An anode active material based on mixed oxides of nb 2o 5

Abstract

An active anode material for use in a battery in which the active anode material represents mixed oxides of titanium, molybdenum, and niobium corresponding to the formula: TixNbyMO2-yOa wherein x, y, and a represent molar amounts with x ≥ 0.5, y ≤ 1.7, x / y ≥ 0.5, and a > 6.0.

Description

AN ANODE ACTIVE MATERIAL BASED ON MIXED OXIDES OF Nb2O5FIELD

[0001] This disclosure generally relates to anode active materials based on mixed oxides that include niobium pentoxide (Nb20s). This disclosure further relates to batteries that incorporate these niobium pentoxide-based mixed oxides as an anode active material.BACKGROUND

[0002] The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.

[0003] The occurrence of market growth relative to electric vehicles and portable electronic devices has driven the need for energy storage systems that overcome the numerous disadvantages associated with prior technologies. In this respect niobium (V) oxide, i.e. , Nb20s, has been investigated for use as a high-rate anode for alkaline metal ion batteries because of its cyclic stability, high capacity, and excellent reversibility.

[0004] Titanium niobium oxide (abbreviated as TNO) also has been investigated for use as an alternative to graphite and Li4TisOi2 because it is capable of providing a better rate and higher energy density, as well as exceptional safety characteristics. TNO or TiNb20? represents an electrode material that has a crystallographic structure and high ionic conductivity, which may be useful for use as a high-power anode material.

[0005] Each different type of electrochemical energy storage technology generally comes with a variety of trade-offs, i.e., there is no single material capable of being used for all applications. Although the use of TNO as an anode active material offers several advantages, there are opportunities to further increase the material’s capacity and rate performance. In addition, one of the major concerns for TNO is that it contains a high content of niobium (76.9 wt.% of Nb2Os) with production being expensive and supply being geographically limited. Thus, there is a need to reduce the niobium content in the anode active material in order to reduce the raw material cost and to diversify the raw material supply chain, without sacrificing any electrochemical performance.SUMMARY

[0006] This disclosure relates generally to anode active materials based on mixed oxides that include niobium pentoxide (NbzOs) and batteries that incorporate these anode active materials.

[0007] According to one aspect of the present disclosure, the active anode material comprises mixed oxides of titanium, molybdenum, and niobium corresponding to the formula:TixNbyMO2-yOa wherein x, y, and a represent molar amounts with x > 0.5, y < 1 .7, x / y > 0.5, and a > 6.0. Alternatively, x may be greater than or equal to 1.0; alternatively, x > 1.5; alternatively x is within the range of 0.6 to 1.6. When desirable, y may be less than or equal to 1 .5; alternatively, y is within the range of 1 .3 to 1 .7.

[0008] According to another aspect of the present disclosure the titanium / niobium molar ratio (x / y) is greater than or equal to 0.6. Alternatively, the ratio of x / y is in the range of 0.5 to 1 .0 .

[0009] The mixed oxides of titanium, molybdenum, and niobium may comprise one or more of TiC>2, MoOs, and Nb20s. Several examples of the anode active material formed in the present disclosure may corresponds to, but not be limited to, the formula of Tio.8Nbl.6MOo.4O6.8 or Tio.67Nbl .33MOo.6706.67.

[0010] The mixed oxides of the active anode material may further include one or more anions comprising fluorine, boron, or sulfur and / or one or more metal cations comprising a transition metal or a non-transition metal. The anions comprising boron may form a borate oxyanion selected from the group consisting of orthoborate BO33, metaborate BO-2, tetraborate B4O2‘7, and a mixture thereof. The one or more metal cations may be selected from the group consisting of zinc, copper, nickel, cobalt, vanadium, magnesium, calcium, and aluminum. These anions and / or metal cations in the mixed oxides may be present in an amount that is less than or equal to 20 wt.% based on the overall weight of the active anode material.

