M, 2.2 M, 2.3 M, 2.4 M, 2.5 M, 2.6 M, 2.7 M, 2.8 M, and 2.9 M. In still further aspects, the salt can be present in any amount between any two foregoing values. In yet still further aspects, the sale can be present in an amount that falls within a range formed by any two values described above. For example, the salt can be present in an amount of 0.05 M to 3 M, 0.1 M to 3 M, 0.5 M to 3 M, 1 M to 3 M, about 1.5 M to 3 M, 2 M to 3 M, and so on. It is understood, however, that in certain aspects, when the solubility of the salt allows it, the salt can be present in an amount higher than 3 M, higher than 3.5 M, higher than 4 M, higher than 4.5 M, or even higher than 5 M.

[0088] In still further aspects, it is understood that the salt amount can be presented in different units, such as molality or weight (wt) %. In aspects where the salt amount is presented in wt%, the weight percent of the salt is calculated based on the total weight of the electrolyte.

[0089] Yet also disclosed herein are aspects where the electrolyte is a solid electrolyte. In still further aspects, the battery can comprise any solid or hybrid electrolyte known in the art. In certain aspects, the electrolyte is a solid electrolyte and comprises an inorganic ceramic / glass-ceramic, organic polymer, and ceramic- polymer composite electrolytes. For example, and without limitations, the solid electrolyte can comprise doped and undoped LISICON-type compounds, perovskite- type and anti-perovskite-type compounds, nitrides, oxynitrides, beta-alumina, Cryolite-type, argyrodite-type, or polymer-based electrolytes, or ceramic-polymer composite electrolytes, or any combination thereof. If the electrolyte is polymer- based electrolytes, such electrolytes can further comprise an alkali metal, an alkaline-earth metal salt, or a combination thereof.

[0090] In still further aspects, where batteries comprise a liquid electrolyte, for example, the battery can further comprise a separator. In such aspects, any known in the art separators that are capable of achieving the desired results can be used. For example, and without limitations, the separators can comprise glass fiber, a porous polymer film (e.g., polyethylene- or polypropylene-based material) with or without a ceramic coating, or a composite (e.g., a porous film of inorganic particlesAttorney Docket No.10046-611WO1 8386 MAN and a binder). One exemplary polymeric separator is a polyethylene (PE) membrane. Another exemplary polymeric separator is a polypropylene (PP) membrane. Another exemplary polymeric separator is a Celgard® 2500 polypropylene membrane. The separator may be infused with any of the disclosed herein electrolytes.

[0091] In still further aspects, the battery can operate at a voltage of 2.0 V to 4.4 V, including exemplary values of 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 4.1, 4.2, and 4.3 V. In still further aspects, the battery can operate at any voltage that falls between any two foregoing values or within the range formed by any two foregoing various. For example, the battery can operate at a voltage of 2.0 V to 4.5 V, 2.0 V to 4.3 V, 2.0 V to 3.5 V, 2.0 to 3.0 V, 2.5 V to 4.3 V, 2.5 V to 4 V, 2.5 V to 3.5 V, 2.5 V to 3 V, 3 V to 4.4V, 3.5 V to 4.4 V, 4 V to 4.4 V, 3.6 V to 4.3 V, 3.6 V to 4 V, 3.6 V to 3.8 V, and so on.

[0092] In still further aspects, the batteries disclosed herein can exhibit a capacity retention of at least 75% over at least 200 cycles. Yet in still further aspects, the batteries disclosed herein can exhibit capacity retention of at least 75% over at least 500 cycles. In yet still further aspects, the battery exhibits a capacity retention of at least 75%, at least 80%, at least 85%, at least 90%, at least 95%, and at least 99% over at least 500 cycles. It is understood that such capacity retention can also be observed for at least 700 cycles, at least 1,000 cycles, at least 5,000 cycles, at least 10,000 cycles, or at least 20,000 cycles.

[0093] In still further aspects, the batteries disclosed herein can exhibit a Coulombic efficiency greater than 80%, greater than 85%, greater than 90%, greater than 95%, or greater than 99% over at least 500 cycles. It is understood that such Coulombic efficiency can also be observed for at least 700 cycles, at least 1,000 cycles, at least 5,000 cycles, at least 10,000 cycles, or at least 20,000 cycles.

[0094] In still further aspects, the secondary batteries disclosed herein are capable of operating in a temperature range from -30 °C to 60 °C, including exemplary values of -25 °C, -20 °C, -15 °C, -10 °C, -5 °C, 0 °C, t 5 °C, 10 °C, 15 °C, 20 °C, 25 °C, 30 °C, 35 °C, 40 °C, 45 °C, 50 °C, and 55 °C. It is further understood that the batteries can operate at any value that falls between any foregoing values on in any range or in any range that is formed by the disclosed values. For example, the secondaryAttorney Docket No.10046-611WO1 8386 MAN batteries disclosed herein are capable of operating in a temperature range from -25 °C to 60 °C, -10 °C to 60 °C, 0 °C to 60 °C, 10 °C to 60 °C, 20 °C to 60 °C, 30 °C to 60 °C, or 40 °C to 60 °C, or -30 °C to 50 °C, -30 °C to 40 °C, -30 °C to 30 °C, -30 °C to 20 °C, -30 °C to 10 °C, t -30 °C to 0 °C, and so on.

[0095] In still further aspects, the batteries disclosed herein exhibit a specific capacity of 100 mAh g-1to 400 mAh g-1at a discharge rate of at least 0.1C. For example, the batteries can exhibit a specific capacity of 100 mAh g-1to 400 mAh g-1, including exemplary values of 110 mAh g-1, 120 mAh g-1, 145 mAh g-1, 150 mAh g-1, 200 mAh g-1, 250 mAh g-1, 300 mAh g-1, and 350 mAh g-1, at a discharge rate of at least 0.1C, of at least 0.2C, of at least 0.5C, of at least 1C, of at least 2C, of at least 3C, of at least 4C, of at least 5C, and so on. It is understood that the specific capacity can fall between any disclosed above values or can fall within any range formed by the disclosed above values. In certain aspects, the batteries disclosed herein exhibit a specific capacity of 100 mAh g-1to 400 mAh g-1, 145 mAh g-1to 400 mAh g-1, 200 mAh g-1to 400 mAh g-1, 300 mAh g-1to 400 mAh g-1, 100 mAh g-1to 350 mAh g-1, 100 mAh g-1to 300 mAh g-1, 100 mAh g-1to 250 mAh g-1, 100 mAh g-1to 200 mAh g-1, 110 mAh g-1to 190 mAh g-1, 120 mAh g-1to 180 mAh g-1, 130 mAh g-1to 170 mAh g-1, 140 mAh g-1to 160 mAh g-1, and so on at any of the disclosed above discharge rates.

[0096] By way of example, the secondary batteries of the present disclosure may be used in portable batteries, including those in hand-held and / or wearable electronic devices, such as a phone, watch, or laptop computer; in stationary electronic devices, such as a desktop or mainframe computer; in an electric tool, such as a power drill; in an electric or hybrid land, water, or air-based vehicle, such as a boat, submarine, bus, train, truck, car, motorcycle, moped, powered bicycle, airplane, drone, other flying vehicle, or toy versions thereof; for other toys; for energy storage, such as in storing electric power from wind, solar, wave, hydropower, or nuclear energy and / or in grid storage, or as a stationary power store for small-scale use, such as for a home, business, or hospital.

[0097] In addition, according to the present disclosure, the batteries can be multi-cell batteries containing at least 10, at least 100, at least 500, between 10 and 10,000, between 100 and 10,000, between 1,000 and 10,000, between 10 and 1000,Attorney Docket No.10046-611WO1 8386 MAN between 100 and 1,000, or between 500 and 1,000 individual batteries of the present disclosure. Cells in multi-cell batteries may be arranged in parallel or in series. METHODS

[0098] Also disclosed herein are methods of making any of the disclosed above cathode materials. In certain aspects,

[0099] In the exemplary methods disclosed herein, the cathode material can be formed from (a) a mixture comprising: (i) a precursor having a general formula Lia'Mnx'Fey'Mz'O4 and comprising one or more phases, wherein one or more phases is a spinel phase present in an amount of at least 95 wt% based on the total weight of all phases; (ii) a phosphorous source; (iii) a lithium source; and (iv) a carbon source; (b) forming a plurality of particles; and (c) heating the plurality of particles to form the structure comprising LiaMnxFeyDz(PO4)c.

[0100] It is understood that the precursor used in step a) can have any elements that are disclosed above. In such aspects, a’, x’, y’, and z’ can fall within any ranges disclosed above.

[0101] In still further aspects, the mixture further comprises water. In such exemplary and limiting aspects, the method further comprises homogeneously mixing and ball milling the mixture to form a slurry. In still further aspects, the slurry is then spray- dried to form a plurality of particles. In still further aspects, the plurality of particles are heated at a temperature of 550-800 °C, including exemplary values of 575 °C, 600 °C, 625 °C, 650 °C, 675 °C, 700 °C, 725 °C,750 °C, 775 °C, and 790°C. It is understood that the heating temperature can have any value between any two foregoing values, or it can fall within any range formed by any two disclosed values. In some aspects, the plurality of particles are heated at 575 °C to 800 °C, 600 °C to 775 °C, 625 °C to 750 °C, 650 °C to 725 °C, 550 °C to 775 °C, 550 °C to 750 °C, 550 °C to 725 °C, 550 °C to 700 °C, 550 °C to 675 °C, 550 °C to 650 °C, 550 °C to 625 °C, 550 °C to 800 °C, 575 °C to 800 °C, 600 °C to 800 °C, 625 °C to 800 °C, 650 °C to 800 °C, 675 °C to 800 °C, 700 °C to 800 °C, and so on.

[0102] In still further aspects, the heating is performed under an inert atmosphere. For example, in the presence of nitrogen or argon. In yet still further aspects, theAttorney Docket No.10046-611WO1 8386 MAN heating is performed for 0.5 to 4 hours, including exemplary values of 1 h, 1.5 h, 2 h, 2.5 h, 3 h, or 3.5 h. It is understood that the heating time can have any value between any two foregoing values, or it can fall within any range formed by any two disclosed values. In some aspects, the heating time is 0.5 h to 3.5 h, 0.5 h to 3 h, 0.5 h to 2.5 h, 0.5 h to 2 h, 0.5 h to 1.5h, 1 h to 4 h, 1.5h to 4 h, 2.5 h to 4 h, and so on.

[0103] It is understood that in such aspects, the cathode material having the disclosed structure is formed. In still further aspects, in the described methods, the coating is also formed.

[0104] In yet other aspects, the methods can form the disclosed in step (a) mixture but keeping an amount of carbon source separately from the main mixture. The remaining mixture is mixed and ball-milled to form a paste or slurry in the presence of water, which is then dried in an oven or vacuum oven. The resulting powder is then heat treated to crystallize the olivine phase, and then is ball milled again along with the remaining portion of the carbon source and water. The resulting slurry is spray-dried to form a powder, which is heat treated again to form the carbon coating. It is understood that the heating to form the olivine phase and carbon coating is performed at any of the mentioned above temperatures.

[0105] A more detailed method steps are described below.

[0106] The powder is placed in a furnace under nitrogen or argon gas flow, and the furnace is heated at a rate of 5 to 20°C per minute to a first temperature of 300 to 450°C and held at the first temperature for 0.25 to 2 hours. Subsequently, the furnace is heated at a rate of 5 to 20°C per minute to a second temperature of 550 to 750°C and held at the second temperature for 0.5 to 4 hours. In certain aspects, the temperature ramp rate is 10°C per minute, the first temperature is 350°C, and is held for 1 hour, and the second temperature is 650°C, and is held for 2 hours.

[0107] In other aspects, the slurry or paste can be dried in an oven, either under vacuum or ambient air, at a temperature of 90 to 120 °C. The resulting material is then pulverized to a fine powder, for example, using a ball mill, a jet mill, or a mortar and pestle. The resulting powder is then placed in a furnace under nitrogen or argon gas flow, and the furnace is heated at a rate of 5 to 20°C per minute to a first temperature of 300 to 450°C and held at the first temperature for 0.25 to 2 hours. Subsequently, the furnace is heated at a rate of 5 to 20°C per minute to a secondAttorney Docket No.10046-611WO1 8386 MAN temperature of 450 to 650°C and held at the second temperature for 0.5 to 4 hours. The resulting material is mixed with water, one or more of the previously described carbon sources, and one or more of the previously described polymers, and then the mixture is ball-milled to form a slurry. This slurry is spray-dried to form spherical secondary particles. The resulting powder is loaded into a furnace under nitrogen or argon flow, and then the furnace is heated at a rate of 5 to 20°C per minute to a third temperature of 550 to 750°C and held at the third temperature for 0.5 to 2 hours. In still further aspects, the temperature ramp rate can be 10°C per minute, the first temperature can be 350°C and can be held for 1 hour, the second temperature can be 550°C and can be held for 1 hour, the third temperature can be 650°C and can be held for 1 hour.

