A rutile-type TiNbO4 negative electrode material, its preparation method and application

Abstract

The present invention provides a rutile-type TiNbO4 anode material, a preparation method thereof and an application. The preparation method of the rutile-type TiNbO4 anode material of the present invention uses a single raw material, namely an inorganic two-dimensional layered double transition metal carbide TiNbC MXene precursor, and the target material TiNbO4 can be prepared by one-step oxidation. This preparation method has the advantages of simple equipment (tube furnace or muffle furnace can be flexibly selected, etc.), simple operation process, no need to add any organic solvents, safety and environmental protection, etc.; the obtained product has a layered stacking structure, high purity and small particle size, and this material shows great application potential as the anode of lithium-ion batteries and sodium-ion batteries.

Description

Technical Field

[0001] The present invention relates to the technical field of battery materials, and particularly to a rutile-type TiNbO4 anode material, a preparation method thereof, and an application thereof. Background Art

[0002] Alkali metal ion batteries (especially lithium / sodium ion batteries), as rechargeable batteries, are one of the important energy storage technologies at present. Due to their advantages such as light weight, high energy density, high working voltage, no "memory effect", small self-discharge, and long cycle life, they have received extensive attention in recent years. With the increasingly wide application of electric vehicles, portable consumer electronics products, and energy storage systems, the demand for lithium / sodium batteries has increased accordingly, and the performance requirements for them have become increasingly high. Electrode materials are one of the most important factors affecting the performance of alkali metal ion batteries. Seeking electrode materials with high specific capacity and stable structure is the key to promoting the development of alkali metal ion batteries.

[0003] As an intercalation-type anode material, niobium titanate compounds (titanium niobium oxides, including TiNb2O7, Ti2Nb2O9, TiNb 24 O 629 and Ti2Nb 10 O2, etc.) have high specific capacity, safe lithium intercalation potential, fast lithium intercalation channels, and stable lithium intercalation structures, and have become a hot spot for researching anodes of high-power and long-life lithium-ion power batteries. The crystal structures of niobium titanate materials reported currently mainly belong to the monoclinic shear ReO3-type crystal structure, that is, titanium and niobium atoms coordinate with oxygen to form octahedrons (NbO6 / TiO6), and are connected through the edges or vertices of the octahedrons, and the formed gaps constitute the lithium intercalation space. However, their low electronic conductivity limits the high-rate performance of niobium titanate anode materials.

[0004] TiNbO4 is a recently discovered Li host material. Different from most mixed oxides of Ti and Nb, TiNbO4 has no phase change for lithium storage. It stores lithium ions through a pure single-phase reaction. Therefore, this new type of electrode material with pure single-phase metal ion intercalation is of great significance for the development of high-performance anode materials and has great application prospects in the field of metal ion batteries (lithium / sodium / potassium ion batteries). However, currently only a very small number of studies have successfully prepared TiNbO4 and used it in metal ion batteries, and the raw materials for preparing TiNbO4 currently are all organic alkoxides (tetrabutyl titanate and niobium ethoxide), which are expensive, have certain volatility and toxicity, have harsh preparation conditions, and the preparation process is complex, making it difficult to produce on a large scale. Based on this, it is necessary to improve the existing technology. Summary of the Invention

[0005] In view of this, the present invention provides a rutile-type TiNbO4 anode material, a preparation method thereof and an application thereof to solve the defects existing in the prior art.

[0006] In a first aspect, the present invention provides a preparation method of a rutile-type TiNbO4 anode material, comprising the following steps:

[0007] Prepare a two-dimensional layered double transition metal carbide TiNbC MXene precursor;

[0008] Oxidize the two-dimensional layered double transition metal carbide TiNbC MXene precursor at 900-1600 °C for 2-10 h to obtain the rutile-type TiNbO4 anode material.

[0009] Preferably, in the preparation method of the rutile-type TiNbO4 anode material, the preparation method of the two-dimensional layered double transition metal carbide TiNbC MXene precursor comprises the following steps:

[0010] Mix titanium powder, niobium powder, aluminum powder and carbon powder to obtain a mixture;

[0011] Calcine the mixture in a protective atmosphere at 1200-1600 °C for 2-20 h to obtain TiNbAlC;

[0012] Add an etchant to TiNbAlC, keep it warm at 80-120 °C for 12-36 h, wash and dry to obtain the two-dimensional layered double transition metal carbide TiNbC MXene precursor.

