Li / Na-ion battery anode materials

Abstract

The present invention relates to an active electrode material and a method for producing the active electrode material. Such a material is of interest as an active electrode material for lithium ion batteries or sodium ion batteries. The present invention relates to a compound represented by the general formula [M1] x [M2] (1-x) [Nb] y [O] z wherein M1 and M2 are different, M1 represents one or more of Ti, Mg, V, Cr, W, Zr, Mo, Cu, Fe, Ga, Ge, Ca, K, Ni, Co, Al, Sn, Mn, Ce, Te, Se, Si, Sb, Y, La, Hf, Ta, Re, Zn, In, or Cd, M2 represents one or more of Mg, V, Cr, W, Zr, Mo, Cu, Ga, Ge, Ca, K, Ni, Co, Al, Sn, Mn, Ce, Sb, Y, La, Hf, Ta, Zn, In, or Cd, and x is 0.

Description

[Technical Field]

[0001] The present invention relates to an electrode active material and a method for producing the electrode active material. Such materials are of interest as electrode active materials for, for example, lithium-ion or sodium-ion batteries. [Background technology]

[0002] Lithium-ion (Li-ion) batteries are a commonly used type of rechargeable battery, with a global market estimated at $40 billion in 2018 and projected to grow to $200 billion by 2030. This large market is divided into various applications, ranging from transportation and utility-scale energy storage to household appliances and power tools. Therefore, rechargeable (secondary) Li-ion batteries are currently undergoing intensive research and development to improve their performance and meet industrial demand for the technology [Goodenough and Park (2013)]. In particular, Li-ion batteries are an ideal technology for electric vehicles, which meet multiple requirements from technical performance to environmental impact, providing a viable path toward a greener automotive industry.

[0003] A typical lithium-ion battery consists of multiple cells connected in series or parallel. Each cell usually consists of an anode (negative electrode) and a cathode (positive electrode), separated by a porous, electrically insulating film (called a separator) and immersed in a liquid (called an electrolyte) that allows the transport of lithium ions.

[0004] In most systems, the electrodes consist of electrochemically active materials (meaning they can chemically react with lithium ions, storing and releasing them reversibly in a controlled manner), optionally mixed with conductive additives (such as carbon) and polymeric binders. A slurry of these components is spread as a thin film onto a current collector (typically a thin foil of copper or aluminum) and allowed to dry to form the electrode.

[0005] In known Li-ion battery technologies, graphite anodes have insufficient rate capabilities during battery charging, posing a major obstacle to their application in high-power electronics, automotive, and industrial applications. Among the various alternatives recently proposed, Si, Si alloys, and lithium titanate (LTO), as well as niobium oxide-based materials, are promising candidates to replace graphite as the optimal active material for high-power applications.

[0006] Battery charging rates are usually expressed as "C-rates." A 1C charge rate means a charging current that fully charges the battery in 1 hour, while a 10C charge means the battery will fully charge in 1 / 10 of an hour (6 minutes).

[0007] Batteries relying on graphite anodes are fundamentally limited in terms of charge rate. Under nominal conditions, lithium ions intercalate into the anode active material during charging. At higher charge rates, typical graphite voltage profiles pose a high risk of overpotentially lowering the anode potential below 0 V vs. Li / Li+, resulting in lithium ions instead depositing as lithium metal on the graphite electrode surface, a phenomenon known as lithium dendrite electroplating. This results in an irreversible loss of active lithium and therefore a rapid decline in cell capacity. In some cases, these dendritic deposits can grow to such large sizes that they can penetrate the battery separator, causing a short circuit in the cell. This can trigger catastrophic cell failure, resulting in fire or explosion. As a result, the fastest-charging batteries with graphite anodes are limited to charge rates of 5–7 C, though most are lower. Despite this, graphite anodes accounted for over 90% of the Li-ion battery market in 2018.

[0008] While Si and Si alloys exhibit large specific capacities, they suffer from reduced lifetimes during high-rate charge and discharge, and poor capacity retention when the rate increases from low rates (e.g., 0.5C) to high rates (e.g., 5C). This is due to the limited diffusion rate of lithium ions within the particles, which leads to uneven lithiation of the active material particles during charging. Because the core of the active material particles (typically 1–20 μm spheres) requires lithium ions to diffuse from the particle surface to the core, there is no time for lithiation during fast charging. Therefore, increasing the charge rate can result in poor capacity retention. Furthermore, Si and Si alloy active materials physically expand by up to 400% by volume upon lithiation. As a result, uneven particle lithiation can cause mechanical stress within the particles, leading to particle splitting and electrode shattering, which can shorten the electrode's cycle life during fast charging.

[0009] Lithium titanate (LTO) anodes, due to their high potential (1.6 V vs. Li / Li+), are not susceptible to dendrite electroplating at high charge rates and exhibit excellent cycle life due to their lack of volumetric expansion caused by lithiation. For these two reasons, LTO cells are generally considered to be highly safe. However, LTO is a relatively poor electronic and ionic conductor, limiting its capacity retention at high rates unless the material is nano-sized to increase its specific surface area and carbon-coated to enhance its electronic conductivity. Such particle-level material engineering increases the cost of the material particles and reduces the tap density of the active LTO powder. This is important because it results in a lower electrode density and a higher proportion of electrochemically inactive materials (e.g., binders, carbon additives).

[0010] An important indicator of anode performance is its volumetric capacity (mAh / cm 3), i.e., the amount of charge (i.e., lithium ions) that can be stored per unit volume of the anode. This amount is a key factor in determining the overall battery energy density (Wh / L) on a volumetric basis. Volumetric capacity can be roughly calculated as the product of the electrode density, the specific capacity of the active material, and the percentage of active material in the electrode. LTO anodes typically have a relatively low specific capacity (about 170 mAh / g, compared with about 330 mAh / g for graphite), which explains the low electrode density mentioned above (typically 1.9 g / cm). 3 ) and the small proportion of active material (less than 87%), resulting in a very low volumetric capacity (300 mAh / cm 3 LTO batteries / cells have a low energy density (less than 100 kJ / kWh), which results in a low battery energy density and a high cost per kWh. As a result, LTO batteries / cells are generally limited to specific niche applications, despite their long cycle life, fast charging capabilities, and high safety.

[0011] Mixed niobium oxide (MNO) was first suggested as a potential battery material in the academic literature in the 1980s [Cava et al. (1983); Cava et al. (1984)], but interest was limited at the time due to the lack of commercially available cathodes that matched its rate capability.

[0012] In the early 2010s, practical cells combining TiNb2O7 anodes with commercially available LNMO cathodes were demonstrated, showing promising performance in terms of rate capability, cycle life, and energy density, reviving interest in MNO anodes [Goodenough and Park (2013)]. MNO anodes such as TiNb2O7 offer similar properties to LTO in that they exhibit a high operating potential (1.6 V) and low volume expansion (<5%) vs. Li / Li+, resulting in safe fast charging and long cycle life (>10,000 cycles). The main advantage of MNO anodes is that they can achieve significantly higher specific capacities than LTO (e.g., approximately 300 mAh / g for TiNb2O7), thereby improving the cell's energy density. However, MNO materials such as TiNb2O7 generally have too low electronic conductivity to sustain high charge rates without particle engineering or carbon coating, thus presenting limitations similar to those of LTO.

[0013] Meanwhile, other MNOs, such as Nb2O5, were also investigated for battery applications in the 1980s, and these generally have the so-called "Wadsley-Roth" or "bronze" crystal structure, which allows for extremely fast lithium ion diffusion rates. -14 ~10 -10 cm 2 s -1 (LTO is generally 10 -17 cm 2 s -1 ) has been recently shown to be possible to achieve a high electrode density (i.e., 2.5 g / cm) [Griffith et al. (2016)]. 3 (over 600mAh / cm 3The potential for improved cell performance (>1000kJ / s) and cell energy density in some cases is significant. However, several challenges, including low electronic conductivity, limited lifetime as a "micromaterial" (crystals approximately 1-10 μm in size), and a "gradient" lithiation voltage profile, limit the commercial deployment of these materials. The lithiation voltage profile refers to the shape of the anode potential relative to the amount of lithium inserted in the anode. While LTO and TiNb2O7 have "flat" voltage profiles, materials such as Nb2O5 generally have a "gradient" voltage profile. A voltage profile with too large a gradient results in a large voltage window, which makes full-cell balancing difficult in commercial cells.

[0014] TiNb2O7 in particular has further limitations for its application in high-power battery technology. This material has a limited Li-ion diffusion rate (8.0x10) compared to other MNOs. -16 cm 2 s -1 ), thus limiting performance at high power (other MNOs, e.g. Nb 12 MoO 33 =4.0x10 -14 cm 2 s -1 (Zhu 2019). In particular, this limits the use of pseudocapacitive charge storage mechanisms, a key advantage of MNOs at high power levels (Yang 2017).

[0015] US9515319B2 mentions TiNb2O7 and contemplates modifying this material, but does not provide examples. However, the raw materials and processes used in this disclosure are expensive (up to 50 hours 1500 o C furnace treatment), the resulting materials exhibit low initial coulombic efficiencies (84.7%, 86.5%). US2015 / 0270543A1 and KR20150131800A disclose modifying TiNb2O7.

[0016] US2019 / 0288283A1 discloses a lithium niobium composite oxide in which part of the niobium needs to be substituted by at least one element selected from Fe, Mg, Al, Cu, Mn, Co, Ni, Zn, Sn, Ti, Ta, V, and Mo as an essential feature.

[0017] The present invention has been devised in view of the above considerations.

Summary of the Invention

[0018] The inventors recognized that, despite the obvious problems presented by the prior art, it is possible to provide an active electrode material that overcomes some or all of the problems presented by the materials of the prior art above.

[0019] Thus, in a first aspect, the present invention provides an active electrode material represented by the general formula [M1] x [M2] (1-x) [Nb] y [O] z where M1 and M2 are different, M1 represents one or more of Ti, Mg, V, Cr, W, Zr, Mo, Cu, Fe, Ga, Ge, Ca, K, Ni, Co, Al, Sn, Mn, Ce, Te, Se, Si, Sb, Y, La, Hf, Ta, Re, Zn, In, or Cd, M2 represents one or more of Mg, V, Cr, W, Zr, Mo, Cu, Ga, Ge, Ca, K, Ni, Co, Al, Sn, Mn, Ce, Sb, Y, La, Hf, Ta, Zn, In, or Cd, x satisfies 0 < x < 0.5, y satisfies 0.5 ≤ y ≤ 49, and z satisfies 4 ≤ z ≤ 124.

[0020] Materials where M1 and M2 are different can also be referred to as mixed cation active materials or composite oxide active materials. These terms are used interchangeably in this disclosure to refer to materials of the general formula as shown above. Such materials are non-mixed cation active materials (e.g., general formula [M] x [Nb] y [O] zThe electrochemical properties may be improved compared to materials having M, where M represents a single ion.

[0021] In particular, as demonstrated by the examples, the inventors have found that substituting non-Nb cations to form mixed cation structures can increase entropy in the crystal structure and reduce the potential energy barrier for Li-ion diffusion by introducing small defects. Modification by creating mixed cation structures that maintain the same overall oxidation state as the unmodified crystal structure demonstrates the potential for improvement through altering the ionic radius. This modification can result in small changes to the crystal parameters and Li-ion cavities, which can improve electrochemical properties. For example, substitution with cations of larger ionic radius can enlarge the unit cell compared to the unmodified structure, resulting in faster Li-ion diffusion rates. Modification by creating mixed cation structures that result in an increased oxidation state, combined with the introduction of additional electron holes into the structure to aid electrical conductivity, offers similar potential benefits to altering the ionic radius. Modification by creating mixed cation structures that result in a decreased oxidation state, combined with the introduction of oxygen vacancies and additional electrons into the structure to aid electrical conductivity, offers similar potential benefits to altering the ionic radius. Modification by inducing oxygen vacancies from high temperature treatment under inert or reducing conditions provides a reduced structure with significantly improved conductivity. The combination of a mixed cation structure and induced oxygen vacancies enables multiple beneficial effects.

[0022] As indicated above, M1 represents one or more of Ti, Mg, V, Cr, W, Zr, Mo, Cu, Fe, Ga, Ge, Ca, K, Ni, Co, Al, Sn, Mn, Ce, Te, Se, Si, Sb, Y, La, Hf, Ta, Re, Zn, In, or Cd. M2 represents one or more of Mg, V, Cr, W, Zr, Mo, Cu, Ga, Ge, Ca, K, Ni, Co, Al, Sn, Mn, Ce, Sb, Y, La, Hf, Ta, Zn, In, or Cd. By "representing one or more of," it is intended that either M1 or M2 can each represent two or more elements from the respective list. For example, such a material may be Ti 0.05 W 0.25 Mo 0.70 Nb 12 O 33 where M1 is Ti x’ W x’’ (x'+x''=x), where M2 represents Mo, x=0.3, y=12, and z=33. Another example of such a material is Ti 0.05 Zr 0.05 W 0.25 Mo 0.65 Nb 12 O 33 where M1 is Ti x’ Zr x’’ W x’’’ (x'+x''+x'''=x), where M2 represents Mo, x=0.35, y=12, and z=33.

[0023] Optionally, M1 represents one or more of K, Mg, Ca, Y, Ti, Zr, Hf, V, Ta, Cr, Mo, W, Mn, Fe, Co, Ni, Cu, Zn, Al, Ga, Si, Ge, Sn, Sb. M1 may represent one or more of Ti, Mg, V, Cr, W, Zr, Mo, Cu, Ga, Ge, K, Ni, Al, Hf, Ta, or Zn. Preferably, M1 represents one or more of Ti, Mg, V, Cr, W, Zr, Mo, Ga, Ge, Al, or Zn.

[0024] M2 does not represent Ti. In other words, it is preferable that Ti is not the main non-Nb cation in the active electrode material. When M1 represents Ti alone, x is preferably 0.05 or less. When M1 represents one or more cations including Ti, the amount of Ti relative to the total amount of non-Nb cations is preferably 0.05:1 or less.

