Composite positive electrode material, preparation method thereof and sodium ion battery

Abstract

The application discloses a kind of composite positive electrode material and its preparation method and sodium ion battery, wherein the method includes the following steps: lithium fluoride is added in concentrated hydrochloric acid solution and completely dissolved, and slowly add MXene precursor and stir sufficiently, to obtain colloidal suspension solution;The colloidal suspension solution is washed by centrifugation with anhydrous ethanol, and the supernatant pH value is detected, then stepwise ultrasonic treatment and vacuum freeze drying are carried out, to obtain MXene nanosheet powder;MXene nanosheet powder is placed in silver nitrate aqueous solution, and soaked in dark environment, then irradiated with ultraviolet lamp, after irradiation, centrifugal washing separation and drying treatment, to obtain Ag / MXene nanocomposite material;Weigh copper source, nickel source, iron source and manganese source, and into sodium chloride solution, and add Ag / MXene nanocomposite material, continue to soak in dark environment, then irradiated with ultraviolet lamp, after irradiation, centrifugal washing separation and drying treatment, to obtain metal nanocomposite positive electrode material.The application aims to obtain positive electrode material that can improve the comprehensive performance of battery.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of sodium ion battery positive electrode materials, and particularly relates to a composite positive electrode material and a preparation method thereof and a sodium ion battery. BACKGROUND

[0002] At present, lithium ion batteries are widely applied to mobile electronic devices, computers, electric vehicles, communication and energy storage and the like, but due to the poor reserves and uneven distribution of lithium resources, it is difficult to meet the rapidly growing application demand, so that the large-scale development is seriously restricted. Sodium and lithium are in the same main group, have similar physical and chemical properties, and sodium is the sixth most abundant element in the world and is widely distributed. Further, the sodium ion battery is considered to be the next generation of energy storage system that can replace the lithium ion battery, and in the sodium ion battery, the positive electrode material is an important component and plays a key role in providing sodium ions and determining the energy density of the battery. Among them, the layered transition metal oxide is considered to be the most competitive and commercially potential and is expected to be the first to be industrialized sodium ion battery positive electrode material due to its rich variety, high discharge voltage, high energy density and easy synthesis.

[0003] In the sodium ion battery layered oxide, the sodium salt of the quaternary material copper-nickel-iron-manganese has the advantages of rich raw materials, low price, good cycle performance and moderate specific capacity, but there are still some defects, such as poor structural stability, poor conductivity, difficulty in controlling the morphology of the product, and the electrolyte will also erode the positive electrode material, eventually leading to rapid capacity decay of the positive electrode material, severe polarization, poor cycle stability and the like. It can be seen that the performance of the single-component sodium ion battery positive electrode material is limited by the characteristics of the material itself, thereby hindering its practical application. Therefore, surface modification is needed, including ion doping, conductive material compounding or noble metal deposition, and the existing patent with the patent number CN115548337A discloses a surface modified battery material, a preparation method thereof and a battery. The battery material is mixed and reacted with a salt solution (including inorganic salt and organic salt) heated to a high temperature, the surface structure of the battery material is changed, surface doping, defect manufacturing and / or functional group grafting are realized. Although the battery material using the salt solution quenching method has higher specific capacity, higher first cycle coulombic efficiency and capacity retention rate compared with the unmodified material, the charge and discharge rate growth is limited, so that the comprehensive performance of the prepared battery is not high. SUMMARY

[0004] The main purpose of the present application is to provide a composite positive electrode material and a preparation method thereof and a sodium ion battery, aiming at solving the technical problem of the low comprehensive performance of the existing sodium ion battery.

[0005] To achieve the above-mentioned purpose, the present application provides a preparation method of a composite positive electrode material, which comprises the following steps:

[0006] Step 1, a predetermined mass of lithium fluoride is added to a concentrated hydrochloric acid solution to dissolve completely, and a MXene precursor is slowly added and stirred for a predetermined time to obtain a colloidal suspension solution;

[0007] Step 2, the colloidal suspension solution is washed by centrifugation with anhydrous ethanol, and the pH value of the supernatant is detected until the pH value reaches 5-10, then stepwise ultrasonic treatment and vacuum freeze-drying are carried out to obtain MXene nanosheet powder;

[0008] Step 3, the MXene nanosheet powder is placed in an aqueous silver nitrate solution and soaked in the dark environment for 2-12h, so that Ag + is fully adsorbed on the MXene nanosheet, and then irradiated by ultraviolet lamp for a predetermined time, so that Ag + is generated in situ; 0 After irradiation, the Ag / MXene nanocomposite is obtained by centrifugal separation with anhydrous ethanol and vacuum freeze-drying treatment;

[0009] Step 4, weigh a predetermined mass of copper source, nickel source, iron source and manganese source, and immerse them in a sodium chloride solution, and add the Ag / MXene nanocomposite prepared in step 3, continuously soak in the dark environment for 2-12h, so that the sodium ion quaternary positive electrode material is generated in situ on the MXene nanosheet and the AgCl nanoparticles are successfully deposited, then irradiated by ultraviolet lamp for a predetermined time, so that the remaining Ag + is generated in situ to form Ag 0 , and after irradiation, the Na m Cu 1-x-y-z Ni x Fe y Mn z O2 / MXene metal nanocomposite positive electrode material is obtained by centrifugal separation with anhydrous ethanol and vacuum freeze-drying treatment, wherein 0.5≤m≤1.5, 0

[0010] Optionally, in step 1, the mass-volume ratio of lithium fluoride to concentrated hydrochloric acid solution is (1-5) g:(15-100) mL, and the mass fraction of concentrated hydrochloric acid solution is 34%.

