A perovskite heterostructure material, a preparation method, application and battery thereof

Abstract

The application discloses a perovskite heterostructure material, a preparation method and application thereof, and a battery. (n+1) / 2 A' (n+1) / 2 B n O 3n+1 , n = 1, 2, 3; and a chemical formula of the heterostructure coating layer is A 3y A' 2 / 3‑y BO 3‑δ , 0.1 <= y <= 0.2; A is one or more of Li, Na and K, A' is a lanthanide element and / or Y, and B is Ti. The perovskite heterostructure material prepared by the method has intrinsic safe working voltage and excellent high-rate performance and cycle stability, and the preparation method is simple and efficient, and is easy to realize industrialized preparation.

Description

Technical Field

[0001] This invention specifically relates to a perovskite heterostructure material, its preparation method, applications, and batteries. Background Technology

[0002] With the rapid development of electronic devices and electric vehicles, the market demand for lithium-ion battery power density continues to rise, aiming to effectively alleviate battery anxiety through fast charging technology. In lithium-ion battery systems, the negative electrode constitutes a key bottleneck for achieving fast charging. Currently, graphite is the most mature negative electrode material in lithium-ion battery systems, and it is widely used in commercial lithium-ion batteries. However, graphite negative electrodes have specific limitations in terms of power density and safety. Although graphite has a high theoretical specific capacity of 372 mAh / g, its voltage plateau is approximately 0.1V, close to the lithium deposition potential, making it prone to lithium deposition under high-power charge and discharge conditions, thus accelerating battery performance degradation and inducing safety issues. Furthermore, the lithium-ion diffusion coefficient of graphite negative electrodes is relatively low, making it difficult to meet the lithium-ion migration rate requirements during fast charging and discharging, resulting in low charging efficiency. Spinel-type lithium titanate Li4Ti5O 12 Lithium titanate (LTi) is a promising high-power anode material, exhibiting a high ion diffusion coefficient and "zero strain" characteristics during lithium insertion / extraction, resulting in excellent rate performance and long-cycle stability. LTi has a charge / discharge plateau of approximately 1.55V, which provides extremely high safety during fast charging of the entire battery. However, LTi's relatively low theoretical specific capacity (~175mAh / g) and excessively high voltage plateau significantly limit the output energy density of the entire battery. Therefore, developing anode materials with a low voltage plateau, high capacity, and fast charge / discharge capability is of great significance for promoting the development of intrinsically safe lithium-ion batteries and achieving an effective trade-off between energy density and power density.

[0003] Layered perovskite oxides are a novel class of anode materials. These materials possess a relatively low intrinsic voltage plateau, significantly higher than the lithium deposition potential, thus exhibiting excellent intrinsic safety and effectively avoiding safety hazards such as lithium deposition at high rates due to extremely low voltage. However, these materials face numerous challenges, such as insufficient lithium-ion diffusion coefficients, structural framework damage during lithium insertion, and severe performance degradation caused by side reactions between the material surface and the electrolyte. These limitations restrict high-rate performance and long-cycle stability, hindering their development and market application. Currently, there is a lack of simple and effective modification methods for these materials. Therefore, proposing solutions to these problems is crucial to fully unlocking their market potential. Summary of the Invention

[0004] The technical problem solved by this invention is to overcome the shortcomings of existing layered perovskite oxides in terms of poor high-rate performance and long-cycle stability, and to provide a perovskite heterostructure material, its preparation method, applications, and batteries. The perovskite heterostructure material prepared by this invention possesses an intrinsically safe operating voltage and excellent high-rate performance and cycle stability, making it precisely meet the market requirements for high-power fast-charging lithium-ion batteries. It has broad application prospects and significant commercial value in the field of lithium-ion battery technology; moreover, the preparation method is simple and efficient, and easy to industrialize.

[0005] This invention uses layered perovskite A (n+1) / 2 A' (n+1) / 2 B n O 3n+1 As a precursor, during acid etching, hydrogen ions in the acid undergo ion exchange reactions with the layered perovskite oxide cathode surface, regulating the stoichiometric ratio of surface A (e.g., Li), A' (e.g., La), and B (Ti), thereby selectively dissolving A. (n+1) / 2 A' (n+1) / 2 B n O 3n+1 In the shallow layer, some A and A' ions undergo structural reconstruction during subsequent high-temperature annealing, forming a uniform fast ion conductor, A, in situ. 3y A' 2 / 3-y BO 3-δ It possesses abundant oxygen vacancies, providing fast ion / electron transport channels, while the bulk phase remains a layered perovskite structure, thus yielding a novel anode material A with a heterostructure. (n+1) / 2 A' (n+1) / 2 B n O 3n+1 @A 3y A' 2 / 3-y BO 3-δ Because the outer reconstructed layer is formed in situ, the inner and outer lattices of the heterostructure are coherent, and no clear boundary appears. A uniform oxygen-deficient fast ion conductor A is formed on the surface. 3y A' 2 / 3-y BO 3-δ The phase has a three-dimensional lithium diffusion path, which can provide a fast ion and electron transport channel, especially at high discharge rates, reducing A. (n+1) / 2 A' (n+1) / 2 B n O 3n+1 The charge transport limitation improves rate performance. Furthermore, A 3y A' 2 / 3-y BO 3-δThe rigid structure effectively alleviates the mechanical stress caused by the expansion and contraction of the electrode volume, suppresses interfacial side reactions, and helps delay capacity decay; the bulk phase still maintains a layered perovskite phase. This method introduces a highly ionicly conductive and structurally stable uniformly oxygen-deficient A on the particle surface in situ. 3y A' 2 / 3-y BO 3-δ The coating layer significantly improved A (n+1) / 2 A' (n+1) / 2B n O 3n+1 The ion diffusion rate and structural stability during lithium insertion / extraction processes significantly improve battery power density and cycle life.

[0006] The present invention solves the above-mentioned technical problems through the following technical solutions:

[0007] This invention provides a perovskite-type heterostructure material, comprising an alkali metal-containing layered perovskite oxide and a heterostructure coating layer on its surface, with coherent inner and outer lattices and no obvious interface;

[0008] The chemical formula of the alkali metal-containing layered perovskite oxide is A. (n+1) / 2 A' (n+1) / 2 B n O 3n+1 n = 1, 2, 3, corresponding to single-layer, double-layer, and triple-layer structures, respectively; the chemical formula of the heterostructure coating layer is A. 3y A' 2 / 3-y BO 3-δ , 0.1≤y≤0.2; A is one or more of Li, Na and K, A' is a lanthanide rare earth element and / or Y, and B is Ti.