[0025] Optionally, M2 is selected from one or more of Mo, W, V, Zr, Al, Zn, Ga, Ge, Ta, Cr, Cu, K, Mg, Ni, or Hf. M2 may be selected from one or more of Mo, W, V, Zr, Al, Zn, Ga, or Ge. Preferably, M2 is selected from one or more of Mo, W, V, or Zr. The inventors have found that selecting M2 from one of these elements can improve the electrochemical properties of the active electrode material. M2 may be composed of a single element.

[0026] When 0 < x < 0.5 is satisfied, M2 is the main non-Nb cation in the active electrode material. Preferably, x satisfies 0.01 ≦ x ≦ 0.4, more preferably, x satisfies 0.05 ≦ x ≦ 0.25. For example, x may be about 0.05.

[0027] The exact values of y and z within the defined ranges can be selected to provide a charge-balanced or substantially charge-balanced crystal structure. Additionally or alternatively, the exact values of y and z within the defined ranges can be selected to provide a thermodynamically stable or thermodynamically metastable crystal structure.

[0028] In some cases, z may be defined in the form z = (z' - z'α), where α is a non-integer value less than 1, e.g., α satisfies 0≦α≦0.05. α may be greater than 0, i.e., α satisfies 0<α≦0.05. When α is greater than 0, the active electrode material is an oxygen-deficient material, i.e., the material has oxygen vacancies. Such materials may not have exact charge balance, but are considered "substantially charge-balanced" as described above. Alternatively, if the material is not an oxygen-deficient material, α may be equal to 0.

[0029] When α is 0.05, the number of oxygen vacancies corresponds to 5% of the total oxygen in the crystal structure. In some embodiments, α can be greater than 0.001 (0.1% oxygen vacancies), greater than 0.002 (0.2% oxygen vacancies), greater than 0.005 (0.5% oxygen vacancies), or greater than 0.01 (1% oxygen vacancies). In some embodiments, α can be less than 0.04 (4% oxygen vacancies), less than 0.03 (3% oxygen vacancies), less than 0.02 (2% oxygen vacancies), or less than 0.1 (1% oxygen vacancies). For example, α can satisfy 0.001≦α≦0.05. When a material is oxygen deficient, the electrochemical properties of the material may be improved, e.g., electrical conductivity may be improved in resistance measurements compared to an equivalent non-oxygen deficient material. As will be understood, percentages expressed herein are atomic percentages.

[0030] The oxygen deficiency in a material (e.g., expressed as a percentage of oxygen vacancies) can be measured by measuring the change in mass of a sample over time due to the re-inclusion of oxygen in the oxygen vacancies, for example, by thermogravimetric analysis (TGA) in an oxygen-rich atmosphere. Alternatively or additionally, oxygen deficiency can be measured qualitatively by assessing the color of the material relative to a non-oxygen-deficient sample of the same material. For example, non-oxygen-deficient MoNb 12 O 33 Oxygen-deficient MoNb is white, off-white, or yellow. 12 O <33 is purple. 12 O <33When oxygen-deficient crystals of are prepared, a color change from white / off-white / yellow to purple can be observed.

[0031] M1 may have the same or a lower oxidation state as M2. Preferably, M1 has a lower oxidation state than M2. When more than one element is present as M1 and / or M2, it is understood that the oxidation state refers to M1 and / or M2 as a whole. For example, if 25 at% of M1 is Ti and 75 at% of M1 is W, the oxidation state of M1 is 0.25 × 4 (contribution from Ti) + 0.75 × 6 (contribution from W). Advantageously, when M1 has a lower oxidation state than M2, this is compensated for by the formation of oxygen vacancies, i.e., an active electrode material with oxygen deficiencies is formed. The presence of oxygen vacancies is believed to improve the conductivity of the active electrode material, providing further benefits, as evidenced by the examples. Optionally, M1 includes at least one cation having a 4+ oxidation state, and M2 includes at least one cation having a 6+ oxidation state. Optionally, M1 has a 4+ oxidation state, and M2 has a 6+ oxidation state. Preferably, M1 has a different ionic radius than M2, most preferably a larger ionic radius. This results in a change in the size of the unit cell, resulting in local distortions in the crystal structure. Changing the cavity size is therefore believed to alter the availability of Li-ion sites, reducing the energy barrier to reversible lithiation and improving electrochemical properties such as specific capacity and coulombic efficiency. The ionic radius may be the Shannon ionic radius (available in RD Shannon, ActaCryst., A32, 1976, 751-76) for the coordination and valence that the ion is expected to adopt in the crystal structure of the active electrode material.

[0032] The active electrode material is (i) M1 x Mo (1-x) Nb 12 O (33-33α) M1 x W (1-x) Nb 12 O (33-33α) M1 x V (1-x) Nb9O (25-25α) M1 x Zr (1-x) Nb 24 Or (62-62α) M1 x W (1-x) Nb 0.57 Or (4.43-4.43α) M1 x W (1-x) Nb 0.89 Or (5.22-5.22α) M1 x Zn (1-x) Nb 17 Or (43.5-43.5α) M1 x Cu (1-x) Nb 17 Or (43.5-43.5α) M1 x Al (1-x) Nb 11 Or (29-29α) M1 x Yes (1-x) Nb 11 Or (29-29α) M1 x Gee (1-x) Nb 18 Or (47-47α) M1 x W (1-x) Nb 1.125 Or (5.81-5.81α) M1 x W (1-x) Nb 3.2 Or (11-11α) M1 x Al (1-x) Nb 49 Or (124-124α) M1 x Yes (1-x) Nb 49 Or (124-124α) 、 or (ii)M1 x You (1-x) Nb 12 Or (33-33α) M1x W (1-x) Nb 12 O (33-33α) M1 x V (1-x) NbO (25-25α) M1 x Zr (1-x) Nb 24 O (62-62α) M1 x W (1-x) Nb 0.57 O (4.43-4.43α) M1 x W (1-x) Nb 0.89 O (5.22-5.22α) M1 x Zn (1-x) Nb 17 O (43.5-43.5α) M1 x Al (1-x) Nb 11 O (29-29α) M1 x Ge (1-x) Nb 18 O (47-47α) , or preferably (iii) M1 x Mo (1-x) Nb 12 O (33-33α) M1 x W (1-x) Nb 12 O (33-33α) M1 x V (1-x) NbO (25-25α) M1 x Zr (1-x) Nb 24 O (62-62α) M1 x W (1-x) Nb 0.57 O (4.43-4.43α) M1 x W (1-x) Nb 0.89 O (5.22-5.22α) and may be a material selected from the group consisting of M1 represents one or more of Ti, Mg, V, Cr, W, Zr, Mo, Cu, Fe, Ga, Ge, Ca, K, Ni, Co, Al, Sn, Mn, Ce, Te, Se, Si, Sb, Y, La, Hf, Ta, Re, Zn, In, or Cd, x satisfies 0 < x < 0.5, and α satisfies 0 ≤ α ≤ 0.05.

[0033] In a particularly preferred embodiment, the active electrode material is M1 x Mo (1-x) Nb 12 O (33-33α) is. In another particularly preferred embodiment, the active electrode material is M1 x W (1-x) Nb 0.57 O (4.43-4.43α) is. In another particularly preferred embodiment, the active electrode material is M1 x Zn (1-x) Nb 17 O (43.5-43.5α) is. In another particularly preferred embodiment, the active electrode material is M1 x Al (1-x) Nb 11 O (29-29α) is. The examples show that these materials have particularly advantageous properties for use as active electrode materials.

[0034] The above materials in groups (i), (ii), and (iii), and in particularly preferred embodiments, represent certain non-mixed cationic active materials (i.e., when x = 0) modified to mixed cationic active materials by substitution of less than half of M2 by different elements M1. Optionally, in these materials, M2 may also be substituted by Nb on non-Nb sites of the crystal structure. That is, M1 can represent one or more of Ti, Mg, V, Cr, W, Zr, Mo, Cu, Fe, Ga, Ge, Ca, K, Ni, Co, Al, Sn, Mn, Ce, Te, Se, Si, Sb, Y, La, Hf, Ta, Re, Zn, In, Cd, or Nb. M1 can also represent a further list of elements described above and in the claims.

[0035] In a second embodiment, the present invention is [M][Nb] y [O]z wherein the active electrode material is oxygen deficient, M is Mg, Cr, W, Mo, Cu, Ga, Ge, Ca, K, Ni, Co, Al, Sn, Mn, Ce, Sb, Y, La, Hf, Ta, Zn, In, or Cd, y satisfies 0.5≦y≦49, and z satisfies 4≦z≦124.

[0036] The material according to the second aspect of the invention is MoNb 12 O 33 , WNb 12 O 33 , W7Nb4O 31 , and W9Nb8O 47 The oxygen-deficient material according to the second aspect of the invention is an oxygen-deficient analog of a known "parent" material such as α. z may be defined as z = (z' - z'α), with α satisfying 0 < α ≤ 0.05. The comments made above with respect to the material according to the first aspect specifying the possible range of α when z is defined as z = (z' - z'α), also apply here to the material according to the second aspect of the invention. For example, α may satisfy 0.001 ≤ α ≤ 0.05. The oxygen-deficient material according to the second aspect has been found to have improved properties for use as an active electrode material compared to stoichiometric "parent" materials. For example, the material according to the second aspect has improved electrical conductivity.

[0037] M may consist of one of Mo, W, Al, Zn, Ga, Ge, Ta, Cr, Cu, K, Mg, Ni, or Hf, or M may consist of one of Mo, W, Al, Zn, Ga, or Ge. Preferably, M may consist of one of Mo, W, Al, or Zn.

[0038] The active electrode material of the second embodiment has the general formula [M] selected from the group consisting of: x [Nb] y [O] (z’-z’α) It can be expressed as:

[0039] MoNb 12 O (33-33α) WNb 12 O (33-33α) W7Nb4O(31-31α) W9Nb8O (47-47α) Zn2Nb 34 O (87-87α) Cu2Nb 34 O (87-87α) AlNb 11 O (29-29α) GaN 11 O (29-29α) GeNb 18 O (47-47α) W 16 Nb 18 O (93-93α) W5Nb 16 O (55-55α) AlNb 49 O (124-124α) GaN 49 O (124-124α) However, α satisfies 0<α≦0.05.

[0040] These are specific stoichiometric mixed niobium oxides modified to oxygen-deficient mixed niobium oxides.

[0041] The active electrode material of the second embodiment has the general formula [M] selected from the group consisting of: x [Nb] y [O] (z’-z’α) It can be expressed as:

[0042] MoNb 12 O (33-33α) WNb 12 O (33-33α) W7Nb4O (31-31α) W9Nb8O (47-47α) Zn2Nb 34 O (87-87α) AlNb 11 O (29-29α) GeNb 18 O(47-47α) However, α satisfies 0<α≦0.05.

[0043] The active electrode material of the second embodiment has the general formula [M] selected from the group consisting of: x [Nb] y [O] (z’-z’α) It can be expressed as:

[0044] MoNb 12 O (33-33α) WNb 12 O (33-33α) W7Nb4O (31-31α) W9Nb8O (47-47α) However, α satisfies 0<α≦0.05.

[0045] Optionally, M is W, i.e., the active electrode material has the general formula [W][Nb] y [O] z For example, the active electrode material may be WNb 12 O (33-33α) , W7Nb4O (31-31α) , W9Nb8O (47-47α) , W 16 Nb 18 O (93-93α) , and W5Nb 16 O (55-55α) The examples show that inducing oxygen vacancies in several different tungsten niobium oxides results in improved properties, such as improved electrical conductivity, compared to the stoichiometric base oxides.

[0046] In a particularly preferred embodiment, the active electrode material is MoNb 12 O (33-33α) In another particularly preferred embodiment, the active electrode material is WNb 12 O (33-33α) In another particularly preferred embodiment, the active electrode material is W5Nb 16 O (55-55α) In another particularly preferred embodiment, the active electrode material is WNbO (31-31α)In another particularly preferred embodiment, the active electrode material is ZnNb 34 O (87-87α) In another particularly preferred embodiment, the active electrode material is AlNb 11 O (29-29α) The examples show that these materials have particularly advantageous properties for use as active electrode materials.

[0047] The inventors have demonstrated that MoNb oxides can be produced by either incorporating multiple non-Nb cations to form mixed cation / composite oxide active materials (as in the first aspect of the present invention) and / or by creating oxygen vacancies (as in the second aspect of the present invention). 12 O 33 , WNb 12 O 33 , ZrNb 24 O 62 , VNb9O 25、 W7Nb4O 31 , and W9Nb8O 47 We have found that by modifying materials such as these, we can create active electrode materials with improved electrochemical properties, particularly when used as anode materials.

[0048] The specific capacity / reversible delithiation capacity of active electrode materials according to the present invention can be 200 mAh / g or greater, 225 mAh / g or greater, 250 mAh / g or greater, and up to about 300 mAh / g or greater, where specific capacity is defined as measured on the second cycle of a half-cell galvanostatic cycling test at a rate of 0.05 C in a voltage window of 1.1 to 3.0 V vs. Li / Li+. Providing materials with high specific capacity can be advantageous because they can provide improved performance in electrochemical devices containing the active electrode material.

[0049] Additionally, the active electrode material according to the present invention may have a suitable voltage profile as measured on the second cycle of a half-cell galvanostatic cycling test at a rate of 0.05 C with a voltage window of 1.1 to 3.0 V vs. Li / Li+. That is, the capacity of the material may be between 2.0 V and 1.1 V when lithiated >180 mAh / g, and the capacity of the material may be between 1.1 V and 2.0 V when delithiated >180 mAh / g.

[0050] When formulated or coated as an electrode (optionally with conductive carbon additives and binder materials), the bulk resistivity of the active electrode material according to the present invention may be 5 kΩ·cm or less, more preferably 2 kΩ·cm or less. Bulk resistivity is useful as a surrogate measure of the electronic conductivity of such materials. Providing a material with a suitably low bulk resistivity may be advantageous, as it can provide improved performance in electrochemical devices that include the active electrode material.