[0108] In still further aspects, the phosphorous source comprises a phosphoric acid, an organic or inorganic salt of phosphoric acid, or any combination thereof. For example, and without limitations, the phosphorous source can comprise H3PO4, NH4H2PO4, (NH4)2HPO4, LiH2PO4, Li3PO4, or any combination thereof.

[0109] In still further aspects, the Li source comprises LiOH, Li2CO3, LiH2PO4, Li3PO4, another organic and / or inorganic lithium salt, or a combination thereof. Any known in the art organic and inorganic salts of lithium can be utilized. For example, and without limitations, it can be a Li salt of carboxylic acid, for example, lithium acetate, lithium citrate, lithium oxalate, and so on.

[0110] In still further aspects, the carbon source comprises a mixture of at least one sugar and / or carboxylic acid compound and at least one polymer. For example, and without limitations, the carbon source can comprise at least one sugar comprising glucose, dextrose, sucrose, lactose, maltodextrin, cyclodextrin, dextrin, starch, or a combination thereof. Yet, in other aspects, the carboxylic acid compound comprises citric acid, ascorbic acid, oxalic acid, or a combination thereof.

[0111] In still further aspects, the polymer comprises polyethylene glycol, polyethylene oxide, polyvinyl alcohol, polyvinyl pyrrolidone, polyamide, polyimide, sodium carboxymethylcellulose, hydroxyethyl cellulose, hydroxymethyl cellulose, or any combination thereof.

[0112] In certain aspects, more than one sugar can be present. For example, the carbon source can comprise a mixture of lactose, maltodextrin, and sodiumAttorney Docket No.10046-611WO1 8386 MAN carboxymethyl cellulose, such that the weight ratio of lactose to maltodextrin is between 1:2 and 2:1, or even 1:1 to 1:1.5, and such that the sodium carboxymethyl cellulose comprises less than 5 wt%, less than 4 wt%, less than 3 wt%, less than 2 wt%, or less than 1 wt%, of the carbon source.

[0113] The water content of the slurry can be between 30 to 50 wt%, 35 to 50 wt%, 40 to 50 wt%, 35 to 45 wt%, 35 to 40 wt%, 30 to 45 wt%, and so on.

[0114] Any known in the art methods of ball milling can be used. In certain aspects where stainless steel or zirconia milling media is used with a size of between 1 to 10 mm, and the total milling time is between 30 minutes and 2 hours.

[0115] In still further aspects, the formed mixture can further comprise one or more processing aids. It is understood that the processing aids can include any known in the art dispersants, pH adjusters, pore-forming agents, binders, drying aids, any combination thereof, and so on.

[0116] The pH adjuster can be ammonium hydroxide, for example. The pH of the slurry can be kept anywhere between 3 to 6 or 4 to 5. The pore-forming agent can be one or more oxalate salts and / or oxalic acid. In some implementations the pore- forming agent can be H2C2O4, Li2C2O4, FeC2O4, MnC2O4, FexMn1-xC2O4, MgC2O4•, CoC2O4, ZnC2O4, NiC2O4, or a combination thereof. In some aspects, the oxalate salt can be a hydrate, for example, FeC2O4•2H2O, MnC2O4•2H2O, FexMn1- xC2O4•2H2O, MgC2O4•2H2O, CoC2O4•2H2O, ZnC2O4•2H2O, NiC2O4•2H2O, or any combination thereof.

[0117] In still further aspects, the precursor having a general formula Lia'Mnx'Fey'Mz'O4 comprising one or more phases, wherein one or more phases is a spinel phase present in an amount of at least 95 wt % based on total weight of all phases is formed by: (a) forming a mixture comprising: (i) an iron source (ii) a manganese source, and (iii) a lithium source; (b) heating the mixture to a temperature of 800 to above 1000 °C to form the precursor. In still further aspects, and as disclosed above, M comprises Al3+and Si4+. In still further aspects, the mixture further comprises a source of M that is different from Mn and Fe. In certain aspects, M is also referred to as a dopant and sometimes as an impurity, dependingAttorney Docket No.10046-611WO1 8386 MAN on the context of whether it originates from an iron source, a manganese source, and / or a lithium source, or if it is added separately.

[0118] It is understood that in the aspects disclosed herein, the source materials can be very pure or can have lower purity and, therefore, lower cost.

[0119] For example, and without limitations, disclosed herein are aspects where the iron source, manganese source, lithium source, or a combination thereof have a purity of greater than 98%, greater than 98.5%, greater than 99%, greater than 99.5%, or greater than 99.9%.

[0120] Yet also disclosed are aspects where the iron source, manganese source, lithium source, or a combination thereof have a purity of less than 98%, less than 97.5%, less than 97%, less than 96.5%, less than 96%, less than 95.5%, less than 95%. In still further aspects, the source of iron, manganese, and lithium can have purity of 93% to 98%, 94% to 98%, or 95% to 97%, and so on. In some aspects, the iron source, manganese source, lithium source, or a combination thereof can have a purity of less than 50%, less than 60%, less than 70%, less than 80%, less than 90%, or less than 95%. In some aspects the iron source, manganese source, lithium source, or a combination thereof can have a purity from 50-98.5%, from 60-98.5%, from 70-98.5%, from 80-98.5%, from 90-98.5%, from 95-98.5%, from 90-95%, from 80-90%, from 70-80%, from 70-90%, from 50-90%, from 60-90%, from 50-60%, or from 60-70%.

[0121] In aspects where the iron source, manganese source, lithium source, or a combination thereof have a purity of less than 98%, the iron source, for example, can be an iron oxide, an iron ore, a concentrated iron ore, iron metal, an iron alloy, or a combination thereof. In aspects where the iron source, manganese source, lithium source, or a combination thereof have a purity of less than 98%, the manganese source can be a manganese oxide, a manganese ore, a concentrated manganese ore, manganese metal, a manganese alloy, or a combination thereof. In aspects where the iron source, manganese source, lithium source, or a combination thereof have a purity of less than 98%, the lithium source comprises a lithium brine, a concentrated lithium brine, a precipitate of a lithium brine, a lithium ore, a concentrated lithium ore, another source of lithium with a purity of less than 98%, or a combination thereof.Attorney Docket No.10046-611WO1 8386 MAN

[0122] Any of the disclosed herein ores can be low-grade ores, high-grade ores, ore concentrates, technical grade oxides, or alloys such as steel or ferromanganese for Fe and / or Mn sources.

[0123] It is understood that any of the method steps, either precursor or the final cathode material, can also be doped with additional elements that are disclosed as D or M in the structures above. Dopants can be added in any suitable form. For example, and without limitations, the dopant sources can include at least one of Mg(OH)2, NiO, Ni(OH)2, MgC2O4, ZnO, ZnC2O4, Co3O4, CoC2O4, B2O3, Al2O3, Cr2O3, SiO2, TiO2, ZrO2, V2O5, NH4VO3, or Nb2O5. In some aspects, the dopant source can include one or more of ZnC2O4•2H2O, MgC2O4•2H2O, CoC2O4•2H2O,

[0124] The disclosed precursor can then be synthesized by mixing a lithium source, a manganese source, an iron source, and optionally one or more dopant sources, then heating the mixture in air. For example, the lithium source can be Li2CO3 or LiOH, for example LiOH•H2O, the manganese source contains one or more of MnCO3, Mn3O4, Mn2O3, MnO2, or ferromanganese alloy, the iron source contains one or more of FeC2O4 (including FeC2O4•2H2O), Fe3O4, Fe2O3, FeOOH, or iron metal, and the dopant source may comprise an oxide, hydroxide, oxalate, or other salt of one or more of Mg, Ni, Co, Zn, B, Al, V, Cr, Si, Ti, Zr or Nb. It is understood that some of these dopants or additives can be added to the mixture before processing. The lithium source, manganese source(s), iron source(s), and dopant source(s) are intimately mixed, for example, by grinding or ball milling, then the mixture is heated in air at a temperature of 800 °C to 1000 °C, 800 ° to 950°, 850 °C to 950 °C, 850 °C to 1000 °C, or 900 ° to 1000 °C, or 950 ° to above 1000 °C. In still further aspects, the mixture is heated for a time of 1 to 12 hours, 2 to 12, 3 to 12, 4 to 12, 5 to 12, 6 to 12, 7 to 12, 8 to 12, 9 to 12, 10 to 12, 1 to 10, 1 to 8, 1 to 6, 2 to 8, 2 to 6, 2 to 4, and so on.

[0125] In still further aspects, and as disclosed above, the lithium, iron, and manganese sources can have a purity (by mole basis of combined Li, Mn, and Fe versus total metals) of < 99%, or between about 95% and 99%. In some aspects, the lithium, iron, and manganese sources can have a purity of less than 50%, less than 60%, less than 70%, less than 80%, less than 90%, or less than 95%. In some aspects the iron source, manganese source, lithium source, or a combination thereofAttorney Docket No.10046-611WO1 8386 MAN can have a purity from 50-98.5%, from 60-98.5%, from 70-98.5%, from 80-98.5%, from 90-98.5%, from 95-98.5%, from 90-95%, from 80-90%, from 70-80%, from 70- 90%, from 50-90%, from 60-90%, from 50-60%, or from 60-70%.

[0126] In still further aspects, the mixture can further comprise an alkali base. In such aspects, the alkali base can comprise sodium hydroxide, sodium carbonate, sodium bicarbonate, potassium hydroxide, potassium carbonate, potassium bicarbonate, and any combination thereof.

[0127] It is understood that since the initial source(s) can be less than 98% pure, the formed precursor can comprise at least one impurity present within the Spinel phase, and can comprise at least one other phase comprising soluble impurities and / or at least one other phase comprising insoluble impurities. It is understood that the at least one impurity present in the Spinel phase can comprise Mg, Ni, Co, Zn, Cu, Al, V, Cr, Ti, Zr, and / or Nb. Yet in still further aspects, the at least one impurity in the Spinel phase can comprise Mg, Zn, Al, and / or Ti. The soluble impurities can include Na, K, Ca, Ba, B, Sr, Si, P, and Al. In certain aspects, a portion of the soluble impurities can be removed by dissolving the impurities in water. The insoluble impurities can include Al, B, Si, and P. In certain aspects, a portion of the insoluble impurities can be converted into soluble impurities by reacting with an alkali base. In such aspects, a portion of the insoluble impurities can be removed by reacting the insoluble impurities with an alkali base to convert them to soluble impurities, then dissolving the resulting soluble impurities in water. It is understood that the removal of the insoluble impurities is controllable by the amount of alkali base added, and that the desired amounts of Al and / or Si can be kept in the resulting precursor by adjusting the amount of alkali base relative to the amount of insoluble impurities present in the precursor. In such aspects, the total amount of impurity elements selected from the group of Na, K, Ca, Ba, and Sr is less than 10 mole%, less than 5 mole%, or less than 1 mole%, of the total amount of impurities present.

[0128] In still further aspects, a portion of the insoluble impurities is removed by a magnetic separation. Since the spinel precursor is ferrimagnetic, substantially all non-magnetic impurities can be separated from the spinel precursor by a magnetic separation.Attorney Docket No.10046-611WO1 8386 MAN

[0129] The present disclosure uses a synthesis process typically employed for low- cost oxide cathode active materials (i.e., LiMn2O4 or LiNi0.5Mn1.5O4) to instead form a low-cost LiMn2-xFexO4 (LMFO) precursor for the synthesis of high-performance lithium manganese iron phosphate (LiMn1-xFexPO4) active material. The unique properties of the LMFO precursor, particularly its improved resistance to acid dissolution compared to any other known atomically mixed Mn / Fe oxides, yield improved slurry processability, improved cathode material tap density, and reduced manufacturing cost. Additionally, the unique properties of the Spinel crystal structure of LMFO allow impurities which are generally beneficial for the performance of LMFP, for example Mn2+and Ti4+, to enter the Spinel crystal structure of LMFO, while the impurities which are generally detrimental to the performance of LMFP, for example Na+, K+, and Ca2+, are incapable of substantially entering the Spinel crystal structure of LMFO. Finally, the unique combination of the electronic structures of Fe3+and Mn4+, and the Spinel crystal structure of LMFO, cause the LMFO precursor to be highly ferrimagnetic, and as such is strongly attracted to an applied magnetic field, which enables the use of magnetic separations.

