Anion-doped perovskite titanate material as well as preparation method and application thereof

Abstract

The invention provides an anion-doped perovskite type titanate material and a preparation method and application thereof, the structural formula of the anion-doped perovskite type titanate material is AxByTiOzN1-z, A is an alkali metal element, B is a rare earth element, N is an anion element, 0 lt; x is less than or equal to 1, 0lt; y < = 1, 0lt; z < = 4. The prepared anion-doped perovskite type titanate material is applied to a negative electrode of a lithium ion battery, and compared with a traditional perovskite type titanate material, the anion-doped perovskite type titanate material has better fast charging performance and power characteristics, ultra-long cycle life and excellent safety.

Description

Technical Field

[0001] This invention belongs to the field of lithium-ion battery technology, specifically relating to an anion-doped perovskite titanate material, its preparation method, and its application. Background Technology

[0002] Lithium-ion batteries have become the most popular energy storage device due to their high energy density, long cycle life, lack of memory effect, low cost, and environmental friendliness. Over the past decade, they have been widely used in electric vehicles, portable smart devices, and energy storage grids. The negative electrode is one of the key components of the battery. Currently, some lithium-ion batteries use perovskite titanate materials (A... x B y TiO z ) is used as its negative electrode material.

[0003] Perovskite titanate materials (A) x B y TiO z It has a high theoretical specific capacity (>200mAhg) -1 Ideal operating potential (<0.5V vs. Li) + Lithium-ion batteries using perovskite titanate (Li₂ / Li₃) as the negative electrode will possess both high safety and high energy density. However, the perovskite titanate materials currently used as negative electrodes in lithium-ion batteries are semiconductors or insulators with intrinsically low electronic conductivity, hindering rapid electron transport. Furthermore, lithium ions have a low diffusion coefficient and high migration barrier in the crystal structure of perovskite titanate materials, resulting in slow ion insertion and extraction kinetics. This leads to severe electrochemical polarization during high-current charge and discharge, causing a sharp decrease in the actual release capacity, failing to meet the demands of fast charging. Moreover, the capacity retention rate decreases rapidly after multiple charge-discharge cycles.

[0004] Therefore, there is an urgent need to develop a perovskite titanate material with simple processing and low cost to meet its application in fast-charging, long-cycle, and high-rate lithium-ion batteries. Summary of the Invention

[0005] In view of this, the present invention provides an anion-doped perovskite titanate material, its preparation method and application, and the prepared lithium battery has the advantages of fast charging, long cycle life and high rate capability.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides an anion-doped perovskite titanate material with the structural formula A. x B y TiO z N 1-zWhere A is an alkali metal element, B is a rare earth element, N is an anionic element, and 0 <x≤1,0<y≤1,0<z≤4。

[0007] Preferably, element A is at least one of Li, Na, and K; and / or, Element B is at least one of Y, Nd, and Sm; and / or, The nitrogen element is at least one of F and Cl.

[0008] Secondly, the present invention provides a method for preparing the anion-doped perovskite titanate material, comprising the following steps: S1, according to structural formula A x B y TiO z N 1-z The nominal chemical ratios of A-site elements, B-site elements, N elements and Ti elements were used to weigh out the A-source material, B-source material, N-source material and titanium source material, and each source material was fully dispersed. After the material particle size was reduced to the size of primary particles, they were mixed to obtain the precursor. S2. Heat treatment of the precursor under an oxygen-containing atmosphere yields AxByTiOzN1-z anion-doped perovskite titanate material.

[0009] It should be noted that thoroughly dispersing the various source materials and reducing the particle size to the size of primary particles is to further ensure thorough mixing of the raw materials. This feature is particularly suitable for the solid-state preparation of anion-doped perovskite titanate materials. During solid-state mixing, the differences in density, particle size, and specific surface area of ​​the primary particles of various raw materials lead to differences in particle mass, surface energy, and powder energy. This causes smaller particles to spontaneously adsorb onto the surface of larger particles, reducing the total energy and achieving a stable energy state, resulting in a uniform mixture of raw materials. This effectively avoids material stratification and uneven agglomeration. Similarly, under liquid conditions, thoroughly dispersed primary particles of raw materials also promote the uniform mixing of precursors.

[0010] In the technical solution of this application, the use of anion-doped perovskite titanate materials has the following advantages: 1. Optimized lithium storage mechanism and improved reversible capacity: 1) Suppressing irreversible oxygen activation and side reactions; 2) Stabilizing the structure and avoiding harmful phase transitions. 2. Improved ionic conductivity, significantly reducing the activation energy of lithium-ion migration. 3. Enhanced electronic conductivity, greatly improving the intrinsic electronic conductivity of the material. The improvement in electronic conductivity means a reduction in the overall internal resistance of the electrode, higher utilization of active materials, especially under high current, reduced electrode polarization, better voltage plateau maintenance, and more full capacity utilization.