[0051] The direct current internal resistance (DCIR) and resulting area specific impedance (ASI) of the active electrode material when measured in a Li-ion half coin cell with the listed electrodes is less than 90 Ω (for DCIR) and 170 Ω.cm 2 or less (in the case of ASI). Providing a material with a suitably low DCIR and / or ASI can be advantageous, as it can provide improved performance in electrochemical devices that include the active electrode material. However, further improvements in DCIR / ASI values ​​may be seen when the active electrode material is incorporated into a commercial power cell having a cathode, for example, with a carbon-coated active electrode material, or an electrode that has been calendered and prepared in a typical known manner. When measured in such an arrangement in a coin cell, the inventors have found that the ASI can be, for example, 26 Ω.cm. 2 It is theorized that this may be the case.

[0052] The active electrode material according to the present invention is -14 cm 2 s -1Providing a material with a suitably high lithium diffusion rate can be advantageous as it can provide improved performance in electrochemical devices that include the active electrode material.

[0053] The active electrode material of the present invention has an electrode density of 2.5 g / cm after calendaring. 3 For example, the electrode density after the calendaring treatment may be up to 3.0 g / cm 3 The above has been achieved. Providing a material with such an electrode density can be advantageous because it can provide improved performance in electrochemical devices that include the active electrode material. Specifically, when the electrode density is high, a high volumetric capacity can be obtained because gravimetric capacity x electrode density x active material fraction = volumetric capacity.

[0054] The initial coulombic efficiency of the active electrode material according to the present invention may be greater than 88%, more preferably greater than 90%. In some cases, the initial coulombic efficiency of the active electrode material may be as high as 92% or greater, 93% or greater, or even 94% or greater. Providing a material with a suitably high initial coulombic efficiency can be advantageous because it can provide improved performance in electrochemical devices containing the active electrode material. The initial coulombic efficiency can be measured as the difference between the lithiation and delithiation capacities in the first charge / discharge cycle at C / 10 in a half cell.

[0055] Further optional features of the first and second aspects of the invention are set out below.

[0056] The crystalline structure of the active electrode material of the first embodiment, as determined by X-ray diffraction, may correspond to the crystalline structure of the active electrode material in its unmodified form, the unmodified form having the formula [M2][Nb] y [O] z where M2 consists of a single element and the unmodified form is not oxygen deficient. I NbO 13 , M2 I 6Nb 10.8 O30 M2 II Nb2O6, M2 II 2Nb 34 O 87 M2 III Nb 11 O 29 M2 III Nb 49 O 124 (M2 III 0.5 Nb 24.5 O 62 )、M2 IV Nb 24 O 62 M2 IV Nb2O7, M2 IV 2Nb 10 O 29 M2 IV 2Nb 14 O 39 M2 IV Nb 14 O 37 M2 IV Nb6O 17 M2 IV Nb 18 O 47 M2 V Nb9O 25 M2 V 4Nb 18 O 55 M2 V 3Nb 17 O 50 M2 VI Nb 12 O 33 M2 VI 4Nb 26 O 77 M2 VI 3Nb 14 O 44 M2 VI 5Nb 16 O 55 M2 VI 8Nb 18 O 69 M2 VI Nb2O8, M2 VI 16 Nb 18 O 93 M2 VI 20 Nb 22 O 115, M2 VI 9NbO 47 , M2 VI 82 Nb 54 O 381 , M2 VI 31 Nb 20 O 143 , M2 VI 7NbO 31 , M2 VI 15 NbO 50 , M2 VI 3NbO 14 , and M2 VI 11 Nb 12 O 63、 where the numbers I, II, III, IV, V, and VI represent the oxidation states of M2. In this way, it is possible to identify the unmodified form as being modified without significantly affecting the crystal structure.

[0057] The crystalline structure of the active electrode material of the second embodiment, as determined by X-ray diffraction, may correspond to the crystalline structure of the active electrode material in its unmodified form, which has the general formula [M][Nb] y [O] z The unmodified form is not oxygen deficient, and the unmodified form is represented by M2 I NbO 13 , M2 I 6Nb 10.8 O 30 , M2 II Nb2O6, M2 II 2Nb 34 O 87 , M2 III Nb 11 O 29 , M2 III Nb 49 O 124 , M2 IV Nb 24 O 62 , M2 IV Nb2O7, M2 IV 2Nb 10 O 29 , M2 IV 2Nb 14 O 39 , M2 IVNb 14 O 37 、M2 IV Nb6O 17 、M2 IV Nb 18 O 47 、M2 V Nb9O 25 、M2 V 4Nb 18 O 55 、M2 V 3Nb 17 O 50 、M2 VI Nb 12 O 33 、M2 VI 4Nb 26 O 77 、M2 VI 3Nb 14 O 44 、M2 VI 5Nb 16 O 55 、M2 VI 8Nb 18 O 69 、M2 VI Nb2O8、M2 VI 16 Nb 18 O 93 、M2 VI 20 Nb 22 O 115 、M2 VI 9Nb8O 47 、M2 VI 82 Nb 54 O 381 、M2 VI 31 Nb 20 O 143 、M2 VI 7Nb4O 31 、M2 VI 15 Nb2O 50 、M2 VI 3Nb2O 14 、及びM2 VI 11 Nb 12 O 63where the numbers I, II, III, IV, V, and VI represent the oxidation states of M. In this way, it is possible to identify the unmodified form as having been modified without significantly affecting the crystal structure.

[0058] The crystalline structure of the active electrode material, as determined by X-ray diffraction analysis, is (i) MoNb 12 O 33 WNb 12 O 33 VNb9O 25 ZrNb 24 O 62 W7Nb4O 31 W9Nb8O 47 Zn2Nb 34 O 87 Cu2Nb 34 O 87 AlNb 11 O 29 GaN 11 O 29 GeNb 18 O 47 W 16 Nb 18 O 93 W5Nb 16 O 55 AlNb 49 O 124 GaN 49 O 124 ,or (ii) MoNb 12 O 33 WNb 12 O 33 VNbO 25 ZrNb 24 O 62 W4Nb7O31 W9Nb8O 47 Zn2Nb 34 O 87 AlNb 11 O 29 GeNb 18 O 47 , or preferably (iii) MoNb 12 O 33 WNb 12 O 33 ZrNb 24 O 62 VNbO 25 W7Nb4O 31 W9Nb8O 47 The crystal structure of the compound may correspond to one or more of the following:

[0059] Here, the term "corresponding" means that the peaks identified by X-ray diffraction analysis of the active electrode material correspond to those of a reference crystal structure (e.g., MoNb 12 O 33、 WNb 12 O 33、 ZrNb 24 O 62、 VNbO 25、 W7Nb4O 31 , and / or W9Nb8O 47 ), preferably the crystal structure of the active electrode material does not correspond to the crystal structure of TiNb2O7, and preferably the measured XRD diffraction pattern of the active electrode material does not correspond to JCPDS Crystallographic Database Registration 00-039-1407 for TiNb2O7. Optionally, the crystal structure of the active electrode material may be shifted by 0.5 degrees or less (preferably by 0.2 degrees or less, more preferably by 0.1 degrees or less) from the corresponding peak in one or more X-ray diffraction analyses of TiNb2O7. 10 O 29 Optionally, the crystal structure of the active electrode material does not correspond to the crystal structure of M III Nb 11 O29 , for example, FeNb 11 O 29 , GaNb 11 O 29 , CrNb 11 O 29 , and AlNb 11 O 29 does not correspond to the crystal structure of

[0060] At least a portion of the active electrode material may have a Wadsley-Roth crystal structure and / or a tetragonal tungsten bronze (TTB) crystal structure. Preferably, a majority of the active electrode material has the Wadsley-Roth crystal structure and / or a tetragonal tungsten bronze (TTB) crystal structure; for example, at least 50%, at least 60%, at least 70%, at least 80%, or at least 90% by volume of the active electrode material may have the Wadsley-Roth crystal structure and / or a tetragonal tungsten bronze (TTB) crystal structure. In a preferred embodiment, substantially all of the active electrode material may have the Wadsley-Roth crystal structure and / or a tetragonal tungsten bronze (TTB) crystal structure. When a material has such a crystal structure, the material may have improved electrochemical properties.

[0061] The crystal formula of the thermodynamically stable Wadsley-Roth crystal structure in charge equilibrium is as follows:

[0062] (1) (M1, M2, M3, ...) mnp+1 O 3mnp-(m+n)p+4 In the formula, O is oxygen (anion) and M (cation) is any combination of elements selected from Ti, Mg, V, Cr, W, Zr, Nb, Mo, Cu, Fe, Ga, Ge, Ca, K, Ni, Co, Al, Sn, Mn, Ce, Te, Se, Si, Sb, Y, La, Hf, Ta, Re, Zn, In, and Cd. In the material according to the present invention, at least one of (M1, M2, M3...) consists of Nb.

[0063] Equation (1) is based on crystalline topography, where m and n are the dimensions of the edge-sharing superstructure blocks formed, ranging from 3 to 5 (integers). At the corners, the blocks are connected to infinite ribbons (p=∞) only by edge sharing, to pairs (p=2) by partial edge sharing and partial tetrahedra, or to isolated blocks (p=1) only by tetrahedra. When p is infinite, the equation becomes:

[0064] (2) (M1, M2, M3, ...) mn O 3mn-(m+n) Equations (1) and (2) together define the complete compositional sample for the Wadsley-Roth crystal structure. Preferably, the entire crystalline composition should also be charge-neutral and thermodynamically favorable.

[0065] Further information can be found in the work of Griffith et al. (2017).

[0066] References in this disclosure to the tetragonal tungsten bronze (TTB) crystal structure (or simply "bronze" structure) refer to a tetragonal tungsten bronze (TTB) structure with partially filled tunnels. As described in Montemayor 1998, such a phase is a framework of corner-sharing NbO6 octahedra interconnected to form three-, four-, and five-sided tunnels. The numerous pentagonal tunnels are filled with W, Nb, O, or appropriate metal cations to form the structure.

[0067] The active electrode material may further contain Li and / or Na. In other words, the active electrode material may be a lithiated and / or sodiated active electrode material. The active electrode material of the first embodiment has the general formula [Li] λ [M1] x [M2] (1-x) [Nb] y [O] z or [Na] λ [M1] x [M2] (1-x) [Nb] y[O] z The active electrode material of the second embodiment is represented by the general formula [Li] λ [M][Nb] y [O] z or [Na] λ [M][Nb] y [O] z where x, y, and z satisfy the ranges described above, and λ is selected to provide a charge-balanced or substantially charge-balanced crystal structure, and / or a thermodynamically stable or thermodynamically metastable crystal structure.

[0068] The active electrode material is 0.1 to 100 m 2 / g, or 0.5 to 50 m 2 / g, or 1 to 20 m 2 The active electrode material can have a BET surface area in the range of 0.1 / g. Generally, a small BET surface area is desirable to minimize reactions between the active electrode material and the electrolyte, for example, to minimize the formation of a solid-electrolyte interphase (SEI) layer during the first charge-discharge cycles of an electrode made from this material. However, if the BET surface area is too small, the bulk of the active electrode material will be inaccessible to metal ions in the surrounding electrolyte, resulting in unacceptably low charge rates and capacities. BET surface area is the surface area per unit mass calculated from measurements of the physical adsorption of gas molecules on a solid surface using the Brunauer-Emmett-Teller theory. For example, BET surface area can be determined in accordance with ISO 9277:2010.

[0069] The active electrode material may contain multiple primary crystallites (sometimes called microcrystals or crystallites). The average diameter of the primary crystallites may be between 10 nm and 10 μm, preferably between 100 nm and 5 μm, although the most desirable diameter of the primary crystallites may depend on their intended application. For example, if the active electrode material is intended for use in ultra-high power products, it may be advantageous for the primary crystallite size to be low, e.g., 50 nm or less, or 30 nm or less. If the active electrode material is to be used in the development of "high-energy power cells," it may be advantageous for the crystallite size to be larger, e.g., 5 μm or more, or 7 μm or more.

[0070] Some or all of these primary crystallites may be aggregated into secondary particles. Alternatively, the primary crystallites may be substantially non-aggregated. If some or all of these primary crystallites are aggregated into secondary particles, the average diameter of the secondary particles (e.g., D as measured using solid-state powder laser diffraction) may be less than the average diameter of the secondary particles (e.g., D as measured using solid-state powder laser diffraction). 50 The diameter of the secondary particles is 1 μm to 30 μm, preferably 2 μm to 15 μm, although the most desirable diameter of the secondary particles may depend on their intended use. For example, if the active electrode material is intended for use in ultra-high power products, it may be advantageous for the secondary particle size to be low, e.g., 4 μm or less, 2 μm or less, or 1.5 μm or less. If the active electrode material is used in the development of "high energy power cells," it may be advantageous for the secondary particle size to be larger, e.g., 8 μm or more, 12 μm or more, or 15 μm or more. The secondary particles may also be porous.

[0071] The average diameter of the primary crystallites and / or secondary particles can be measured using any conventional known technique, for example, by using SEM imaging to examine a sample of the material, selecting a number (n) of primary crystallites and / or secondary particles, and calculating the average diameter as the average diameter of the n measured primary crystallites / secondary particles, where n is, for example, 30.

[0072] Another method for measuring secondary particle size is to use solid powder laser diffraction, for example, a Horiba laser diffraction particle analyzer for dry powders with air pressure maintained at 0.3 MPa.

[0073] The active electrode material has a D as measured using solid powder laser diffraction of at least 0.05 μm, or at least 0.1 μm, or at least 0.5 μm, or at least 1 μm. 10 It may have a secondary particle diameter D 10 Maintaining particle size within these ranges reduces the potential for parasitic reactions in Li-ion cells due to reduced surface area, requires less binder in the electrode slurry, and facilitates processing. n" refers to the diameter below which n% of the particle population by volume is found.

