Electrochemical Cell

Abstract

The present invention provides an electrochemical cell, e.g., a lithium ion battery, including an anode, a cathode, and an electrolyte disposed between the anode and the cathode, the anode including a niobium-containing oxide as an active anode material, the niobium-containing oxide having a crystal structure of M II 2Nb 34 O 87 , M III Nb 11 O 29 , M III Nb 49 O 124 , M IV Nb 24 O 62 , M V NbO 25 , M VI Nb 12 O 33 , H-Nb2O5, or N-Nb2O5 crystal structures, and the cells have an N / P ratio >1 as defined herein.

Description

[Technical field]

[0001] The present invention relates to electrochemical cells containing a niobium-containing oxide as the active anode material. Such cells are of interest as metal-ion batteries, for example lithium-ion or sodium-ion batteries. [Background technology]

[0002] Lithium-ion (Li-ion) batteries are a type of commonly used rechargeable battery, with the global market predicted to grow to $200 billion by 2030. Li-ion batteries are the technology of choice for electric vehicles, which have multiple requirements from technical performance to environmental impact, providing a viable path towards 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 membrane (called a separator) and immersed in a liquid that allows the transport of lithium ions (called the electrolyte).

[0004] In most systems, the electrode is composed of an active electrode material, i.e., one that can chemically react with lithium ions to reversibly store and release them in a controlled manner, optionally mixed with conductive additives (e.g., carbon) and polymeric binders. A slurry of these components is applied as a thin film onto a current collector (usually a thin foil of copper or aluminum) and, after drying, forms the electrode. The active anode and cathode materials can form an electrochemical cell with a wide range of N / P ratios, calculated from the capacity of the individual half-cells of the active anode material at its first lithiation and the active cathode material at its first delithiation. N / P is believed to affect at least the life and safety of the cell. However, deriving the optimal N / P ratio is a complex process that depends on the properties of each active material.

[0005] In known Li-ion battery technologies, the safety limitations of graphite anodes during battery charging are a major obstacle to their application in high-power electronics, automotive and industrial applications. Among various promising alternatives recently proposed, lithium titanate oxide (LTO) and niobium-containing oxides are promising candidates to replace graphite as the optimal active material for high-power fast-charging applications.

[0006] Niobium-containing oxides have been known in the academic literature for some time, but only recently have there been increasing interest in their use in Li-ion cells. For example, WO2021 / 074593, WO2021 / 074594, WO2021 / 245411, and WO2021 / 245410 disclose various substituted and / or oxygen-deficient oxides containing niobium, which have been found to have good properties for use as active anode materials. However, there is a need to optimize electrochemical cells utilizing niobium-containing oxides to aid in the market uptake of these promising active anode materials. Summary of the Invention

[0007] In a first aspect, the present invention provides an electrochemical cell comprising an anode, a cathode, and an electrolyte disposed between the anode and the cathode; The anode comprises an oxide containing niobium as an active anode material, and the crystal structure of the oxide containing niobium is M II 2 Nb 34 O 87 , M III Nb 11 O 29 , M III Nb 49 O 124 , M IV Nb 24 O 62 , M V Nb 9 O 25 , M VI Nb 12 O 33 , H-Nb 2 O 5 , or N-Nb 2 O 5corresponds to the crystal structure of The cell has an N / P ratio >1, where the N / P ratio is:

number

[0008] The inventors have discovered that having N / P>1 for electrochemical cells containing certain active anode materials surprisingly results in improved stability and life compared to N / P<1, as shown in the examples. It is theorized that by designing the cell in this manner, the available cathode capacity is fully utilized, which allows control over the full cell voltage limit and may prevent an undesired increase in the active cathode material potential (i.e., the local voltage during full cell operation). As the cathode voltage increases, the active material may become lithium-rich, which may result in material decomposition, which may exceed the stability limits of the electrolyte in use and lead to further electrolyte decomposition reactions at the surface of the cathode material. Furthermore, it is believed that designing the cell with N / P>1 improves life and performance by minimizing side reactions that may occur at low voltages between the electrolyte and certain classes of active anode materials.

[0009] Preferably, the electrochemical cell is a metal ion battery, such as a lithium ion or sodium ion battery, most preferably a lithium ion battery. [Brief description of the drawings]

[0010] [Figure 1] For Example 1, the capacity fade is shown as a function of 1C / 1C cycle number. [Diagram 2] For Example 1, DCIR increase is shown as a function of cycle number. [Diagram 3] For Example 1, the baseline capacity loss is shown as a function of cycle number. [Figure 4] For Example 1, first cycle formation data is shown. [Diagram 5] For Example 1, a 10C charge rate test is shown. [Figure 6] For Example 1, a 10C discharge rate test is shown. [Figure 7] For Example 2, first cycle formation data is presented. [Figure 8] For Example 2, a 10C charge rate test is shown. [Figure 9] For Example 2, a 10C discharge rate test is shown. [Figure 10] For Example 3, first cycle formation data is presented. [Figure 11] For Example 3, a 10C charge rate test is shown. [Figure 12] For Example 3, a 10C discharge rate test is shown. [Figure 13] For Example 4, first cycle formation data is presented. [Figure 14] For Example 4, a 10C charge rate test is shown. [Figure 15] For Example 4, a 10C discharge rate test is shown. [Figure E1] Powder XRD of samples E1 to E4 is shown. [Figure E2] Powder XRD of samples E5 to E12 is shown. [Figure F1] Powder XRD of samples F1 to F4 is shown. [Figure F2] Powder XRD of samples F5 to F9 is shown. [Figure G1] Powder XRD of samples G1 to G9 is shown. [Figure G2] Powder XRD of samples G10 to G17 is shown. [Figure H1] 1 shows powder XRD of samples H1, H2, H5, H10, H13, H14, and H17. [Figure H2] Confocal Raman spectra of samples H2, H13, H15, H16, and H17 are shown. To collect the spectra, laser excitation 532 nm, attenuation 10% and magnification 50 were used on a Horiba Xplora Plus Raman microscope, and the samples were pressed into a pellet at 10 MPa pressure and placed on a glass slide. Spectra were recorded in the spectral range 0-2500 cm-1 with an average collection time of 15 seconds per scan, three repetitions, and three different sample positions. [Figure I1] 1 shows powder XRD of samples I1, I2, I4, I5, I8, I9, I10, I11, and I12. [Figure I2] 1 shows powder XRD of samples I6 and I7. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] N / P is defined as:

number

[0012] Active fraction (wt %) is the percentage of the dry electrode composition that is the active material, e.g., 91 wt % NMC622 in the cathode used in the examples.

[0013] Initial lithiation / delithiation capacity (mAhg -1) is the specific capacity at C / 10 at 25° C. for the first lithiation cycle of the anode or the first delithiation cycle of the cathode measured in an equivalent half-cell with a Li metal counterelectrode. An equivalent half-cell can be understood to utilize the same electrode composition deposited at the same areal loading and active fraction as the full cell.

[0014] The charge rate of a cell is usually expressed as a "C-rate". A 1C charge rate means a charging current such that the cell is fully charged in 1 hour, and a 10C charge means that the battery is fully charged in 1 / 10 of an hour (6 minutes). The C-rate may be defined in terms of the reversible capacity of the cell within the appropriate voltage limits. For example, a 1.0 mAhcm2 charge rate within the voltage limits of 1.2 to 3.15 V is -2 For a cell with a capacity of 1.0mAcm, the 1C rate is 1.0mAcm -2 corresponds to the applied current density of

[0015] The first lithiation / delithiation capacity is measured on equivalent half-cells. For the anode, the first constant current C / 10 lithiation (discharge, negative current) capacity (vs Li / Li+) at 25° C. is measured. For the cathode, the first constant current C / 10 delithiation (charge, positive current) capacity (vs Li / Li+) at 25° C. is measured.

[0016] N / P is greater than 1, for example ≧1.01. N / P can be >1 to 2, or in the range of 1.01 to 1.5, or preferably in the range of 1.05 to 1.3.

[0017] The active anode and cathode materials chemically react with metal ions, preferably lithium ions, allowing them to be reversibly stored and released in a controlled manner. Oxides containing niobium have a high redox voltage of >0.8V vs. lithium, allowing safe and long-life operation, essential for fast charging of battery cells. In addition, the niobium cation can exhibit two redox reactions per atom, resulting in a higher theoretical capacity than, for example, LTO. Oxides containing niobium and at least one other cation are sometimes referred to as mixed niobium oxides.

[0018] The crystal structures of the niobium-containing oxides utilized in the present invention can be classified as Wadsley-Roth crystal structures. These include MO including crystallographic shear. 3 (ReO 3 ), which is believed to be the crystallographic off-stoichiometry of the crystal structure of 3-x As a result, these structures are usually simplified to [MO 6 Materials with these structures are believed to have advantageous properties for use as active electrode materials, for example, in lithium-ion batteries. For example, the open tunnel-like MO 3 The crystal structure makes them ideal candidates for having high capacity Li-ion storage and high rates of intercalation / deintercalation.

[0019] The crystal structure of a material can be identified by analyzing X-ray diffraction (XRD) patterns, as is widely known. For example, the XRD pattern obtained from a given material can be compared to known XRD patterns, for example, via a public database such as the ICDD crystallography database, to confirm the crystal structure. Rietveld and Pauly analyses can also be used to identify the crystal structure of a material, particularly with respect to unit cell parameters. Thus, an oxide containing niobium can have a crystal structure that corresponds to a particular crystal structure identified by X-ray diffraction. The term "corresponding" can be understood to reflect that peaks in the X-ray diffraction pattern may be shifted by 0.5 degrees or less (preferably, by 0.25 degrees or less, and more preferably, by 0.1 degrees or less) from corresponding peaks in the X-ray diffraction pattern of a reference pattern for the crystal structure.

[0020] Reference patterns for the crystal structures utilized in the present invention are available at: M II 2 Nb 34 O 87 For example, Zn 2 Nb 34 O 87 , ICDD Crystallographic Database Entry JCPDS 28-1478 M III Nb 11 O 29 For example, AlNb 11 O 29 , ICDD Crystallographic Database Entry JCPDS 22-009 M III Nb 49 O 124 For example, FeNb 49 O 124 , ICDD Crystallographic Database Entry JCPDS 22-0351 M IV Nb 24 O 62 For example, ZrNb 24 O 62 , ICDD Crystallographic Database Entry JCPDS 01-072-1655 M V Nb 9 O 25 For example, PNb 9 O 25 , ICDD Crystallographic Database Entry JCPDS 81-1304 M VI Nb 12 O 33 For example, WNb 12 O 33 , ICDD Crystallographic Database Entry JCPDS 73-1322 H-Nb 2 O 5 :ICDD Crystallographic Database Entry JCPDS 37-1468 N-Nb 2 O 5 :Andersson, S., Zeitschrift fur anorganische und allgemeine Chemie 1967 Vol.351;Iss.1-2;The Crystal Structure of N-Nb 2 O 5 ,prepared in the presence of small amounts of LiF

[0021] The crystal structure of the niobium-containing oxide may optionally be II 2 Nb 34 O 87 , M III Nb 11 O 29 , M V Nb 9 O 25 , or H-Nb 2 O 5 Corresponding to or M II 2 Nb 34 O 87 , M III Nb 11 O 29 , or H-Nb 2 O 5 Most preferably, the crystal structure of the niobium-containing oxide corresponds to M II 2Nb 34 O 87 The crystal structure of, for example, Zn 2 Nb 34 O 87 This corresponds to the crystal structure of

[0022] The niobium-containing oxide is preferably in the form of a fine particle. The niobium-containing oxide has a diameter of D ranging from 0.1 to 100 μm, or from 0.5 to 50 μm, or from 1 to 20 μm. 50 These particle sizes are advantageous because they are easy to process and manufacture into electrodes. Furthermore, these particle sizes eliminate the need to use complex and / or expensive methods to produce nano-sized particles. Nano-sized particles (e.g., D of 100 nm or less) can be used. 50 Particles with a particle size of 100 nm or less are usually more complicated to synthesize and require additional safety considerations.

[0023] The niobium-containing oxide has a D of at least 0.05 μm, or at least 0.1 μm, or at least 0.5 μm, or at least 1 μm. 10 D 10 By maintaining particle size within these ranges, the potential for parasitic reactions in Li-ion cells is reduced by having a reduced surface area and facilitating processing with less binder in the electrode slurry.

[0024] The niobium-containing oxide has a D of 200 μm or less, 100 μm or less, 50 μm or less, or 20 μm or less. 90 D 90 By maintaining the particle size within these ranges, the proportion of the particle size distribution with larger particle sizes is minimized, making it easier to fabricate the material into a homogenous electrode.

[0025] The term "particle size" refers to the equivalent spherical diameter (esd), i.e., the diameter of a sphere having the same volume as a given particle, which particle volume is understood to include the volume of any intraparticle voids. n " and "D nThe term "particle size" refers to the diameter below which n% by volume of the particle population is found, i.e., "D 50 " and "D 50 "Particle size" refers to the volume-based median particle size below which 50% by volume of the particle population is found. When a material contains primary crystallites aggregated into secondary particles, it is understood that the particle size refers to the diameter of the secondary particles. Particle size may be measured by laser diffraction. Particle size may be measured in accordance with ISO13320:2009, for example using Mie theory.

[0026] The oxide containing niobium is 0.1 to 100 m 2 / g, or 0.2 to 50m 2 / g, or 0.5 to 20m 2 The niobium oxide may have a BET surface area of ​​up to 1000 nm / g. In general, a low BET surface area is preferred to minimize the reaction between the niobium oxide and the electrolyte, for example, to minimize the formation of a solid electrolyte interface (SEI) layer during the first charge-discharge cycle of an electrode containing the material. However, a BET surface area that is too low will result in unacceptably low charge rate and capacity, since most of the niobium oxide will not be accessible to metal ions in the surrounding electrolyte.

[0027] The term "BET surface area" refers to 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, the BET surface area can be determined according to ISO 9277:2010.

[0028] The niobium-containing oxide may be coated with carbon, for example, to improve surface electronic conductivity and / or to prevent reaction with the electrolyte.

[0029] The niobium-containing oxide may have a protective coating, optionally comprising niobium oxide, aluminum oxide, zirconium oxide, organic or inorganic fluorides, organic or inorganic phosphates, titanium oxide, lithiated forms thereof, and mixtures thereof.

[0030] The anode and cathode are generally in the form of an electrode composition (i.e., an anode composition or a cathode composition) in electrical contact with a current collector. The current collector is usually a metal foil, such as copper or aluminum foil.

[0031] Optionally, the niobium-containing oxide forms at least 5%, 10%, 50%, or 75% by weight of the total active anode material of the anode. The niobium-containing oxide may form the only active anode material of the anode.

[0032] The electrode composition may further include at least one other component selected from a binder, a conductive additive, a different active electrode material, and mixtures thereof. For example, one anode composition includes about 92 wt. % of an oxide comprising niobium, about 5 wt. % of a conductive additive (e.g., carbon black), and about 3 wt. % of a binder (e.g., polyvinyldifluoride), based on the total dry weight of the anode composition.

[0033] Examples of suitable binders include polyvinylidene fluoride and its copolymers (PVDF), polytetrafluoroethylene (PTFE) and its copolymers, polyacrylonitrile (PAN), poly(methyl)methacrylate or poly(butyl)methacrylate, polyvinyl chloride (PVC), polyvinyl formal, polyetheramide, polymethacrylic acid, polyacrylamide, polyitaconic acid, polystyrene sulfonic acid, polyacrylic acid (PAA) and its alkali metal salts, modified polyacrylic acid (mPAA) and its alkali metal salts, cellulosic polymers, carboxymethylcellulose (CMC), modified carboxymethylcellulose (mCMC), sodium carboxymethylcellulose (Na-CMC), polyvinyl alcohol (PVA), alginates and their alkali metal salts, butadiene acrylonitrile rubber (NBR), hydrogenated form of NBR (HNBR), styrene butadiene rubber (SBR), and polyimides. The binder may be present in the electrode composition in an amount of 0 to 30 wt %, or 0.1 to 10 wt %, or 0.1 to 5 wt %, based on the total dry weight of the electrode composition.

[0034] The conductive additive is preferably a non-active material contained to improve electrical conductivity between active electrode materials and between the active electrode material and the current collector. The conductive additive may be appropriately selected from graphite, carbon black, carbon fiber, vapor grown carbon fiber (VGCF), carbon nanotubes, graphene, acetylene black, ketjen black, metal fiber, metal powder, and conductive metal oxide. Preferred conductive additives include carbon black and carbon nanotubes. The conductive additive may be contained in the electrode composition in an amount of 0 to 20% by weight, 0.1 to 10% by weight, or 0.1 to 5% by weight, based on the total dry weight of the electrode composition.

[0035] The active electrode material may be present in the electrode composition at 100-50 wt%, 99.8-80 wt%, or 99.8-90 wt%, based on the total dry weight of the electrode composition. When the active electrode material is present in 100 wt% of the electrode composition, it may form a solid electrode.

[0036] When a different active anode material is included in addition to the niobium-containing oxide, it may be selected from lithium titanium oxide, titanium niobium oxide, different mixed niobium oxides, graphite, hard carbon, soft carbon, silicon, doped versions thereof, and mixtures thereof.

[0037] The niobium oxide can be synthesized by conventional ceramic techniques.For example, it can be made by one or more of solid-state synthesis or sol-gel synthesis.The niobium oxide can also be synthesized by one or more of commonly used alternative techniques, such as hydrothermal or microwave hydrothermal synthesis, solvothermal or microwave solvothermal synthesis, co-precipitation synthesis, spark plasma or microwave plasma synthesis, combustion synthesis, electrospinning, spray pyrolysis, chemical vapor deposition, atomic layer deposition, and mechanical alloying.

[0038] The niobium-containing oxide may be provided by a method including the steps of obtaining 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 range of 400° C. to 1350° C. or 800 to 1250° C. to obtain the niobium-containing oxide.

[0039] To provide an oxide comprising niobium and a further electronegative anion other than oxygen, the method may further comprise the steps of mixing the oxide comprising niobium with a precursor comprising a further electronegative anion to obtain a further precursor material mixture, and heat treating the further precursor material mixture at a temperature in the range of 300-1200° C. or 800-1100° C., optionally under reducing conditions, to obtain the oxide comprising niobium and the further electronegative anion.

[0040] For example, to provide an oxide comprising niobium and N, the method further includes the steps of mixing the niobium-containing oxide with a precursor comprising N (e.g., melamine or urea) to obtain a further precursor material mixture, and reducing the further precursor material mixture at a temperature range of 300-1200° C. under reducing conditions (e.g., N2 The method may include a step of obtaining an oxide containing niobium and N by heat treating the niobium-containing oxide at a temperature below 200° C.

[0041] For example, to provide an oxide comprising niobium and F, the method further comprises reacting the niobium-containing oxide with a precursor comprising F (e.g., polyvinylidene fluoride or NH 4 F) to obtain a further precursor substance mixture, and heat treating the further precursor substance mixture at a temperature range of 300 to 1200° C. under oxidizing conditions (e.g., in air) to obtain an oxide containing niobium and F.

[0042] The method may include a further step of inducing oxygen vacancies in the niobium-containing oxide by heat treating the niobium-containing oxide under reducing conditions in the temperature range of 400 to 1350°C or 800 to 1250°C.

[0043] The precursor materials for making the niobium-containing oxides may include one or more metal oxides, metal hydroxides, metal salts, or ammonium salts. For example, the precursor materials may include one or more metal oxides or metal salts of different oxidation states and / or different crystal structures. Examples of suitable precursor materials include Nb 2 O 5 , Nb(OH) 5 , Niobic acid, NbO, Ammonium oxalate niobate, NH 4 H 2 PO 4 , (NH 4 ) 2 PO 4 , (NH 4 ) 3 PO 4 , P 2 O 5 , H 3 PO 3 , Ta 2 O 5 , WO 3 , ZrO 2 , TiO 2 , MoO 3 , V 2 O 5 , ZrO2 , CuO, ZnO, Al 2 O 3 , K 2 O, KOH, CaO, GeO 2 , Ga 2 O 3 , SnO 2 , CoO, Co 2 O 3 , Fe 2 O 3 , Fe 3 O 4 , MnO, MnO 2 , NiO, Ni 2 O 3 , H 3 BO 3 , ZnO, Li 2 CO 3 , Na 2 CO 3 , H 3 BO 3 , NiO, Mg 5 (CO 3 ) 4 (OH) 2 .5H 2 The precursor materials may include, but are not limited to, metal oxides, such as ions of metal salts (e.g., NO, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59 3 - , S.O. 3 - ) or other compounds (e.g., oxalates, carbonates). When replacing the oxygen anion with other electronegative anions, the precursor may include one or more organic compounds, polymers, inorganic salts, organic salts, gases, or ammonium salts, examples of which include melamine, NH 4 HCO 3 , N.H. 3 , N.H. 4 F, PVDF, PTFE, NH 4 Cl, NH 4 Br, N.H. 4 I, Br 2 , Cl 2 , I 2 , ammonium oxychloride amide, and hexamethylenetetramine.

[0044] Some or all of the precursor materials may be particulate materials. If they are particulate materials, then preferably they have a diameter of less than 20 μm, for example a D of 10 nm to 20 μm. 50 The particulate material may have an initial particle size of <20 μm in diameter, however, since the particle size of the one or more precursor materials may be mechanically reduced during the step of mixing the precursor materials to form a precursor material mixture.

[0045] The step of mixing the precursor materials to form the precursor material mixture and / or further precursor material mixture may be performed by a process selected from dry or wet / solvated planetary ball milling, rolling ball milling, high energy ball milling, bead milling, pin milling, a classification step, high shear milling, air jet milling, steam jet milling, planetary mixing, powder dosing, and / or impact milling. The force used for mixing / milling may depend on the morphology of the precursor materials. For example, if some or all of the precursor materials are mixed with larger particle sizes (e.g., D > 20 μm), the precursor materials may be mixed with a larger particle size (e.g., D > 20 μm). 50 When the precursor material has a particle size of 20 μm or less, the milling force may be selected to reduce the particle size of the precursor material mixture such that the particle size of the precursor material mixture is reduced to 20 μm or less in diameter. When the particle size of the particles in the precursor material mixture is 20 μm or less, the solid-state reaction of the precursor material in the precursor material mixture during the heat treatment step may be promoted more efficiently. The solid-state synthesis may be performed on pellets formed at high pressure (>10 MPa) from the precursor powder.