[0009] In this invention, the charge / discharge voltage plateau of the perovskite heterostructure material is preferably 0.4-0.8V, for example 0.6V.

[0010] In this invention, in the chemical formula of the heterostructure coating layer, δ generally refers to the oxygen imbalance caused by the surface structure reconstruction during the annealing process.

[0011] In this invention, the lanthanide rare earth elements are preferably one or more selected from La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu.

[0012] In this invention, the chemical formula of the heterostructure coating layer preferably has 0.1 ≤ y ≤ 0.17, for example 0.11, 0.15 or 0.17.

[0013] In this invention, the thickness of the heterostructure coating layer can be 2 to 10 nm.

[0014] This invention also provides a method for preparing a perovskite-type heterostructure material, comprising the following steps:

[0015] The perovskite-type heterostructure material is prepared by calcining a mixture of alkali metal-containing layered perovskite oxide and acid solution after an ion exchange reaction at 20-160℃.

[0016] In this invention, the acid solution is preferably one or more selected from hydrochloric acid, nitric acid, citric acid, acetic acid, formic acid, propionic acid, benzoic acid, and ethylenediaminetetraacetic acid. The solvent in the acid solution can be conventional in the art, such as deionized water. The concentration of the acid solution can be 0.1-2.0M, preferably 0.2-1.5M, for example 0.2M, 0.3M, 0.4M, 0.5M, 0.6M, 0.8M, 1.0M, or 1.2M.

[0017] In this invention, the ratio of the amount of acid in the acid solution to the mass of the alkali metal-containing layered perovskite oxide can be (0.01-2) mol:1g, preferably (0.02-1) mol:1g, for example 0.032 mol:1g, 0.5 mol:1g, 0.064 mol:1g, 0.08 mol:1g, 0.096 mol:1g, 0.1 mol:1g, 0.128 mol:1g, 0.15 mol:1g, 0.19 mol:1g, 0.2 mol:1g, or 0.3 mol:1g.

[0018] In this invention, the temperature of the ion exchange reaction is preferably 30-150°C, for example 40°C, 50°C, 60°C, 70°C, 80°C, 100°C, or 120°C. The time of the ion exchange reaction can be 2-48 hours, preferably 6-24 hours, for example 10 hours, 12 hours, 18 hours, or 24 hours.

[0019] In this invention, the ion exchange reaction is preferably carried out by liquid-phase stirring, hydrothermal method or sol-gel method.

[0020] When the ion exchange reaction is performed using a liquid-phase stirring method or a hydrothermal method, washing and drying are generally required after the ion exchange reaction is completed. The solvent used for washing can be any solvent in the art, such as deionized water and / or ethanol. Washing removes unreacted hydrogen ions and impurity anions. Drying is generally carried out in a forced-air oven; the drying temperature can be 80-120°C; and the drying time can be 8-16 hours.

[0021] The liquid-phase stirring method refers to a reaction process in which the reaction system is continuously stirred. The preferred reaction temperature for the liquid-phase stirring method is 30-90℃, for example, 30℃, 40℃, 50℃, 60℃, 70℃, 80℃, or 90℃. The preferred reaction time for the liquid-phase stirring method is 6-48 hours, for example, 10 hours, 12 hours, 18 hours, or 24 hours. The stirring speed for the liquid-phase stirring method can be 100-600 rpm, for example, 200 rpm or 300 rpm.

[0022] In some preferred embodiments, the liquid-phase stirring method includes the following process: mixing and reacting a mixture of alkali metal-containing layered perovskite oxide and acid solution at 40-100°C for 6-48 hours.

[0023] The hydrothermal method is generally carried out in a reaction vessel. The preferred temperature for the hydrothermal method is 100-160°C, for example, 120°C or 140°C. The preferred time for the hydrothermal method is 8-24 hours, for example, 10 hours, 12 hours, or 16 hours. When using the hydrothermal method, according to conventional practice in the art, the reactants generally need to be mixed thoroughly before the reaction, for example, by stirring at room temperature for 0.5-2 hours (e.g., 1 hour).

[0024] In some preferred embodiments, the hydrothermal method includes the following process: hydrothermally reacting a mixture of alkali metal-containing layered perovskite oxide and acid solution at 100-160°C for 6-48 hours.

[0025] The sol-gel method generally refers to a reaction method in which the reaction system is continuously stirred until it reaches a gel state. The rotation speed of the sol-gel method can be 100-600 rpm, for example, 200 rpm or 300 rpm. The reaction temperature of the sol-gel method is preferably 60-90℃, for example, 80℃. The reaction time of the sol-gel method is preferably 8-24 h, for example, 12 h. When using the sol-gel method, according to conventional practice in the art, the reactants generally need to be mixed evenly before the reaction, for example, stirred at room temperature for 0.5-3 h (for example, 1 h or 2 h).

[0026] When using the sol-gel method, it is preferable to also add a complexing agent to the reaction system. The complexing agent preferably includes one or more of citric acid, maleic acid, tartaric acid, ethanolamine, and sodium gluconate. The mass ratio of the complexing agent to the alkali metal-containing layered perovskite oxide can be (0.02-1):1, preferably (0.05-0.5):1, for example, 0.1:1.

[0027] In some preferred embodiments, the sol-gel method includes the following process: mixing and reacting a mixture of alkali metal-containing layered perovskite oxide, a complexing agent, and an acid solution at 60-90°C until a gel state is reached. According to conventional art, the gel state refers to a system exhibiting high viscosity and loss of fluidity, presenting a solid-like state and maintaining a certain shape.

[0028] In this invention, the calcination atmosphere is generally air, and the calcination is generally carried out in a muffle furnace.