[0011] Optionally, in step 2, the MXene nanosheet includes Ti3C2T x , Nb2CT x , Mo2CT x , V2CT x , Ti2CT x , Ti2NT x , V4C3T x , Nb4C3Tx Ti3CNT x Ta4C3T x and TiNbCT x at least one of them.

[0012] Optionally, in step 2, the time of the stepwise ultrasonic treatment is 10-120 min.

[0013] Optionally, in step 3, the concentration of the silver nitrate aqueous solution is 0.1 mol / L, and the mass-volume ratio of the MXene nanosheet powder to the silver nitrate aqueous solution is (10-500) mg:(10-50) mL.

[0014] Optionally, in step 4, the copper source includes at least one of copper sulfate, copper chloride, copper nitrate and copper acetate, the nickel source includes at least one of nickel sulfate, nickel chloride, nickel nitrate and nickel acetate, the iron source includes at least one of iron sulfate and / or ferrous sulfate, iron chloride and / or ferrous chloride, iron nitrate and / or ferrous nitrate, iron citrate and iron acetate, and the manganese source includes at least one of manganese sulfate, manganese chloride, manganese nitrate and manganese acetate.

[0015] Optionally, in step 4, the corresponding metal molar ratio of the copper source, the nickel source, the iron source and the manganese source is (0-1):(0-0.5):(0-0.5):(0-1).

[0016] Optionally, the time of the ultraviolet lamp irradiation in step 3 and step 4 is 60 min, respectively.

[0017] In addition, in order to achieve the above-mentioned purpose, the application further provides a composite positive electrode material, which is prepared according to the preparation method of the sodium ion positive electrode material of any one of the above-mentioned.

[0018] In addition, in order to achieve the above-mentioned purpose, a sodium ion battery includes a positive electrode sheet, which is prepared by adding the above-mentioned composite positive electrode material, a conductive agent and a binder PVDF into an NMP solution in a mass ratio of 8:1:1 and fully stirring and mixing, then uniformly coating on an aluminum foil, and finally baking in a vacuum drying oven at 70-100 DEG C.

[0019] Beneficial effects:

[0020] (1) The acid etching method assisted stepwise ultrasonic treatment is used to prepare MXene nanosheet layers, which have an ultrathin layered structure and a unique large specific surface area, thereby improving the dispersity and uniformity of the composite positive electrode material, and further making Na m Cu 1-x-y-z Ni x Fe y Mn zO2 cathode material is in-situ grown on the surface of MXene nanosheet, and the noble metal Ag nanoparticles and AgCl introduced by the immersion-photoreduction method increase the conductivity and active sites of the composite material, and the optimized interlayer spacing and increased active sites make the composite material have a faster charge and discharge rate. And the stepwise ultrasonic treatment improves the interlayer spacing of the two-dimensional MXene nanosheet, avoids the problem of interlayer collapse, and improves the interlayer energy storage space.

[0021] (2) Based on the excellent mechanical properties and high conductivity of the prepared two-dimensional material MXene nanosheet, not only can it be used as a carrier to support the sodium ion battery cathode material, but also can improve the conductivity of the composite material, promote the transmission of Na + , and the two-dimensional material MXene nanosheet has high chemical stability and thermal stability, can form a protective barrier to avoid the contact between the electrolyte and the cathode material. Reduce the side reaction between the cathode material and the electrolyte. Thus effectively inhibiting the rapid capacity decay problem of the battery during the cycle process.

[0022] (3) The whole preparation process is simple and controllable, easy to operate, does not need special instruments and experimental conditions, low cost, low energy consumption, green and feasible.

[0023] (4) The loaded noble metal Ag nanoparticles and their derivatives AgCl and MXene nanosheet are mutually synergistic and complementary, which improves the overall structural stability of the composite material, and the discharge capacity and cycle stability of the composite material are obviously improved, and the electrochemical performance is excellent. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 is the flowchart of the preparation method of the sodium ion battery composite cathode material in the embodiment of the present application.

[0025] Figure 2 is the preparation flowchart of the MXene nanosheet powder in Figure 1 ;

[0026] Figure 3 is the scanning electron microscope image of the monolayer Ti3C2T X nanosheet obtained after etching and ultrasonic treatment of aluminum atoms in the precursor Ti3AlC2 in embodiment 1 of the present application.

[0027] Figure 4 is the atomic force microscope image of the monolayer Ti3C2T X nanosheet obtained after etching and ultrasonic treatment of aluminum atoms in the precursor Ti3AlC2 in embodiment 1 of the present application.

[0028] Figure 5 is Na m Cu in embodiment 6 of the present application.1-x-y-z Ni x Fe y Mn z O2 / Ag@AgCl / Ti3C2T X Scanning electron microscope image of the composite positive electrode material of the sodium ion battery at 5000 times.

[0029] Figure 6 Na for the embodiment 7 in the application m Cu 1-x-y-z Ni x Fe y Mn z O2 / Ag@AgCl / Ti3C2T X Scanning electron microscope image of the composite positive electrode material of the sodium ion battery at 10000 times.

[0030] Figure 7 Na for the embodiment 7 in the application m Cu 1-x-y-z Ni x Fe y Mn z O2 / Ag@AgCl / Ti3C2T X X-ray diffraction pattern of the composite positive electrode material of the sodium ion battery.

[0031] The implementation, functional features and advantages of the application will be further described with reference to the embodiments and the accompanying drawings. DETAILED DESCRIPTION

[0032] It should be understood that the specific embodiments described herein are merely intended to explain the application and are not intended to limit the application.

