Preparation method and application of metal oxide positive electrode modified by atomic layer deposition technology

Abstract

The present invention discloses a method for preparing a metal oxide positive electrode modified by atomic layer deposition technology. By using the atomic layer deposition technology and controlling the type of reaction source, the cobalt-doped Ti3C2Tx-coated HNaV6O 16 ·4H2O composite powder surface successfully deposited Al2O3, Fe2O3, ZnO, TiO2 and other metal oxides; the present invention also discloses a method for preparing a metal oxide positive electrode modified by atomic layer deposition technology, the prepared metal oxide combined with Ti3C2Tx coating and synergistically doped with Co HNaV6O 16 ·4H2O is used in lithium / sodium ion batteries. The deposited metal oxide coating effectively inhibits the volume expansion of the material during the charge and discharge process and reduces the occurrence of side reactions of the electrolyte on the active material, thereby improving the charge and discharge efficiency and cycle stability of the positive electrode material.

Description

Technical Field

[0001] The invention belongs to the technical field of powders of composite layered metal oxide positive electrode materials modified by atomic layer deposition technology, and relates to a method for preparing a metal oxide positive electrode modified by atomic layer deposition technology.

[0002] The present invention also relates to a method for preparing a metal oxide positive electrode modified by atomic layer deposition technology, a metal oxide combined with Ti 3 C 2 Tx coating synergistically with Co-doped HNaV 6 O 16 ·4H 2 Application of O in lithium / sodium ion batteries. Background Art

[0003] Energy conversion and storage have become key issues of concern in our daily lives. In terms of energy density, the most suitable form of energy storage is chemical energy, especially the most mature secondary battery energy storage technology. Batteries can provide stored chemical energy, which has the ability to convert into electrical energy with high efficiency and no gaseous emissions. Therefore, researchers are increasingly interested in low-cost, safe and rechargeable batteries with sufficient voltage, capacity and rate capabilities. High-energy lithium-ion batteries for portable electronic devices have become an indispensable part of our lives. When it comes to large-scale power systems, the focus of research shifts to production costs. However, the demand for high-capacity energy systems continues to rise, resulting in a sharp increase in lithium costs, and the global lithium reserves are limited and unevenly distributed. These characteristics will restrict the application of lithium-ion batteries in smart grids and large-scale energy storage that require low prices and high safety. In contrast to lithium, sodium resources are abundant. Sodium and lithium are located in the same main group of the periodic table and have similar physical and chemical properties. Although the radius of sodium ions is slightly larger than that of lithium ions, as long as suitable positive and negative battery materials are found, sodium ion batteries can also show excellent electrochemical properties.

[0004] At present, the key point of the development and commercialization of sodium-ion batteries lies in the lack of cathode materials with excellent performance; therefore, the development and research of suitable cathode materials is an important topic in the current research of sodium-ion batteries; the cathode materials of layered oxides are the most concerned topic in the research of sodium-ion batteries. The widely studied cathode materials are mainly layered vanadium-based oxides. Due to their diverse structures and layered structures, the high specific capacity they exhibit can be attributed to the large interlayer spacing that provides channels for the diffusion of sodium ions; in addition, V with high oxidation valence 5+ First restore to V 4+ , and then further reduced to a lower oxidation state. This valence change capacity can accommodate a large amount of Na + As one of the vanadium-based oxides, HNaV 6 O 16·4H 2 O is composed of VO 6 Octahedron and VO 5 The trigonal bipyramids share oxygen atoms to form a [V 3 O 8 ] unit, Na + It is located at [V 3 O 8 ] plays a supporting role in the interlayer gap position and stabilizes the crystal structure. It is a sodium electric material with great development potential; however, its low electronic conductivity and slow sodium ion diffusion rate lead to rapid capacity decay and poor rate performance during the cycle. In this study, we used a general hydrothermal method to achieve a small amount of cobalt ions in HNaV 6 O 16 ·4H 2 Chemical embedding between O layers can effectively improve HNaV 6 O 16 ·4H 2 O ion diffusion kinetics, electronic conductivity and structural stability, thereby improving the electrochemical performance. On this basis, Co was embedded in HNaV by electrostatic self-assembly. 6 O 16 ·4H 2 O surface is successfully coated with a small amount of Ti 3 C 2 Tx, inhibition of HNaV 6 O 16 ·4H 2 O due to the dissolution of V caused by the structural decay problem; on this basis, the present invention uses atomic layer deposition technology through atomic-level fine control to successfully 3 C 2 Tx@Co-HNaV 6 O 16 ·4H 2 A metal oxide nanolayer of a certain thickness is uniformly deposited on the surface of the O powder. The metal oxide nanolayer can not only effectively reduce the corrosion of HF on the positive electrode material and enhance the initial coulombic efficiency, but also the metal oxide coating layer can effectively inhibit the structural collapse caused by volume expansion during the charge and discharge process, greatly enhancing the cycle stability of the positive electrode material and bringing a good improvement effect. Summary of the invention