[0046] The step of heat treating the precursor material mixture and / or the further precursor material mixture may be carried out for a period of from 1 hour to 24 hours, more preferably from 3 hours to 18 hours. For example, the heat treating step may 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 may be carried out for 24 hours or less, 18 hours or less, 16 hours or less, or 12 hours or less.

[0047] The step of heat treating the precursor material mixture may be carried out in a gas atmosphere, preferably air. Suitable gas atmospheres include air, N 2 , Ar, He, CO 2 , C.O., O 2 , H 2 , N.H. 3 and mixtures thereof. The gas atmosphere may be a reducing atmosphere. If it is desired to create an oxygen deficient material, preferably the step of heat treating the precursor material mixture is carried out in an inert or reducing atmosphere.

[0048] The step of heat treating the further precursor material mixture may be carried out under reducing conditions, including under an inert gas, such as nitrogen, helium, argon, or a mixture of an inert gas and hydrogen, or under vacuum. Preferably, the step of heat treating the further precursor material mixture comprises heating under an inert gas.

[0049] The further step of heat treating the niobium-containing oxide and / or the niobium-containing oxide and further electronegative anion, optionally under reducing conditions, may be carried out for 0.5 hours to 24 hours, more preferably 2 hours to 18 hours. For example, the heat treatment step may be carried out for 0.5 hours or more, 1 hour or more, 3 hours or more, 6 hours or more, or 12 hours or more. The heat treatment of the further step may be carried out for 24 hours or less, 18 hours or less, 16 hours or less, or 12 hours or less. Reducing conditions include under an inert gas, such as nitrogen, helium, argon, or a mixture of inert gas and hydrogen, or under vacuum. Preferably, heating under reducing conditions includes heating under an inert gas.

[0050] In some methods, it may be beneficial to carry out a two-step heat treatment. For example, the precursor material mixture and / or the further precursor material mixture may 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 may support a solid-state reaction to form the desired crystal structure. This may be done consecutively or with an intermediate regrinding step.

[0051] The method may include one or more post-treatment steps after the formation of the niobium-containing oxide. In some cases, the method may include a post-treatment step, sometimes called "annealing", of heat-treating the niobium-containing oxide. 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 niobium-containing oxide. The post-treatment heat-treatment step may be performed in an inert gas atmosphere or a reducing gas atmosphere. Such a post-treatment heat-treatment step may be performed at a temperature above 500°C, for example about 900°C. Including a post-treatment heat-treatment step may be beneficial, for example, in inducing oxygen vacancies in the niobium-containing oxide or in forming vacancies or defects for anion exchange in the formed niobium-containing oxide, for example, for exchanging O anions with N.

[0052] The method may include milling and / or classifying the niobium-containing oxide (e.g., impact milling, jet milling, steam jet milling, high energy milling, high shear milling, pin milling, air classification, wheel classification, sieving, cyclone separation, bead milling) to obtain a material having any of the particle size parameters above.

[0053] The cathode is LiNi where M=Co, Mn, Al. 1-x M x O 2The class of nickel-based layered oxides, such as NMC, i.e., lithium nickel manganese cobalt oxide, NCA, i.e., lithium cobalt aluminum oxide, and LCO, i.e., lithium cobalt oxide, and LNMO, i.e., lithium nickel manganese oxide (e.g., LiNi 0.5 Mn 1.5 O 4 For example, the active cathode material may be lithium nickel manganese cobalt oxide. NCA (lithium nickel cobalt aluminum oxide) is a preferred active cathode material. Active cathode materials are widely available from commercial suppliers. The active cathode material may be doped with additional cations and / or anions.

[0054] The choice of active electrode material may affect suitable voltage ranges, such as for determining initial lithiation / delithiation capacity. For example, suitable voltage ranges may be: LNMO: 5.2-3 V, with an upper cutoff of 5.2 V; NCA, NMC, and LCO: 4.5-2.7 V, with an upper cutoff of 4.5 V; niobium-containing oxides: 3-0 V, with a lower cutoff of 0 V. More narrow ranges may be: LNMO: 5-3 V, with an upper cutoff of 5 V; NCA, NMC, and LCO: 4.3-2.7 V, with an upper cutoff of 4.3 V; niobium-containing oxides: 3 V-1.0 V, with a lower cutoff of 1.0 V.

[0055] The appropriate voltage range can be experimentally determined. For example, the voltage profile correlates with the change in the energy state of the anodic and cathodic materials associated with the removal or insertion of electrons and ions. The cutoff voltage of the cell can be selected to fall before a certain inflection point in the voltage profile that corresponds to the energy state of one or both electrodes rising above a critical level, causing the crystal structure to collapse into a lower energy structure at a rate that is significantly detrimental to the performance of the cell. The absolute voltage at which this occurs is a function of the electrode potentials of both electrodes, but can be calculated using a common reference electrode and does not need to be experimentally determined for established families of materials with reliable standard electrochemical behavior.

[0056] The cathode active material is preferably in particulate form, for example having a D in the range of 0.1 to 100 μm, or 0.5 to 50 μm, or 1 to 20 μm. 50 It has a particle size.

[0057] The electrolyte may include any material suitable for the operation of a metal-ion battery, preferably a lithium-ion battery. For example, the electrolyte may be a non-aqueous solution (e.g., an organic electrolyte). The electrolyte may include one or more non-aqueous solvents and a salt that is at least partially dissolved in the solvent. For example, the solvent may include an organic solvent, such as ethylene carbonate (EC) and / or other carbonate-based solvents, or butyrate, or acetate, or a mixture thereof. The solvent may include an aprotic solvent mixture, such as 1M LiPF4 dissolved in a 1:1 by weight mixture of ethylene carbonate and other carbonate-based solvents or butyrate or acetate. 6 may include.

[0058] Suitable salts for use in the present invention include LiPF 6 , LiSbF 6 , LiBF 4 , LiTFSI, LiFSI, LiAlCl 4 , LiAsF 6 , LiClO 4 , LiGaCl 4 , LiC(SO 2 CF 3 ) 3 , LiN(CF 3 SO 2 ) 2 , Li(CF 3 SO 3 ), LiB(C 6 H 4 O 2 ) 2, LiBOB (lithium bis(oxalato)borate), and LiDFOB (lithium difluoro(oxalato)borate). Suitable low viscosity solvents (e.g., organic solvents) for use in the electrolyte may include, but are not limited to, ethyl methyl carbonate (EMC), dioxolane (DOL), ethyl acetate (EA), propylene acetate (PA), butyl acetate (BA), methyl butyrate (MB), ethyl butyrate (EB), dimethyl carbonate (DMC), diethyl carbonate (DEC), 1,2-dimethoxyethane (DME), tetrahydrofuran (THF), methyl acetate (MA), diglyme (DGL), triglyme, tetraglyme, cyclic carbonates, cyclic esters, cyclic amides, propylene carbonate (PC), methyl propyl carbonate (MPC), acetonitrile, dimethyl sulfoxide (DMS), dimethylformamide, dimethylacetamide, gamma-butyrolactone (GBL), and N-methylpyrrolidinone (NMP), as well as various mixtures or combinations thereof.

[0059] An electrode may be made by forming a slurry of the active electrode material and a solvent. The slurry may include at least one other component selected from a binder, a conductive additive, a different active electrode material, and mixtures thereof. The slurry may be deposited on a current collector and the solvent removed to form an electrode composition on the current collector. Optionally, further steps may be performed, such as heat treatment to cure any binder, and / or calendaring the electrode layer. For example, the solvent may be removed by drying, for example, at a temperature of 30-100°C. The electrode may have a density of 2-3.5 or 2.6-2.9 gcm. -3 The electrode layer may have a film thickness in the range of 5 μm to 2 mm, preferably 5 μm to 1 mm, preferably 5 μm to 500 μm, preferably 5 μm to 200 μm, preferably 5 μm to 100 μm, preferably 5 μm to 50 μm.

[0060] Alternatively, the slurry can be formed into a free-standing film or mat comprising the active electrode material, for example, by casting the slurry into a suitable casting mold, removing the solvent, and then removing the casting mold. The resulting film or mat is in the form of a coherent, free-standing mass, which can then be bonded to a current collector by known methods.

[0061] In a variation of the invention, when the anode comprises any of the niobium-containing oxides disclosed herein, the N / P ratio can be ≦1, for example, from 0.7 to 0.95.

[0062] formula 1 In a preferred embodiment, the niobium-containing oxide is represented by the formula M1 a M2 2-a M3 b Nb 34-b O 87-c-d Q d (Formula 1), wherein: M1 and M2 are different, M1 is selected from Mg, Ca, Sr, Y, La, Ce, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Fe, Co, Ni, Cu, Zn, Cd, B, Al, Ga, In, Si, Ge, Sn, Pb, P, Sb, Bi, and mixtures thereof; M2 is Zn or Cu; M3 is selected from Mg, Ca, Sr, Y, La, Ce, Ti, Zr, Hf, V, Ta, Cr, Mo, W, Mn, Fe, Co, Ni, Cu, Zn, Cd, B, Al, Ga, In, Si, Ge, Sn, Pb, P, Sb, Bi, and mixtures thereof; Q is selected from F, Cl, Br, I, N, S, Se, and mixtures thereof; 0≦a<1.0, 0≦b≦3.4, −0.5≦c≦4.35, 0≦d≦4.35, One or more of a, b, c, and d is not equal to 0; If a, b, and d are 0, then c is greater than 0.

[0063] Equation 1 is M II 2 Nb 34O 87 Thus, this formula and the other formulas below can be used to define the active anode materials used in the present invention without the need to define the crystal structure.

[0064] Equation 1 shows that stoichiometric Zn 2 Nb 34 O 87 or Cu 2 Nb 34 O 87 It will be understood that the Zn cations do not correspond to the Zn cations by incorporating additional cations (M1 and / or M3) and / or by creating induced oxygen deficiencies or excesses and / or by forming mixed anion species (containing O and Q). 2 Nb 34 O 87 or Cu 2 Nb 34 O 87 It has been found that by modifying the above, the resulting material has improved electrochemical properties, especially when used as an anode material. If a>0, formula 1 is modified by partial substitution of M2 (Zn or Cu) with M1. If b>0, formula 1 is modified by partial substitution of Nb with M3. If c≠0, formula 1 is modified by oxygen deficiency or excess. If d>0, formula 1 is modified by partial substitution of O with Q. As shown in this example, the inventors have found that the material described in formula 1 can be obtained by modifying the unmodified "base" Zn 2 Nb 34 O 87 They found that compared to , they have improved electronic conductivity, improved Coulombic efficiency, and improved delithiation voltage at high C rates.

[0065] Zinc 2 Nb 34 O 87 or Cu 2 Nb 34 O 87 is ReO 3 Origin of MO 3-xThe Wadsley-Roth crystal structure may be considered to have a crystal structure, such as a MO structure that includes crystallographic shear. 3 (ReO 3 ) crystal structure, and is considered to be the crystallographic off-stoichiometry of the formula MO 3-x As a result, these structures are usually simplified by the [MO 6 Materials having these structures are believed to have advantageous properties for use, for example, as active electrode materials in lithium ion batteries.

[0066] In addition, the open tunnel-like MOs of these materials 3 The crystal structure makes them ideal candidates for having high capacity Li-ion storage and high rates of intercalation / deintercalation. The crystallographic off-stoichiometry present in the crystal structure gives rise to Wadsley-Roth crystallographic superstructures. These superstructures, compounded by other properties such as the Jahn-Teller effect and more crystallographic disorder due to the use of multiple mixed cations, stabilize the crystals, keep them stable by opening tunnels during intercalation, and allow high Li-ion diffusion rates (approximately 10 -13 cm 2 s -1 (reported) allows for very high rates of performance.

[0067] Zinc 2 Nb 34 O 87 or Cu 2 Nb 34 O 87 The crystal formula is [MO 6 ] octahedra, where M is Cu, Zn, or Nb. The Cu and Zn octahedra may be randomly distributed within the structure or may prefer specific locations such as edges or corners of the blocks. This equates to one Zn or 2 / 3 Cu cation per block. Zn 2 Nb 34 O87 The crystal formula is Cu 2 Nb 34 O 87 It can be described as an isostructural phase of , with slight differences in some of the bond lengths and bond enthalpies.

[0068] Preferably, the crystal structure of the oxide of formula 1 as determined by X-ray diffraction is Zn 2 Nb 34 O 87 or Cu 2 Nb 34 O 87 , most preferably Zn 2 Nb 34 O 87 It can thus be seen that the "base" material has been modified without significantly affecting its crystal structure, which is believed to have advantageous properties for use as an active anode material. Zn 2 Nb 34 O 87 The crystal structure of can be found in ICDD crystallography database entry JCPDS 28-1478.

[0069] The cation / anion exchanged oxide of formula 1 may have unit cell parameters a, b, and c, where a is 15.52-15.58 Å, preferably 15.53-15.57 Å, b is 3.79-3.84 Å, preferably 3.80-3.83 Å, and c=20.53-20.66 Å, preferably 20.54-20.65 Å. The oxide of formula 1 may have unit cell parameters α and γ, each about 90°, preferably α=γ=90°, while β is 113.05-113.75 0 , preferably 113.08 to 113.69 0 The unit cell volume is 1115 to 1135 Å. 3 , preferably 1117 to 1133 Å 3 The unit cell parameters can be determined by X-ray diffraction. The oxide of formula 1 can have a crystallite size, as determined according to the Scherrer formula, of 5 to 150 nm, preferably 30 to 60 nm.

[0070] By "and mixtures thereof" it is intended that M1, M3, and Q may each represent two or more elements from the respective lists. Examples of such materials are Mg 0.1 Ge 0.1 Zinc 1.8 Nb 34 O 87.1 Here, M1 is Mg a’ Ge a’’ (a'+a''=a), M2 is Zn, a=0.2, b=0, c=-0.1, d=0. Here, c is the oxidation state of each cation in its normal oxidation state, i.e., Mg 2+ , Ge 4+ , Zn 2+ , and Nb 5+ The calculations are based on the assumption that

[0071] The exact values ​​of a, b, c, d within the defined ranges may be selected to provide a charge-balanced or substantially charge-balanced crystal structure. Additionally or alternatively, the exact values ​​of a, b, c, d within the defined ranges may be selected to provide a thermodynamically stable or thermodynamically metastable crystal structure.

[0072] If an exchange of cations or anions (i.e., Zn, Cu, Nb, O) in the structure is performed without preserving the original valence, this can result in both oxygen deficiencies and excesses. For example, to some extent Zn 2+ Ge 4+ The replacement material has a slight oxygen excess (i.e., ZnO vs. GeO 2 ), while Nb 5+ Al 3+ The substitution with Nb 2 O 5 Against Al 2 O 3 ) Oxygen deficiencies can also be induced by heat treatment under inert or reducing conditions, resulting in the induction of oxygen vacancy defects in the structure.

[0073] There may be partial oxidation or partial reduction that compensates for the exchange, without retaining the original valence. For example, Zn 2+ Ge 4+ Substitution by Nb 5+ From Nb 4+ This can be at least partially compensated for by a reduction to

[0074] M2 is Zn or Cu. Preferably, M2 is Zn, in which case the material is Zn 2 Nb 34 O 87 Based on.

[0075] M1 is a cation that substitutes for M2 in the crystal structure. M1 may be selected from Mg, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Fe, Co, Ni, Cu, Zn, Cd, B, Al, Ga, Si, Ge, Sn, P, and mixtures thereof, preferably Mg, Ti, Zr, V, Nb, Cr, Mo, W, Mn, Fe, Co, Ni, Cu, Zn, B, Al, Si, Ge, P, and mixtures thereof, most preferably Mg, Zr, V, Cr, Mo, W, Fe, Cu, Zn, Al, Ge, P, and mixtures thereof. M1 is selected from M2 2+ This results in an oxygen deficiency or excess. Optionally, M1 can have a valence different from M2 2+ has a valence equal to or higher than, and preferably a valence higher than,

[0076] M1 may also be selected from each of the specific elements used by itself in the reference examples.

[0077] When multiple elements are present as M1 or M3, it will be understood that the valence refers to M1 or M3 as a whole. For example, if 25 atomic % of M1 is Ti and 75 atomic % of M1 is W, then the valence of M1 is 0.25 x 4 (contribution from Ti) + 0.75 x 6 (contribution from W).

[0078] M1 is preferably M2 2+, most preferably has a smaller ionic radius than Zn. This causes a change in unit cell size and local distortion in the crystal structure, resulting in the advantages discussed herein. The ionic radii referred to herein are the Shannon ionic radii (available in RD Shannon, Acta Cryst., A32, 1976, 751-767) of the coordination and valence that the ion is expected to adopt in the crystal structure of the niobium-containing oxide. For example, Zn 2 Nb 34 O 87 The crystal structure of Nb 5+ O 6 Octahedron and Zn 2+ O 6 Thus, when M3 is Zr, the ionic radius is 6-coordinate Zr 4+ This is considered to be the ionic radius of Zn 2 Nb 34 O 87 This is because of the normal valence and coordination of Zr when substituting Nb in

[0079] The amount of M1 is determined by a and meets the criteria 0≦a<1.0. a can be 0≦a≦0.6, preferably 0≦a≦0.2. Most preferably a>0, for example a≧0.01. If M1 has the same valence as M2, a higher value of a can be more easily achieved. If M1 contains a cation with a valence of 2+ (e.g., Mg), a can be 0≦a<1.0. If M1 does not contain a cation with a valence of 2+, a can be 0≦a≦0.15.

[0080] M3 is a cation that substitutes for Nb in the crystal structure. M3 may be selected from Mg, Ti, Zr, Hf, V, Ta, Cr, Mo, W, Mn, Fe, Co, Ni, Cu, Zn, Cd, B, Al, Ga, Si, Sn, P, and mixtures thereof, preferably Mg, Ti, Zr, V, Cr, Mo, W, Mn, Fe, Co, Ni, Cu, Zn, Cd, B, Al, Si, P, and mixtures thereof, most preferably Ti, Zr, V, Cr, Mo, W, Fe, Cu, Zn, Al, P, and mixtures thereof. M3 is Nb5+ This results in an oxygen deficiency or excess. Preferably, M3 is Nb 5+ It has a lower valence, which gives rise to the presence of oxygen deficiencies, i.e., oxygen vacancies, which provide the advantages discussed herein.

[0081] M3 may also be selected from each of the specific elements used by itself in the reference examples.

[0082] M3 is preferably Nb 5+ and most preferably has a larger ionic radius than, which causes a change in the unit cell size and local distortions in the crystal structure, resulting in the advantages discussed herein.

[0083] Optionally, M1 does not include Nb and M3 does not include Zn and / or Cu.

[0084] The amount of M3 is determined by b and satisfies the criterion 0≦b≦3.4. b may be 0≦b≦1.5, preferably 0≦b≦0.3. In each of these cases, b may be >0, for example b≧0.01. M3 is Nb 5+ When M3 has the same valence as M, higher values ​​of b can be more easily achieved. When M3 includes a cation with a valence of 5+ (e.g., Ta), b can be 0≦b≦3.4. When M3 does not include a cation with a valence of 5+, b can be 0≦b≦0.2.

[0085] Surprisingly, it has been found that the cation substitution approach according to formula 1 can result in niobium-containing oxides that are more economically synthesized than the unmodified "base" material. Preferably, both a and b are >0. When both a and b are >0, the "base" material is substituted at both the M2 and Nb positions.

[0086] c reflects the oxygen content of the niobium-containing oxide. When c is greater than 0, it forms an oxygen-deficient material, i.e., the material has oxygen vacancies. Such materials do not have exact charge balance without changing the oxygen state of the cations, but are considered to be "substantially charge-balanced" as described above. Alternatively, c may be equal to 0, in which case it is not an oxygen-deficient material. c may be less than 0, which is an oxygen-excess material. c may be -0.25≦c≦4.35.

[0087] When c is 4.35, the number of oxygen vacancies corresponds to 5% of the total oxygen in the crystal structure. c can be greater than 0.0435, greater than 0.087, greater than 0.174, or greater than 0.435. c can be 0-2, 0-0.75, 0-0.5, or 0-0.25. For example, c can satisfy 0.01≦c≦4.35. When the material is oxygen deficient, e.g., has induced oxygen vacancies, the electrochemical properties of the material can be improved, e.g., resistance measurements can show improved electrical conductivity compared to a comparable non-oxygen deficient material. As will be understood, the percentage values ​​expressed herein are atomic percents.

[0088] The present invention relates to niobium-containing oxides that may contain oxygen vacancies (oxygen-deficient oxides containing niobium) or may have an oxygen excess. Oxygen vacancies may be formed in niobium-containing oxides by sub-valent substitution of the base material as described above, and oxygen excess may arise in niobium-containing oxides by valence-increasing substitution. Oxygen vacancies may also be formed by heating niobium-containing oxides under reducing conditions, which may be referred to as the formation of induced oxygen vacancies. The amount of oxygen vacancies and excess is determined based on the total amount of oxygen in the base material, i.e., the amount of oxygen in the non-substituted material (e.g., Zn 2 Nb 34 O 87 )

[0089] There are several methods to determine whether oxygen vacancies, e.g., oxygen vacancies, exist in a material. For example, thermogravimetric analysis (TGA) may be performed to measure the mass change of a material when heated in an air atmosphere. A material containing oxygen vacancies may gain mass when heated in air as the material "reoxidizes" and the oxygen vacancies are filled with oxide anions. The magnitude of the mass increase may be used to quantify the concentration of oxygen vacancies contained in the material, assuming that the mass increase is entirely due to oxygen vacancies being filled. It should be noted that a material containing oxygen vacancies may show an initial mass increase as the oxygen vacancies are filled, and then lose mass when the material undergoes pyrolysis at a higher temperature. Furthermore, the mass loss and mass gain processes may overlap, i.e., some materials containing oxygen vacancies may not show mass gain (and in some cases, neither mass loss nor mass gain) during TGA analysis.