[0074] The active electrode material has a D of less than 50 μm, less than 20 μm, less than 10 μm, or less than 5 μm as measured using solid-state powder laser diffraction. 90 It may have a secondary particle size. 90 By maintaining the particle size within these ranges, the proportion of the particle size distribution having large particle sizes is minimized, facilitating the fabrication of the material into a homogeneous electrode.

[0075] The active electrode material may include a carbon coating formed on the surface of the primary crystallites and / or secondary particles. Several suitable methods for forming a carbon coating on the surface of the primary crystallites and / or secondary particles are described in the literature, for example, Zhou (2012). Other suitable methods are described below. The carbon coating may be present in an amount of up to 5 wt. % based on the total weight of the active electrode material. The carbon coating may include graphitic carbon.

[0076] When the active electrode has the form of a plurality of primary crystallites, some or all of which are aggregated into porous secondary particles, the secondary particles may include a coating of carbon formed on at least the surfaces of the pores of the secondary particles.

[0077] In a third aspect, the present invention provides an electrochemical device comprising an anode, a cathode, and an electrolyte disposed between the anode and the cathode, wherein the anode comprises an electrode active material according to the first or second aspect of the present invention.

[0078] The electrolyte may be a liquid electrolyte. Alternatively or additionally, the electrolyte may be a solid-state electrolyte.

[0079] The anode can further include a conductive additive and / or a binder. For example, the anode can have a composition of about 80% by weight active material, about 10% by weight conductive additive, and about 10% by weight binder. Alternatively, the anode can have a composition of about 91% by weight active material, about 5% by weight conductive additive, and about 4% by weight binder. The amount of active electrode material in the anode can range from 70% to 99% by weight, more preferably from 75% to 98% by weight, and even more preferably from 85% to 96% by weight.

[0080] In a fourth aspect, the present invention provides a method of using an electrode active material according to the first or second aspect of the present invention (i) as an anode active material, or a component of an anode active material, in an anode, in combination with a cathode and electrolyte of a lithium-ion battery for charging and discharging the lithium-ion battery, or (ii) as an anode active material, or a component of an anode active material, in combination with a cathode and electrolyte of a sodium-ion battery for charging and discharging the sodium-ion battery.

[0081] In a fifth aspect, the present invention provides a method of processing an electrode active material according to the first or second aspect of the invention (i) as or into an anode active material for a lithium-ion battery, the method comprising diffusing lithium ions into the anode active material, or a method of processing an electrode active material according to the first or second aspect of the invention (ii) as or into an anode active material for a sodium-ion battery, the method comprising diffusing sodium ions into the anode active material.

[0082] In a sixth aspect, the present invention provides a method for producing an active electrode material according to the first or second aspect of the present invention, the method comprising the steps of providing one or more precursor materials; mixing the precursor materials to form a precursor material mixture; and heat-treating the precursor material mixture at a temperature in the range of 400°C to 1350°C to form the active electrode material.

[0083] Where it is desired to make a material according to the first aspect of the present invention, preferably the one or more precursor materials comprise a source of M1 ions, a source of M2 ions, and a source of Nb.

[0084] Where it is desired to make a material according to the second aspect of the present invention, preferably the one or more precursor materials comprise a source of M and a source of Nb.

[0085] The phrase "M ion source" is used herein to describe a material that includes M ions / atoms. The phrase "M ion source" is used herein to describe a material that includes M ions / atoms. For example, the phrase "source of Mo / W / Zr / V / Nb" is used to describe a material that includes Mo / W / Zr / V / Nb ions / atoms, as appropriate.

[0086] The precursor material can include one or more metal oxides, metal hydroxides, metal salts, or oxalates. For example, the precursor material can include one or more metal oxides of different oxidation states and / or different crystal structures. Examples of suitable metal oxide precursor materials include Nb2O5, NbO2, WO3, TiO2, MoO 3、 Examples of precursor materials include, but are not limited to, V2O5, ZrO2, and MgO. However, the precursor material may not include a metal oxide or may include an ion source other than an oxide. For example, the precursor material may include a metal salt (e.g., NO3 - , SO3 - ) or other compounds (e.g., oxalates). Preferably, the one or more precursor materials include one or more of a Nb source, a Mo source, a W source, a Zr source, and / or a V source.

[0087] Some or all of the precursor material may be particulate material. If particulate, it preferably has an average particle size of less than 20 μm in diameter (e.g., D as measured using solid-state powder laser diffraction). 50diameter). The average particle size may be, for example, in the range of 10 nm to 20 μm. Providing particulate materials with such average particle sizes can help promote more intimate mixing of the precursor materials, thereby resulting in a more efficient solid-state reaction during the heat treatment step. However, it is not necessary for the precursor materials to have an initial particle size of less than 20 μm, since the particle size of one or more precursor materials can be mechanically reduced during the step of mixing the precursor materials to form the precursor material mixture.

[0088] The step of mixing / milling the precursor materials to form a precursor material mixture can be performed by a process selected from, but not limited to, dry or wet planetary ball milling, rolling ball milling, high-shear milling, air-jet milling, and / or impact milling. The force used for mixing / milling can depend on the morphology of the precursor materials. For example, if some or all of the precursor materials have larger particle sizes (e.g., average particle sizes greater than 20 μm in diameter), the milling force can be selected to reduce the average particle size of the precursor materials such that the average particle size of the precursor material mixture is reduced to 20 μm or less in diameter. Having an average particle size of 20 μm or less in the precursor mixture can more efficiently promote solid-state reaction of the precursor materials in the precursor mixture during the heat-treatment step.

[0089] The step of heat-treating the precursor material mixture can be carried out for a time period of 1 to 24 hours, more preferably 3 to 14 hours. For example, the heat-treating step can be carried out for 1 hour or more, 2 hours or more, 3 hours or more, 6 hours or more, or 12 hours or more. The heat-treating step can be carried out for 24 hours or less, 18 hours or less, 14 hours or less, or 12 hours or less.

[0090] In some methods, it may be beneficial to perform a two-step heat treatment. For example, the precursor material mixture can be heated at a first temperature for a first time, followed by heating at a second temperature for a second time. Preferably, the second temperature is higher than the first temperature. Such a two-step heat treatment can aid in the solid-state reaction to form the desired crystalline structure.

[0091] The step of heat-treating the precursor material mixture can be carried out in a gas atmosphere. The gas atmosphere can be an inert atmosphere or a reducing atmosphere. If it is desired to produce an oxygen-deficient material, the step of heat-treating the precursor material mixture is preferably carried out in an inert atmosphere or a reducing atmosphere. Suitable gas atmospheres include air, N2, Ar, He, CO2, CO, O2, H2, and mixtures thereof.

[0092] The method may include one or more post-treatment steps after formation of the active electrode material.

[0093] In some cases, the method may include a post-treatment step, sometimes referred to as "annealing," of heat-treating the active electrode material. This post-treatment heat-treatment step may be performed in a different gas atmosphere than the step of heat-treating the precursor material mixture to form the active electrode material. The post-treatment heat-treatment step may be performed in an inert or reducing gas atmosphere. Such a post-treatment heat-treatment step may be performed at a temperature greater than 500°C, e.g., about 900°C. The inclusion of a post-treatment heat-treatment step may be beneficial, for example, to form defects or imperfections in the active electrode material, e.g., to form oxygen vacancies. Preferably, a post-treatment heat-treatment step performed in an inert or reducing gas atmosphere may improve the electrical conductivity of the active electrode material. This may result in the synthesis of an active electrode material according to the second aspect.

[0094] In some cases, the method may include a post-treatment step of mixing the active electrode material with a carbon source, thereby forming a carbon coating on the active electrode material. Optionally, the mixture of the active electrode material and the carbon source may be heated to form a carbon coating on the active electrode material. Suitable carbon sources include, but are not limited to, carbohydrate materials (e.g., sugars, polymers), conductive carbon (e.g., carbon black), and / or aromatic carbon materials (e.g., pitch carbon).

[0095] One preferred method of forming the carbon coating involves grinding the active electrode material with a carbon source, and then pyrolyzing the active electrode material and the carbon source under an inert or reducing atmosphere (e.g., in a furnace).

[0096] Another preferred method for forming the carbon coating involves mixing the active electrode material with a carbon source, dispersing the active electrode material and the carbon source in an aqueous slurry, and then spray-drying. The resulting powder may optionally be pyrolyzed. If the carbon source is conductive carbon black or the like, pyrolysis after spray-drying is not necessary.

[0097] In some cases, the method may include a post-processing step in which the active electrode material is milled to modify the particle size of the active electrode material. For example, the active electrode material may be processed by one or more processes including air jet milling, impact milling, high shear milling, sieving, or ball milling. This may provide a particle size more suitable for use in the desired application of the active electrode material.

[0098] In a further aspect, the present invention provides the use of a dopant M1 to improve the properties of a host material for use as an active material in a metal-ion battery anode, wherein the host material has a structure of M2Nb y O z and the dopant is the modified material [M1] x [M2] (1-x) [Nb] y [O] zThe modified material has improved properties compared to the base material. The improved properties can be improved initial coulombic efficiency (exemplified as the difference between lithiation and delithiation capacities in the first charge / discharge cycle at C / 10 in a half cell). The improved properties can be improved capacity retention at high rate charge / discharge compared to low rate (exemplified as 5C or 10C versus 0.5C). The improved properties can also be improved specific capacity at low charge / discharge rates (exemplified herein at 0.1C). M1, M2, x, y, and z are as defined herein.

[0099] The present invention includes combinations of the above-described aspects and features and preferred features, except where such combinations are expressly not permitted or explicitly avoided.

[0100] Next, embodiments and experiments illustrating the principles of the present invention will be described with reference to the accompanying drawings. [Brief explanation of the drawings]

[0101]

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[0102] Aspects and embodiments of the present invention will now be described with reference to the accompanying drawings. Further aspects and embodiments will become apparent to those skilled in the art. All documents mentioned in this text are incorporated herein by reference.

[0103] Many different materials were prepared and characterized, as summarized below in Table 1. These samples can be broadly divided into several groups.

[0104] Samples 1, 2, 3, 4, 5, 14, 15, 16, 18, and 22 are MoNb 12 O 33 (M 6+ Nb 12 O 33 It belongs to the Wadsley-Roth family of phases based on a 3x4 block of octahedra with a tetrahedron at each corner of each block. The blocks are formed by edge sharing between NbO6 octahedra and M 6+ The NbO4 tetrahedra and NbO6 octahedra are connected to each other by corner sharing between them. Sample 1 is the parent crystal structure, which has been modified to a mixed metal cation structure by exchanging one or more cations in samples 2-4, and / or to an isostructural WNbO structure in samples 14, 15, 16, 18, and 22. 12 O 33 The crystals are modified to a mixed crystal configuration (mixed with cations). Sample 5 has oxygen deficiencies in the parent crystal and mixed metal cation structure 18. Sample 3 is a spray-dried and carbon-coated version of the crystals produced in Sample 2, and Sample 22 is a spray-dried and carbon-coated version of the crystals produced in Sample 16.

[0105] Samples 6, 7, 17, 19, and 20 are ZrNb 24 O 62 (M 4+ Nb 24 O 62 It belongs to the Wadsley-Roth family of phases based on a 3x4 octahedral block with half tetrahedrons at the corners of each block.

[0106] Samples 8, 9, and E11 are WNb12 O 33 (M 6+ Nb 12 O 33 It belongs to the Wadsley-Roth family of phases based on a 3x4 NbO6 octahedral block with a tetrahedron at each block corner.

[0107] Samples 10, 11, and 21 are VNbO 25 (M 5+ NbO 25 It belongs to the Wadsley-Roth family of phases based on a 3x3 NbO6 octahedral block with a tetrahedron at each block corner).

[0108] Samples 12, 13, and E14 are WNbO 31 (M 6+ 7NbO 31 It belongs to the family of tungsten tetragonal bronze (TTB) based on Nb. It has a tetragonal tungsten bronze structure in which MO6 (M = 0.4Nb + 0.6W) octahedra share only corners with tunnels having 3, 4, and 5 sides. Some of these tunnels are filled with -OMO- chains, while others are open for the transport and storage of lithium ions.

[0109] Samples E1, E2, and E13 are Zn2Nb 34 O 87 (M 2+ 2Nb 34 O 87 ) based on the Wadsley-Roth phase. This orthorhombic phase is composed of 3x4 MO6 octahedra (M=Zn +2 / Nb +5 ) blocks, which are connected only by shared edges and have no tetrahedra.

[0110] Samples E3, E4, E5, and E12 are AlNb 11 O 29 (M 3+ Nb 11 O 29It belongs to the family of Wadsley-Roth phases based on the hexagonal hexagonal structure. This structure is a monoclinic shear structure consisting of 3 × 4 octahedral blocks joined only by edge-sharing, with no tetrahedra.

[0111] Samples E6, E7, and E8 are GeNb 18 O 47 (M 4+ Nb 18 O 47 ) based Wadsley-Roth phase. This structure is similar to sample 10, which has a 3x3 NbO6 octahedral block and one tetrahedron connecting the blocks at the corners. However, this structure is different from that of sample 10, which has a V 5+ Instead of Ge +4 This includes intrinsic defects caused by

[0112] Samples E9 and E10 are W5Nb 16 O 55 (M 6+ 5Nb 16 O 55 It belongs to the family of Wadsley-Roth phases based on (W,Nb)O. The structure is made up of 4x5 blocks connected laterally by edge-sharing (W,Nb)O6 and at the corners by WO4 tetrahedra. The structure is similar to samples 8 and 9, but with larger block sizes.