[0011] According to another aspect of the present disclosure, a battery is formed that comprises an electrolyte and the active anode material described above and further defined herein. This battery may be an alkaline ion battery, wherein the electrolyte comprises lithium ions, sodium ions, or potassium ions.

[0012] According to yet another aspect of the present disclosure, a method of forming the active anode material is described. This method generally comprises: providing a source of titanium oxide, a source of molybdenum oxide, and a source of niobium oxide; mixing together the source of titanium oxide, the source of molybdenum oxide, and the source of niobium oxide to form a mixed oxide; and sintering the mixed oxide in the temperature range of 800°C to 1 ,350°C for a time period of 1 to 48 hours to obtain the active anode material.

[0013] When desirable, the mixed oxide may be sintered upon exposure to the temperature range of 1 ,000°C to 1 ,200°C for a time period of 2 to 24 hours to obtain the active anode material. Alternatively, the temperature range used to sinter the mixed oxide may be 1 ,100°C to 1 ,150°C for a time period of 6 to 12 hours in order to obtain the active anode material.

[0014] The source of titanium oxide, the source of molybdenum oxide, and the source of niobium oxide used in this method are selected from the group consisting of particles of TiCh, MoOs, and Nb2Os, chemical compounds of titanium, molybdenum, and niobium that decompose into metal oxides at the sintering temperature, and a combination of the particles and the chemical compounds.

[0015] When desirable or necessary, the method may further comprise the step of milling one or more of the particles of titanium oxide, molybdenum oxide, and niobium oxide to reduce average particle size.

[0016] Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.DESCRIPTION OF THE DRAWINGS

[0017] In order that the disclosure may be well understood, there will now be described various forms thereof, given by way of example, reference being made to the accompanying drawings.

[0018] Fig. 1A is a graphical representation of an x-ray diffraction (XRD) spectrum measured for a conventional TiNb2O? active anode material.

[0019] Fig. 1 B is a graphical representation of an x-ray diffraction (XRD) spectrum measured for a Ti0.8Nb1.6Mo0.4O68 active anode material formed according to the teachings of the present disclosure.

[0020] Fig. 2A is a scanning electron micrograph (SEM) image measured for the conventional TiNt^O? active anode material of Fig. 1A.

[0021] Fig. 2B is a scanning electron micrograph (SEM) image measured for the Ti0.8Nb1.6Mo0.4O68 active anode material of Fig. 1 B.

[0022] Fig. 3A is a graphical comparison of the 1stcycle charge and discharge voltage curves plotted as a function of specific capacity measured for electrochemical cells containing TiNb2O? or Ti0.8Nb1.6Mo0. O6.8 as active anode materials.

[0023] Fig. 3B is a graphical comparison of the C rate measured for electrochemical cells containing TiNb2O? or Ti0.8Nb1.6Mo0.4O6.8 as active anode materials.

[0024] Fig. 3C is a graphical comparison of the cycling stability for electrochemical cells containing TiNb2O? or Ti0.8Nb1.6Mo0.4O68 as active anode materials shown as measured reversible capacity plotted as a function of cycle number.

[0025] Fig. 4A is a graphical comparison of the C rate measured for electrochemical cells containing TiNb2O? or Ti0.67Nb1.33Mo0.67O6.67 as active anode materials.

[0026] Fig. 4B is a graphical comparison of the cycling stability for electrochemical cells containing TiNb2O7 or Ti0.67Nb1.33Mo0.67O667 as active anode materials shown as measured reversible capacity plotted as a function of cycle number.

[0027] Fig. 5A is a graphical representation of the reversible specific capacity plotted as a function of niobium content measured for TixNbyMo2-yOa as the active anode material.

[0028] Fig. 5B is a graphical representation of the specific capacity plotted as a function of molybdenum content measured for TixNbyMo2-yOaas the active anode material.