[0090] Other methods of determining whether oxygen vacancies, e.g., oxygen vacancies, are present include Raman spectroscopy, electron paramagnetic resonance (EPR), X-ray photoelectron spectroscopy (XPS, e.g., XPS of oxygen 1s and / or XPS of cations of mixed oxides), X-ray absorption near edge structure (XANES, e.g., XANES of cations of mixed metal oxides), and TEM (e.g., scanning TEM (STEM) equipped with high angle annular dark field (HAADF) and annular bright field (ABF) detectors). The presence of oxygen vacancies can be qualitatively determined by evaluating the color of a material, which indicates a change in its electronic band structure through interaction with light, compared to a non-oxygen deficient sample of the same material. For example, non-oxygen deficient stoichiometric Zn 2 Nb 34 O 87 Zn has a white color. 2 Nb 34 O <87 has a grey / black colour. The presence of vacancies can also be inferred from the properties, e.g. electrical conductivity, of a stoichiometric material compared to the properties of an oxygen deficient material.

[0091] When d>0, an additional anion Q is introduced into the niobium-containing oxide. Their different electronic structures (i.e., F - vs. O 2- ), and different ionic radii (6-coordinate O 2- =1.40Å, 6-coordinate F - =1.33 Å), they can improve the electrochemical performance of the active material. This is due to modifying the properties of the unit cell with different ionic radii, allowing for improved Li-ion capacity or improved Coulombic efficiency due to improved reversibility. They can further improve electrical conductivity by modifying the electronic structure of the crystal with respect to oxygen vacancies or subvalent cation substitutions (i.e., doping effect). d can be 0≦d≦3.0, or 0≦d≦2.17. In each of these cases, d can be >0. Q can be selected from F, Cl, N, S, and mixtures thereof, or F, N, and mixtures thereof, or Q is F.

[0092] Optionally, d=0, in which case Equation 1 becomes M1 a M2 2-a M3 b Nb 34-b O 87-c where M1, M2, M3, a, b, and c are as defined herein. Advantageously, materials with d=0 do not contain the anion Q and may be easier to synthesize.

[0093] If a>0 and b=d=0, Equation 1 is M1 a M2 2-a Nb 34 O 87-c where M1, M2, a, and c are as defined herein, e.g., 0≦c≦4.35. This represents a material modified at the M2 position, and optionally modified with induced oxygen vacancies. Such a material can be obtained by adding the "base" oxide M2 2 Nb 34 O 87represents a particularly effective way to improve the properties of by simple synthesis means, where M1 may represent Ti, Mg, V, Cr, W, Zr, Mo, Cu, Ga, Ge, Ni, Al, Hf, Ta, Zn, and mixtures thereof, preferably Ti, Mg, V, Cr, W, Zr, Mo, Ga, Ge, Al, Zn, and mixtures thereof.

[0094] If a=b=d=0 and c>0, then formula 1 represents the composition M2 2 Nb 34 O 87-c where M2 and c are as defined herein. This represents a material modified only by inducing oxygen vacancies, resulting in improved properties as shown in the examples. For example, a material with a=b=d=0 and c>0 has been surprisingly found to have improved electronic conductivity.

[0095] It will be understood that the descriptions of the variables (M1, M2, M3, Q, a, b, c, and d) in formula 1 are intended to be taken in combination. For example, preferably, M1 is selected from Mg, Ti, Zr, V, Nb, Cr, Mo, W, Mn, Fe, Co, Ni, Cu, Zn, B, Al, Si, Ge, P, and mixtures thereof, M3 is selected from Mg, Ti, Zr, V, Cr, Mo, W, Mn, Fe, Co, Ni, Cu, Zn, Cd, B, Al, Si, P, and mixtures thereof, and Q is selected from F, Cl, N, S, and mixtures thereof. Preferably, 0≦a≦0.6, 0≦b≦1.5, 0≦c≦4.35, and 0≦d≦3.0.

[0096] For example, Equation 1 is a M2 2-a M3 b Nb 34-b O 87-c-d Q d In the formula, M1 and M2 are different, M1 is selected from Mg, Ti, Zr, V, Nb, Cr, Mo, W, Mn, Fe, Co, Ni, Cu, Zn, B, Al, Si, Ge, P, and mixtures thereof; M2 is Zn or Cu; M3 is selected from Mg, Ti, Zr, V, Cr, Mo, W, Mn, Fe, Co, Ni, Cu, Zn, Cd, B, Al, Si, P, and mixtures thereof; Q is selected from F, N, and mixtures thereof; 0≦a≦0.6, 0≦b≦1.5, −0.5≦c≦4.35, 0≦d≦4.35, One or more of a, b, c, and d is not equal to 0; If a, b, and d are 0, then c is greater than 0.

[0097] M1, M3, and Q may also be selected from each of the specific elements used as these dopants in the embodiments.

[0098] Optionally, the oxide of formula 1 does not include titanium.

[0099] In a particularly preferred embodiment, Formula 1 is a Zinc 2-a M3 b Nb 34-b O 87-c In the formula, M1 is selected from Mg, Zr, V, Cr, Mo, W, Fe, Cu, Al, Ge, P, and mixtures thereof; M3 is selected from Ti, Zr, V, Cr, Mo, W, Fe, Cu, Zn, Al, P, and mixtures thereof; 0 <a<1.0、0<b≦3.4、-0.5≦c≦4.35である。

[0100] Equation 1 is M1 a M2 2-a M3 b Nb 34-b O 87-c In the formula, M1 is selected from Cr, Al, Ge, and mixtures thereof, preferably M1 is Cr; M2 is Zn or Cu, preferably M2 is Zn; M3 is selected from Ti, Zr, Fe, and mixtures thereof, optionally containing Ti, preferably, M3 is selected from Ti, Zr, and mixtures thereof, optionally containing Ti, and most preferably, M3 is Ti, 0 < a < 1.0, preferably, 0.01 < a < 1.0, 0 < b ≦ 1.5, preferably, 0.01 < b < 1.0, -0.5 ≦ c ≦ 4.35, preferably, -0.5 ≦ c ≦ 2, and most preferably, c = 0.

[0101] Formula 1 may be Cr a Zn 2-a M3 b Nb 34-b O 87-c and in which, M3 is selected from Ti, Zr, and mixtures thereof, optionally containing Ti, preferably, M3 is Ti, 0.01 < a < 1.0, preferably, 0.1 < a < 1.0, 0.01 < b < 1.0, preferably, 0.1 < b < 1.0, -0.5 ≦ c ≦ 2, preferably, c = 0.

[0102] The oxide of Formula 1 may further contain Li and / or Na. For example, Li and / or Na may enter the crystal structure when the niobium-containing oxide is used as an electrode in a metal ion battery.

[0103] Formula 2 The niobium-containing oxide may have the formula M4 a Al 1-a M5 b Nb 11-b O 29-c-d Q d (Formula 2), in which, M4 is selected from Mg, Ca, Sr, Y, La, Ce, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Fe, Co, Ni, Cu, Zn, Cd, B, Ga, In, Si, Ge, Sn, Pb, P, Sb, Bi, and mixtures thereof, M5 is selected from Mg, Ca, Sr, Y, La, Ce, Zr, Hf, V, Ta, Cr, Mo, W, Mn, Fe, Co, Ni, Cu, Zn, Cd, B, Al, Ga, In, Si, Ge, Sn, Pb, P, Sb, Bi, and mixtures thereof; Q is selected from F, Cl, Br, I, N, S, Se, and mixtures thereof; 0≦a<0.5, 0≦b≦1, −0.5≦c≦1.45, 0≦d≦1.45, One or more of a, b, and d is not equal to 0.

[0104] Equation 2 is M III Nb 11 O 29 4 shows an example of a niobium-containing oxide having a crystal structure corresponding to the crystal structure of

[0105] Equation 2 represents the stoichiometric AlNb 11 O 29 It will be appreciated that the present invention does not correspond to AlNb by incorporating additional cations (M4 and / or M5) and / or by forming mixed anion materials (containing O and Q) and, optionally, by creating induced oxygen deficiencies or excesses. 11 O 29 It has been discovered that by modifying the above, the resulting material has improved electrochemical properties, especially when used as an anode material. If a>0, formula 2 is modified by partial substitution of Al with M4. If b>0, formula 2 is modified by partial substitution of Nb with M5. If c≠0, formula 2 is modified by a deficiency or excess of oxygen. If d>0, formula 2 is modified by partial substitution of O with Q. As shown in this example, the inventors have found that the material described in formula 2 can be obtained by modifying the unmodified "base" AlNb 11 O 29We found that the specific capacity is improved and the capacity retention at high C-rates is improved compared to that of Nb-N ... 3+ Since Nb is not redox active, it is surprising that Formula 2 has superior properties for use as an active electrode material as demonstrated by this example. Typical prior approaches have focused on transition metals such as Cr and Fe that are redox active as the primary non-Nb cation.

[0106] AlNb 11 O 29 is ReO 3 Origin of MO 3-x It can be considered to have a crystal structure, for example the Wadsley-Roth crystal structure. 11 O 29 The crystal structure of [MO 6 ] octahedra, where M is Al or Nb. The Al octahedra may be randomly distributed within the structure or may prefer specific locations such as edges or corners of the blocks. This equates to one Al cation per block.

[0107] Preferably, the crystal structure of the oxide of formula 2 as determined by X-ray diffraction is AlNb 11 O 29 It can thus be seen that the "base" material has been modified without significantly affecting its crystal structure, which is believed to have advantageous properties for use as an active electrode material. 11 O 29 The crystal structure of can be found in ICDD crystallography database entry JCPDS 22-009.

[0108] The cation / anion exchanged oxide of formula 2 may have unit cell parameters a, b, and c, where a is 15.52-15.58 Å, preferably 15.53-15.57 Å, b is 3.79-3.83 Å, preferably 3.80-3.82 Å, and c=20.51-20.55 Å, preferably 20.52-20.54 Å. The oxide of formula 2 may have unit cell parameters α and γ, each about 90°, preferably α=γ=90°, while β is 113.00-113.70°, preferably 113.05-113.68°, and the unit cell volume is 1116-1120 Å. 3 , preferably 1117 to 1119 Å 3 The unit cell parameters can be determined by X-ray diffraction. The oxide of formula 2 can have a crystallite size, as determined according to the Scherrer formula, of 5 to 150 nm, preferably 40 to 70 nm.

[0109] By "and mixtures thereof" it is intended that M4, M5, and Q may each represent two or more elements from the respective lists. Examples of such materials are Zn 0.05 Ga 0.05 Al 0.9 Nb 11 O 28.975 Here, M4 is Zn a’ Ga a’’ (a'+a''=a), where a=0.1, b=0, c=0.025, and d=0. Here, c is the oxidation state of each cation in its normal oxidation state, i.e., Zn 2+ , Ga 3+ , Al 3+ The calculations are based on the assumption that

[0110] The exact values ​​of a, b, c, d within the defined ranges may be selected to provide a charge-balanced or substantially charge-balanced crystal structure. Additionally or alternatively, the exact values ​​of a, b, c, d within the defined ranges may be selected to provide a thermodynamically stable or thermodynamically metastable crystal structure.

[0111] If exchange of cations or anions (i.e. Al, Nb, O) within the structure is performed without preserving the original valence, this can result in both oxygen deficiencies and excesses. 3+ Ge 4+ The material to be replaced by Al is slightly oxygen-excessive (i.e., 2 O 3 vs. GeO 2 ), while Nb 5+ Al 3+ The substitution with Nb 2 O 5 Against Al 2 O 3 ) Oxygen deficiencies can also be induced by heat treatment under inert or reducing conditions, resulting in the induction of oxygen vacancy defects in the structure.

[0112] There may be partial oxidation or partial reduction that compensates for the exchange without preserving the original valence. For example, Al 3+ Ge 4+ Substitution by Nb 5+ From Nb 4+ This can be at least partially compensated for by a reduction to

[0113] M4 is a cation that substitutes Al in the crystal structure. M4 may be selected from Mg, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Fe, Co, Ni, Cu, Zn, Cd, B, Ga, Si, Ge, Sn, P, and mixtures thereof, preferably Mg, Zr, V, Cr, Mo, W, Mn, Fe, Co, Ni, Cu, Zn, B, Ga, Si, Ge, P, and mixtures thereof, most preferably Mg, Zr, Mo, W, Cu, Zn, Ga, Ge, P, and mixtures thereof. M4 is Al 3+ This results in an oxygen deficiency or excess. Optionally, M4 is Al 3+ has a valence equal to or lower than, preferably a lower valence than.

[0114] M4 may also be selected from each of the specific elements used in the reference examples by itself. For example, preferably, M4 is Ga.

[0115] When multiple elements are present as M4 or M5, it will be understood that the valence refers to M4 or M5 as a whole. For example, if 25 atomic % of M4 is Zr and 75 atomic % of M4 is W, then the valence of M4 is 0.25 x 4 (contribution from Zr) + 0.75 x 6 (contribution from W).

[0116] M4 is preferably Al 3+ , most preferably has a larger ionic radius than AlNb. This causes a change in the unit cell size and local distortions in the crystal structure, resulting in the advantages discussed herein. The ionic radii referred to herein are the Shannon ionic radii (available in RD Shannon, Acta Cryst., A32, 1976, 751-767) of the coordination and valence that the ion is expected to adopt in the crystal structure of formula 2. For example, AlNb 11 O 29 The crystal structure of Nb 5+ O 6 Thus, when M5 is Zr, the ionic radius is 6-coordinate Zr 4+ This is considered to be the ionic radius of AlNb 11 O 29 This is because of the normal valence and coordination of Zr when substituting Nb in

[0117] The amount of M4 is determined by a and satisfies the criterion 0≦a<0.5. a can be 0≦a≦0.4, preferably 0≦a≦0.2. Most preferably, a>0, for example, a≧0.01. M4 is Al 3+ When M4 has the same valence as M, higher values ​​of a can be more easily achieved. When M4 contains a cation with a valence of 3+ (e.g., Ga), a can be 0≦a<0.5. When M4 does not contain a cation with a valence of 3+, a can be 0≦a≦0.1.

[0118] M5 is a cation that substitutes for Nb in the crystal structure. M5 may be selected from Mg, Zr, Hf, V, Ta, Cr, Mo, W, Mn, Fe, Co, Ni, Cu, Zn, Cd, B, Al, Ga, Si, Sn, P, and mixtures thereof, preferably Mg, Zr, V, Cr, Mo, W, Mn, Fe, Co, Ni, Cu, Zn, Cd, B, Al, Si, P, and mixtures thereof, most preferably Zr, V, Cr, Mo, W, Fe, Cu, Zn, Al, P, and mixtures thereof. M5 is Nb 5+ This results in an oxygen deficiency or excess. Preferably, M5 is Nb 5+ It has a lower valence, which gives rise to the presence of oxygen deficiencies, i.e., oxygen vacancies, which provide the advantages discussed herein.

[0119] M5 may also be selected from each of the specific elements used by itself in the reference examples.

[0120] M5 is preferably Nb 5+ and most preferably has a larger ionic radius than, which causes a change in the unit cell size and local distortions in the crystal structure, resulting in the advantages discussed herein.

[0121] The amount of M5 is determined by b and satisfies the criterion 0≦b≦1. b may be 0≦b≦0.5, preferably 0≦b≦0.1. In each of these cases, b may be >0, for example b≧0.01. M5 is Nb 5+ When M5 has the same valence as M, higher values ​​of b can be more easily achieved. When M5 contains a cation with a valence of 5+ (e.g., Ta), b can be 0≦b≦1. When M5 does not contain a cation with a valence of 5+, b can be 0≦b≦0.05.

[0122] Optionally, both a and b are > 0. When both a and b are > 0, the "base" material is substituted at both the Al and Nb positions.

[0123] c reflects the oxygen content in formula 2. When c is greater than 0, it forms an oxygen-deficient material, i.e., the material has oxygen vacancies. Such materials are considered to be "substantially charge-balanced" as described above, although they do not have exact charge balance without changing the oxygen state of the cations. Alternatively, c may be equal to 0, in which case it is not an oxygen-deficient material. c may be less than 0, which is an oxygen-excess material. c may be -0.25≦c≦1.45.

[0124] When c is 1.45, the number of oxygen vacancies corresponds to 5% of the total oxygen in the crystal structure. c can be greater than 0.0145, greater than 0.029, greater than 0.0435, or greater than 0.145. c can be 0-1, 0-0.75, 0-0.5, or 0-0.25. For example, c can satisfy 0.01≦c≦1.45. When the material is oxygen deficient, e.g., has induced oxygen deficiencies, the electrochemical properties of the material can be improved, e.g., resistance measurements can show improved electrical conductivity compared to a comparable non-oxygen deficient material. As will be understood, percentage values ​​expressed herein are atomic percents.

[0125] When d>0, additional anions Q are introduced into formula 2. Their different electronic structures (i.e., F - vs. O 2- ), and different ionic radii (6-coordinate O 2- =1.40Å, 6-coordinate F -=1.33 Å), they can improve the electrochemical performance of the active material. This is due to modifying the properties of the unit cell with different ionic radii, allowing for improved Li-ion capacity or improved Coulombic efficiency due to improved reversibility. They can further improve electrical conductivity by modifying the electronic structure of the crystal, with respect to oxygen vacancies or subvalent cation substitutions (i.e., doping effect). d can be 0≦d≦1.0, or 0≦d≦0.7. In each of these cases, d can be >0, e.g., ≧0.01. Q can be selected from F, Cl, N, S, and mixtures thereof, or F, N, and mixtures thereof, or Q is F.

[0126] Optionally, d=0, in which case Equation 2 becomes M4 a Al 1-a M5 b Nb 11-b O 29-c where M4, M5, a, b, and c are as defined herein. Advantageously, materials with d=0 do not contain the anion Q and may be easier to synthesize.

[0127] If a>0 and b=d=0, then formula 2 represents the composition M4 a Al 1-a Nb 11 O 29-c where M4, a, and c are as defined herein, e.g., 0≦c≦1.45. This represents a material modified at the Al site, and optionally modified with induced oxygen vacancies. Such a material is a material similar to the "base" oxide AlNb 11 O 29 represents a particularly effective way to improve the properties of by simple synthetic means, where M4 may represent Mg, V, Cr, W, Zr, Mo, Cu, Ga, Ge, Ni, Hf, Ta, Zn, and mixtures thereof, preferably Mg, V, Cr, W, Zr, Mo, Ga, Ge, Zn, and mixtures thereof.

[0128] It will be understood that the descriptions of the variables (M4, M5, Q, a, b, c, and d) in formula 2 are intended to be taken in combination. For example, preferably, M4 is selected from Mg, Zr, V, Cr, Mo, W, Mn, Fe, Co, Ni, Cu, Zn, B, Ga, Si, Ge, P, and mixtures thereof, M5 is selected from Mg, Zr, V, Cr, Mo, W, Mn, Fe, Co, Ni, Cu, Zn, Cd, B, Al, Si, P, and mixtures thereof, and Q is selected from F, Cl, N, S, and mixtures thereof. Preferably, 0≦a≦0.4, 0≦b≦0.5, 0≦c≦1.45, and 0≦d≦1.0.

[0129] For example, Equation 2 is M4 a Al 1-a M5 b Nb 11-b O 29-c-d Q d In the formula, M4 is selected from Mg, Zr, V, Cr, Mo, W, Mn, Fe, Co, Ni, Cu, Zn, B, Ga, Si, Ge, P, and mixtures thereof; M5 is selected from Mg, Zr, V, Cr, Mo, W, Mn, Fe, Co, Ni, Cu, Zn, Cd, B, Al, Si, P, and mixtures thereof; Q is selected from F, Cl, N, S, and mixtures thereof; 0 <a≦0.4、0≦b≦0.5、-0.25≦c≦1.45、0≦d≦1.45である。

[0130] For example, Equation 2 is M4 a Al 1-a Nb 11 O 29-c-d Q d In the formula, M4 is selected from Mg, Zr, V, Cr, Mo, W, Mn, Fe, Co, Ni, Cu, Zn, B, Ga, Si, Ge, P, and mixtures thereof, preferably M4 is selected from Zr, Cr, Zn, Ga, and mixtures thereof; Q is selected from F, N, and mixtures thereof, preferably Q is F; 0 <a<0.5、0≦c≦1.45、0≦d≦1.45である。

[0131] For example, Equation 2 is M4 a Al 1-a Nb 11 O 29-c-d Q d In the formula, M4 is selected from Mg, Zr, Mo, W, Cu, Zn, Ga, Ge, P, and mixtures thereof, preferably M4 is selected from Zr, Zn, Ga, and mixtures thereof; Q is selected from F, N, and mixtures thereof, preferably Q is F; 0 <a≦0.2、0≦c≦1.45、0≦d≦1.45である。

[0132] M4, M5, and Q may also be selected from each of the specific elements used as these dopants in the embodiments.

[0133] The oxide of formula 2 may further include Li and / or Na. For example, Li and / or Na may enter the crystal structure when the oxide is used in an electrode of a metal-ion battery.

[0134] formula 3 The niobium-containing oxide has the formula M6 a P x-a M7 b Nb 9-b O 25-c-d Q d (Formula 3), wherein M6 is selected from Na, K, Mg, Ca, Sr, Y, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Fe, Co, Ni, Cu, Zn, B, Al, Ga, Si, Ge, Sn, Bi, Sb, and mixtures thereof; M7 is selected from Na, K, Mg, Ca, Sr, Y, Ti, Zr, Hf, V, Ta, Cr, Mo, W, Mn, Fe, Co, Ni, Cu, Zn, B, Al, Ga, Si, Ge, Sn, Bi, P, Sb, and mixtures thereof; Q is selected from F, Cl, Br, I, N, S, Se, and mixtures thereof; 0≦a≦0.5, 0≦b≦2, −0.5≦c≦1.25, 0≦d≦5, 1≦x≦2, One or more of a, b, c, and d is not equal to 0; With the proviso that when M6 consists of Nb and M7 consists of P, c is >0.

[0135] Equation 3 is M V Nb 9 O 25 4 shows an example of a niobium-containing oxide having a crystal structure corresponding to the crystal structure of

[0136] Equation 3 shows that stoichiometric PNb 9 O 25 It will be appreciated that the present invention does not correspond to PNb by incorporating additional cations (M6 and / or M7) to form mixed cation active electrode materials, and / or by creating induced oxygen deficiencies or excesses, and / or by forming mixed anion active electrode materials (containing O and Q). 9 O 25 By modifying a material containing PNb, the resulting material has improved electrochemical properties, particularly when used as an anode material. For example, the inventors have found that, as shown in this example, the material described in formula 3 has improved electrochemical properties, particularly when used as an anode material. 9 O 25 We found that the capacity retention at high C-rates is significantly improved compared to that of the materials described in Equation 3. This is an important result in demonstrating the advantages of the materials described in Equation 3 for use in batteries designed for high charge / discharge rates.

