CN113097454A

CN113097454A - Porous confined multi-metal composite oxide material and preparation method and application thereof

Info

Publication number: CN113097454A
Application number: CN202010023063.4A
Authority: CN
Inventors: 黄富强; 刘子超; 董武杰
Original assignee: Shanghai Institute of Ceramics of CAS
Current assignee: Shanghai Institute of Ceramics of CAS
Priority date: 2020-01-09
Filing date: 2020-01-09
Publication date: 2021-07-09
Anticipated expiration: 2040-01-09
Also published as: CN113097454B

Abstract

The invention relates to a porous limited-domain multi-metal composite oxide material and a preparation method and application thereof, wherein the structural general formula of the porous limited-domain multi-metal composite oxide material is A_eO_f@M_xO_{y z‑}(ii) a The M is_xO_{y z‑}Is an ordered mono-, quasi-mono-, or twin-crystal structure, has a porous structure, and A_eO_fConfinement deposition at M_xO_{y z‑}Forming a composite structure among the porous structures; x is more than or equal to 1 and less than or equal to 2, y is more than or equal to 1 and less than or equal to 5, z is more than or equal to 0.1 and less than or equal to 0.9, e is more than or equal to 1 and less than or equal to 3, and f is more than or equal to 1 and less than or equal to 4; wherein A is selected from iron element and nickelAt least one of elements, cobalt elements, manganese elements, chromium elements, zinc elements and tin elements; m is at least one of niobium, molybdenum, titanium, vanadium, tungsten, tantalum and zirconium.

Description

Porous confined multi-metal composite oxide material and preparation method and application thereof

Technical Field

The invention relates to an electrochemical energy storage material, in particular to a porous confined multi-metal composite oxide material and a preparation method and application thereof, belonging to the field of material preparation.

Background

The energy crisis is global, and the pollution and non-regenerability of traditional fossil energy are widely accepted and regarded worldwide. Under the background, the electrochemical energy storage technology has gained wide attention and great development from the industry and academia. Lithium ion batteries and supercapacitors are the latest technology in the field of electrochemical energy storage, and the first proposal of LiCoO was made by the company SONY of Japan in 1989₂As Li source anode, petroleum coke as cathode, LiPF₆The lithium ion battery is dissolved in propylene carbonate and ethylene carbonate as electrolyte, and a novel lithium ion battery is developed and commercialized successfully in 1991. Compared with the traditional secondary battery, the lithium ion battery has the advantages of high open-circuit voltage, large energy density, long service life and the like, and can be applied to the fields of portable electronic equipment such as mobile phones, video cameras, notebook computers and the like, military equipment, medical equipment and the like. At present, lithium ion batteries are developing into new fields such as electric vehicles and large-scale energy storage, but the stability, safety, energy density and power density of the lithium ion batteries cannot meet the requirements of practical application, so that a novel high-performance energy storage material needs to be developed, and the application market of the lithium ion batteries is further expanded.

The negative electrode material of the current commercial lithium ion battery mainly comprises artificial graphite (natural modified graphite and mesocarbon microbeads), a silicon-carbon composite material and lithium titanate with more stable performance. The graphite material and the silicon-carbon composite negative electrode material with the hexagonal layered structure are close to the maximum theoretical capacity of the material under low battery use rate, the cycle life can reach more than 500 times, and the battery requirements of portable electronic equipment can be basically met. Long-time circulation under high-multiplying power working condition, because electrode material is pulverized,The battery is completely deactivated due to falling off, and the capacity of the battery is attenuated due to the problems of poor conductivity, volume effect and the like. The lithium titanate has the advantages of zero-strain lithium intercalation structure, long cycle life and higher safety. The three-dimensional pore structure of the lithium titanate crystal provides a passage for lithium ion diffusion and simultaneously can keep the stability of the structure in the lithium deintercalation process, the generation of an SEI film is inhibited by the working potential near 1.55V, the volume change before and after lithium deintercalation of lithium titanate is rarely less than 1%, and the advantages of long service life and high stability can be realized (Ultrathin Li₄Ti₅O₁₂Nanosheet Based Hierarchical Microspheres for HighRate and Long-Cycle Life Li⁺Ion batteries, advanced Energy Materials, 2017,7(21): 1700950.). But a lower theoretical capacity (175mA h g) due to the reduction of only about 60% of the titanium (IV)^-1) Limiting the application of lithium titanate batteries. Therefore, it is urgent to develop a novel electrode material having both high rate charge and discharge stability and large capacity.

Metal oxides as negative electrode materials, e.g. TiO₂，Nb₂O₅，V₂O₅，MoO₂，WO₂，Fe₂O₃，FeO，Co₃O₄CuO, ZnO, etc. (metals and oxides as materials for Li ion batteries, chemical reviews, 2013,113(7):5364-5457.), which can be classified into three classes according to their lithium-storing reaction mechanism: one is an intercalation mechanism, and oxides with the mechanism can keep a stable crystal structure without damage and generate limited volume change in the processes of lithium intercalation and lithium deintercalation, such as TiO₂，Nb₂O₅，V₂O₅，MoO₂，WO₂，Li₄Ti₅O₁₂The oxide of the transition metal has the advantages of high multiplying power and high stability, but the energy storage capacity is relatively low. The other two mechanisms include a conversion mechanism and an alloy mechanism, wherein the former forms lithium oxide and a transition metal element, and the latter forms an alloy of the transition metal and lithium to store energy respectively, so that the lithium storage battery has the advantage of large lithium storage capacity, but the lithium storage battery generates electricity due to huge volume changeThe stability and rate capability are very poor.

Generally, the transition metal oxide can realize higher lithium storage capacity only under the conditions of a large amount of additives and delicate and complex structural design, such as the use of graphene and carbon fiber composite niobium oxide, or the preparation of special nano structures such as nano sheets, nano wires, multilevel structures and the like, for example, the silver ear-shaped MoO₂The nanosheet is used as the negative electrode, the larger surface area of the nanosheet reduces the actual effective current density, the structural change is more gradual, and the flaky MoO₂The ion diffusion speed is accelerated, the structure is more uniformly evolved, and 600mA h g is obtained^-1The stable capacity of (2). Also for example, porous graphene-composited Nb prepared by Sun et al₂O₅The electrode can still normally work and keep 90mA h g under the working multiplying power of 100C (the charging/discharging time is less than 36 seconds)^-1Capacity of (Three-dimensional cellulose-graphene/niobia composite architecture for ultra-high-rate energy storage science, 2017,356(6338): 599-. The method has been proved to improve the performance of the electrode material in a large amount, but the optimization method is relatively difficult to control, consumes time and labor under industrial preparation conditions, is high in cost, and greatly limits the potential of realizing industrial application.