[0113] [Table 1]

[0114] material synthesis The samples listed in Table 1 were synthesized using a solid-state route. In the first step, commercially available powders of metal oxide precursors (NbO, NbO, MoO, ZrO, TiO, WO, VO, ZrO, KO, CoO, FeO, GeO, GaO, AlO, ZnO, and / or MgO) were mixed in stoichiometric ratios and milled in a planetary ball mill using a 10:1 ball-to-powder ratio in a zirconia jar and grinding media at 550 rpm for 3 hours. The resulting powders were then heated in a stationary muffle furnace in air to form the desired crystalline phases. Samples 1–5, 12–16, 18, and 22 were heat-treated at 900 °C for 12 h; samples 6–9, 17, 19, and 20 were heat-treated at 1200 °C for 12 h; samples 6, 7, 17, 19, and 20 were further subjected to a 4-h heat-treatment step at 1350 °C; and samples 10, 11, and 21 were heat-treated at 1000 °C for 12 h. Samples 3 and 22 were further mixed with carbohydrate precursors (such as sucrose, maltodextrin, or other water-soluble carbohydrates) and dispersed in aqueous slurries at concentrations of 5, 10, 15, or 20 w / w% with an ionic surfactant. The mixtures were spray-dried in a laboratory-scale spray dryer (inlet temperature 220 °C, outlet temperature 95 °C, sample introduction rate 500 mL / h). The resulting powders were pyrolyzed in nitrogen at 600 °C for 5 h. Samples 5 and 18 were further annealed in nitrogen at 900 °C for 4 h.

[0115] Samples E1, E2, E6, E7, E8, E9, and E10 were prepared by ball milling as described above, impact milled at 20,000 rpm to achieve a particle size distribution of D90 < 20 μm, and then heat treated in air at 1200 °C for 12 hours in a muffle furnace or similar. Samples E8, E10, E11, E12, and E13 were further annealed in nitrogen at 1000 °C for 4 hours. E14 was annealed in nitrogen at 900 °C for 5 hours. Samples E3, E4, and E5 were heat treated at 1300 °C for 12 hours. Samples E1–E10 were deagglomerated after synthesis by impact milling or jet milling to achieve the desired particle size range.

[0116] Elemental analysis of samples Elemental analysis was performed by inductively coupled plasma-atomic emission spectroscopy (ICP-MS / OES). Measurements were performed on a Thermo Scientific ICP-OES Duo iCAP 7000 series instrument. Samples were digested using 5 ml of nitric acid and 1 ml of HF acid, and an internal standard was used to resolve instrument variations. This process uses plasma to vaporize materials into the atomic / ionic state of the elements. The atoms are in an excited state due to the high temperature and decay to the ground state through energy transitions. The characteristic radiation emitted by each excited ion is measured and analyzed. The results are shown in Table 2 below.

[0117] [Table 2] This table of elemental analyses shows that the predicted cation ratios were substantially achieved for each composition tested.

[0118] XRD characterization of samples The phase purity of some samples was analyzed using a Rigaku Miniflex powder X-ray diffractometer over the 2θ range (10–70°) at a scan rate of 1° / min.

[0119] Figure 1 shows the measured XRD diffraction patterns of Samples 1, 4, 14, 2, 5, 15, 16, 18, and 22 for Comparative Study A. All diffraction patterns have peaks at the same position (within an instrumental error of 0.1°), and are consistent with MoNb 12 O 33 The peaks are sharp and intense, with no amorphous background noise. This indicates that all samples are phase-pure and crystalline, with a crystallite size of approximately 200 nm according to the Scherrer equation and a crystal structure of MoNb 12 O 33 indicates a match.

[0120] Figure 2 shows the measured XRD diffraction patterns of samples 8 and 9. Figure E10 shows the XRD pattern of sample E11. All diffraction patterns have peaks at the same position (within an instrumental error of 0.1°), and are consistent with WNb12 O 33 The peaks are sharp and intense, with no amorphous background noise. This indicates that all samples are phase-pure and crystalline, with a crystallite size of approximately 200 nm according to the Scherrer equation and a crystal structure of WNb 12 O 33 indicates a match.

[0121] Figure 3 shows the measured XRD diffraction patterns of samples 6, 7, 17, 19, and 20 for Comparative Study B. All diffraction patterns have peaks at the same position (within an instrumental error of 0.1°), indicating that ZrNb 24 O 62 The peaks are sharp and intense, with no amorphous background noise. This indicates that all samples are phase-pure and crystalline, with a crystallite size of approximately 200 nm according to the Scherrer equation and a crystal structure of ZrNb. 24 O 62 indicates a match.

[0122] Figure 4 shows the measured XRD diffraction patterns of samples 10, 11, and 21. All diffraction patterns have peaks at the same positions (within an instrumental error of 0.1°), which correspond to VNbO. 25 The peaks are sharp and intense, with no amorphous background noise. This indicates that all samples are phase-pure and crystalline, with a crystallite size of approximately 200 nm according to the Scherrer formula and a crystal structure of VNbO. 25 indicates a match.

[0123] Figure 5 shows the measured XRD diffraction patterns of samples 12 and 13. Figure E10 shows the XRD pattern of sample E14. All diffraction patterns have peaks at the same position (within an instrumental error of 0.1°), indicating that WNbO 31The peaks are sharp and intense, with no amorphous background noise. This indicates that all samples are phase-pure and crystalline, with a crystallite size of approximately 200 nm according to the Scherrer formula and a crystal structure of WNbO. 31 indicates a match.

[0124] Figure E1 shows the measured XRD diffraction patterns of samples E1 and E2. Figure E10 shows the XRD pattern of sample E13. All diffraction patterns have peaks at the same position (within a range of 0.1-0.2°) and match the JCPDS Crystallography Database entry JCPDS22-353. There is no amorphous background noise, and the peaks are sharp and intense. This indicates that all samples are phase-pure and crystalline, with a crystallite size of 52±12 nm according to the Scherrer formula and a crystal structure of Zn2Nb 34 O 87 indicates a match.

[0125] Figure E2 shows the measured XRD diffraction patterns of samples E3, E4, and E5. Figure E10 shows the XRD pattern of sample E12. All diffraction patterns have peaks at the same positions (within a range of 0.1-0.2°) and correspond to JCPDS Crystallographic Database entry JCPDS72-159 (isostructural TiNb 10 O 29 ) There is no amorphous background noise and the peaks are sharp and intense. This indicates that all samples are phase-pure and crystalline, with a crystallite size of 53±16 nm according to the Scherrer equation and a crystal structure of AlNb 11 O 29 indicates a match.

[0126] Figure E3 shows the measured XRD diffraction patterns of samples E6, E7, and E8. All diffraction patterns have peaks at the same positions (within 0.1–0.2°) and correspond to ICSD Crystallographic Database entry 72683 (isostructural PNbO 25) There is no amorphous background noise and the peaks are sharp and intense. This indicates that all samples are phase-pure and crystalline, with a crystallite size of 53±3 nm according to the Scherrer equation and a crystal structure of GeNb 18 O 47 indicates a match.

[0127] Figure E4 shows the measured XRD diffraction patterns of samples E9 and E10. All diffraction patterns have peaks at the same positions (within a range of 0.1-0.2°) and match the JCPDS Crystallography Database entry JCPDS44-0467. There is no amorphous background noise, and the peaks are sharp and intense. This indicates that all samples are phase-pure and crystalline, with a crystallite size of 37±11 nm according to the Scherrer formula and a crystal structure of W5Nb 16 O 55 indicates a match.

[0128] TGA characterization of samples Thermogravimetric analysis (TGA) was performed on some samples using a Perkin Elmer Pyris1 system in a synthetic air atmosphere. The samples were first held at 30°C for 15 minutes, then heated from 30°C to 950°C at 5°C / min, and finally held at 950°C for 30 minutes. TGA was performed on sample 3 to quantify the carbon content and on sample 5 to characterize the mass gain associated with filling of oxygen vacancies.

[0129] Figure 6 shows the TGA characterization of Sample 3 in air. The rapid mass loss between approximately 400 and 500 °C is attributed to the decomposition of the carbon coating, a temperature corresponding to a mixture of amorphous and graphitic carbon. The amount of mass loss indicates that Sample 3 contains 1.1 wt. % carbon coating, which is consistent with the amount expected from the precursor stoichiometry.

[0130] Qualitative evaluation of oxygen vacancies As described above, Samples 5 and 18 were heat-treated at 900°C for 12 hours to form the active electrode material, and then further annealed in nitrogen (reducing atmosphere) at 900°C in a post-treatment heat treatment step. After the post-treatment heat treatment in nitrogen, a color change from white to deep purple was observed, indicating a change in the oxidation state and band structure of the material as a result of oxygen deficiency in the sample.

[0131] Samples E8, E10, E11, E12, and E13 were further annealed in nitrogen at 1000°C for 4 hours, and sample E14 was annealed in nitrogen at 900°C for 5 hours. Sample E7 changes from white to dark yellow when induced oxygen vacancies are introduced in sample E8. Sample E9 changes from off-white to blue-gray when induced oxygen vacancies are introduced in sample E10. Sample 8 changes from off-white to light blue in E11. Sample E3 changes from white to gray / black in E12. Sample E1 changes from white to gray / black in E3. Sample 12 changes from light yellow to dark blue in E14.

[0132] Particle size distribution analysis of samples Particle size distribution was obtained using a Horiba dry powder laser diffraction particle analyzer. The air pressure was maintained at 0.3 MPa. The results are shown in Table 3 below. [Table 3] Figure 7 shows the particle size distributions (measured particle size is secondary particle size, not crystal or crystallite size) of Samples 1, 2, 15, and 16 as representative of particle size distributions obtained by the solid-state route of this study without further processing or size optimization. The particle size distributions are generally bimodal, with the first mode being approximately 10 μm and the second mode being approximately 90 μm. Sample 3 shows a significant difference in particle size distribution, as shown in Figure 8, due to the post-processing steps of spray drying and pyrolysis.

[0133] All particle size distributions can also be refined by further processing steps, such as spray drying, ball milling, high-shear milling, jet milling, or impact milling, to reduce the particle size distribution to the desired range (e.g., d<20 μm, <10 μm, or <5 μm), as shown in Figure 17 and Table 3. Typically, the particle size distribution is tailored by optimizing the phase formation process (i.e., solid-state synthesis route) and post-processing steps for the target application. For example, for high-power Li-ion electrodes, a small average particle size is usually the goal, among other considerations.

[0134] Figure E5 shows the particle size distribution of the final form of samples E2, E4, E7, and E10, which were subsequently processed into electrode slurries and electrode inks.

[0135] SEM characterization of samples The morphology of some samples was analyzed by scanning electron microscopy (SEM).

[0136] Figures 9 and 10 show SEM images of Sample 3 before and after pyrolysis. The morphology of carbon-coated porous microspheres is observed, with primary crystallites organized into secondary particles. This material appears to have homogeneous porous particles that can be efficiently packed to form high-density electrodes. The elimination of the need for a conductive coating for SEM imaging significantly improves the qualitative conductivity, implying an order of magnitude improvement in the conductivity of the material's surface. Figure 18 shows a surface SEM image of particles within the electrode of Sample 22. The conductive carbon black particles contained in the electrode can also be seen on the right side of the image. This provides visual evidence of a conformal carbon coating around the MNO material.

[0137] FIG. 11 shows SEM images of Samples 1 and 2, which confirm the XRD and PSD data by showing micron-sized particles of compact secondary particles composed of primary crystallites of approximately 200 nm.

[0138] Electrochemical testing of samples For initial analysis, electrochemical testing was performed in half-coin cells (CR2032 size). In half-coin testing, materials are tested at the electrode against a Li metal electrode to evaluate the fundamental performance of the material. In the following example, the active material composition to be tested was combined with N-methylpyrrolidone (NMP), carbon black, which acts as a conductive additive, and poly(vinyl difluoride) (PVDF) binder, and mixed in a laboratory-scale centrifugal planetary mixer to form a slurry (although it is also possible to form an aqueous slurry using water instead of NMP). The non-NMP composition of the slurry was 80 wt% active material, 10 wt% conductive additive, and 10 wt% binder. This slurry was then doctor blade coated onto an Al foil current collector at the desired coverage of 1 mg / cm. 2 The electrodes were then die-cut to the desired size and combined with a separator (Celgard porous PP / PE), Li metal, and electrolyte (1 M LiPF6 in EC / DEC) in a steel coin cell case, which was then sealed under pressure. Formation cycling was then performed, consisting of two full charge and discharge cycles at a low current rate (C / 20). After formation, further cycling at fixed or variable current densities may be performed as needed. These tests are referred to as "half-cell galvanostatic cycling" for future reference. For samples E1-E10, the electrolyte was changed to 1.3 M LiPF6 in 3:7 EC / DEC, and formation cycling was performed with two charge and discharge cycles in the limited range of 1.1 to 3.0 V at C / 10. The values ​​shown for these samples are the average of three measurements, and the error is the standard deviation.

[0139] A homogeneous, smooth coating on a current collector foil, free of visible defects, was also prepared using a centrifugal planetary mixer with a composition of 94 wt% active material, 4 wt% conductive additive, and 2 wt% binder, as described above. This coating achieved a 700 mAh / cm2 output at a voltage range of 0.7 to 3.0 V at C / 20. 3 Over 640mAh / cm2 of available volumetric capacity in the voltage range of 1.1 to 3.0V at C / 5 3To demonstrate the potential volumetric capacity exceeding 3.0 g / cm at 80 °C, 3 Up to 1.3~1.7mAh / cm 2 This is an important demonstration of the viability of these materials for commercially attractive electrode power cell formulations, where high volumetric capacities are possible by maintaining performance after calendering to high electrode densities: 1.0, 1.5, 2.0, 2.5, or 3.0 mAh / cm. 2 Lower loadings, including 3.0, 4.0, or 5.0 mAh / cm, may be useful for Li-ion cells with a focus on power performance. 2 Higher loadings may be useful for Li-ion cells with a focus on energy performance. Calendering of these materials has demonstrated electrode porosity down to 35%, with porosity typically in the range of 35-40%. Electrode porosity is defined as the measured electrode density divided by the average true density adjusted for the weight percent concentration of each electrode component.