[0137] PNb 9 O 25 is ReO 3 Origin of MO 3-x It can be considered to have a crystal structure, e.g., the Wadsley-Roth crystal structure. 9 O 25 The crystal structure of can be described as having a 3x3x∞ crystallographic block structure with corner-sharing tetrahedra. 2.5 Nb 18 O50 The crystal formula is PNb 9 O 25 This can be described as an isostructural phase with PO, with slight differences in some bond lengths due to additional P (e.g., PO and Nb3-O2, Nb2-O2). This has previously been reported as a phosphate bronze material, but there is no clear correlation between it and the related theorized structure (i.e., P 2-4 Nb 18 O 50 ) is considered herein to be a distorted Wadsley-Roth crystal structure.

[0138] Preferably, the crystal structure of formula 3 as determined by X-ray diffraction is PNb 9 O 25 , VNb 9 O 25 , or P 2.5 Nb 18 O 50 One or more of, or PNb 9 O 25 Or P 2.5 Nb 18 O 50 or, most preferably, PNb 9 O 25 It corresponds to the crystal structure of PNb 9 O 25 The crystal structure of VNb can be found in ICDD Crystallography Database entry JCPDS 81-1304. 9 O 25 The crystal structure of can be found in JCPDS 49-0289. 2.5 Nb 18 O 50The crystal structure of can be found in ICDD 01-082-0081. The oxide of formula 3 can have unit cell parameters a, b, and c, where a is 15.4-15.8 Å, preferably 15.5-15.7 Å, b is 15.4-15.8 Å, preferably 15.5-15.7 Å, and c=3.6-4.0 Å, preferably 3.7-3.9 Å. Most preferably, a=b. The oxide of formula 3 can have unit cell parameters α, β, and γ, each of which is about 90°, preferably α=β=γ=90°. The unit cell parameters can be determined by X-ray diffraction. The oxide of formula 3 can have a crystallite size of 10-100 nm, preferably 30-60 nm, as determined according to the Scherrer formula.

[0139] By "and mixtures thereof" it is intended that M6, M7, and Q may each represent two or more elements from the respective lists. Examples of such materials are Ti 0.05 Mo 0.05 P 0.90 Nb 9 O 25 Here, M6 is Ti a’ Mo a’’ (a'+a''=a), where a=0.1, b=0, c=0, and d=0. Another example of such a material is Al 0.05 P 0.95 Ti 0.225 Mo 0.225 Nb 8.55 O 24.95 Here, M6 is Al a and M7 is Ti b’ Mo b’’ (b'+b''=b), where a=0.05, b=0.45, c=0.05, and d=0.

[0140] The exact values ​​of a, b, c, d within the defined ranges may be selected to provide a charge-balanced or substantially charge-balanced crystal structure. Additionally or alternatively, the exact values ​​of a, b, c, d within the defined ranges may be selected to provide a thermodynamically stable or thermodynamically metastable crystal structure.

[0141] If an exchange of cations or anions (i.e., P, Nb, O) within the structure occurs without preserving the original valence, this can result in both oxygen deficiencies and excesses. 5+ Mo 6+ The substitute for the oxygen is a slight excess (i.e., P 2 O 5 Against MoO 3 ), while P 5+ Al 3+ The substitution for is a small oxygen vacancy (i.e., P 2 O 5 Against Al 2 O 3 ) Oxygen deficiencies can also be induced by heat treatment under inert or reducing conditions, resulting in the induction of oxygen vacancy defects in the structure.

[0142] M6 is a cation substituting for P in the crystal structure. M6 may be selected from Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Fe, Co, Ni, Cu, Zn, B, Al, Ga, Si, Ge, Sn, Bi, Sb, and mixtures thereof, or Ti, Zr, Hf, Cr, Mo, W, B, Al, Ga, Bi, Sb, and mixtures thereof, or Ti, Mo, Al, B, and mixtures thereof. Preferably, M6 is not Nb. Preferably, M6 is not Na. M6 is not P 5+ This results in an oxygen deficiency or excess. Preferably, M6 is P 5+ M6 preferably has a lower valence than P, which causes oxygen deficiencies, i.e., the presence of oxygen vacancies, which provide the advantages discussed herein. 5+ and most preferably has a larger ionic radius than, which causes a change in the unit cell size and local distortions in the crystal structure, resulting in the advantages discussed herein.

[0143] The ionic radii referred to herein are the Shannon ionic radii for the coordination and valence that the ion is expected to adopt in the crystal structure of the active electrode material. For example, PNb 9 O 25 The crystal structure of Nb 5+ O 6 Octahedron and P 5+ O 4 Contains tetrahedrons.

[0144] The amount of M6 is determined by a and satisfies the criterion 0≦a≦0.5. a may be 0≦a≦0.3, preferably 0≦a≦0.2. In each of these cases, a may be >0, for example >0.01.

[0145] M7 is a cation substituting Nb in the crystal structure. M7 may be selected from Ti, Zr, Hf, V, Ta, Cr, Mo, W, Mn, Fe, Co, Ni, Cu, Zn, B, Al, Ga, Si, Ge, Sn, Bi, P, Sb, and mixtures thereof, or Ti, Zr, Hf, Cr, Mo, W, V, Ta, and mixtures thereof, or Ti, Mo, and mixtures thereof. Preferably, M7 is not P. Preferably, M7 is not Na. M7 is not Nb 5+ This results in an oxygen deficiency or excess. Preferably, M7 is Nb 5+ M7 preferably has a lower valence than Nb. This causes oxygen deficiencies, i.e., the presence of oxygen vacancies, which provide the advantages discussed herein. 5+ Preferably, the ionic radius is different from, and most preferably larger than, , which causes a change in the unit cell size and local distortions in the crystal structure, resulting in the advantages discussed herein.

[0146] The amount of M7 is determined by b, which satisfies the criterion 0≦b≦2. b may be 0≦b≦1.5, preferably 0≦b≦1, or 0≦b≦0.9. In each of these cases, b may be >0, for example >0.01.

[0147] Preferably, at least one of a and b is >0. Both a and b may be >0.

[0148] c reflects the oxygen content of the active electrode material. If c is greater than 0, it forms an oxygen deficient material, i.e., the material has oxygen vacancies. Such a material does not have exact charge balance without changing the oxygen state of the cations, but is considered to be "substantially charge balanced" as described above. Alternatively, c may be equal to 0, in which case it is not an oxygen deficient material. c may be less than 0, which is an oxygen excess material. c may be -0.25≦c≦1.25. Preferably, c is 0≦c≦1.25. Optionally, if a=b=0, c≧0, and preferably, if a=b=0, c>0.

[0149] When c is 1.25, the number of oxygen vacancies corresponds to 5% of the total oxygen in the crystal structure. c may be greater than 0.0125 (0.05% oxygen vacancies), 0.025 (0.1% oxygen vacancies), 0.05 (0.2% oxygen vacancies), or 0.125 (0.5% oxygen vacancies). c may be 0-1 (4% oxygen vacancies), 0-0.75 (3% oxygen vacancies), 0-0.5 (2% oxygen vacancies), or 0-0.25 (1% oxygen vacancies). For example, c may satisfy 0.01≦c≦1.25. When the material is oxygen deficient, the electrochemical properties of the material may be improved, e.g., resistance measurements may show improved electrical conductivity compared to a comparable non-oxygen deficient material. As will be understood, percentage values ​​expressed herein are atomic percents.

[0150] Equation 3 relates to phosphorus niobium oxide that may contain oxygen vacancies (oxygen deficient phosphorus niobium oxide) or may have oxygen excess. Oxygen vacancies may be formed in phosphorus niobium oxide by subvalent substitution of the base material as described above, and oxygen excess may be created in phosphorus niobium oxide by valence increasing substitution. Oxygen vacancies may be formed, optionally without cation substitution, by heating phosphorus niobium oxide under reducing conditions. Thus, Equation 3 represents P x Nb 9 O 25-c-d Q d where x, c, d, and Q are as defined herein. The amount of oxygen vacancies and excess is determined based on the total amount of oxygen in the base material, i.e., the amount of oxygen in the unsubstituted material (e.g., PNb 9 O 25 ) or the amount of oxygen in the material before heating under reducing conditions.

[0151] When d>0, an additional anion Q is introduced into the phosphorus niobium oxide. Their different electronic structures (i.e., F - vs. O 2- ), and different ionic radii (6-coordinate O 2- =1.40Å, 6-coordinate F - =1.33 Å), they can improve the electrochemical performance of the active material. This is due to modifying the properties of the unit cell with different ionic radii, allowing for improved Li-ion capacity or improved Coulombic efficiency due to improved reversibility. They can further improve electrical conductivity by modifying the electronic structure of the crystal with respect to oxygen vacancies or subvalent cation substitutions (i.e., doping effect). d can be 0≦d≦2.5, or 0≦d≦1. In each of these cases, d can be >0. Q can be selected from F, Cl, N, S, and mixtures thereof, or F, N, and mixtures thereof, or Q is N.

[0152] Optionally, d=0, in which case the material has composition M6 a P x-a M7 b Nb9-b O 25-c where M6, M7, a, b, c, and x are as defined herein. Advantageously, materials with d=0 do not contain the anion Q and may be easier to synthesize.

[0153] x reflects the amount of phosphorus contained in the material and satisfies the criterion 1≦x≦2. x can be 1≦x≦1.25. Preferably, x=1. When x=1, Equation 3 becomes PNb 9 O 25 Based on the crystal structure of

[0154] It will be understood that the descriptions of the composition variables (M6, M7, Q, a, b, c, d, and x) are intended to be taken in combination. For example, preferably, M6 is selected from Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Fe, Co, Ni, Cu, Zn, B, Al, Ga, Si, Ge, Sn, Bi, Sb, and mixtures thereof, and M7 is selected from Ti, Zr, Hf, V, Ta, Cr, Mo, W, Mn, Fe, Co, Ni, Cu, Zn, B, Al, Ga, Si, Ge, Sn, Bi, P, Sb, and mixtures thereof. M6 can be selected from Ti, Zr, Hf, Cr, Mo, W, B, Al, Ga, Bi, Sb, and mixtures thereof, and M7 can be selected from Ti, Zr, Hf, Cr, Mo, W, V, Ta, and mixtures thereof. M6 may be selected from Ti, Mo, Al, B, and mixtures thereof, and M7 may be selected from Ti, Mo, and mixtures thereof. M6 is preferably not Nb, and M7 is preferably not P. M6 and M7 are preferably not Na. M6 and M7 may be different. a may be 0≦a≦0.3, and b may be 0≦b≦1.5. Preferably, 0≦a≦0.2 and 0≦b≦1. In each of these cases, a and / or b may be >0.

[0155] For example, formula 3 is M6 a P x-a M7 b Nb 9-b O 25-c-d Q d In the formula, M6 is selected from Ti, Zr, Hf, V, Ta, Cr, Mo, W, Mn, Fe, Co, Ni, Cu, Zn, B, Al, Ga, Si, Ge, Sn, Bi, Sb, and mixtures thereof; M7 is selected from Ti, Zr, Hf, V, Ta, Cr, Mo, W, Mn, Fe, Co, Ni, Cu, Zn, B, Al, Ga, Si, Ge, Sn, Bi, Sb, and mixtures thereof; Q is selected from F, Cl, N, S, and mixtures thereof; 0≦a≦0.3, 0≦b≦1.5, -0.25≦c≦1.25, 0≦d≦2.5, 1≦x≦1.25, One or more of a, b, c, and d is not equal to 0.

[0156] For example, formula 3 is M6 a P 1-a M7 b Nb 9-b O 25-c-d Q d In the formula, M6 is selected from Ti, Zr, Hf, V, Ta, Cr, Mo, W, Mn, Fe, Co, Ni, Cu, Zn, B, Al, Ga, Si, Ge, Sn, Bi, Sb, and mixtures thereof; M7 is selected from Ti, Zr, Hf, V, Ta, Cr, Mo, W, Mn, Fe, Co, Ni, Cu, Zn, B, Al, Ga, Si, Ge, Sn, Bi, Sb, and mixtures thereof; Q is selected from F, N, and mixtures thereof; 0≦a≦0.3, 0≦b≦1.5, 0≦c≦1.25, and 0≦d≦2.5; One or more of a, b, c, and d is not equal to 0.

[0157] For example, formula 3 is M6 a P 1-a M7 b Nb 9-b O 25-c-d Q d In the formula, M6 is selected from Ti, Zr, Hf, Cr, Mo, W, B, Al, Ga, Ge, Bi, Sb, and mixtures thereof; M7 is selected from Ti, Zr, Hf, Cr, Mo, W, V, Ta, Ga, Ge, and mixtures thereof; Q is selected from F, N, and mixtures thereof; 0≦a≦0.2, 0≦b≦1, 0≦c≦1.25, 0≦d≦2.5, At least one of a and b is >0.

[0158] formula 4 The niobium-containing oxide has the formula M8 a M9 1-a M10 b Nb 12-b O 33-c-d Q d (Formula 4), wherein The M8 and M9 are different. M8 is selected from Mg, Ca, Sr, Y, La, Ce, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Fe, Co, Ni, Cu, Zn, Cd, B, Al, Ga, In, Si, Ge, Sn, Pb, P, Sb, Bi, and mixtures thereof; M9 is Mo or W; M10 is selected from Mg, Ca, Sr, Y, La, Ce, Ti, Zr, Hf, V, Ta, Cr, Mo, W, Mn, Fe, Co, Ni, Cu, Zn, Cd, B, Al, Ga, In, Si, Ge, Sn, Pb, P, Sb, Bi, and mixtures thereof; Q is selected from F, Cl, Br, I, N, S, Se, and mixtures thereof; 0≦a<0.5, 0≦b≦2, −0.5≦c≦1.65, 0≦d≦1.65, One or more of a, b, c, and d is not equal to 0; If a, b, and d are 0, then c is greater than 0.

[0159] Equation 4 is M VI Nb 12 O 33 4 shows an example of a niobium-containing oxide having a crystal structure corresponding to the crystal structure of

[0160] Equation 4 shows that stoichiometric WNb12 O 33 or MoNb 12 O 33 It will be appreciated that the present invention does not correspond to the above-mentioned. The inventors have demonstrated that WNb by incorporating additional cations (M8 and / or M10) and / or by creating induced oxygen deficiencies or excesses and / or by forming mixed anion polar materials (containing O and Q). 12 O 33 or MoNb 12 O 33 We have found that by modifying the oxide, the resulting material has improved electrochemical properties, especially when used as an anode material. If a>0, the oxide is modified by partial substitution of M8 for M9 (Mo or W). If b>0, the oxide is modified by partial substitution of M10 for Nb. If c≠0, the oxide is modified by oxygen deficiency or excess. If d>0, the oxide is modified by partial substitution of Q for O. We have found that the modified oxides have significantly improved electronic conductivity, improved coulombic efficiency, and improved delithiation voltage at high C-rates compared to the unmodified "base" material, as shown in this example. This is an important result in demonstrating the advantages of the material of the invention when used in batteries designed for high rate charge / discharge.

[0161] MoNb 12 O 33 and WNb 12 O 33 is ReO 3 Origin of MO 3-x It can be considered to have a crystal structure, for example the Wadsley-Roth crystal structure. MoNb 12 O 33 or WNb 12 O 33 The crystal structure of WO 4 ] or [MoO 4 ]) and can be described as having a 3x4x∞ crystallographic block structure. 12 O 33 The crystal formula is MoNb12 O 33 It can be described as an isostructural phase of , with slight differences in some of the bond lengths.

[0162] Preferably, the crystal structure of the oxide of formula 4 as determined by X-ray diffraction is WNb 12 O 33 or MoNb 12 O 33 , most preferably MoNb 12 O 33 It can thus be seen that the "base" material has been modified without significantly affecting its crystal structure, which is believed to have advantageous properties for use as an active electrode material. 12 O 33 The crystal structure of can be found in ICDD crystallography database entry JCPDS 73-1322.

[0163] The cation / anion exchanged oxide of formula 4 may have unit cell parameters a, b, and c, where a is 22.23-22.43 Å, preferably 22.27-22.38 Å, b is 3.81-3.84 Å, preferably 3.82-3.84 Å, and c=17.7-17.9 Å, preferably 17.73-17.88 Å. The oxide of formula 4 may have unit cell parameters α and γ, each about 90°, preferably α=γ=90°, while β is 123.1-123.7 0 , preferably 123.2 to 123.65 0 The unit cell volume is 1260-1280Å. 3 , preferably 1264 to 1275 Å 3 The unit cell parameters can be determined by X-ray diffraction. The oxide of formula 4 can have a crystallite size, as determined according to the Scherrer formula, of 5 to 150 nm, preferably 30 to 60 nm.

[0164] By "and mixtures thereof" it is intended that M8, M10, and Q may each represent two or more elements from the respective lists. Examples of such materials are Ti 0.05 W0.25 Mo 0.70 Nb 11.95 Al 0.05 O 32.9 Here, M8 is Ti a’ W a’’ (a'+a''=a), M9 is Mo, M10 is Al, a=0.3, b=0.05, c=0.1, d=0. Here, c is the oxidation state of each cation in its normal oxidation state, i.e., Al. 3+ , Ti 4+ , W 6+ 、 Mo 6+ , and Nb 5+ The calculations are based on the assumption that

[0165] The exact values ​​of a, b, c, d within the defined ranges may be selected to provide a charge-balanced or substantially charge-balanced crystal structure. Additionally or alternatively, the exact values ​​of a, b, c, d within the defined ranges may be selected to provide a thermodynamically stable or thermodynamically metastable crystal structure.

[0166] When exchange of cations or anions (i.e., Mo, W, Nb, O) within the structure occurs without preserving the original valence, this can result in both oxygen deficiencies and excesses. For example, to some extent Nb 5+ Mo 6+ The replacement material is a slight excess of oxygen (i.e., Nb 2 O 5 Against MoO 3 ), while Nb 5+ Al 3+ The substitution for Nb 2 O 5 Against Al 2 O 3 ) Oxygen deficiencies can also be induced by heat treatment under inert or reducing conditions, resulting in the induction of oxygen vacancy defects in the structure.

[0167] There may be partial oxidation or partial reduction that compensates for the exchange without retaining the original valence. For example, Nb 5+ Al 3+ Substitution for some Nb 5+ From Nb 4+ This can be at least partially compensated for by a reduction to

[0168] M9 is Mo or W. Preferably, M9 is Mo, in which case the material is MoNb 12 O 33 Based on.

[0169] M8 is a cation that substitutes for M9 in the crystal structure. M8 may be selected from Mg, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Fe, Co, Ni, Cu, Zn, Cd, B, Al, Ga, Si, Sn, P, and mixtures thereof, preferably Mg, Ti, Zr, V, Nb, Cr, Mo, W, Mn, Fe, Co, Ni, Cu, Zn, Cd, B, Al, Si, P, and mixtures thereof, most preferably Ti, Zr, V, Cr, Mo, W, Fe, Cu, Zn, Al, P, and mixtures thereof. M8 is a cation that substitutes for M9 in the crystal structure. M8 may be selected from Mg, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Fe, Co, Ni, Cu, Zn, Cd, B, Al, Si, Sn, P, and mixtures thereof, most preferably Ti, Zr, V, Cr, Mo, W, Fe, Cu, Zn, Al, P, and mixtures thereof. 6+ This results in an oxygen deficiency or excess. Preferably, M8 is M9 6+ It has a lower valence, which gives rise to the presence of oxygen deficiencies, i.e., oxygen vacancies, which provide the advantages discussed herein.

[0170] M8 may also be selected from each of the specific elements used by itself in the reference examples.

[0171] When multiple elements are present as M8 or M10, it will be understood that the valence refers to M8 or M10 as a whole. For example, if 25 atomic % of M8 is Ti and 75 atomic % of M8 is W, then the valence of M8 is 0.25×4 (contribution from Ti)+0.75×6 (contribution from W).

[0172] M8 is preferably M9 6+, most preferably has a larger ionic radius than MoNb. This causes a change in the unit cell size and local distortions in the crystal structure, resulting in the advantages discussed herein. The ionic radii referred to herein are the Shannon ionic radii (available in RD Shannon, Acta Cryst., A32, 1976, 751-767) of the coordination and valence that the ion is expected to adopt in the crystal structure of formula 4. For example, MoNb 12 O 33 The crystal structure of Nb 5+ O 6 Octahedron and Mo 6+ O 4 Thus, when M10 is Zr, the ionic radius is 6-coordinate Zr 4+ This is considered to be the ionic radius of MoNb 12 O 33 This is because of the normal valence and coordination of Zr when substituting Nb in

[0173] The amount of M8 is determined by a, which meets the criterion 0≦a<0.5. a can be 0≦a≦0.45, preferably 0≦a≦0.3. Most preferably a>0, for example a≧0.01. The inventors have discovered that partial substitution of M9 for M8, as shown by this example, provides mixed niobium oxides with significantly improved properties compared to the unmodified "base" material. Higher values ​​of a can be more easily achieved when M8 has the same valence as M9. When M8 contains a cation with a valence of 6+ (e.g., Mo or W), a can be 0≦a<0.5. When M8 does not contain a cation with a valence of 6+, a can be 0≦a≦0.2.

[0174] M10 is a cation that substitutes for Nb in the crystal structure. M10 may be selected from Mg, Ti, Zr, Hf, V, Ta, Cr, Mo, W, Mn, Fe, Co, Ni, Cu, Zn, Cd, B, Al, Ga, Si, Sn, P, and mixtures thereof, preferably Mg, Ti, Zr, V, Cr, Mo, W, Mn, Fe, Co, Ni, Cu, Zn, Cd, B, Al, Si, P, and mixtures thereof, most preferably Ti, Zr, V, Cr, Mo, W, Fe, Cu, Zn, Al, P, and mixtures thereof. M10 is Nb 5+ This results in an oxygen deficiency or excess. Preferably, M10 is Nb 5+ It has a lower valence, which gives rise to the presence of oxygen deficiencies, i.e., oxygen vacancies, which provide the advantages discussed herein.

[0175] M10 may also be selected from each of the specific elements used by itself in the reference examples.

[0176] M10 is preferably Nb 5+ and most preferably has a larger ionic radius than, which causes a change in the unit cell size and local distortions in the crystal structure, resulting in the advantages discussed herein.

