Substoichiometric lithium transition metal orthoborates as li-ion battery cathodes

Abstract

The present technology provides new and improved Li transition metal orthoborates comprising a sum of metal elements other than Li that is less than one when normalized to the stoichiometry of boron.

Description

Docket No. 113544-856296 PCT APPLICATION SUBSTOICHIOMETRIC LITHIUM TRANSITION METAL ORTHOBORATES AS LI- ION BATTERY CATHODES CROSS REFERENCE

[0001] The present patent application claims the benefit of priority to a Provisional Patent Application Serial No. 63 / 688,581, entitled “Substoichiometric Lithium Transition Metal Orthoborates As Li-ion Battery Cathodes,” filed on August 29, 2024, which is incorporated herein by reference in its entirety. TECHNICAL FIELD

[0002] Embodiments of the present invention relate to cathode materials useful in lithium-ion batteries. More specifically, embodiments of the present invention include new and improved Li transition metal orthoborates comprising a sum of metal elements other than Li that is less than one but greater than 0.7 when normalized to the stoichiometry of boron. BACKGROUND

[0003] Batteries are an essential part of many devices from power tools to home power systems to electric and hybrid cars, among many other applications. Lithium-ion batteries have been widely adopted as the most promising portable energy source in electronic devices because of their high working voltage, high energy density, and good cyclic performance. Lithium-ion batteries are used in electric vehicles and hybrid electric vehicles.

[0004] Lithium Transition Metal Orthoborates (e.g. LiMBO3, where M is typically a transition metal such as Mn, Fe, Mg, V, Co, Ni, Zn, Ca, Na, Al, Cr, or Cu) are attractive cathode materials for lithium-ion batteries for two main reasons. First, their covalently bonded anions contribute to operational stability by effectively suppressing oxygen loss. Second, they exhibit high theoretical gravimetric capacities of approximately 220 mAh / g. In comparison, the theoretical gravimetric capacity of conventional lithium iron phosphate (LFP) is approximately 170 mAh / g.

[0005] While Lithium Transition Metal Orthoborates are attractive cathode materials, their electrochemical performance is generally poor. 1 105690391.2Docket No. 113544-856296 PCT APPLICATION

[0006] Accordingly, there remains a need in the art for a solution to at least one of the aforementioned problems. BRIEF SUMMARY

[0007] Disclosed in the present application are Li-containing orthoborate materials having the formula Li1+xM1-xBO3. M comprises one or more transition metals; wherein 0 < x < 0.3, and wherein the Li-containing orthoborate material has a specific capacity greater than a Li containing orthoborate material having the formula LiMBO3.

[0008] In an embodiment, a sum of metal elements other than Li that is less than one but greater than 0.7 when normalized to the stoichiometry of boron.

[0009] In an aspect, a disclosed Li-containing orthoborate material may have a majority phase by X-ray diffraction analysis that may be described by the C2 / c monoclinic space group #15.

[0010] In an aspect, a disclosed Li-containing orthoborate may have a majority phase by X- ray diffraction analysis that may be described by the P6^hexagonal space group #174.

[0011] In an aspect, the M may be at least one of Mn, Fe, Mg, V, Co, Ni, Zn, Ca, Na, Al, Cr, or Cu. In another aspect, the M may be at least one of Mn, Fe, Mg and combinations thereof.

[0012] In an aspect, M consists of the combination of Mn and Fe in a Mn:Fe molar ratio ranging from about 1:1 to about 9:1. In another aspect, M consists of the combination of Mn and Fe in a Mn:Fe molar ratio ranging from about 1.5:1 to about 4:1. In yet another aspect, M consists of the combination of Mn and Fe in a Mn:Fe molar ratio of about 3:1.

[0013] In an aspect, the Li-containing orthoborate material comprises a stoichiometry of Li1.04Mn0.96BO3. In another aspect, the Li-containing orthoborate material comprises a stoichiometry of Li1.08Mn0.92BO3. In yet another aspect, the Li-containing orthoborate material comprises a stoichiometry of Li1.04Mn0.72Fe0.24BO3. In another aspect, the Li-containing orthoborate material comprises a stoichiometry of Li1.08Mn0.69Fe0.23BO3.

[0014] In a different aspect, the chemical formula of the Li-containing orthoborate material may be written as Li1M1-xBO3, wherein M may be one or more metal species not limited to the transition metals.