[0029] In this invention, the calcination temperature can be 300-1200℃, for example 400℃, 600℃, 700℃, 800℃, or 900℃. The calcination time can be 1-20 hours, preferably 3-10 hours, for example 3 hours, 4 hours, or 6 hours. The calcination can be a single calcination or a double calcination. When the calcination includes a single calcination, the calcination temperature is preferably 600-1000℃, and the calcination time is preferably 3-10 hours. When the calcination includes a double calcination, the calcination process preferably includes: first calcining at 300-500℃ for 1-4 hours, cooling and re-grinding, and then calcining at 600-1000℃ for 2-8 hours.

[0030] In some preferred embodiments, when the ion exchange reaction is carried out by the sol-gel method, the calcination process includes the following steps: calcining at 300-500°C for 1-4 hours, cooling and re-grinding, and then calcining at 600-1000°C for 2-8 hours.

[0031] According to conventional practice in the art, drying is generally required before calcination. This drying is typically carried out in an oven. The drying temperature can be 70-120°C, for example, 80°C, 100°C, or 120°C. The drying time can be 6-48 hours, for example, 12 hours or 24 hours.

[0032] In this invention, during the ion exchange reaction, some A ions and A' ions in the surface layer of the alkali metal-containing layered perovskite oxide are selectively dissolved by acid under slightly acidic conditions, and hydrogen ions are exchanged into the crystal structure, but the crystal structure framework and morphology of the precursor are retained. Only the ratio of alkali metal A, A' and titanium in the surface layer of the alkali metal-containing layered perovskite oxide changes.

[0033] In this invention, the chemical formula of the alkali metal-containing layered perovskite oxide is as described above.

[0034] In this invention, the alkali metal-containing layered perovskite oxide can be commercially available or prepared in-house. The preparation method of the alkali metal-containing layered perovskite oxide preferably includes the following steps:

[0035] The mixture containing source A, source A' and titanium source is first calcined at 400-800℃ for 2-10 hours, and then the temperature is raised to 900-1300℃ for a second calcination for 2-10 hours.

[0036] The term "continued heating" refers to continuing to heat the material beyond the initial calcination temperature without cooling it down after the first calcination.

[0037] Preferably, the A source is one or more of the following: a metal salt containing alkali metal A, an alkali containing alkali metal A, and an oxide containing alkali metal A.

[0038] The salt containing alkali metal A is preferably a carbonate containing alkali metal A and / or a nitrate containing alkali metal A. The carbonate containing alkali metal A is preferably one or more of lithium carbonate, sodium carbonate, sodium bicarbonate, potassium carbonate, and potassium bicarbonate. The nitrate containing alkali metal A is preferably one or more of lithium nitrate, sodium nitrate, and potassium nitrate.

[0039] The alkali containing alkali metal A is preferably lithium hydroxide, sodium hydroxide, or potassium hydroxide.

[0040] The oxide containing alkali metal A is preferably lithium oxide, sodium oxide, or potassium oxide.

[0041] Preferably, the A' source is a metal salt containing metal A' and / or an oxide containing metal A'.

[0042] The metal salt containing metal A' is preferably a carbonate containing metal A' and / or a nitrate containing metal A'.

[0043] The oxide containing metal A' may be, for example, lanthanum oxide, yttrium oxide, or europium oxide.

[0044] Preferably, the titanium source is a titanium oxide and / or a titanium metal salt.

[0045] The titanium-containing oxide may be, for example, titanium dioxide.

[0046] The titanium-containing metal salt may be, for example, titanium chloride and / or tetrabutyl titanate.

[0047] The molar ratio of the A source, A' source and titanium source is generally determined by stoichiometry based on the chemical formula of the alkali metal-containing layered perovskite oxide. Typically, the amount of A source is increased by 1%-10% (e.g., 2%, 5% or 8%) based on the theoretical stoichiometric ratio (n+1) / 2:(n+1) / 2:n.

[0048] The method for preparing the mixture containing source A, source A' and titanium source preferably includes the following steps: grinding source A, source A' and titanium source.

[0049] The grinding method can be conventional in the art, such as ball milling. The grinding time can be 2-6 hours, for example, 4 hours.

[0050] The calcination is typically carried out in air, and the equipment used for calcination is generally a muffle furnace. The rate of heating to the temperature of the first calcination is conventional in the art, typically 3-5°C / min.

[0051] The temperature of the first calcination is preferably 500-700℃, for example 550℃ or 600℃. The duration of the first calcination is preferably 3-8 hours, for example 6 hours.

[0052] The temperature of the second calcination is preferably 1000-1300℃, for example 1200℃. The duration of the second calcination is preferably 2-6 hours, for example 4 hours.

[0053] The present invention also provides a perovskite-type heterostructure material prepared by the preparation method described above.

[0054] The present invention also provides an application of the perovskite heterostructure material as described above in secondary batteries.

[0055] In this invention, the secondary battery is preferably a lithium-ion battery or a sodium-ion battery.

[0056] The present invention also provides a secondary battery comprising the perovskite heterostructure material as described above.

[0057] Based on common knowledge in the field, the above-mentioned preferred conditions can be combined arbitrarily to obtain various preferred embodiments of the present invention.

[0058] The reagents and raw materials used in this invention are all commercially available.

[0059] The positive and progressive effects of this invention are as follows:

[0060] (1) The perovskite heterostructure material prepared by the present invention can significantly improve the diffusion rate of desolvated lithium ions from the particle surface to the bulk phase and the transfer of electrons due to the introduction of the oxygen-deficient fast ion conductor phase on the surface, thereby improving the rate performance and performing better under fast charge and discharge conditions.

[0061] (2) The perovskite heterostructure material prepared by the present invention has a stable fast ion conductor phase structure and uniform coating. In the lithium insertion / extraction state, it can provide good protection for the structure of the layered perovskite anode material and effectively prevent structural degradation. At the same time, the coating layer can suppress the side reaction between the anode interface and the electrolyte, thereby greatly extending the cycle life of the battery and improving safety.

[0062] (3) From the perspective of production process, the perovskite heterostructure material of this invention has simple and efficient operation steps, requiring no complex process flow or high equipment investment, which can effectively reduce production costs. Furthermore, the requirements for process technology are relatively low, which is conducive to its application in production enterprises of different sizes. In addition, the solution after the surface ion exchange reaction can be recycled, which conforms to the concepts of green environmental protection and sustainable development, greatly facilitating the realization of industrial-scale preparation and providing strong support for large-scale production and commercial application. Attached Figure Description

[0063] Figure 1 This is a schematic diagram of the crystal structure of the perovskite heterostructure material obtained in Example 1;

[0064] Figure 2 The image shows the XRD pattern of the perovskite-type heterostructure material obtained in Example 1.