[0177] The amount of M10 is determined by b and satisfies the criterion 0≦b≦2. b may be 0≦b≦1.0, preferably 0≦b≦0.2. In each of these cases, b may be >0, for example b≧0.01. M10 is Nb 5+ When M10 has the same valence as M10, higher values ​​of b can be more easily achieved. When M10 contains a cation with a valence of 5+ (e.g., Ta), b can be 0≦b≦2. When M10 does not contain a cation with a valence of 5+, b can be 0≦b≦0.15.

[0178] c reflects the oxygen content in formula 4. When c is greater than 0, it forms an oxygen deficient material. Such a material may have oxygen vacancies. Such a material does not have exact charge balance without changing the oxygen state of the cations, but is considered to be "substantially charge balanced" as described above. Alternatively, c may be equal to 0, in which case it is not an oxygen deficient material. c may be less than 0, which is an oxygen excess material. c may be -0.25 ≦ c ≦ 1.65. Preferably, c is 0 ≦ c ≦ 1.65. For example, non-oxygen deficient stoichiometric MoNb 12 O 33 MoNb has a white, off-white, or yellow color. 12 O <33 has a purple color.

[0179] When c is 1.65, the number of oxygen vacancies corresponds to 5 atomic % of the total oxygen in the crystal structure. c can be greater than 0.0165, greater than 0.033, greater than 0.066, or greater than 0.165. c can be 0-1, 0-0.75, 0-0.5, or 0-0.25. For example, c can satisfy 0.01≦c≦1.65. When the material is oxygen deficient, the electrochemical properties of the material can be improved, e.g., resistance measurements can show improved electrical conductivity compared to a comparable non-oxygen deficient material.

[0180] When d>0, additional anions Q are introduced into formula 4. Their different electronic structures (i.e., F - vs. O 2- ), and different ionic radii (6-coordinate O 2- =1.40Å, 6-coordinate F -=1.33 Å), they can improve the electrochemical performance of the active material. This is due to modifying the properties of the unit cell with different ionic radii, allowing for improved Li-ion capacity or improved Coulombic efficiency due to improved reversibility. They can further improve electrical conductivity by modifying the electronic structure of the crystal, with respect to oxygen vacancies or subvalent cation substitutions (i.e., doping effect). d can be 0≦d≦1.0, or 0≦d≦0.8. In each of these cases, d can be >0, e.g., d≧0.01. Q can be selected from F, Cl, N, S, and mixtures thereof, or F, N, and mixtures thereof, or Q is N.

[0181] Optionally, d=0, in which case Equation 4 becomes M8 a M9 1-a M10 b Nb 12-b O 33-c where M8, M9, M10, a, b, and c are as defined herein. Advantageously, materials with d=0 do not contain the anion Q and may be easier to synthesize.

[0182] It is understood that the descriptions of the composition variables (M8, M9, M10, Q, a, b, c, and d) are intended to be taken in combination. For example, preferably, M8 is selected from Mg, Ti, Zr, V, Nb, Cr, Mo, W, Mn, Fe, Co, Ni, Cu, Zn, Cd, B, Al, Si, P, and mixtures thereof, M10 is selected from Mg, Ti, Zr, V, Cr, Mo, W, Mn, Fe, Co, Ni, Cu, Zn, Cd, B, Al, Si, P, and mixtures thereof, and Q is selected from F, N, and mixtures thereof. Most preferably, M8 and M10 are selected from Ti, Zr, V, Cr, Mo, W, Fe, Cu, Zn, Al, P, and mixtures thereof. Preferably, 0≦a≦0.45, 0≦b≦1.0, and 0≦d≦1.0.

[0183] For example, formula 4 is M8 a M9 1-a M10 bNb 12-b O 33-c-d Q d In the formula, The M8 and M9 are different. M8 is selected from Mg, Ti, Zr, V, Nb, Cr, Mo, W, Mn, Fe, Co, Ni, Cu, Zn, Cd, B, Al, Si, P, and mixtures thereof; M9 is Mo or W; M10 is selected from Mg, Ti, Zr, V, Cr, Mo, W, Mn, Fe, Co, Ni, Cu, Zn, Cd, B, Al, Si, P, and mixtures thereof; Q is selected from F, N, and mixtures thereof; 0≦a≦0.45, 0≦b≦1.0, −0.5≦c≦1.65, 0≦d≦1.0, One or more of a, b, c, and d is not equal to 0; If a, b, and d are 0, then c is greater than 0.

[0184] For example, formula 4 is M8 a M9 1-a M10 b Nb 12-b O 33-c-d Q d In the formula, The M8 and M9 are different. M8 is selected from Ti, Zr, V, Cr, Mo, W, Fe, Cu, Zn, Al, P, and mixtures thereof; M9 is Mo or W; M10 is selected from Ti, Zr, V, Cr, Mo, W, Fe, Cu, Zn, Al, P, and mixtures thereof; Q is selected from F, N, and mixtures thereof; 0 <a≦0.45、0≦b≦0.2、-0.25≦c≦1.65、0≦d≦0.8である。

[0185] M8, M10, and Q may also be selected from each of the specific elements used as these dopants in the Examples and Reference Examples.

[0186] Formula 4 may further include Li and / or Na. For example, Li and / or Na may enter the crystal structure when the active electrode material is used in an electrode of a metal-ion battery.

[0187] Nb 2 O 5 The niobium-containing oxide is H-Nb 2 O 5 or N-Nb 2 O 5 , preferably H-Nb 2 O 5 It can be H-Nb 2 O 5 and N-Nb 2 O 5 may be doped with further cations and / or anions. 2 O 5 Further information on the crystal structure of Nb can be found in Griffith et al., J. Am. Chem. Soc. 2016, 138, 28, 8888-8899. 2 O 5 may be obtained from commercial suppliers. EXAMPLES

[0188] Example 1 Electrochemical testing was performed in analytical full coin cells (CR2032 size). The cathode and anode active materials to be tested were combined with N-methylpyrrolidone (NMP), carbon black acting as a conductive additive, poly(vinyl difluoride) (PVDF) binder, and carbon nanotubes (CNTs) and mixed using a laboratory scale centrifugal planetary mixer to form a slurry. The composition of the dried anode was 90 wt% active material, 5 wt% carbon black (Super P), 4 wt% PVdF, and 1 wt% CNTs. The composition of the dried cathode was 91 wt% active material, 4 wt% carbon black (Super P), 4 wt% PVdF, and 1 wt% CNTs. The slurry was doctor blade coated onto an aluminum foil current collector to the desired loading and dried. The electrodes were then run at 80 °C at 2.4-3.0 g cm -3 The material was calendered to a density of 1000 and the target porosity of 31-35% was achieved.

[0189] The anode and cathode electrodes were punched out to the desired size and then individually weighed to achieve the desired N / P ratio. The punched out anode and cathode electrodes were placed in a steel coin cell casing with a separator (Celgard Porous PP / PE) and electrolyte (1.3 M LiPF 6 The cells were then combined with a 1000V EC / DEC containing 1.2% Cr and sealed under pressure. They were then cycled at a low current rate (C / 10) from 1.2 to 3.15 V for two full cycles of lithiation and delithiation. The performance of these cells was then investigated at increasing current densities.

[0190] During the rate test, the cells were cycled asymmetrically by applying a slow charge (C / 5) followed by an increased discharge rate for the discharge characterization test and vice versa for the charge characterization test. DCIR was measured by discharging a full cell to 50% of its state of charge (SOC) at a rate of 0.2C, then pulsing at 5C for 10 seconds. The 0.2C rate was then resumed to 0% SoC. DCIR was determined by the maximum observed voltage difference (dV max ) and the current (l app) was calculated as follows: R=l app / dV max .

[0191] The active anode material used in Example 1 had the formula of Sample I11 below, and had an active material loading of 1.1-1.3 mAhcm -2 , 2.6gcm -3 , and 5.5 to 6.5 mg cm -2 The active cathode material used is NMC622 (LiNi 0.6 Mn 0.2 Co 0.2 O 2 ), active material load 1.2~1.4mAhcm -2 , 2.8gcm -3 , and 7.5 to 8.5 mg cm -2 It is.

[0192] Figure 1 shows the capacity fade as a function of 1C / 1C cycle number. During this test, all cells are cycled with 1C CC charge (constant current non-CV) followed by 1C CC discharge. The graph shows that the N / P=1.1 cell design has slower capacity fade compared to the N / P=0.9 design, indicating that this design is favorable for reducing system degradation and extending cycle life. Cycle life tests were performed at 25°C.

[0193] Figure 2 shows the DCIR increase as a function of cycle number. DCIR was measured by discharging a full cell to 50% of its state of charge (SOC) at a rate of 0.2C, then pulsing at 5C for 10 seconds. The 0.2C rate was then resumed to 0% SoC. DCIR was calculated as the maximum voltage difference (dV max ) and the current (l app ) was calculated as follows: R = l app / dV maxThe measurements were taken every 50 1C / 1C cycles. All measurements were taken at 25°C. The graph shows a clear advantage of an N / P ratio of 1.1. After 200 cycles, the internal resistance of the N / P=0.9 cell shows a 360% increase in DCIR compared to 210% for the N / P=1.1 cell. The lower the increase in DCIR over time, the longer the cell can deliver higher power.

[0194] FIG. 3 shows the baseline capacity fade as a function of cycle number. This "capacity fade" was measured by performing a low C-rate "baseline" cycle every 50 1C / 1C cycles in a cycle life test. The base cycle is a CC charge at C / 5 to 3.15V, CV to C / 40, then CC discharge at C / 5 to 1.2V. The resulting capacity is then plotted on a graph with the corresponding cycle number. All measurements were taken at 25° C. This graph shows that the N / P=1.1 cell design has a slower capacity fade compared to the N / P=0.9 cell design. The slower capacity fade indicates better stability of the anode and cathode materials.

[0195] Figure 4 shows the first cycle formation data. The formation is a CC CV (up to C / 40) charge at C / 5, followed by a CC discharge at C / 5. N / P=1.1 shows higher capacity than N / P=0.9 while maintaining the same first cycle loss. At higher SoC, the N / P=1.1 cell design also shows lower polarization (delta V between charge and discharge), indicating lower internal resistance. Formation was performed at 25°C.

[0196] Figure 5 shows a 10C charge rate test. The test consisted of a C / 5 CC discharge followed by a 10C CC charge. This was done to evaluate the fast charge capability of each system. The graph shows that the N / P=1.1 cell design achieves 73% capacity retention compared to 40% for the N / P=0.9 cell design.

[0197] Figure 6 shows the 10C discharge rate test. This test consisted of a C / 5 CC CV (up to C / 40) charge followed by a 10C CC discharge. This was done to evaluate the discharge rate capability of each system.

[0198] The graph shows that the N / P=1.1 cell design achieves 77% capacity retention compared to 48% for the N / P=0.9 cell design.

[0199] Example 2 Electrochemical testing was performed in analytical full coin cells (CR2032 size). The cathode and anode active materials to be tested were combined with N-methylpyrrolidone (NMP), carbon black to act as a conductive additive, and poly(vinyl difluoride) (PVDF) binder and mixed using a laboratory scale centrifugal planetary mixer to form a slurry. The composition of the dry anode was 92 wt% active material, 5 wt% carbon black (Super P), and 3 wt% PVdF. The composition of the dry cathode was 92 wt% active material, 5 wt% carbon black (Super P), and 3 wt% PVdF. The slurry was doctor blade coated onto an aluminum foil current collector to the desired loading and allowed to dry. The electrodes were then run at 80 °C at 2.4-3.0 g cm -3 The material was calendered to a density of 1000 and the target porosity of 31-35% was achieved.

[0200] The anode and cathode electrodes were punched out to the desired size and then individually weighed to achieve the desired N / P ratio. The punched out anode and cathode electrodes were placed in a steel coin cell casing with a separator (Celgard Porous PP / PE) and electrolyte (1.3 M LiPF 6The cells were then combined with an EC / EMC containing EDTA and sealed under pressure. They were then cycled at a low current rate (C / 5) for two full cycles of charge and discharge from 1.0 to 3.05 V. The performance of these cells was then examined by increasing the current density. During the rate test, the cells were cycled asymmetrically by increasing the discharge rate for the discharge characteristic test and vice versa for the charge characteristic test after a slow charge (C / 5).

[0201] The active anode material used in Example 2 had approximately the formula of Sample E6 below, with an active material loading of 6.5-7.5 mg cm -2 The active cathode material used is NCA (LiNi 0.x Co 0.y Al 1-0.x-0.y O 2 ), active material load 6.5~9.0mgcm -2 It is.

[0202] FIG. 7 shows the first cycle formation data. The formation is a CC CV (up to C / 40) charge at C / 5, followed by a CC discharge at C / 5. N / P=0.9 shows higher first cycle losses than N / P=1.1. At higher SoC, the N / P=1.1 cell design also shows lower polarization (delta V between charge and discharge), indicating lower internal resistance. Formation was performed at 25° C.

[0203] Figure 8 shows a 10C charge rate test. The test consisted of a C / 5 CC discharge followed by a 10C CC charge. This was done to evaluate the fast charging capabilities of each system. The graph shows that the N / P=1.1 cell design achieves 88% capacity retention compared to 76% for the N / P=0.9 cell design.

[0204] Figure 9 shows a 10C discharge rate test. This test consisted of a C / 5 CC CV (up to C / 40) charge followed by a 10C CC discharge. This was done to evaluate the discharge rate capability of each system. The graph shows that the N / P=1.1 cell design achieves 86% capacity retention compared to 85% for the N / P=0.9 cell design.

[0205] Example 3 Electrochemical testing was performed in analytical full coin cells (CR2032 size). The cathode and anode active materials to be tested were combined with N-methylpyrrolidone (NMP), carbon black to act as a conductive additive, and poly(vinyl difluoride) (PVDF) binder and mixed using a laboratory scale centrifugal planetary mixer to form a slurry. The composition of the dry anode was 92 wt% active material, 5 wt% carbon black (Super P), and 3 wt% PVdF. The composition of the dry cathode was 92 wt% active material, 5 wt% carbon black (Super P), and 3 wt% PVdF. The slurry was doctor blade coated onto an aluminum foil current collector to the desired loading and allowed to dry. The electrodes were then run at 80 °C at 2.4-3.0 g cm -3 The material was calendered to a density of 1000 and the target porosity of 31-35% was achieved.

[0206] The anode and cathode electrodes were punched out to the desired size and then individually weighed to achieve the desired N / P ratio. The punched out anode and cathode electrodes were placed in a steel coin cell casing with a separator (Celgard Porous PP / PE) and electrolyte (1.3 M LiPF 6 The cells were combined with an EC / DEC containing 1.0% EDTA and sealed under pressure. They were then cycled at a low current rate (C / 5) for two full cycles of charge and discharge from 1.0 to 3.05 V. The performance of these cells was then examined by increasing the current density. During the rate test, the cells were cycled asymmetrically by increasing the discharge rate for the discharge characteristic test and vice versa for the charge characteristic test after a slow charge (C / 5).

[0207] The active anode material used in Example 3 had the formula of Sample G16 below, and an active material loading of 6.5-7.5 mg cm -2 The active cathode material used is NCA (LiNi 0.x Co 0.y Al 1-0.x-0.y O 2), active material load 6.5~9.0mgcm -2 It is.

[0208] FIG. 10 shows the first cycle formation data. The formation is a CC CV (up to C / 40) charge at C / 5, followed by a CC discharge at C / 5. N / P=0.9 shows higher first cycle losses than N / P=1.1. At higher SoC, the N / P=1.1 cell design also shows lower polarization (delta V between charge and discharge), indicating lower internal resistance. Formation was performed at 25° C.

[0209] Figure 11 shows a 10C charge rate test. The test consisted of a C / 5 CC discharge followed by a 10C CC charge. This was done to evaluate the fast charge capability of each system. The graph shows that the N / P=1.1 cell design achieves 76% capacity retention compared to 57% for the N / P=0.9 cell design.

[0210] Figure 12 shows a 10C discharge rate test. This test consisted of a C / 5 CC CV (up to C / 40) charge followed by a 10C CC discharge. This was done to evaluate the discharge rate capability of each system. The graph shows that the N / P=1.1 cell design achieves 74% capacity retention compared to 65% for the N / P=0.9 cell design.

[0211] Example 4 Electrochemical testing was performed in analytical full coin cells (CR2032 size). The cathode and anode active materials to be tested were combined with N-methylpyrrolidone (NMP), carbon black to act as a conductive additive, and poly(vinyl difluoride) (PVDF) binder and mixed using a laboratory scale centrifugal planetary mixer to form a slurry. The composition of the dry anode was 92 wt% active material, 5 wt% carbon black (Super P), and 3 wt% PVdF. The composition of the dry cathode was 92 wt% active material, 5 wt% carbon black (Super P), and 3 wt% PVdF. The slurry was doctor blade coated onto an aluminum foil current collector to the desired loading and allowed to dry. The electrodes were then run at 80 °C at 2.7-3.0 g cm -3 The material was calendered to a density of 1000 and the target porosity of 27-33% was achieved.

[0212] The anode and cathode electrodes were punched out to the desired size and then individually weighed to achieve the desired N / P ratio. The punched out anode and cathode electrodes were placed in a steel coin cell casing with a separator (Celgard Porous PP / PE) and electrolyte (1M LiPF 6 The cells were then combined with an EC / EMC containing EDTA and sealed under pressure. They were then cycled at a low current rate (C / 10) for two full cycles of charge and discharge from 1.0 to 3.05 V. The performance of these cells was then examined by increasing the current density. During the rate test, the cells were cycled asymmetrically by increasing the discharge rate for the discharge characteristic test and vice versa for the charge characteristic test after a slow charge (C / 5).

[0213] The active anode material used in Example 4 had the formula of Sample E8 below, and an active material loading of 6.5-7.5 mg cm -2 The active cathode material used is NCA (LiNi 0.x Co 0.y Al 1-0.x-0.y O 2 ), active material loading 6.5~8.4mgcm -2 It is.

[0214] FIG. 13 shows the first cycle formation data as a function of voltage versus normalized capacity. The formation is a CC charge at C / 10 followed by a CC discharge at C / 10. At higher SoC (>50%), the N / P=1.1 cell design exhibits lower polarization (delta V between charge and discharge), indicating lower internal resistance. Formation was performed at 25° C.

[0215] Figure 14 shows a 10C charge rate test. The test consisted of a C / 5 CC discharge followed by a 10C CC charge. This was done to evaluate the fast charge capability of each system. The graph shows that the N / P=1.1 cell design achieves 89% capacity retention compared to 82% for the N / P=0.9 cell design.

[0216] Figure 15 shows a 10C discharge rate test. The test consisted of a C / 5 CC CV (up to C / 40) charge followed by a 10C CC discharge. This was done to evaluate the discharge rate capability of each system. The graph shows that the N / P=1.1 cell design achieves 86% capacity retention compared to 85% for the N / P=0.9 cell design.

[0217] Reference example The following examples provide methods for the synthesis of niobium-containing oxides as active anode materials for use in accordance with the present invention. The examples demonstrate the electrochemical performance of these materials when tested in half cells. It is expected that the beneficial properties observed will also be present when these materials are utilized in full cells with appropriate N / P ratios in accordance with the present invention.

[0218] Reference examples related to formula 1 Mixed niobium oxides were synthesized by a solid-state route. In the first step, the precursor material (Nb 2 O 5 , GeO 2 , ZnO, TiO 2 , Cr 2 O 3 , Al 2 O 3, Fe 2 O 3 , ZrO 2 , and CuO) with a D of less than 20 μm 50 The materials were mixed in stoichiometric ratios (50 g total) and impact milled to a uniform powder mixture at 20,000 rpm. The resulting powder was heated in an alumina crucible in a muffle furnace at 1000 rpm for 10 min at 37° C. in air. 1 = 600-1350 °C for 0.5-24 hours to obtain the desired Wadsley-Roth phase. Selected samples (E9-E11) were removed from the furnace after heat treatment, impact milled at 20,000 rpm, and then the heat treatment was repeated under similar conditions. Specifically, the precursor mixture was heated at a ramp rate of 5° / min to a temperature below 800 °C, then at a ramp rate of 1° / min to the maximum temperature for a holding time. In some cases, further heat treatment steps were also performed using N 2 Under the atmosphere, T 2 = 600-1350 °C for 0.5-12 h. Further milling / mixing of the precursors to include anions (PVDF in a 1:10 mass ratio with respect to the parent material for F, and C if N is required). 3 H 6 N 6 may be used in a mass ratio of 1:3), followed by N 2 Or in air, in one or two steps, T 2a / T 2b Heat treatment was performed at 300 to 1200°C for 0.5 to 12 hours.

[0219] If necessary, a final deagglomeration step by impact milling or jet milling was used to adjust the particle size distribution to the desired size. Specifically, the material was deagglomerated by impact milling at 20,000 RPM for 10 seconds. The particle size distribution was obtained on a Horiba dry powder laser diffraction particle analyzer. The air pressure was maintained at 0.3 MPa. The results are shown in Table E1. [Table 1]

[0220] Material characterization The phase purity of the samples was analyzed using a Rigaku Miniflex powder X-ray diffractometer at a scan rate of 1° / min in the 2θ range (10–70°).

[0221] Figure E1 shows the measured XRD diffraction patterns for samples E1-E4, and Figure E2 for samples E5-E12. The diffraction patterns have peaks at the same positions (with some shifts due to crystallographic modifications up to about 0.2°) and are consistent with the crystallographic database entry JCPDS 28-1478. Certain samples have the same Wadsley-Roth block structure (Zn 2 Nb 34 O 87 ) is found to be a phase mixture of monoclinic (JCPDS 28-1478, reference a) and orthorhombic (PDF card, 04-021-7859, reference b) crystal structures and refined to this mixture. There is no amorphous background noise and the peaks are sharp and intense. This is because all samples are crystalline, with crystallite sizes according to the Scherrer formula of 45-55 nm and a crystal structure of Zn. 2 Nb 34 O 87 This confirms the presence of the Wadsley-Roth crystal structure. [Table 2]

[0222] Electrochemical characterization Electrochemical testing was performed in analytical half coin cells (CR2032 size). In the half coin test, active materials are tested against a Li metal electrode to evaluate their fundamental performance. In the following reference examples, the test active material compositions were combined with N-methylpyrrolidone (NMP), carbon black (Super P) acting as a conductive additive, and poly(vinyl difluoride) (PVDF) binder and mixed using a laboratory scale centrifugal planetary mixer to form slurries. The non-NMP composition of these slurries was 92 wt% active material, 3 wt% conductive additive, and 5 wt% binder. The slurries were doctor blade coated onto Al foil current collectors at the desired loading of 69-75 gm. -2 These electrodes were then coated with 2.6 to 2.9 gcm -3 The electrodes were then punched to the desired size and packed into a steel coin cell casing containing a separator (Celgard porous PP / PE), Li metal, and electrolyte (1.3 M LiPF 6 The cells were then combined with an EC / DEC containing 1.1-3.0 V and sealed under pressure. They were then cycled at 23° C. at a low current rate (C / 10) for two full cycles of lithiation and delithiation from 1.1 to 3.0 V. The performance of these cells was then examined at increasing current densities. During these tests, the cells were asymmetrically cycled at 23° C. with slow lithiation (C / 5) followed by increasing delithiation rates (e.g., 1 C, 5 C, 10 C) to obtain capacity retention and nominal voltage at 5 C. The nominal voltage vs Li / Li+ was calculated from the integral of the V / Q curve divided by the total capacity at 5 C during delithiation. No constant voltage step was used. Data are averaged from five cells prepared from the same electrode composition, with errors shown from standard deviation. Thus, these data represent a robust test showing the improvement achieved by the material according to the invention compared to conventional materials. These data are shown in Tables E4 and E5.