[0015] In an aspect, the Li-containing orthoborate material comprises a stoichiometry of LiMn0.95BO3. In another aspect, the Li-containing orthoborate material comprises a stoichiometry of LiMn0.90BO3. 2 105690391.2Docket No. 113544-856296 PCT APPLICATION

[0016] These and other objects, features, and advantages of the present invention will become more readily apparent from the attached drawings and the detailed description of the preferred embodiments which follow and may be attained by means of the instrumentalities and combinations particularly pointed out in the appended claim(s). BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0017] The preferred embodiments of the invention will hereinafter be described in conjunction with the appended drawings, which are incorporated into and form a part of the specification and together with the description, are provided to illustrate and not to limit the invention, where like designations denote like elements, and in which:

[0018] FIG. 1 shows the XRD pattern of LiMnBO3vs Li1.08Mn0.92BO3;

[0019] FIG. 2 shows the XRD pattern of LiMnBO3 vs LiMn0.9BO3;

[0020] FIG. 3 shows the XRD pattern of LiMn0.75Fe0.25BO3 vs Li1.08Mn0.69Fe0.23BO3;

[0021] FIG. 4 shows the electrochemical behavior under the ‘GITT Protocol’ of a standard LiMnBO3 compound together with that of a substoichiometric lithium transition metal orthoborate with composition Li1.04Mn0.96BO3; and

[0022] FIG. 5 shows the results from subjecting LiMn0.75Fe0.25BO3, Li1.04Mn0.72Fe0.24BO3, and Li1.08Mn0.69Fe0.23BO3to the ‘GITT Protocol’. DETAILED DESCRIPTION

[0023] Embodiments of the invention describe new and improved lithium transition metal orthoborates, which can be used as positive electrodes in lithium-ion batteries. More specifically, embodiments of the present invention include new and improved Li transition metal orthoborates comprising a sum of metal elements other than Li that is less than one but greater than 0.7 when normalized to the stoichiometry of boron. The stoichiometry of the novel materials in the embodiments of the present invention involve a sum of all metal elements other than Li of less than 1 but greater than 0.7 per formula unit. For example, the Li-containing orthoborate material may have the chemical formula Li1+xM1-xBO3or Li1M1-xBO3,wherein M can be one or more metal species not limited to the transition metals, and 0 < x < 0.3. This alternative stoichiometry improves the electrochemical performance of the disclosed Li-containing orthoborate materials. 3 105690391.2Docket No. 113544-856296 PCT APPLICATION

[0024] The detailed description set forth below is intended as a description of various configurations of the subject technology and is not intended to represent the only configurations in which the subject technology can be practiced. The appended drawings are incorporated herein and constitute a part of the detailed description. The detailed description includes specific details to provide a more thorough understanding of the subject technology. However, it will be clear and apparent that the subject technology is not limited to the specific details set forth herein and may be practiced without these details. In some instances, structures and components are shown in block diagram form to avoid obscuring the concepts of the subject technology.

[0025] The following detailed description refers to the accompanying drawings. Wherever possible, the same reference numbers are used in the drawings and the following description to refer to the same or similar elements. While many embodiments of the disclosure may be described, modifications, adaptations, and other implementations are possible. For example, substitutions, additions, or modifications may be made to the elements illustrated in the drawings, and the methods described herein may be modified by substituting, reordering, or adding stages to the disclosed methods. The present disclosure contains headers. It should be understood that these headers are used as references and are not to be construed as limiting upon the subjected matter disclosed under the header.

[0026] Embodiments of the invention describe new and improved lithium transition metal orthoborates, which can be used as positive electrodes in lithium-ion batteries. A typical lithium transition metal orthoborate contains one Li site, one transition metal site, and one boron site. Therefore, a typical lithium transition metal orthoborate will include a sum of all metal elements other than Li equal to 1 per formula unit. In contrast, the stoichiometry of the novel materials in the embodiments of the present invention involve a sum of all metal elements other than Li of less than 1 but greater than 0.7 per formula unit. As one formula unit contains one boron atom, the sum of metal elements other than Li is less than one when normalized to the quantity of boron.