[0065] Figure 3 SEM and TEM images of the perovskite heterostructure material obtained in Example 1;

[0066] Figure 4 The charge-discharge curves of the perovskite heterostructure material obtained in Example 1 are shown, along with a comparison of the voltage plateaus with those of commercial graphite and lithium titanate anodes.

[0067] Figure 5 The rate performance diagram of the perovskite heterostructure material obtained in Example 1 and its rate performance comparison with commercial graphite and lithium titanate anodes are shown.

[0068] Figure 6 The graph shows the cycling performance of the perovskite heterostructure material obtained in Example 1 at 20°C.

[0069] Figure 7 The image shows the XRD pattern of the perovskite heterostructure material obtained in Example 2.

[0070] Figure 8 The graph shows the cycling performance of the perovskite heterostructure material obtained in Example 2 at 20°C.

[0071] Figure 9 The image shows the XRD pattern of the perovskite-type heterostructure material obtained in Example 3. Detailed Implementation

[0072] The present invention is further illustrated below by way of embodiments, but the invention is not limited to the scope of the embodiments described herein. Experimental methods in the following embodiments that do not specify specific conditions were performed according to conventional methods and conditions, or as selected according to the product instructions.

[0073] Example 1

[0074] (1) Weigh 1.05 mmol lithium carbonate, 1 mmol lanthanum oxide and 3 mmol titanium dioxide, and mechanically ball-mill for 4 hours. Collect the raw material powder and place it in a crucible. In a muffle furnace, heat to 550°C at 3°C / min and hold for 6 hours. Without cooling, continue heating at the same rate to 1200°C and hold for 4 hours. After natural cooling, obtain Li2La2Ti3O 10 Precursor.

[0075] (2) Then add 0.5g Li2La2Ti3O 10 The powder was added to 80 mL of 0.4 M hydrochloric acid aqueous solution and stirred at 200 rpm for 24 hours at 60 °C. The product was collected and filtered with deionized water and ethanol solution, washed three times, and dried in an 80 °C oven for 12 hours. The dried powder was placed in a crucible and heated to 800 °C in a muffle furnace at 3 °C / min and held for 6 hours. After natural cooling, the perovskite-type heterostructure material Li₂La₂Ti₃O₃ was obtained. 10 @Li 0.5 La 0.5 TiO 3-δ .

[0076] Example 2

[0077] (1) Weigh 1.05 mmol lithium carbonate, 1 mmol lanthanum oxide and 3 mmol titanium dioxide, and mechanically ball-mill for 4 hours. Collect the raw material powder and place it in a crucible. In a muffle furnace, heat to 550°C at 3°C / min and hold for 6 hours. Without cooling, continue heating at the same rate to 1200°C and hold for 4 hours. After natural cooling, obtain Li2La2Ti3O 10 Precursor.

[0078] (2) Then add 0.5g Li2La2Ti3O 10 The powder was added to 80 mL of 1.2 M hydrochloric acid aqueous solution and stirred at 200 rpm for 12 hours at 80 °C. The reaction product was collected and filtered with deionized water and ethanol solution, washed three times, and dried in a forced-air oven at 80 °C for 12 hours. The dried powder was placed in a crucible and heated to 800 °C in a muffle furnace at a rate of 3 °C / min and held at that temperature for 6 hours. After natural cooling, the perovskite-type heterostructure material Li₂La₂Ti₃O₃ was obtained. 10 @Li0.33 La 0.56 TiO 3-δ .

[0079] Example 3

[0080] (1) Weigh 1.05 mmol lithium carbonate, 1 mmol lanthanum oxide and 3 mmol titanium dioxide, and mechanically ball-mill for 4 hours. Collect the raw material powder and place it in a crucible. In a muffle furnace, heat to 550°C at 3°C / min and hold for 6 hours. Without cooling, continue heating at the same rate to 1200°C and hold for 4 hours. After natural cooling, obtain Li2La2Ti3O 10 Precursor.

[0081] (2) Then add 0.5g Li2La2Ti3O 10 The powder was added to 80 mL of 0.5 M nitric acid aqueous solution and stirred at 200 rpm for 10 hours at 60 °C. The reaction product was collected and filtered with deionized water and ethanol solution, washed three times, and dried in a forced-air oven at 80 °C for 12 hours. The dried powder was placed in a crucible and heated to 800 °C in a muffle furnace at 3 °C / min and held for 6 hours. After natural cooling, the perovskite-type heterostructure material Li₂La₂Ti₃O₃ was obtained. 10 @Li 0.5 La 0.5 TiO 3-δ .

[0082] Example 4

[0083] (1) Weigh 1.05 mmol lithium carbonate, 1 mmol lanthanum oxide and 3 mmol titanium dioxide, and mechanically ball-mill for 4 hours. Collect the raw material powder and place it in a crucible. In a muffle furnace, heat to 550°C at 3°C / min and hold for 6 hours. Without cooling, continue heating at the same rate to 1200°C and hold for 4 hours. After natural cooling, obtain Li2La2Ti3O 10 Precursor.

[0084] (2) Then add 0.5g Li2La2Ti3O 10 The powder was added to 80 mL of 0.4 M hydrochloric acid aqueous solution and stirred at 200 rpm for 1 hour at room temperature. The mixture was then placed in a high-temperature, high-pressure reactor and kept at 120 °C for 12 hours. The reaction product was collected and filtered through deionized water and ethanol solution, washed three times, and dried in an 80 °C oven for 12 hours. The dried powder was placed in a crucible and heated to 800 °C in a muffle furnace at a rate of 3 °C / min, and held for 6 hours. After natural cooling, the perovskite-type heterostructure material Li₂La₂Ti₃O₃ was obtained. 10 @Li 0.33 La 0.56 TiO3-δ .

[0085] Example 5

[0086] (1) Weigh 1.05 mmol lithium carbonate, 1 mmol lanthanum oxide and 3 mmol titanium dioxide, and mechanically ball-mill for 4 hours. Collect the raw material powder and place it in a crucible. In a muffle furnace, heat to 550°C at 3°C / min and hold for 6 hours. Without cooling, continue heating at the same rate to 1200°C and hold for 4 hours. After natural cooling, obtain Li2La2Ti3O 10 Precursor.