[0140] The electrical conductivity of the fabricated electrodes, including the samples listed in Table 1, was measured using a four-point probe thin film resistance measurement device. Slurries were prepared according to the procedure described above, and 1 mg / cm 2 The coating was applied to a dielectric Mylar film at a coating weight of 1000 ppm. Then, electrode-sized disks were punched out and the resistance of the coating was measured using a four-point probe. The bulk resistivity can be calculated from the measured resistance using the following formula:

[0141] (3) Bulk resistivity (ρ)=2πs(V / I);R=V / I;s=0.1cm =2πx0.1xR(Ω) The results of this study are shown in Table 4 below. [Table 4] Four-point probe resistance measurements were also performed to quantify the electrical resistivity of samples E1-E14. 2Coatings were performed on Mylar films at a coating weight of 1000 ppm using a different Ossila instrument (T2001A3-UK) at 23°C. The sheet resistance (Ω / square) results are summarized in Table 4a. Errors are based on the standard deviation of triplicate measurements. [Table 5] Direct current internal resistance (DCIR) and the resulting area-specific impedance (ASI) are key measurements of the electrode's internal resistance in Li-ion cells. A typical measurement involves cycling a previously formed cell at C / 2 for three cycles. The electrode is delithiated, and a C / 2 discharge current is applied for one hour to achieve approximately 50% lithiation. After allowing the cell to rest for 30 minutes to equilibrate at OCV (open circuit voltage), a 5C current pulse is applied for 10 seconds, followed by another 30-minute rest period to reach OCV. During the 10-second pulse, the voltage response is sampled at a higher frequency to accurately determine the average internal resistance. The difference between the OCVs (the linear average between the initial OCV before the pulse and the OCV afterward) and the measured voltage is then used to calculate the resistance, V = IR. The resistance is then multiplied by the electrode's area to obtain the ASI.

[0142] The results of this study are shown in Table 5 below. [Table 6] In addition, for some samples, the reversible specific capacity C / 20, initial coulombic efficiency, C / 20, 5C / 0.5C capacity retention rate, and Li / Li at 10C / 0.5C capacity retention rate were measured. +The nominal lithiation voltages for Li / Li+ were tested. The results are shown in Table 6 below. The nominal lithiation voltage for Li / Li+ was calculated by dividing the integral of the V / Q curve by the total capacity at C / 20 lithiation on the second cycle. The capacity retention at 10C and 5C was calculated by taking the specific capacity at 10C or 5C and dividing it by the specific capacity at 0.5C. Note that the capacity retention was tested in a symmetric cycling test, where the C-rates during lithiation and delithiation are equal. When tested with an asymmetric cycling program, a 10C / 0.5C capacity retention of greater than 89% was consistently observed.

[0143] Samples E1-E10 were tested with slight differences as shown in Table 6a. The reversible specific capacity shown is the second cycle delithiation capacity at C / 10 and Li / Li + The nominal lithiation voltage for was at the second cycle at C / 10, and rate tests were performed in an asymmetric cycling program without a constant voltage step (i.e., constant current), with lithiation at C / 5 and delithiation at increasing C rates.

[0144] [Table 7]

[0145] [Table 8] Modifications of the Wadsley-Roth and bronze structures of mixed niobium oxide systems outlined in the claims demonstrate the applicability of the invention to improve active material performance in Li-ion cells. As explained, the substitution of non-Nb cations to form mixed cation structures increases entropy (see disorder) in the crystal structure, which can reduce the potential energy barrier for Li-ion diffusion through the introduction of small defects (e.g., Samples E7, 16, etc.). Modifications by creating mixed cation structures while maintaining the overall oxidation state demonstrate the potential for improvement through altering the ionic radius, e.g., the Mo in Sample 14. 6+ Cation W 6+ or Al in samples E4 and E5 3+ Fe instead of 3+ Or Ga 3+ Small modifications of the crystal parameters and Li-ion cavities (e.g., tuning the reversibility of the Type VI cavity in the Wadsley-Roth structure) can result in improvements in specific capacitance, an increase in the Coulombic efficiency of cycling due to a reduction in Li-ion diffusion and Li-ion trapping, such as the substitution of Zn in sample E2. Modifications by creating mixed cation structures leading to an increase in oxidation states (e.g., the substitution of Zn in sample E3) can result in improvements in specific capacitance, an increase in the Coulombic efficiency of cycling due to a reduction in Li-ion diffusion and Li-ion trapping. 2+ Ge to replace 4+ , or Zr in sample 19 4+ Mo to replace 6+ ) show similar potential benefits of altering the ionic radius related to capacity and efficiency, combined with introducing additional electron holes into the structure to aid conductivity. Modification by creating mixed cation structures resulting in a reduction in oxidation states (e.g., Ge in sample E7). 4+ K to replace + and Co 3+ , or Mo in sample 2 6+ Ti to replace 4+) show similar potential benefits related to capacity and efficiency, combined with the introduction of oxygen vacancies and additional electrons into the structure to aid conductivity, as well as modifications to the ionic radius. Modification by inducing oxygen vacancies from high-temperature treatment under inert or reducing conditions provides reduced structures with only a small percentage of oxygen loss from the structure, significantly improved conductivity (e.g., Samples 5, E10, and E12-14), and improved electrochemical properties, such as capacity retention at high C-rates (e.g., Sample 5, E13). The combination of mixed cation structures with induced oxygen vacancies allows for the combination of multiple beneficial effects (e.g., increased specific capacitance, reduced electrical resistance) (e.g., Sample 18, E8).

[0146] 12, 13, and 19 show the unmodified and modified MoNb 12 O 33 (Fig. 12 - Samples 1 and 6), ZrNb 24 O 62 (Fig. 13 - Samples 6 and 7), and W7Nb4O 31Representative lithiation / delithiation curves for the first two formation cycles at a C / 20 rate are shown in Figure 19 (Samples 12 and 13). Figure 12 shows that approximately 90% of the specific capacity of the demonstrated Sample 16 falls within a narrow voltage range of approximately 1.2 to 2.0 V, and Figure 13 shows that approximately 90% of the capacity of the demonstrated Sample 7 falls within a narrow range of approximately 1.25 to 1.75 V. These data highlight the attractive voltage profile achievable with MNO crystals based on the Wadsley-Roth crystal structure. Figure 19 shows that approximately 90% of the specific capacity of Sample 13 falls within a narrow range of approximately 1.2 to 2.2 V. This demonstrates that an attractive voltage profile can be achieved with MNO crystals based on the tetragonal bronze crystal structure. Next, composite metal oxide Samples 7, 16, and 13 demonstrate improved specific capacity compared to their unmodified crystal counterparts, Samples 1, 6, and 12. This is because the cations contained in the composite structure have different ionic radii and oxidation states, which increase the number of sites within the crystal that can accommodate Li ions, thereby increasing the capacity. We observed an increase in ICE between Samples 1 and 16, and between Samples 12 and 13. This further demonstrates that when Li ion sites are modified to allow desorption, Li ions inserted into the modified crystal structure can delithiate more efficiently.

[0147] Figure E5 shows the particle size distribution of samples E2, E4, E8 and E11. The distribution mainly contains a single peak with a narrow distribution, i.e., D 10 and D 90 is D 50 This is advantageous for processing the material in the electrode slurry to efficiently pack the material and maintain uniform electrochemical performance (e.g., smaller particles become fully lithiated before larger particles due to shorter diffusion distances).

[0148] Figure E6 shows the modification of sample E1, especially Zn 2+ The cations are converted to higher valence Ge. 4+The observed improvement in specific capacity due to the substitution of Ge with K and Co cations is shown in Figure E7. Figure E9 shows the improvement in ICE and reduction in nominal lithiation voltage possible due to the introduction of induced oxygen vacancies, which reduce polarization effects through improved conductivity and improved reversibility of the lithiation / delithiation process.

[0149] Across all materials tested, each material in accordance with the present invention demonstrates an improvement over the unmodified "parent" crystal structure. This is inferred from resistivity / impedance measurements using two different methods and from electrochemical testing performed in Li-ion half-coin cells, particularly the capacity retention at increased current densities (see Table 6, Figures 14 and 15). Without wishing to be bound by theory, the inventors suggest that this is the result of increased ionic and electronic conductivity of the material due to modifications to the crystal lattice, either through the introduction of defects or by changing the ionic radius. DCIR / ASI (Table 5) and EIS (Figure 16) measurements also indicate a decrease in resistance or impedance upon material modification. Li-ion diffusion rates may also increase in materials in accordance with the present invention compared to the unmodified "parent" material. As shown in Table 6, the specific capacitance itself may potentially increase because doping / exchanging metal ions of different sizes expands or contracts the crystal lattice, allowing for more Li-ion insertion or reversible insertion than is possible in the unmodified structure.

[0150] The data in Table 4 show a significant decrease in resistivity between Sample 1 (comparative) and Samples 2, 4, 5, 14, 15, 16, 18, and 22, demonstrating the effectiveness of embodiments of the present invention in improving the conductivity of the crystal structure through both cation exchange, oxygen vacancies, and carbon coating. Samples 17, 19, and 20 also show similarly low resistivity relative to Sample 6. Although resistivity increased slightly when 0.05 equivalents of V species were incorporated into the host crystal of Sample 7, an improvement in specific capacitance was observed, likely due to a change in available Li-ion sites in the crystal lattice as a result of the different ionic radii of V relative to Zr (see Table 6).

[0151] The data in Table 5 reflect the trend shown in Table 4, showing a large decrease in DCIR / ASI from Sample 1 (comparison) to Samples 2, 4, 14, 16, 18, and 22. Samples 7, 17, and 19 show higher DCIRs than these due to DCIR, which is related to different host crystal structures. While not wishing to be bound by theory, the inventors believe that Samples 7, 17, and 19 exhibit a higher DCIR / ASI than the comparative material (ZrNb) in Sample 6 due to changes in the crystal lattice caused by the introduction of cations with different ionic radii. 24 O 62 ), but as shown in Table 4, these structures for Samples 17 and 19 are still beneficial from a conductivity standpoint, as they reduce electrical resistivity, thereby minimizing Joule heating and allowing for more uniform current distribution throughout the material, which in turn improves the safety and lifetime of Li-ion systems. For Sample 7, no improvement is demonstrated by utilizing V to replace Zr, although an increase in specific capacitance is observed as noted above.

[0152] In Table 6, across most samples, there is a trend for improvements in specific capacity, initial coulombic efficiency (ICE), nominal lithiation voltage for Li / Li+, and importantly, capacity retention at 5C and 10C relative to 0.5C for materials according to the invention relative to comparative "parent" materials (e.g., Samples 1, 6, 8, 10, 12). For example, Samples 2, 3, 4, 5, 14, 15, 16, 18, and 22 all show improvements in one or more of these parameters relative to Sample 1. Across multiple parameters, improvements are seen for Samples 7, 17, and 19 relative to Sample 6, with improvements in specific capacity or capacity retention; Samples 11 and 21 relative to Sample 10, with improvements in ICE and capacity retention; and Sample 9 relative to Sample 8, with improvements seen in all parameters for Sample 13 relative to Sample 12*.

[0153] 14 and 15 show improved capacity retention at higher cycling rates for the materials according to the invention (Samples 4, 16, 7, 17) versus the comparative materials (Samples 1 and 6).

[0154] Electrochemical impedance spectroscopy (EIS) measurements were also performed to further understand the impedance present in the electrodes of Li-ion cells. In a typical measurement, cells are prepared to approximately 50% lithiation, as in DCIR measurements, and then the impedance is measured while varying the frequency of alternating charge / discharge current pulses. A Nyquist plot is generated by plotting the real and imaginary components as axes and varying the AC frequency. From this Li-ion cell plot, various types of impedance within the cell can be identified, but interpretation is generally complex. For example, ohmic resistance can be partially separated from electrochemical double-layer effects, which can also be separated from diffusion effects.

[0155] Figures 16(a) and 16(b) show the EIS spectra of Sample 1 (comparison) and Samples 16 and 7 (samples according to the invention).

[0156] *** The features disclosed in the foregoing description, or the following claims, or the accompanying drawings, may be expressed in their specific form, or in terms of means for performing a disclosed function, or methods or processes for obtaining a disclosed result, as appropriate, and may be utilized separately or in any combination of those features to realize the invention in various of its forms.

[0157] While the present invention has been described in conjunction with the exemplary embodiments set forth above, many equivalent modifications and variations will become apparent to those skilled in the art given this disclosure. Accordingly, the exemplary embodiments of the invention set forth above are considered to be illustrative and not limiting. Various changes can be made to the described embodiments without departing from the spirit and scope of the invention.

[0158] For the avoidance of doubt, the theoretical explanations provided herein are provided for the purpose of enhancing the understanding of the reader, and the inventors do not wish to be bound by any of these theoretical explanations.

[0159] The section headings used herein are for organizational purposes only and shall not be construed as limiting the subject matter described.

[0160] Throughout this specification, including the claims which follow, unless the context otherwise requires, the words "comprise" and "include", and variations such as "comprise", "comprising" and "including", will be understood to mean the inclusion of a stated integer or step or group of integers or steps and not to the exclusion of other integers or steps or groups of integers or steps.

[0161] As used in this specification and the appended claims, it should be noted that the singular forms "a", "an", and "the" include plural referents unless the context clearly dictates otherwise. A range may be expressed as "about" a particular value and / or "about" another particular value. When expressing such a range, as another embodiment, it includes from a particular value and / or to another particular value. Similarly, when a value is expressed as an approximation, it is understood that the use of the preceding "about" forms another embodiment of the particular value. "About" with respect to a numerical value is optional and means, for example, ±10%.

[0162] Numbered embodiments The following numbered embodiments form part of this description.

[0163] 1. General formula [M1] x [M2] (1-x) [Nb] y [O] z The active electrode material represented by, M1 and M2 are different,[[]] M1 represents one or more of Ti, Mg, V, Cr, W, Zr, Nb, Mo, Cu, Fe, Ga, Ge, Ca, K, Ni, Co, Al, Sn, Mn, Ce, Te, Se, Si, Sb, Y, La, Hf, Ta, Re, Zn, In, or Cd,[[]] M2 represents one or more of Mg, V, Cr, W, Zr, Nb, Mo, Cu, Fe, Ga, Ge, Ca, K, Ni, Co, Al, Sn, Mn, Ce, Te, Se, Si, Sb, Y, La, Hf, Ta, Re, Zn, In, or Cd,[[]] x satisfies 0 < x < 0.5,[[]] y satisfies 0.5 ≤ y ≤ 49,[[]] z satisfies 4 ≤ z ≤ 124, the active electrode material.