[0027] For example, the Li-containing orthoborate material may have the chemical formula Li1+xM1-xBO3or Li1M1-xBO3, wherein M can be one or more metal species not limited to the transition metals, and 0 < x < 0.3. In the formula, x is < 1.0, x is < 0.9, x is < 0.8, x is < 0.7, x is < 0.6, x is < 0.5, x is < 0.4, or x is < 0.3 or x is < 0.2, or x is < 0.1, or x is < 0.05. In addition, x is ≥ 0, x is ≥ 0.01, x is ≥ 0.05, x is ≥ 0.1, x is ≥ 0.3, or x is ≥ 0.5 or x is ≥ 0.8. In an embodiment, in the formula Li1+xM1-xBO3, x is 0 ≤ x < 0.3. 4 105690391.2Docket No. 113544-856296 PCT APPLICATION

[0028] The Li-containing orthoborate material may include an additional carbon source, wherein the carbon source is added in an amount that does not alter the stoichiometry of the Li- containing orthoborate material. In particular, the carbon source includes a carbon-containing compound selected from an aromatic hydrocarbon compound including an alcohol, an acid, or a ketone. The aromatic hydrocarbon compound may include toluene, p-xylene, asphalt, or paraffin oil. Finally, a gas containing carbon atom may be utilized as a carbon-containing compound. The gas containing compound may include ethylene, methane, acetylene, carbon monoxide or the like.

[0029] The carbon-containing compound may be ascorbic acid, malic acid, tartaric acid, succinic acid, fumaric acid, citric acid, oxalic acid, gluconic acid, or lauric acid. Further, the carbon-containing compound may include carbon nanotubes, graphene, graphite, or carbon black.

[0030] Another source of the carbon-containing compound includes sugars including but not limited to sucrose, glucose, dextrose, fructose, lactose, or maltodextrin. In an embodiment, the carbon-containing compound may include organic polymers comprising polyethylene, polypropylene, polystyrene, polyethylene glycol, polyvinylpyrrolidone, polyvinyl alcohol, polyvinylpyrrolidone, polyacrylonitrile, polymethyl methacrylate, polyurethane, polyacrylamide, poly(acrylic acid), polyethylene oxide, poly(ethylene imine), carboxylmethyl cellulose, hydroxypropyl cellulose, polyethylene oxide, alkylated polyethylene oxide, cross- linked polyethylene oxide, polyvinyl ether, poly(methyl methacrylate), polyvinylidene fluoride, a copolymer of polyhexafluoropropylene and polyvinylidene fluoride, poly(ethyl acrylate), polytetrafluoro ethylene, polyvinyl chloride, polyacrylonitrile, derivatives, blends, or copolymers thereof.

[0031] In another aspect of the invention, the carbon-containing compound can be selected from the group consisting of organic carbon sources, including sucrose, glucose, lactose, maltodextrin, soluble starch, polymers (e.g. poly(ethylene glycol), poly(vinyl alcohol), poly(acrylic acid), polyvinyl pyrrolidone), vinyl alcohol, acrylic acid, citric acid, oxalic acid, and lauric acid; inorganic carbons; urea; and combinations thereof.

[0032] In an aspect the carbon source is an organic carbon source added in an amount equal to 0.00 wt% to 0.01 wt%, 0.01 wt% to 0.02 wt%, 0.02 wt% to 0.03 wt%, 0.02 wt% to 0.04 wt%, 5 105690391.2Docket No. 113544-856296 PCT APPLICATION 0.03 wt% to 0.04 wt%, 0.04 wt% to 0.2 wt%, 0.05 wt% to 0.2 wt%, 0.05 wt% to 0.1 wt%, 0.08 wt% to 0.15 wt%, or 0.1 wt% to 0.2 wt%.

[0033] In an embodiment, an organic carbon source is sucrose. The amount of sucrose for the precursor materials may be chosen such that there are about 1.0 to about 1.5 carbon atoms per transition metal atom in an initial slurry. In another embodiment, the amount of sucrose for the precursor materials may be chosen such that there are about 1.2 to about 1.5 carbon atoms per transition metal atom in an initial slurry. In another embodiment, the amount of sucrose for the precursor materials may be chosen such that there are 1.5 carbon atoms per transition metal atom in an initial slurry.

[0034] In the formula, M is one or more elements selected from the group of elements comprising at least one of Mn, Fe, Mg, V, Co, Ni, Zn, Ca, Na, Al, Cr, or Cu. Alternatively, M is one or more metal species not limited to the transition metals. In an embodiment, M is at least one of Mn, Fe, Mg and combinations thereof.

