Niobium-based negative electrode material and preparation method thereof

Abstract

The invention provides a niobium-based negative electrode material and a preparation method thereof, and the preparation method comprises the following steps: S1, dissolving and mixing a chromium source, a zinc source, a titanium source, an aluminum source, a niobium source and citric acid to obtain mixed slurry; s2, drying the mixed slurry to obtain dried mixed material powder; and S3, calcining the mixed material powder to obtain the niobium-based negative electrode material. In the preparation process of the niobium-based negative electrode material, various transition metals such as a chromium source, a zinc source, a titanium source and an aluminum source are introduced at the same time, and due to the fact that different transition metal ions have different valence states and electronic structures, the introduction of the various transition metals can provide additional electronic channels and ion diffusion paths, and the performance of the niobium-based negative electrode material is improved. Therefore, the electronic and ionic conductivity of the niobium-based negative electrode material is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of battery materials, and in particular to a niobium-based negative electrode material and a preparation method thereof. Background Art

[0002] Lithium-ion batteries are the core energy storage devices of modern mobile electronic devices and electric vehicles. Their performance directly affects the endurance, safety, and service life of these devices. Among the many components of lithium-ion batteries, the selection and optimization of anode materials are crucial to improving the overall performance of the battery.

[0003] Currently, graphite is the most commonly used negative electrode material for lithium-ion batteries, with a theoretical charge capacity of up to 372 mAh / g, which provides significant advantages in terms of energy density. However, graphite's low lithium insertion potential limits its potential for high-energy-density battery applications. This is especially true during rapid charge and discharge processes and under high and low temperature operating conditions, where graphite negative electrode materials are prone to the formation of lithium dendrites. The formation of lithium dendrites not only reduces the battery's cycle efficiency but can also cause internal short circuits, leading to battery safety issues.

[0004] In order to overcome the limitations of graphite negative electrode materials, researchers have turned to other types of negative electrode materials, such as lithium titanate (LTO), which has attracted much attention for its stable lithium insertion and removal performance and good high and low temperature adaptability. However, the theoretical charge capacity of lithium titanate is relatively low, only 175mAh / g, which limits the improvement of battery energy density. In recent years, niobium-based negative electrode materials have become a research hotspot due to their high theoretical charge capacity (387-403mAh / g) and moderate lithium insertion potential (1.6-1.7V), especially TiNb2O7 and Ti2Nb 10 O 29 Niobium titanium oxide materials, such as niobium-titanium oxide, not only have high theoretical charge capacity, but also their unique structure in the monoclinic C2 / m space group facilitates rapid lithium ion intercalation and deintercalation, exhibiting excellent electrochemical performance. However, niobium-based negative electrode materials still have the problem of low electronic conductivity. This is because niobium-based materials have a wide band gap energy (Eg>2eV), resulting in low inherent electronic and ionic conductivity, which in turn affects the performance of lithium-ion batteries under high rate and extreme temperature conditions. Summary of the Invention

[0005] The main purpose of the present invention is to provide a niobium-based negative electrode material and a preparation method thereof, so as to solve the technical problem of low electronic conductivity of niobium-based negative electrode materials in the prior art.

[0006] To achieve the above objectives, according to one aspect of the present invention, a method for preparing a niobium-based negative electrode material is provided, comprising: step S1, dissolving and mixing a chromium source, a zinc source, a titanium source, an aluminum source, a niobium source, and citric acid to obtain a mixed slurry; step S2, drying the mixed slurry to obtain a dried mixed material powder; and step S3, calcining the mixed material powder to obtain a niobium-based negative electrode material.

[0007] Furthermore, before step S2, the preparation method further comprises: ball milling the mixed slurry in deionized water.

[0008] Furthermore, in step S1, the ratio of the chromium source, the zinc source, the titanium source, the aluminum source and the niobium source is 1 / 3:1 / 6:1 / 6:1 / 3:11 in molar parts.

[0009] Furthermore, in step S1, the chromium source is preferably Cr2O3, the zinc source is preferably Zn(NO3)·6H2O, the titanium source is preferably Ti(OH)4, the niobium source is preferably Nb2O5, and the aluminum source is preferably Al2O3.