[0011] Preferably, in step S1, the apparatus used to fully disperse the various source materials includes a mixer, air mill, sand mill, ball mill, or air jet mill, and the source materials are further mixed in the absence of liquid to obtain a precursor. It should be noted that these devices can shear powder materials at high speed and disperse them by collision within a short time, ranging from 30 seconds to 2 hours, to achieve uniform dispersion.

[0012] Preferably, in step S1, the specific steps of mixing are as follows: dissolving and mixing source material A, source material B, source material N and titanium source material with solvent to obtain a mixed solution and thus a precursor.

[0013] Preferably, the solvent includes one or more of water, methanol, ethanol, isopropanol, ethylene glycol, glycerol, n-propanol, isobutanol, and n-butanol.

[0014] Preferably, in the mixed solution, the concentration of alkali metal ions is 0.001-15 mol / L; and / or, In the mixed solution, the concentration of rare earth metal ions is 0.001-15 mol / L; and / or, In the mixed solution, the concentration of titanium ions is 0.001-15 mol / L.

[0015] Preferably, source material A includes at least one selected from sodium oxalate, sodium carbonate, sodium bicarbonate, sodium oxide, sodium hydroxide, sodium ethoxide, sodium peroxide, sodium nitrate, sodium sulfate, and sodium acetate; and / or, Titanium source materials include at least one of the following: isopropyl titanate, titanium sulfate, titanium tetrachloride, titanium trichloride, titanium oxysulfate, titanium tetraisopropoxide, titanium tetrabutyl titanate, titanium tetrafluoride, potassium titanium oxalate, and titanium dioxide; and / or, Source material B includes at least one of yttrium oxide, yttrium oxalate, yttrium carbonate hydrate, yttrium nitrate hexahydrate, yttrium sulfate octahydrate, neodymium oxide, neodymium oxalate, neodymium carbonate hydrate, neodymium nitrate hexahydrate, neodymium sulfate octahydrate, samarium oxide, samarium oxalate, samarium carbonate hydrate, samarium nitrate hexahydrate, and samarium sulfate octahydrate; and / or, The N-source material includes at least one of lithium fluoride, sodium fluoride, potassium fluoride, lithium chloride, sodium chloride, potassium chloride, ammonium fluoride, and ammonium chloride.

[0016] Preferably, in step S1, the ratio of rare earth element atoms to titanium atoms is 0.3-1.1; the mass ratio of alkali metal atoms to titanium atoms is 0.3-1.5; the atomic ratio of anionic elements to oxygen elements is 0.01-0.1; and / or, In step S2, the heat treatment temperature is 600-1300℃, the treatment time is 1-80 hours, and the heating rate is 0.5-20℃ per minute. It should be noted that by controlling the treatment temperature and time during the heat treatment process, the particle size and crystallinity of the perovskite titanate material can be adjusted.

[0017] Thirdly, the present invention provides an anion-doped perovskite titanate material, or an anion-doped perovskite titanate material prepared by the above preparation method, for use in the preparation of negative electrode active materials for lithium-ion batteries.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) This invention prepares anion-doped perovskite titanate materials by simple mixing and heat treatment, and the structural formula is A. x B y TiO z N 1-z The process is simple, the performance is excellent, and the cost is low. Furthermore, by adjusting the heat treatment temperature and time according to the preparation method of this invention, the grain size and crystallinity of the material can be effectively controlled, thereby further improving the electrochemical performance of the material.

[0019] (2) The present invention applies the prepared anion-doped perovskite titanate material to the negative electrode of lithium-ion battery. Compared with traditional perovskite titanate materials, this material has better fast charging performance, power characteristics, ultra-long cycle life and excellent safety. Attached Figure Description