[0029] Fig.6 is a graphical representation of the specific capacity plotted as a function of titanium content measured for TixNbyMo2-yOaas the active anode material.

[0030] Fig.7 is a graphical representation of the specific capacity plotted as a function of titanium / niobium molar ratio measured for TixNbyMo2-yOaas the active anode material.

[0031] Fig.8 is a flowchart describing a method of forming an active anode material according to the teachings of the present disclosure.

[0032] Fig. 9 is a schematic representation of a battery that incorporates an active anode material formed according to the teachings of the present disclosure.

[0033] The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way.DETAILED DESCRIPTION

[0034] The following description is merely exemplary in nature and is in no way intended to limit the present disclosure or its application or uses. For example, niobium pentoxide-based mixed oxides made and used according to the teachings contained herein are described throughout the present disclosure in conjunction with alkaline metal ion batteries in order to more fully illustrate the composition and the use thereof. The incorporation and use of such active anode materials in other types of electrochemical cells or batteries used in high power applications, such as power supplies for electric vehicles (EVs) and hybrid electric vehicles (HEVs), as well as in smart grids, capacitors, supercapacitors, sensors, and fuel cells is contemplated to be within the scope of the present disclosure. It should be understood that throughout the description, corresponding reference numerals indicate like or corresponding parts and features.

[0035] The present disclosure generally provides an anode active material based on mixed oxides of niobium pentoxide (Nb20s) for use in an electrochemical cell or a battery, such as an alkaline metal ion battery. This active anode material generally comprises a mixture of TiCk, Nb20s, and MoOs. The mixed oxides of titanium, molybdenum, and niobium that are present in the active anode material correspond to formula (F-1 ):TixNbyMO2-yOa (F-1) wherein x, y, and a represent molar amounts with x > 0.5, y < 1 .7, x / y > 0.3, and a > 6.0. The addition of molybdenum to the active anode material effectively reduces the amount of niobium that is present in the active anode material, thereby, addressing the deficiencies with respect to TiNb2O? or TNO as discussed above and as further described herein.

[0036] The molar amounts of x, y, and a as set forth in formula F-1 may be scaled up or down to various values without departing from the scope of the present disclosure. Such scaling is evident in the literature for the case of conventional TNO, wherein the composition has been described as TiNb2O?, Ti2Nb40i4, or Tio.sNbOs.s. Regardless of the various scaled formulas, the composition of the TNO material remains unchanged. The molybdenum-titanium-niobium oxide materials described by formula F-1 may be scaled-up or scaled-down in a similar fashion using any numerical factor without departing from the scope of the present disclosure. For example, the formula for anactive anode material corresponding to Ti0.8Nb1.6Mo0.4O68 may be scaled-up by a factor of 1 .25 to be described as TiNb2Moo.s08.5 or scaled-down by a factor of 0.30 to be described as Tio 24Nbo 48Moo i202 o. This scaled-down formula Tio.24Nbo.48Moo.i202.o corresponds to the molar quantity of each element present in the mixed oxide anode composition comprising a mass ratio of Ti©2 at 19.12 wt.%, of MoOs at 17.23 wt.%, and of Nb2C>5 at 63.64 wt.% relative to the overall weight of the active anode material. In each case, these formulas for the active anode material are the same with the scaled formulas being capable of being reduced to the formula described by (F-1 ) with the molar amount of niobium defined by subscript y < 1.7 and the molar amount of molybdenum defined by subscript 2-y.

[0037] Since the active anode material is an oxide there needs to be enough oxygen anions to balance the overall charge, i.e., the value of the subscript a in formula F-1 will need to be > 6.0. The value of subscript a is at its maximum when all the metal ions reach their highest oxidation states (Ti4+, Mo6+, and Nb5+). The mixed oxides of titanium, molybdenum, and niobium in this active anode material may comprise one or more metal oxides besides TiCh, M0O3, and Nb20s without departing from the scope of the present disclosure.