[0010] Furthermore, in step S1, the chromium source, zinc source, titanium source, niobium source, aluminum source and citric acid are dissolved and mixed, including: adding citric acid to deionized water to obtain a citric acid aqueous solution; adding a niobium source to the citric acid aqueous solution and stirring to obtain a premix; adding a chromium source, zinc source, titanium source and aluminum source to the premix and stirring to obtain a mixed slurry.

[0011] Furthermore, in step S2, the drying is spray drying, and preferably the inlet temperature of the spray drying is 250-270°C, and the outlet temperature is 100-120°C.

[0012] Furthermore, in step S3, the calcination temperature is 900-1100° C., and the calcination time is 3-6 hours.

[0013] According to another aspect of the present invention, a niobium-based negative electrode material is provided. The niobium-based negative electrode material is prepared using the above-mentioned preparation method.

[0014] Furthermore, the specific surface area of the niobium-based negative electrode material is 3 to 4 m 2 / g.

[0015] Furthermore, the first discharge capacity of the niobium-based negative electrode material is 243 mAh / g, and the first charge capacity of the niobium-based negative electrode material is 234.9 mAh / g.

[0016] By applying the technical solution of the present invention, the niobium-based negative electrode material has a high theoretical charge capacity and a moderate lithium insertion potential, which can ensure the stable storage and release of lithium ions during the charge and discharge process, reduce the byproducts of the electrochemical reaction, and improve the cycle efficiency and battery life. However, the niobium-based negative electrode material still has the problem of low electronic conductivity. In the process of preparing the niobium-based negative electrode material, the present application simultaneously introduces multiple transition metals such as chromium source, zinc source, titanium source and aluminum source. Since different transition metal ions have different valence states and electronic structures, the introduction of multiple transition metals can provide additional electron channels and ion diffusion paths, thereby improving the electronic and ionic conductivity of the niobium-based negative electrode material; during the charge and discharge process, the insertion and deinsertion of lithium ions will cause the volume of the material to expand and contract. A single niobium-based material may be unable to withstand such repeated stress changes, resulting in phase change and structural damage. The doping of multiphase metal ions can enhance the structural flexibility of the material, reduce the phase change during the charge and discharge process, and improve the stability of the niobium-based negative electrode material during the charge and discharge process. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The accompanying drawings, which constitute part of this application, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0018] Figure 1 A comparison diagram of the XRD spectrum of Example 1 of the present invention and the XRD spectrum of Comparative Example 1 is shown. DETAILED DESCRIPTION

[0019] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments in this application can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0020] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0021] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that the terms used in this way are interchangeable where appropriate, so that the embodiments of the present application described herein can, for example, be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0022] Now, exemplary embodiments according to the present application will be described in more detail with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in a variety of different forms and should not be interpreted as being limited to the embodiments described herein. It should be understood that these embodiments are provided to make the disclosure of this application thorough and complete, and to fully convey the concepts of these exemplary embodiments to those of ordinary skill in the art. In the accompanying drawings, for the sake of clarity, the thickness of layers and regions may be exaggerated, and the same reference numerals are used to represent the same devices, and thus their descriptions will be omitted.

[0023] As analyzed in the background, existing niobium-based anode materials have wide band gap energies, resulting in inherently low electronic and ionic conductivity. This, in turn, affects the performance of lithium-ion batteries at high rates and extreme temperatures. In other words, niobium-based anode materials still suffer from low electronic conductivity. To address this technical problem, the present invention provides a niobium-based anode material and a method for preparing the same.

[0024] In a typical embodiment of the present application, a method for preparing a niobium-based negative electrode material is provided, such as Figure 1 As shown, the specific steps include:

[0025] Step S1: dissolving and mixing a chromium source, a zinc source, a titanium source, an aluminum source, a niobium source and citric acid to obtain a mixed slurry.

[0026] Step S2: Dry the mixed slurry to obtain dried mixed material powder.

[0027] Step S3: calcining the mixed material powder to obtain a niobium-based negative electrode material.