[0020] Figure 1 The NaYTiO provided in Embodiment 1 of the present invention 3.95 F 0.1 XRD patterns; Figure 2 The XRD pattern of NaYTiO4 provided in Comparative Example 1 of this invention; Figure 3 The NaYTiO provided in Embodiment 1 of the present invention 3.95 F 0.1 SEM image; Figure 4 This is a SEM image of NaYTiO4 provided in Comparative Example 1 of the present invention; Figure 5 The NaYTiO provided in Embodiment 1 of the present invention 3.95 F 0.1 Ratio performance diagram; Figure 6 This is a rate performance diagram of NaYTiO4 provided in Comparative Example 1 of the present invention; Figure 7The NaYTiO provided in Embodiment 1 of the present invention 3.95 F 0.1 Cyclic performance graph; Figure 8 The diagram shows the cycling performance of NaYTiO4 provided in Comparative Example 1 of this invention. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0022] Example 1 This embodiment provides an anion-doped perovskite titanate material, which is prepared by the following method: (1) Weigh 383g Y(NO3)3·6H2O, 240g Ti(SO4)2, 60g Na2CO3, and 4.2g NaF and use a ball mill at 300rpm to disperse them evenly into primary granules. (2) The obtained primary particulate raw material was then dissolved in 4000 mL of ethanol and stirred thoroughly for 1 h to obtain a mixed solution. The mixed solution was placed in a forced-air drying oven and dried at 60 °C for 12 h to obtain a powder mixture precursor. (3) The obtained powder mixture precursor was placed in a muffle furnace and heated to 1000℃ at a heating rate of 1℃ / min, and held at that temperature for 2 hours. It was then allowed to cool naturally to room temperature to obtain NaYTiO. 3.95 F 0.1 first product; (4) Take the initial product NaYTiO 3.95 F 0.1 The sample was washed three times with deionized water and dried in a forced-air drying oven at 60°C for 6 hours to obtain NaYTiO. 3.95 F 0.1 Material.

[0023] Example 2 This embodiment provides an anion-doped perovskite titanate material, which is prepared by the following method: (1) Weigh 383g Y(NO3)3·6H2O, 240g Ti(SO4)2, 60g Na2CO3, and 5.84g NaCl and disperse them evenly into primary granules using a ball mill at a speed of 300rpm. (2) The obtained primary particulate raw material was then dissolved in 4000 mL of ethanol and stirred thoroughly for 1 h to obtain a mixed solution. The mixed solution was placed in a forced-air drying oven and dried at 60 °C for 12 h to obtain a powder mixture precursor. (3) The obtained powder mixture precursor was placed in a muffle furnace and heated to 1000℃ at a heating rate of 1℃ / min, and held at that temperature for 2 hours. It was then allowed to cool naturally to room temperature to obtain NaYTiO. 3.95 Cl 0.1 first product; (4) Take the initial product NaYTiO 3.95 Cl 0.1 The sample was washed three times with deionized water and then dried in a forced-air drying oven at 60°C for 6 hours to obtain the preferred NaYTiO₂. 3.95 Cl 0.1 Material.

[0024] Example 3 This embodiment provides an anion-doped perovskite titanate material, which is prepared by the following method: (1) Weigh 160g TiO2, 349g Sm2O3, 150g Na2C2O4 and 2.34g NaCl and place them in a planetary ball mill. Ball mill them at 300rpm for 5h to obtain uniformly dispersed primary granular raw materials. Ball mill and mix for 2h to obtain mixed powder. (2) Subsequently, the raw material in the primary granular state was placed in a sand mill and milled at 1000 rpm for 2 hours to obtain a uniformly mixed powder precursor. The precursor was then heated to 900°C in a muffle furnace at a heating rate of 5°C / min and held for 3 hours. After natural cooling to room temperature, the primary product NaSmTiO was obtained. 3.99 Cl 0.02 ; (4) Take the initial product NaSmTiO 3.99 Cl 0.02 The powder material was washed with deionized water and dried in a forced-air drying oven at 60°C for 6 hours to obtain NaSmTiO. 3.99 Cl 0.02 Material.

[0025] Example 4 This embodiment provides an anion-doped perovskite titanate material, which is prepared by the following method: (1) Weigh 420g Nd(NO3)3·6H2O, 240g Ti(SO4)2, 60g Na2CO3, and 16.8g NaF and disperse the above raw materials into a single-particle state by stirring at 5000rpm for 10min in a shear mixer. (2) Dissolve the primary particulate raw material obtained above in 10000 mL of water, and add ammonia water to adjust the pH to 7. After stirring thoroughly, place it in a hydrothermal reactor and hydrothermally react at 240℃ and 10MPa for 1 hour to obtain the precursor. (3) The obtained precursor was placed in a muffle furnace and heated to 600°C at a heating rate of 2°C / min. The temperature was held for 1 hour and then allowed to cool naturally to room temperature to obtain the initial product NaNdTiO. 3.9 F 0.2 ; (4) Take the initial product NaNdTiO 3.9 F 0.2 The powder material was washed with deionized water and dried in a forced-air oven at 60°C for 6 hours to obtain NaNdTiO. 3.9 F 0.2 Material.