[0038] For the purpose of this disclosure, the terms "at least one" and "one or more of” an element are used interchangeably and may have the same meaning. These terms, which refer to the inclusion of a single element or a plurality of the elements, may also be represented by the suffix "(s)"at the end of the element. For example, "at least one transition metal", "one or more transition metals", and "transition metal(s)" may be used interchangeably and are intended to have the same meaning.

[0039] For the purpose of this disclosure the terms "about" and "substantially" are used herein with respect to measurable values and ranges due to expected variations known to those skilled in the art (e.g., limitations and variability in measurements).

[0040] For the purpose of this disclosure, the term "weight" refers to a mass value having the units of grams, kilograms, and the like. Further, the recitations of numerical ranges by endpoints include the endpoints and all numbers within that numerical range. For example, an amount ranging from 40% by weight to 65% by weight (also written as 40 wt.% to 65 wt.%) includes concentrations of 40% by weight, 65% by weight, and all concentrations there between (e.g., 40.1 %, 41 %, 45%, 50%, 52.5%, 55%, 59%, 63%, etc.).

[0041] The Ti-Mo-Nb mixed oxide materials of the present disclosure contain a reduced content of niobium (e.g., Nb20s < 65 wt.%), while exhibiting either the same or improved electrochemical performance as compared to a conventional TiNbsO? (abbreviated as TNO) active anode material.

[0042] Molybdenum oxides (e.g., MoOs) provide an attractive replacement for niobium oxide (e.g., Nb20s) in an active anode material because it represents a less expensive material with greater geographic availability. In other words, the production of MoOs is more diversified among several countries with a better manageable supply chain than Nb20s. For example, in 2022 China produced 100,000 million tons (MT) of Molybdenum, while Chile produced 44,000 MT and the United States produced 42,000 MT. In comparison, Brazil produced only 71 ,000 MT of niobium in 2022, followed by Canada at 6,500 MT. The process for the production of molybdenum is also less expensive or more cost effective than the production process for niobium.

[0043] Referring now to Figs. 1A and 1 B, the formation of Tio.aNbi eMoo^Oe.a as compared to conventional TiNb2O? is demonstrated by the comparison of the x-ray diffraction (XRD) patterns measured for the conventional TNO material 5 (Fig. 1A) and the active anode material of the present disclosure 10 (Fig. 1 B). In addition, upon the replacement of 17% of Nb with Mo, the conventional TNO active anode material 5 was observed by scanning electron microscopy (SEM) to change particle morphology from irregular shapes as shown in Fig. 2A to elongated needle shapes for the Ti0.8Nb1.6Mo0.4O68 active cathode material 10 of the present disclosure as shown in Fig. 2B.

[0044] Referring now to Figs. 3A, 3B, and 3C, the electrochemical performance of a half-cell containing a conventional TiNb2O? active anode material 5 is compared to a similar half-cell containing a Tio8Nb1 6Moo 4O68 active anode material 10 of the present disclosure. As shown in Fig. 3A, the 1stcycle charge and discharge voltage curves measured for the half- cells containing the different active anode materials were found to be essentially the same. However, the half-cell containing the Tio.8Nb1 6Moo.4O68 active anode material 10 was observed to provide superior cycling stability as compared to the half-cell containing the conventional TiNb2O? active anode material 5 as shown in Fig. 3B. In addition, as shown in Fig. 3C, the half-cell containing the Tio.8Nb1.6Moo.4O68 active anode material 10 was observed to provide a higher reversible capacity (i.e., 229 mAh / g) and rate stability as compared to the reversible capacity (i.e., 221 mAh / g) and rate stability measured for the half-cell containing theconventional TiNb2O? active anode material 5. Thus, the replacement of niobium with molybdenum in the active anode material not only reduces the cost of the raw materials and enhances the diversity of the raw materials supply chain, but also improves or enhances the material’s electrochemical performance as a battery anode active material.