[0005] The purpose of the present invention is to provide a method for preparing a metal oxide positive electrode modified by atomic layer deposition technology, which solves the problems of severe corrosion of HF to positive electrode materials and structural collapse existing in the prior art.

[0006] The technical solution adopted by the present invention is a method for preparing a metal oxide positive electrode modified by atomic layer deposition technology, which specifically comprises the following steps:

[0007] Step 1, weighing vanadium oxyphosphate monohydrate, dispersing it in deionized water and ultrasonically treating it to obtain solution A;

[0008] Step 2, weighing cobalt acetate tetrahydrate and anhydrous sodium iodide and adding them to solution A to obtain solution B;

[0009] Step 3, subjecting solution B to ultrasonic treatment;

[0010] Step 4, pour the ultrasonicated solution B into the inner lining of the reaction kettle, then fix the inner lining in the outer kettle, put it into a forced air drying oven for drying, and then wash it;

[0011] Step 5, vacuum drying and collecting the product, grinding to obtain cobalt-doped HNaV 6 O 16 ·4H 2 O powder sample;

[0012] Step 6: HNaV 6 O 16 ·4H 2 O was added to the CTAB aqueous solution and stirred continuously to obtain solution C;

[0013] Step 7: Add solution C to Ti 3 C 2 In the beaker of Tx suspension, stirring was continued to obtain solution D;

[0014] Step 8: vacuum filter the solution D, wash and dry it to obtain the cobalt-doped Ti 3 C 2 Tx-coated HNaV 6 O 16 ·4H 2 O powder sample;

[0015] Step 9, placing the powder obtained in step 8 into an ALD reaction chamber, evacuating the chamber and heating the chamber;

[0016] Step 10, in a vacuum environment, inert gas carries TMA vapor and deposits it on the cobalt-doped Ti 3 C 2 Tx-coated HNaV 6 O 16 ·4H 2 O particle surface;

[0017] Step 11, the inert carrier gas at a specific flow rate will dope the cobalt with Ti 3 C 2 Tx-coated HNaV 6 O 16 ·4H 2 The physically adsorbed TMA on the surface of O particles is blown off, leaving a layer of chemically adsorbed TMA;

[0018] Step 12: Water generates steam pressure by itself and cobalt doping synergistically with Ti 3 C 2 Tx-coated HNaV 6 O 16 ·4H 2 TMA adsorbed on the surface of O particles undergoes redox reaction;

[0019] Step 13, the inert carrier gas at a specific flow rate will dope the cobalt with Ti 3 C 2 Tx-coated HNaV 6 O 16 ·4H 2 The byproducts and excess water molecules on the surface of the O particles are blown off the surface; after standing, the chamber is purged with inert gas to complete an ALD cycle. Multiple cycles are performed under the same deposition conditions to complete the specified thickness of Al 2 O 3 of deposition.

[0020] The present invention is also characterized in that:

[0021] Step 1 specifically comprises: dispersing 250-350 mg of monohydrated vanadium oxyphosphate into 30-40 ml of deionized water, and ultrasonically treating for 0.5 h to 1.5 h at an ultrasonic power of 80-120 W at room temperature;

[0022] Step 2 specifically comprises: weighing 15-16 mg of cobalt acetate tetrahydrate and 90-95 mg of anhydrous sodium iodide and adding them to solution A, wherein the cobalt acetate tetrahydrate is micro-adjusted and the weighing instrument is an analytical balance;

[0023] In step 3, the ultrasonic wave is applied for 1 h to 3 h at a power of 80 to 120 W at room temperature until the solution gradually changes from wine red to black;

[0024] Wherein the drying temperature in step 4 is 140-160°C, the reaction time is 11-13h, and the washing process is: washing with water 2-4 times and alcohol 2-4 times alternately, the water and alcohol alternate washing is mainly carried out by suction filtration or centrifugation, and the collection is also mainly carried out by suction filtration or centrifugation;

[0025] In step 5, the vacuum drying condition is 50-70° C., and the drying time is 11-13 hours. Before vacuum drying, the product is sealed with a plastic wrap, and then the plastic wrap is pierced to ensure that it is fully dried under low pressure conditions.