[0013] Preferably, in the preparation method of the rutile-type TiNbO4 anode material, the molar ratio of the titanium powder, niobium powder, aluminum powder and carbon powder is (1-1.2):(1-1.2):(1.1-1.3):(0.9-1.1);

[0014] And / or, the molar ratio of the TiNbAlC to the etchant is (0.5-2):(0.5-2).

[0015] Preferably, in the preparation method of the rutile-type TiNbO4 anode material, the etchant comprises at least one of lithium fluoride, sodium fluoride, potassium fluoride, ammonium bifluoride, hydrochloric acid and hydrofluoric acid.

[0016] Preferably, in the preparation method of the rutile-type TiNbO4 anode material, heat the mixture in a protective atmosphere from room temperature to 1200-1600 °C at a rate of 0.5-20 °C / min, and calcine for 2-20 h to obtain TiNbAlC;

[0017] Among them, the protective atmosphere includes at least one of nitrogen, argon, helium, and neon.

[0018] Preferably, in the method for preparing the rutile-type TiNbO4 negative electrode material, in the step of oxidizing the two-dimensional layered double transition metal carbide TiNbC MXene precursor at 900-1600 °C for 2-10 h, the oxidation atmosphere includes any one of air, oxygen, a mixture of oxygen and argon, and a mixture of oxygen and nitrogen.

[0019] Preferably, in the method for preparing the rutile-type TiNbO4 negative electrode material, the two-dimensional layered double transition metal carbide TiNbC MXene precursor is heated from room temperature to 900-1600 °C at a rate of 0.5-20 °C / min and calcined for 2-10 h to obtain the rutile-type TiNbO4 negative electrode material.

[0020] In a second aspect, the present invention also provides a rutile-type TiNbO4 negative electrode material prepared by using the described preparation method.

[0021] In a third aspect, the present invention also provides an application of the rutile-type TiNbO4 negative electrode material prepared by using the described preparation method or the rutile-type TiNbO4 negative electrode material in the preparation of a lithium-ion battery or a sodium-ion battery.

[0022] In a fourth aspect, the present invention also provides a lithium-ion battery or a sodium-ion battery, including the rutile-type TiNbO4 negative electrode material prepared by using the described preparation method or the rutile-type TiNbO4 negative electrode material.

[0023] The present invention has the following beneficial effects compared with the prior art:

[0024] In the method for preparing the rutile-type TiNbO4 negative electrode material of the present invention, a single raw material, namely an inorganic two-dimensional layered double transition metal carbide TiNbC MXene precursor, is used as the raw material, and the target material TiNbO4 can be prepared by one-step oxidation. This preparation method has the advantages of simple equipment (tube furnaces or muffle furnaces can be flexibly selected), simple operation process, no need to add any organic solvents, safety and environmental protection, etc.; the obtained product has a layered stacking structure, high purity, and small particle size, and this material shows great application potential as the negative electrode of lithium-ion batteries and sodium-ion batteries. Description of the Drawings

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the accompanying drawings required in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other accompanying drawings can be obtained based on these drawings.

[0026] Figure 1 XRD pattern of the rutile-type TiNbO4 anode material prepared in Example 1;

[0027] Figure 2 SEM image of the rutile-type TiNbO4 anode material prepared in Example 1;

[0028] Figure 3 Rate performance graph of the lithium-ion battery assembled with the rutile-type TiNbO4 anode material prepared in Example 1;

[0029] Figure 4 Cycling performance graph of the sodium-ion battery assembled with the rutile-type TiNbO4 anode material prepared in Example 1 at 1C;

[0030] Figure 5 XRD pattern of the rutile-type TiNbO4 anode material prepared in Example 2;

[0031] Figure 6 SEM image of the rutile-type TiNbO4 anode material prepared in Example 2;

[0032] Figure 7 XRD pattern of the rutile-type TiNbO4 anode material prepared in Example 3;