[0033] Referring to Figures 1-2 The application provides a flowchart of a preparation method of a composite positive electrode material, wherein the method comprises the following steps:

[0034] Step 1: a lithium fluoride with a preset mass is added into a concentrated hydrochloric acid solution and completely dissolved, and a MXene precursor is slowly added and fully stirred for a preset time, so as to perform etching reaction on the MXene precursor by taking the hydrochloric acid and the lithium fluoride as etching agents, and obtain a colloidal suspension solution. The mass-volume ratio of the lithium fluoride to the concentrated hydrochloric acid solution is (1-5) g:(15-100) mL, preferably 1 g:15 mL, the mass fraction of the concentrated hydrochloric acid solution is 34%, and the concentration is 9 mol / L. Preferably, the MXene precursor comprises at least one of Ti3AlC2, Nb2AlC, Mo2AlC, V2AlC, Ti2AlC, Ti2AlN, V4AlC3, Nb4AlC3, Ti3AlCN, Ta4AlC3 and TiNbAlC, and the MXene nanosheet after the etching reaction comprises Ti3C2Tx 、Nb2CT x 、Mo2CT x 、V2CT x 、Ti2CT x 、Ti2NT x 、V4C3T x 、Nb4C3T x 、Ti3CNT x 、Ta4C3T x and TiNbCT x At least one of them shows that MXene nanosheets are obtained by etching reaction, acid leaching to remove aluminum, and then centrifugal washing and ultrasonic peeling.

[0035] In step 2, the colloidal suspension solution is centrifuged and washed with anhydrous ethanol, and the pH value of the supernatant is detected until the pH value reaches 5 to 10, and then step-by-step ultrasonic treatment and vacuum freeze-drying are performed to obtain MXene nanosheet powder. The anhydrous ethanol centrifugal washing is performed multiple times, and the pH value of the supernatant after washing is detected in real time. Preferably, the pH value can be, but is not limited to, 5, 6, 7, 8, 9, or 10. The time for the step-by-step ultrasonic treatment is 10 to 120 minutes. The initial purpose of the ultrasonic treatment is to improve the interlayer spacing of the MXene material and avoid interlayer collapse. The thickness of the MXene nanosheet finally obtained is nanometer-level, specifically 1-2 nm, and is a single-layer sheet structure with a high yield.

[0036] Step 3: Place the MXene nanosheet powder in a silver nitrate aqueous solution and soak it in a dark environment for 2 to 12 hours to allow the Ag + Ag is fully adsorbed on the MXene nanosheets and then irradiated with UV light for a preset time to allow the Ag + In situ generation of Ag 0 After irradiation, the Ag / MXene nanocomposite material is separated by centrifugal washing with anhydrous ethanol and subjected to vacuum freeze-drying treatment. The Ag / MXene nanocomposite material is deposited on the MXene nanosheets to increase the conductivity and active sites of the composite material. That is, in this step, metal Ag nanoparticles are in situ deposited on the pretreated MXene nanosheets by the impregnation-photoreduction method. The noble metal Ag nanoparticles and AgCl introduced by the impregnation-photoreduction method increase the conductivity and active sites of the composite material. The optimized interlayer spacing and increased active sites make the composite material have a faster charge and discharge rate. The UV irradiation time is 60 min, the concentration of the silver nitrate aqueous solution is 0.1 mol / L, and the mass volume ratio of the MXene nanosheet powder to the silver nitrate aqueous solution is (10-500) mg: (10-50) mL, preferably 1 mg: 1 mL.

[0037] Step 4: Weigh the preset mass of copper source, nickel source, iron source and manganese source, immerse them in sodium chloride solution, and add the Ag / MXene nanocomposite prepared in step 3, and continue to soak in a dark environment for 2 to 12 hours to in situ generate sodium ion quaternary positive electrode material on the MXene nanosheets and successfully deposit AgCl nanoparticles, and then irradiate with ultraviolet light for a preset time to make the remaining Ag + In situ generation of Ag 0 After irradiation, Na m Cu 1-x-y-z Ni x Fe y Mn z O2 / MXene metal nanocomposite cathode material, wherein 0.5≤m≤1.5, 0 <x<0.5,0<y<0.5,0<z<1,0<1-x-y-z<1,且在金属纳米复合正极材料通式中的铜、镍、铁及锰原子数总和为1。以及铜源、镍源、铁源及锰源均为对应的金属盐,优选地,所述铜源包括硫酸铜、氯化铜、硝酸铜和乙酸铜中的至少一种,所述镍源包括硫酸镍、氯化镍、硝酸镍和乙酸镍中的至少一种,所述铁源包括硫酸铁和 / 或硫酸亚铁、氯化铁和 / 或氯化亚铁、硝酸铁和 / 或硝酸亚铁、柠檬酸铁和乙酸铁中的至少一种,所述锰源包括硫酸锰、氯化锰、硝酸锰和乙酸锰中的至少一种。该步骤中的贵金属Ag纳米粒子及其衍生物AgCl以及MXene纳米片之间相互协同,优势互补,提高了复合材料整体的结构稳定性,使复合材料的放电克容量和循环稳定性得到了明显提高,电化学性能优异。

[0038] Furthermore, in step 4, the corresponding metal molar ratios of the copper source, nickel source, iron source and manganese source are (0-1):(0-0.5):(0-0.5):(0-1).

[0039] Furthermore, in step 4, the UV lamp irradiation time is 60 minutes.

[0040] Furthermore, the soaking time in steps 3 and 4 can be, but is not limited to, 2 h, 3 h, 4 h, 5 h, 6 h, 7 h, 8 h, 9 h, 10 h, 11 h, or 12 h.