[0035] In an embodiment, M consists of the combination of Mn and Fe wherein the molar ratio of Mn:Fe ranges from about 1:1 to about 9:1. For example, the molar ratio of Mn:Fe ranges from about 1.5:1 to about 8:1, or the molar ratio of Mn:Fe ranges from about 2:1 to about 6:1, or the molar ratio of Mn:Fe ranges from about 2:1 to about 8:1, or the molar ratio of Mn:Fe ranges from about 2.4:1 to about 5:1, or the molar ratio of Mn:Fe ranges from about 2.6:1 to about 4:1, or the molar ratio of Mn:Fe ranges from about 1.5:1 to about 4:1. In another embodiment, the molar ratio of Mn:Fe ranges from about 2.8:1 to about 3.8:1, or the molar ratio of Mn:Fe ranges from about 2.8:1 to about 3.6:1, or the molar ratio of Mn:Fe ranges from about 2.8:1 to about 3.4:1, or the molar ratio of Mn:Fe ranges from about 2.8:1 to about 3.2:1. In an aspect, M consists of the combination of Mn and Fe wherein the molar ratio of Mn:Fe is about 3:1.

[0036] Furthermore, the Li-containing orthoborate material has a stoichiometry of Li1.04Mn0.96BO3. Alternatively, the Li-containing orthoborate material has a stoichiometry of Li1.08Mn0.92BO3. Optionally, the Li-containing orthoborate material comprises a stoichiometry of Li1.04Mn0.72Fe0.24BO3. In an embodiment, the Li-containing orthoborate material comprises a stoichiometry of Li1.08Mn0.69Fe0.23BO3. In some embodiments, the Li-containing orthoborate material comprises a stoichiometry of LiMn0.95BO3. In some other embodiments, the Li- containing orthoborate material comprises a stoichiometry of LiMn0.90BO3. 6 105690391.2Docket No. 113544-856296 PCT APPLICATION

[0037] Specifically, the sum of metal elements other than Li is less than 0.75, less than 0.8, less than 0.9 or less than 1.0 when normalized to the stoichiometry of boron. Alternatively, the sum of metal elements other than Li is equal to one when normalized to the stoichiometry of boron. In an embodiment, the sum of metal elements other than Li is less than one but greater than 0.7 when normalized to the stoichiometry of boron. EXAMPLES:

[0038] The embodiments of the invention are further illustrated by the following non-limiting examples. 1) Synthesis:

[0039] The synthesis of these materials was conducted by mixing appropriate amounts of Lithium Carbonate, Boric Acid, Manganese (II) Carbonate, and Sucrose. The targeted Li quantity was multiplied by 1.04. For the various materials shown here, the amount of sucrose was chosen such that there were 1.5 carbon atoms per transition metal atom in the initial slurry. These precursors were mixed together in distilled water, with a weight percentage of solids of 20%. 0.5 mm Zirconia beads were added to the slurry, where the mass of beads was twice the mass of the entire slurry (including water). The slurry, together with the beads, was milled in a planetary ball mill (MSE Supplies) at 600 rpm for a total active milling time of 96 min. The slurry was then passed through a mesh filter to remove the beads from the slurry. During this process, some additional water was utilized to rinse the jar, such that the final solids content of the slurry was 15%.

[0040] Afterwards, the slurry was spray dried (Yamato, GB210) with an outlet temperature of ~ 100 °C, an atomizing pressure of 0.2 MPa, and a blower rate of 0.5 m3 / min. The dried powder was then calcined at 600°C for 10h, with a ramping rate of 5°C per minute. For samples where M = Mn, the samples were calcined under flowing nitrogen (N2) gas. Conversely, for samples where M = Mn (75 %), Fe (25 %), the samples were calcined under a flowing gas mixture of 5% CO2and 95% N2. 2) Electrochemical Testing:

[0041] For the materials where M = Mn, the samples were immediately brought into a dry room after unloading from the furnace. They were then dried in a vacuum oven at 80 - 200°C 7 105690391.2Docket No. 113544-856296 PCT APPLICATION for at least 12 hours in order to remove residual moistures in the powder. All other cell components or chemicals are also vacuum dried in advance.

[0042] A FlackTek Speedmixer was used for slurry preparation. The material was mixed with PVDF, Carbon Black, and NMP such that the ratio of active material : PVDF : Carbon Black was 80 : 10 : 10. The amount of NMP to add was chosen to achieve a suitable viscosity for coating the electrode sheet. Note that we added PVDF via a premixed 10% PVDF in NMP solution.