[0087] (2) Then add 0.5g Li2La2Ti3O 10 The powder was added to a mixed solution of 80 mL of 0.4 M hydrochloric acid and 0.05 g citric acid, and stirred at 200 rpm for 2 hours at room temperature. The temperature was then raised to 80 °C and stirred at 200 rpm until a gel formed, at which point stirring was stopped. The resulting gel was dried in a 100 °C oven and placed in a crucible. The crucible was heated to 400 °C at a rate of 3 °C / min and held for 2 hours. After thorough grinding, the temperature was raised to 800 °C and held for 4 hours. Natural cooling yielded the perovskite-type heterostructure material Li₂La₂Ti₃O₃. 10 @Li 0.33 La 0.56 TiO 3-δ .

[0088] Example 6

[0089] (1) Weigh 1.05 mmol sodium carbonate, 1 mmol lanthanum oxide and 3 mmol titanium dioxide, and mechanically ball-mill for 4 hours. Collect the raw material powder and place it in a crucible. In a muffle furnace, heat the powder to 550°C at 3°C / min and hold for 6 hours. Without cooling, continue heating at the same rate to 1200°C and hold for 4 hours. After natural cooling, obtain Na2La2Ti3O. 10 Precursor.

[0090] (2) Then add 0.5g Na2La2Ti3O 10 The powder was added to 80 mL of 0.4 M hydrochloric acid aqueous solution and stirred at 200 rpm for 24 hours at 60 °C. The product was collected and filtered with deionized water and ethanol solution, washed three times, and dried in an 80 °C oven for 12 hours. The dried powder was placed in a crucible and heated to 800 °C in a muffle furnace at 3 °C / min and held for 6 hours. After natural cooling, the perovskite-type heterostructure material Na2La2Ti3O was obtained. 10 @Na 0.5 La 0.5 TiO 3-δ .

[0091] Example 7

[0092] (1) Weigh 1.05 mmol potassium carbonate, 1 mmol lanthanum oxide and 3 mmol titanium dioxide, and mechanically ball-mill for 4 hours. Collect the raw material powder and place it in a crucible. In a muffle furnace, heat to 550°C at 3°C / min and hold for 6 hours. Without cooling, continue heating at the same rate to 1200°C and hold for 4 hours. After natural cooling, K2La2Ti3O is obtained. 10 Precursor.

[0093] (2) Then add 0.5g K2La2Ti3O 10 The powder was added to 80 mL of 0.4 M hydrochloric acid aqueous solution and stirred at 200 rpm for 24 hours at 60 °C. The reaction product was collected and filtered with deionized water and ethanol solution, washed three times, and dried in an 80 °C oven for 12 hours. The dried powder was placed in a crucible and heated to 800 °C in a muffle furnace at 3 °C / min and held for 6 hours. After natural cooling, the perovskite-type heterostructure material K2La2Ti3O was obtained. 10 @K 0.5 La 0.5 TiO 3-δ .

[0094] Example 8

[0095] (1) Weigh 1.05 mmol of lithium carbonate, 1 mmol of lanthanum oxide and 2 mmol of titanium dioxide, mechanically ball mill for 4 hours, collect the raw material powder and place it in a crucible, heat it to 500°C at 3°C / min in a muffle furnace and hold it for 6 hours. Without cooling, continue heating at the same rate to 950°C and hold it for 4 hours. After natural cooling, the LiLaTiO4 precursor is obtained.

[0096] (2) Subsequently, 0.5 g of LiLaTiO4 powder was added to 80 mL of 0.4 M hydrochloric acid aqueous solution, and stirred at 200 rpm for 24 hours at 60 °C. The product after reaction was collected and filtered with deionized water and ethanol solution, washed three times, and dried in an 80 °C oven for 12 hours. The dried powder was placed in a crucible, heated to 800 °C at 3 °C / min in a muffle furnace and held for 6 hours. After natural cooling, the perovskite-type heterostructure material LiLaTiO4@Li was obtained. 0.5 La 0.5 TiO 3-δ .

[0097] Example 9

[0098] (1) Weigh 1.05 mmol of lithium carbonate, 1 mmol of yttrium oxide and 2 mmol of titanium dioxide, mechanically ball mill for 4 hours, collect the raw material powder and place it in a crucible, heat it to 550°C at 3°C / min in a muffle furnace and hold it for 6 hours, then continue to heat it to 900°C at the same heating rate and hold it for 4 hours, and obtain the LiYTiO4 precursor after natural cooling.

[0099] (2) Subsequently, 0.5 g of LiYTiO4 powder was added to 80 mL of 0.6 M hydrochloric acid aqueous solution, and stirred at 200 rpm for 24 hours at 60 °C. The product after reaction was collected and filtered with deionized water and ethanol solution, washed three times, and dried in an 80 °C forced-air oven for 12 hours. The dried powder was placed in a crucible, heated to 800 °C in a muffle furnace at 3 °C / min and held for 6 hours. After natural cooling, the perovskite heterostructure material LiYTiO4@Li was obtained. 0.5 Y 0.5 TiO 3-δ .

[0100] Example 10

[0101] (1) Weigh 1.05 mmol lithium carbonate, 1 mmol europium oxide and 2 mmol titanium dioxide, mechanically ball mill for 4 hours, collect the raw material powder and put it into a crucible, heat it to 550°C at 3°C / min in a muffle furnace and hold it for 6 hours. Without cooling, continue heating to 950°C at the same heating rate and hold it for 4 hours. After natural cooling, the LiEuTiO4 precursor is obtained.

[0102] (2) Subsequently, 0.5 g of LiEuTiO4 powder was added to 80 mL of 0.6 M hydrochloric acid aqueous solution, and stirred at 200 rpm for 24 hours at 60 °C. The product after reaction was collected and filtered with deionized water and ethanol solution, washed three times, and dried in a forced-air oven at 80 °C for 12 hours. The dried powder was placed in a crucible, heated to 800 °C at 3 °C / min in a muffle furnace and held at that temperature for 6 hours. After natural cooling, the perovskite heterostructure material LiEuTiO4@Li was obtained. 0.5 Eu 0.5 TiO 3-δ .