[0041] Further, the above-mentioned composite cathode material, conductive agent and binder PVDF are added into NMP solution in a mass ratio of 8:1:1, and then mixed by fully stirring, and then uniformly coated on an aluminum foil, and finally baked in a vacuum drying oven at 70-100 DEG C to obtain a cathode sheet, and the cathode sheet is paired with a metal sodium negative electrode to assemble a CR2032 type button cell in an inert atmosphere glove box.

[0042] The present application is based on a single Na m Cu 1-x-y-z Ni x Fe y Mn z O2 quaternary cathode material has poor rate performance, stability and conductivity, and is prone to side reactions with electrolyte, resulting in reduced capacity and poor cycle performance, and the surface of the quaternary cathode material is modified by MXene nanosheet and noble metal Ag nanoparticle, and the MXene nanosheet has good chemical stability, thermal stability and mechanical properties, high conductivity and large specific surface area, and can also be used as a good carrier to support the sodium ion battery cathode material, improve the conductivity of the cathode material and promote the transmission of Na + , and can also form a protective barrier for the cathode material to reduce the continuous erosion of the electrolyte on the cathode material, inhibit the capacity decay problem of the battery during the cycle process, and the noble metal Ag nanoparticle and its derivative AgCl can increase the conductivity and active sites of the cathode material, thereby making the quaternary / MXene metal nanocomposite have faster charge and discharge rate and excellent electrochemical performance.

[0043] Further, in order to better illustrate the preparation process of the composite cathode material in the present application, the following specific examples are described in detail.

[0044] Example 1

[0045] The present application provides a novel quaternary Na m Cu 1-x-y-z Ni x Fe y Mn z O2 / Ag@AgCl / Ti3C2T X The preparation method of the metal nanocomposite cathode material and the sodium ion battery comprises the following steps:

[0046] (1) Prepare a concentrated hydrochloric acid solution of a certain concentration, add lithium fluoride to the above hydrochloric acid solution and stir for 10-20 minutes until the lithium fluoride is completely dissolved, then slowly add Ti3AlC2 to the solution to prevent violent reaction, and continue stirring for a certain time after the addition is completed. After the etching reaction is completed, the obtained colloidal suspension solution is centrifuged and washed several times with anhydrous ethanol, and the pH of the supernatant is tested until the pH value of the supernatant reaches 6. Then ultrasonically treat it for 60 minutes to make it uniformly dispersed, and Ti3C2T X Nanosheet ethanol solution, and finally Ti3C2T X Ti3C2T nanosheets can be obtained by vacuum freeze drying of ethanol solution. X Nanosheet powder, for observing Ti3C2T X- The microscopic morphology of MXene nanosheets was investigated by scanning electron microscopy and atomic force microscopy after dilution and air drying of the colloidal solution. Figures 3-4 The scanning electron microscope and atomic force microscope shown in the figure show that Ti3C2T X- MXene shows a single-layer lamellar structure, with each layer separated from each other and dispersed relatively evenly.

[0047] (2) T i3C2T X After weighing the nanosheet powder, place it in a beaker containing silver nitrate aqueous solution and seal it with laboratory sealing film and let it stand to promote the adsorption of silver ions. This process is carried out in a dark environment. Soak for 2 hours to allow Ag + Fully adsorbed on Ti3C2T X The solution in the beaker was then irradiated with a laboratory UV lamp for 60 minutes to reduce the Ag + In situ generation of Ag 0 , Ag 0 Successfully in situ deposited on Ti3C2T X On nanosheets.

[0048] (3) According to the stoichiometric ratio of each element in the quaternary material, copper acetate, nickel acetate, ferrous chloride and manganese acetate were weighed and immersed in sodium chloride solution for in-situ oxidation. X Nanocomposite materials were added and soaked for 3 hours to form Ti3C2T X The sodium ion quaternary positive electrode material was generated in situ on the nanosheet and AgCl nanoparticles were successfully deposited. The nanosheet was sealed with a laboratory sealing film and left to stand directly. This process also needed to be operated in a dark environment. m Cu 1-x-y-z Ni x Fe y Mn z O2 on Ti3C2TX The nanosheet is fully reacted, and the solution after soaking is exposed to a UV lamp for irradiation for 60 minutes to reduce part of the residual Ag + to elemental Ag 0 . Then, the Na m Cu 1-x-y-z Ni x Fe y Mn z O2 / Ag@AgCl / Ti3C2T X metal nanocomposite positive electrode material is obtained by centrifugal washing and separation with anhydrous ethanol and vacuum freeze-drying.

[0049] (4) The above-synthesized Na m Cu 1-x-y-z Ni x Fe y Mn z O2 / Ag@AgC l / Ti3C2T X metal nanocomposite positive electrode material is added to an NMP solution in a mass ratio of 8:1:1 with a conductive agent and a binder PVDF, fully stirred and mixed to obtain a uniform slurry, and then the slurry is uniformly coated on an aluminum foil and placed in a vacuum drying oven for baking at 70°C to obtain a positive electrode sheet.

[0050] (5) The positive electrode sheet in step (4) is paired with a metal sodium negative electrode to assemble a CR2032 type button cell in an inert atmosphere-filled glove box, and the electrochemical performance of the composite positive electrode material is tested.