[0130] The present disclosure, unlike most manufacturing methods for Li-ion battery active materials, utilizes raw materials of relatively low purity (i.e., 98%). Current technologies for LMFP synthesis involve either (1) ball milling of separate Mn and Fe sources, such as Mn3O4 and FePO4, or (2) coprecipitation of a mixed Mn / Fe phosphate precursor, and typically require the use of high-purity raw materials. In the first process, it is challenging to achieve uniform atomic scale mixing of Mn and Fe since low temperatures (i.e., < 700°C) and short times (i.e., < 2 hr) are required to prevent excessive crystal growth of the LMFP primary particles during heat treatment, which limits solid-state inter-diffusion of Fe and Mn. Consequently, the Fe and Mn precursors must be milled to very small particle sizes (i.e., < 100 nm), and the heat treatment must be precisely controlled to ensure uniform mixing of Mn and Fe, which increases the processing cost and presents issues for scalability. In the second method, soluble iron and manganese salts, such as FeSO4 and MnSO4, are mixed with a phosphorus source, such as H3PO4, to precipitate an atomically mixed precursor, such as NH4MnxFe1-xPO4•H2O. This coprecipitation process generates significant wastewater, typically containing Na2SO4 and NH3, which adds significant processing costs to treat and dispose of. Additionally, LMFP active materialsAttorney Docket No.10046-611WO1 8386 MAN synthesized from co-precipitation methods typically have lower tap density and press density than those synthesized from the first method, which lowers the energy density of the battery.

[0131] The current disclosure utilizes a heat treatment process to form an atomically mixed precursor rather than a co-precipitation process, which avoids the generation of wastewater. It was surprisingly found that using the disclosed methods steps, and more particularly the disclosed herein precursor having a spinel phase, the tap density and press density of the resulting LMFP powder is significantly higher than can be obtained with the methods from the prior art.

[0132] Also, disclosed herein is a method comprising: providing any of the disclosed herein cathode electrodes; providing any of the disclosed herein anode electrodes; providing any of the disclosed herein electrolytes; and providing any of the disclosed herein separators; forming any of the disclosed herein secondary batteries.

[0133] By way of a non-limiting illustration, examples of certain aspects of the present disclosure are given below. EXAMPLES

[0134] The following examples are put forth so as to provide those of ordinary skill in the art with a complete disclosure and description of how the compounds, compositions, articles, devices, and / or methods claimed herein are made and evaluated and are intended to be purely exemplary and are not intended to limit the disclosure. Efforts have been made to ensure accuracy with respect to numbers (e.g., amounts, temperature, etc.), but some errors and deviations should be accounted for. Unless indicated otherwise, parts are parts by weight, temperature is degrees C or is at ambient temperature, and pressure is at or near atmospheric.

[0135] For LMFP to achieve a reduced cell-level cost per kWh compared to LFP, the cost of the LMFP powder must be equivalent to that of LFP. While the raw material costs of Mn and Fe are similar, the more complex methods often employed to synthesize high-performance LMFP (e.g., hydrothermal) can add significant processing costs. Generally, commercial LFP is manufactured by two methods: (i) a precipitation reaction of FeSO4, H3PO4, and H2O2 to form FePO4, followed by a solid- state reaction with Li2CO3, or (ii) a direct reaction of Li2CO3 and H3PO4 with a FeAttorney Docket No.10046-611WO1 8386 MAN source such as Fe2O3. Spray drying is often employed, either before or after the synthesis of the olivine phase, to densely agglomerate the primary particles into spherical secondary particles, which significantly improves the tap density. Due to the low synthesis temperature (i.e., 650°C) and short time (i.e., < 2 h) required to prevent sintering of the LMFP primary particles, ensuring intimate mixing of Mn and Fe at the atomic / molecular level in the LMFP precursor is critical to avoid the formation of Mn-rich particles, as they would experience more severe kinetic limitations. Co-precipitation of a phosphate precursor, such as NH4MnxFe1- xPO4•H2O, is a viable route to ensure atomic level mixing of Mn and Fe and can produce LMFP cathodes with high specific capacity. However, co-precipitation synthesis produces large amounts of wastewater, which is expensive and energy- intensive to treat and typically results in LMFP powders with low tap density. The direct synthesis of LFP with Fe2O3 has been shown to yield very high density LFP cathodes while avoiding waste generation, but such an approach has not been studied widely for LMFP. This is because achieving sufficiently intimate atomic-scale mixing of separate oxide precursors (e.g., Mn2O3 and Fe2O3) by scalable processes, such as ball milling, is extremely challenging.

[0136] In this work, LiMnFeO4 (LMFO) with the spinel structure, in which Mn and Fe are bonded at an atomic level, is employed as a precursor for the synthesis of LiMn0.5Fe0.5PO4 cathode, which is hereafter referred to as S-LMFP. The material properties and electrochemical performance of S-LMFP are compared with those of an LMFP cathode with the same composition that is synthesized with a conventional co-precipitation method, which is hereafter referred to as P-LMFP. Through rate performance testing of LMFP electrodes with various press densities, the maximum achievable electrode-level volumetric energy density of the two materials is compared. It is shown that, despite its lower specific capacity, S-LMFP significantly outperforms P-LMFP in volumetric energy density due to its much higher achievable electrode density. By electrochemical testing at different temperatures, the lower capacity of S-LMFP is found to be a result of sluggish Li+diffusion kinetics during Mn2+ / 3+redox, which are caused by the larger primary particle size. Overall, it is suggested that achieving a maximum energy density with LMFP cathodes requires a careful balancing between the electrode density and Mn2+ / 3+redox kinetics through a careful selection of precursors and optimization of synthesis conditions.Attorney Docket No.10046-611WO1 8386 MAN METHODS MATERIALS PREPARATION

[0137] To synthesize the LMFO precursor, first 21.48 g of Fe2O3 and 19.35 g of MnO2 (both 98%, Thermo Scientific) were mixed with approximately 125 mL of deionized water in a 250 mL high-density polyethylene bottle, and the mixture was milled on a roller jar mill (U.S. Stoneware) with 3–10 mm zirconia media for 72 h. Both the Fe2O3 and MnO2 contained impurities of both Al and Si, based on energy dispersive X-ray spectroscopy. After drying the milled mixture for 12 h at 110 °C, a stoichiometric amount of LiOH·H2O (99.9%, FMC Corporation) was mixed with the metal oxides by grinding with a mortar and pestle to give nominal compositions ranging from Li0.90MnFeO4 to Li1.10MnFeO4. A composition of Li0.95MnFeO4 was used for the synthesis of LMFP. The mixture was calcined in a box furnace at 500 °C for 3 h, followed by 900 °C for 6 h, with a heating rate of 5 °C per min.

[0138] The phosphate precursor, NH4Mn0.5Fe0.5PO4•H2O,was synthesized by a co- precipitation reaction. The metal-ion solution (250 mL) contained 0.50 M FeSO4•7H2O (98%, Thermo Scientific), 0.50 M MnSO4•H2O (99+%, Thermo Scientific), and 1.00 M H3PO4 (ACS reagent, Sigma-Aldrich). The base solution (100 mL) contained 5.00 M NH4OH (Certified ACS Plus, Fisher Chemical). A 2 L reaction vessel was initially filled with 350 mL of a solution containing 0.07 M H3PO4 and 0.07 M NH4OH. The metal-ion and base solutions were added dropwise to the reaction vessel with a peristaltic pump at flow rates of, respectively, 3.63 and 1.43 mL min-1. A temperature of 80 °C, a pH of 8, and continuous stirring at 450 rpm were maintained during the reaction. After cooling, the precipitated product was filtered, rinsed thoroughly with deionized water, and dried overnight at 110 °C under vacuum.

[0139] Three separate LMFP samples with a 50:50 molar ratio of Mn:Fe were prepared for this study: LMFP from LMFO (S-LMFP), LMFP from NH4Mn0.5Fe0.5PO4•H2O (P-LMFP), and LMFP from MnO2 and Fe2O3 (O-LMFP). Each sample had a nominal molar composition of Li1.06Mn0.475Fe0.475V0.02Mg0.02Co0.01(PO4)1.025 and a nominal carbon content of 3 wt%. In this non-limiting example, 2% V, 2% Mg, and 1% Co were selected as exemplary dopants in order to compare the performance of LMFP synthesized with the sameAttorney Docket No.10046-611WO1 8386 MAN composition but from different precursors. However, it will be appreciated by those skilled in the art that similar electrochemical performance can be achieved if V, Mg, and / or Co are partially and / or fully substituted by one or more other suitable dopants, for example Zn, Ni, Al, Cr, Ti, Zr, Si, and / or Nb.

[0140] FIG.1 depicts the two-step carbon coating synthesis process of S-LMFP, which was mimicked for the synthesis of the other two LMFP samples. For this process, LMFO was combined with Li3PO4 (Thermo Scientific, extra pure) or Li2CO3 (Sigma-Aldrich, ACS reagent) and NH4H2PO4 (Sigma-Aldrich, 98.5%). The molar ratios of Li, Mn, Fe, and PO4 were, respectively, 1.06:0.5:0.5:1.025. Cobalt (1 mol%), magnesium (2 mol%), and vanadium (2 mol%) were added as additional dopants to each sample in the form of, respectively, CoC2O4•2H2O (Thermo Scientific, reagent grade), MgC2O4•2H2O (Alfa Aesar, 98.5%), and NH4VO3 (Acros Organics, 98%). 50% of the total carbon in the synthesis was added during the first milling step in the form of a 1:1 weight ratio between citric acid monohydrate (Sigma-Aldrich, >99.0%) and glucose (MP Biomedicals, molecular biology grade).

[0141] For S-LMFP, 0.060 mol of LMFO was combined with 0.024 mol of Li3PO4, 0.104 mol of NH4H2PO4, 1.25 mmol of CoC2O4•2H2O, 2.50 mmol of MgC2O4•2H2O, 2.50 mmol of NH4VO3, 1.44 g of citric acid, 0.88 g of glucose, and 13 mL of deionized water. For P-LMFP, 0.057 mol of NH4Mn0.5Fe0.5PO4•H2O was combined with 0.032 mol of Li2CO3, 4.23 mmol of NH4H2PO4, 0.60 mmol of CoC2O4•2H2O, 1.21 mmol of MgC2O4•2H2O, 1.21 mmol of NH4VO3, 0.55 g of citric acid, 0.33 g of glucose, and 14 g of deionized H2O. For O-LMFP, 0.028 mol of Fe2O3 and 0.056 mol of MnO2 were combined with 0.042 mol of Li3PO4, 0.040 mol of NH4H2PO4, 1.19 mmol of CoC2O4•2H2O, 2.38 mmol of MgC2O4•2H2O, 2.38 mmol of NH4VO3, 1.37 g of citric acid, 0.84 g of glucose, and 13 mL of deionized water.

[0142] The precursors and carbon sources were milled in solution in an 80 mL stainless steel ball mill jar with 70 g of 5 mm diameter stainless steel media using a Fritsch Pulverisette 6 planetary ball mill for 6 h at 450 rpm. The viscosity of this solution was high to ensure a uniform distribution of all precursors. The milled product was dried under vacuum at 110 °C to evaporate all the water and then calcined at 550 °C for 3 h under Ar flow to produce an intermediate product. This powder was combined with the remaining 50% of carbon in the form of lactoseAttorney Docket No.10046-611WO1 8386 MAN (ChemCenter, reagent grade) with a mass of 1.85 g, 0.70 g, and 1.76 g, respectively, for S-LMFP, P-LMFP, and O-LMFP. A total of 3 wt% ± 0.2 wt% carbon was coated onto the calcined LMFP samples (unless otherwise noted).5.25 mg carboxymethyl cellulose (CMC) (Nippon Paper, Sunrose MAC Series) was added to the solution as a dispersant. After milling for 1 h at 450 rpm in H2O, the resultant solution was fed into a Labfreez benchtop spray dryer at a rate of 2 mL min-1and a solid loading of 52%. The spray gun was pressurized to 0.15 MPa with air, and the airflow rate through the spray dryer was set at 18 scfm. The inlet temperature was maintained at 130oC, and the resultant exhaust temperature remained around 105 °C. The collected spray-dried product was calcined at 650 °C for 2 h under Ar flow to form LMFP.