[0026] Step 6 specifically comprises: adding 0.4-0.6 g of HNaV 6 O 16 ·4H 2O particles are added to 2.0-3.0 ml of 1.0-1.5 mg / ml CTAB aqueous solution, and stirred continuously for 20-40 min at a stirring speed of 400-600 r / min to obtain solution C;

[0027] Step 7 is as follows: drip solution C into a 3 C 2 The Tx suspension was stirred in a beaker for 20 to 40 minutes at a speed of 400 to 600 r / min to obtain solution D.

[0028] The cleaning and drying process in step 8 is as follows: washing with deionized water for 2 to 4 times to remove CTAB, and then vacuum drying and collecting the product, the vacuum drying conditions are 50 to 70° C., and drying for 11 to 13 hours. Before vacuum drying, the product is sealed with a plastic wrap, and then the plastic wrap is pierced to ensure that it is fully dried under low pressure conditions;

[0029] In step 9, before the powder is placed in the ALD reaction chamber, the powder is vibrated and dispersed, and the temperature is raised to 110-130° C. under vacuum;

[0030] In step 10, the inert gas flow rate is 40 ml / min, the duration is 50 to 70 s, and the reaction steam source can be TMA, DEZ, Fe(cp) 2 、TiCl 4 wait;

[0031] Wherein the inert gas flow rate in step 11 is 80 ml / min, and the blowing time is 110 to 130 s;

[0032] In step 12, the water injection time is 60 seconds;

[0033] In step 13, the inert gas flow rate is 80 ml / min, and the duration is 110 to 130 s;

[0034] The second technical solution adopted by the present invention is that the metal oxide prepared by the preparation method of the metal oxide positive electrode modified by atomic layer deposition technology is combined with Ti 3 C 2 Tx coating synergistically with Co-doped HNaV 6 O 16 ·4H 2 Application of O in lithium / sodium ion batteries.

[0035] The beneficial effects of the present invention are:

[0036] (1) Since the present invention adopts a one-step hydrothermal reaction to directly synthesize the initial target powder, it has a low synthesis temperature and a simple synthesis path, and does not require large equipment and harsh reaction conditions;

[0037] (2) The vanadium source and phosphorus source used in the present invention are vanadium oxyphosphate monohydrate, the sodium source is anhydrous sodium iodide, and the solvent is deionized water. These three substances are common raw materials, cheap and easy to obtain, and low in cost. The entire reaction is easy to control and environmentally friendly, and the product does not require post-processing, which is suitable for large-scale production;

[0038] (3) Ti selected by the present invention 3 C 2 Tx powder is easy to etch and synthesize, the process is mature, and the operation is simple and convenient;

[0039] (4) The atomic layer deposition technology used in the present invention finely controls the thickness of metal oxides at the atomic scale, and the technology is mature and has strong repeatability;

[0040] (5) The present invention strictly coordinates and controls the concentration and ratio of the vanadium source, sodium source and cobalt salt, reaction temperature, reaction time and other parameters to fully utilize the reaction of the vanadium source, sodium source and cobalt source, so that the cobalt ions are successfully embedded in HNaV 6 O 16 ·4H 2 O nucleates and grows uniformly in deionized water, producing a petal structure of about 5 μm in size assembled by nanosheets with a width of about 400 nm and a thickness of about 5 nm;

[0041] (5) Effect of cobalt salt addition on cobalt-doped HNaV 6 O 16 ·4H 2 The degree of structural order of O has a great influence on the performance of the synthesized product as a cathode material for sodium ion batteries.