[0223] The cell resistance is calculated from the direct current internal resistance (DCIR) of a half coin cell. A typical measurement is to lithiate the cell to 100% state of charge (SOC), then delithiate it at a rate of C / 10 to 50% SOC, then rest for 0.5 hours, then apply a 5C delithiation pulse for 10 seconds, then rest for another 0.5 hours. DCIR is then calculated from V=IR using the voltage just before the peak from the pulse and the maximum voltage measured during the pulse.

[0224] The electrical resistivity of the electrode compositions was evaluated individually by a four-point probe method using an Ossila instrument (T2001A3-UK) at 23°C. Slurries were formed (the active material compositions to be tested were combined with N-methylpyrrolidone (NMP), carbon black acting as a conductive additive, and poly(vinyl difluoride) (PVDF) binder and mixed using a laboratory scale centrifugal planetary mixer to form slurries. The non-NMP composition of these slurries was 80 wt% active material, 10 wt% conductive additive, and 10 wt% binder). The slurries were then coated onto dielectric Mylar films at a loading of 1 mg / cm. Electrode-sized disks were then punched out and the resistance of the coated films was measured using a four-point probe. The sheet resistance (Ω / square) results are summarized in Table E3. Errors are based on the standard deviation of triplicate measurements.

[0225] Homogeneous, smooth, visible defect and agglomerate free coatings on both Cu and Al current collector foils may also be prepared for these samples in a centrifugal planetary mixer as described above with compositions up to 94 wt% active material, 4 wt% conductive additive, and 2 wt% binder. These can be prepared with both PVDF (i.e., NMP-based) and CMC:SBR-based (i.e., aqueous) binder systems. These coatings are calendered at 80°C for PVDF and 50°C for CMC:SBR and are deposited at 1.0-5.0 mAhcm. -2 Porosity of 35-40% can be achieved at loadings of 1000 μm, which is important for achieving high active material content and demonstrating the viability of these materials in both high energy and high power applications. [Table 3] [Table 4] [Table 5] [Table 6]

[0226] Consideration Mixed niobium oxide sample E1 * Ge 4+ Zn substituted with 2+ The cation substitution approach in sample E3 focused on the cation. Samples E5-E8 show that Zn 2+ The cation is Cr 3+ Cation substituted, Nb 5+ The cation is Ti 4+ The sample E10 is substituted with Nb 5+ Fe 3+ Sample E11 is substituted with Zn 2+ Al 3+ Sample E12 is replaced by Cu. 2 Nb 34 O 87 Based on Cu 2+ The cation is Cr 3+ Cation substituted, Nb 5+ The cation is Ti 4+ The increase in valence is due to partial oxygen excess (i.e., c<0) and / or Nb 5+ The reduction in vacancies can be compensated for by the formation of oxygen vacancies (i.e., c>0). These modifications are due to a combination of (a) altered ionic radius, (b) altered valence, and (c) altered voltage in sample E1. *The modified ionic radius is expected to provide benefits over the base crystal structure of the modified sample. The altered ionic radius may provide beneficial changes in electrochemical performance due to altered unit cell size and local distortion of the crystal structure, altering the available lithiation sites or pathways, potentially improving coulombic efficiency, capacity, high rate performance, and lifetime. The altered valence provides intermediate energy levels available for charge carriers, thus significantly improving the electrical conductivity of the material. These effects are evident in the observed changes in resistivity of modified samples in Table E3, Sample E1. * This is shown by the reduction in specific capacity vs. C and by the improvements in coulombic efficiency, delithiation voltage at 5C, and capacity retention at 1C, 5C, and 10C observed in Tables E4-E6. These are important results that demonstrate the utility of the modified mixed niobium oxides according to the present invention for use in high power Li-ion cells designed for high rate charge / discharge.

[0227] Table E2 shows the changes in unit cell parameters observed after cation exchange, i.e., due to changes in the ionic radius and electronic structure of these materials.

[0228] It is anticipated that similar benefits will be observed with the cation exchange approach described herein for this material for use in Li-ion cells.

[0229] Mixed niobium oxide sample E1 * has been modified through the introduction of induced oxygen vacancies by heat treatment in an inert or reducing atmosphere to give sample E2. By treating the "base" oxide at high temperature in an inert or reducing atmosphere, it can be partially reduced and remain so even after returning to room temperature and exposure to an air atmosphere. This is accompanied by a clear color change, e.g. sample E2 is grey / black, whereas sample E1 is black. *In contrast, the color of the sample E1 is white at 1000 MHz and the color of the sample B1 is white at 1000 MHz. This color change indicates a significant change in the electronic structure of the material that allows it to interact with visible light of different energies (i.e., wavelengths) due to a decrease in the band gap. This is reflected in sample E2, which showed an improvement in the delithiation voltage at a rate of 5C, which corresponds to a decrease in the polarization level of the cell.

[0230] The induced oxygen vacancies result in defects in the crystal structure, e.g., oxygen anions are removed, which in turn reduces the overall redox state of the cations. This provides additional energy states that greatly improve the electrical conductivity of the material, and changes the band gap energy as indicated by the color change. This is consistent with the increase in resistivity of sample E1, as observed in Table E3 for sample E2. * If the induced oxygen vacancies are present in excess of 5 atomic % (i.e., c>4.35), the stability of the crystal structure may be reduced.

[0231] Mixed niobium oxide sample E1 * is an anion substitution (F - By O 2- (substitution of ) to give sample E4. An improvement in the specific capacity was observed (Tables E4 and E5).

[0232] It is expected that similar benefits would be observed in any of the mixed niobium oxides described herein using any combination of M1, M2, M3, Q, a, b, c, and d for use in Li-ion cells, within the limitations described herein.

[0233] Reference examples related to formula 2 Mixed niobium oxides were synthesized by a solid-state route. In the first step, the precursor material (Nb 2 O 5 , Ga 2 O 3 , ZnO, ZrO 2 , Cr 2 O 3 , CEO 2 , and Al 2 O 3) with a D of less than 20 μm 50 The materials were mixed in stoichiometric ratios (50 g total) and impact milled to a uniform powder mixture at 20,000 rpm. The resulting powder was heated in an alumina crucible in a muffle furnace at 1000 rpm for 10 min at 37° C. in air. 1 = 600-1350 °C for 0.5-24 hours to obtain the desired Wadsley-Roth phase. Specifically, the precursor mixture was heated at a ramp rate of 5° / min to a temperature below 800 °C, then at a ramp rate of 1° / min to the maximum temperature for a holding period. In some cases, further heat treatment steps were also performed using N 2 Under the atmosphere, T 2 = 600-1350 °C for 0.5-12 h. Further milling / mixing of the precursors to include anions (PVDF in a 1:10 mass ratio with respect to the parent material for F, and C if N is required). 3 H 6 N 6 may be used in a mass ratio of 1:3), followed by N 2 Or in air, in one or two steps, T 2a / T 2b Heat treatment was performed at 300 to 1300°C for 0.5 to 24 hours.

[0234] If necessary, a final deagglomeration step by impact milling or jet milling was used to adjust the particle size distribution to the desired size. Specifically, the material was deagglomerated by impact milling at 20,000 RPM for 10 seconds. The particle size distribution was obtained with a Horiba dry powder laser diffraction particle analyzer. The air pressure was maintained at 0.3 MPa. The results are shown in Table F1. [Table 7]

[0235] Material characterization The phase purity of the samples was analyzed using a Rigaku Miniflex powder X-ray diffractometer at a scan rate of 1° / min in the 2θ range (10–70°).

[0236] Figure F1 shows the measured XRD diffraction patterns for samples F1-F4, and Figure F2 shows the patterns for samples F5-F9. The diffraction patterns have peaks at the same positions (with some shifts due to crystallographic modifications up to about 0.2°) and are consistent with the crystallographic database entry JCPDS 22-009. There is no amorphous background noise and the peaks are sharp and intense. This indicates that all samples are crystalline, with crystallite sizes according to the Scherrer formula of 40-60 nm and a crystal structure of AlNb 11 O 29 This confirms the presence of the Wadsley-Roth crystal structure. [Table 8]

[0237] Electrochemical characterization Electrochemical testing was performed in analytical half coin cells (CR2032 size). In the half coin test, active materials are tested against a Li metal electrode to evaluate their fundamental performance. In the following reference examples, the test active material compositions were combined with N-methylpyrrolidone (NMP), carbon black (Super P) acting as a conductive additive, and poly(vinyl difluoride) (PVDF) binder and mixed using a laboratory scale centrifugal planetary mixer to form slurries. The non-NMP composition of these slurries was 92 wt% active material, 3 wt% conductive additive, and 5 wt% binder. The slurries were doctor blade coated onto Al foil current collectors at the desired loading of 69-75 gm. -2 These electrodes were then coated with 2.6 to 2.9 gcm -3 The electrodes were then punched to the desired size and packed into a steel coin cell casing containing a separator (Celgard porous PP / PE), Li metal, and electrolyte (1.3 M LiPF 6The cells were then combined with a 100% ethylenediaminetetraacetate (EC / DEC) containing 100% ethylenediaminetetraacetate (EDTA) and sealed under pressure. They were then cycled at 23°C at low current rates (C / 10) from 1.1 to 3.0 V for two full cycles of lithiation and delithiation. The performance of these cells was then examined at increasing current densities. During these tests, the cells were asymmetrically cycled at 23°C with slow lithiation (C / 5) followed by increasing delithiation rates (e.g., 1C, 5C, 10C) to obtain capacity retention and nominal voltage at 5C. The nominal voltage vs Li / Li+ was calculated from the integral of the V / Q curve divided by the total capacity at C / 10 and 5C during delithiation. No constant voltage step was used.

[0238] The cell resistance is calculated from the direct current internal resistance (DCIR) of a half coin cell. In a typical measurement, the cell is lithiated to 100% SOC, then delithiated at a rate of C / 10 to 50% SOC, then rested for 0.5 hours, followed by a 5C delithiation pulse for 10 seconds, then rested for another 0.5 hours. DCIR is then calculated from V=IR using the voltage just before the peak and the maximum voltage measured during the pulse.

[0239] Data are averaged from five cells prepared from the same electrode composition, with errors shown from standard deviations, and therefore these data represent a robust test showing the improvements achieved by the materials according to the invention compared to conventional materials.

[0240] Homogeneous, smooth, visible defect and agglomerate free coatings on both Cu and Al current collector foils may also be prepared for these samples in a centrifugal planetary mixer as described above with compositions up to 94 wt% active material, 4 wt% conductive additive, and 2 wt% binder. These can be prepared with both PVDF (i.e., NMP-based) and CMC:SBR-based (i.e., aqueous) binder systems. These coatings are calendered at 80°C for PVDF and 50°C for CMC:SBR and are deposited at 1.0-5.0 mAhcm. -2Porosity of 35-40% can be achieved at loadings of 1000 μm, which is important for achieving high active material content and demonstrating the viability of these materials in both high energy and high power applications. [Table 9] [Table 10]

[0241] Consideration Mixed niobium oxide sample F1 * Ga 3+ Al substituted with 3+ The cation-focused sample F2 has been modified by a cation-substitution approach. Samples F5 to F9 are Al 3+ with additional cations (Zn 2+ , Zr 4+ , Cr 3+ , and Ce 4+ ) which is due to the combination of the changed ionic radius and the changed voltage. * The cation exchange is expected to provide benefits over the base crystal structure of Ga. Table F2 shows the changes in unit cell parameters observed after cation exchange, i.e., due to changes in the ionic radius and electronic structure of these materials. The altered ionic radius may provide beneficial changes in electrochemical performance due to changes in unit cell size and local distortion of the crystal structure, altering the available lithiation sites or lithiation pathways, potentially improving capacity, high rate performance, and lifetime. For example, the 6-coordinate Ga 3+ The ionic radius of the cation is 0.62 Å, whereas the 6-coordinate Al 3+ The ionic radius of the cation is 0.54 Å. These effects are shown in Table F3 for sample F1. *This is shown by the improved lower delithiation voltages at C / 10 and 5C for the modified samples compared to Table F4. Additionally, Table F4 shows improved capacity retention at rates above 5C, with even greater improvement at the higher 10C rates, results that are important in demonstrating the utility of the mixed niobium oxide modified according to the present invention for use in high power Li-ion cells designed for fast charge / discharge. Similar benefits are expected to be observed with the cation exchange approach described herein for this material for use in Li-ion cells.

[0242] The mixed niobium oxide was treated with F - The anion was introduced to give sample F4. Similar to the cation exchange, this exchange was carried out by introducing an anion. 2- It may occur at an anion site, in which case the increased valence may increase the electronic conductivity of the material. It may also occur at interstitial sites in the crystal structure. In either case, this may result in different unit cell sizes and associated crystallographic distortions due to the different ionic radii and valences of the anions, providing similar potential benefits as cation exchange. It is expected that similar benefits will be observed using anions of different electronegativity and valence with any of the MNO structures described herein for use in Li-ion cells.

[0243] The mixed niobium oxides are modified by induced oxygen deficiencies through heat treatment in an inert or reducing atmosphere to give sample F3. By treating these materials at high temperatures in an inert or reducing atmosphere, they can be partially reduced and maintained after returning to room temperature and exposure to an air atmosphere. This is shown in Table F4, particularly in sample F1 at 5C and above. * This is reflected in sample F3, which has a further improved capacity retention compared to sample F1 and a further improved cell resistance.

[0244] Induced oxygen vacancies are defects in the crystal structure that, for example, remove oxygen anions, which then reduce the overall redox state of the cations. This provides additional energy states that significantly improve the electrical conductivity of the material, changing the band gap energy. If induced oxygen vacancies are present in excess of 5 atomic % (i.e., c>1.45), the stability of the crystal structure may be reduced.

[0245] It is expected that similar advantages will be observed in any of the MNO structures described herein using any combination of M4, M5, Q, a, b, c, and d for use in Li-ion cells, within the limitations of the present description.

[0246] Reference examples related to formula 3 The phosphorus-based niobium oxide material was synthesized by a solid-state route. In the first step, the precursor material (Nb 2 O 5 , N.H. 4 H 2 PO 4 , TiO 2 , MoO 3 , H 3 BO 3 , Al 2 O 3 , ZrO 2 , GeO 2 , Ga 2 O 3 , Cr 2 O 3 ) were mixed in a stoichiometric ratio (total of 350 g) and ball milled at 550 rpm with a ball to powder ratio of 10:1 for 3 hours. The resulting powder was then heated in an alumina crucible in a muffle furnace at 37° C. in air at 20° C. for 3 hours. 1a = 250 to 600 °C for 1 to 12 hours, followed by T 1b = 800-1350 °C for 4-24 hours to obtain the desired Wadsley-Roth phase. In some cases, further heat treatment steps were also performed using N 2 Under the atmosphere, T 2= 800-1350 °C for 1-12 hours, resulting in induced oxygen vacancies in the base crystal structure. Further milling / mixing of the precursors to include anions (for N, NH 4 HCO 3 For F, PVDF was used in a mass ratio of 1:3, and for F, PVDF was used in a mass ratio of 1:10. 2 For atmosphere, F is air atmosphere, and T is 2 Heat treatment was performed at 400 to 1200°C for 1 to 24 hours.

[0247] If necessary, a final deagglomeration step by impact milling or jet milling was used to adjust the desired particle size distribution. Specifically, the material was deagglomerated by impact milling at 20,000 RPM for 10 seconds. [Table 11-1] [Table 11-2]

[0248] Material characterization The phase purity of the samples was analyzed using a Rigaku Miniflex powder X-ray diffractometer in the 2θ range (20–70°) at a scan rate of 1° / min.

[0249] Figure G1 shows the XRD diffraction patterns measured for samples G1 to G9. Figure G2 shows the XRD diffraction patterns measured for samples G10 to G17. The diffraction patterns have peaks at the same positions (including some shifts due to doping up to about 0.2°), and PNb 9 O 25 The peaks are sharp and intense, with no amorphous background noise. This indicates that all samples are phase pure and crystalline, with crystallite sizes between 30 and 60 nm according to the Scherrer formula, and a crystal structure of PNb 9 O 25This confirms the presence of the Wadsley-Roth crystal structure. [Table 12]

[0250] Thermogravimetric analysis (TGA) was performed on some samples in an air atmosphere using a Perkin Elmer Pyris 1 system. Samples were heated from 30°C to 900°C at 5°C / min and held at 900°C for 30 minutes with 20 mL / min air flow. TGA was performed on samples G2 and G7 to quantify the mass change upon oxidation. The measured mass increase was assumed to correspond to the degree of induced oxygen vacancies present. [Table 13]

[0251] 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 G1.

[0252] Electrochemical characterization Electrochemical testing was performed in analytical half coin cells (CR2032 size). In the half coin test, active materials are tested against a Li metal electrode to evaluate their fundamental performance. In the following reference examples, the test active material compositions were combined with N-methylpyrrolidone (NMP), carbon black, which acts as a conductive additive, and poly(vinyl difluoride) (PVDF) binder, and mixed using a laboratory scale centrifugal planetary mixer to form slurries. The non-NMP composition of these slurries was 90 wt% active material, 6 wt% conductive additive, and 4 wt% binder. The slurries were doctor blade coated onto Al foil current collectors at the desired loading of 70 gm -2 These electrodes were then coated with 2.6–3.2 gcm at 80°C and dried. -3The electrodes were then punched to the desired size and packed into a steel coin cell casing containing a separator (Celgard porous PP / PE), Li metal, and electrolyte (1.3 M LiPF 6 The cells were then combined with an EC / DEC containing LiCl and sealed under pressure. They were then cycled at low current rates (C / 10) at 23°C for two full cycles of lithiation and delithiation at 1.0-2.5 V for samples G1-G9 and 1.0-3.0 V for samples G10-G17. The performance of these cells was then examined at increasing current densities. During the rate tests, slow charging (lithiation, C / 5) was performed, followed by increasing discharge rates (delithiation, e.g., 1C, then 2C, then 5C, then 10C) for the discharge characteristic tests, and the cells were cycled asymmetrically at 23°C (e.g., to measure capacity retention). Nominal voltage vs Li / Li + is calculated from the integral of the V / Q curve during delithiation divided by the total capacity at 5 C. Samples G10-G17 were evaluated at least in triplicate and errors are shown as standard deviations.

[0253] The electrical resistivity of the electrode compositions was evaluated by a four-point probe method using an Ossila instrument. For all samples, the electrode compositions were applied to an insulating Mylar sheet at a mass loading of 70 g cm -2 and calendered to a porosity of 35-40%. The sheet resistance was then measured in Ω / square on a 15 mm diameter disk at a constant temperature of 23 °C.

[0254] Also, homogeneous, smooth, visible defect and agglomerate free coatings on both Cu and Al current collector foils were prepared for selected samples in a centrifugal planetary mixer as described above with compositions up to 94 wt% active material, 4 wt% conductive additive and 2 wt% binder. They were prepared with both PVDF and CMC:SBR based binder systems. The coatings were calendered at 80°C for PVDF and 50°C for CMC:SBR and delivered at 1.0-3.5 mAhcm. -2This is an important demonstration of the viability of these materials for electrodes of commercial interest in both high-energy and high-power applications. [Table 14] [Table 15] [Table 16]

[0255] Reference Example 3A - Sample G1 * and G3 Comparison sample G1 * In sample G3, the overall valence is maintained and P 5+ It is modified via cation substitution with a cation (i.e., isovalent M6 substitution with a>0). Since the valence is maintained, PNb 9 O 25 The effect on the active material is due to changes in the unit cell size and local distortions of the crystal structure as a result of the difference in ionic radii of the cations used. For example, 4-coordinate P 5+ The ionic radius of the cation is 0.17 Å, whereas the ionic radius of the tetracoordinated Ti 4+ The ionic radius of the cation is 0.42 Å. This may result in improved electrochemical performance by modifying the availability of Li-ion sites with different cavity sizes (in this case, perhaps especially type VI cavities) and the resulting electrochemical properties, e.g., improved specific capacity or improved Coulombic efficiency by suppressing the energy barrier for reversible lithiation. This may also result in improved electrical conductivity due to changes in crystal properties, and reduced electrochemical impedance / polarization due to improved diffusion of Li-ions.

[0256] P 5+ The cation can be replaced with an alternative electrochemically active cation, e.g., Ti 4+ Or Mo 6+ Also, for example, nominal voltage vs Li / Li+ These can help tune the redox properties of the materials by lowering the charge transport properties and increasing the energy density of the full cell, or by improving the capacity and coulombic efficiency through more efficient and reversible redox processes.

[0257] Table G2 shows sample G1 * Table G3 shows the changes that occurred in the unit cell parameters between G1 and G2. In particular, the a and b parameters changed by an increase of 0.0075 Å, while the c parameter showed a slight decrease of 0.0030 Å. This demonstrates that isovalent substitution in materials with large ionic radii can induce lattice expansion in the a and b directions. This extends to the slight improvement in electrical resistivity shown in Table G4, which shows that the c parameter showed a slight decrease of 0.0030 Å compared to the c parameter shown in Table G5. * from 18 Ω / sq for sample G3. The electrochemical performance shows significant improvements in Tables G5 and G6, with improved specific capacity, improved second cycle coulombic efficiency, and reduced polarization at high voltage (expressed as nominal voltage at 5C). Additionally, specific capacity retention is improved at high rates of 10C, and possibly even beyond this, at rates of 20C or greater, or 50C or greater, or 100C or greater.