[0143] Characterizations. Structural properties of the various LMFO and LMFP samples were examined with X-ray diffraction (XRD) with Cu Kα radiation (Rigaku Miniflex). XRD was conducted at a scan rate of 2oper min. Rietveld refinement analysis was conducted with Rigaku PDXL integrated powder XRD software. The morphologies of the spray-dried LMFP samples were examined with scanning electron microscopy (SEM). SEM was paired with energy dispersive x-ray spectroscopy (EDS) to examine the metal-ion distribution in the precursors, and SEM-EDS images were captured on a Tescan Vega3 SEM. SEM-EDS was conducted at a beam voltage of 10 kV. SEM was also paired with a focused ion beam (FIB) to investigate the secondary particle pore structure of the calcined LMFP samples, and the FIB-SEM images were captured on a Scios 2 DualBeam FIB-SEM. FIB-SEM was conducted at a beam voltage of 2 kV. Tap density measurement was conducted with a Quantachrome Autotap Tap Density Analyzer. Approximately 7 g of LMFP was massed into a 10 mL graduated cylinder and allowed to tap for 1 h at a rate of 3 taps per min. Final volume measurements were taken with ±0.01 cm3precision. Thermogravimetric analysis (TGA) was conducted with a Netzsch STA 449 F3 Jupiter Thermal Analyzer. The LMFP samples were heated to 700 spray- dried at a heating rate of 5 spray-dried min-1under airflow, and held at 700 spray- dried for 30 min to obtain a steady-state value at this final temperature. The carbon content was measured assuming a 2.5 wt% increase in weight from the oxidation of LMFP. Brunauer–Emmett–Teller (BET) surface area analysis based on nitrogenAttorney Docket No.10046-611WO1 8386 MAN physisorption isotherms was performed at 77 K with a Micromeritics TriStar II Plus. The LMFP samples were dried under vacuum overnight at 120°C prior to BET measurements.

[0144] Electrochemical measurements. All the LMFP samples were formed into cathodes via a slurry casting method. LMFP was dispersed in N-methyl-2- pyrrolidone (Sigma-Aldrich, 99.5%) with a conductive carbon mixture of Super C65 (Timcal) and vapor-grown carbon fibers (Resonac) in a 4:1 ratio by weight and polyvinylidene fluoride (Kynar HSV1800) binder. The compositions of the active material, conductive carbon, and binder were, respectively, 95:2.5:2.5 by weight. Slurry mixing was carried out in an ARV-310 Thinky mixer. The slurry was cast onto a carbon-coated Al foil at an aerial loading of 1.0 - 1.6 mA h cm-2,depending on the test conducted on the cathode. After casting, the cathode was dried at 110 °C to evaporate all the solvent and hot calendared at 110 °C between stainless steel shims to a specified press density. The cathodes were then stored under a vacuum at 110oC overnight to completely dry the electrode.

[0145] The LMFP cathodes prepared were punched into 1 / 2 in. (1.26 cm) diameter discs and were tested in 2032-type coin cells. Assembly of the coin cell was carried out inside an argon-filled glovebox. Half cells were composed with LMFP as the cathode, 50 μL of LP57 electrolyte with 2% vinylene carbonate by weight, a 3 / 4 in. diameter Celgard 2325 separator, and a 5 / 8 in. diameter lithium-metal anode. The LP57 electrolyte refers to 1.0 M LiPF6 in ethylene carbonate (EC) / ethylmethyl carbonate (EMC) (3:7 by weight). LMFP half cells were cycled from 2.0 to 4.3 V vs. Li / Li+at a C / 5 rate. A constant current / constant voltage charge procedure was used; a C / 5 rate current was applied until 4.3 V was reached, followed by a voltage hold at 4.3 V until the current dropped below the C / 25 rate. The discharge procedure did not include a constant voltage discharge step. Discharge rate testing was conducted with a C / 10 charge rate, followed by the specified discharge rate. All cycling and rate testing were conducted on an Arbin LBT-20084.

[0146] Electrochemical impedance spectroscopy (EIS) was conducted with a VMP3 Biologic potentiostat. Asymmetric cell was built with pristine LMFP as both the cathode and anode (5 / 8 in. diameter electrodes). The cell was flooded with 200 μL of a blocking electrolyte (BE): 1 M tetraethylammonium tetrafluoroborate (Sigma-Attorney Docket No.10046-611WO1 8386 MAN Aldrich, 99%) in acetonitrile (Fisher Chemical, ACS grade). This electrolyte is commonly used in electric double-layer capacitors, where no chemical reactions occur.31Therefore, BE does not allow intercalation of Li+ions into either electrode, leaving contact resistance as the sole variable investigated. In this study, contact resistance refers to the resistance between the active material and the current collector, conductive carbon matrix / electronic pathway in the cathode, and / or other active material particles. EIS was operated within the frequency range of 500 kHz to 100 MHz. EXAMPLE 1

[0147] In this example, first, the multiple oxide phases that contain both Fe and Mn were tested as precursors for high-density LMFP. A rock salt phase Fe0.5Mn0.5O was successfully synthesized by heating a mixture of Mn2O3, Fe2O3, and activated carbon under Ar flow at 800 °C. However, when mixed with an aqueous solution of NH4H2PO4, the Fe0.5Mn0.5O powder immediately reacted to form a viscous paste (FIG.2). Mn2+dissolution from Fe0.5Mn0.5O occurs rapidly under the mildly acidic pH (~ 4.5) of the NH4H2PO4 solution and the dissolved Mn2+reacts with oxygen to form MnOOH and Mn3O4. The costly synthesis conditions of Fe0.5Mn0.5O, combined with this unfavorable reaction during mixing, make this phase unsuitable as a precursor for scalable low-cost and high-density LMFP. Two other ternary Mn / Fe oxides were also investigated as precursors: spinel Fe1.5Mn1.5O4 and ilmenite FeMnO3. The Fe1.5Mn1.5O4 phase could not be synthesized with conventional solid-state methods due to the miscibility gap between Fe3O4 and Mn3O4 below 1,160 °C, which would require quenching from high temperature to form a metastable phase. FeMnO3 can successfully be synthesized by a sol-gel or hydrothermal synthesis, but it exhibits the same Mn dissolution issues as Fe0.5Mn0.5O. The electronic instability (Jann-Teller distortion) associated with the high-spin Mn3+:3d4caused a disproportionation in acidic solutions to form Mn4+and soluble Mn2+. To avoid these dissolution issues, an oxide phase containing Mn4+oxide could be employed, but there are no known binary Mn / Fe oxides with Mn4+. For example, since Fe4+is not chemically stable, the (Fe, Mn)O2 phase could not be formed. Considering that Li is also a necessary precursor for LMFP synthesis, the ternary Li / Mn / Fe oxide system was investigated.Attorney Docket No.10046-611WO1 8386 MAN

[0148] Among all the possible Li / Mn / Fe ternary oxide phases, it was identified that the Spinel LiMnxFe2-xO4 is an ideal oxide precursor for LMFO synthesis due to the atomic scale mixing of Li, Mn, and Fe in the spinel structure, the ease of synthesis of the spinel structure, and greater resistance to dissolution in acidic solutions due to the absence of Mn3+.

[0149] SEM imaging shows that the LMFO phase forms truncated octahedral crystals with a size of 1 – 5 μm, while the EDS mapping reveals a uniform distribution of Mn and Fe throughout the bulk of the spinel phase (FIG.3A-3C). For comparison, a NH4Mn0.5Fe0.5PO4•H2O precursor synthesized by a co-precipitation reaction, showing uniform distribution of Mn and Fe according to EDS, is given in FIG.4. The phase purity of LMFO was investigated with XRD as a function of synthesis temperature between 500 and 900 °C (FIG.3D). At 500 °C, the two main phases present are LiMn2O4 and Fe2O3. The preferential lithiation of MnO2 by LiOH can be attributed to the lower decomposition temperature of MnO2 compared to Fe2O3. The gradual disappearance of Fe2O3 as the synthesis temperature increases shows that Fe3+diffusion into the spinel structure is the rate-limiting step in the formation of LMFO. At 800 °C, the powder retains a slight red tint after calcination, indicating residual amounts of Fe2O3. Therefore, at least 900 °C was found to be an optimal synthesis temperature for LMFO.

[0150] Without wishing to be bound by any theory, it was hypothesized that the stoichiometry of Li also plays a large role in controlling the phase purity of LMFO. LMFO was synthesized with varying Li amounts ranging from 10 mol% deficient to 10 mol% excess (FIG.3E), and the phase purity was assessed with XRD. A trace amount of Li2MnO3 impurity is detected when an equimolar stoichiometric amount of Li is used, and the peak intensity of this impurity increases when excess Li is added. Again, without wishing to be bound by any theory, it was assumed that the reason for Li2MnO3 formation is rooted in the preference for Fe3+with a high-spin 3d5configuration for both the octahedral and tetrahedral sites of the spinel lattice, resulting in a zero octahedral-site stabilization energy (OSSE) for Fe3+. Therefore, some Fe3+ions tend to reside in the tetrahedral sites of LMFO rather than being completely in the octahedral sites, displacing some Li+and Mn4+from the spinelAttorney Docket No.10046-611WO1 8386 MAN structure. According to XRD, the Li2MnO3 impurity could be completely eliminated by simply using 5 mol% deficient Li in the synthesis.

[0151] Notably, many of the dopants commonly employed for LMFP can be incorporated into the LMFO precursor as well. For example, LMFO synthesized with 1 mol% of both Mg and Co is phase-pure according to XRD (FIG.5). Without wishing to be bound by any theory, it was assumed that the stoichiometry of Li may need to be adjusted according to the site preference and amount of the dopants. For example, Mg2+may tend to go into the tetrahedral sites due to its smaller ionic size and zero OSSE, while Co3+will tend to go into the octahedral sites due to its high OSSE. Most other common dopants for LMFP, such as Al, Ti, V, Cr, Ni, Zn, and Nb, can also be soluble in the LMFO spinel lattice. Thus, employing LMFO spinel as an oxide precursor for LMFP can offer the unique advantage of accommodating a variety of dopants at an atomic scale, in addition to its scalable, water-free synthesis.

[0152] In the LIB industry, it is generally believed that high-purity chemicals (i.e., > 99.9%) are required for the synthesis of high-performance cathode active materials. However, it was found that this belief is not necessarily true for olivine cathodes, including LFP and LMFP. Without wishing to be bound by any theory, it was hypothesized that the reason for such a phenomenon can be due to the olivine structure being substantially intolerant to lattice substitutions. For example, without wishing to be bound by any theory, it is assumed that with excess Li provided in the synthesis, the M1 site in the olivine structure will only be occupied by Li+, and thus, impurity ions will not block the Li+diffusion channels. The Fe2+or Mn2+in the M2 site of the olivine structure will only be substituted in appreciable quantities by ions of the same charge and similar size, like Mg2+, Zn2+, Ni2+, and Co2+. It will be appreciated by those skilled in the art that the substitution of Fe2+and / or Mn2+in LMFP by one or more isovalent ions selected from Mg2+, Zn2+, Ni2+, or Co2+is required to achieve maximum electrochemical performance. However, without wishing to be bound by any theory, it is understood that each of these elements can play essentially the same role in improving the electrochemical performance of LMFP, and thus, Mg2+, Zn2+, Ni2+, or Co2+are largely interchangeable as dopants. It is, therefore, the total concentration of isovalent dopants rather than their specific identity that controls the electrochemical performance of LMFP.Attorney Docket No.10046-611WO1 8386 MAN

[0153] Ions with a higher charge than 2+ (i.e., supervalent ions), such as Al3+, V3+, Ti4+, Zr4+, Si4+, Nb5+, or W6+, will segregate to the surface of the olivine particles once the concentration exceeds the solubility limit in the olivine crystal lattice. Without wishing to be bound by any theory, it is understood that the solubility limit of supervalent ions can be very low (i.e., < 1%) when excess lithium and phosphorous are provided in the synthesis. If the amount of supervalent ions is sufficient, then a secondary phase will form on the surface of the olivine nanoparticles, which may be either crystalline or amorphous. When the surface phase is amorphous, it may uniformly cover the olivine particle surface, while if it is crystalline, it may not uniformly cover the particle surface. If both a sufficient excess of lithium and phosphorus are used in the synthesis, and a sufficient amount of supervalent ions are present, then these supervalent ions may be present in the form of an amorphous phase which coats the surface of the olivine phase. Certain supervalent ions, specifically Si4+, are widely known to promote the formation of amorphous phases (i.e., glasses). It will be appreciated by those skilled in the art that providing one or more supervalent ions as a dopant is necessary to obtain the maximum electrochemical performance of LMFP. It is understood that certain supervalent ions, namely Al3+, V3+, Cr3+, Ti4+, Zr4+, and Nb5+,when heated with a lithium and phosphorus source, form a NASICON phase – for example, Li3V2(PO4)3 or LiTi2(PO4)3– which supports excellent 3-dimensional Li+-ion transport. Without wishing to be bound by any theory, it is further understood that the NASICON structure itself, rather than the specific identities of the ion(s) present in the structure, is responsible for the excellent Li+-ion transport properties. It is understood that the NASICON structure can accommodate relatively large concentrations of a wide range of other ions, including Na+, K+, Ca2+, Sr2+, and Ba2+, which are not soluble in the olivine structure. It is further understood that the NASICON structure contains two distinct crystallographic sites for cations, the M1 site and the M2 site, wherein the M1 site has a strong preference for cations with a valence of +1 such as Li+, Na+, and K+, wherein the M2 site has a strong preference for ions with a valence of +3 or more, such as Al3+, V3+, Cr3+, Ti4+, Zr4+, or Nb5+, and wherein the conduction and / or diffusion of Li+ions within the NASICON phase occurs substantially by the movement of Li+ions between adjacent M1 sites. Without wishing to be bound by any theory, it is still further understood that the presence of any cations other than Li+Attorney Docket No.10046-611WO1 8386 MAN in the M1 sites of the NASICON structure, such as Na+, K+, Ca2+, Sr2+, and Ba2+, would be generally detrimental to the kinetics of Li+migration and / or diffusion through the NASICON structure.