[0042] (6) Effect of reaction time and temperature on the HNaV intercalation of cobalt ions 6 O 16 ·4H 2 O plays a key role in the growth of HNaV. Too long or too short reaction time, too high or too low reaction temperature are not conducive to the assembly of a good micro-flower structure and directly affect the 6 O 16 ·4H 2 Performance of O as a cathode material for sodium-ion batteries;

[0043] (7) Cobalt ion embedding into HNaV 6 O 16 ·4H 2 During the in-situ growth of O, the synergistic effect of the temperature field and pressure field generated by hydrothermal heat causes cobalt ions to 6 O 16 ·4H 2 Strong chemical bonds are formed between O layers and they always exist stably between the layers during the charge and discharge process;

[0044] (8)Ti 3 C 2 The Tx coating layer is tightly coated on the cobalt-doped HNaV by electrostatic coupling. 6 O 16 ·4H 2 O lattice surface, effectively inhibiting the electrolyte from reacting with HNaV 6 O 16 ·4H 2 O corrosion and vanadium dissolution reduce capacity loss and significantly improve structural stability;

[0045] (9) The atomic layer deposition technology used in the present invention can successfully achieve the cobalt-doped Ti 3 C 2 Tx coated HNaV 6 O 16 ·4H 2 Al was successfully deposited on the surface of O composite powder 2 O 3 , Fe 2 O 3 , ZnO, TiO 2 The deposited metal oxide coating effectively inhibits the volume expansion of the material during the charge and discharge process, and reduces the occurrence of side reactions of the electrolyte to the active material, thereby improving the charge and discharge efficiency and cycle stability of the positive electrode material;

[0046] (10) The product prepared by the present invention can show good performance when used as a positive electrode material for sodium ion batteries. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 This is the X-ray diffraction pattern of the product prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0048] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0049] The present invention provides a method for preparing a metal oxide positive electrode modified by atomic layer deposition technology, the purpose of which is to obtain a metal oxide combined with Ti by using atomic layer deposition technology. 3 C 2 Tx coating synergistically with Co-doped HNaV 6 O 16 ·4H 2 O composite powder, using water as solvent, anhydrous sodium iodide and monohydrated vanadium oxyphosphate as sodium source and vanadium source, by synergistically controlling their concentration and ratio, reaction temperature, reaction time, filling ratio and other parameters, the first one-step hydrothermal synthesis of HNaV2 assembled by nanosheets and embedded with cobalt ions was achieved.6 O 16 ·4H 2 O powder; on this basis, CTAB was used to etch the Ti 3 C 2 Tx and HNaV 6 O 16 ·4H 2 O was composited by electrostatic coupling and finally successfully prepared Co-doped synergistic Ti 3 C 2 Tx-coated HNaV 6 O 16 ·4H 2 O powder; on this basis, the atomic layer deposition technology was used to dope Co with Ti 3 C 2 Tx-coated HNaV 6 O 16 ·4H 2 O powder was used to prepare an ultra-thin metal oxide layer of specified thickness at the nanometer level, and finally a metal oxide combined with Ti was successfully prepared. 3 C 2 Tx coating synergistically with Co-doped HNaV 6 O 16 ·4H 2 O composite powder, when the above product is applied to the positive electrode material of lithium / sodium ion battery, it can show excellent electrochemical performance; in the preparation method of the present invention, the metal oxide and cobalt doping synergistically Ti 3 C 2 Tx-coated HNaV 6 O 16 ·4H 2 The bond between O is chemical bond, not physical bond;

[0050] The present invention also provides a method for depositing metal oxides followed by cobalt doping and Ti 3 C 2 Tx-coated HNaV 6 O 16 ·4H 2 The application of O composite powder can be in the field of lithium / sodium ion batteries.

[0051] Example 1

[0052] Step 1, weigh 300 mg of vanadium oxyphosphate monohydrate, disperse it in 35 ml of deionized water, and ultrasonicate for 1 hour to obtain solution A;

[0053] Step 2, weighing 15.8 mg of cobalt acetate tetrahydrate and 92.80 mg of anhydrous sodium iodide, and adding them to solution A to obtain solution B;

[0054] Step 3, sonicate solution B for 2 h, and the solution gradually changes from wine red to black;

[0055] Step 4, pour the ultrasonicated solution B into the 50 ml reactor liner, then fix the liner in the outer reactor, put it into a forced air drying oven, react at 150° C. for 12 h, and wash the product with water and alcohol alternately for 3 times;

[0056] Step 5, vacuum drying and collecting the product, grinding to obtain cobalt-doped HNaV 6 O 16 ·4H 2 O powder sample;

[0057] Step 6, 0.5 g of HNaV 6 O 16 ·4H 2 O particles were added to 2.5 ml of 1.2 mg / ml CTAB aqueous solution and stirred for 30 min to obtain solution C;

[0058] Step 7: Add solution C dropwise into the 9 ml Ti 3 C 2 The Tx suspension was placed in a beaker and stirred for 30 min to obtain solution D;