[0164] 2. The active electrode material according to embodiment 1, wherein M2 is selected from one or more of Mo, W, V, or Zr.

[0165] 3. The said [M1] x[M2] (1-x) [Nb] y [O] z is M1 x Mo (1-x) Nb 12 O (33-33α) M1 x W (1-x) Nb 12 O (33-33α) M1 x V (1-x) Nb9O (25-25α) M1 x Zr (1-x) ​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​ZrNb 24 O (62-62α) W7Nb4O (31-31α) W9Nb8O (47-47α) is selected from the group consisting of The active electrode material, wherein α satisfies 0<α≦0.05.

[0168] 6. The active electrode material of any one of the preceding embodiments, wherein at least a portion of the material has a Wadsley-Roth crystal structure and / or a tetragonal tungsten bronze crystal structure.

[0169] 7. The active electrode material of any one of the preceding embodiments, wherein the active electrode material comprises a plurality of primary crystallites, some or all of the primary crystallites optionally agglomerated into secondary particles.

[0170] 8. The active electrode material of embodiment 7, wherein the average diameter of the primary crystallites is from 10 nm to 10 μm.

[0171] 9. The active electrode material of embodiment 7 or embodiment 8, wherein some or all of the primary crystallites aggregate into secondary particles, the secondary particles having an average diameter of 1 μm to 30 μm.

[0172] 10. The active electrode material of any one of the preceding embodiments, wherein the active electrode material includes a carbon coating formed on the surfaces of the primary crystallites and / or the secondary particles.

[0173] 11. The active electrode material of embodiment 10, wherein the carbon coating is present in an amount of up to 5 w / w%, based on the total weight of the active electrode material.

[0174] 12. The crystalline structure of the active electrode material as determined by X-ray diffraction analysis is MoNb 12 O 33 WNb 12 O 33 ZrNb 24 O 62 VNbO 25 W7Nb4O 31 W9Nb8O 47 10. The active electrode material of any one of the preceding embodiments, wherein the active electrode material corresponds to one or more crystalline structures of

[0175] 13. The active electrode material of any one of the preceding embodiments, further comprising Li and / or Na.

[0176] 14. An electrochemical device comprising an anode, a cathode, and an electrolyte disposed between the anode and the cathode, wherein the anode comprises the electrode active material of any one of embodiments 1 to 13.

[0177] 15. Methods of using the electrode active material of any one of embodiments 1-13 (i) as an anode active material, or a component of an anode active material, in an anode, in combination with a cathode and electrolyte of a lithium-ion battery for charging and discharging the battery, or (ii) as an anode active material, or a component of an anode active material, in combination with a cathode and electrolyte of a sodium-ion battery for charging and discharging the battery.

[0178] 16. A method for processing the electrode active material of any one of embodiments 1-13 (i) as or into an anode active material for a lithium ion battery, the method comprising diffusing lithium ions into the anode active material; or a method for processing the electrode active material of any one of claims 1-23 (ii) as or into an anode active material for a sodium ion battery, the method comprising diffusing sodium ions into the anode active material.

[0179] 17. A method for producing an active electrode material according to any one of embodiments 1 to 13, the method comprising: Providing one or more precursor materials; mixing the precursor materials to form a precursor material mixture; heat treating the precursor material mixture at a temperature ranging from 400°C to 1350°C to form the active electrode material; The method includes the steps of:

[0180] 18. The method of producing an active electrode material of embodiment 17, wherein the one or more precursor materials include a source of Mo, a source of W, a source of Zr, or a source of V, and a source of Nb.

[0181] 19. The method for producing an active electrode material of embodiment 17 or embodiment 18, wherein the one or more precursor materials include a source of M1 ions, a source of M2 ions, and a source of Nb, and the resulting active electrode material is as defined in any one of embodiments 1 to 4 or embodiments 6 to 13 dependent from embodiment 1.

[0182] 20. The method of making an active electrode material of embodiment 17, wherein the precursor material comprises one or more metal oxides, metal hydroxides, metal salts, or oxalates.

[0183] 21. The method of any one of embodiments 17-20, wherein the one or more precursor materials are particulate materials, optionally having an average particle size less than 20 μm in diameter.

[0184] 22. The method of any one of embodiments 17-21, wherein the step of mixing the precursor materials to form a precursor material mixture is performed by a process selected from dry or wet planetary ball milling, rolling ball milling, high shear milling, air jet milling, and / or impact milling.

[0185] 23. The method of any one of embodiments 17-22, wherein the step of heat treating the precursor material mixture is carried out for a time period of 1 hour to 14 hours.

[0186] 24. The method of any one of embodiments 17 to 23, wherein the step of heat treating the precursor material mixture is carried out in a gas atmosphere, the gas being selected from air, N2, Ar, He, CO2, CO, O2, H2, and mixtures thereof.

[0187] 25. The method comprises: (i) heat treating the active electrode material; (ii) mixing the active electrode material with a carbon source, and optionally further heating the mixture, thereby forming a carbon coating on the active electrode material; (iii) spray drying the active electrode material; and / or (iv) milling the active electrode material to modify the particle size of the active electrode material; 25. The method according to any one of embodiments 17 to 24, comprising one or more post-processing steps selected from:

[0188] References Several publications are cited above in order to more fully describe and disclose the present invention and the state of the art to which it pertains. Full citations for these references are set forth below. Each of these references is incorporated herein in its entirety.

[0189] Goodenough and Park, “The Li-Ion Rechargeable Battery: A Perspective”, Journal of the American Chemical Society 2013 135 (4), 1167-1176, DOI: 10.1021 / ja3091438 Griffith et al., “High-Rate Intercalation without Nanostructuring in Metastable Nb2O5Bronze Phases, Journal of the American Chemical Society 2016 138 (28), 8888-8899, DOI: 10.1021 / jacs.6b04345 Griffith et al., “Structural Stability from Crystallographic Shear in TiO2Nb2O5Phases: Cation Ordering and Lithiation Behavior of TiNb 24 O 62 ” Inorganic Chemistry (2017), 56, 7, 4002-4010 Montemayor et al., “Lithium insertion in two tetragonal tungsten bronze type phases, M8W9O47 (M = Nb and Ta)”, Journal of Material Chemistry (1998), 8, 2777-2781 Zhou et al., “Facile Spray Drying Route for the Three-Dimensional Graphene Encapsulated Fe2O3Nanoparticles for Lithium Ion Battery Anodes”, Ind.Eng.Chem.Res. (2013), 52, 1197-1204 Zhu et al., “MoNb 12 O 33 as a new anode material for high- capacity, safe, rapid and durable Li+ storage: structural characteristics, electrochemical properties and working mechanisms”, J.Mater.Chem.A. (2019),7, 6522-6532 Yang et al., “Porous ZrNb 24 O 62Nanowires with Pseudocapacitive Behavior Achieve High-Performance Lithium-Ion Storage”.J.Mater.Chem.A. (2017) 5. 10.1039 / C7TA07347J. The specific embodiments of the present invention are as follows. [Embodiment 1] A working electrode material represented by the general formula [M1] x [M2] (1-x) [Nb] y [O] z where M1 and M2 are different, M1 represents one or more of Ti, Mg, V, Cr, W, Zr, Mo, Cu, Fe, Ga, Ge, Ca, K, Ni, Co, Al, Sn, Mn, Ce, Te, Se, Si, Sb, Y, La, Hf, Ta, Re, Zn, In, or Cd, M2 represents one or more of Mg, V, Cr, W, Zr, Mo, Cu, Ga, Ge, Ca, K, Ni, Co, Al, Sn, Mn, Ce, Sb, Y, La, Hf, Ta, Zn, In, or Cd, x satisfies 0 < x < 0.5, y satisfies 0.5 ≤ y ≤ 49, z satisfies 4 ≤ z ≤ 124, the working electrode material. [Embodiment 2] (i) M2 is selected from one or more of Mo, W, V, Zr, Al, Zn, Ga, Ge, Ta, Cr, Cu, K, Mg, Ni, or Hf, or (ii) M2 is selected from one or more of Mo, W, V, Zr, Al, Zn, Ga, or Ge, or (iii) M2 is selected from one or more of Mo, W, V, or Zr, the working electrode material according to Embodiment 1. [Embodiment 3] The [M1] x [M2] (1-x) [Nb] y [O] z is (i) M1 x Mo (1-x) Nb 12 O (33-33α) M1 x W (1-x) Nb 12 O (33-33α) M1 xV (1-x) [[ID= 9 O (25-25α) M1 x Zr (1-x) ​ 24 O (62-62α) M1 x W (1-x) ​ 0.57 O (4.43-4.43α) M1 x W (1-x) ​ 0.89 O (5.22-5.22α) M1 x ​ (1-x) ​ 17 O (43.5-43.5α) M1 x ​ (1-x) ​ 17 O (43.5-43.5α) M1 x Al (1-x) ​ 11 O (29-29α) M1 x ​ (1-x) ​ 11 O (29-29α) M1 x ​ (1-x) ​ 18 O (47-47α) M1 x W (1-x) ​ 1.125 O (5.81-5.81α) M1 x W (1-x) ​ 3.2 O (11-11α) M1 x Al (1-x) ​ 49 O (124-124α) M1 x ​ (1-x) ​ 49 O (124-124α) ​ ​ x ​ (1-x) ​ 12 O (33-33α) M1 x W (1-x) ​ 12 O (33-33α) M1 x V (1-x) ​ 9 O (25-25α) M1 x Zr (1-x) ​ 24 O (62-62α) M1 x W (1-x)​ 0.57 O (4.43-4.43α) M1 x W (1-x) ​ 0.89 O (5.22-5.22α) M1 x ​ (1-x) ​ 17 O (43.5-43.5α) M1 x Al (1-x) ​ 11 O (29-29α) M1 x ​ (1-x) ​ 18 O (47-47α) ​ ​ x ​ (1-x) ​ 12 O (33-33α) M1 x W (1-x) ​ 12 O (33-33α) M1 x V (1-x) ​ 9 O (25-25α) M1 x Zr (1-x) ​ 24 O (62-62α) M1 x W (1-x) ​ 0.57 O (4.43-4.43α) M1 x W (1-x) ​ 0.89 O (5.22-5.22α) ​ ​ ​ ​ ​ ​ x ​ (1-x) ​ 12 O (33-33α) ​ ​ ​ x W (1-x) ​ 0.57 O (4.43-4.43α) wherein α satisfies 0≦α≦0.05. [Aspect 6] The active electrode material has the formula M1 x Zn (1-x) Nb 17 O (43.5-43.5α) wherein α satisfies 0≦α≦0.05. [Aspect 7] The active electrode material has the formula M1 x Al (1-x) Nb 11 O (29-29α) wherein α satisfies 0≦α≦0.05. [Aspect 8] (i) M1 represents one or more of K, Mg, Ca, Y, Ti, Zr, Hf, V, Ta, Cr, Mo, W, Mn, Fe, Co, Ni, Cu, Zn, Al, Ga, Si, Ge, Sn, Sb, or (ii) M1 represents one or more of Ti, Mg, V, Cr, W, Zr, Mo, Cu, Ga, Ge, K, Ni, Al, Hf, Ta, or Zn; or (iii) The active electrode material of any preceding embodiment, wherein M1 represents one or more of Ti, Mg, V, Cr, W, Zr, Mo, Ga, Ge, Al, or Zn. [Aspect 9]

[0023] The active electrode material of any preceding embodiment, wherein M1 has an oxidation state equal to or lower than M2, and optionally M1 has an oxidation state lower than M2. [Aspect 10]

[0023] The active electrode material of any preceding embodiment, wherein M1 comprises at least one cation having an oxidation state of 4+ and M2 comprises at least one cation having an oxidation state of 6+, optionally wherein M1 has a 4+ oxidation state and M2 has a 6+ oxidation state. [Aspect 11] The crystalline structure of the active electrode material, as determined by X-ray diffraction, corresponds to the crystalline structure of the active electrode material in an unmodified form, the unmodified form having the formula [M2][Nb] y [O] z wherein M2 consists of a single element, and the unmodified form is not oxygen deficient, and the unmodified form is I Nb 5 O 13 、M2 I 6 Nb 10.8 O 30 、M2 II Nb 2 O 6 、M2 II 2 Nb 34 O 87 、M2 III Nb 11 O 29 、M2 III Nb 49 O 124 、M2 IV Nb 24 O 62 、M2 IV Nb 2 O 7 、M2 IV 2 Nb 10 O 29 、M2 IV 2 Nb 14 O 39 、M2 IV Nb14 O 37 、M2 IV Nb 6 O 17 、M2 IV Nb 18 O 47 、M2 V Nb 9 O 25 、M2 V 4 Nb 18 O 55 、M2 V 3 Nb 17 O 50 、M2 VI Nb 12 O 33 、M2 VI 4 Nb 26 O 77 、M2 VI 3 Nb 14 O 44 、M2 VI 5 Nb 16 O 55 、M2 VI 8 Nb 18 O 69 、M2 VI Nb 2 O 8 、M2 VI 16 Nb 18 O 93 、M2 VI 20 Nb22 O 115 、M2 VI 9 Nb 8 O 47 、M2 VI 82 Nb 54 O 381 、M2 VI 31 Nb 20 O 143 、M2 VI 7 Nb 4 O 31 、M2 VI 15 Nb 2 O 50 、M2 VI 3 Nb 2 O 14 , and M2 VI 11 Nb 12 O 63 wherein the numbers I, II, III, IV, V, and VI represent the oxidation states of M2. [Aspect 12] (i) x satisfies 0.01≦x≦0.4, and / or (ii) x satisfies 0.05≦x≦0.25, and / or (iii) The active electrode material of any preceding embodiment, wherein x is about 0.05. [Aspect 13]