[0154] Without wishing to be bound by any theory, it is believed that if a sufficient amount of excess lithium and phosphorus and a sufficient amount of supervalent ions that can form the NASICON structure are provided in the synthesis, and a sufficiently low amount of impurities are present in the precursors, then these impurities can be incorporated into a Li+conductive surface coating on the olivine particle surface, which can enhance the electrochemical performance. In other words, through careful control of the added dopant composition based on an understanding of the fundamental chemistry, the impurity ions that may be present in low-purity precursors can be utilized as dopants, which improves the electrochemical performance. This allows the utilization of lower-cost raw materials with impurity ions without sacrificing the electrochemical performance, and reduces the amount of additional dopants that need to be provided in the synthesis.

[0155] The spinel precursor can be synthesized from essentially any mixture of iron and manganese sources, which may include metals or alloys, oxides, or other salts, such as oxalates or carbonates. It is advantageous to use the cheapest raw materials possible, which will be those with the least labor and energy use associated with their extraction and processing. Specifically, it would be highly advantageous to use iron and / or manganese ores as the raw materials for LMFP synthesis, as opposed to refined chemicals produced from those ores, like MnCO3 or FeC2O4. Most Mn ores contain significant Fe impurities, which is not problematic for the synthesis of LMFP. Most Mn and Fe ores also contain impurities of phosphorus, which is also not detrimental to the synthesis of LMFP. Very high-grade ores and / or ore concentrates for both Fe and Mn are widely produced, which may have purities on a metal basis of > 90%, sometimes > 95%, and sometimes > 98%. The most common impurities in Mn and Fe ores are (in approximate order of concentration) Si, Al, Mg, Ca, Na, K, Ti, and Zn. Other impurities, including but not limited to V, Cr, Co, Ni, Cu, Zr, Sr, and Ba, may also be present at amounts greater than 0.1% in certain ores.Attorney Docket No.10046-611WO1 8386 MAN

[0156] It is understood that low-grade ores can be concentrated by reacting the ore with an alkali base (such as sodium carbonate) at high temperatures (i.e., > 800°C), which converts some, or substantially all, of the impurities (i.e., Al2O3 and SiO2) to soluble compounds (i.e., NaAlO2 and Na2SiO3), which can be removed by washing with water.

[0157] Of the most common impurities present in Fe and Mn ores, it is understood that only Al, Mg, Zn, and Ti can be soluble in the spinel structure, while Si, Ca, Na, and K have substantially no solubility in the spinel structure. Of the less common impurities present in Fe and Mn ores, it is understood that V, Cr, Zr, Co, Ni, and Cu can be soluble in the spinel structure, while Sr and Ba have substantially no solubility in the spinel structure.

[0158] It is further understood that Mg, Zn, Ni, Co, Al, V, Cr, Ti, and Zr are all exemplary dopants for LMFP cathode materials, and that a mixture of any of these dopants can be effective at improving the electrochemical performance of LMFP in a range of about 1 mole% to about 5 mole% of the total transition metals present, that Si is an effective dopant at limited quantities (i.e., ~ 1-2 mole%) but can impede the performance at high quantities, and that Na, K, Ca, Ba, and Sr are generally detrimental to the performance but can be tolerated in small quantities (i.e., less than 1%, or ideally less than 0.1%). It is still further understood that Li+ions have a remarkable chemical affinity for Mn4+, which results in a rapid formation of a spinel phase when reacted at temperatures as low as 500 °C, and that Fe3+ions are highly stable in the spinel crystal structure. It can, therefore, be understood that if a mixture of an iron ore, a manganese ore, a lithium source such as Li2CO3, and a base such as Na2CO3 are mixed in the appropriate proportions and calcined, they will react to form a spinel phase (i.e., LiFeMnO4) that contains substantially all of the Li, Mn, Fe, Mg, Ti, Zn, V, Cr, Zr, Co, and Ni present in the mixture, and the other elements, including Al, Si, Ca, Na, and K, can form either soluble compounds that can be removed by washing with water, or insoluble compounds which can be removed by magnetic separation. It is further understood that Al can both enter the Spinel crystal structure and / or react with an alkali base to form a soluble compound (i.e., NaAlO2), and that Al is generally less reactive to alkali bases than Si. Therefore, without wishing to be bound by any theory, it can be still further understood that even in theAttorney Docket No.10046-611WO1 8386 MAN presence of an excess amount of an alkali base, some amount of Al impurities may be present in the Spinel phase, that in the presence of a deficient amount of an alkali base an appreciable amount of Al may be present in the Spinel phase while some ore substantially all of the Si may react to form soluble compounds, and that without providing an alkali base substantially all of the Al will be present in the spinel phase and substantially all of the Si will be present as insoluble compounds. More generally, it can therefore be understood that the amounts of Al and / or Si present in the LMFO precursor either in the Spinel phase, as soluble impurity phase(s), or as insoluble impurity phase(s), can be controlled by the amount of alkali base provided in the synthesis of the LMFO precursor. For example, if an excess of NaOH is added, then substantially all the Al and Si would be present in the form of soluble compounds, while if a deficient amount of NaOH is added, then small quantities of Al and / or Si may be present in the spinel precursor.

[0159] It can be appreciated that while high purity LiOH or Li2CO3 (i.e., > 99.9%) is typically used for cathode synthesis for LIBs, lower purity lithium sources (i.e. < 99%) that contain common impurities like Na, K, Mg, and Ca could be employed for LMFO spinel synthesis without detrimental effects. As a result, about half of the lithium required for LMFP synthesis could be provided in the form of low-purity chemicals during the synthesis of the spinel LMFO, which would reduce the raw material cost.

[0160] Furthermore, due to the presence of high-spin Fe3+: 3d5ions in both the octahedral and tetrahedral sites of the LMFO spinel structure, the spinel precursor is ferrimagnetic, so magnetic separation can be used to purify it from insoluble impurities if needed. Overall, it is believed that milling and heating a mixture of an iron ore, a manganese ore, a lithium source, and an alkali-containing base will form an LMFO spinel phase wherein the impurities included in the LMFO phase are beneficial to the electrochemical performance of LMFP and therefore act as dopants. The spinel phase of this precursor can be easily separated from soluble compounds containing detrimental impurities by washing and from insoluble compounds containing detrimental impurities by magnetic separation.

[0161] After optimizing the precursor synthesis parameters, LMFP was synthesized either from LMFO, NH4Mn0.5Fe0.5PO4•H2O, or separate oxide precursors via the two- step carbon coating and spray drying procedure. FIG.6A presents the XRD patternsAttorney Docket No.10046-611WO1 8386 MAN of all three LMFP samples. S-LMFP and P-LMFP are both phase pure, while O- LMFP shows impurity peaks at 43.5oand 62.4o, which can be indexed to metallic Fe. The reduction of Fe2O3 and MnO2 may occur at different rates during the synthesis of O-LMFP, leading to phase separation in the final product. Notably, there was no difference in milling procedures among the three samples. While it is possible that more aggressive milling conditions could eliminate this impurity, the absence of impurities in the LMFP synthesized from spinel LMFO emphasizes the advantage of an atomically mixed Mn / Fe precursor; the Mn / Fe distribution is entirely insensitive to milling conditions, which is beneficial for manufacturing scalability. The physical and electrochemical properties of S-LMFP and P-LMFP are compared throughout this work. The lattice parameters of both S-LMFP and P-LMFP are within ±0.01 Å for a, b, and c with Rwp values of 10%, indicating no differences in the bulk crystal structure. Additionally, S-LMFP and P-LMFP both have very similar BET surface area (~ 27 m2g-1) and carbon content (~ 3 wt%) and exhibit minimal electronic resistance within the porous electrode. (FIGs.6B-6D).

[0162] The main difference between S-LMFP and P-LMFP is in the primary particle size and morphology, as shown by SEM imaging (FIGs.7A-7I). Spray drying causes the primary particles to aggregate into porous, spherical secondary particles, which have a diameter of 3 – 15 μm for both samples (FIG.7A-7C). It is observed that S- LMFP and O-LMFP both have larger primary particles compared to P-LMFP (FIG. 7D-7F). Under the same milling conditions, it is assumed that LMFO, which is much harder than NH4Mn0.5Fe0.5PO4•H2O, would not be milled to as small of a particle size. It is likely that more aggressive milling conditions could further reduce the primary particle size of LMFP synthesized with LMFO. The internal morphology of the secondary particles was characterized with SEM after preparing cross sections with a focused ion beam. S-LMFP and O-LMFP both contain a much larger number of internal voids compared to P-LMFP (FIGs.7G-7I), which are likely caused by the formation of steam bubbles during the spray drying process. Tuning the spray-drying parameters, such as the solid loading of the dispersion and the inlet temperature, may be effective at reducing the internal voids within the secondary particles.

[0163] Despite the more porous appearance under SEM, S-LMFP has a significantly higher tap density of 1.2 g cm-3than P-LMFP (1.0 g cm-3), which indicates that theAttorney Docket No.10046-611WO1 8386 MAN primary particles within S-LMFP are much more densely aggregated than those in P- LMFP. Upon calendaring the electrodes with 95 wt% active material content, the maximum press density achieved before delamination of the electrode coating is much higher for S-LMFP (greater than 2.6 g cm-3) than for P-LMFP (about 2.2 g cm-3), which can be attributed to the higher packing density of primary particles. Surprisingly, the press density of S-LMFP is competitive with state-of-the-art LiFePO4 cathode materials. It is likely that the large internal voids within the S-LMFP secondary particles collapse during calendaring, so improvements in the spray drying process may improve the tap density of the powder but not the press density of the electrode.

[0164] The cycle life of all LMFP samples is excellent, showing little or no capacity loss after 100 cycles in half cells at a C / 5 rate (FIG.8A). O-LMFP has a poor electrochemical performance by comparison, achieving less than 130 mA h g-1at a C / 5 rate (FIG.9A). On a gravimetrical basis, the electrochemical performance of P- LMFP is superior to that of S-LMFP, offering both a higher discharge capacity and improved capacity retention at high rates (FIG.8B). The discharge capacity of P- LMFP is 153 and 149 mA h g-1at rates of, respectively, C / 10 and C / 3, compared to 147 and 141 mA h g-1for S-LMFP. The discharge rate performance is slightly better for P-LMFP, which retains 86.6% of the C / 10 rated capacity when discharged at a 5C rate, while S-LMFP retains 83.2%. From the discharge voltage profiles at various rates, it is evident that the reduced capacity and lower average voltage of both samples at higher discharge rates are mainly due to the kinetic limitations of Mn2+ / 3+redox (FIG.8C-8D). The inferior kinetics of Mn2+ / 3+redox can be generally attributed to solid-state Li+transport limitations.

[0165] Based on the Atlung Method for Intercalant Diffusion, the apparent Li+diffusion coefficient of LMFP with 50% Mn content was found to be an order of magnitude lower for Mn2+ / 3+redox than for Fe2+ / 3+redox. The diffusion limitations for Mn2+ / 3+redox manifest as increased voltage polarization and lower accessible capacity of the 4.0 V plateau at high rates. It appears that some additional capacity from Mn2+ / 3+redox is obtained between 3.7 to 3.5 V, where Fe2+ / 3redox becomes active and thus can improve the Li+diffusion kinetics. The kinetic limitations of Mn2+ / 3+redox are also evident at the C / 5 rate: S-LMFP achieves a charge capacity ofAttorney Docket No.10046-611WO1 8386 MAN 147 mA h g-1with 10 mA h g-1coming from the CV hold at 4.3 V, while P-LMFP achieves a first charge capacity of 152 mA h g-1with only 3 mA h g-1coming from the CV hold (FIG.9B). Compared to P-LMFP, there is a larger portion of the capacity from S-LMFP, which can only be accessed at low rates (i.e., < C / 10). Considering that both samples have the same composition and exhibit low electronic resistance, it is likely that this difference in diffusion kinetics is caused by the larger primary particle size of S-LMFP. More specifically, due to the wider particle size distribution of S-LMFP, severe diffusion limitations likely occur in the primary particle with a larger size (i.e.,> 200 nm), while those with a smaller size (i.e., < 100 nm), comparable to that of P-LMFP, likely will not have severe diffusion limitations.