[0045] According to another example of the present disclosure, an active anode material 10 according to the formula, Ti0.67Nb1.33Mo0.67O6.67, which corresponds to formula F-1 was prepared and tested. The formula for this active anode material may be scaled-up, for example, by a factor of 1 .5 to be described as TiNb2MoOw or scaled- down by a factor of 0.30 to be described as Tio.2oNbo.4iMoo.2o02.o. This scaled-down formula Tio.2oNbo.4i Moo.2o02.o corresponds to the molar quantity of each element present in the mixed oxide anode composition comprising a mass ratio of TiC>2 at 16.3 wt.%, of MoOs at 29.4 wt.%, and of Nb2Os at 54.3 wt.% relative to the overall weight of the active anode material.

[0046] Referring now to Figs. 4A and 4B, a half-cell comprising this active anode material 10 exhibited the same or superior reversible specific capacity (i.e., 200 mAh / g), rate stability, and stable cycling life as compared to a half-cell containing the conventional TNO active anode material 5. Although the specific capacity measured for the half-cell containing the Ti0.67Nb1.33Mo0.67O6.67 of the present disclosure 10 was slightly lower than the specific capacity measured for the half-cell containing the TNO active anode material 5 at 0.1 C, the half-cell containing the Ti0.67Nb1.33Mo067O6.67 active anode material 10 exhibited similar capacity at 1 C as the half-cell containing the TNO active anode material 5 along with better cycling stability. A reversible specific capacity on the order of 200 mAh / g capacity may be utilized for most practical electrochemical applications.

[0047] Referring now to Figs. 5A, 5B, and 6 the effect of niobium (Nb) content, molybdenum (Mo) content, and titanium (Ti) content on the specific capacity exhibited by half-cells containing the mixed oxide active anode material according to formula F- 1 was measured. The effect of the Mo content, niobium content and Ti content was found to be represented by a non-linear relationship, which suggests the occurrence of a synergetic effect between the titanium, molybdenum, and niobium present in the mixed oxide anode material. However, as demonstrated in Figs. 5B and 6, the substitution of a higher titanium and / or molybdenum content for niobium content in the active anode material is generally preferred without degradation in specific capacity.

[0048] Still referring to Figs. 5A, 5B, and 6, the niobium content (y) in the active anode material according to formula F-1 of TixNbyMo2-yOa, should be less than 2.0 (y < 2.0); alternatively, y < 1.85; alternatively, y < 1.70; alternatively, y < 1.5; alternatively, y < 1.3; alternatively, in the range of 1.3 to 1.7. The molybdenum content in the active anode material of formula F-1 is given as the quantity of (2 - y), wherein y reflects the niobium content above. The titanium content (x) in the active anode material of formula F-1 should be greater than zero (x > 0); alternatively, x > 0.5; alternatively, x > 1.0; alternatively, x > 1.5. Alternatively, the titanium content may range from about 0.60 to about 1 .85; alternatively, in the range from about 0.60 to about 1 .6, while the molybdenum content ranges from about 0.15 to about 1.0; alternatively, from about 0.30 to about 0.70.

[0049] Due to the much lower cost of TiOz as compared to NbsOs and MoOs, a high content of titanium is generally preferred. Referring now to Fig. 7, the Ti / Nb molar ratio of this active anode material according to formula F-1 is preferred to be x / y > 0.5, alternatively x / y > 0.6, alternatively x / y > 0.7; alternatively x / y > 0.9. Alternatively, the Ti / Nb molar ratio in the anode active material is in the range of 0.5 < x / y < 1.0.

[0050] An anode active material in which the sum of the molybdenum and niobium molar content is 2.0 corresponds to a material in which the niobium in TNO has been partially replaced with molybdenum.