[0043] Once the slurry was made, it was taken to a doctor blade coater. A carbon-coated aluminum sheet was vacuum mounted onto the coater chuck as the substrate. The chuck was heated to 60°C. For these samples, the doctor blade gap was set to 200 micrometers. The slurry was then cast onto the substrate by the doctor blade. After coating, the electrode was transferred into a forced air oven at 80°C to be dried for at least 4 hrs. Then, a Hohsen puncher was used to punch out coin disks (13.8mm in diameter) out of the electrode. Each disk was weighed in the dry room in order to know the precise active material amount for each cell. These disks were then vacuum dried under 80-110°C for at least 12 hrs in the antechamber attached to the glovebox. After drying, the disks were transferred into an Ar-filled glovebox without exposure to atmosphere.

[0044] For materials where M = Mn (75 %), Fe (25 %), a similar procedure was performed. Upon unloading from the furnace, the M = Mn (75%), Fe (25%) material samples were transferred under N2to an argon-filled glovebox. Then, inside the glovebox, they were mixed with PVDF, Carbon Black, and NMP such that the ratio of active material : PVDF : Carbon Black was 80 : 10 : 10. The amount of NMP to add was chosen to achieve a suitable viscosity for coating the electrode sheet. Note that we added PVDF via a premixed 10% PVDF / NMP solution. The mixing in this case was done manually with a stir bar. Once the slurry was made, it was cast onto a carbon-coated aluminum sheet which was mounted on a glass substrate. The casting was done manually via a doctor blade with a gap of 200 micrometers. After coating, the slurry was dried under vacuum at 80 - 110°C overnight. These samples were then punched into coin disks (13.8mm in diameter) using a Hohsen puncher. They were weighed in the dry room with minimal (< 5 min) exposure to dry air before being returned to the glovebox.

[0045] Regardless of the identity of M, the following steps were identical. In the glovebox, the disks were made into 2032 coin cells with a PP / PE / PP separator, Li metal as the anode and 8 105690391.2Docket No. 113544-856296 PCT APPLICATION LP58 electrolyte. The cells were then loaded into temperature-controlled chambers connected to battery testers (Arbin) and were cycled. All testing shown here was conducted at 45°C. For the results shown in Table 3 and Table 5 below, the cells were cycled at 22 mA g-1to an upper cutoff voltage of 4.6 V. They were then held at that voltage until the current decayed to 4.4 mA g-1. Following this, they were discharged again at 22 mA g-1, corresponding to an approximately C / 10 cycling rate, to a lower cutoff voltage of 2 V.

[0046] For the ‘GITT protocol’ referred to in the results section below, the cells were subjected to a galvanostatic intermittent titration technique experiment in which the cell experienced two 22 mAh g-1charging steps at a C / 10 current rate followed by 22 mAh g-1discharging steps until reaching a lower cutoff voltage of 2V. Between each charging / discharging step, the cell was rested for 24 hours. RESULTS a) Materials where M = Mn Example 1: LiMnBO3vs Li1.08Mn0.92BO3

[0047] FIG. 1 shows the XRD pattern, plotted with the square root of intensity of standard LiMnBO3 on the y axis. The reference pattern is the one in which the sample, prepared under identical conditions except for the stoichiometry, had a nominal stoichiometry of Li1.08Mn0.92BO3. It can be seen that this sample showed no new XRD peaks. Additionally, there was a small shift in the diffraction peaks, indicative of a change in the lattice volume (see Table 1 below). Both of these observations are consistent with the formation of a substoichiometric lithium transition metal orthoborate with a stoichiometry of Li1.08Mn0.92BO3. The sharper peaks of Li1.08Mn0.92BO3 indicated a larger crystallite size for that sample. Example 2: LiMnBO3 vs LiMn0.9BO3

[0048] Referring to FIG. 2, an alternative route of achieving a substoichiometric orthoborate material was demonstrated by preparing the compound LiMn0.9BO3. FIG. 2 shows the XRD pattern of standard LiMnBO3, with the square root of intensity plotted on the y axis, and the XRD pattern for LiMn0.9BO3. Again, there are no new diffraction peaks and a slight shift in the peak positions indicative of a change in the lattice volume (see Table 1 below). The sharper peaks of LiMn0.9BO3 indicated a larger crystallite size for that sample. 9 105690391.2Docket No. 113544-856296 PCT APPLICATION

[0049] Typically, when the composition of the material is modified, the lattice volume will be modified as the crystal may distort to better accommodate the new composition. The lattice volume for a series of orthoborate samples with different nominal compositions appears in the table below, with the percentage change compared to the LiMnBO3 baseline composition shown in brackets. Table 1. Composition Volume (Å3) [% change] LiMnBO3 485.102 [0 %] Li1.04Mn0.96BO3 484.632 [- 0.097 %] Li1.08Mn0.92BO3484.278 [- 0.170 %] LiMn0.95BO3 484.597 [- 0.104 %] LiMn0.9BO3484.439 [- 0.137 %] The lattice volume of standard LiMnBO3 and those of substoichiometric lithium transition metal orthoborates. It can be seen that increasing the value of x in Li1+xM1-xBO3 or in Li1M1-xBO3 causes a monotonic decrease in the lattice volume, which may be due to the smaller size of Li+and Mn3+in comparison to Mn2+.