[0033] Figure 8 SEM image of the rutile-type TiNbO4 anode material prepared in Example 3. Detailed implementation manners

[0034] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in combination with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0035] It should be noted that the description order of the following embodiments does not limit the preferred order of the embodiments. Additionally, in the description of this application, the term "including" means "including but not limited to". The various embodiments of the present invention may exist in a range form; it should be understood that the description in a range form is only for convenience and brevity, and should not be construed as a rigid limitation on the scope of the present invention; therefore, it should be considered that the described range description has specifically disclosed all possible sub-ranges and individual values within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and individual numbers within the range, such as 1, 2, 3, 4, 5, and 6, which applies regardless of the range. Additionally, whenever a numerical range is indicated herein, it means including any cited number (fraction or integer) within the indicated range.

[0036] An embodiment of the present application provides a method for preparing a rutile-type TiNbO4 anode material, including the following steps:

[0037] S1. Prepare a two-dimensional layered double transition metal carbide TiNbC MXene precursor;

[0038] S2. Oxidize the two-dimensional layered double transition metal carbide TiNbC MXene precursor at 900 - 1600 °C for 2 - 10 h to obtain the rutile-type TiNbO4 anode material.

[0039] The method for preparing the rutile-type TiNbO4 anode material of the present invention uses a single raw material, namely an inorganic two-dimensional layered double transition metal carbide TiNbC MXene precursor, and the target material TiNbO4 can be prepared by one-step oxidation. This preparation method has the advantages of simple equipment (such as a tube furnace or a muffle furnace can be flexibly selected), simple operation process, no need to add any organic solvents, safety and environmental protection, etc.; the obtained product has a layered stacking structure, high purity, and small particle size, and this material shows great application potential as the anode of lithium-ion batteries and sodium-ion batteries.

[0040] In some embodiments, the method for preparing the two-dimensional layered double transition metal carbide TiNbC MXene precursor includes the following steps:

[0041] S11. Mix titanium powder, niobium powder, aluminum powder, and carbon powder to obtain a mixture;

[0042] S12. Calcinate the mixture in a protective atmosphere at 1200 - 1600 °C for 2 - 20 h to obtain TiNbAlC;

[0043] S13. Add an etchant to TiNbAlC, keep it at 80 - 120 °C for 12 - 36 h, wash and dry it to obtain the above-mentioned two-dimensional layered double transition metal carbide TiNbC MXene precursor.

[0044] Specifically, in some embodiments, mix titanium powder, niobium powder, aluminum powder, and carbon powder to obtain a mixture; press the mixture into a block, place it in a high-temperature tube furnace, and heat it to 1200 - 1600 °C under a protective atmosphere for 2 - 20 h, then cool, crush, and screen it to obtain TiNbAlC; put TiNbAlC into a polytetrafluoroethylene inner liner, add an appropriate amount of etchant, put the above mixture into a reaction kettle, heat it to 80 - 120 °C, keep it for 12 - 36 h, then cool, and obtain the two-dimensional layered double transition metal carbide TiNbC MXene precursor after washing and drying.

[0045] In some embodiments, the molar ratio of titanium powder, niobium powder, aluminum powder, and carbon powder is (1 - 1.2):(1 - 1.2):(1.1 - 1.3):(0.9 - 1.1).

[0046] In some embodiments, the molar ratio of TiNbAlC to the etchant is (0.5 - 2):(0.5 - 2).

[0047] In some embodiments, the etchant includes at least one of lithium fluoride, sodium fluoride, potassium fluoride, ammonium bifluoride, hydrochloric acid, and hydrofluoric acid.

[0048] In some embodiments, heat the mixture from room temperature to 1200 - 1600 °C at a rate of 0.5 - 20 °C / min under a protective atmosphere and calcine it for 2 - 20 h to obtain TiNbAlC;

[0049] Among them, the protective atmosphere includes at least one of nitrogen, argon, helium, and neon.

[0050] In some embodiments, in the step of oxidizing the two-dimensional layered double transition metal carbide TiNbC MXene precursor at 900 - 1600 °C for 2 - 10 h, the oxidation atmosphere includes any one of air, oxygen, a mixture of oxygen and argon, and a mixture of oxygen and nitrogen.