[0059] Step 8: vacuum filter the solution D, wash it with deionized water for 3 times to remove CTAB, and then vacuum dry the collected product to obtain cobalt-doped Ti 3 C 2 Tx-coated HNaV 6 O 16 ·4H 2 O powder sample;

[0060] Step 9: Cobalt doping with Ti 3 C 2 Tx-coated HNaV 6 O 16 ·4H 2 O powder is placed in the ALD reaction chamber, evacuated and heated to 110-130°C;

[0061] Step 10, in a vacuum environment, inert gas carries TMA vapor and deposits it on the cobalt-doped Ti 3 C 2 Tx-coated HNaV 6 O 16 ·4H 2 O particle surface, duration 60s;

[0062] Step 11, the inert carrier gas at a specific flow rate will dope the cobalt with Ti 3 C 2Tx-coated HNaV 6 O 16 ·4H 2 The physically adsorbed TMA on the surface of O particles was blown off, leaving a layer of chemically adsorbed TMA. The blowing time was 120 s.

[0063] Step 12: Water generates steam pressure by itself and cobalt doping synergistically with Ti 3 C 2 Tx-coated HNaV 6 O 16 ·4H 2 TMA adsorbed on the surface of O particles undergoes redox reaction;

[0064] Step 13, the inert carrier gas at a specific flow rate will dope the cobalt with Ti 3 C 2 Tx-coated HNaV 6 O 16 ·4H 2 The byproducts and excess water molecules on the surface of the O particles were blown away from the surface. The flow time was 120s. After standing still, the chamber was purged with inert gas to complete an ALD cycle. Multiple cycles were performed under the same deposition conditions to complete the specified thickness of Al 2 O 3 of deposition.

[0065] like Figure 1 As shown, all diffraction peaks can be well matched with HNaV 6 O 16 ·4H 2 O standard card PDF#49-0996; Due to the low content of introduced cobalt ions, HNaV 6 O 16 ·4H 2 The crystal structure of O has not changed and has good crystallinity; in addition, the deposited metal oxide is amorphous, so the diffraction peak corresponding to the oxide cannot be observed.

[0066] Example 2

[0067] Step 1, weigh 250 ml of vanadium oxyphosphate monohydrate, disperse it in 30 ml of deionized water, and ultrasonicate for 0.5 h to obtain solution A;

[0068] Step 2, weighing 15 mg of cobalt acetate tetrahydrate and 90 mg of anhydrous sodium iodide and adding them to solution A to obtain solution B;

[0069] Step 3, sonicate solution B for 1 h, and the solution gradually changes from wine red to black;

[0070] Step 4, pour the ultrasonicated solution B into the 50 ml reactor liner, then fix the liner in the outer reactor, put it into a forced air drying oven, react at 140°C for 11 hours, and wash the product alternately with water and alcohol twice;

[0071] Step 5, vacuum drying and collecting the product, grinding to obtain cobalt-doped HNaV 6 O 16 ·4H 2 O powder sample;

[0072] Step 6, 0.4 g of HNaV 6 O 16 ·4H 2 O particles were added to 2.0 ml of 1.0 mg / ml CTAB aqueous solution and stirred for 20 min to obtain solution C;

[0073] Step 7: Add solution C dropwise into the 8 ml Ti 3 C 2 The Tx suspension was placed in a beaker and stirred for 20 min to obtain solution D;

[0074] Step 8: vacuum filter the solution D, wash it twice with deionized water to remove CTAB, and then vacuum dry the collected product to obtain cobalt-doped Ti 3 C 2 Tx-coated HNaV 6 O 16 ·4H 2 O powder sample;

[0075] Step 9: Cobalt doping with Ti 3 C 2 Tx-coated HNaV 6 O 16 ·4H 2 O powder is placed in the ALD reaction chamber, evacuated and heated to 110°C;

[0076] Step 10, in a vacuum environment, inert gas carries TMA vapor and deposits it on the cobalt-doped Ti 3 C 2 Tx-coated HNaV 6 O 16 ·4H 2 O particle surface, duration 50s;

[0077] Step 11, the inert carrier gas at a specific flow rate will dope the cobalt with Ti 3 C 2 Tx-coated HNaV 6 O 16 ·4H 2The physically adsorbed TMA on the surface of O particles was blown off, leaving a layer of chemically adsorbed TMA, and the blowing time was 110 s;

[0078] Step 12: Water generates steam pressure by itself and cobalt doping synergistically with Ti 3 C 2 Tx-coated HNaV 6 O 16 ·4H 2 TMA adsorbed on the surface of O particles undergoes redox reaction;

[0079] Step 13, the inert carrier gas at a specific flow rate will dope the cobalt with Ti 3 C 2 Tx-coated HNaV 6 O 16 ·4H 2 The byproducts and excess water molecules on the surface of the O particles were blown off the surface, and the flow time was 110s; after standing still, the chamber was purged with inert gas to complete an ALD cycle. Multiple cycles were performed under the same deposition conditions to complete the specified thickness of Al 2 O 3 of deposition.