Thus, metal oxides have the potential to produce high performance electrodes, but still suffer from several problems: (1) the charge-discharge reversible specific capacity of the material is small; (2) the Solid Electrolyte Interface (SEI) is unstable during charge and discharge cycles, resulting in consumption of lithium source and collapse of the battery; (3) the performance of the material is unstable in the charge and discharge processes; (4) the electronic conductivity and the ionic conductivity of the material cannot realize high-rate working performance; (5) the preparation process is complicated, the cost is high and pollution is caused.

Disclosure of Invention

Based on the problems of metal oxide as an energy storage material, the invention aims to provide a porous confined multi-metal composite oxide material with a special microstructure and a preparation method and application thereof.

In one aspect, the invention provides a porous confined multi-metal composite oxide material, and the structural general formula of the porous confined multi-metal composite oxide material is A_eO_f@M_xO_y-z(ii) a The M is_xO_y-zIs an ordered mono-, quasi-mono-, or twin-crystal structure, has a porous structure, and A_eO_fConfinement deposition at M_xO_y-zForming a composite structure among the porous structures; x is more than or equal to 1 and less than or equal to 2, y is more than or equal to 1 and less than or equal to 5, z is more than or equal to 0.1 and less than or equal to 0.9, e is more than or equal to 1 and less than or equal to 3, and f is more than or equal to 1 and less than or equal to 4;

wherein A is selected from at least one of iron element, nickel element, cobalt element, manganese element, chromium element, zinc element and tin element; m is at least one of niobium, molybdenum, titanium, vanadium, tungsten, tantalum and zirconium.

In the invention, the porous limited-domain multi-metal composite oxide material has a more ordered crystal structure, which is beneficial to improving the stability of the electrochemical process of the material and reducing a large amount of grain boundary resistance possibly brought by polycrystal. Moreover, the porous confined multi-metal composite oxide material has the defects that the size is smaller than 1 nanometer in the crystal, micropores provide a large number of dangling bonds with high reaction activity, the energy storage capacity of the material is improved, and the micropores with the pore diameter smaller than 2 nanometers and the mesopores with the pore diameter not less than 2 nanometers and not more than 50nm provide buffer for the volume change of the electrochemical process of the material, improve the stability of the material, provide channels for electrolyte diffusion and improve the high-rate working performance of the material; transition type or alloy type lithium-storing metal element oxide (A) with further limited domain growth_eO_f) The lithium ion battery has extremely high reaction activity due to the size effect, and the poor conductivity and the volume change caused by lithium intercalation and lithium deintercalation are greatly relieved due to the surrounding wrapped intercalation metal oxide; metal element (M) in mixed valence state_xO_y-zWherein M element with two or more valence states exists) improves the conductivity of the material, so that the electrochemical reaction can be performed more uniformly and smoothly.

Preferably, M is_xO_y-zThe porous structure comprises mesopores with the aperture of more than or equal to 2nm and less than or equal to 50nm and micropores with the aperture of less than 2 nm; preferably, the aperture of the mesopores is 30-40 nm, and the aperture of the micropores is more than or equal to 1nm and less than 2 nm.

Preferably, the atomic ratio of A is 0.1 to 20 at%.

Preferably, the size of the porous confined multi-metal composite oxide material is 10 nm-50 μm.

In another aspect, the present invention further provides a preparation method of the porous confinement multi-metal composite oxide material, including:

(1) precursor N of multi-element metal composite oxide_aM_bO_cAdding the mixed solution into an acid solution containing A ions and mixing to obtain a mixed solution, wherein the N element is at least one of alkali metal, alkaline earth metal, La and Al, a is more than or equal to 1 and less than or equal to 2, b is more than or equal to 1 and less than or equal to 8, and c is more than or equal to 3 and less than or equal to 17;

(2) preserving the temperature of the obtained mixed solution at 50-90 ℃ for 1 hour-7 days under normal pressure, and filtering to obtain particles 1;

(3) adding the obtained particles 1 into an acid solution containing A ions, mixing, then placing the mixture into a reaction kettle, preserving the heat for 1 hour to 7 days at the temperature of between 100 and 140 ℃, and filtering to obtain particles 2;

(4) adding the obtained particles 2 into an acid solution containing A ions, mixing, then placing the mixture into a reaction kettle, preserving the heat for 1 hour to 7 days at the temperature of 150 to 220 ℃, and filtering to obtain an intermediate product;

(5) and calcining the obtained intermediate product for 1-24 hours at 400-1000 ℃ in a protective atmosphere to obtain the porous limited-area multi-metal composite oxide material.

In the present disclosure, a multi-metal composite oxide precursor N_aM_bO_cAdding the mixture into an acid solution containing A ions, and mixing to obtain a mixed system 1. And then placing the mixed system 1 in a normal pressure environment at 50-90 ℃, and preserving heat for 1 hour-7 days, so that the acid solution containing A ions etches the surface layer of the multi-metal composite oxide and ions on the shallow surface layer, ions near the surface layer are slowly dissolved out, and the stability of the structure and the morphology is kept. Secondly, filtration and addition of an acidic solution containing ions a give a mixed system 2. And transferring the mixed system 2 into a high-temperature high-pressure reaction vessel, raising the temperature to 100-140 ℃, and preserving the heat for 1 hour-7 days to promote the dynamics of the etching reaction. Finally, filtering and adding an acid solution containing A ions to obtain a mixtureIs series 3. And (3) raising the reaction temperature of the mixed system 3 to 150-220 ℃, preserving the heat for 1 hour-7 days to enable the N element to be completely dissolved out from the precursor, simultaneously promoting the A element in the solution to be separated out at high temperature, depositing the A element on the surface and in holes of the oxide in an extremely small size, and promoting the ordering of the crystal structure of the oxide to obtain an intermediate product (solid particles). Finally, the obtained solid particles are placed in an inert atmosphere furnace or a vacuum tube furnace for heating and annealing at the temperature of 400-1000 ℃ for 1-24 hours to finally obtain the multi-metal oxide A with the metal atoms in the mixed valence state_eO_f@M_xO_y-z。

Preferably, the acid in the acidic solution containing the ion A is at least one of hydrochloric acid, nitric acid, acetic acid, hydroiodic acid, hydrobromic acid, formic acid and ethylenediamine tetraacetic acid; the precursor of the A ion is at least one of chloride of the A element, bromide of the A element, iodide of the A element, oxalate of the A element, nitrate of the A element and sulfate of the A element.