[0051] In some embodiments, the volume concentration of oxygen in the mixture of oxygen and argon is 5 - 70%, and the volume concentration of oxygen in the mixture of oxygen and nitrogen is 5 - 70%.

[0052] In some embodiments, a two-dimensional layered double transition metal carbide TiNbC MXene precursor is heated from room temperature to 900 - 1600 °C at a rate of 0.5 - 20 °C / min and calcined for 2 - 10 h to obtain a rutile-type TiNbO4 anode material.

[0053] Based on the same inventive concept, the present invention also provides a rutile-type TiNbO4 anode material prepared by the above preparation method.

[0054] The rutile-type TiNbO4 anode material prepared by the present invention has the advantages of a layered stacking structure, high purity, and small particle size, which is beneficial to shortening the diffusion path of lithium ions and increasing the diffusion rate of lithium ions.

[0055] Based on the same inventive concept, the present invention also provides an application of the rutile-type TiNbO4 anode material prepared by the above preparation method or the above rutile-type TiNbO4 anode material in the preparation of lithium-ion batteries or sodium-ion batteries.

[0056] Based on the same inventive concept, the present invention also provides a lithium-ion battery or a sodium-ion battery, comprising the rutile-type TiNbO4 anode material prepared by the above preparation method or the above rutile-type TiNbO4 anode material.

[0057] Specifically, the lithium-ion battery or sodium-ion battery of the present invention further includes a positive electrode, an electrolyte, a separator, etc., and these materials are all conventional materials and will not be elaborated here.

[0058] The following further illustrates the rutile-type TiNbO4 anode material of the present application, its preparation method and application with specific examples. This part further illustrates the content of the present invention in combination with specific examples, but should not be construed as a limitation of the present invention. Unless otherwise specified, the technical means adopted in the examples are conventional means well known to those skilled in the art. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art.

[0059] Example 1

[0060] The present application example provides a preparation method of a rutile-type TiNbO4 anode material, comprising the following steps:

[0061] S1. Prepare a two-dimensional layered double transition metal carbide TiNbC MXene precursor, which specifically includes the following steps:

[0062] S11. Mix titanium powder, niobium powder, aluminum powder, and carbon powder in a molar ratio of 1:1:1:1 to obtain a mixture;

[0063] S12. Press the mixture into a block, place it in a high-temperature tube furnace, heat it to 1500 °C at a rate of 5 °C / min under an argon atmosphere, hold for 3 h, then cool, crush, and screen to obtain TiNbAlC;

[0064] S13. Put 2 g of TiNbAlC into a polytetrafluoroethylene liner, add a mixed solution composed of 2 g of lithium fluoride and 40 mL of 0.1 mol / L hydrochloric acid solution as an etchant to obtain a mixed material. Put the mixed material into a reaction kettle, heat it to 90 °C, hold for 12 h, then cool, and obtain a two-dimensional layered double transition metal carbide TiNbC MXene precursor after washing and drying;

[0065] S2. Put 1 g of the two-dimensional layered double transition metal carbide TiNbC MXene precursor prepared in S1 into an alumina crucible, place it in a tube furnace, heat it to 1400 °C at a heating rate of 10 °C / min under an air atmosphere, hold for 4 h; then cool to room temperature to obtain a rutile-type TiNbO4 negative electrode material.

[0066] Example 2

[0067] The embodiment of the present application provides a preparation method of a rutile-type TiNbO4 negative electrode material, including the following steps:

[0068] S1. Prepare a two-dimensional layered double transition metal carbide TiNbC MXene precursor, which specifically includes the following steps:

[0069] S11. Mix titanium powder, niobium powder, aluminum powder, and carbon powder in a molar ratio of 1:1:1.2:1 to obtain a mixture;

[0070] S12. Press the mixture into a block, place it in a high-temperature tube furnace, heat it to 1600 °C at a rate of 5 °C / min under an argon atmosphere, hold for 2 h, then cool, crush, and screen to obtain TiNbAlC;