[0026] Comparative Example 1 This comparative example provides a perovskite-type titanate material, which is prepared by the following method: (1) Weigh 383g Y(NO3)3·6H2O, 240g Ti(SO4)2, and 60g Na2CO3, and disperse them evenly into primary particles using a ball mill at 300 rpm. (2) The obtained primary particulate raw material was then dissolved in 4000 mL of ethanol and stirred thoroughly for 1 h to obtain a mixed solution. The mixed solution was placed in a forced-air drying oven and dried at 60 °C for 12 h to obtain a powder mixture precursor. (3) The obtained powder mixture precursor was placed in a muffle furnace and heated to 1000°C at a heating rate of 1°C / min. The temperature was held for 2 hours and then cooled naturally to room temperature to obtain the initial product NaYTiO4. (4) The initial NaYTiO4 was washed three times with deionized water and placed in a forced-air drying oven at 60°C for 6 hours to obtain NaYTiO4 material.

[0027] Performance Tests and Results The crystal phase structures of the electrode materials prepared in Example 1 and Comparative Example 1 were characterized by X-ray diffraction and their molecular formulas were determined by analysis.

[0028] The electrode materials prepared in Example 1 and Comparative Example 1 had an active material mass ratio of 80%, a conductive agent mass ratio of 10%, a binder mass ratio of 10%, and an electrode surface loading of 4 mg / cm² during electrochemical testing. 2 The compacted density is 0.9 g / cm³. 3 The test conditions were at room temperature.

[0029] Figure 1 It is the NaYTiO prepared in Example 13.95 F 0.1 The X-ray diffraction pattern. From the figure, we can see that Cl... - The doping does not affect the crystal structure of the material; the X-ray diffraction peaks observed in the sample are all characteristic peaks of NaYTiO4, with no obvious impurity peaks. Furthermore, NaYTiO4… 3.95 F 0.1 The difference in peak intensity ratio between the characteristic diffraction peaks (100) and (311) compared to that of NaYTiO4 originates from the anion F. - The introduction of .

[0030] Figure 2 The XRD pattern of NaYTiO4 prepared in Comparative Example 1 shows that the X-ray diffraction peaks in the sample are all characteristic peaks of NaYTiO4, with no obvious impurity peaks.

[0031] Figure 3 NaYTiO2 prepared in Example 1 of this invention 3.95 F 0.1 The SEM image shows that the sample has a uniform particle size distribution, ranging from 1 to 3 micrometers, with no obvious particle agglomeration and a smooth surface. This is beneficial for reducing the accumulation of by-reaction products during the electrochemical process and improving the electrochemical performance of the material.

[0032] Figure 4 This is a SEM image of NaYTiO4 prepared in Comparative Example 1 of this invention. The image shows that the NaYTiO4 sample has an extremely uneven particle size distribution, very poor particle conductivity, and primary particles agglomerate with each other, with small particles adhering to the surface. The large specific surface area resulting from these small particles will exacerbate the accumulation of side reactions during the electrochemical process, accelerating the degradation of its electrochemical performance.

[0033] Figure 5 NaYTiO2 prepared in Example 1 of this invention 3.95 F 0.1 The rate performance is as follows. The electrode contains 80% active material, 10% conductive agent, and 10% binder by mass, with an electrode surface loading of 4 mg / cm². 2 The compacted density is 1 g / cm³ 3 The figure shows that when NaYTiO 3.95 F 0.1 At a charge / discharge rate of 0.2C, the initial coulombic efficiency reaches 80%, providing a reversible specific capacity of 233 mAh / g. Even when charged / discharged at a current density of 6C, the material still exhibits a reversible specific capacity as high as 122 mAh / g, with a coulombic efficiency approaching 100%, indicating that NaYTiO 3.95 F 0.1 It has good rate capability.

[0034] Figure 6 This describes the rate performance of NaYTiO4 prepared in Comparative Example 1 of this invention. The electrode contains 80% active material, 10% conductive agent, 10% binder, and has an electrode surface loading of 4 mg / cm². 2 The compacted density is 1 g / cm³ 3 As can be seen from the figure, when NaYTiO4 is charged and discharged at 0.2C, the initial coulombic efficiency is only 57%, and the reversible specific capacity is only 202 mAh / g. When the material is charged and discharged at a current density of 6C, its reversible specific capacity is only 81 mAh / g.