Preferably, in the step (1), the molar content of the a ions in the acidic solution containing the a ions is the precursor N of the multi-metal composite oxide_aM_bO_c1 to 100 times, preferably 2 to 10 times; the molar content of acid in the acidic solution containing the A ions is the precursor N of the multi-element metal composite oxide_aM_bO_c1 to 50 times, preferably 1 to 3 times; the concentration of the A ions in the acidic solution containing the A ions is 0.1-6 mol/L. That is, the multi-metal composite oxide precursor N_aM_bO_cAnd the molar ratio of A ions is 1: (1 to 100), preferably 1: (2-10) precursor N of the multi-metal composite oxide_aM_bO_cAnd the molar ratio of the acid in the acidic solution containing the A ions is 1: (1 to 50), preferably 1: (1-3).

Preferably, in the step (3), the molar content of the a ions in the acidic solution containing the a ions is the precursor N of the multi-metal composite oxide_aM_bO_c1 to 100 times, preferably 2 to 10 times, and the molar content of the acid is the multi-metal composite oxide precursor N_aM_bO_c1 to 50 times, preferably 1 to 3 times, and the concentration of the A ions in the acidic solution containing the A ions is 0.1 to 6 mol/L. Among them, it is preferable that the concentration and the addition volume of the acidic solution containing the ion A in the step (3) are the same as those in the step (1).

Preferably, the molar content of the A ions in the acidic solution containing the A ions is N, which is a precursor of the multi-metal composite oxide_aM_bO_c1 to 100 times, preferably 2 to 10 times, and the molar content of the acid is the multi-metal composite oxide precursor N_aM_bO_c1 to 50 times, preferably 1 to 3 times, and the concentration of the A ions in the acidic solution containing the A ions is 0.1 to 6 mol/L. Among them, it is preferable that the concentration and the addition volume of the acidic solution containing the ion A in the step (4) are the same as those in the step (1).

Preferably, in the step (5), the protective atmosphere is a vacuum atmosphere, an inert atmosphere or a nitrogen atmosphere; the inert atmosphere is at least one of He, Ne and Ar.

In another aspect, the invention also provides an application of the porous confinement multi-metal composite oxide material as an electrode material of an electrochemical energy storage device.

Has the advantages that:

in the invention, the special composition and microstructure of the porous confinement multi-metal composite oxide material combine the respective advantages of an insertion mechanism and a conversion mechanism, thereby greatly increasing the reversible lithium storage capacity of the porous confinement multi-metal composite oxide material and ensuring the rate capability and stability of the electrode work; therefore, the material can be used as an electrode material with high lithium storage capacity, high rate capability and cycling stability, and can meet the requirement of the market on a high-performance lithium ion battery.

Drawings

FIG. 1 shows Fe @ HNbO supported on iron oxide prepared in example 1₃(a) And a transmission electron micrograph of iron oxide-supported niobium pentoxide (b);

FIG. 2 is LiNbO, a precursor prepared in example 1₃Intermediate product iron oxide loaded columbate Fe @ HNbO₃And iron oxide-supported black niobium pentoxideFe oxide @ Nb₂O_5-z) X-ray powder diffraction pattern of (a);

FIG. 3 is a linear sweep voltammogram (a) of the iron oxide-supported black niobium pentoxide prepared in example 1 and a white niobium pentoxide Nb calculated based on the linear sweep voltammetry₂O₅And iron oxide-supported black niobium pentoxide;

FIG. 4 shows the rate capability of the iron oxide-supported niobium pentoxide lithium ion battery prepared in example 1 and niobium pentoxide Nb directly synthesized by the sol-gel method₂O₅Comparing the multiplying power performance;

FIG. 5 shows iron oxide-supported niobium pentoxide (sample 6), chromium oxide-supported niobium pentoxide (sample 5), commercial graphite electrode (sample 1), silicon-carbon electrode (sample 2), lithium titanate electrode (sample 3), and unsupported black niobium pentoxide Nb prepared according to the invention₂O_5-z(sample 4) capacity comparison at different charge and discharge rates;

FIG. 6 shows that the niobium pentoxide supported on iron oxide prepared in example 1 has a concentration of 3-7mV s^-1Cyclic voltammograms (a) at different voltage sweep rates and, 5mV s^-1Iron-loaded niobium pentoxide Fe oxide @ Nb at scanning speed₂O_5-zThe cyclic voltammetry curve (outer curve) (b) and the cyclic voltammetry curve (inner curve) with capacitance characteristics obtained by analog calculation according to the step (a) are integrated to obtain the iron-loaded niobium pentoxide Fe oxide @ Nb₂O_5-zThe capacitance contribution in the lithium storage capacity reaches 89.1%, wherein the scanning rate in (a) is increased in the direction of the arrow;

FIG. 7 is the iron oxide-supported niobium pentoxide (Fe oxide @ Nb) prepared in example 1₂O_5-z) The weight change curve after full oxidation at 800 deg.c in air, whose formula z is 0.375 can be calculated from fig. 7 by measuring its added mass;

FIG. 8 is the iron oxide-supported niobium pentoxide (Fe oxide @ Nb) prepared in example 1₂O_5-z) Battery capacity measured by blue battery test system and Fe added in preparation reaction³⁺The relationship (a) of the ion concentration,and Fe element atomic ratio obtained by element quantitative analysis by using a scanning electron microscope and Fe in the preparation reaction³⁺Relation of ion concentration (b);

FIG. 9 is a scanning electron micrograph of an intermediate after solution reaction in the preparation of comparative example 1;

FIG. 10 is a graph of rate performance of a lithium ion battery made of a yellow iron oxide-supported orthorhombic niobium pentoxide material in comparative example 1;

FIG. 11 shows Fe oxide @ Nb obtained in example 1₂O_5-zThe aperture profile of (a).