[0050] In Table 1 above, the majority phase (> 95%), to which the lattice volumes refer, was fit with the monoclinic C2 / c (# 15) space group, as has been reported in studies conducted by others. See DOI: 10.1002 / adma.201001039 for details about the structural model used to fit the data, also described in Table 2 below. Note that for the hexagonal P6^space group #174, as described in claim 3, a description of the relevant structural model can be found in the following work with DOI: 10.1016 / S0167-2738(00)00813-4. Table 2. Atom x y z Li 0.634 0.502 0.124 Mn 0.1616 0.3348 0.1259 B 0.153 0.660 0.121 O 0.405 0.1640 0.0950 O 0.780 0.3120 0.1581 O 0.320 0.5394 0.1308 10 105690391.2Docket No. 113544-856296 PCT APPLICATION Details of the structural model used to fit the material with the C2 / c monoclinic space group (#15). The space group used was C2 / c (#15). Initial lattice parameters were set to a = 5.204375 Å, b = 8.976579 Å, c = 10.380446 Å, β = 91.8464°. Parameters that could be varied include, but are not limited to, lattice parameters, crystallite size, isotropic strain, anisotropic strain, atomic displacement parameters, site occupancies, instrumental parameters, background, and atomic positions.

[0051] As can be seen in Table 1, as x increases in either Li1+xM1‑xBO3or Li1M1-xBO3, the lattice volume monotonically decreases. This may be due to the smaller size of Li+and Mn3+in comparison to Mn2+. We note that, relative to the nominal compositions, the Li amount was always increased by a factor of 1.04.

[0052] Electrochemically, substoichiometric lithium transition metal orthoborates were found to offer improved electrochemical properties in terms of specific capacity and reversibility. In terms of specific capacity, Table 3 below compares the first discharge capacity of standard LiMnBO3with those of substoichiometric lithium transition metal orthoborates Li1.04Mn0.96BO3and Li1.08Mn0.92BO3. Again, all samples were synthesized under identical conditions other than the material stoichiometry. The electrochemical testing was carried out under identical conditions as those discussed above in paragraph

[0036] , and the percentage change compared to the LiMnBO3is shown in brackets. Table 3. Composition Specific Capacity (mAh / g) [% change] LiMnBO3 87 [0 %] Li1.04Mn0.96BO3104 [+ 19.5 %] Li1.08Mn0.92BO398 [+ 12.6 %] The first discharge capacity of lithium manganese orthoborates, with the second and third rows representing substoichiometric lithium transition metal orthoborates.

[0053] In addition, improved reversibility was found. FIG. 4 shows the electrochemical behavior under the ‘GITT Protocol’ of a standard LiMnBO3 compound together with that of a substoichiometric lithium transition metal orthoborate with composition Li1.04Mn0.96BO3. The cycling procedure used was explained in the Electrochemical Testing section above and is referred to as the ‘GITT Protocol’. It can be seen that the standard LiMnBO3 compound was unable to reintercalate all of the lithium removed on charging before reaching the lower cutoff voltage of 2V. In contrast, the Li1.04Mn0.96BO3compound was able to reintercalate all of the 11 105690391.2Docket No. 113544-856296 PCT APPLICATION lithium removed on charging, showing improved reversibility for the substoichiometric lithium transition metal orthoborate. b) Materials where M = Mn, Fe Example 3: LiMn0.75Fe0.25BO3 vs Li1.04Mn0.72Fe0.24BO3 and Li1.08Mn0.69Fe0.23BO3