[0051] The amount of oxygen (a) present in the active anode material of formula F- 1 of TixNbyMo2-yOais generally in the range of 6 < a < 10. Alternatively, the amount of oxygen present in the active anode material corresponds to a > 6.0; alternatively, a > 6.5; alternatively, a > 6.67; alternatively, a < 8.5.

[0052] According to another aspect of the present disclosure, the mixed oxide anode active material of the present disclosure may include at least one more chemical element besides titanium, molybdenum, niobium, and oxygen. This chemical element may be fluorine, boron, or sulfur, which is present in the mixed oxide in the form of anion. The anions comprising boron may form a borate oxyanion selected from the group consisting of orthoborate BO33, metaborate BO-2, tetraborate B4C>2‘7, and a mixture thereof.

[0053] The chemical element may also be a metal, i.e., either a transition metal or a non-transition metal, which is present in the mixed oxide as a cation. Examples of transition metals include, without limitation, Zn, Cu, Ni, Co, and V. Examples of nontransition metals include, without limitation, Mg, Ca, and Al. The overall amount of theanions or cations in the active anode material is relatively small as compared to amount of Ti, Mo, Nb, and O present in the mixed oxide. The overall amount of anions and cations present is generally < 20 wt.%; alternatively, < 10 wt.%; alternatively, < 5 wt.%; alternatively, in the range of 0.01 wt.% to 4 wt.% relative to the overall composition of the mixed oxide active anode material.

[0054] According to yet another aspect of the present disclosure a method of forming the active anode material according to formula F-1 is provided. Referring now to Fig. 8, this method 50 generally comprises providing 55 a source of titanium oxide, a source of molybdenum oxide, and a source of niobium oxide; mixing 60 together the source of titanium oxide, the source of molybdenum oxide, and the source of niobium oxide to form a mixed oxide; and sintering 65 the mixed oxide to obtain the active anode material. The mixed oxide may be sintered in the temperature range of 800°C to 1 ,350°C for a time period of 1 to 48 hours; alternatively, the sintering temperature may be in the range of 1 ,000°C to 1 ,200°C; alternatively, in the range of 1 ,100°C to 1 ,150°C. The time period for which the mixed oxide is exposed to the sintering temperature may alternatively, be in the range of 2 to 24 hours; alternatively, 6 to 12 hours.

[0055] The source of titanium oxide, the source of molybdenum oxide, and the source of niobium oxide provided in the method 50 may be selected from the group consisting of particles of TiC>2, M0O3, and Nb2Os, chemical compounds of titanium, molybdenum, and niobium that decompose into metal oxides at the sintering temperature, and a combination of such particles and chemical compounds.

[0056] In other words, the mixed oxide active anode material according to formula F- 1 may be prepared through a solid state process. In this process, TiCh, MoOs, and Nb20s particles are mixed together and the mixture is sintered in air at a high temperature for a predetermined amount of time. When desirable, the TiCh, MoOs, and / or Nb20s particles may be replaced with a titanium, molybdenum, and / or niobium compound that will decompose to form the corresponding metal oxide(s) upon exposure to the sintering temperature.

[0057] When desirable, the method 50 may further comprise the step of milling 70 one or more of the particles of titanium oxide, molybdenum oxide, and niobium oxide in order to reduce average particle size and provide for greater homogeneity throughout the mixed oxide.

[0058] According to still another aspect of the present disclosure, a battery is provided in which the active anode material of the present disclosure is incorporated therein. Referring now to Fig. 9, this battery 75 generally comprises the active anode material 10 of the present disclosure along with an electrolyte 80. This electrolyte 80 may comprise ions 85 of lithium, sodium, or potassium. Alternatively, the ions 85 are lithium ions or sodium ions. This battery may be, without limitation, an alkaline metal ion battery.

[0059] The following specific examples are provided to further illustrate the active anode materials formed according to the teachings of the present disclosure and the method of forming these materials, as well as the properties thereof and should not be construed to limit the scope of the disclosure. Those skil led-in-the-art, in light of the present disclosure, will appreciate that many changes can be made in the specific embodiments which are disclosed herein and still obtain alike or similar result without departing from or exceeding the spirit or scope of the disclosure.