[0051] Example 2

[0052] The present embodiment provides a novel quaternary Na m Cu 1-x-y-z Ni x Fe y Mn z O2 / Ag@AgC l / Nb2CT X metal nanocomposite positive electrode material and a sodium ion battery, comprising the following steps:

[0053] (1) A certain concentration of hydrochloric acid solution is configured, lithium fluoride is added to the above hydrochloric acid solution and stirred for 10-20 minutes until the lithium fluoride is completely dissolved, and then Nb2Al C is slowly added to the solution to prevent violent reaction, and stirring is continued for a certain period of time after the addition is completed. After the etching reaction is completed, the obtained colloidal suspension solution is centrifugally washed with anhydrous ethanol for multiple times, and the pH of the supernatant is tested until the pH value of the supernatant reaches 5. Ultrasonic treatment is performed for 60 minutes to uniformly disperse, and the Nb2CT X nanosheet ethanol solution is obtained. Finally, the Nb2CT XNb2CT can be obtained by vacuum freeze drying of nanoethanol solution X Nanosheet powder.

[0054] (2) Nb2CT X After weighing the nanosheet powder, place it in a beaker containing silver nitrate aqueous solution and seal it with laboratory sealing film and let it stand to promote the adsorption of silver ions. This process was carried out in a dark environment. Soak for 4 hours to allow Ag + Fully adsorbed on Nb2CT X The solution in the beaker was then irradiated with a laboratory UV lamp for 60 minutes to reduce the Ag + In situ generation of Ag 0 , Ag 0 Successfully in situ deposited on Nb2CT X On nanosheets;

[0055] (3) According to the stoichiometric ratio of each element in the quaternary material, copper acetate, nickel acetate, ferrous chloride and manganese acetate were weighed and immersed in sodium chloride solution for in-situ oxidation. X The nanocomposite materials were added and immersed for 5 hours to form Nb2CT X The sodium ion quaternary positive electrode material was generated in situ on the nanosheet and AgCl nanoparticles were successfully deposited. The nanosheet was sealed with a laboratory sealing film and left to stand directly. This process also needed to be operated in a dark environment. m Cu 1-x-y-z Ni x Fe y Mn z O2 in Nb2CT X The nanosheets were fully reacted and the solution was exposed to ultraviolet light for 60 minutes to remove some of the residual Ag. + Reduced to elemental Ag 0 Then centrifuge and wash with anhydrous ethanol to separate. Finally, vacuum freeze-dry to obtain Na m Cu 1-x-y-z Ni x Fe y Mn z O2 / Ag@AgCl / Nb2CT X Metal nanocomposite cathode materials.

[0056] (4) The Na m Cu 1-x-y-z Ni x Fe y Mn z O2 / Ag@AgCl / Nb2CT XThe metal nanocomposite cathode material, conductive agent and binder PVDF are added into NMP solution in a mass ratio of 8:1:1, stirred and mixed to obtain a uniform slurry, then the slurry is uniformly coated on an aluminum foil, and the positive electrode sheet is obtained by baking in a vacuum drying oven at 70°C.

[0057] (5) The positive electrode sheet in step (4) is paired with a metal sodium negative electrode to assemble a CR2032 type button cell in an inert atmosphere filled glove box, and the electrochemical performance of the composite cathode material is tested.

[0058] Example 3

[0059] The present embodiment provides a novel quaternary Na m Cu 1-x-y-z Ni x Fe y Mn z O2 / Ag@AgCl / Ta4C3T X The preparation method of the metal nanocomposite cathode material and the sodium ion battery comprises the following steps:

[0060] (1) A certain concentration of hydrochloric acid solution is prepared, lithium fluoride is added to the above hydrochloric acid solution and stirred for 10-20 minutes until the lithium fluoride is completely dissolved, then Ta4Al C3 is slowly added to the solution to prevent violent reaction, and stirring is continued for a certain period of time after the addition is completed. After the etching reaction is completed, the obtained colloidal suspension solution is washed by centrifugation with anhydrous ethanol for multiple times, and the pH of the supernatant is tested until the pH value of the supernatant reaches 7. Ultrasonic treatment for 60 minutes makes it uniformly dispersed, and Ta4C3T X nanosheet ethanol solution is obtained. Finally, the Ta4C3T X nanosheet ethanol solution is vacuum freeze-dried to obtain Ta4C3T X nanosheet powder.

[0061] (2) The Ta4C3T X nanosheet powder is weighed and placed in a beaker containing an aqueous silver nitrate solution, sealed with laboratory sealing film and directly placed to promote the adsorption of silver ions. This process is carried out in a dark environment. Soak for 6 hours to allow Ag + to be fully adsorbed on the Ta4C3T X nanosheet, then irradiate the solution in the beaker with a laboratory ultraviolet lamp for 60 minutes to reduce Ag + in situ generated Ag 0 , Ag 0 is successfully deposited in situ on the Ta4C3T X nanosheet;

[0062] (3) According to the stoichiometric ratio of each element in the quaternary material, copper acetate, nickel acetate, ferrous chloride and manganese acetate are weighed and immersed in a sodium chloride solution for in-situ oxidation. Then, the synthesized Ag / Ta4C3T X nanocomposite is added and soaked for 7h to generate a quaternary sodium ion positive electrode material in-situ on the Ta4C3T X nanosheet and successfully deposit AgCl nanoparticles. The process is also operated in a dark environment. The AgCl nanoparticles and quaternary Na m Cu 1-x-y-z Ni x Fe y Mn z O2 on the Ta4C3T X nanosheet are fully reacted. The solution after soaking is exposed to ultraviolet light for 60 minutes to reduce part of the residual Ag + to elemental Ag 0 . Then, anhydrous ethanol is used for centrifugal washing and separation. Finally, vacuum freeze-drying is used to obtain Na m Cu 1-x-y-z Ni x Fe y Mn z O2 / Ag@AgCl / Ta4C3T X metallic nanocomposite positive electrode material.