Detailed Description

The present invention is further illustrated by the following examples, which are to be understood as merely illustrative and not restrictive.

The invention aims to provide a metal oxide material with high capacity, high rate capability and high stability and a preparation method thereof by combining the advantages of two materials, namely high-rate high-stability insertion type lithium storage and high-capacity conversion type lithium storage, aiming at the current situation that the current commercial battery is insufficient under the high-rate working condition.

In the present disclosure, the porous confinement multi-metal composite oxide material has a specific microstructure. The special microstructure consists in using a metal oxide (M) with a porous structure_xO_y-zX is more than or equal to 1 and less than or equal to 2, y is more than or equal to 1 and less than or equal to 5, and z is more than or equal to 0.1 and less than or equal to 0.9) is used as a matrix (also called as a carrier), and other metal oxides (A)_eO_fE is more than or equal to 1 and less than or equal to 3, f is more than or equal to 1 and less than or equal to 4) is adsorbed or directly grown in micropores and mesopores of the matrix, and has extremely small size under the action of confinement. Wherein, the particle size of the matrix is tens of nanometers to tens of micrometers (for example, 10 nm-50 μm), the crystal structure is an ordered single crystal, quasi-single crystal or twin crystal structure, the particles have less than five sets of electron diffraction spots and no obvious electron diffraction ring. And the matrix crystal contains disordered defects and hole structures, and the sizes of the defects and the holes are mainly distributed in mesopores with the aperture more than or equal to 2nm and less than or equal to 50nm and micropores with the aperture less than 2 nm. Particle size and porous confinement of multi-metal composite oxide material of matrixSubstantially identical. The obtained porous confined multi-metal composite oxide material has a specific surface area of tens to hundreds of square meters per gram, and the specific surface area is as high as 20-500 m²/g。

In the present invention, the multimetal oxide has mixed-valence metal elements. The general formula of the structure is A_eO_f@M_xO_y-zWherein A is selected from one or the combination of more than two of metal elements with conversion type or alloy type lithium storage mechanism such as manganese, iron, cobalt, nickel, copper, tin, zinc and the like, and M is selected from one or the combination of more than two of metal elements with intercalation type lithium storage mechanism such as niobium, molybdenum, titanium, vanadium, tungsten, zirconium, tantalum and the like. Wherein the atomic ratio of A is 0.1-20 at% (A is A)_eO_f@M_xO_y-zAtomic ratio of (d).

In the invention, by taking the reference of a mechanism of formation of a Cassier landform, a method for preparing the metal oxide material is disclosed, and a method for micro-etching alkali (earth) metal and transition metal composite oxide by micro-acid micro-pressure micro-etching is developed. In particular, the use of a multi-metal composite oxide N_nM_xO_yUsing acid solution dissolved with other metal element A as etching agent as precursor, adopting multi-step method to etch and dissolve all N ions and partial M ions in the precursor, and making a large number of defects and holes while maintaining structural order of crystal, at the same time utilizing high-temp. reaction environment to in-situ deposit element A in the acid solution on the surface of oxide and in the holes, after the etching reaction is completed, continuously supplementing high-temp. annealing (calcining) to prepare metal oxide supported by element A oxide and rich in defects and holes_eO_f@M_xO_y-z. Moreover, the chemical composition, specific morphology and crystal structure of the obtained product depend on the type and concentration of the element A in the acidic solution, the atomic composition and structure of the precursor and specific reaction conditions. The preparation method of the material avoids too fine regulation and control and a large amount of additives, and has the potential and value of industrial mass production.

The following is an exemplary description of the preparation of porous confined multi-metal composite oxide materials.

Preparation of Multi-element Metal composite oxide precursor N_aM_bO_cN is one or more of alkali metal, alkaline earth metal, lanthanum, aluminum and the like, and M is one or more of niobium, titanium, vanadium, tantalum, molybdenum, tungsten, zirconium and the like. Wherein a is more than or equal to 1 and less than or equal to 2, b is more than or equal to 1 and less than or equal to 8, and c is more than or equal to 3 and less than or equal to 17. The preparation method includes, but is not limited to, high temperature solid phase method, sol-gel method, hydrothermal synthesis method, coprecipitation method, etc.

Will N_aM_bO_cAnd mixing with an acidic solution containing A ions to obtain a mixed solution. Wherein A is one or more of metal elements such as manganese, iron, cobalt, nickel, copper, tin, chromium, zinc and the like. The precursor of the A ion can be one or more of soluble salts such as chloride, bromide, iodide, oxalate, nitrate, sulfate and the like, and is preferably the chloride of A. The acid in the acidic solution containing A ions can be one or more of hydrochloric acid, nitric acid, acetic acid, formic acid, ethylenediamine tetraacetic acid and the like, and hydrochloric acid is preferred. The solvent of the acidic solution containing the ion A is one or more of water, methanol, ethanol, ethylene glycol, propanol, acetone and the like, and water is preferred. The acidic solution containing A ions contains acid with the concentration of 1-50 times of the molar ratio of the precursor and the concentration of A ions with the molar ratio of 1-100 times of the molar ratio of the precursor. In other words, the multi-metal composite oxide N_aM_bO_cThe molar ratio to a ions may be 1: 1-1: 100, more preferably 1: 10. the molar ratio of the multi-metal composite oxide to the acid is 1: 1-1: between 50, preferably 1: 2. wherein, the concentration of A ions in the acid solution containing A ions can be 0.1-6 mol/L.

And synchronously carrying out corrosion reaction and deposition reaction on the mixed solution by adopting a multi-step method to prepare the porous confined multi-metal composite oxide material.

Firstly, heating the mixed solution to 50-90 ℃ at normal pressure, keeping for 1 hour-7 days to etch the surface layer of the multi-metal composite oxide and ions on the shallow surface layer, slowly dissolving out N ions near the surface layer by utilizing the acidity of the solution, and keeping the stability of the structure and the appearance. After filtration, the main phase of the particles 1 remains as the precursor, but the crystallinity is reduced. Among them, it is preferable to heat to 80 ℃ for 2 days.