[0166] While the electrochemical performance of LIB active materials is typically reported on a gravimetric basis, in most applications, such as electric vehicles, the volumetric energy density of the battery is much more important than the specific energy. The volumetric energy density is determined by the product of specific capacity, average discharge voltage, and electrode density. In practical electrode compositions with 95 wt% active material, P-LMFP can only be compacted to a maximum press density of 2.2 g cm-3before delamination of the electrode coating from the current collector, while S-LMFP can be compacted to 2.6 g cm-3. Notably, the press density of S-LMFP meets or exceeds that of state-of-the art LFP active materials, which typically have a press density of ~ 2.5 g cm-3. As a result, despite the lower specific capacity of S-LMFP, it can achieve a maximum energy density of 1,210 W h L-1on a cathode basis at a C / 5 rate, compared to 1,060 W h L-1for P- LMFP. Table 1 summarizes both the physical and electrochemical properties of both cathodes. However, the lower rate performance of S-LMFP compared to that of P- LMFP can reduce the energy density at higher rates. With lower electrode porosity at high press densities like that in S-LMFP, electrolyte transport limitations can significantly limit the rate performance. Accordingly, rate performance testing was conducted for both samples across a wide range of press densities to determine the optimal conditions for maximizing energy density.

[0167] Table 1. Physical and electrochemical properties of S-LMFP and P- LMFP. Discharge capacity, average discharge voltage, and volumetric discharge energy obtained at C / 5 rate.Attorney Docket No.10046-611WO1 8386 MAN Sample Tap Press Discharge Average Volumetric Density, Density, Capacity Discharge Discharge e)

[0168] For P-LMFP, with an active material loading of 1.0 mA h cm-2, there is essentially no difference in the rate performance between press densities of 1.81 to 2.15 g cm-3(FIG.10D). For S-LMFP with the same loading, the rate performance is similar between press densities of 2.32 to 2.39 g cm-3but decreases at a press density of 2.49 g cm-3or higher (FIG.10A). Since volumetric capacity is directly proportional to press density, S-LMFP greatly outperforms P-LMFP in volumetric capacity at low rates when capacity retention is high (FIG.10B). S-LMFP has about a 0.05 V lower average discharge voltage than P-LMFP, and both samples experience about a 0.4 V drop in average discharge voltage from a C / 10 to a 10C rate. Overall, the press density does not appreciably affect the average discharge voltage (FIG.10C). The electrode-level volumetric energy follows essentially the same trend as volumetric capacity (FIG.10E). At low rates (i.e., ≤ C / 3) where kinetic limitations are less severe, press density is clearly far more important than specific capacity or average discharge voltage in determining the energy density, and S- LMFP greatly outperforms P-LMFP. At intermediate rates (i.e., 1C), S-LMFP still outperforms P-LMFP in energy density, but only by a small margin. At high rates (i.e., ≥ 5C), both samples exhibit essentially the same maximum energy density.

[0169] Specifically, at a 10C rate, the energy density of S-LMFP electrodes with a press density of 2.39 g cm-3is equivalent to that of P-LMFP electrodes with a press density of 2.15 g cm-3, and S-LMFP electrodes with either a higher or lower press density exhibit inferior energy density. At high rates, electrolyte transport limitations within the porous electrode can significantly limit the rate performance like in S- LMFP above 2.5 g cm-3. These limitations will be exacerbated at higher electrode loadings of 3 – 4 mA h cm-2, which are typical of commercial LIB cells. The optimal press density of LMFP electrodes to maximize energy density will, therefore, dependAttorney Docket No.10046-611WO1 8386 MAN on the application requirements and many aspects of cell design, including electrode loading and electrolyte transport properties. The dependence of energy density on press density and discharge rate is summarized in FIG.10F. In electric vehicle applications where LMFP is most likely to be used, the continuous discharge rate typically does not exceed C / 3; in this case, it is assumed that S-LMFP would greatly outperform P-LMFP in usable energy density. More generally, it can be concluded that to achieve high energy density with LMFP cells, it may be necessary to sacrifice the specific capacity and / or average voltage of the cathode material in order to improve the press density of the electrode.

[0170] Of course, to achieve the maximum possible energy density, LMFP cathodes should ideally exhibit both high press density and discharge capacity enabled by excellent Mn2+ / 3+redox kinetics. To understand the extent to which the energy density can be improved by mitigating the kinetic limitations of Mn2+ / 3+redox, S- LMFP and P-LMFP half cells were tested at temperatures of 0 °C, 25 °C, and 55 °C (FIG.11). Upon raising the temperature from 25 °C to 55 °C, the capacity of S-LMFP increases from 145 to 155 mA h g-1at a C / 5 rate, while the capacity of P-LMFP increases from 151 to 159 mA h g-1(FIGs.11A, 11C). For both samples, this increase in capacity can be attributed to an improvement in the Mn2+ / 3+redox kinetics, as evidenced by the increased capacity from the 4.0 V plateau, as well as the larger peak intensity and decreased voltage hysteresis observed in the dQ / dV plots (FIG.11b, 11D). Notably, for S-LMFP, a long CV hold is not needed to achieve the full capacity at 55 °C, and compared to room temperature, the electrode-level energy density increases by about 7%, from 1,300 to 1,400 W h L-1. Conversely, upon lowering the temperature from 25 °C to 0 °C, the capacity of S-LMFP and P- LMFP decreases to, respectively, 102 and 127 mA h g-1. Likewise, this decrease in capacity can mainly be attributed to a worsening of the Mn2+ / 3+redox kinetics, which is more severe for S-LMFP than for P-LMFP due to the larger particle size.

[0171] However, the lower capacity from Fe2+ / 3+redox in both samples at 0 °C indicates that there is also a contribution from electrolyte transport limitations due to the lower conductivity of the electrolyte at low temperatures, and it can be more severe for S-LMFP due to lower electrode porosity. The temperature dependence of the Mn2+ / 3+redox kinetics presents both challenges and opportunities for theAttorney Docket No.10046-611WO1 8386 MAN development of LMFP cells. The low-temperature performance of LFP cells is generally poor due to electrolyte transport limitations, and that of LMFP cells will only be worsened by sluggish Mn2+ / 3+redox kinetics. Depending on the application requirements, the low-temperature performance of LMFP may become problematic and must be considered in the overall performance evaluation. While the high operating temperatures of 40 – 50 °C experienced during fast charging could help to overcome the kinetic limitations of LMFP, the high temperature lifetime of LMFP cells is much worse than LFP cells, possibly due to Mn2+dissolution induced by the disproportionation of Jann-Teller active Mn3+ions. Electrolyte design will also, therefore, play a critical role in improving the usable energy density of LMFP cells.

[0172] Conclusion

[0173] A scalable and wastewater-free synthesis process for high volumetric capacity LMFP cathodes has been developed based on a novel ternary transition-metal oxide precursor, the LiMnFeO4 spinel, which is synthesized with a facile, low-cost solid- state reaction. The LiMnFeO4 precursor ensures homogeneous mixing of Mn and Fe at the atomic scale while improving the packing density of primary particles compared to LMFP synthesized from an NH4Mn0.5Fe0.5PO4•H2O precursor (P- LMFP). The LMFP synthesized with LiMnFeO4 (S-LMFP) achieves a specific capacity of 145 mA h g-1at C / 5 rate in electrodes with 95 wt% active material content and an exceptional press density of up to 2.6 g cm-3. The S-LMFP offers a slightly lower specific capacity and average discharge voltage than the P-LMFP due to the kinetic limitations of Mn2+ / 3+redox arising from its larger primary particle size. Despite its lower specific energy, S-LMFP offers 15% higher electrode-level volumetric energy than P-LMFP due to its much higher electrode density. Rate performance testing of both materials with various electrode densities reveals that at low discharge rates (i.e., < 1C), which are typical of electric vehicle batteries, the electrode density is much more important in determining the energy density than the specific capacity and average discharge voltage. Accordingly, in order to realize high practical energy density in LMFP cells, it is necessary to synthesize LMFP cathodes, which can achieve comparable electrode density to state-of-the-art LFP (i.e., > 2.5 g cm-3). The synthesis of LMFP cathodes from spinel LiMnFeO4 is a promising route to improve the density of LMFP electrodes; however, additional optimization ofAttorney Docket No.10046-611WO1 8386 MAN composition, particle size, and synthesis conditions is needed to overcome the sluggish Mn2+ / 3+redox kinetics.

[0174] The devices, systems, and methods of the appended claims are not limited in scope by the specific devices, systems, and methods described herein, which are intended as illustrations of a few aspects of the claims. Any devices, systems, and functionally equivalent methods are intended to fall within the scope of the claims. Various modifications of the devices, systems, and methods, in addition to those shown and described herein, are intended to fall within the scope of the appended claims. Further, while only certain representative devices, systems, and method steps disclosed herein are specifically described, other combinations of the devices, systems, and method steps are also intended to fall within the scope of the appended claims, even if not specifically recited. Thus, a combination of steps, elements, components, or constituents may be explicitly mentioned herein or less; however, other combinations of steps, elements, components, and constituents are included, even though not explicitly stated.

[0175] Although several embodiments of the invention have been disclosed in the foregoing specification, it is understood by those skilled in the art that many modifications and other embodiments of the invention will come to mind to which the invention pertains, having the benefit of the teaching presented in the foregoing description and associated drawings. It is thus understood that the invention is not limited to the specific embodiments disclosed hereinabove and that many modifications and other embodiments are intended to be included within the scope of the appended claims. Moreover, although specific terms are employed herein, as well as in the claims which follow, they are used only in a generic and descriptive sense and not for the purposes of limiting the described invention or the claims which follow.

[0176] Unless defined otherwise, all technical and scientific terms used herein have the same meanings as commonly understood by one of skill in the art to which the disclosed invention belongs. Publications cited herein and the materials for which they are cited are specifically incorporated by reference.

[0177] The claims are not intended to include, and should not be interpreted to include, means-plus- or step-plus-function limitations unless such a limitation isAttorney Docket No.10046-611WO1 8386 MAN explicitly recited in a given claim using the phrase(s) “means for” or “step for,” respectively.

[0178] In view of the described processes and compositions, herein below are described certain more particularly described aspects of the inventions. These particularly recited aspects should not, however, be interpreted to have any limiting effect on any different claims containing different or more general teachings described herein or that the “particular” aspects are somehow limited in some way other than the inherent meanings of the language and formulas literally used therein. EXEMPLARY ASPECTS

[0179] In view of the described processes and compositions, herein below are described certain more particularly described aspects of the disclosures. These particularly recited aspects should not, however, be interpreted to have any limiting effect on any different claims containing different or more general teachings described herein, or that the “particular” aspects are somehow limited in some way other than the inherent meanings of the language and formulas literally used therein.

[0180] Example 1. A cathode material comprising: a structure comprising LiaMnxFeyDz(PO4)c, wherein the cathode material comprises at least two phases, wherein a first phase is an olivine phase, and a second phase, and wherein the olivine phase is present in an amount greater than 90 wt% based on the total weight of the at least two phases, wherein 1 ≤ a ≤ 1.2 wherein 0.4 ≤ x ≤ 0.8, wherein 0.2 ≤ y ≤ 0.6, wherein 1 ≤ c ≤ 1.1, wherein D comprises one or more cations different from Li+, Mn2+,and Fe2+, wherein D comprises at least Al3+and Si4+, and wherein at least an amount of Al3+and Si4+is present in the second phase; wherein z is a total amount of moles of D present and is 0.01 ≤ z ≤ 0.1 wherein x + y + z = 1; and wherein the cathode material exhibits an electrode press density of greater than 2.2 g cm-3; and an electrode volumetric density equal to or greater than 1200 Wh L-1.

[0181] Example 2. The cathode material of any one of the examples herein, particularly example 1, wherein the second phase further comprises lithium, phosphorous, and oxygen.Attorney Docket No.10046-611WO1 8386 MAN

[0182] Example 3. The cathode material of any one of the examples herein, particularly any one of example 1 or 2, wherein D further comprises Ni2+, Co2+, Zn2+, Mg2+, Cu2+, B3+, V3+, Cr3+, Ti4+, Zr4+, Nb5+, Ta5+, Mo6+, W6+, or a combination thereof.

[0183] Example 4. The cathode material of any one of the examples herein, particularly any one of examples 1-3, wherein LiaMnxFeyDz(PO4)c is formed from a precursor having a general formula Lia'Mnx'Fey'Mz'O4 and comprising one or more phases, wherein one or more phases is a spinel phase present in an amount of at least 95 wt% based on the total weight of all phases, wherein D comprises M, wherein 0.5 ≤ a' ≤ 1 wherein 0.8 ≤ x' ≤ 1.6, wherein 0.4 ≤ y' ≤ 1.2, wherein 0.01 <z' ≤ 0.2, and wherein a' + x' + y' + z' ≤ 3.

[0184] Example 5. The cathode of any one of the examples herein, particularly example 4, wherein M comprises Al3+and Si4+.