[0063] (4) The above-synthesized Na m Cu 1-x-y-z Ni x Fe y Mn z O2 / Ag@AgC l / Ta4C3T X metallic nanocomposite positive electrode material is added to an NMP solution according to a mass ratio of 8:1:1 with a conductive agent and a binder PVDF, and is fully stirred and mixed to obtain a uniform slurry. Then, the slurry is uniformly coated on an aluminum foil, and is placed in a vacuum drying oven for baking at 80°C to obtain a positive electrode sheet.

[0064] (5) The positive electrode sheet in step (4) is paired with a metallic sodium negative electrode to assemble a CR2032 type button cell in an inert atmosphere glove box, and the electrochemical performance of the composite positive electrode material is tested.

[0065] Example 4

[0066] This example provides a new type of quaternary Na m Cu 1-x-y-z Ni x Fe y Mn z O2 / Ag@AgC l / V4C3TX A preparation method of a metal nanocomposite positive electrode material and a sodium ion battery, comprising the following steps:

[0067] (1) A certain concentration of concentrated hydrochloric acid solution is configured, lithium fluoride is added to the above hydrochloric acid solution and stirred for 10-20 minutes until the lithium fluoride is completely dissolved, then V4AlC3 is slowly added to the solution to prevent violent reaction, and stirring is continued for a certain period of time after the addition is completed. After the etching reaction is completed, the obtained colloidal suspension solution is washed by centrifugation with anhydrous ethanol for multiple times, and the pH of the supernatant is tested until the pH value of the supernatant reaches 8. Ultrasonic treatment for 60 minutes makes it uniformly dispersed, and V4C3T X nanosheet ethanol solution is obtained. X X nanosheet powder.

[0068] (2) The V4C3T X nanosheet powder is weighed and placed in a beaker containing an aqueous silver nitrate solution, sealed with a laboratory sealing film, and directly placed to promote the adsorption of silver ions. This process is carried out in a dark environment. After 8 hours of immersion, Ag + is fully adsorbed on the V4C3T X nanosheet, and then the solution in the beaker is irradiated with a laboratory ultraviolet lamp for 60 minutes to reduce Ag + generated in situ to Ag 0 , which is successfully deposited in situ on the V4C3T 0 nanosheet. X

[0069] (3) According to the stoichiometric ratio of each element in the quaternary material, copper acetate, nickel acetate, ferrous chloride and manganese acetate are weighed and immersed in a sodium chloride solution for in-situ oxidation. The synthesized Ag / V4C3T X nanocomposite is added and soaked together for 9 hours to generate sodium ion quaternary positive electrode material in situ on the V4C3T X nanosheet and successfully deposit AgCl nanoparticles. The beaker is sealed with a laboratory sealing film and directly placed, and this process also needs to be operated in a dark environment. The AgCl nanoparticles and quaternary Na m Cu 1-x-y-z Ni x Fe y Mn z O2 on the V4C3T X nanosheet fully react, and the solution after soaking is exposed to ultraviolet light for 60 minutes to reduce part of the residual Ag + to elemental Ag 0 ​​Then the isolated product is washed by centrifugation with anhydrous ethanol. Finally, vacuum freeze-drying is performed to obtain Na m Cu 1-x-y-z Ni x Fe y Mn z O2 / Ag@AgCl / V4C3T X Metal nanocomposite positive electrode material.

[0070] (4) The synthesized Na m Cu 1-x-y-z Ni x Fe y Mn z O2 / Ag@AgCl / V4C3T X Metal nanocomposite positive electrode material and conductive agent, binder PVDF are added to NMP solution in a mass ratio of 8:1:1, and stirred to obtain a uniform slurry. Then the slurry is uniformly coated on an aluminum foil, and placed in a vacuum drying oven at 80°C to obtain a positive electrode sheet.

[0071] (5) The positive electrode sheet in step (4) is paired with a metal sodium negative electrode to assemble a CR2032 type button cell in an inert atmosphere glove box, and the electrochemical performance of the composite positive electrode material is tested.

[0072] Example 5

[0073] This embodiment provides a novel quaternary Na m Cu 1-x-y-z Ni x Fe y Mn z O2 / Ag@AgCl / Ti3C2T X Preparation method of metal nanocomposite positive electrode material and sodium ion battery, comprising the following steps:

[0074] (1) A certain concentration of hydrochloric acid solution is prepared, lithium fluoride is added to the above hydrochloric acid solution and stirred for 10-20 minutes until the lithium fluoride is completely dissolved, then Ti3AlC2 is slowly added to the solution to prevent violent reaction, and stirring is continued for a certain period of time after the addition is completed. After the etching reaction is completed, the obtained colloidal suspension solution is washed by centrifugation with anhydrous ethanol for multiple times, and the pH of the supernatant is tested until the pH value of the supernatant reaches 9. Ultrasonic treatment is performed for 10 minutes to make it uniformly dispersed, and Ti3C2T X monolayer nanosheet ethanol solution is obtained, and finally Ti3C2T X nanosheet ethanol solution is vacuum freeze-dried to obtain Ti3C2T X nanosheet powder.