[0054] While the above examples involved compositions where M = Mn, evidence of the successful synthesis of substoichiometric lithium transition metal orthoborates was also found when M = Mn (75%), Fe (25%). FIG. 3 shows the XRD pattern of standard LiMn0.75Fe0.25BO3, with the square root of intensity plotted on the y axis as well as the XRD pattern of Li1.08Mn0.69Fe0.23BO3. Again, there were no new diffraction peaks and a slight shift in the peak positions indicative of a change in the lattice parameters (see Table 4 below). Table 4. Composition Volume (Å3) [% change] LiMn0.75Fe0.25BO3480.684 [0 %] Li1.04Mn0.72Fe0.24BO3480.142 [-0.113 %] Li1.08Mn0.69Fe0.23BO3 479.848 [-0.174 %] The lattice parameters of standard LiMn0.75Fe0.25BO3and those of substoichiometric lithium transition metal orthoborates Li1.04Mn0.72Fe0.24BO3 and Li1.08Mn0.69Fe0.23BO3. It can be seen that increasing the value of x in Li1+xM1-xBO3, with M = Mn (75 %), Fe (25 %), causes a monotonic decrease in the lattice volume. This decrease in lattice volume may be due to the smaller size of Li+and Fe3+in comparison to Fe2+.

[0055] For materials where M = Mn (75 %), Fe (25 %), improved electrochemical performance was also found. As shown in Table 5 below, the electrochemical first discharge capacity was higher for both examples of substoichiometric lithium transition metal orthoborates when compared to that of the standard LiMn0.75Fe0.25BO3 (which contains a sum of metal elements other than Li equal to one). Table 5. Composition Specific Capacity (mAh / g) [% change] LiMn0.75Fe0.25BO3122 [0 %] Li1.04Mn0.72Fe0.24BO3 135 [+ 10.7 %] Li1.08Mn0.69Fe0.23BO3153 [+ 25.4 %] 12 105690391.2Docket No. 113544-856296 PCT APPLICATION The first discharge capacity of standard LiMn0.75Fe0.25BO3 and those of substoichiometric lithium transition metal orthoborates Li1.04Mn0.72Fe0.24BO3 and Li1.08Mn0.69Fe0.23BO3. It can be seen that increasing the value of x in Li1+xM1-xBO3, with M = Mn (75 %), Fe (25 %) causes an increase in the initial discharge capacity of these samples.

[0056] Additionally, an improvement in the hysteresis was seen. FIG. 5 shows the results from subjecting LiMn0.75Fe0.25BO3, Li1.04Mn0.72Fe0.24BO3, and Li1.08Mn0.69Fe0.23BO3 to the ‘GITT Protocol’.

[0057] It can be seen that the two substoichiometric lithium transition metal orthoborates exhibited an improved (i.e. smaller) hysteresis when compared to the standard LiMn0.75Fe0.25BO3. The hysteresis here is defined as the difference between the charging voltage and discharging voltage at a particular state of charge (i.e. a particular capacity value).

[0058] The preceding examples can be repeated with similar success by substituting the generically or specifically described parameters of this invention for those used in the preceding examples.

[0059] Although the invention has been described in detail with particular reference to these described embodiments, other embodiments can achieve the same results. Variations and modifications of the present invention will be obvious to those skilled in the art and it is intended to cover in the appended claims all such modifications and equivalents. The entire disclosures of all references, applications, patents, and publications cited above are hereby incorporated by reference. DEFINITIONS

[0060] All publications, patents and patent applications cited herein, whether supra or infra, are hereby incorporated by reference in their entirety to the same extent as if each individual publication, patent, or patent application were specifically and individually indicated to be incorporated by reference.

[0061] The terms “comprising,” “including,” “having” and their derivatives, are not intended to exclude the presence of any additional component, step, or procedure, whether or not the same is specifically disclosed. In order to avoid any doubt, all compositions claimed through use of the term “comprising” may include any additional additive, adjuvant, or compound, whether polymeric or otherwise, unless stated to the contrary. 13 105690391.2Docket No. 113544-856296 PCT APPLICATION

[0062] The term “or” unless stated otherwise, refers to the listed members individually as well as in any combination. Use of the singular includes use of the plural and vice versa.

[0063] The terms “a,” “an,” “the” and similar referents used in the context of describing the inventive features (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. Thus, for example, reference to a “starch” may include one, two or more starches.

[0064] The term “composition” refers to a mixture of materials which comprise the composition, as well as reaction products and decomposition products formed from the materials of the composition. The term “material” may be understood to be a “composition”, as defined herein.

[0065] The term “LMP” used in reference to the cathode material refers to “lithium-transition metal-phosphate.” As used herein, “LFP” refers to “lithium iron phosphate.”