[0185] Example 6. The cathode material of any one of the examples herein, particularly any one of examples 4 or 5, wherein M further comprises Mg2+, Zn2+, Ni2+, Cu2+, B3+, Co3+, V3+, Cr3+, V4+, Ti4+, P5+, V5+, Zr4+, or a combination thereof.

[0186] Example 7. The cathode material of any one of the examples herein, particularly any one of examples 1-6, where D further comprises Na+, K+, and Ca2+in an amount of less than 25 mole%, or less than 10 mole%, or less than 5 mole%, of the total ions present in D.

[0187] Example 8. The cathode material of any one of the examples herein, particularly any one of examples 4-7, wherein M further comprises Na+, K+, and Ca2+in an amount of less than 25 mole%, or less than 10 mole%, or less than 5 mole% of the total ions present in M.

[0188] Example 9. The cathode material of any one of the examples herein, particularly any one of examples 1-8, wherein the LiaMnxFeyDz(PO4)c comprises a plurality of primary particles having an average size of 50 to 500 nm.

[0189] Example 10. The cathode material of any one of the examples herein, particularly any one of examples 1-9, further comprising an amount of carbon.

[0190] Example 11. The cathode material of any one of the examples herein, particularly example 10, wherein the amount of carbon is at least 1 wt% and up to 5 wt%.Attorney Docket No.10046-611WO1 8386 MAN

[0191] Example 12. The cathode material of any one of the examples herein, particularly any one of examples 10 or 11, wherein the carbon is disposed as a coating on the primary particles, wherein the coating has a thickness of less than 3 nm.

[0192] Example 13. The cathode material of any one of the examples herein, particularly any one of examples 9-12, wherein the plurality of primary particles form agglomerates having a substantially spherical shape and an average diameter of 1- 25 microns.

[0193] Example 14. The cathode material of any one of the examples herein, particularly any one of examples 1-13, wherein the Mn and Fe are uniformly distributed within the olivine phase of LiaMnxFeyDz(PO4)c.

[0194] Example 15. The cathode material of any one of the examples herein, particularly any one of examples 1-14, wherein the electrode press density is at least 2.4 g / cm3to 2.6 g / cm3.

[0195] Example 16. A battery comprising a cathode material of any one of the examples herein, particularly any one of examples 1-15.

[0196] Example 17. The battery of any one of the examples herein, particularly example 16, wherein the battery further comprises an anode electrode and an electrolyte and is a secondary battery.

[0197] Example 18. The battery of any one of the examples herein, particularly example 17, wherein the anode electrode comprises Li metal, Li metal alloy, lithium titanium oxide, silicon alloy, silicon tin alloy, carbon, graphite, carbonaceous anodes, tin, aluminum, or any combination thereof.

[0198] Example 19. The battery of any one of the examples herein, particularly example 17, wherein the anode electrode is a current collector configured to be plated with Li during a plating cycle of the battery.

[0199] Example 20. The battery of any one of the examples herein, particularly any one of examples 16-19, wherein the battery operates at a voltage of 2.0 V to 4.4 V, or 2.5V to 4.3 V.Attorney Docket No.10046-611WO1 8386 MAN

[0200] Example 21. The battery of any one of the examples herein, particularly any one of examples 16-20, wherein the electrolyte is a liquid electrolyte comprising a salt and a solvent.

[0201] Example 22. The battery of any one of the examples herein, particularly example 21, wherein the salt comprises one or more of lithium fluorophosphate (LiPF6), lithium fluoroborate (LiBF4), lithium tetraphenylborate (LiBPh4), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium (fluorosulfonyl)(trifluoromethanesulfonyl)imide (LiFTFSI), lithium perchlorate (LiClO4), lithium nitrate (LiNO3), lithium 4,5-dicyano-2-(trifluoromethyl)imidazole (LiTDI), lithium 4,5-dicyano-2-(pentafluoromethyl)imidazole (LiPDI), and lithium difluorooxalato borate (LiDFOB), or any combination thereof.

[0202] Example 23. The battery of any one of the examples herein, particularly any one of examples 21 or 22, wherein the solvent comprises one or more of ethylene carbonate (EC), 1,2-dimethoxyethane (DME), propylene carbonate (PC), dimethyl carbonate (DMC), diethyl carbonate (DEC), 1,2-dimethoxyethane (DME), fluoroethylene carbonate (FEC), tetrahydrofuran (THF), diethylene glycol dimethyl ether (diglyme), triethylene glycol dimethyl ether (TDEM), tetraethylene glycol dimethyl ether (TEGDME), and vinylene carbonate (VC), Bis(2,2,2-trifluoroethyl) ether (BTFE), 1,1,2,2-tetrafluoroethyl 2,2,3,3-tetrafluoropropylether (TTE), tris(2,2,2- trilfuoroethyl) orthoformate (TFEO), trimethylphosphate (TMP), triethylphosphate (TEP), methyl acetate, propionate, butyrate, or any combination hereof.

[0203] Example 24. The battery of any one of the examples herein, particularly any one of examples 21-23, wherein the salt is present in an amount of 0.01 M to 3 M.

[0204] Example 25. The battery of any one of the examples herein, particularly any one of examples 16-20, wherein the electrolyte is a solid electrolyte.

[0205] Example 26. The secondary battery of any one of the examples herein, particularly any one of examples 16-25, wherein the battery exhibits a capacity retention of at least 75% over at least 200 cycles.

[0206] Example 27. The secondary battery of any one of the examples herein, particularly any one of examples 16-26, wherein the battery exhibits a capacity retention of at least 75% over at least 500 cycles.Attorney Docket No.10046-611WO1 8386 MAN

[0207] Example 28. The secondary battery of any one of the examples herein, particularly any one of examples 16-27, wherein the battery exhibits coulombic efficiency of greater than 95%.

[0208] Example 29. The secondary battery of any one of the examples herein, particularly any one of examples 16-28, wherein the battery is capable of operating in a temperature range of -20 °C to 60 °C.

[0209] Example 30. A method of making the cathode material of any one of the examples herein, particularly any one of examples 1-20, wherein the cathode material is formed from (a) a mixture comprising: (i) a precursor having a general formula Lia'Mnx'Fey'Mz'O4 and comprising one or more phases, wherein one or more phases is a spinel phase present in an amount of at least 95 wt % based on the total weight of all phases; (ii) a phosphorous source; (iii) a lithium source; and (iv) a carbon source; (b) forming a plurality of particles; and (c) heating the plurality of particles to form the structure comprising LiaMnxFeyDz(PO4)c.

[0210] Example 31. The method of any one of the examples herein, particularly example 30, wherein the mixture further comprises water.

[0211] Example 32. The method of any one of the examples herein, particularly example 31, wherein the method further comprises homogeneously mixing and ball milling the mixture to form a slurry.

[0212] Example 33. The method of any one of the examples herein, particularly example 32, wherein the plurality of particles are obtained by spray drying the slurry.

[0213] Example 34. The method of any one of the examples herein, particularly any one of examples 30-33, wherein the heating is performed at a temperature of 550- 800 °C.

[0214] Example 35. The method of any one of the examples herein, particularly any one of examples 30-34, wherein the heating is performed under an inert atmosphere.

[0215] Example 36. The method of any one of the examples herein, particularly any one of examples 30-35, wherein the heating is performed for 0.5 to 4 hours.Attorney Docket No.10046-611WO1 8386 MAN

[0216] Example 37. The method of any one of the examples herein, particularly any one of examples 30-36, wherein the phosphorous source comprises a phosphoric acid, an organic or inorganic salt of phosphoric acid, or any combination thereof.

[0217] Example 38. The method of any one of the examples herein, particularly any one of examples 30-37, wherein Li source comprises lithium hydroxide, lithium carbonate, another organic and / or inorganic lithium salt, or a combination thereof.

[0218] Example 39. The method of any one of the examples herein, particularly any one of examples 30-38, wherein the carbon source comprises a mixture of at least one sugar and / or carboxylic acid compound and at least one polymer.

[0219] Example 40. The method of example 39, wherein the at least sugar comprises dextrose, sucrose, lactose, maltodextrin, cyclodextrin, dextrin, starch, or a combination thereof.

[0220] Example 41. The method of any one of the examples herein, particularly any one of examples 39 or 40, wherein the carboxylic acid compound comprises citric acid, ascorbic acid, oxalic acid, or a combination thereof.

[0221] Example 42. The method of any one of the examples herein, particularly any one of examples 38-41, wherein the polymer comprises polyethylene glycol, polyethylene oxide, polyvinyl alcohol, polyvinyl pyrrolidone, polyamide, polyimide, sodium carboxymethylcellulose, hydroxyethyl cellulose, hydroxymethyl cellulose, or any combination thereof.

[0222] Example 43. The method of any one of the examples herein, particularly any one of examples 30-42, wherein the mixture further comprises one or more processing aids.

[0223] Example 44. The method of any one of the examples herein, particularly any one of examples 30-43, wherein the precursor having a general formula Lia'Mnx'Fey'Mz'O4 comprising one or more phases, wherein one or more phases is a spinel phase present in an amount of at least 95 wt% based on a total weight of all phases is formed by: (a) forming a mixture comprising: (i) an iron source (ii) a manganese source, and (iii) a lithium source; (b) heating the mixture to a temperature of 800 to above 1000 °C to form the precursor.Attorney Docket No.10046-611WO1 8386 MAN

[0224] Example 45. The method of any one of the examples herein, particularly example 44, wherein the iron source, manganese source, lithium source, and / or a combination thereof have a purity of greater than 98%.

[0225] Example 46. The method of any one of the examples herein, particularly example 44, wherein the iron source, manganese source, lithium source, and / or a combination thereof have a purity of less than 98%.

[0226] Example 47. The method of any one of the examples herein, particularly example 46, wherein the iron source is an iron oxide, an iron ore, a concentrated iron ore, iron metal, an iron alloy, or a combination thereof.

[0227] Example 48. The method of any one of the examples herein, particularly any one of examples 46-47, wherein the manganese source is a manganese oxide, a manganese ore, a concentrated manganese ore, manganese metal, a manganese alloy, or a combination thereof.

[0228] Example 49. The method of any one of the examples herein, particularly any one of examples 46-48, wherein the lithium source comprises a lithium brine, a concentrated lithium brine, a precipitate of a lithium brine, a lithium ore, a concentrated lithium ore, another source of lithium with a purity of less than 99%, or a combination thereof.

[0229] Example 50. The method of any one of the examples herein, particularly any one of examples 44-49, wherein the mixture further comprises an alkali base.

[0230] Example 51. The method of any one of the examples herein, particularly any one of examples 44-50, wherein after the heating step, the precursor comprises at least one phase comprising soluble impurities.

[0231] Example 52. The method of any one of the examples herein, particularly any one of examples 44-51, wherein after the heating step, the precursor comprises at least one phase comprising insoluble impurities.

[0232] Example 53. The method of any one of the examples herein, particularly any one of examples 51-52, wherein a portion of the soluble impurities is removed by dissolving the impurities in water.Attorney Docket No.10046-611WO1 8386 MAN

[0233] Example 54. The method of any one of the examples herein, particularly any one of examples 52-53, wherein a portion of the insoluble impurities is removed by a magnetic separation.

[0234] Example 55. The method of any one of the examples herein, particularly any one of examples 44-54, wherein M comprises Al3+and Si4+.