[0080] Example 3

[0081] Step 1, weigh 350 mg of vanadium oxyphosphate monohydrate, disperse it in 40 ml of deionized water, and ultrasonicate for 1.5 hours to obtain solution A;

[0082] Step 2, weighing 16 mg of cobalt acetate tetrahydrate and 95 mg of anhydrous sodium iodide, and adding them to solution A to obtain solution B;

[0083] Step 3, sonicate solution B for 3 h, and the solution gradually changes from wine red to black;

[0084] Step 4, pour the ultrasonicated solution B into the 50 ml reactor liner, then fix the liner in the outer reactor, put it into a blast drying oven, react at 160° C. for 13 h, and wash the product with 4 water and 4 alcohols alternately;

[0085] Step 5, vacuum drying and collecting the product, grinding to obtain cobalt-doped HNaV 6 O 16 ·4H 2 O powder sample;

[0086] Step 6, 0.6 g of HNaV 6 O 16 ·4H 2 O particles were added to 3.0 ml of 1.5 mg / ml CTAB aqueous solution and stirred for 40 min to obtain solution C;

[0087] Step 7: Add solution C dropwise into the 10 ml Ti 3 C 2 The Tx suspension was placed in a beaker and stirred for 40 min to obtain solution D;

[0088] Step 8: vacuum filter the solution D, wash it with deionized water 4 times to remove CTAB, and then vacuum dry the collected product to obtain cobalt-doped Ti 3 C 2 Tx-coated HNaV 6 O 16 ·4H 2 O powder sample;

[0089] Step 9: Cobalt doping with Ti 3 C 2 Tx-coated HNaV 6 O 16 ·4H 2 O powder is placed in the ALD reaction chamber, evacuated and heated to 130°C;

[0090] Step 10, in a vacuum environment, inert gas carries TMA vapor and deposits it on the cobalt-doped Ti 3 C 2 Tx-coated HNaV 6 O 16 ·4H 2 O particle surface, duration 70s;

[0091] Step 11, the inert carrier gas at a specific flow rate will dope the cobalt with Ti 3 C 2 Tx-coated HNaV 6 O 16 ·4H 2 The physically adsorbed TMA on the surface of O particles was blown off, leaving a layer of chemically adsorbed TMA, and the blowing time was 130 s;

[0092] Step 12: Water generates steam pressure by itself and cobalt doping synergistically with Ti 3 C 2 Tx-coated HNaV 6 O 16 ·4H 2 TMA adsorbed on the surface of O particles undergoes redox reaction;

[0093] Step 13, the inert carrier gas at a specific flow rate will dope the cobalt with Ti 3 C 2 Tx-coated HNaV 6 O 16 ·4H 2The byproducts and excess water molecules on the surface of the O particles were blown off the surface, and the flow time was 130s; after standing still, the chamber was purged with inert gas to complete an ALD cycle. Multiple cycles were performed under the same deposition conditions to complete the specified thickness of Al 2 O 3 of deposition.