[0258] Similar benefits are expected to be observed with the M6 ​​dopants described herein for use in Li-ion cells.

[0259] Reference Example 3B - Sample G1 * , G4, and G5 Comparison sample G1 * In samples G4 and G5, Nb 5+ The samples are modified through cation substitution (i.e., isovalent M7 substitution with b>0). As a result of the change in unit cell size, electrical, and electrochemical properties, the same advantages as those in Reference Example 3A can be observed. Specifically, Samples G4 and G5 are the same as Sample G1 in Table G4. *and in Table G6, improvements in specific capacity retention at rates as high as 10C, and possibly even beyond this at rates of 20C or greater, or 50C or greater, or 100C or greater.

[0260] Similar benefits are expected to be observed with the M7 dopants described herein for use in Li-ion cells.

[0261] Reference Example 3C - Sample G1 * , G6, G9, and G11 to G17 Comparison sample G1 * is modified in samples G6, G9, and G11-G17 via cation substitution without maintaining the overall valence. For example, lower valence cations are used in samples G6 and G9, and others in the case of sample G6. The advantage of changing the ionic radius by substitution is maintained, as described in Reference Examples 3A and 3B. For samples G6 and G9, the lower valence leads to a change in the crystal structure and a change in the electronic structure. When substitution occurs at the same cation site, e.g., P 5+ Al 3+ When directly substituted with , the O content of the material is proportionally reduced to maintain a charge-balanced structure (i.e., the base PNb 9 O 25 The oxygen vacancies in the structure create defects and additional charge carriers (i.e., electron holes) in the structure, enhancing electrical conductivity. This can also induce crystal distortions due to changes in the coordination of the O anions with the surrounding P / Nb cations, further improving electrical and electrochemical performance in a similar way to the ionic radius changes described.

[0262] This is observed in Table G2, where the unit cell parameters show a decrease in the a and b parameters, as well as a decrease in the c parameter, generally indicating minor crystal structure contraction. Electrical resistivity measurements show an improvement in Table G4, where a large decrease in sheet resistance is observed relative to sample G1. Electrochemical measurements further show advantages in specific capacity, second cycle coulombic efficiency, polarization, and high rate capacity retention for both samples G6 and G9 in Tables G5 and G6.

[0263] Samples G11 to G17 are 5+ by M6 or Nb 5+ Each of the samples G11 to G17 shows a further substitution by M7 of the compound G1 that does not maintain the overall valence. * Compared with (Table G6), the capacity retention rate at high rates was significantly improved.

[0264] P for use in Li-ion cells 5+ or Nb 5+ It is expected that similar benefits will be observed with low or high valence cation or anion exchange relative to .

[0265] Reference example 3D-Sample G1 * , G2, G6, and G7 Comparison sample G1 * Samples G2 and G6 have been modified through the introduction of induced oxygen vacancy defects (see oxygen defects) by heat treatment in an inert or reducing atmosphere to give samples G2 and G7. By treating these materials at high temperatures in an inert or reducing atmosphere, they are partially reduced, which can be maintained even after returning to room temperature and exposure to an air atmosphere. This is accompanied by a clear color change, e.g. sample G2 is light blue, whereas sample G1 is light blue. * In contrast, the material is white in the dark. This color change indicates a significant change in the electronic structure of the material that allows it to interact with visible light of different energies (i.e., wavelengths) due to a reduction in the band gap.

[0266] Induced oxygen vacancies are specifically defects in the crystal structure where an oxygen anion has been removed. This results in an excess of electrons that greatly improve the electrical conductivity of the material, and changes the band gap energy as indicated by the color change. If induced oxygen vacancies are present in excess of 5 atomic % (i.e., c>1.25), the crystal structure collapses due to reduced stability. These induced oxygen vacancies can be present in addition to the oxygen vacancies caused by the use of subvalent cation exchange, as shown in sample G7. Evidence of oxygen vacancies is provided here by TGA analysis in air showing an increase in mass after increasing temperature. This is due to the fact that oxidation of sample G1 * and G6, again resulting in a structure similar to that of G6, which is hypothesized to correspond to the degree of oxygen vacancies present. Many other techniques can also be used to quantify oxygen vacancies, as discussed above.

[0267] Table G2 shows the change in unit cell parameters that occurs after inducing oxygen vacancies in samples G2 and G7. Electrical resistance measurements are shown in Table G4 for sample G1. * Sample G2 shows an improvement compared to its P 5+ Al 3+ Similar sheet resistances were observed between samples G6 and G7, since they already have oxygen deficiencies due to the subvalent substitution by . Electrochemical measurements further show significant advantages in specific capacity, first and second cycle coulombic efficiency, polarization, and capacity retention at high rates for sample G7 over G6 in Tables G5 and G6.

[0268] It is expected that similar advantages will be observed with any of the presently described PNO structures with induced oxygen vacancies for use in Li-ion cells.

[0269] Reference Example 3E-Sample G1 * , G5, G8, and G10 Sample G5, N 3-Modification by the introduction of anions (see nitridation) has been performed to give sample G8. This was done by a solid-phase synthesis route, but with high-temperature NH 3 This can be done either via a gaseous route using a gas or by using a solvent with the N-containing material dissolved in it, followed by evaporation and subsequent high temperature heat treatment. Sample G8 is brown in color compared to the off-white / light yellow sample G5, and shows a change in the electronic structure of the active material similar to that of Reference Example 3D.

[0270] As in Examples 3A to 3C, this exchange 2- This may occur at anionic sites, in which case the increased valence may increase the electronic conductivity of the material. This may also occur at interstitial sites within the crystal structure. In either case, this may result in different unit cell sizes and associated crystallographic distortions due to the different ionic radii and valences of the anions, providing similar potential benefits as in Examples 3A-3D.

[0271] Table G2 shows the N for sample G8 compared to sample G5. 3- The change in unit cell parameters that occurs after the introduction of anions is shown. The a and b parameters decrease significantly, while the c parameter increases slightly, indicating the incorporation of N into the crystal structure. 3- Evidence of the introduction of . Electrochemical measurements show an improvement in the capacity retention at high rates for sample G8 versus G5 (Table G6). Reference sample G1 * In comparison, sample G8 has a significantly improved capacity retention rate at high rates.

[0272] Comparison sample G1 * , F - The anion was introduced to obtain sample G10. Electrochemical measurements were performed on sample G10. * It shows a significant improvement in capacity retention at high rates compared to the conventional method (Table G6).

[0273] It is expected that similar benefits will be observed using anions of different electronegativity and valency with any of the PNO structures described herein for use in Li-ion cells.

[0274] Consideration Comparison sample G1 * can also be modified with multiple types of cation / anion substitutions or induced oxygen vacancies (i.e., a>0 and b>0, or a>0, d>0, or a>0, b>0, c>0, etc.). Sample G6 shows the effect of having a>0 and b>0, and sample G7 shows the effect of having a>0, b>0, and c>0. Additionally, materials with d>0 are expected to provide additional performance benefits to the active material. For those materials that exhibit multiple types of modifications, the improvements described for Reference Examples 3A-3E are expected.

[0275] Table G2 shows the changes in unit cell parameters reflecting the modifications made to these materials. As shown in Table G4, both Samples G6 and G7 have the same structure as Sample G1. * Electrochemical measurements further show a significant improvement in electrical resistance over the 100% Cr-Al-N-N-Pb-N-Pb-N-100% Cr-Al ... * vis-a-vis sample G7, it shows a significant advantage in specific capacity, second cycle coulombic efficiency, polarization (for sample G7), and capacity retention at high rates.

[0276] Introducing increased disorder into the crystal structure (see entropy) can aid the reversible lithiation process by reducing the large energy barrier to reversible lithiation and by preventing Li-ion ordering within the partially lithiated crystal. This can also be defined as creating a spread in the energy states for Li-ion intercalation, which prevents unfavorable lithium ordering and entropic energy barriers.

[0277] It is expected that similar advantages would be observed in any of the PNO structures described herein using any combination of M6, M7, Q, a, b, c, and d for use in Li-ion cells, within the limitations of the present description.

[0278] Reference examples related to formula 4 The following reference example shows the unmodified "base" MoNb 12 O 33 and WNb 12 O 33 This is achieved by substituting M10 for Nb and / or O for Q, and optionally further substituting M8 for M9 and / or induced oxygen vacancies. It is expected that the same improvements will be seen when the modified mixed niobium oxides are combined with niobium oxides in accordance with the present invention.

[0279] These mixed niobium oxides were synthesized by a solid-state route. In the first step, the precursor material (Nb 2 O 5 , N.H. 4 H 2 PO 4 , MoO 3 , Al 2 O 3 , WO 3 , ZrO 2 ZnO) were mixed in a stoichiometric ratio (50 g total) and ball milled at 350 rpm with a ball to powder ratio of 10:1 for 1 hour. The resulting powder was heated in an alumina crucible in a muffle furnace at 37° C. in air at 200° C. for 1 hour. 1a = 250 to 900 °C for 1 to 12 hours, followed by T 1b = 700-1350 °C for 2-16 hours to obtain the desired Wadsley-Roth phase. In some cases, further heat treatment steps were also performed using N 2 Under the atmosphere, T 2 = 800-1350 °C for 1-12 hours. Further milling / mixing of the precursors to include anions (for the parent material, for N, C 3 H 6 N 6 For F, PVDF was used in a mass ratio of 1:3, and for F, PVDF was used in a mass ratio of 1:10.2 Or in air, T 2 Heat treatment was performed at 300 to 1200°C for 1 to 24 hours.

[0280] If necessary, a final deagglomeration step by impact milling or jet milling was used to adjust the desired particle size distribution. Specifically, the material was deagglomerated by impact milling at 20,000 RPM for 10 seconds. [Table 17]

[0281] Material characterization The phase purity of the samples was analyzed using a Rigaku Miniflex powder X-ray diffractometer at a scan rate of 1° / min in the 2θ range (10–70°).

[0282] Figure H1 shows the XRD diffraction patterns measured for samples H1, H2, H5, H10, H13, H14, and H17. The diffraction patterns have peaks at the same positions (with some shifts due to crystallographic modifications up to about 0.2°) and are consistent with the ICDD Crystallography Database entry JCPDS, which corresponds to JCPDS 73-1322. There is no amorphous background noise and the peaks are sharp and intense. This indicates that all samples are crystalline, with crystallite sizes according to the Scherrer formula of 35-42 nm and a crystal structure of MoNb 12 O 33 or isomorphic WNb 12 O 33 This confirms the presence of the Wadsley-Roth crystal structure. [Table 18]

[0283] 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 H1.

[0284] Confocal Raman spectroscopy was performed on selected samples. Laser excitation 532 nm, attenuation 10% and magnification 50 were used on a Horiba Xplora Plus Raman microscope, samples were pressed into pellets at 10 MPa pressure and placed on glass slides. Spectra were collected over the spectral range 0–2500 cm, with 15 s collection time averaged per scan, three repetitions, and three different sample positions. -1 Recorded at . x O y The peak characteristic of the seed-containing structure is in the range of 500–700 cm -1 The peaks associated with the long Nb-O bonds in the corner-sharing octahedral units are seen in the region of 760–770 cm -1 , and the peaks related to the distorted octahedral species related to O=Nb-O are at 890-900 cm -1 , and peaks associated with shorter Nb–O bonds such as edge-sharing octahedra at 1000 cm -1 It is noteworthy that sample H2 ** is about 650cm -1 The peaks in the SiO2–O–Nb–O ...

[0285] Electrochemical characterization Electrochemical testing was performed in analytical half coin cells (CR2032 size). In the half coin test, active materials are tested against a Li metal electrode to evaluate their fundamental performance. In the following reference examples, the test active material compositions were combined with N-methylpyrrolidone (NMP), carbon black (Super P) acting as a conductive additive, and poly(vinyl difluoride) (PVDF) binder and mixed using a laboratory scale centrifugal planetary mixer to form slurries. The non-NMP composition of these slurries was 92 wt% active material, 3 wt% conductive additive, and 5 wt% binder. The slurries were doctor blade coated onto Al foil current collectors at the desired loading of 69-75 gm.-2 These electrodes were then coated with 2.6 to 3.2 gcm -3 The electrodes were then punched to the desired size and packed into a steel coin cell casing containing a separator (Celgard porous PP / PE), Li metal, and electrolyte (1.3 M LiPF 6 The cells were then mated with an EC / DEC containing 1.1-3.0 V and sealed under pressure. They were then cycled at 23°C at a low current rate (C / 10) for two full cycles of lithiation and delithiation from 1.1 to 3.0 V. The performance of these cells was then examined at increasing current densities. During these tests, the cells were asymmetrically cycled at 23°C with slow lithiation (C / 5) followed by increasing delithiation rates (e.g., 5C) to obtain the nominal voltage at 5C. The nominal voltage vs Li / Li+ was calculated from the integral of the V / Q curve divided by the total capacity at 5C during delithiation. No constant voltage step was used. Data are averaged from five cells prepared from the same electrode composition, with errors shown from standard deviations. Thus, these data represent a robust test showing the improvements achieved by the modified mixed niobium oxides compared to conventional materials.

[0286] The electrical resistivity of the electrode compositions was evaluated individually by the four-point probe method using an Ossila instrument. For all samples, the electrode composition was applied to an insulating Mylar sheet at a mass loading of 69–75 g cm -2 and calendered to a porosity of 35-40%. The sheet resistance was then measured in Ω / square on a 14 mm diameter disk at a constant temperature of 23 °C.

[0287] Homogeneous, smooth, visible defect and agglomerate free coatings on both Cu and Al current collector foils may also be prepared for these samples in a centrifugal planetary mixer as described above with compositions up to 94 wt% active material, 4 wt% conductive additive, and 2 wt% binder. These can be prepared with both PVDF (i.e., NMP-based) and CMC:SBR-based (i.e., aqueous) binder systems. These coatings are calendered at 80°C for PVDF and 50°C for CMC:SBR and are deposited at 1.0-5.0 mAhcm. -2 Porosity of 35-40% can be achieved at loadings of 1000 μm, which is important for achieving high active material content and demonstrating the viability of these materials in both high energy and high power applications. [Table 19] [Table 20]

[0288] Reference Example 4A - Cation Exchange In samples H3 to H9, NbO 6 Nb in a 3x4 block of octahedra 5+ Focusing on the cation, mixed niobium oxides have been modified by a cation exchange approach. For samples H3-H6, the exchange is with a cation with reduced valence. Samples H7-H8 show increased valence, and sample H9 shows isovalent exchange. This is expected to provide benefits over the base crystal structure of sample H1 through a combination of (a) altered ionic radius, (b) altered valence, and (c) altered voltage. The altered ionic radius may provide beneficial changes in electrochemical performance due to altered unit cell size and local distortion of the crystal structure, altering the available lithiation sites or lithiation pathways, potentially improving coulombic efficiency, capacity, high rate performance, and lifetime. For example, in sample H5, 6-coordinated Nb 5+ The ionic radius of the cation is 0.64 Å, while the 6-coordinate Al 3+The ionic radius of the cation is 0.54 Å. The cation exchange was performed on the unmodified sample H as shown in Table H3. * The electrical conductivity of the material is greatly improved compared to the base MoNb, which is believed to be due to providing intermediate energy levels available for charge carriers. This in turn is believed to result in improved performance at high charge and discharge rates and lower nominal voltage at high rates due to lower polarization in the cell. If substitutions are made at the same cation positions, the O content of the material is proportionally reduced in order to maintain a charge balanced structure (i.e., compared to the base MoNb 12 O 33 The voltage can be further modified by introducing cations with different electrochemical redox potentials, allowing the design of materials that give lower nominal voltages.

[0289] Table H2 shows the changes in unit cell parameters observed after cation exchange, i.e., due to changes in the ionic radius and electronic structure of these materials.

[0290] It is anticipated that similar benefits will be observed with the cation exchange approach described herein for this material for use in Li-ion cells.

[0291] Reference Example 4B - Anion Exchange The mixed niobium oxide is 3- Modification by the introduction of anions (see nitridation) has been performed to obtain sample H10. This was done by a solid-phase synthesis route, but with high-temperature NH 3 This can be done either by gas route or by using a solvent with N-containing material dissolved in it, followed by evaporation and subsequent high temperature heat treatment. Sample H10 is an off-white version of Sample H2. ** 4A.

[0292] Similar to the cation-exchanged Example 4A, this exchange was carried out with O 2-This can occur at anion sites, in which case the increased valence can increase the electronic conductivity of the material. This can also occur at interstitial sites in the crystal structure. In either case, this can lead to different unit cell sizes and associated crystallographic distortions due to the different ionic radii and valences of the anions, resulting in potential benefits similar to those of Reference Example 4A.

[0293] Similarly, F - The mixed niobium oxides can be modified by the introduction of anions to give samples H12 and H13, which provide advantages in coulombic efficiency over the reference samples H1 and H2.

[0294] Table H2 shows the 3- Anion or F - The changes in unit cell parameters that occur after the introduction of anions are shown, providing further evidence of the incorporation of anions within the crystal structure.

[0295] Figure H2 further shows that in the Raman spectrum, -1 The evidence of N or F incorporation is shown by the change in the characteristic peak corresponding to the Nb-O bond at .

[0296] It is expected that similar benefits will be observed using anions of different electronegativity and valence with any of the MNO structures described herein for use in Li-ion cells.

[0297] Reference Example 4C - Induced oxygen vacancy defects Samples H5, H7, and H10 have been modified via the introduction of induced oxygen vacancy defects (see oxygen defects) by heat treatment in an inert or reducing atmosphere to obtain samples H14, H15, and H17. By treating these materials at high temperatures in an inert or reducing atmosphere, they are partially reduced, which can be maintained even after returning to room temperature and exposure to an air atmosphere. This is accompanied by a clear color change, e.g., purple / blue for sample H15, whereas white for sample H7. This color change indicates a significant change in the electronic structure of the material that allows it to interact with visible light of different energies (i.e., wavelengths) due to a reduction in the band gap. This is reflected in sample H14, which showed a decrease in the nominal voltage at a rate of 5C, which corresponds to a decrease in the polarization level of the cell.

[0298] Induced oxygen vacancies are specifically defects in the crystal structure where an oxygen anion has been removed, and the overall redox state of the cations is then reduced. This provides an additional energy state that significantly improves the electrical conductivity of the material, and shifts the band gap energy as indicated by the color change. If induced oxygen vacancies are present in excess of 5 atomic % (i.e., c>1.65), the stability of the crystal structure may be reduced. These induced oxygen vacancies may be in addition to the oxygen defects caused by the use of subvalent cation exchange, as shown in sample H14.

[0299] Evidence of oxygen vacancies is provided here by the Raman spectrum in Figure H2, as in Example 4B. Many other techniques can also be used to quantify oxygen vacancies, as described above.

[0300] It is anticipated that similar benefits will be observed with the oxygen vacancy induction approach described herein for this material for use in Li-ion cells.

[0301] Consideration Comparison sample H1 * or H2 **can also be modified with multiple types of cation / anion substitutions or induced oxygen vacancies (i.e., a>0 and b>0, or a>0, d>0, or a>0, b>0, c>0, etc.). Samples H3-H9 show the effect of having a>0 and b>0, and sample H16 shows the effect of having a>0, b>0, and c>0, and d>0. For those materials that show multiple types of modifications, the improvements described for Reference Examples 4A-4C are expected.

[0302] Table H2 shows the changes in unit cell parameters for the modified materials that reflect the changes made to these materials at the crystal level. As shown in Table H3, all samples were * Electrochemical measurements further show a significant improvement in electrical resistance with respect to the modified samples, as seen in Table H4. * 10 shows a significant advantage in first and second cycle coulombic efficiency and nominal voltage at a delithiation rate of 5C over sample H2 ** By modifying the , the specific capacity is improved, a key result that demonstrates the utility of the modified material for use as an active electrode material.

[0303] Modifying the "base" material by introducing increased disorder into the crystal structure (see entropy) can aid the reversible lithiation process by reducing the large energy barrier to reversible lithiation and by preventing Li-ion ordering within the partially lithiated crystal. This can also be defined as creating a spread in the energy states for Li-ion intercalation, which prevents unfavorable lithium ordering and entropic energy barriers. This can be inferred by examining dQ / dV or from cyclic voltammetry plots.

[0304] It is expected that similar advantages will be observed in any of the MNO structures described herein using any combination of M8, M9, M10, Q, a, b, c, and d for use in Li-ion cells, within the limitations of the present description.

[0305] Further references related to formula 4 The following reference example shows the unmodified "base" MoNb 12 O 33 and WNb 12 O 33 This is achieved by substituting M8 with M9 and / or induced oxygen vacancies. It is expected that the same improvement will be seen when the modified mixed niobium oxide is combined with a niobium oxide in accordance with the present invention.

[0306] Many different materials were prepared and characterized, as summarized in Table I1 below. These samples can be broadly divided into several groups. Samples I1, I2, I3, I4, I5, I8, I9, I10, I11, and I12 are MoNb 12 O 33 (M 6+ Nb 12 O 33 It belongs to the family of Wadsley-Roth phases based on 3x4 blocks of octahedrons with tetrahedrons at the corners of each block. These blocks are NbO 6 Sharing of edges between octahedra and M 6+ O 4 Tetrahedron and NbO 6 The octahedra are connected to each other by corner sharing between them. Sample I1 is the base crystal structure, which is modified to a mixed metal cation structure by exchanging one or more cations in samples I2-I4 and / or to a mixed crystal configuration (isomorphous WNb 12 O 33The base crystal of sample R5 and the mixed metal cation structure I11 are modified to have oxygen vacancies. Sample I3 is a spray-dried and carbon-coated version of the crystals made in sample I2, and sample I12 is a spray-dried and carbon-coated version of the crystals made in sample I10. Samples I6, I7, and I13 are WNb 12 O 33 (M 6+ Nb 12 O 33 , 3x4 NbO with tetrahedrons at the corners of each block 6 It belongs to the family of Wadsley-Roth phases based on octahedral blocks. [Table 21]

[0307] material synthesis The samples listed in Table I1 were synthesized using a solid-state route. In the first step, commercially available powders of metal oxide precursors (Nb 2 O 5 , NbO 2 , MoO 3 , ZrO 2 , TiO 2 , WO 3 , V 2 O 5 , ZrO 2 , K 2The stoichiometric ratios of ZnO, CoO, ZnO, and / or MgO were mixed and subjected to a planetary ball mill with a ball-to-powder ratio of 10:1 in a zirconia jar and milling media at 550 rpm for 3 h. The resulting powders were then heated in air in a static muffle furnace to form the desired crystalline phases. Samples I1-I5 and I8-I12 were heat treated at 900 °C for 12 h, and samples I6-I7 were heat treated at 1200 °C for 12 h. Samples I3 and I12 were further mixed with carbohydrate precursors (e.g., sucrose, maltodextrin, or other water-soluble carbohydrates), dispersed in aqueous slurries at concentrations of 5, 10, 15, or 20 w / w% with an ionic surfactant, and 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 I5 and I11 were further annealed in nitrogen at 900° C. for 4 hours.