[0103] Example 11

[0104] Compared with Example 1, except that the concentration of hydrochloric acid in step (2) was adjusted to 0.2M, all other operations and conditions were the same as in Example 1, and the perovskite-type heterostructure material Li2La2Ti3O was obtained after natural cooling. 10 @Li 0.5 La 0.5 TiO 3-δ .

[0105] Example 12

[0106] Compared with Example 1, except that the concentration of hydrochloric acid in step (2) was adjusted to 0.8M, all other operations and conditions were the same as in Example 1, and the perovskite-type heterostructure material Li2La2Ti3O was obtained after natural cooling. 10 @Li 0.5 La 0.5 TiO 3-δ .

[0107] Example 13

[0108] Compared with Example 1, except that the 0.4M hydrochloric acid in step (2) was replaced with 0.4M nitric acid, all other operations and conditions were the same as in Example 1, and the perovskite-type heterostructure material Li2La2Ti3O was obtained after natural cooling. 10 @Li 0.5 La 0.5 TiO 3-δ .

[0109] Example 14

[0110] Compared with Example 1, except that the temperature of the reaction with acid in step (2) was adjusted from 60°C to 40°C, all other operations and conditions were the same as in Example 1, and the perovskite-type heterostructure material Li2La2Ti3O was obtained after natural cooling. 10 @Li 0.5 La 0.5 TiO 3-δ .

[0111] Example 15

[0112] Compared with Example 1, except that the reaction time with acid in step (2) was adjusted from 24 hours to 12 hours, all other operations and conditions were the same as in Example 1, and the perovskite-type heterostructure material Li2La2Ti3O was obtained after natural cooling. 10 @Li 0.5 La 0.5 TiO 3-δ .

[0113] Example 16

[0114] Compared with Example 1, except that the calcination temperature in step (2) was adjusted from 800℃ to 700℃, all other operations and conditions were the same as in Example 1, and the perovskite-type heterostructure material Li2La2Ti3O was obtained after natural cooling. 10 @Li 0.5 La 0.5 TiO 3-δ .

[0115] Example 17

[0116] Compared with Example 1, except that the calcination time in step (2) was adjusted from 6 hours to 3 hours, all other operations and conditions were the same as in Example 1, and the perovskite-type heterostructure material Li2La2Ti3O was obtained after natural cooling. 10 @Li 0.5 La 0.5 TiO 3-δ .

[0117] Comparative Example 1

[0118] Commercial graphite (Ningbo Shanshan P15-X).

[0119] Comparative Example 2

[0120] Lithium titanate (Gree Titanium New Energy LTO).

[0121] Effect Example

[0122] Sample characterization: X-ray diffraction (XRD) was used to acquire sample structural information, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to acquire sample morphology and ultrastructure information, Chenhua electrochemical workstation was used to test sample electrochemical properties, and Blue Battery testing system was used to characterize sample battery performance.

[0123] Figure 1 This is a schematic diagram of the crystal structure of the heterostructure anode material prepared in Example 1, whose bulk phase is layered Li₂La₂Ti₃O₂. 10 Phase, surface is a fast ion conductor Li 0.5 La 0.5 TiO 3-δ Phase. Since ion exchange and structural reconstruction occur in situ and are uniform, there is no clear boundary between the inner and outer lattice coherence. XRD tests were performed on the perovskite heterostructure material prepared in Example 1, and the results are shown in [Figure 1]. Figure 2 The results confirmed that the heterostructure consisted of layered Li₂La₂Ti₃O₃. 10 Phase and fast ion conductor Li 0.5 La 0.5 TiO 3-δ The phase composition matches the standard spectrum well. Figure 3 These are SEM and TEM images of the perovskite-type heterostructure material prepared in Example 1. The SEM image shows that the material is cubic with a particle size of 2-5 micrometers. The TEM image confirms that the material is a heterostructure, with the bulk phase being Li₂La₂Ti₃O. 10 Phase, surface is Li 0.5 La 0.5 TiO 3-δ Phase, surface Li0.5 La 0.5 TiO 3-δ The thickness of the coating layer is approximately 2–2.5 nm. Figure 7 This is the XRD pattern of the perovskite-type heterostructure material prepared in Example 2. The results confirm that the heterostructure consists of layered Li₂La₂Ti₃O₂. 10 Phase and fast ion conductor Li 0.33 La 0.56 TiO 3-δ The phase composition matches the standard spectrum well. Figure 9 This is the XRD pattern of the perovskite-type heterostructure material prepared in Example 3. The results confirm that the heterostructure consists of layered Li₂La₂Ti₃O₂. 10 Phase and fast ion conductor Li 0.5 La 0.5 TiO 3-δ The phase composition matches the standard spectrum well.

[0124] The chemical formulas of the perovskite heterostructure materials prepared in Examples 1-17 were determined by XRD characterization.

[0125] Electrochemical performance tests of the perovskite heterostructure materials prepared in Examples 1-17 and Comparative Examples 1-2 were conducted using CR2016 coin cells. The counter electrode was a 1 mm thick, 15 mm diameter lithium metal sheet. The working electrodes consisted of the perovskite heterostructure materials prepared in each example or Comparative Examples 1-2, conductive acetylene black, and binder polyvinylidene fluoride (PVDF) in a mass ratio of 8:1:1. The specific preparation process for the negative electrode was as follows: First, 160 mg of perovskite heterostructure material, 20 mg of conductive acetylene black, and 1 mL of N-dimethylpyrrolidone solution of PVDF (20 mg / mL) were mixed to prepare a slurry. The slurry was then coated onto copper foil, dried in a vacuum oven at 120°C, and then cut into 12 mm diameter electrode sheets using a die-cutting machine. The active material loading on the electrode sheets was 1.5–2.0 mg / cm². 2 The battery was assembled using Whatman's GF / C glass fiber separator and 1M lithium hexafluorophosphate electrolyte (solvent-to-volume ratio DEC:EC = 1:1), in an argon glove box. During assembly, the oxygen and water vapor content were both below 0.1 ppm. Electrochemical testing was performed using a CHI760e electrochemical workstation from Shanghai Chenhua and a LAND-CT2001C battery testing system from Wuhan Landian. Test results are shown below. Figures 4-6 , Figure 8 See Table 1.