[0235] Example 56. The method of any one of the examples herein, particularly any one of examples 44-55, wherein the mixture further comprises a source of M that is different from Mn and Fe.Attorney Docket No.10046-611WO1 8386 MAN REFERENCES 1. C. Curry, Bloomberg New Energy Finance, 2017, 5 (4-6), 43. 2. B. Nykvist and M. Nilsson, Nature Climate Change, 2015, 5, 329-332. 3. B. E. Murdock, K.E. Toghill, and N. Tapia-Ruiz, Advanced Energy Materials, 2021, 11, 39. 4. C. Earl, I. H. Shah, S. Cook, and C. R. Cheeseman, Sustainability, 2022, 14 (7), 4124. 5. S. Lee and A. Manthiram, ACS Energy Letters, 2022, 7 (9), 2058-3063. 6. LME Cobalt Official Prices, London Metals Exchange, https: / / www.lme.com / en / metals / ev / lme-cobalt, (accessed 2024-04-10). 7. LME Nickel Official Prices, London Metals Exchange, https: / / www.lme.com / en / metals / non-ferrous / lme-nickel, (accessed 2024-04-10). 8. A. K. Padhi, K. S. Nanjundaswamy, and J. B. Goodenough, J. Electrochem. Soc., 1997, 144, 1188. 9. F. M. N. U. Khan, M. G. Rasul, A. S. M. Sayem, and N. K. Mandal, Journal of Energy Storage, 2023, 71, 108033. 10. K. W. Knehr, J. J. Kubal, P. A. Nelson, and S. Ahmed, 2022, ANL / CSE-22 / 1. 11. M. Fleischer, Journal of Chemical Education, 1954, 31 (9), 446. 12. A. Yamada, S. C. Chung, and K. Hinokuma, J. Electrochem. Soc., 2001, 148, A224. 13. K. Zaghib et al., Journal of Power Sources, 2012, 219, 36-44. 14. T. Murallganth and A. Manthiram, J. Phys. Chem. C, 2010, 114, 15530-15540. 15. D. B. Ravnsbæk, K. Xiang, W. Xing, O. J. Borkiewicz, K. M. Wiaderek, P. Gionet, K. W. Chapman, P. J. Chupas, and Y. M. Chiang, Nano Lett., 2014, 14, 1484 – 1491. 16. S. Wia, J. Park, S. Lee, J. Kim, B. Gil, A. J. Yun, Y. E. Sung, B. Park, and C. Kim, Nano Energy, 2017, 39, 371-379. 17. E. Lyle, R. Vaeli, M. Cormier, and M. Metzger, J. Electrochem. Soc., 2022, 169, 060527. 18. D. B. Ravnsbæk, K. Xiang, W. Xing, O. J. Borkiewicz, K. M. Wiaderek, P. Gionet, K. W. Chapman, P. J. Chupas, M. Ting, and Y. M. Chiang. Nano Lett.2016, 16 (4), 2375–2380. 19. A. Yamada, Y. Takei, H. Koizumi, N. Sonoyama, R. Kanno, K. Itoh, M. Yonemura, and T. Kamiyama, Chemistry of Materials, 2006, 18 (3), 804-813. 20. Z. X. Nie, C. Y. Ouyang, J. Z. Chen, Z. Y. Zhong, Y. L. Dua, D. S. Liu, S. Q. Shi, and M. S. Lei, Solid State Communications, 2010, 150, 40–44. 21. W. Liu, P. Gao, Y. Mi, J. Chen, H. Zhou, and X. Zhang, J. Mater. Chem. A, 2013, 1, 2411. 22. L. Wu, S. H. Zhong, J. Q. Liu, F. Lv, and K. Wan, Materials Letters, 2012, 89, 32- 35. 23. J.-K. Kim, CrystEngComm, 2014, 16, 2818. 24. C. T. Hsieh, I. L. Chen, W. Y. Chen, and J. P. Wang, Electrochimica Acta, 2012, 83, 202-208. 25. W. C. Chien, K. N. Liu, S. C. Chang, and C. C. Yang, Thin Solid Films, 2018, 660, 931-937. 26. I. Seo, B. Senthilkumar, K. H. Kim, J. K. Kim, Y. Kim, and J. H. Ahn, Journal of Power Sources, 2016, 320, 59-67.Attorney Docket No.10046-611WO1 8386 MAN 27. J. Li, Y. Wang, J. Wu, H. Zhao, H. Wu, Y. Zhang, and H. Liu, Chemelectrochem, 2017, 4, 175-182. 28. J. Li, M. Qiang, Y. Wang, J. Wu, H. Zhao, and H. Liu, J. Mater. Chem. A, 2017, 5, 7952-7960. 29. S. M. Oh, S. T. Myung, Y. S. Choi, K. H. Oh and Y. K. Sun, J. Mater. Chem., 2011, 21, 19363-19374. 30. J. F. Blais, S. Dufresne, and G. Mercier, Journal of Water Science, 1999, 12 (4), 687-711. 31. P. Y. Yang, S. P. Ju, H. S. Hsieh, and J. S. Lin, RSC Adv., 2017, 7, 55044- 55050. 32. L. Gao, Z. Liu, Z. Yang, L. Cao, C. Feng, M. Chu, and J. Tang, Applied Surface Science, 2020, 508, 145292. 33. J. D. Hem, Geochimica et Cosochimica Acta, 1981, 45, 1369-1374. 34. M. J. O'Neil, (ed.) The Merck Index - An Encyclopedia of Chemicals, Drugs, and Biologicals. Merck and Co., Inc., 2006, 88. 35. H. J. Van Hook and M. L. Keith, The American Mineralogist, 1958, 43, 69-83. 36. T. Liu et. al., Nature Communications, 2019, 10, 4721. 37. M. Gracia, J. F. Marco, J. R. Gancedo, J. Ortiz, R. Pastene, and J. L. Gautier, J. Phys. Chem. C, 2010, 114 (29), 12792–12799. 38. D. M. Tinsley and J. H. Sharp, Journal of Thermal Analysis, 1971, 3, 43-48. 39. Q. Fradet, M. Kurnatowska, and U. Riedel, Thermochimica Acta, 2023, 726, 179552. 40. J. Darga, J. Lamb, and A. Manthiram, Energy Technology, 2020, 8 (12), 2000723. 41. W. Li, H. Gu, H. Yang, Q. Li, X. Li, Y. Wang, and G. Liang, J. Electrochem. Soc., 2024, 171, 02054. 42. C. Delmas, M. Maccario, L. Croguennec, F. Le Cras, and F. Weill, Nature Materials, 2008, 7, 665-671. 43. R. Dominko, M. Bele, M. Gaberscek, M. Remskar, D. Hanzel, S. Pejovnik, and J. Jamnik, J. Electrochem. Soc, 152, A607. 44. Z. X. Chia, W. Zhang, F. Q. Cheng, J. T. Chen, A. M. Cao, and L. J. Wan, RSC Adv., 2014, 4, 7795-7798.

Claims

Attorney Docket No.10046-611WO1 8386 MAN CLAIMS 1. A cathode material comprising: a structure comprising LiaMnxFeyDz(PO4)c, wherein the cathode material comprises at least two phases, wherein a first phase is an olivine phase, and a second phase, and wherein the olivine phase is present in an amount greater than 90 wt% based on the total weight of the at least two phases, wherein 1 ≤ a ≤ 1.2 wherein 0.4 ≤ x ≤ 0.8, wherein 0.2 ≤ y ≤ 0.6, wherein 1 ≤ c ≤ 1.1, wherein D comprises one or more cations different from Li+, Mn2+,and Fe2+, wherein D comprises at least Al3+and Si4+, and wherein at least an amount of Al3+and Si+4is present in the second phase; wherein z is a total amount of moles of D present and is 0.01 ≤ z ≤ 0.1 wherein x + y + z = 1; and wherein the cathode material exhibits an electrode press density of greater than 2.2 g cm-3; and an electrode volumetric density equal to or greater than 1200 Wh L-1.

2. The cathode material of claim 1, wherein the second phase further comprises lithium, phosphorous, and / or oxygen.Attorney Docket No.10046-611WO1 8386 MAN 3. The cathode material of claim 1 or 2, wherein D further comprises Ni2+, Co2+, Zn2+, Mg2+, Cu2+, B3+, V3+, Cr3+, Ti4+, Zr4+, Nb5+, Ta5+, Mo6+, W6+, or a combination thereof.

4. The cathode material of any one of claims 1-3, wherein LiaMnxFeyDz(PO4)c is formed from a precursor having a general formula Lia’Mnx’Fey’Mz’O4 and comprising one or more phases, wherein one or more phases is a spinel phase present in an amount of at least 95 wt% based on the total weight of all phases, wherein D comprises M, wherein 0.50 ≤ a’ ≤ 1.00 wherein 0.80 ≤ x’ ≤ 1.60, wherein 0.40 ≤ y’ ≤ 1.20, wherein 0.01 <z’ ≤ 0.20, and wherein a’ + x’ + y’ + z’ ≤ 3.

5. The cathode of claim 4, wherein M comprises Al3+and Si4+.

6. The cathode material of claim 4, wherein M further comprises Mg2+, Zn2+, Ni2+, Cu2+, B3+, Co3+, V3+, Cr3+, V4+, Ti4+, P5+, Zr4+, V5+, or a combination thereof.

7. The cathode material of any one of claims 1-6, where D further comprises Na+, K+, Ca2+, Sr2+, and Ba2+in an amount of less than 25 mole%, or less than 10 mole%, or less than 5 mole%, or less than 3 mole%, or less than 1 mole% of the total ions present in D.

8. The cathode material of any one of claims 4-7, wherein M further comprises Na+, K+, Ca2+, Sr2+, and Ba2+in an amount of less than 25 mole%, or less than 10 mole%, or less than 5 mole%, or less than 3 mole%, or less than 1 mole% of the total ions present in M.

9. The cathode material of any one of claims 1-8, wherein the LiaMnxFeyDz(PO4)c comprises a plurality of primary particles having an average size of 50 to 500 nm and / or wherein the plurality of primary particles form agglomerates having a substantially spherical shape and an average diameter of 1-25 microns.Attorney Docket No.10046-611WO1 8386 MAN 10. The cathode material of any one of claims 1-9, further comprising at least 1 wt% and up to 5 wt% of carbon.

11. The cathode material of claim 10, wherein the carbon is disposed as a coating on the primary particles, wherein the coating has a thickness of less than 3 nm.

12. A battery comprising a cathode material of any one of claims 1-11, wherein the battery further comprises an anode electrode and an electrolyte and is a secondary battery, and wherein the battery operates at a voltage of 2.0 V to 4.4 V, or 2.5V to 4.3 V.

13. The battery of claim 12, wherein the anode electrode comprises Li metal, Li metal alloy, lithium titanium oxide, silicon alloy, silicon tin alloy, carbon, graphite, carbonaceous anodes, tin, aluminum, or any combination thereof and / or wherein the anode electrode is a current collector configured to be plated with Li during a plating cycle of the battery.

14. The battery of any one of claims 12-13, wherein the electrolyte is a liquid electrolyte comprising a salt and a solvent, and / or wherein the electrolyte is a solid electrolyte.

15. The secondary battery of any one of claims 12-14, wherein the battery exhibits a capacity retention of at least 75% over at least 200 cycles, and / or wherein the battery exhibits coulombic efficiency of greater than 95%, and / or wherein the battery is capable of operating in a temperature range of -20 °C to 60 °C.

16. A method of making the cathode material of any one of claims 1-11, wherein the cathode material is formed from a) a mixture comprising: i) a precursor having a general formula Lia’Mnx’Fey’Mz’O4 and comprising one or more phases, wherein one or more phases is a spinel phase present in an amount of at least 95 wt% % based on the total weight of all phases; ii) a phosphorous source;Attorney Docket No.10046-611WO1 8386 MAN iii) a lithium source; and iv) a carbon source; b) forming a plurality of particles; and c) heating the plurality of particles to form the structure comprising LiaMnxFeyDz(PO4)c.

17. The method of claim 16, wherein the heating is performed at a temperature of 550-800 °C, and / or wherein the heating is performed under an inert atmosphere and / or wherein the heating is performed for 0.5 to 4 hours.

18. The method of any one of claims 16-17, wherein: the phosphorous source comprises a phosphoric acid, an organic or inorganic salt of phosphoric acid, or any combination thereof, and / or the Li source comprises lithium hydroxide, lithium carbonate, another organic and / or inorganic lithium salt, or a combination thereof; and / or the carbon source comprises a mixture of at least one sugar and / or carboxylic acid compound and at least one polymer.

19. The method of claim 18, wherein the at least sugar comprises dextrose, sucrose, lactose, maltodextrin, cyclodextrin, dextrin, starch, or a combination thereof, and / or wherein the carboxylic acid compound comprises citric acid, ascorbic acid, oxalic acid, or a combination thereof; and / or wherein the polymer comprises polyethylene glycol, polyethylene oxide, polyvinyl alcohol, polyvinyl pyrrolidone, polyamide, polyimide, sodium carboxymethylcellulose, hydroxyethyl cellulose, hydroxymethyl cellulose, or any combination thereof.

20. The method of any one of claims 16-19, wherein the precursor has a general formula Lia’Mnx’Fey’Mz’O4 comprising one or more phases, wherein one or more phases is a spinel phase present in an amount of at least 95 wt% based on the total weight of all phases, is formed by: a) forming a mixture comprising:Attorney Docket No.10046-611WO1 8386 MAN i) an iron source ii) a manganese source, andiii) a lithium source; and b) heating the mixture to a temperature of 800 to above 1000 °C to form the precursor.

21. The method of claim 20, wherein the iron source, manganese source, lithium source, and / or a combination thereof have a purity of greater than 98%, or wherein the iron source, manganese source, lithium source, and / or a combination thereof have a purity of less than 98%; and / or wherein the iron source is an iron oxide, an iron ore, a concentrated iron ore, iron metal, and iron alloy, or a combination thereof; and / or wherein the manganese source is a manganese oxide, a manganese ore, a concentrated manganese ore, manganese metal, a manganese alloy, or a combination thereof; and / or wherein the lithium source comprises a lithium brine, a concentrated lithium brine, a precipitate of a lithium brine, a lithium ore, a concentrated lithium ore, another source of lithium with a purity of less than 99%, or a combination thereof.

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