[0071] S13. Put 2 g of TiNbAlC into a polytetrafluoroethylene liner, add 50 mL of an aqueous solution of ammonium bifluoride with a mass concentration of 10% as an etchant to obtain a mixed material. Put the mixed material into a reaction kettle, heat it to 60 °C, hold for 20 h, then cool, and obtain a two-dimensional layered double transition metal carbide TiNbC MXene precursor after washing and drying;

[0072] S2. Put 1 g of the two-dimensional layered double transition metal carbide TiNbC MXene precursor prepared in S1 into an alumina crucible, place it in a tube furnace, and heat it to 1400 °C at a heating rate of 5 °C / min under a mixed gas of oxygen and argon (the volume ratio of oxygen to argon is 3:7), and keep it at this temperature for 12 h; then cool it to room temperature to obtain the rutile-type TiNbO4 anode material.

[0073] Example 3

[0074] The embodiment of the present application provides a preparation method of a rutile-type TiNbO4 anode material, which includes the following steps:

[0075] S1. Prepare a two-dimensional layered double transition metal carbide TiNbC MXene precursor, which specifically includes the following steps:

[0076] S11. Mix titanium powder, niobium powder, aluminum powder, and carbon powder in a molar ratio of 1:1:1.2:1 to obtain a mixture;

[0077] S12. Press the mixture into a block, place it in a high-temperature tube furnace, heat it to 1400 °C at a rate of 5 °C / min under an argon atmosphere, keep it at this temperature for 12 h, then cool, crush, and sieve it to obtain TiNbAlC;

[0078] S13. Put 2 g of TiNbAlC into a polytetrafluoroethylene inner liner, add a mixed solution composed of 2 g of sodium fluoride and 40 mL of 0.1 mol / L hydrochloric acid solution as an etchant to obtain a mixed material. Put the mixed material into a reaction kettle, heat it to 90 °C, keep it at this temperature for 15 h, then cool it, and obtain the two-dimensional layered double transition metal carbide TiNbC MXene precursor after washing and drying;

[0079] S2. Put 1 g of the two-dimensional layered double transition metal carbide TiNbC MXene precursor prepared in S1 into an alumina crucible, place it in a tube furnace, heat it to 1200 °C at a heating rate of 15 °C / min under an air atmosphere, and keep it at this temperature for 4 h; then cool it to room temperature to obtain the rutile-type TiNbO4 anode material.

[0080] Performance test

[0081] Figure 1 XRD pattern of the rutile-type TiNbO4 anode material prepared in Example 1.

[0082] From Figure 1 It can be seen that the pure rutile phase TiNbO4 can be obtained according to the method in Example 1.

[0083] Figure 2SEM image of the rutile-type TiNbO4 anode material prepared in Example 1.

[0084] From Figure 2 it can be seen that the pure phase of titanium niobate (TiNbNbO4) prepared by the method in Example 1 is stacked in layers.

[0085] The rutile-type TiNbO4 anode material prepared in Example 1 was assembled into a lithium-ion or sodium-ion battery, and its performance was tested as follows:

[0086] The rutile-type TiNbO4 anode material (active material), carbon black (conductive agent), and PVDF (binder) prepared in Example 1 were mixed at a mass ratio of 7:2:1, zirconium beads were added for ball milling, the viscosity was adjusted with NMP, and then the slurry was evenly coated on copper foil with a coater and dried in a vacuum drying oven at 60 °C for 12 h; then the copper foil was cut into electrode discs with a diameter of 12 mm and used as the anode. A lithium metal sheet was used as the counter electrode, and a CR2016-type coin cell was assembled in a glove box protected by high-purity argon; a sodium metal sheet was used as the counter electrode, and a CR2025-type coin cell was assembled in the glove box. The assembled lithium-ion or sodium-ion battery was left standing at room temperature for 24 h and then subjected to electrochemical testing.

[0087] Figure 3 Rate performance graph of the lithium-ion battery assembled with the rutile-type TiNbO4 anode material prepared in Example 1.

[0088] From Figure 3 it can be seen that after being tested at different rates and then restored to 1C, its specific capacity remains at a level comparable to the initial capacity.