Next, the particles 1 are added to an acidic solution containing a ions and mixed to obtain a mixed solution 2, since the concentration of the mixed solution 1 decreases with time, and the reaction proceeds with the aid of the original solution having a high concentration. Wherein, the acid solution containing A ions has the concentration of acid which is 1 to 50 times of the molar ratio of the precursor and the concentration of A ions which is 1 to 100 times of the molar ratio of the precursor. The concentration of A ions in the acidic solution containing A ions can be 0.1-6 mol/L. And transferring the mixed solution 2 into a high-temperature high-pressure reaction container, increasing the heat preservation temperature to 100-140 ℃, and preserving the heat for 1 hour-7 days to promote the dynamics of the etching reaction. After the reaction is finished, the particles 2 are obtained by filtering, and at this time, a small amount of products of the etching reaction appear in the particles 2, and the products are precursors and etching products. Preferably, the temperature is raised to 130 ℃ for 3 days.

Third, the particles 2 are added to the acidic solution containing the a ions and mixed to obtain a mixed solution 3, and the re-addition of the original solution is due to the decrease in the acid concentration of the mixed solution 2 under the long-term incubation reaction. Wherein, the acid solution containing A ions has the concentration of acid which is 1 to 50 times of the molar ratio of the precursor and the concentration of A ions which is 1 to 100 times of the molar ratio of the precursor. The concentration of A ions in the acidic solution containing A ions can be 0.1-6 mol/L. And finally, continuously increasing the reaction temperature of the mixed solution 3 to 150-220 ℃, preserving the heat for 1 hour to 7 days, further promoting the reaction kinetics, completely dissolving out the N element, forming holes on the surface and the bulk phase of the oxide, and simultaneously promoting the A element in the solution to be separated out and deposited on the surface and in the holes of the oxide at high temperature to obtain solid particles. Preferably, the temperature is increased to 160-200 ℃ and the temperature is kept for 3 days.

And (3) putting the solid particles in protective atmosphere such as inert atmosphere, nitrogen atmosphere or vacuum and the like for high-temperature annealing to obtain the porous limited-area multi-metal composite oxide material. Wherein the inert atmosphere is one or the combination of more than two of He, Ne and Ar. The annealing temperature is 400-1000 ℃, and the annealing time is 1-24 hours; preferably, the annealing temperature is 600 ℃ and the annealing time is 8 hours.

In the invention, the obtained porous confinement multi-metal composite oxide material with a special microstructure has the high rate and high stability of an embedded mechanism electrode material and the high capacity of an alloy type/conversion mechanism electrode material, can be used as an electrode material of an electrochemical energy storage device, and can be used for solving the problem of insufficient performance of a cathode material of electrochemical energy storage under the high rate working condition. On one hand, the existence of the mixed valence metal element M and oxygen vacancy greatly increases the electronic conductivity of the material; secondly, a large number of defects and multiple pores exist, so that the ion transmission property and the electrochemical activity of the material are improved, more lithium storable sites appear on the surface layer and the shallow surface layer, and the buffer can be provided for the volume change of the electrode in the working process; meanwhile, the high-capacity metal oxide material is loaded on the high-rate and high-stability metal oxide, and the respective points of the two materials are combined. The special microstructure provides guarantee for high power density and high stability of the material.

Sample characterization

The method comprises the steps of collecting morphology and ultrastructure information of a sample by using a scanning electron microscope and a transmission electron microscope, collecting sample structure information by using an X-ray diffractometer, collecting sample hole structure information by using a specific surface area tester, measuring sample conductivity by using a comprehensive physical property measuring system, and representing electrode performance of the sample by using a blue-ray battery testing system.

The present invention will be described in detail by way of examples. It is also to be understood that the following examples are illustrative of the present invention and are not to be construed as limiting the scope of the invention, and that certain insubstantial modifications and adaptations of the invention by those skilled in the art may be made in light of the above teachings. The specific process parameters and the like of the following examples are also only one example of suitable ranges, i.e., those skilled in the art can select the appropriate ranges through the description herein, and are not limited to the specific values exemplified below.

Example 1

LiNbO synthesized by a sol-gel method₃Adding FeCl dissolved with 10 times of molar ratio into the precursor₃And aqueous solution of HCl with 2 times of molar ratio, stirring and preserving the temperature for two days at 90 ℃. The particles 1 are filtered off and the above FeCl dissolved in a molar ratio of 10 times is added again₃(1.6mol/L) and a 2-fold molar ratio of HCl, and placing the mixed system in a high-temperature high-pressure reaction vessel to react for three days at 130 ℃. Filtering the particle 2, and finally adding FeCl dissolved with 10 times of molar ratio₃And 2 times of HCl aqueous solution, placing the mixed system in a high-temperature high-pressure reaction vessel, and reacting at 160 ℃ for three days to obtain an intermediate product. Dissolving out all lithium ions and part of niobium ions in the raw materials in the reaction by a hydrochloric acid solution, exchanging hydrogen ions in the hydrochloric acid solution to enter a crystal structure, separating out iron ions in the solution and depositing on the surface and in pore channels of the crystal, and filtering and separating precipitates in the solution under reduced pressure after the reaction is finished to obtain a yellow intermediate product, namely the iron oxide-loaded niobic acid particles Fe @ HNbO₃. Calcining the prepared niobic acid particles for 4 hours at 700 ℃ in an argon atmosphere to obtain black iron oxide (iron is mainly trivalent, and a small amount of Fe accounting for 1-5 percent of the total amount of Fe atoms can be reduced to be divalent) loaded monoclinic phase niobium pentoxide material, namely Fe oxide @ Nb₂O_5-zAnd z is 0.375. Fe oxide @ Nb₂O_5-zThe atomic proportion of Fe in the alloy is 10 at%. Resulting Fe oxide @ Nb₂O_5-zHas a specific surface area of about 61.2m²(ii) in terms of/g. See b in FIG. 8 when FeCl₃At concentrations of 0.16mol/L, 0.5mol/L and 0.8mol/L, respectively, the obtained Fe oxide @ Nb₂O_5-zThe atomic ratio of Fe in the alloy is 0.1 at%, 2.7 at% and 4.1 at%, respectively. Furthermore, with FeCl₃The concentration increases, the proportion of Fe atoms increases gradually, and the capacity of the lithium ion battery increases gradually, see a in FIG. 8. With respect to Fe oxide @ Nb obtained in example 1₂O_5-zUnless otherwise specified, the performance data are generally based on Fe oxide @ Nb with an Fe atomic ratio of 10 at%₂O_5-zAnd (3) obtaining the product.