[0075] (2) Ti3C2TX The nanosheet powder was weighed and placed in a beaker containing an aqueous silver nitrate solution, sealed with a laboratory sealing film and left to stand directly to promote the adsorption of silver ions. This process was carried out in a dark environment throughout. The immersion was carried out for 10 h to allow the Ag + to be fully adsorbed on the Ti3C2T X nanosheets, and then the solution in the beaker was irradiated with a laboratory ultraviolet lamp for 60 minutes to reduce Ag + generated in situ on the Ti3C2T 0 nanosheets; 0 Ag X was successfully deposited in situ on the Ti3C2T

[0076] (3) According to the stoichiometric ratio of each element in the quaternary material, copper acetate, nickel acetate, ferrous chloride and manganese acetate were weighed and immersed in a sodium chloride solution for in-situ oxidation. The synthesized Ag / Ti3C2T X nanocomposite was added and soaked together for 11 h to generate a quaternary sodium ion positive electrode material in situ on the Ti3C2T X nanosheets and successfully deposit AgCl nanoparticles. The beaker was sealed with a laboratory sealing film and left to stand directly. This process also needed to be operated in a dark environment throughout. The AgCl nanoparticles and quaternary Na m Cu 1-x-y-z Ni x Fe y Mn z O2on the Ti3C2T X nanosheets were fully reacted, and the solution after soaking was exposed to ultraviolet light for 60 minutes to reduce part of the residual Ag + to elemental Ag 0 . Then it was washed and separated by centrifugation with anhydrous ethanol. Finally, vacuum freeze-drying was used to obtain Na m Cu 1-x-y-z Ni x Fe y Mn z O2Ag@AgCl / Ti3C2T X metal nanocomposite positive electrode material.

[0077] (4) The above-synthesized Na m Cu 1-x-y-z Ni x Fe y Mn z O2 / Ag@AgC l / Ti3C2T XThe metal nanocomposite cathode material, conductive agent and binder PVDF are added into NMP solution in a mass ratio of 8:1:1, stirred and mixed to obtain a uniform slurry, then the slurry is uniformly coated on an aluminum foil, and the positive electrode sheet is obtained by baking in a vacuum drying oven at 90°C.

[0078] (5) The positive electrode sheet in step (4) is paired with a metal sodium negative electrode to assemble a CR2032 type button cell in an inert atmosphere filled glove box, and the electrochemical performance of the composite cathode material is tested.

[0079] Example 6

[0080] The present embodiment provides a new type of quaternary Na m Cu 1-x-y-z Ni x Fe y Mn z O2 / Ag@AgCl / Ti3C2T X The preparation method of the metal nanocomposite cathode material and the sodium ion battery comprises the following steps:

[0081] (1) A certain concentration of hydrochloric acid solution is configured, lithium fluoride is added to the above hydrochloric acid solution and stirred for 10-20 minutes until the lithium fluoride is completely dissolved, then Ti3AlC2 is slowly added to the solution to prevent violent reaction, and stirring is continued for a certain period of time after the addition is completed. After the etching reaction is completed, the obtained colloidal suspension solution is washed by centrifugation with anhydrous ethanol for multiple times, and the pH of the supernatant is tested until the pH value of the supernatant reaches 10. Ultrasonic treatment for 120 minutes makes it uniformly dispersed, and Ti3C2T X single-layer nanosheet ethanol solution, and finally the MXene nanosheet ethanol solution is vacuum freeze-dried to obtain Ti3C2T X single-layer nanosheet powder.

[0082] (2) The Ti3C2T X Nanosheet powder is weighed and placed in a beaker containing silver nitrate aqueous solution, sealed with laboratory sealing film and directly placed to promote the adsorption of silver ions. This process is carried out in a dark environment. Soak for 12 hours to make Ag + fully adsorbed on the Ti3C2T X nanosheet, then the solution in the beaker is irradiated with a laboratory ultraviolet lamp for 60 minutes to reduce Ag + in situ generated Ag 0 , Ag 0 is successfully deposited in situ on the Ti3C2T X nanosheet;

[0083] (3) According to the stoichiometric ratio of each element in the quaternary material, copper acetate, nickel acetate, ferrous chloride and manganese acetate are weighed and immersed in a sodium chloride solution for in-situ oxidation. Then, the synthesized Ag / Ti3C2T X nanocomposite is added and soaked for 8 hours to generate a quaternary positive electrode material with sodium ions in-situ on the Ti3C2T X nanosheet and successfully deposit AgCl nanoparticles. The process is also operated in a dark environment. The AgCl nanoparticles and the quaternary Na m Cu 1-x-y-z Ni x Fe y Mn z O2 / Ag@AgCl / Ti3C2T X nanocomposite is exposed to a UV lamp for 60 minutes to reduce part of the residual Ag + to elemental Ag 0 . Then, the sample is centrifuged and washed with anhydrous ethanol. Finally, vacuum freeze-drying is performed to obtain Na m Cu 1-x-y-z Ni x Fe y Mn z O2 / Ag@AgCl / Ti3C2T X metallic nanocomposite positive electrode material. The prepared positive electrode material is tested by scanning electron microscopy at 5000 times, and the results are shown in Figure 5 FIG. 1. As can be seen from the figure, the sample as a whole presents a single crystal structure of a sodium battery quaternary positive electrode material, the particle size is below 5 microns, and the sample is distributed in layers, with a clean surface and fewer residual alkali particles.

[0084] (4) The above-synthesized Na m Cu 1-x-y-z Ni x Fe y Mn z O2 / Ag@AgCl / Ti3C2T X metallic nanocomposite positive electrode material is added to an NMP solution in a mass ratio of 8:1:1 with a conductive agent and a binder PVDF, and is fully stirred and mixed to obtain a uniform slurry. Then, the slurry is uniformly coated on an aluminum foil and is placed in a vacuum drying oven for baking at 90°C to obtain a positive electrode sheet.

[0085] (5) The positive electrode sheet in step (4) is paired with a metal sodium negative electrode to assemble a CR2032 type button cell in an inert atmosphere glove box to test the electrochemical performance of the composite positive electrode material.