[0089] Figure 4 Cycling performance graph of the sodium-ion battery assembled with the rutile-type TiNbO4 anode material prepared in Example 1 at 1C.

[0090] From Figure 4 it can be seen that after 200 cycles, the prepared titanium niobate material still has a high capacity retention rate of 104%. This shows that the present invention provides a new method for the preparation of anode materials for ion batteries (such as sodium-ion batteries), and also provides a new direction for the research of sodium-ion anode materials.

[0091] Figure 5 XRD pattern of the rutile-type TiNbO4 anode material prepared in Example 2.

[0092] From Figure 5 it can be seen that pure rutile-phase TiNbO4 can be obtained by the method of Example 2.

[0093] Figure 6 SEM image of the rutile-type TiNbO4 anode material prepared in Example 2.

[0094] As can be seen from Figure 6 it, according to the method of Example 2, the pure phase of titanium niobate (TiNbNbO4) obtained is stacked in layers.

[0095] Figure 7 XRD pattern of the rutile-type TiNbO4 anode material prepared in Example 3.

[0096] As can be seen from Figure 7 it, the pure rutile phase TiNbO4 can be obtained according to the method of Example 3.

[0097] Figure 8 SEM image of the rutile-type TiNbO4 anode material prepared in Example 3.

[0098] As can be seen from Figure 8 it, according to the method of Example 3, the pure phase of titanium niobate (TiNbNbO4) obtained is stacked in layers.

[0099] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A preparation method of a rutile-type TiNbO4 negative electrode material, characterized in that Including the following steps: Preparing a two-dimensional layered double transition metal carbide TiNbC MXene precursor; Heating the two-dimensional layered double transition metal carbide TiNbC MXene precursor from room temperature to 1200 - 1600 °C at a rate of 0.5 - 20 °C / min and oxidizing for 2 - 10 h to obtain a rutile-type TiNbO4 negative electrode material; The preparation method of the two-dimensional layered double transition metal carbide TiNbC MXene precursor includes the following steps: Mixing titanium powder, niobium powder, aluminum powder, and carbon powder to obtain a mixture; Heating the mixture from room temperature to 1200 - 1600 °C at a rate of 0.5 - 20 °C / min under a protective atmosphere and calcining for 2 - 20 h to obtain TiNbAlC; Adding an etching agent to TiNbAlC, keeping the temperature at 80 - 120 °C for 12 - 36 h, washing, and drying to obtain the two-dimensional layered double transition metal carbide TiNbC MXene precursor; The molar ratio of the titanium powder, niobium powder, aluminum powder, and carbon powder is (1 - 1.2):(1 - 1.2):(1.1 - 1.3):(0.9 - 1.1); The molar ratio of the TiNbAlC to the etching agent is (0.5 - 2):(0.5 - 2); The etching agent includes at least one of lithium fluoride, sodium fluoride, potassium fluoride, ammonium bifluoride, hydrochloric acid, and hydrofluoric acid.

2. The preparation method of the rutile-type TiNbO4 negative electrode material according to claim 1, wherein, The protective atmosphere includes at least one of nitrogen, argon, helium, and neon.

3. The preparation method of the rutile-type TiNbO4 negative electrode material according to claim 1, characterized in that, In the step of oxidizing the two-dimensional layered double transition metal carbide TiNbC MXene precursor at 1200 - 1600 °C for 2 - 10 h, the oxidation atmosphere includes any one of air, oxygen, a mixture of oxygen and argon, and a mixture of oxygen and nitrogen.

4. A rutile-type TiNbO4 anode material, characterized in that, Prepared by using the preparation method according to any one of claims 1 - 3.

5. Application of a rutile-type TiNbO4 negative electrode material prepared by using the preparation method according to any one of claims 1 - 3 or the rutile-type TiNbO4 negative electrode material according to claim 4 in the preparation of a lithium-ion battery or a sodium-ion battery.

6. A lithium-ion battery or a sodium-ion battery, characterized in that, Including a rutile-type TiNbO4 negative electrode material prepared by using the preparation method according to any one of claims 1 - 3 or the rutile-type TiNbO4 negative electrode material according to claim 4.

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