[0126] Figure 4The data shows the charge-discharge curves of the perovskite heterostructure material prepared in Example 1 at 0.1C. The results indicate that its specific capacity is 206 mAh / g and the voltage plateau is at 0.6V. Compared with the spinel lithium titanate anode, the capacity is increased by 31 mAh / g and the voltage plateau is decreased by 0.95V. Compared with the graphite anode, the voltage plateau is increased by 0.5V. Therefore, it has excellent potential high energy density and intrinsic safety.

[0127] Figure 5 The rate performance of the perovskite heterostructure material prepared in Example 1 is shown. The results indicate that its average specific capacity at rates of 0.1, 0.5, 1, 2, 5, 10, 20, 50, and 100C is 204, 195, 186, 177, 165, 157, 152, 136, and 120 mAh / g, respectively. It exhibits excellent capacity retention at high rates, which is significantly better than that of commercial graphite and lithium titanate anodes.

[0128] Figure 6 The perovskite heterostructure material prepared in Example 1 exhibits excellent long-cycle stability at a rate of 20C, with a capacity retention of 86.2% after 10,000 cycles. Figure 8 The perovskite heterostructure material prepared in Example 2 exhibits excellent long-cycle stability at a rate of 20C, with a capacity retention of 87.5% after 10,000 cycles.

[0129] Table 1

[0130] 0.1C 0.5C 1C 2C 5C 10C 20C 50C 100C Example 1 204 195 186 177 165 157 152 136 120 Example 2 201 192 188 175 164 155 147 133 118 Example 3 200 188 182 170 157 144 137 131 110 Example 4 202 188 179 170 158 149 138 126 109 Example 5 198 182 173 162 152 140 128 117 105 Example 6 163 155 149 144 138 134 128 109 99 Example 7 157 151 145 140 135 129 124 106 97 Example 8 188 180 171 165 157 150 144 130 115 Example 9 185 176 167 163 155 148 141 127 111 Example 10 179 172 165 157 150 141 130 117 100 Example 11 202 192 181 171 158 148 140 129 112 Example 12 200 189 177 169 156 142 133 124 110 Example 13 196 180 168 155 148 134 121 109 98 Example 14 199 185 174 165 156 147 138 127 113 Example 15 201 188 180 171 160 148 135 124 112 Example 16 182 170 161 153 142 134 122 110 99 Example 17 194 179 170 157 146 138 129 120 108 Comparative Example 1 372 345 302 236 132 96 62 33 20 Comparative Example 2 175 170 164 155 146 135 124 99 73

[0131] While specific embodiments of the present invention have been described above, those skilled in the art should understand that these are merely illustrative examples, and the scope of protection of the present invention is defined by the appended claims. Those skilled in the art can make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, but all such changes and modifications fall within the scope of protection of the present invention.

Claims

1. A perovskite heterostructure material, characterized in that, The alkali metal-containing layered perovskite oxide and the heterostructure coating layer on the surface thereof are coherent in the inner and outer structure lattices without obvious interface; The chemical formula of the alkali metal-containing layered perovskite oxide is A (n+1) / 2 A' (n+1) / 2 B n O 3n+1 , n = 1, 2, 3, respectively corresponding to single-layer, double-layer and triple-layer structure; the chemical formula of the heterostructure coating layer is A 3y A' 2 / 3-y BO 3-δ , 0.1≤y≤0.2; A is one or more of Li, Na and K, A' is a lanthanide and / or Y, and B is Ti.

2. The perovskite heterostructure material of claim 1, wherein The perovskite-type heterostructure material satisfies one or more of the following conditions: (1) the charge and discharge voltage platform of the perovskite-type heterostructure material is 0.4-0.8V; (2) the lanthanide rare earth element is one or more of La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu; (3) in the chemical formula of the heterostructure coating layer, 0.1≤y≤0.17; (4) the thickness of the heterostructure coating layer is 2-10nm.

3. The perovskite heterostructure material of claim 1, wherein In the chemical formula of the heterostructure coating layer, y is 0.11, 0.15 or 0.

17.

4. A method for producing the perovskite heterostructure material according to any one of claims 1 to 3, characterized by, The method comprises the following steps: The perovskite-type heterostructure material is prepared by ion exchange reaction of a mixture of the alkali metal-containing layered perovskite oxide and an acid solution at 20-160℃, followed by calcination.

5. The method for preparing perovskite-type heterostructure material as described in claim 4, characterized in that, The preparation method satisfies one or more of the following conditions: (1) the acid solution is one or more of hydrochloric acid, nitric acid, citric acid, acetic acid, formic acid, propionic acid, benzoic acid and ethylenediaminetetraacetic acid; (2) the solvent in the acid solution is deionized water; (3) the concentration of the acid solution is 0.1-2.0M; (4) the ratio of the amount of substance of the acid in the acid solution to the mass of the alkali metal-containing layered perovskite oxide is (0.01-2) mol:1 g.

6. The method of producing a perovskite heterostructure material according to claim 5, wherein The concentration of the acid solution is 0.2-1.5M.

7. The method of producing a perovskite heterostructure material according to claim 6, wherein The concentration of the acid solution is 0.2M, 0.3M, 0.4M, 0.5M, 0.6M, 0.8M, 1.0M or 1.2M.

8. The method for preparing perovskite-type heterostructure material as described in claim 5, characterized in that, The ratio of the amount of substance of the acid in the acid solution to the mass of the alkali metal-containing layered perovskite oxide is (0.02-1) mol:1 g.

9. The method of producing a perovskite heterostructure material according to claim 8, wherein The ratio of the amount of substance of the acid in the acid solution to the mass of the alkali metal-containing layered perovskite oxide is 0.032 mol:1 g, 0.5mol:1 g, 0.064 mol:1 g, 0.08 mol:1 g, 0.096 mol:1 g, 0.1 mol:1 g, 0.128 mol:1 g, 0.15 mol:1 g, 0.19 mol:1 g, 0.2 mol:1 g or 0.3 mol:1 g.

10. The method for preparing perovskite-type heterostructure material as described in claim 4, characterized in that, The preparation method satisfies one or more of the following conditions: (1) the temperature of the ion exchange reaction is 30-150℃; (2) the time of the ion exchange reaction is 2-48h; (3) the temperature of the calcination is 300-1200℃; (4) the time of the calcination is 1-20h; (5) the preparation method of the alkali metal-containing layered perovskite oxide comprises the following steps: The mixture containing A source, A' source and titanium source is first calcined at 400-800℃ for 2-10h, and then heated to 900-1300℃ for second calcination for 2-10h.