[0066] “Capacity” of a battery or battery cell is a measure of the charge stored by the battery and is determined by the active materials contained in the battery. The capacity represents the maximum amount of charge that can be extracted from the battery under certain specified conditions. The battery has a discharge current in amperes that can be delivered over time. The capacity of the battery is given in ampere-hours (Ah).

[0067] “Gravimetric capacity” is the capacity per unit mass (mAh / g). Gravimetric capacity is also referred to as specific discharge capacity.

[0068] Unless otherwise stated, all percentages, ratios, parts, and amounts used and described herein are by weight.

[0069] Numbers, percentages, ratios, or other values stated herein may include that value, and other values that are about or approximately the stated value, as would be appreciated by one of ordinary skill in the art. A stated value should therefore be interpreted broadly enough to encompass values that are at least close enough to the stated value to perform a desired function or achieve a desired result, and / or values that round to the stated value. The stated values include at least the variation to be expected in a typical manufacturing process, and may include values that are within 25%, 15%, 10%, within 5%, within 1%, etc. of a stated value.

[0070] “wt%” as used herein refers to the percent ratio of the mass of the non-fluid particles or dissolved solids relative to the total mass of said mixture. For example, mass of the particles 14 105690391.2Docket No. 113544-856296 PCT APPLICATION of ions, additional compounds, and / or dopants in a given mixture relative to the total mass of the olivine-type LMP material.

[0071] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. The initial definition provided for a group or term herein applies to that group or term throughout the present specification individually or as part of another group unless otherwise indicated. 15 105690391.2

Claims

Docket No. 113544-856296 PCT APPLICATION CLAIMS What is claimed is:

1. A Li-containing orthoborate material having the formula Li1+xM1-xBO3, wherein M comprises a transition metal; wherein 0 < x < 0.3, and wherein the Li-containing orthoborate material has a specific capacity greater than a Li containing orthoborate material having the formula LiMBO3.

2. The Li-containing orthoborate material of claim 1, wherein a majority phase by X-ray diffraction analysis is described by the C2 / c monoclinic space group #15.

3. The Li-containing orthoborate material of claim 1, wherein a majority phase by X-ray diffraction analysis is described by the P6^hexagonal space group #174.

4. The Li-containing orthoborate material of claim 1, wherein M comprises at least one of Mn, Fe, Mg, V, Co, Ni, Zn, Ca, Na, Al, Cr, and Cu.

5. The Li-containing orthoborate material of claim 4, wherein M is selected from the group consisting of Mn, Fe, Mg, and combinations thereof.

6. The Li-containing orthoborate material of claim 5, wherein M consists of the combination of Mn and Fe in a Mn:Fe molar ratio ranging from about 1:1 to about 9:

1.

7. The Li-containing orthoborate material of claim 5, wherein M consists of the combination of Mn and Fe in a Mn:Fe molar ratio ranging from about 1.5:1 to about 4:

1.

8. The Li-containing orthoborate material of claim 5, wherein M consists of the combination of Mn and Fe in a Mn:Fe molar ratio of about 3:

1.

9. The Li-containing orthoborate material of claim 4, wherein the Li-containing orthoborate material is Li1.04Mn0.96BO3. 16 105690391.2Docket No. 113544-856296 PCT APPLICATION 10. The Li-containing orthoborate material of claim 4, wherein the Li-containing orthoborate material is Li1.08Mn0.92BO3.

11. The Li-containing orthoborate material of claim 4, wherein the Li-containing orthoborate material is Li1.04Mn0.72Fe0.24BO3.

12. The Li-containing orthoborate material of claim 4, wherein the Li-containing orthoborate material is Li1.08Mn0.69Fe0.23BO3.

13. A Li-containing orthoborate material having the formula LiM1-xBO3, wherein M comprises a transition metal; wherein 0 < x < 0.3, and wherein the Li-containing orthoborate material has a specific capacity greater than a Li- containing orthoborate material having the formula LiMBO3.

14. The Li-containing orthoborate material of claim 13, wherein M comprises at least one of Mn, Fe, Mg, V, Co, Ni, Zn, Ca, Na, Al, Cr, and Cu.

15. The Li-containing orthoborate material of claim 13, wherein M is selected from the group consisting of Mn, Fe, Mg, and combinations thereof.

16. The Li-containing orthoborate material of claim 13, wherein the Li-containing orthoborate material is LiMn0.95BO3.

17. The Li-containing orthoborate material of claim 13, wherein the Li-containing orthoborate material is LiMn0.90BO3. 17 105690391.2

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