[0028] Niobium-based negative electrode materials have a high theoretical charge capacity and a moderate lithium insertion potential, which can ensure the stable storage and release of lithium ions during the charge and discharge process, reduce the byproducts of the electrochemical reaction, and improve the cycle efficiency and battery life. However, niobium-based negative electrode materials still have the problem of low electronic conductivity. In the process of preparing niobium-based negative electrode materials, the present application simultaneously introduces multiple transition metals such as chromium source, zinc source, titanium source and aluminum source. Since different transition metal ions have different valence states and electronic structures, the introduction of multiple transition metals can provide additional electron channels and ion diffusion paths, thereby improving the electronic and ionic conductivity of niobium-based negative electrode materials. During the charge and discharge process, the insertion and deinsertion of lithium ions will cause the volume of the material to expand and contract. A single niobium-based material may be unable to withstand such repeated stress changes, resulting in phase change and structural damage. The doping of multiphase metal ions can enhance the structural flexibility of the material, reduce the phase change during the charge and discharge process, and improve the stability of the niobium-based negative electrode material during the charge and discharge process.

[0029] It can be understood that in step S1, citric acid acts as an effective complexing agent to form a stable coordination compound with the metal ions, thereby uniformly dispersing the metal ions in the mixed slurry, preventing the metal ions from precipitating or agglomerating prematurely, and ensuring that the metal ions can be uniformly embedded in the negative electrode material during the subsequent drying and calcination process, thereby improving the uniformity of doping and the performance of the material. At the same time, citric acid can control the reaction rate during the material synthesis process by regulating the activity of the metal ions, avoiding the unevenness and instability caused by rapid reactions, and helping to form a more ordered and pure crystal structure.

[0030] It can be understood that in step S2, the mixed slurry is dried to form fine and uniform particles, which is conducive to the uniform embedding of metal ions and densification of the material during the subsequent calcination process, and further enhances the structural stability and metal ion transport performance of the material.

[0031] In one embodiment of the present application, before step S2, the preparation method further includes: ball milling the mixed slurry in deionized water.

[0032] Ball milling is a mechanochemical method that uses high-speed rotating balls to grind and collide the solid particles in the slurry, which can promote the uniform mixing of the various metal sources and citric acid. The grinding process in the ball milling process can significantly reduce the particle size of the solid raw material and increase the specific surface area of the particles. This not only helps to improve the reactivity of the material, but also improves the diffusion rate of lithium ions in the material, thereby improving the electrochemical properties of the battery material, such as charge and discharge rate and cycle stability. During the ball milling process, citric acid acts as a chelating agent and more easily forms stable complexes with metal ions under the action of mechanical force. These complexes can ensure that the metal ions can be evenly embedded in the lattice of the niobium-based material in the subsequent synthesis steps, avoiding the formation of independent impurity phases and improving the purity of the material.

[0033] In one embodiment of the present application, in step S1, the ratio of the chromium source, the zinc source, the titanium source, the aluminum source and the niobium source is 1 / 3:1 / 6:1 / 6:1 / 3:11 in molar parts.

[0034] Preferably, in step S1, the chromium source is preferably Cr2O3, the zinc source is preferably Zn(NO3)·6H2O, the titanium source is preferably Ti(OH)4, the niobium source is preferably Nb2O5, and the aluminum source is preferably Al2O3.

[0035] In one embodiment of the present application, step S1 of dissolving and mixing the chromium source, zinc source, titanium source, niobium source, aluminum source, and citric acid comprises the following steps:

[0036] Step S11: adding citric acid to deionized water to obtain a citric acid aqueous solution.

[0037] Dissolving citric acid first provides a suitable environment for the subsequent addition of metal sources. After the metal ions are complexed with citric acid, premature precipitation of the metal ions can be avoided, which helps to achieve more uniform ion doping in the subsequent steps.

[0038] Step S12: adding a niobium source to the citric acid aqueous solution and stirring the mixture to obtain a premix.

[0039] Compared with other metal sources, niobium sources account for the largest proportion and are preferably mixed to avoid the precipitation of niobium ions.

[0040] Step S13: adding a chromium source, a zinc source, a titanium source and an aluminum source to the premix and stirring the mixture to obtain a mixed slurry.

[0041] In one embodiment of the present application, in step S2, the drying is spray drying, and preferably the inlet temperature of the spray drying is 250-270°C, and the outlet temperature is 100-120°C.

[0042] Spray drying is used to dry the mixed slurry, which helps to form particles with good fluidity and uniform composition, providing an ideal precursor material for the subsequent calcination process, thereby improving the structural stability and electrochemical performance of the final material.

[0043] In one embodiment of the present application, in step S3, the calcination temperature is 900-1100° C., and the calcination time is 3-6 hours.