From FIG. 1, it can be seen that Fe @ HNbO described using the present invention₃And Fe oxide @ Nb₂O_5-zA large number of defects and pores exist in the crystalFe oxide @ Nb of final product₂O_5-zThe particle size is about 50 nanometers, the structure is ordered to be single crystal, disordered defects and holes exist in the crystal, the pore size distribution analysis is shown in figure 11, and the particle size distribution is mostly concentrated below 2nm and is 20-30 nm. (ii) a The LiNbO precursor can be seen by comparing the X-ray diffraction pattern in FIG. 2 with the XRD standard card of the corresponding substance₃And etching reaction to obtain Fe @ HNbO₃And the final product Fe oxide @ Nb₂O_5-z(ii) a In FIG. 3 a is shown Fe oxide @ Nb₂O_5-zLinear voltammetric sweep curve of (1) and calculating Fe oxide @ Nb based on the method₂O_5-zAnd comparative sample Nb₂O₅The conductivity of the two can be seen in fig. 3 b, and the comparison of the conductivities of the two can be seen, and it is found that the Fe oxide @ Nb produced using the process of the invention₂O_5-zThe conductivity is compared with that of Nb prepared by a sol-gel method₂O₅The conductivity is improved by hundreds of times 400x, and the improvement of the conductivity is very beneficial to the exertion of excellent electrochemical energy storage capacity; as can be seen in FIG. 4, the multiplying power performance of the iron oxide-supported niobium pentoxide prepared by the method described in the invention is greatly improved and reaches (0.5C:347mA h g)^-1，25C:307mA h g^-1，100C:248mA h g^-1) Is superior to high-power negative electrode materials of lithium ion batteries.

Example 2

LiNbO synthesized by a sol-gel method₃Adding and dissolving 5 times of Cr in molar ratio³⁺3 times of hydrochloric acid aqueous solution, stirring at 80 ℃ and keeping the temperature for two days. Filtering the particles 1, and adding the dissolved Cr with 5 times of mol ratio again³⁺(0.8mol/L) and a 3-fold molar ratio of HCl, and placing the mixed system in a high-temperature high-pressure reaction vessel to react for three days at 110 ℃. Filtering the particle 2, and finally adding the Cr dissolved with 5 times of the mol ratio³⁺And 3 times of HCl aqueous solution, placing the mixed system in a high-temperature high-pressure reaction vessel, and reacting for five days at 150 ℃ to obtain an intermediate product. During the reaction, all lithium ions and part of niobium ions in the raw materials are dissolved out by the solution, hydrogen ions in the solution are exchanged into a crystal structure, chromium ions in the solution are precipitated and deposited on oxide particles, and after the reaction is finished, the oxide particles are subjected to the reactionFiltering and separating the precipitate in the solution under reduced pressure to obtain a green intermediate product, namely the chromium-loaded niobic acid particles Cr @ HNbO₃. The prepared niobic acid particles were calcined at 800 ℃ for 4 hours under an argon atmosphere. To obtain chromium oxide (Cr)₂O₃) Supported monoclinic phase niobium pentoxide material, i.e. Cr oxide @ Nb₂O_5-zWherein z is 0.45. Cr oxide @ Nb₂O_5-zThe atomic ratio of medium Cr is 4.8 at%. Resulting Cr oxide @ Nb₂O_5-zHas a specific surface area of about 42.5m²/g。

Example 3

SrMoO synthesized by sol-gel method₄Adding Fe dissolved with 5 times of mol ratio ³⁺1 times molar ratio of HCl in water, stirred at 80 ℃ and incubated for two days. Filtering the particles, and adding the dissolved Fe with 5 times of mol ratio³⁺(0.5mol/L) and 1 time molar ratio of HCl aqueous solution, and placing the mixed system in a high-temperature high-pressure reaction vessel for reacting for three days at 110 ℃. Filtering the granules, and adding the dissolved Fe with 5 times of mol ratio³⁺And HCl aqueous solution with the molar ratio of 1 time, placing the mixed system in a high-temperature high-pressure reaction vessel, and reacting for three days at 200 ℃ to obtain an intermediate product. During the reaction, all strontium ions and part of molybdenum ions in the raw materials are dissolved out by hydrochloric acid solution, iron ions in the solution are separated out and deposited on oxide particles, and after the reaction is finished, the precipitate in the solution is separated by reduced pressure filtration, so that molybdenum oxide particles with amorphous structures as yellow intermediate products are obtained. The resulting particles were calcined in vacuo at 600 ℃ for 4 hours. To obtain Fe oxide (mainly trivalent Fe, a small amount of about 1-5% Fe is reduced to divalent) @ MoO_3-z. Fe oxide @ MoO_3-zThe atomic ratio of Fe in the alloy is 7.1 at%. Resulting Fe oxide @ MoO_3-zHas a specific surface area of about 48.2m²/g。

Example 4

The high-temperature solid phase method is used for synthesizing K₂TiO₃Adding Fe dissolved with 5 times of mol ratio³⁺1-fold molar ratio of HNO₃The aqueous solution of (a) was stirred at 90 ℃ and incubated for three days. Filtering the particle 1, and adding the dissolved Fe with 5 times of mol ratio again³⁺(0.7mol/L) and 1-fold molar ratio of HNO₃Aqueous solution of (A)And placing the mixed system in a high-temperature high-pressure reaction vessel for reaction at 140 ℃ for three days. Filtering the granules 2, and finally adding the dissolved Fe with 5 times of mol ratio³⁺1-fold molar ratio of HNO₃The mixed system is placed in a high-temperature high-pressure reaction vessel, and the intermediate product can be obtained after reaction for three days at the temperature of 200 ℃. During the reaction, all potassium ions and part of titanium ions in the raw materials are dissolved out by nitric acid solution, iron ions in the solution are precipitated and deposited on oxide particles, and after the reaction is finished, the precipitates in the solution are separated by reduced pressure filtration to obtain titanium oxide particles with amorphous structures as yellow intermediate products. The resulting particles were calcined in vacuo at 600 ℃ for 4 hours. To obtain an iron oxide (mainly trivalent Fe, with a small amount of about 1-5% Fe reduced to divalent) loaded titanium dioxide material, i.e., Fe oxide @ TiO_2-z. Fe oxide @ TiO_2-zThe atomic ratio of Fe in the alloy is 3.2 at%. The resulting Fe oxide @ TiO_2-zHas a specific surface area of about 80.5m²/g。