Claims

1. A method for preparing a metal oxide positive electrode modified by atomic layer deposition technology, characterized in that: The specific steps include: Step 1, weighing vanadium oxyphosphate monohydrate, dispersing it in deionized water and ultrasonically treating it to obtain solution A; Step 2, weighing cobalt acetate tetrahydrate and anhydrous sodium iodide and adding them to solution A to obtain solution B; Step 3, subjecting solution B to ultrasonic treatment; Step 4, pour the ultrasonicated solution B into the inner lining of the reaction kettle, then fix the inner lining in the outer kettle, put it into a forced air drying oven for drying, and then wash it; Step 5: collect the product after vacuum drying and grind it to obtain cobalt-doped HNaV6O 16 4H2O powder sample; Step 6: HNaV6O 16 4H2O was added to the CTAB aqueous solution and stirred continuously to obtain solution C; Step 7, drop solution C into the beaker of Ti3C2Tx suspension and continue stirring to obtain solution D; Step 8: vacuum filter the solution D, wash and dry it to obtain the cobalt-doped Ti3C2Tx-coated HNaV6O 16 4H2O powder sample; Step 9, placing the powder obtained in step 8 into an ALD reaction chamber, evacuating the chamber and heating the chamber; Step 10, in a vacuum environment, inert gas carries TMA vapor and deposits it on the cobalt-doped Ti3C2Tx-coated HNaV6O 16 4H2O particle surface; Step 11, the inert carrier gas at a specific flow rate is used to transfer the cobalt-doped Ti3C2Tx-coated HNaV6O 16 ·4H2O The physically adsorbed TMA on the particle surface is blown off, leaving a layer of chemically adsorbed TMA; Step 12: Water generates its own vapor pressure by standing still and reacts with the cobalt-doped Ti3C2Tx-coated HNaV6O 16 ·4H2O The TMA adsorbed on the particle surface undergoes redox reaction; Step 13, the inert carrier gas at a specific flow rate is used to transfer the cobalt-doped Ti3C2Tx-coated HNaV6O 16 ·Blow away the byproducts and excess water molecules on the surface of 4H2O particles; after standing, purge the chamber with inert gas to complete an ALD cycle. Perform multiple cycles under the same deposition conditions to complete the deposition of Al2O3 of a specified thickness; The step 1 is specifically as follows: 250-350 mg of vanadium oxyphosphate monohydrate is dispersed in 30-40 ml of deionized water, and ultrasonically treated for 0.5 h to 1.5 h at a power of 80-120 W at room temperature; The step 2 is specifically as follows: weighing 15-16 mg of cobalt acetate tetrahydrate and 90-95 mg of anhydrous sodium iodide and adding them to solution A; In step 4, the drying temperature is 140-160° C., the reaction time is 11-13 hours, and the washing process is: washing with water 2-4 times and alcohol 2-4 times alternately; In step 5, the vacuum drying condition is 50-70° C., and the drying time is 11-13 hours. Before vacuum drying, the product is sealed with a plastic wrap, and then the plastic wrap is pierced.

2. The method for preparing a metal oxide positive electrode modified by atomic layer deposition technology according to claim 1, characterized in that: In step 3, ultrasonic treatment is performed for 1 h to 3 h at a power of 80 to 120 W at room temperature until the solution gradually changes from wine red to black.

3. The method for preparing a metal oxide positive electrode modified by atomic layer deposition technology according to claim 1, characterized in that: The specific step 6 is: 0.4-0.6 g of HNaV6O 16 4H2O particles were added to 2.0~3.0ml of 1.0~1.5mg / ml CTAB aqueous solution, and stirred continuously for 20~40min at a stirring speed of 400~600r / min to obtain solution C; The step 7 is specifically as follows: dripping solution C into a beaker with 8-10 ml of layered Ti3C2Tx suspension, stirring continuously for 20-40 min at a stirring speed of 400-600 r / min, to obtain solution D.

4. The method for preparing a metal oxide positive electrode modified by atomic layer deposition technology according to claim 1, characterized in that: The washing and drying process in step 8 is: washing with deionized water for 2 to 4 times to remove CTAB, and then vacuum drying to collect the product, the vacuum drying conditions are 50 to 70° C., and drying for 11 to 13 hours.

5. The method for preparing a metal oxide positive electrode modified by atomic layer deposition technology according to claim 1, characterized in that: In step 9, before the powder is placed in the ALD reaction chamber, the powder is vibrated and dispersed, and the temperature is raised to 110-130° C. under vacuum; In step 10, the inert gas flow rate is 40 ml / min and the duration is 50-70 s.

6. The method for preparing a metal oxide positive electrode modified by atomic layer deposition technology according to claim 1, characterized in that: In step 11, the inert gas flow rate is 80 ml / min, and the blow-off time is 110-130 s; In step 12, the water injection time is 60 seconds; In step 13, the inert gas flow rate is 80 ml / min and the duration is 110-130 s.

7. The metal oxide prepared by the method for preparing a metal oxide positive electrode modified by atomic layer deposition technology according to any one of claims 1 to 6, combined with Ti3C2Tx coating and synergistically doped HNaV6O 16 Application of 4H2O in lithium / sodium ion batteries.

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