[0023] The active electrode material of any one of the preceding embodiments, wherein the active electrode material is oxygen deficient, and optionally z is defined as z=(z'-z'α), and α satisfies 0<α≦0.05. [Aspect 14] 10. The active electrode material of any one of the preceding aspects, wherein at least a portion of the material has a Wadsley-Roth crystal structure and / or a tetragonal tungsten bronze crystal structure, or wherein substantially all of the active electrode material has a Wadsley-Roth crystal structure and / or a tetragonal tungsten bronze crystal structure. [Aspect 15] 2. The active electrode material of any one of the preceding aspects, wherein the active electrode material comprises a plurality of primary crystallites, some or all of the primary crystallites optionally aggregated into secondary particles. [Aspect 16] 16. The active electrode material of aspect 15, wherein the average diameter of the primary crystallites is 10 nm to 10 μm. [Aspect 17] 17. The active electrode material of claim 15 or 16, wherein some or all of the primary crystallites aggregate into secondary particles, the secondary particles having an average diameter of 1 μm to 30 μm or 2 μm to 15 μm. [Aspect 18] The active electrode material is 0.1 to 100 m 2 / g, or 0.5 to 50 m 2 / g, or 1 to 20 m 2

[0029] The active electrode material of any preceding embodiment, having a BET surface area in the range of 1 / g. [Aspect 19] 10. The active electrode material of any one of the preceding aspects, wherein the active electrode material includes a carbon coating formed on the surfaces of the primary crystallites and / or the secondary particles. [Aspect 20] 20. The active electrode material of embodiment 19, wherein the carbon coating is present in an amount of up to 5 w / w%, based on the total weight of the active electrode material. [Aspect 21] The crystalline structure of the active electrode material as determined by X-ray diffraction analysis is (i) MoNb 12 O 33 WNb 12 O 33 VNb 9 O 25 ZrNb 24 O 62 W 7 Nb 4 O 31 W 9 Nb 8 O 47 Zn 2 Nb 34 O 87 Cu 2 Nb 34 O 87 AlNb 11 O 29 GaN 11 O 29 GeNb 18 O 47 W 16 Nb 18 O 93 W 5 Nb 16 O 55 AlNb 49 O 124 GaN 49 O 124 ,or (ii) MoNb 12 O 33 WNb 12 O 33 VNb 9 O 25 ZrNb 24 O 62 W 4 Nb 7 O 31 W 9 Nb 8 O 47 Zn 2 Nb 34 O 87 AlNb 11 O 29 GeNb 18 O 47 ,or (iii) MoNb 12 O 33 WNb 12 O 33 ZrNb 24 O 62 VNb 9 O 25 W 7 Nb 4 O 31 W 9 Nb 8 O 47

[0037] The active electrode material of any one of the preceding embodiments, wherein the active electrode material corresponds to one or more crystalline structures of [Aspect 22] The crystalline structure of the active electrode material is TiNb 2 O 7

[0033] The active electrode material of any one of the preceding embodiments, wherein the active electrode material does not correspond to a crystal structure of [Aspect 23]

[0037] The active electrode material of any one of the preceding embodiments, further comprising Li and / or Na. [Aspect 24] 24. An electrochemical device comprising: an anode, a cathode, and an electrolyte disposed between the anode and the cathode, wherein the anode comprises the electrode active material according to any one of aspects 1 to 23. [Aspect 25] A method of using the electrode active material of any one of Aspects 1 to 23: (i) as an anode active material, or a component of an anode active material, in an anode in combination with a cathode and electrolyte of a lithium-ion battery for charging and discharging the lithium-ion battery; or (ii) as an anode active material, or a component of an anode active material, in combination with a cathode and electrolyte of a sodium-ion battery for charging and discharging the sodium-ion battery. [Aspect 26] A method of processing the electrode active material of any one of Aspects 1 to 23 (i) as or into an anode active material for a lithium ion battery, the method comprising diffusing lithium ions into the anode active material; or a method of processing the electrode active material of any one of Aspects 1 to 23 (ii) as or into an anode active material for a sodium ion battery, the method comprising diffusing sodium ions into the anode active material. [Aspect 27] A method for producing an active electrode material according to any one of aspects 1 to 23, the method comprising: Providing one or more precursor materials; mixing the precursor materials to form a precursor material mixture; heat treating the precursor material mixture at a temperature ranging from 400°C to 1350°C to form the active electrode material; The method includes the steps of: [Aspect 28] 28. The method of claim 27, wherein the one or more precursor materials comprise a source of M1 ions, a source of M2 ions, and a source of Nb. [Aspect 29]

[0019] The method of claim 27 or 28, wherein the precursor material comprises one or more metal oxides, metal hydroxides, metal salts, or oxalates. [Aspect 30] Aspect 30. The method of any one of aspects 27-29, wherein the one or more precursor materials are particulate materials, optionally having an average particle size less than 20 μm in diameter. [Aspect 31]

[0039] Aspect 31. The method of any one of aspects 27-30, wherein mixing the precursor materials to form a precursor material mixture is performed by a process selected from dry or wet planetary ball milling, rolling ball milling, high shear milling, air jet milling, and / or impact milling. [Aspect 32] Aspect 32. The method of any one of aspects 27-31, wherein the step of heat-treating the precursor material mixture is carried out for a time period of 1 hour to 14 hours. [Aspect 33] The step of heat treating the precursor material mixture is carried out in a gas atmosphere, the gas being air, N 2 , Ar, He, CO 2 , CO, O 2 、H 2 33. The method according to any one of aspects 27 to 32, wherein the hydroxybenzoate is selected from the group consisting of hydroxybenzoates, ... [Aspect 34] The method comprises: (i) heat treating the active electrode material, optionally wherein the heat treating step is carried out in an inert gas atmosphere or a reducing gas atmosphere; (ii) mixing the active electrode material with a carbon source, and optionally further heating the mixture, thereby forming a carbon coating on the active electrode material; (iii) spray drying the active electrode material; and / or (iv) milling the active electrode material to modify the particle size of the active electrode material; 34. The method of any one of aspects 27 to 33, comprising one or more post-treatment steps selected from:

Claims

1. General formula [M1] ｘ [M2] （１－ｘ） [Nb] ｙ [O] ｚ An active electrode material represented by: M1 and M2 are different, M1 represents one or more of Ti, Mg, V, Cr, W, Zr, Mo, Cu, Fe, Ga, Ge, Ca, K, Ni, Co, Al, Sn, Mn, Ce, Te, Se, Si, Sb, Y, La, Hf, Ta, Re, Zn, In, or Cd; M2 represents one or more of V, W, Zr, Mo, Ga, Ge, Al, Hf, Ta, or Zn; x satisfies 0<x<0.5, y satisfies 0.5≦y≦49, z satisfies 4≦z≦124, At least a portion of the active electrode material has a Wadsley-Roth crystal structure and / or a tetragonal tungsten bronze crystal structure; and The active electrode material wherein M1 has an oxidation state equal to or lower than M2.

2. 10. The active electrode material of claim 1, wherein M2 is selected from one or more of Mo, W, V, or Zr.

3. 3. The active electrode material of claim 1 or 2, wherein M1 represents one or more of K, Mg, Ca, Y, Ti, Zr, Hf, V, Ta, Cr, Mo, W, Mn, Fe, Co, Ni, Cu, Zn, Al, Ga, Si, Ge, Sn, Sb.

4. 3. The active electrode material of claim 1 or 2, wherein M1 represents one or more of Ti, Mg, V, Cr, W, Zr, Mo, Cu, Ga, Ge, K, Ni, Al, Hf, Ta, or Zn.

5. 3. The active electrode material of claim 1 or 2, wherein M1 represents one or more of Ti, Mg, V, Cr, W, Zr, Mo, Ga, Ge, Al, or Zn.

6. 6. The active electrode material of claim 1, wherein M1 has a lower oxidation state than M2.

7. 7. The active electrode material of claim 1, wherein M1 comprises at least one cation having an oxidation state of 4+ and M2 comprises at least one cation having an oxidation state of 6+.

8. 8. The active electrode material of claim 1, wherein M1 has an oxidation state of 4+ and M2 has an oxidation state of 6+.

9. The crystalline structure of the active electrode material, as determined by X-ray diffraction, corresponds to the crystalline structure of the active electrode material in its unmodified form, which is [M2][Nb] ｙ [O] ｚ wherein M2 consists of a single element, and the unmodified form is not oxygen deficient, and the unmodified form is Ｉ Nb ５ O １３ , M2 Ｉ ６ Nb １０．８ O ３０ , M2 ＩＩ Nb ２ O ６ , M2 ＩＩ ２ Nb ３４ O ８７ , M2 ＩＩＩ Nb １１ O ２９ , M2 ＩＩＩ Nb ４９ O １２４ , M2 ＩＶ Nb ２４ O ６２ , M2 ＩＶ Nb ２ O ７ , M2 ＩＶ ２ Nb １０ O ２９ , M2 ＩＶ ２ Nb １４ O ３９ , M2 ＩＶ Nb １４ O ３７ , M2 ＩＶ Nb ６ O １７ , M2 ＩＶ Nb １８ O ４７ , M2 Ｖ Nb ９ O ２５ , M2 Ｖ ４ Nb １８ O ５５ , M2 Ｖ ３ Nb １７ O ５０ , M2 ＶＩ Nb １２ O ３３ , M2 ＶＩ ４ Nb ２６ O ７７ , M2 ＶＩ ３ Nb １４ O ４４ , M2 ＶＩ ５ Nb １６ O ５５ , M2 ＶＩ ８ Nb １８ O ６９ , M2 ＶＩ Nb ２ O ８ , M2 ＶＩ １６ Nb １８ O ９３ , M2 ＶＩ ２０ Nb ２２ O １１５ , M2 ＶＩ ９ Nb ８ O ４７ , M2 ＶＩ ８２ Nb ５４ O ３８１ , M2 ＶＩ ３１ Nb ２０ O １４３ , M2 ＶＩ ７ Nb ４ O ３１ , M2 ＶＩ １５ Nb ２ O ５０ , M2 ＶＩ ３ Nb ２ O １４ , and M2 ＶＩ １１ Nb １２ O ６３ and the numbers I, II, III, IV, V, and VI in the unmodified form represent the oxidation states of M2.

10. The active electrode material according to any one of claims 1 to 9, wherein x satisfies 0.01≦x≦0.

4.

11. The active electrode material according to any one of claims 1 to 9, wherein x satisfies 0.05≦x≦0.

25.

12. 10. The active electrode material of any one of claims 1 to 9, wherein x is about 0.

05.

13. The active electrode material according to any one of claims 1 to 12, wherein the active electrode material is oxygen deficient.

14. 14. The active electrode material of claim 13, wherein z is defined as z=(z'-z'α), and α satisfies 0<α≦0.

05.

15. 15. The active electrode material according to any one of claims 1 to 14, wherein at least 90% by volume of the active electrode material has a Wadsley-Roth crystal structure and / or a tetragonal tungsten bronze crystal structure.

16. 16. The active electrode material according to any one of claims 1 to 15, wherein the active electrode material comprises a plurality of primary crystallites, the primary crystallites having an average diameter of 10 nm to 10 μm.

17. 17. The active electrode material of claim 16, wherein some or all of the primary crystallites aggregate into secondary particles.

18. 18. The active electrode material of claim 17, wherein the average diameter of the secondary particles is 1 μm to 30 μm.

19. 17. The active electrode material of claim 16, wherein the active electrode material includes a carbon coating formed on the surfaces of the primary crystallites.

20. The active electrode material described in claim 17, wherein the active electrode material includes a carbon coating formed on the surfaces of the primary crystallites and the secondary particles.

21. 21. The active electrode material of claim 19 or 20, wherein the carbon coating is present in an amount of up to 5 w / w%, based on the total weight of the active electrode material.

22. The active electrode material has a thickness of 0.1 to 100 m. ２ 22. The active electrode material of any one of claims 1 to 21, having a BET surface area in the range of 1 / g.

23. The crystalline structure of the active electrode material as determined by X-ray diffraction analysis is MoNb １２ Oh ３３ WNb １２ O ３３ VNb ９ O ２５ Zrrｮb ２４ O ６２ W ７ Nb ４ O ３１ W ９ Nb ８ O ４７ Zn ２ Nb ３４ O ８７ Alllb １１ O ２９ GaNb １１ O ２９ Geｮb １８ O ４７ W １６ Nb １８ O ９３ W ５ Nb １６ O ５５ Alllb ４９ O １２４ GaNb ４９ O １２４ 23. An active electrode material according to any one of claims 1 to 22, which corresponds to one or more crystal structures of:

24. The crystalline structure of the active electrode material as determined by X-ray diffraction analysis is MoNb １２ Oh ３３ WNb １２ O ３３ VNb ９ O ２５ Zrrｮb ２４ O ６２ W ４ Nb ７ O ３１ W ９ Nb ８ O ４７ Zn ２ Nb ３４ O ８７ Alllb １１ O ２９ Geｮb １８ O ４７ 23. An active electrode material according to any one of claims 1 to 22, which corresponds to one or more crystal structures of:

25. The crystalline structure of the active electrode material as determined by X-ray diffraction analysis is MoNb １２ Oh ３３ WNb １２ O ３３ Zrrｮb ２４ O ６２ VNb ９ O ２５ W ７ Nb ４ O ３１ W ９ Nb ８ O ４７ 23. An active electrode material according to any one of claims 1 to 22, which corresponds to one or more crystal structures of:

26. The crystalline structure of the active electrode material is TiNb ２ O ７ 26. The active electrode material of claim 1, wherein the active electrode material does not correspond to the crystal structure of

27. 27. The active electrode material according to any one of claims 1 to 26, further comprising Li and / or Na.

28. 28. An electrochemical device comprising an anode, a cathode, and an electrolyte disposed between the anode and the cathode, wherein the anode comprises the active electrode material of any one of claims 1 to 27.

29. 28. A method for producing an active electrode material according to any one of claims 1 to 27, said method comprising: Providing one or more precursor materials; mixing the precursor materials to form a precursor material mixture; heat treating the precursor material mixture at a temperature ranging from 400°C to 1350°C to form the active electrode material; The method includes the steps of:

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