Example 5

SrTiO synthesized by high-temperature solid phase method₃Adding CoCl dissolved with 5 times of molar ratio ₂2 times of HCl in ethanol, stirred at 60 ℃ and kept warm for three days. The particles 1 are filtered off and the above solution is reintroduced with CoCl in a molar ratio 5 times that of the solution₂(0.6mol/L) and 2 times of HCl in ethanol, and placing the mixed system in a high-temperature high-pressure reaction vessel to react for three days at 120 ℃. Filtering the particle 2, and finally adding the CoCl dissolved with 5 times of mol ratio₂And 2 times of HCl ethanol solution, placing the mixed system in a high-temperature high-pressure reaction vessel, and reacting at 150 ℃ for three days to obtain an intermediate product. During the reaction, strontium ions in the raw material are dissolved out by the solution, cobalt ions in the solution are precipitated and deposited on oxide particles, and after the reaction is finished, the precipitate is separated by reduced pressure filtration to obtain titanium oxide particles of which pink intermediate product is rutile phase. The resulting pellets were calcined under argon at 700 ℃ for 4 hours. Obtaining a cobalt oxide-supported titanium dioxide material, i.e. Co oxide @ TiO_2-zAnd z is 0.61. Co oxide @ TiO_2-zThe atomic ratio of Co in the alloy is 2.8 at%. Resulting Co oxide @ TiO_2-zHas a specific surface area of about 46.7m²/g。

Example 6

The high-temperature solid phase method is used for synthesizing K₂Ti₈O₁₇Adding dissolved NiCl with 2 times of molar ratio ₂2 times of HCl in ethanol, stirred at 60 ℃ and kept warm for three days. The granulate 1 is filtered off and 5-fold molar NiCl is added again₂(0.16mol/L) and 2 times of HCl in ethanol, and placing the mixed system in a high-temperature high-pressure reaction vessel to react for three days at 130 ℃. Then, the mixture was filtered to obtain granules 2. Finally, the particles 2 are added into the NiCl dissolved with 5 times of mol ratio₂And 2 times of HCl ethanol solution, placing the mixed system in a high-temperature high-pressure reaction vessel, and reacting at 180 ℃ for three days to obtain an intermediate product. During the reaction, potassium ions in the raw materials are dissolved out by the solution, nickel ions in the solution are separated out and deposited on oxide particles, and after the reaction is finished, the precipitate is separated by reduced pressure filtration to obtain titanium oxide particles of which the green intermediate product is an anatase phase. The solid particles obtained were calcined under argon at 500 ℃ for 4 hours. To obtain Ni oxide @ TiO_2-zAnd z is 0.52. Ni oxide (NiO) @ TiO_2-zWherein the atomic ratio of Ni is 4 at%. Resulting Ni oxide @ TiO_2-zHas a specific surface area of about 80.7m²/g。

Experimental example 7:

in this experimental example 7, a lithium ion battery was fabricated using the iron-supported niobium pentoxide material prepared in example 1, and an electrochemical performance test was performed.

The iron oxide-supported niobium pentoxide material prepared in example 1, acetylene black and polyvinylidene fluoride in a mass ratio of 8: 1: 1 preparing slurry, uniformly coating the slurry on a copper foil, drying, cutting a circular electrode plate, taking the circular electrode plate as a positive electrode, taking a metal lithium plate as a negative electrode, and taking the concentration of the lithium plate as 1mol L^-1LiPF of₆The solution (the solvent is a mixed solvent consisting of ethylene carbonate, diethyl carbonate and dimethyl carbonate in a mass ratio of 1: 1: 1) is used as an electrolyte, the Whatman porous polypropylene membrane is used as a film, and the button lithium ion battery is assembled by using a CR2016 battery shell.

The button type lithium ion battery prepared by taking the iron oxide-supported niobium pentoxide material of the embodiment 1 as the anode has the charge-discharge voltage range of 1-3V and the temperature of 20 +/-5 DEG CAnd (3) carrying out rate charge and discharge performance test and long-time cycle performance test under the condition. The results of the performance tests and the comparison with the comparative sample are shown in figure 4. The rate capability can be seen: 0.5C:347mA h g^-1，25C:307mA h g^-1，100C:248mA h g^-1And excellent capacity retention rate under rapid charge and discharge. The high rate performance is superior to most cathode materials.

Experimental example 8:

in this experimental example 8, a lithium ion battery was fabricated using the chromium oxide-supported niobium pentoxide material prepared in example 2, and an electrochemical performance test was performed.

The chromium oxide supported niobium pentoxide material prepared in example 2, acetylene black and polyvinylidene fluoride were mixed in a mass ratio of 8: 1: 1 preparing slurry, uniformly coating the slurry on a copper foil, drying, cutting a circular electrode plate, taking the circular electrode plate as a positive electrode, taking a metal lithium plate as a negative electrode, and taking the concentration of the lithium plate as 1mol L^-1LiPF of₆The solution (the solvent is a mixed solvent consisting of ethylene carbonate, diethyl carbonate and dimethyl carbonate in a mass ratio of 1: 1: 1) is used as an electrolyte, the Whatman porous polypropylene membrane is used as a film, and the button lithium ion battery is assembled by using a CR2016 battery shell.