[0044] Controlling the calcination temperature and time within the above range can ensure that the material has ideal structure and properties to meet the needs of high-performance lithium-ion batteries.

[0045] In another typical embodiment of the present application, a niobium-based negative electrode material is provided. The niobium-based negative electrode material is prepared using the preparation method in the above embodiment.

[0046] Preferably, the specific surface area of the niobium-based negative electrode material is 3 to 4 m 2 / g.

[0047] Preferably, the first discharge capacity of the niobium-based negative electrode material is 243 mAh / g, and the first charge capacity of the niobium-based negative electrode material is 234.9 mAh / g.

[0048] It is understood that in the field of battery technology, initial discharge capacity specifically refers to the discharge capacity of a battery during its first complete charge-discharge cycle. It is an important indicator of the electrochemical performance of a battery material or battery system, reflecting the amount of charge the material can store and release during initial use. Initial charge capacity specifically refers to the amount of lithium ion charge that can be embedded per unit mass of the negative electrode material during the battery's first charge cycle. It reflects the negative electrode material's ability to store lithium ions during initial charge, i.e., the battery's initial use.

[0049] The measurement process of the first discharge capacity is as follows:

[0050] 1. First, the battery materials are made into electrodes and assembled into batteries.

[0051] 2. Then, charge the battery for the first time until it reaches the specified potential or charge capacity.

[0052] 3. Next, perform the first discharge until the battery voltage drops to the discharge cut-off voltage.

[0053] 4. During the discharge process, record the discharge current and time, and calculate the total amount of electricity released during the discharge process, that is, the first discharge capacity.

[0054] 5. The first discharge capacity is often compared with the first charge capacity to calculate the first coulombic efficiency, which can reflect the irreversible capacity loss of the material during the first charge and discharge process.

[0055] The beneficial effects of the present application will be described below with reference to specific embodiments and comparative examples.

[0056] Example 1

[0057] 1800 g of deionized water was weighed and added to a stirring tank, and 28 g of citric acid was weighed and added to the stirring tank, and the mixture was stirred at a stirring speed of 500 rpm.

[0058] After the citric acid is dissolved, add 266g of Nb2O5 and stir for 30 minutes.

[0059] 3.091 g of Al2O3, 2.82 g of Ti(OH)4, 4.61 g of Cr2O3, and 9.015 g of Zn(NO3)·6H2O were added to a stirring tank and stirred for 18 h.

[0060] The uniformly stirred slurry was added to the ball mill, and the mixing tank was rinsed with 230 mL of deionized water. The ball mill speed was set to 3000 rpm, and the ball mill was started until the cumulative power consumption of the ball mill reached 6 kWh.

[0061] The ball-milled material was transferred to a mixing tank for use in the spray drying process. The spray drying inlet temperature was adjusted to 260°C ± 3°C, the outlet temperature to 106°C ~ 111°C, the pressure to 0.30 MPa, and the air flow rate to 8.0 m 3 / h, and feed the material after the outlet temperature stabilizes, with a feed speed of 15-17rpm.

[0062] The spray-dried material was calcined at a temperature of 1000° C., a holding time of 4 h, and a heating rate of 5° C. / min. After calcination, it was naturally cooled to obtain a doped oxide powder, wherein the obtained oxide powder was named ANO-10-1000-4.

[0063] Comparative Example 1

[0064] 1800 g of deionized water was weighed and added to a stirring tank, and 27.3 g of citric acid was weighed and added to the stirring tank, and the mixture was stirred at a stirring speed of 500 rpm.

[0065] After the citric acid is dissolved, add 266g of Nb2O5 and stir for 30 minutes.

[0066] 9.3 g of Al2O3 was added to the stirred tank and stirred for 18 h.

[0067] The uniformly stirred slurry was added to the ball mill, and the mixing tank was rinsed with 230 mL of deionized water. The ball mill speed was set to 3000 rpm, and the ball mill was started until the cumulative power consumption of the ball mill reached 6 kWh.

[0068] The ball-milled material was transferred to a mixing tank for use in the spray drying process. The spray drying inlet temperature was adjusted to 260°C ± 3°C, the outlet temperature to 106°C ~ 111°C, the pressure to 0.30 MPa, and the air flow rate to 8.0 m 3 / h, and feed the material after the outlet temperature stabilizes, with a feed speed of 15-17rpm.