11. The method of producing a perovskite heterostructure material according to claim 10, wherein The ion exchange reaction is carried out at a temperature of 40℃, 50℃, 60℃, 70℃, 80℃, 100℃ or 120℃.

12. The method for preparing the perovskite-type heterostructure material as described in claim 10, characterized in that, The ion exchange reaction is carried out for a time of 6-24h.

13. The method for preparing perovskite-type heterostructure material as described in claim 12, characterized in that, The ion exchange reaction is carried out for a time of 10h, 12h, 18h or 24h.

14. The method for preparing perovskite-type heterostructure material as described in claim 10, characterized in that, The calcination is carried out at a temperature of 400℃, 600℃, 700℃, 800℃ or 900℃.

15. The method for preparing the perovskite-type heterostructure material as described in claim 10, characterized in that, The calcination is carried out for a time of 3-10h.

16. The method of producing a perovskite heterostructure material according to claim 15, wherein The calcination is carried out for a time of 3h, 4h or 6h.

17. The method for preparing perovskite-type heterostructure material as described in claim 10, characterized in that, The first calcination is carried out at a temperature of 500-700℃.

18. The method of producing a perovskite heterostructure material according to claim 17, wherein The first calcination is carried out at a temperature of 550℃ or 600℃.

19. The method for preparing perovskite-type heterostructure material as described in claim 10, characterized in that, The first calcination is carried out for a time of 3-8h.

20. The method for preparing the perovskite-type heterostructure material as described in claim 19, characterized in that, The first calcination is carried out for a time of 6h.

21. The method for preparing the perovskite-type heterostructure material as described in claim 10, characterized in that, The second calcination is carried out at a temperature of 1000-1300℃.

22. The method of claim 21, wherein the perovskite heterostructure material is prepared by a method comprising: The second calcination is carried out at a temperature of 1200℃.

23. The method for preparing perovskite-type heterostructure material as described in claim 10, characterized in that, The second calcination is carried out for a time of 2-6h.

24. The method of producing a perovskite heterostructure material according to claim 23, wherein The second calcination is carried out for a time of 4h.

25. The method for preparing perovskite-type heterostructure materials as described in claim 4, characterized in that, The ion exchange reaction is carried out by a liquid phase stirring method, a hydrothermal method or a sol-gel method.

26. The method of producing a perovskite heterostructure material according to claim 25, wherein The liquid phase stirring method is carried out at a temperature of 30-90℃.

27. The method of producing a perovskite heterostructure material according to claim 26, wherein The liquid phase stirring method is carried out at a temperature of 30℃, 40℃, 50℃, 60℃, 70℃, 80℃ or 90℃.

28. The method for preparing perovskite-type heterostructure material as described in claim 25, characterized in that, The liquid phase stirring method is carried out for a time of 6-48h.

29. The method of producing a perovskite heterostructure material according to claim 28, wherein The liquid phase stirring method is carried out for a time of 10h, 12h, 18h or 24h.

30. The method for preparing perovskite-type heterostructure material as described in claim 25, characterized in that, The liquid phase stirring method is carried out at a rotation speed of 100-600rpm.

31. The method of producing a perovskite heterostructure material according to claim 30, wherein The liquid phase stirring method is carried out at a rotation speed of 200rpm or 300rpm.

32. The method of producing a perovskite heterostructure material according to claim 25, wherein The hydrothermal method is carried out at a temperature of 100-160℃.

33. The method of producing a perovskite heterostructure material according to claim 32, wherein The hydrothermal method is carried out at a temperature of 120℃ or 140℃.

34. The method of producing a perovskite heterostructure material according to claim 25, wherein The hydrothermal method is carried out for a time of 8-24h.

35. The method of producing a perovskite heterostructure material according to claim 34, wherein The hydrothermal method is carried out for a time of 10h, 12h or 16h.

36. The method of producing a perovskite heterostructure material according to claim 25, wherein The sol-gel method is carried out at a temperature of 60-90℃.

37. The method of producing a perovskite heterostructure material according to claim 36, wherein The sol-gel method is carried out at a temperature of 80℃.

38. The method for preparing perovskite-type heterostructure material as described in claim 25, characterized in that, The sol-gel method is carried out for a time of 8-24h.

39. The method of producing a perovskite heterostructure material according to claim 38, wherein The sol-gel method is carried out for a time of 12h.

40. The method for preparing perovskite-type heterostructure material as described in claim 25, characterized in that, When the sol-gel method is used, a complexing agent also needs to be added to the reaction system.

41. The method of producing a perovskite heterostructure material according to claim 40, wherein The complexing agent comprises one or more of citric acid, maleic acid, tartaric acid, ethanolamine and sodium gluconate.

42. The method for preparing perovskite-type heterostructure material as described in claim 40, characterized in that, The mass ratio of the complexing agent to the alkali metal-containing layered perovskite oxide is (0.02-1):

1.

43. The method of producing a perovskite heterostructure material according to claim 42, wherein The mass ratio of the complexing agent to the alkali metal-containing layered perovskite oxide is (0.05-0.5):

1.

44. The method of producing a perovskite heterostructure material according to claim 43, wherein The mass ratio of the complexing agent to the alkali metal-containing layered perovskite oxide is 0.1:

1.

45. The method of producing a perovskite heterostructure material according to claim 25, wherein The liquid phase stirring method comprises the following process: mixing a mixture of the alkali metal-containing layered perovskite oxide and an acid solution at 40-100℃ for 6-48h; Or, the hydrothermal method comprises the following process: carrying out a hydrothermal reaction on a mixture of the alkali metal-containing layered perovskite oxide and an acid solution at 100-160℃ for 6-48h; Or, the sol-gel method comprises the following process: mixing a mixture of the alkali metal-containing layered perovskite oxide, a complexing agent and an acid solution at 60-90℃ until a gel state is reached.

46. Use of the perovskite heterostructure material of any one of claims 1-3 in a secondary battery.

47. A secondary battery comprising the perovskite heterostructure material of any one of claims 1-3.

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