[0308] Sample I13 was adjusted to a particle size distribution of D90<20 μm using the ball mill described above and, if necessary, an impact mill at 20,000 rpm, and heat treated in air at 1200° C. for 12 hours in a muffle furnace or the like, and then further annealed in nitrogen at 1000° C. for 4 hours.

[0309] XRD characterization of samples The phase purity of some samples was analyzed using a Rigaku Miniflex powder X-ray diffractometer in the 2θ range (10–70°) at a scan rate of 1° / min.

[0310] Figure I1 shows the XRD diffraction patterns measured for samples I1, I4, I8, I2, I5, I9, I10, I11, and I12 related to Comparative Test A. All diffraction patterns have peaks at the same positions (within 0.1° instrumental error) and are consistent with the JCPDS crystallography database entry JCPDS 73-1322. There is no amorphous background noise and the peaks are sharp and intense. This indicates that all samples are phase pure and crystalline, with crystallite sizes of approximately 200 nm according to the Scherrer formula and crystal structures of MoNb 12 O 33means to match

[0311] Figure I2 shows the XRD diffraction patterns measured for samples I6 and I7. All diffraction patterns have peaks at the same positions (within 0.1° instrumental error) and are consistent with the JCPDS Crystallography Database entry JCPDS 73-1322. There is no amorphous background noise and the peaks are sharp and intense. This indicates that all samples are phase pure and crystalline, with crystallite sizes of approximately 200 nm according to the Scherrer formula and crystal structure of WNb 12 O 33 means to match

[0312] Qualitative evaluation of oxygen vacancies As discussed above, samples I5 and I11 were heat treated at 900° C. for 12 hours to form the active electrode material and then further annealed in nitrogen (a reducing atmosphere) in a post-treatment heat treatment step at 900° C. A color change from white to deep purple was observed after the post-treatment heat treatment in nitrogen, indicating a change in the oxidation state and band structure of the material as a result of oxygen deficiencies in the samples.

[0313] Sample I13 was further annealed in nitrogen at 1000° C. for 4 hours. Sample I6 transitions from off-white to light blue in I13.

[0314] Electrochemical testing of samples Electrochemical testing was performed in early stage analytical half coin cells (CR2032 size). In the half coin test, materials are tested electrode against a Li metal electrode to evaluate their basic performance. In the following reference examples, the test active material compositions were combined with N-methylpyrrolidone (NMP), carbon black, which acts as a conductive additive, and poly(vinyl difluoride) (PVDF) binder, and mixed using a laboratory scale centrifugal planetary mixer to form slurries (water can also be used rather than NMP to form aqueous slurries). The non-NMP composition of these slurries was 80 wt% active material, 10 wt% conductive additive, 10 wt% binder. This slurry was then doctor blade coated onto an Al foil current collector at the desired loading of 1 mg / cm. 2 The electrodes were punched to the desired size and packed in a steel coin cell casing with a separator (Celgard porous PP / PE), Li metal, and electrolyte (1M LiPF 6 The cells were combined with an EC / DEC containing 100% EDTA and sealed under pressure. Formation cycles were then performed with two full charge and discharge cycles at a low current rate (C / 20). After formation, further cycles can be performed at fixed or varying current densities as required. These tests are referred to as "half-cell galvanostatic cycling" for future reference. Also, homogeneous, smooth, visible defect-free coatings on current collector foils were prepared using a centrifugal planetary mixer as described above with a composition of 94 wt% active material, 4 wt% conductive additive, and 2 wt% binder. These coatings have been shown to have a volumetric capacity of >700 mAh / cm2 in the voltage range of 0.7-3.0 V at C / 20. 3 , and >640mAh / cm at C / 5 in the voltage range 1.1-3.0V 3 To show this, the capacity is 1.3 to 1.7 mAh / cm at 80°C. 2 Maximum density 3.0g / cm 3This is an important demonstration of the viability of these materials in power cell formulations with commercially attractive electrodes where performance is maintained at high electrode densities after calendaring, enabling high volumetric capacities of 1.0, 1.5, 2.0, 2.5, or 3.0 mAh / cm. 2 Loads below this, including 3.0, 4.0, or 5.0 mAh / cm, may be useful for Li-ion cells with a focus on power performance. 2 Loadings above 0.01% are useful for energy-critical performance in Li-ion cells. Calendering of these materials has been demonstrated with electrode porosity values ​​up to 35%, typically in the range of 35-40%, defined as a measure of electrode density divided by the average true density adjusted for w / w% of each electrode component. Some of the data obtained in the further reference examples related to Equation 4 may not have been obtained under identical conditions as the data obtained in the reference examples. Thus, absolute values ​​obtained in the reference examples and further reference examples may not be directly comparable.

[0315] The electrical conductivity of the electrodes made from the samples listed in Table I1 was measured using a four-point probe thin film resistance measurement device. Slurries were prepared according to the procedure above, and the concentration was 1 mg / cm 2 The coated film was coated on a dielectric Mylar film at a load of 0.01 V. The electrode-sized disks were then punched out and the resistance of the coated film was measured using a four-point probe. The bulk resistivity can be calculated from the measured resistance using the following formula: (3) Bulk resistivity (ρ)=2πs(V / I); R=V / I, s=0.1cm =2πx0.1xR(Ω)

[0316] The results of this test are shown in Table I2 below. [Table 22]

[0317] The results of this test are shown in Table I3 below. [Table 23]

[0318] Additionally, the reversible specific capacity C / 20, initial coulombic efficiency, and nominal lithiation voltage at C / 20 vs Li / Li were measured for several samples. + , 5C / 0.5C capacity retention, and 10C / 0.5C capacity retention were also investigated and the results are shown in Table I4 below. The nominal lithiation voltage vs Li / Li+ was calculated from the integral of the V / Q curve divided 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. It should be noted that the capacity retention was investigated using symmetric cycling tests where the C-rates during lithiation and delithiation are equal. In tests using asymmetric cycling programs, 10C / 0.5C capacity retentions of over 89% are typically observed. [Table 24]

[0319] The above MoNb 12 O 33 and WNb 12 O 33 The modification of demonstrates the applicability of cation substitution to improve the performance of active materials in Li-ion cells. By substituting non-Nb cations as described to form mixed cation structures, entropy (see disorder) can be increased in the crystal structure and the potential energy barrier for Li-ion diffusion can be reduced through the introduction of minor defects (e.g., I10). Modification by creating mixed cation structures while maintaining the overall oxidation state demonstrates the potential for improvement by changing the ionic radius, e.g., the Mo in sample I8. 6+ Cation W 6+Substitution with Mo may result in minor changes in crystal parameters and Li-ion cavities (e.g., tuning the reversibility of the Type VI cavities in the Wadsley-Roth structure), which may improve the specific capacity, Li-ion diffusion, and increase the coulombic efficiency of cycling due to reduced Li-ion trapping. Modifications by creating mixed cation structures resulting in an increase in oxidation states are expected to demonstrate similar potential benefits of changing the ionic radius in relation to capacity and efficiency, combined with the introduction of additional electron holes into the structure to aid electrical conductivity. Modifications by creating mixed cation structures resulting in a decrease in oxidation states (e.g., tuning the reversibility of the Type VI cavities in the Wadsley-Roth structure) may result in minor changes in crystal parameters and Li-ion cavities (e.g., tuning the reversibility of the Type VI cavities in the Wadsley-Roth structure), which may improve the specific capacity, Li-ion diffusion, and increase the coulombic efficiency of cycling due to reduced Li-ion trapping. 6+ Substituting Ti 4+ ) demonstrate similar potential benefits of altering ionic radius in relation to capacity and efficiency in combination with the introduction of oxygen vacancies and additional electrons into the structure to aid electrical conductivity. Modification by inducing oxygen vacancies from high temperature treatment under inert or reducing conditions demonstrates loss of a small fraction of oxygen from the structure resulting in a reduced structure with significantly improved electrical conductivity (e.g., sample I5) and improved electrochemical properties, e.g., capacity retention at high C-rates (e.g., sample I5). The combination of mixed cation structure and induced oxygen vacancies can compound multiple beneficial effects (e.g., increased specific capacitance, reduced electrical resistance) (e.g., sample I11).

[0320] The composite metal oxide sample I10 demonstrates an improvement in specific capacity compared to its unmodified crystalline sample I1. This is due to the fact that the cations contained in the composite structure increase the number of sites in the crystal where Li-ions can fit due to their different ionic radii and oxidation states, thereby increasing the capacity. An increase in ICE was observed between samples I1 and I10. This further demonstrates that Li-ions intercalated into the modified crystalline structure can be delithiated more efficiently as the Li-ion sites are modified to allow their deintercalation.

[0321] Across all materials examined, each modified material shows an improvement over the unmodified "base" crystal structure. This is inferred from resistivity / impedance measurements by two different methods, as well as electrochemical tests performed on lithium-ion half-coin cells, especially the capacity retention at high current densities (see rate, Table I4). Without wishing to be bound by theory, we suggest that this is a result of the ionic and electronic conductivity of the material increasing as defects are introduced or by modifications to the crystal lattice with different ionic radii, also evidenced by DCIR / ASI (Table I3) measurements to show a decrease in resistance or impedance after modification of the material. The diffusion rate of Li-ions may also increase in the modified material compared to the unmodified "base" material. The specific capacitance itself may also increase in some cases, as shown in Table I4, since doping / exchange with metal ions of different sizes can expand or contract the crystal lattice, allowing for more intercalation of Li-ions or reversibility of more intercalation than is possible in the unmodified structure.

[0322] The data in Table I2 show a large decrease in resistivity between sample I1 (comparative) and samples I2, I4, I5, I8, I9, I10, I11, and I12, demonstrating the effectiveness of modifications to improve electrical conductivity of the crystal structure, both through cation exchange, oxygen vacancies, and carbon coating.

[0323] The data in Table I3 show a large decrease in DCIR / ASI from sample I1 (comparative) to samples I2, I4, I8, I10, I11 and I12, mirroring the trends shown in Table I2.

[0324] In Table I4, across most samples, the specific capacity, initial coulombic efficiency (ICE), and nominal lithiation voltage vs Li / Li are reported for the modified materials versus the comparative “base” materials (e.g., samples I1, I8). +, and capacity retention at 5C and 10C versus 0.5C. For example, samples I2, I3, I4, I5, I8, I9, I10, I11, I12 all show improvements in one or more of these parameters versus sample I1. This is also the case for sample I7 versus I6, which has improved ICE and capacity retention.

Claims

1. 1. An electrochemical cell comprising an anode, a cathode, and an electrolyte disposed between the anode and the cathode, The anode contains an oxide containing niobium as an active anode material, and the crystal structure of the oxide containing niobium is M ＩＩ ２ Nb ３４ O ８７ , M ＩＩＩ Nb １１ O ２９ , M ＩＩＩ Nb ４９ O １２４ , M ＩＶ Nb ２４ O ６２ , M Ｖ Nb ９ O ２５ , M ＶＩ Nb １２ O ３３ , H—Nb ２ O ５ , or N-Nb ２ O ５ corresponds to the crystal structure of The cell has an N / P ratio > 1, where the N / P ratio is: [Equation 1] is defined as During the ceremony, Area loading (mgcm －２ ) is the dry load of the electrode composition without considering the current collector, Active Fraction (wt%) is the percentage of the dry electrode composition that is active material; Initial lithiation / delithiation capacity (mAhg －１ ) is the specific capacity at C / 10 at 25°C for the first lithiation cycle of the anode or the first delithiation cycle of the cathode, measured in an equivalent half-cell with a Li metal counter electrode; The electrochemical cell.

2. 2. The electrochemical cell of claim 1, wherein the N / P ratio is >1 to 2, or 1.01 to 1.5, or 1.05 to 1.

3.

3. The crystal structure of the niobium-containing oxide is M ＩＩ ２ Nb ３４ O ８７ , M ＩＩＩ Nb １１ O ２９ , M Ｖ Nb ９ O ２５ , or H—Nb ２ O ５ or M ＩＩ ２ Nb ３４ O ８７ , M ＩＩＩ Nb １１ O ２９ , or H—Nb ２ O ５ or M ＩＩ ２ Nb ３４ O ８７ 3. The electrochemical cell of claim 1, wherein the crystal structure corresponds to:

4. 3. The electrochemical cell of claim 1 or 2, wherein the niobium-containing oxide forms at least 10%, 50%, or 75% by weight of the total active anode material of the anode.

5. the anode comprises an additional active anode material; 3. An electrochemical cell according to claim 1 or 2, wherein optionally the further active anode material is selected from lithium titanium oxide, titanium niobium oxide, different niobium-containing oxides, graphite, hard carbon, soft carbon, silicon, doped and / or carbon-coated versions thereof, and mixtures thereof.

6. 3. The electrochemical cell of claim 1, wherein the niobium-containing oxide is the only active anodic material of the anode.

7. the cathode comprises an active cathode material; Optionally, the active cathode material is LiNi, where M=Co, Mn, Al. １－ｘ M ｘ O ２ 3. An electrochemical cell according to claim 1 or 2, wherein the nickel-based layered oxide is selected from the classes of nickel-based layered oxides, such as NMC, i.e., lithium nickel manganese cobalt oxide, NCA, i.e., lithium cobalt aluminum oxide, and LCO, i.e., lithium cobalt oxide, and LNMO, i.e., lithium nickel manganese oxide.

8. The niobium-containing oxide is represented by the formula M1 ａ M2 ２－ａ M3 ｂ Nb ３４－ｂ O ８７－ｃ－ｄ Q ｄ and During the ceremony, M1 and M2 are different, M1 is selected from Mg, Ca, Sr, Y, La, Ce, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Fe, Co, Ni, Cu, Zn, Cd, B, Al, Ga, In, Si, Ge, Sn, Pb, P, Sb, Bi, and mixtures thereof; M2 is Zn or Cu; M3 is selected from Mg, Ca, Sr, Y, La, Ce, Ti, Zr, Hf, V, Ta, Cr, Mo, W, Mn, Fe, Co, Ni, Cu, Zn, Cd, B, Al, Ga, In, Si, Ge, Sn, Pb, P, Sb, Bi, and mixtures thereof; Q is selected from F, Cl, Br, I, N, S, Se, and mixtures thereof; 0≦a<1.0, 0≦b≦3.4, −0.5≦c≦4.35, 0≦d≦4.35, one or more of a, b, c, and d is not equal to 0; If a, b, and d are 0, then c is greater than 0; 3. The electrochemical cell of claim 1 or 2.

9. The niobium-containing oxide is represented by the formula M1 ａ Zn ２－ａ M3 ｂ Nb ３４－ｂ O ８７－ｃ and During the ceremony, M1 is selected from Mg, Zr, V, Cr, Mo, W, Fe, Cu, Al, Ge, P, and mixtures thereof; M3 is selected from Ti, Zr, V, Cr, Mo, W, Fe, Cu, Zn, Al, P, and mixtures thereof; 0<a<1.0, 0<b≦3.4, −0.5≦c≦4.35; 9. The electrochemical cell of claim 8.

10. The niobium-containing oxide is represented by the formula M1 ａ M2 ２－ａ M3 ｂ Nb ３４－ｂ O ８７－ｃ and During the ceremony, M1 is selected from Cr, Al, Ge, and mixtures thereof, preferably M1 is Cr; M2 is Zn or Cu, preferably M2 is Zn; M3 is selected from Ti, Zr, Fe, and mixtures thereof, optionally including Ti; preferably, M3 is selected from Ti, Zr, and mixtures thereof, optionally including Ti; most preferably, M3 is Ti; 0<a<1.0, preferably 0.01<a<1.0, 0<b≦1.5, preferably 0.01<b<1.0; -0.5≦c≦4.35, preferably -0.5≦c≦2, most preferably c=0; 9. The electrochemical cell of claim 8.

11. The niobium-containing oxide has the formula Cr ａ Zn ２－ａ M3 ｂ Nb ３４－ｂ O ８７－ｃ and During the ceremony, M3 is selected from Ti, Zr, and mixtures thereof, optionally including Ti, preferably M3 is Ti; 0.01<a<1.0, preferably 0.1<a<1.0; 0.01<b<1.0, preferably 0.1<b<1.0; -0.5≦c≦2, preferably c=0; 9. The electrochemical cell of claim 8.

12. The niobium-containing oxide is represented by the formula M4 ａ Al １－ａ M5 ｂ Nb １１－ｂ O ２９－ｃ－ｄ Q ｄ and During the ceremony, M4 is selected from Mg, Ca, Sr, Y, La, Ce, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Fe, Co, Ni, Cu, Zn, Cd, B, Ga, In, Si, Ge, Sn, Pb, P, Sb, Bi, and mixtures thereof; M5 is selected from Mg, Ca, Sr, Y, La, Ce, Zr, Hf, V, Ta, Cr, Mo, W, Mn, Fe, Co, Ni, Cu, Zn, Cd, B, Al, Ga, In, Si, Ge, Sn, Pb, P, Sb, Bi, and mixtures thereof; Q is selected from F, Cl, Br, I, N, S, Se, and mixtures thereof; 0≦a<0.5, 0≦b≦1, −0.5≦c≦1.45, 0≦d≦1.45, one or more of a, b, and d is not equal to 0; 3. The electrochemical cell of claim 1 or 2.

13. The niobium-containing oxide is represented by the formula M4 ａ Al １－ａ Nb １１ O ２９－ｃ－ｄ Q ｄ and During the ceremony, M4 is selected from Mg, Zr, V, Cr, Mo, W, Mn, Fe, Co, Ni, Cu, Zn, B, Ga, Si, Ge, P, and mixtures thereof; Q is selected from F, N, and mixtures thereof; 0<a<0.5, 0≦c≦1.45, and 0≦d≦1.45; 13. The electrochemical cell of claim 12.

14. The niobium-containing oxide is represented by the formula M6 ａ P ｘ－ａ M7 ｂ Nb ９－ｂ O ２５－ｃ－ｄ Q ｄ and During the ceremony, M6 is selected from Na, K, Mg, Ca, Sr, Y, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Fe, Co, Ni, Cu, Zn, B, Al, Ga, Si, Ge, Sn, Bi, Sb, and mixtures thereof; M7 is selected from Na, K, Mg, Ca, Sr, Y, Ti, Zr, Hf, V, Ta, Cr, Mo, W, Mn, Fe, Co, Ni, Cu, Zn, B, Al, Ga, Si, Ge, Sn, Bi, P, Sb, and mixtures thereof; Q is selected from F, Cl, Br, I, N, S, Se, and mixtures thereof; 0≦a≦0.5, 0≦b≦2, −0.5≦c≦1.25, 0≦d≦5, 1≦x≦2, one or more of a, b, c, and d is not equal to 0; However, when M6 is made of Nb and M7 is made of P, c is > 0.

3. The electrochemical cell of claim 1 or 2.

15. The niobium-containing oxide is represented by the formula M6 ａ P １－ａ M7 ｂ Nb ９－ｂ O ２５－ｃ－ｄ Q ｄ and During the ceremony, M6 is selected from Ti, Zr, Hf, Cr, Mo, W, B, Al, Ga, Ge, Bi, Sb, and mixtures thereof; M7 is selected from Ti, Zr, Hf, Cr, Mo, W, V, Ta, Ga, Ge, and mixtures thereof; Q is selected from F, N, and mixtures thereof; 0≦a≦0.2, 0≦b≦1, 0≦c≦1.25, 0≦d≦2.5, At least one of a and b is >0; 15. The electrochemical cell of claim 14.

16. The niobium-containing oxide is represented by the formula M8 ａ M9 １－ａ M10 ｂ Nb １２－ｂ O ３３－ｃ－ｄ Q ｄ and During the ceremony, M8 and M9 are different, M8 is selected from Mg, Ca, Sr, Y, La, Ce, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Fe, Co, Ni, Cu, Zn, Cd, B, Al, Ga, In, Si, Ge, Sn, Pb, P, Sb, Bi, and mixtures thereof; M9 is Mo or W; M10 is selected from Mg, Ca, Sr, Y, La, Ce, Ti, Zr, Hf, V, Ta, Cr, Mo, W, Mn, Fe, Co, Ni, Cu, Zn, Cd, B, Al, Ga, In, Si, Ge, Sn, Pb, P, Sb, Bi, and mixtures thereof; Q is selected from F, Cl, Br, I, N, S, Se, and mixtures thereof; 0≦a<0.5, 0≦b≦2, −0.5≦c≦1.65, 0≦d≦1.65, one or more of a, b, c, and d is not equal to 0; If a, b, and d are 0, then c is greater than 0; 3. The electrochemical cell of claim 1 or 2.

17. The niobium-containing oxide is represented by the formula M8 ａ M9 １－ａ M10 ｂ Nb １２－ｂ O ３３－ｃ－ｄ Q ｄ and During the ceremony, M8 and M9 are different, M8 is selected from Ti, Zr, V, Cr, Mo, W, Fe, Cu, Zn, Al, P, and mixtures thereof; M9 is Mo or W; M10 is selected from Ti, Zr, V, Cr, Mo, W, Fe, Cu, Zn, Al, P, and mixtures thereof; Q is selected from F, N, and mixtures thereof; 17. The electrochemical cell of claim 16, wherein 0<a≦0.45, 0≦b≦0.2, −0.25≦c≦1.65, and 0≦d≦0.

8.

18. The niobium-containing oxide is H—Nb ２ O ５ That is, 3. The electrochemical cell of claim 1 or 2.

19. a metal ion battery, optionally a lithium ion or sodium ion battery; 3. The electrochemical cell of claim 1 or 2.

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