[0035] Figure 7 NaYTiO2 prepared in Example 1 of this invention 3.95 F 0.1 The cycle performance of NaYTiO2 can be seen from the figure. 3.95 F 0.1 When cycled at a 1C charge-discharge current, it provides excellent discharge capacity with minimal capacity decay. After 100 cycles at a 1C current density, the material still exhibits a discharge capacity of 184 mAh / g, with a capacity retention of 99%, indicating that NaYTiO₂... 3.95 F 0.1 It has a good cycle life.

[0036] Figure 8 The figure shows the cycling performance of NaYTiO4 prepared in Comparative Example 1 of this invention. As can be seen from the figure, after 100 cycles at a current density of 1C, the discharge capacity of this material is only 114 mAh / g, and the capacity retention is only 69%.

[0037] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An anion-doped perovskite titanate material, characterized in that, The structural formula is A x B y TiO z N 1-z Where A is an alkali metal element, B is a rare earth element, N is an anionic element, and 0 <x≤1,0<y≤1,0<z≤4。 2. The anion-doped perovskite titanate material according to claim 1, characterized in that, Element A is at least one of Li, Na, and K; and / or, Element B is at least one of Y, Nd, and Sm; and / or, The nitrogen element is at least one of F and Cl.

3. The method for preparing anion-doped perovskite titanate materials according to claim 1 or 2, characterized in that, Includes the following steps: S1, according to structural formula A x B y TiO z N 1-z The nominal chemical ratios of A-site elements, B-site elements, N elements and Ti elements were used to weigh out the A-source material, B-source material, N-source material and titanium source material, and each source material was fully dispersed. After the material particle size was reduced to the size of primary particles, they were mixed to obtain the precursor. S2. Heat treatment of the precursor under an oxygen-containing atmosphere yields A. x B y TiO z N 1-z Anion-doped perovskite titanate materials.

4. The preparation method according to claim 3, characterized in that, In step S1, the apparatus used to fully disperse the various source materials includes a mixer, an air mill, a sand mill, a ball mill, or an air jet mill, and the various source materials are further mixed in the absence of liquid to obtain a precursor.

5. The preparation method according to claim 3, characterized in that, In step S1, the specific steps of mixing are as follows: mixing source material A, source material B, source material N and titanium source material with solvent until uniform, and drying the obtained uniform mixture to obtain the precursor.

6. The preparation method according to claim 5, characterized in that, Solvents include one or more of the following: water, methanol, ethanol, isopropanol, ethylene glycol, glycerol, n-propanol, isobutanol, and n-butanol.

7. The preparation method according to claim 5, characterized in that, In the mixed solution, the concentration of alkali metal ions is 0.001-15 mol / L; and / or, In the mixed solution, the concentration of rare earth metal ions is 0.001-15 mol / L; and / or, In the mixed solution, the concentration of titanium ions is 0.001-15 mol / L.

8. The preparation method according to claim 3, characterized in that, Source material A includes at least one of sodium oxalate, sodium carbonate, sodium bicarbonate, sodium oxide, sodium hydroxide, sodium ethoxide, sodium peroxide, sodium nitrate, sodium sulfate, and sodium acetate; and / or, Titanium source materials include at least one of the following: isopropyl titanate, titanium sulfate, titanium tetrachloride, titanium trichloride, titanium oxysulfate, titanium tetraisopropoxide, titanium tetrabutyl titanate, titanium tetrafluoride, potassium titanium oxalate, and titanium dioxide; and / or, Source material B includes at least one of yttrium oxide, yttrium oxalate, yttrium carbonate hydrate, yttrium nitrate hexahydrate, yttrium sulfate octahydrate, neodymium oxide, neodymium oxalate, neodymium carbonate hydrate, neodymium nitrate hexahydrate, neodymium sulfate octahydrate, samarium oxide, samarium oxalate, samarium carbonate hydrate, samarium nitrate hexahydrate, and samarium sulfate octahydrate; and / or, The N-source material includes at least one of lithium fluoride, sodium fluoride, potassium fluoride, lithium chloride, sodium chloride, potassium chloride, ammonium fluoride, and ammonium chloride.

9. The preparation method according to claim 3, characterized in that, In step S1, the ratio of rare earth element atoms to titanium atoms is 0.3-1.1; the mass ratio of alkali metal atoms to titanium atoms is 0.3-1.5; the atomic ratio of anionic elements to oxygen elements is 0.01-0.1; and / or, In step S2, the heat treatment temperature is 600-1300℃, the treatment time is 1-80 hours, and the heating rate is 0.5-20℃ per minute.

10. The anion-doped perovskite titanate material according to claim 1 or 2, or the anion-doped perovskite titanate material prepared by the preparation method according to any one of claims 3-9, is used in the preparation of negative electrode active materials for lithium-ion batteries.

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