The lithium has specific capacity as high as 331mAh/g, which is far superior to Nb⁴⁺/Nb⁵⁺Theoretical limit value of 200mA h g^-1And Li₄Ti₅O₁₂175mA h g of^-1。208mA h g^-1@100C、136mA h g^-1@250C, capacity and rate performance far superior to that of no-load Nb₂O_5-zAnd common rate type electrode material Li₄Ti₅O₁₂. The rate performance at 5C and 10C is compared with that of a common cathode material as shown in figure 5.

Comparative example 1

LiNbO synthesized by the sol-gel method in comparative example 1₃Adding FeCl dissolved with 10 times of molar ratio into the precursor₃(1.6mol/L) and aqueous solution of HCl with 2 times of molar ratio, keeping the temperature for 90 ℃ for two days while stirring, then placing the mixture into a high-temperature high-pressure reaction vessel, reacting for three days at 130 ℃, and continuously heating to 160 ℃ for reacting for three days to obtain an intermediate product. In this case, the intermediate product was not contained as in example 1The structure is a porous single crystal structure, and the monoclinic phase niobium pentoxide with the size of about 30-50nm generates orthorhombic phase niobium pentoxide with regular hexagonal morphology, and the morphology is shown in figure 9. This is due to the particular mechanism of the reaction. Specifically, in example 1, a solution with a higher concentration was added at the beginning of the three-step solution reaction, and the higher acid concentration ensured that Li ions in the precursor were continuously dissolved out from the surface layer to the inside of the crystal in the three-step reaction, and finally the structure of the porous single crystal was obtained. In comparative example 1, however, a high-concentration solution was added only at the beginning of the first solution reaction, and the acidity of the solution gradually decreased with the reaction time, so that the Li in the original precursor was prevented from being continuously dissolved out, and finally the reaction kinetics of Li dissolution in the third high-temperature reaction was unfavorable, which became the dissolution-recrystallization process of the precursor. The orthorhombic niobium pentoxide crystal with greatly changed appearance and over hundred-fold (about 10 mu m) increased size is formed, and the crystal has no porous structure, and iron ions are deposited on the surface of the crystal. Finally, calcining the prepared solid particles for 4 hours at 700 ℃ in an argon atmosphere to obtain a yellow iron oxide-supported orthorhombic niobium pentoxide material, namely Fe oxide @ Nb₂O₅(non-oxygen deficient niobium oxide) with a specific surface area of only 15.1m²(ii) in terms of/g. Since no new acid solution containing A ions is added after the reaction in each step is completed, the obtained material is a product of the dissolution-recrystallization process, and is a non-porous niobium pentoxide crystal with a regular morphology, and the iron oxide is simply loaded on the surface of the niobium pentoxide crystal rather than in the pores, so that the performance is poor, as shown in FIG. 10. See example 7 for a procedure for making a lithium ion battery of this comparative example 1.

Claims

1. The porous confined multi-metal composite oxide material is characterized in that the structural general formula of the porous confined multi-metal composite oxide material is A_eO_f@M_xO_{y z-}(ii) a The M is_xO_{y z-}Is an ordered mono-, quasi-mono-, or twin-crystal structure, has a porous structure, and A_eO_fConfinement deposition at M_xO_{y z-}Forming a composite structure among the porous structures; x is more than or equal to 1 and less than or equal to 2, y is more than or equal to 1 and less than or equal to 5, z is more than or equal to 0.1 and less than or equal to 0.9, e is more than or equal to 1 and less than or equal to 3, and f is more than or equal to 1 and less than or equal to 4;

2. The porous confinement multi-metal composite oxide material of claim 1, wherein M is selected from the group consisting of_xO_{y z-}The porous structure comprises mesopores with the aperture of more than or equal to 2nm and less than or equal to 50nm and micropores with the aperture of less than 2 nm; preferably, the aperture of the mesopores is 30-40 nm, and the aperture of the micropores is more than or equal to 1nm and less than 2 nm.

3. The porous confinement multimetal composite oxide material according to claim 1 or 2, wherein the atomic proportion of A is 0.1 to 20 at%.

4. The porous confined multi-metal composite oxide material according to any one of claims 1 to 3, wherein the size of the porous confined multi-metal composite oxide material is 10nm to 50 μm.

5. A method for preparing a porous, confined, multi-metal composite oxide material according to any one of claims 1 to 4, comprising:

6. The method according to claim 5, wherein the acid in the acidic solution containing A ions is at least one of hydrochloric acid, nitric acid, acetic acid, hydroiodic acid, hydrobromic acid, formic acid, and ethylenediaminetetraacetic acid; the precursor of the A ion is at least one of chloride of the A element, bromide of the A element, iodide of the A element, oxalate of the A element, nitrate of the A element and sulfate of the A element.

7. The production method according to claim 5 or 6, wherein in the step (1), the molar content of A ions in the acidic solution containing A ions is the precursor N of the multi-metal composite oxide_aM_bO_c1 to 100 times, preferably 2 to 10 times; the molar content of acid in the acidic solution containing the A ions is the precursor N of the multi-element metal composite oxide_aM_bO_c1 to 50 times, preferably 1 to 3 times; the concentration of the A ions in the acidic solution containing the A ions is 0.1-6 mol/L.

8. The method according to claim 7, wherein in the step (3), the molar content of A ions in the acidic solution containing A ions is the precursor N of the multi-metal composite oxide_aM_bO_c1 to 100 times, preferably 2 to 10 times, and the molar content of the acid is the multi-metal composite oxide precursor N_aM_bO_c1-50 times, preferably 1-3 times, and the concentration of A ions in the acidic solution containing A ions is 0.1-6 mol/L; in the step (4), the molar content of A ions in the acidic solution containing A ions is N, which is a precursor of the multi-metal composite oxide_aM_bO_c1 to 100 times, preferably 2 to 10 times, and the molar content of the acid is the multi-metal composite oxide precursor N_aM_bO_c1 to 50 times, preferably 1 to 3 times, and the concentration of the A ions in the acidic solution containing the A ions is 0.1 to 6 mol/L.

9. The production method according to any one of claims 5 to 8, wherein in step (5), the protective atmosphere is a vacuum atmosphere, an inert atmosphere, or a nitrogen atmosphere; the inert atmosphere is at least one of He, Ne and Ar.

10. Use of the porous confined multi-metal composite oxide material according to any one of claims 1 to 4 as an electrode material for an electrochemical energy storage device.