[0060] One skilled in the art will further understand that any properties reported herein represent properties that are routinely measured and can be obtained by multiple different methods. The methods described herein represent one such method and other methods may be utilized without exceeding the scope of the present disclosure.

[0061] Multiple samples of active anode materials corresponding to formula F-1 were prepared according to the method described above. Half-cells were then formed that incorporated these active anode materials and tested for their electrochemical performance. A comparison of the composition of each these active anode materials and their associated half-cell performance is provided below in Table 1 along with a comparison to a half-cell formed with a conventional TNO active anode material.

[0062] Table 1 - Reversible Specific Capacity Values Measured for Half-Cells Containing Mixed Oxide (Ti-Mo-Nb-O) Anode Materials Containing Various Ratios of TiO2, MoOs, and Nb20s with Comparison to Conventional TNO.

[0063] Experimental Parameters

[0064] The following experimental parameters were applied in the preparation and testing of each of the active anode material examples described throughout the specification.

[0065] Synthesis - TiC>2, MoOs, and Nb20s particles were mixed with the desired mass ratio by grinding the powders in a mortar and pestle for several minutes. The mixture was sintered in a muffler furnace in air at 1 ,100°C for 10-12 hours to form the active anode material. The sintered powder was sieved through a 25 micrometers (pm) stainless steel sieve prior to be dispersed in a liquid to form a slurry for future use in forming an electrode coating (anode).

[0066] Material Characterization - The structure of active anode materials is characterized through the analysis of X-ray diffraction (XRD) data. Scanning electron microscopy (SEM) or other optical or digital imaging methodology known in the art may be used to determine the shape and / or morphology of the active anode materials. The measured SEM micrographs provide images of the active anode materials at a micrometer (p.m) magnification scale.

[0067] Electrode and Cell Fabrication - Electrodes comprising each of the active anode materials were fabricated using a doctor blade coating process. A slurry was prepared by dispersing 90% of an active anode material, 5% of polyvinylidene fluoride (PVDF), and 5% C65 carbon black in N-methyl-2-pyrrolidone (NMP) using a Thinky Mixer (Thinky U.S.A. Inc., California). The slurry was applied as a thin coating via the use of the doctor blade process to an aluminum foil. The coating was dried in a vacuum oven. Then the dried coated aluminum foil was calendared and cut into small disks to form disk electrodes. After measuring the areal mass loading and electrode filmthickness, each disk electrode was assembled in a half-cell with lithium positioned as the negative electrode (cathode) and the disk electrode as the positive electrode (anode).

[0068] Cell Testing - The cell capacity measurements were performed at a C / 10 charge / discharge rate (i.e., 10-hour discharge) between 1.0 and 2.25 V vs. Li / Li+. The cycling tests were conducted at a 1C / 1C rate (charge / discharge) between 1.1 V to 3.0 V with a C / 20 tapering at 1 .1 V.

[0069] Within this specification, embodiments have been described in a way which enables a clear and concise specification to be written, but it is intended and will be appreciated that embodiments may be variously combined or separated without parting from the invention. For example, it will be appreciated that all preferred features described herein are applicable to all aspects of the invention described herein.

[0070] The foregoing description of various forms of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Numerous modifications or variations are possible in light of the above teachings. The forms discussed were chosen and described to provide the best illustration of the principles of the invention and its practical application to thereby enable one of ordinary skill in the art to utilize the invention in various forms and with various modifications as are suited to the particular use contemplated. All such modifications and variations are within the scope of the invention as determined by the appended claims when interpreted in accordance with the breadth to which they are fairly, legally, and equitably entitled.