[0069] The spray-dried material was calcined at a temperature of 1000° C., a holding time of 4 h, and a heating rate of 5° C. / min. After calcination, it was naturally cooled to obtain a doped oxide powder, wherein the obtained oxide powder was named D-ANO-11-1000-4.

[0070] The oxide powder ANO-10-1000-4 obtained in Example 1 and the oxide powder D-ANO-11-1000-4 obtained in Comparative Example 1 were analyzed using XRD spectra.

[0071] like Figure 1 As shown in the figure, in an XRD spectrum, the horizontal axis usually represents the 2θ value (twice the scattering angle), and the vertical axis represents the diffraction intensity (Intensity), which can be in arbitrary units (arb. units) and represents relative intensity. Each peak (or diffraction peak) in the spectrum corresponds to the diffraction of a specific crystal plane within the material. The position of the peak (2θ value) is related to the interplanar spacing (d value), while the peak intensity is related to the type, number, and arrangement of atoms in the lattice. By analyzing the XRD spectrum, it is possible to identify the crystalline phases present in the material, determine the lattice parameters, and evaluate the orientation, size, and microstrain of the crystal.

[0072] from Figure 1 It can be seen that the XRD spectrum of ANO-10-1000-4 is above the XRD spectrum of D-ANO-11-1000-4, and the peak lines of the XRD spectrum of ANO-10-1000-4 are consistent with those of the XRD spectrum of D-ANO-11-1000-4, indicating that the structure of the material is not changed after doping, and the peak intensity after doping is stronger than that of the pure phase, indicating better crystallinity.

[0073] The particle size and specific surface area of the oxide powder ANO-10-1000-4 obtained in Example 1 and the oxide powder D-ANO-11-1000-4 obtained in Comparative Example 1 were measured, and the test results are listed in Table 1.

[0074] Table 1

[0075]

[0076] As can be seen from Table 1, the particle size difference between the pure phase material and the doped material is small, indicating that the doping process has little effect on the particle size of the material, indicating that the doping process can well maintain the original particle size distribution of the material. Particle size control is crucial for the electrochemical performance of battery materials, because a smaller particle size helps shorten the diffusion path of lithium ions, improves the material's conductivity and reaction rate, and thus improves the battery's charge and discharge efficiency and cycle stability. The specific surface area of the doped material is larger than that of the pure phase material. The increase in specific surface area is conducive to increasing the contact area between the material and the electrolyte, promoting the rapid diffusion and embedding of lithium ions, and thus improving the electrochemical performance of the battery. At the same time, a larger specific surface area may also mean an increase in the material's active sites, which helps to improve the material's lithium storage capacity.

[0077] The oxide powders ANO-10-1000-4 obtained in Example 1 and D-ANO-11-1000-4 obtained in Comparative Example 1 were fabricated into negative electrode sheets. These sheets were then assembled with the positive electrode, electrolyte, and other components to form complete lithium-ion batteries. The batteries were subjected to charge and discharge tests at a current rate of 0.1 C over a voltage range of 1.0 V to 3.0 V. The test results are listed in Table 2.

[0078] The battery is charged for the first time to a state where lithium ions are fully embedded (or charged to a specific cutoff potential). The voltage change and total charge passing through the battery during the charging process are monitored and recorded, which is the initial charge capacity. The charge capacity reflects how much lithium ions the negative electrode material can store in the charged state, that is, the material's electrochemical activity and lithium ion embedding ability.

[0079] The battery is discharged for the first time until all lithium ions are deintercalated or the preset discharge cutoff potential is reached. By measuring the battery's output current and discharge time, the total amount of electricity released during the entire discharge process can be calculated, which is the initial discharge capacity. A higher initial discharge capacity indicates that the material has a higher lithium storage capacity and can provide more energy output.

[0080] The ratio of the first charge capacity to the first discharge capacity is the first coulombic efficiency. A higher first coulombic efficiency means that the insertion and deinsertion process of lithium ions is reversible and the battery's cycle performance is better.

[0081] The discharge capacity after 50 cycles is tested. This parameter is an important indicator for evaluating the cycle stability and life performance of battery materials.

[0082] Table 2

[0083]

[0084] It can be seen from Table 2 that after the material is modified by multi-phase ion doping, the first discharge and first charge specific capacities of the material are slightly improved, and the capacity retention rate after modification is much higher than that of the pure phase material.

[0085] From the above description, it can be seen that the above embodiments of the present invention achieve the following technical effects:

[0086] Niobium-based negative electrode materials have a high theoretical charge capacity and a moderate lithium insertion potential, which can ensure the stable storage and release of lithium ions during the charge and discharge process, reduce the byproducts of the electrochemical reaction, and improve the cycle efficiency and battery life. However, niobium-based negative electrode materials still have the problem of low electronic conductivity. In the process of preparing niobium-based negative electrode materials, the present application simultaneously introduces multiple transition metals such as chromium source, zinc source, titanium source and aluminum source. Since different transition metal ions have different valence states and electronic structures, the introduction of multiple transition metals can provide additional electron channels and ion diffusion paths, thereby improving the electronic and ionic conductivity of niobium-based negative electrode materials. During the charge and discharge process, the insertion and deinsertion of lithium ions will cause the volume of the material to expand and contract. A single niobium-based material may be unable to withstand such repeated stress changes, resulting in phase change and structural damage. The doping of multiphase metal ions can enhance the structural flexibility of the material, reduce the phase change during the charge and discharge process, and improve the stability of the niobium-based negative electrode material during the charge and discharge process.

[0087] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used herein to describe the spatial positional relationship of a device or feature to other devices or features as shown in the figures. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figures. For example, if the device in the drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0088] In addition to the above, it should be noted that references to "one embodiment," "another embodiment," "an embodiment," and the like in this specification refer to specific features, structures, or characteristics described in conjunction with that embodiment as included in at least one embodiment generally described in this application. The appearance of the same expression in multiple places in the specification does not necessarily refer to the same embodiment. Furthermore, when a specific feature, structure, or characteristic is described in conjunction with any embodiment, it is intended that such feature, structure, or characteristic, when implemented in conjunction with other embodiments, also falls within the scope of the present invention.

[0089] In the above embodiments, the description of each embodiment has its own focus. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0090] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A method for preparing a niobium-based negative electrode material, characterized in that: include: Step S1, dissolving and mixing a chromium source, a zinc source, a titanium source, an aluminum source, a niobium source, and citric acid to obtain a mixed slurry; Step S2, drying the mixed slurry to obtain a dried mixed material powder; Step S3: calcining the mixed material powder to obtain a niobium-based negative electrode material.

2. The preparation method according to claim 1, characterized in that Before step S2, the preparation method further includes: The mixed slurry is ball-milled in deionized water.

3. The preparation method according to claim 1, characterized in that In step S1, the ratio of the chromium source, the zinc source, the titanium source, the aluminum source and the niobium source is 1 / 3:1 / 6:1 / 6:1 / 3:11 in parts by mole.

4. The preparation method according to claim 1, characterized in that In step S1, the chromium source is preferably Cr2O3, the zinc source is preferably Zn(NO3)·6H2O, the titanium source is preferably Ti(OH)4, the niobium source is preferably Nb2O5, and the aluminum source is preferably Al2O3.

5. The preparation method according to claim 1, characterized in that In step S1, the chromium source, zinc source, titanium source, niobium source, aluminum source and citric acid are dissolved and mixed, comprising: adding the citric acid to deionized water to obtain a citric acid aqueous solution; adding the niobium source to the citric acid aqueous solution and stirring to obtain a premix; The chromium source, the zinc source, the titanium source and the aluminum source are added to the premix and stirred to obtain the mixed slurry.

6. The preparation method according to claim 1, characterized in that In step S2, the drying is spray drying, and preferably the inlet temperature of the spray drying is 250-270°C, and the outlet temperature is 100-120°C.

7. The preparation method according to claim 1, characterized in that In the step S3, the calcination temperature is 900-1100° C., and the calcination time is 3-6 hours.

8. A niobium-based negative electrode material, characterized in that: The niobium-based negative electrode material is prepared by the preparation method according to any one of claims 1 to 7.

9. The niobium-based negative electrode material according to claim 8, characterized in that: The specific surface area of the niobium-based negative electrode material is 3 to 4 m 2 / g.

10. The niobium-based negative electrode material according to claim 8, characterized in that: The first discharge capacity of the niobium-based negative electrode material is 243 mAh / g, and the first charge capacity of the niobium-based negative electrode material is 234.9 mAh / g.

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