Claims

CLAIMS1. An active anode material for use in a battery; the active anode material comprising mixed oxides of titanium, molybdenum, and niobium corresponding to the formula:TixNbyMO2-yOa wherein x, y, and a represent molar amounts with x > 0.5, y < 1 .7, x / y > 0.5, and a > 6.0.

2. The active anode material according to any of claim 1 , wherein the oxide of titanium is present in an amount corresponding to x > 1 .0.

3. The active anode material according to claims 1 and 2, wherein the oxide of titanium is present in an amount corresponding to x > 1 .5.

4. The active anode material according to claim 1 , wherein the oxide of titanium is present in an amount corresponding to 0.6 < x < 1 .6.

5. The active anode material according to claim 1 , wherein the oxide of niobium is present in an amount corresponding to y <1.5.

6. The active anode material according to claim 1 , wherein the oxide of niobium is present in an amount corresponding to 1 .3 < y <1 .7.

7. The active anode material according to claim 1 , wherein the titanium / niobium molar ratio is an amount corresponding to x / y > 0.6.

8. The active anode material according to claim 1 , wherein the titanium / niobium molar ratio is an amount corresponding to 0.5 < x / y < 1 .0.

9. The active anode material according to any of claims 1 to 8, wherein the mixed oxides of titanium, molybdenum, and niobium comprise one or more of TiO2, MoOs, and Nb20s.

10. The active anode material according to claim 1 , wherein the active anode material corresponds to the formula of Ti08Nb1.6Mo0.4O68 or Ti067Nb1.33Mo0.67O6.67.11 . The active anode material according to any of claims 1 to 10, wherein the mixed oxides further include one or more anions comprising fluorine, boron, or sulfur and / or one or more metal cations comprising a transition metal or a non-transition metal.

12. The active anode material according to claim 11 , wherein the anions comprising boron form a borate oxyanion selected from the group consisting of orthoborate BO33, metaborate BO-2, tetraborate B4O2'7, and a mixture thereof.

13. The active anode material according to any of claims 11 to 12, wherein the one or more metal cations are selected from the group consisting of zinc, copper, nickel, cobalt, vanadium, magnesium, calcium, and aluminum.

14. The active anode material according to any of claims 1 1 to 13, wherein the anions and / or metal cations in the mixed oxides are present in an amount that is less than or equal to 20 wt.% based on the overall weight of the active anode material.

15. A battery comprising an electrolyte and the active anode material according to any of claims 1 to 14.

16. The battery according to claim 15, wherein the battery is an alkaline metal ion battery.

17. The battery according to any of claims 15 to 16, wherein the electrolyte comprises lithium ions, sodium ions, or potassium ions.

18. A method of forming the active anode material according to any of claims 1 to 14, the method comprising: providing a source of titanium oxide, a source of molybdenum oxide, and a source of niobium oxide; mixing together the source of titanium oxide, the source of molybdenum oxide, and the source of niobium oxide to form a mixed oxide; and sintering the mixed oxide in the temperature range of 800°C to 1 ,350°C for a time period of 1 to 48 hours to obtain the active anode material.

19. The method according to claim 18, wherein the mixed oxide is sintered in the temperature range of 1 ,000°C to 1 ,200°C for a time period of 2 to 24 hours to obtain the active anode material.

20. The method according to any of claims 18 to 19, wherein the mixed oxide is sintered in the temperature range of 1 ,100°C to 1 ,150°C for a time period of 6 to 12 hours to obtain the active anode material.21 . The method according to any of claims 18 to 20, wherein the source of titanium oxide, the source of molybdenum oxide, and the source of niobium oxide are selected from the group consisting of particles of TiCh, MoOs, and Nb2Os, chemical compounds of titanium, molybdenum, and niobium that decompose into metal oxides at the sintering temperature, and a combination of the particles and the chemical compounds.

22. The method according to claim 21 , wherein the method further comprises the step of milling one or more of the particles of titanium oxide, molybdenum oxide, and niobium oxide to reduce average particle size.

Images