[0086] Example 7

[0087] The embodiment provides a novel quaternary Na m Cu 1-x-y-z Ni x Fe y Mn z O2 / Ag@AgCl / Ti3C2T X The application discloses a preparation method of a metal nanocomposite positive electrode material and a sodium ion battery.

[0088] (1) A certain concentration of hydrochloric acid solution is configured, lithium fluoride is added into the hydrochloric acid solution and stirred for 10-20 minutes until the lithium fluoride is completely dissolved, then Ti3AlC2 is slowly added into the solution to prevent violent reaction, and stirring is continued for a certain time after the addition is completed. After the etching reaction is completed, the obtained colloidal suspension solution is centrifugally washed with anhydrous ethanol for multiple times, and the pH of supernatant is tested until the pH value of the supernatant reaches 6. The Ti3C2T X monolayer nanosheet ethanol solution is obtained. X monolayer nanosheet powder.

[0089] (2) The Ti3C2T X nanosheet powder is weighed and then immersed into a beaker containing an aqueous silver nitrate solution, and a laboratory sealing film is used to seal the beaker to promote adsorption of silver ions. The whole process is implemented in a dark environment. The immersion is performed for 8 hours to enable the Ag + to be fully adsorbed on the Ti3C2T X nanosheet, and then a laboratory ultraviolet lamp is used to irradiate the solution in the beaker for 60 minutes to reduce Ag + in situ to generate Ag 0 , and the Ag 0 is successfully deposited in situ on the Ti3C2T X nanosheet.

[0090] (3) According to the stoichiometric ratio of each element in the quaternary material, copper acetate, nickel acetate, ferrous chloride and manganese acetate are weighed and immersed into a sodium chloride solution for in-situ oxidation, and then the synthesized Ag / Ti3C2T X nanocomposite is added and immersed for 6 hours to generate a quaternary sodium ion positive electrode material in situ on the Ti3C2T X nanosheet and successfully deposit AgCl nanoparticles, and a laboratory sealing film is used to seal the beaker to directly stand, and the whole process needs to be implemented in a dark environment. The AgCl nanoparticles and the quaternary Na m Cu 1-x-y-z Ni x Fe y Mn z O2 on the Ti3C2TX The nanosheets are fully reacted, and the solution after soaking is exposed to a UV lamp for irradiation for 60 minutes to reduce part of the residual Ag + to elementary Ag 0 Then, the product is separated by centrifugal washing with anhydrous ethanol. Finally, vacuum freeze-drying is performed to obtain Na m Cu 1-x-y-z Ni x Fe y Mn z O2 / Ag@AgCl / Ti3C2T X metallic nanocomposite positive electrode material, and the prepared positive electrode material is subjected to scanning electron microscope test under 10000 times, and the results are shown in FIG. Figure 6 As can be seen from the figure, the sample as a whole still presents a single crystal morphology of sodium electric quaternary positive electrode material, the particle size is 1-5 microns, and the sample is in a layered distribution, the surface is clean, and the morphology is good. Further X-ray diffraction determination is performed, and the spectrum shown in FIG. Figure 7 is obtained. Analysis and comparison show that the diffraction peaks of the obtained sample in the range of 10°-80° are well matched with the PDF standard card of the sodium electric quaternary positive electrode material, and no obvious impurity peak appears. Therefore, it can be seen that the target product is successfully synthesized.

[0091] (4) The prepared Na m Cu 1-x-y-z Ni x Fe y Mn z O2 / Ag@AgC l / Ti3C2T X metallic nanocomposite positive electrode material is added to an NMP solution in a mass ratio of 8:1:1 with a conductive agent and a binder PVDF, and is fully stirred and mixed to obtain a uniform slurry. Then, the slurry is uniformly coated on an aluminum foil, and is placed in a vacuum drying oven for baking at 100°C to obtain a positive electrode sheet.

[0092] (5) The positive electrode sheet in step (4) is paired with a metal sodium negative electrode to assemble a CR2032 type button cell in an inert atmosphere glove box, and the electrochemical performance of the composite positive electrode material is tested.

[0093] Example 8

[0094] The present embodiment provides a novel quaternary Na m Cu 1-x-y-z Ni x Fe y Mn z O2 / Ag@AgCl / Ti3C2T X metallic nanocomposite positive electrode material and a sodium ion battery, comprising the following steps:

[0095] (1) Prepare a concentrated hydrochloric acid solution of a certain concentration, add lithium fluoride to the above hydrochloric acid solution and stir for 10-20 minutes until the lithium fluoride is completely dissolved, then slowly add Ti3AlC2 to the solution to prevent violent reaction, and continue stirring for a certain time after the addition is completed. After the etching reaction is completed, the obtained colloidal suspension solution is centrifuged and washed several times with anhydrous ethanol, and the pH of the supernatant is tested until the pH value of the supernatant reaches 6. Then ultrasonically treat it for 60 minutes to make it uniformly dispersed, and Ti3C2T X Nanosheet ethanol solution, and finally Ti3C2T X Ti3C2T can be obtained by vacuum freeze drying of nanoethanol solution X Nanosheet powder.

[0096] (2) T i3C2T X After weighing the nanosheet powder, place it in a beaker containing silver nitrate aqueous solution and seal it with laboratory sealing film and let it stand to promote the adsorption of silver ions. This process was carried out in a dark environment. Soak for 8 hours to allow Ag + Fully adsorbed on Ti3C2T X The solution in the beaker was then irradiated with a laboratory UV lamp for 60 minutes to reduce the Ag + In situ generation of Ag 0 , Ag 0 Successfully in situ deposited on Ti3C2T X On nanosheets;

[0097] (3) According to the stoichiometric ratio of each element in the quaternary material, copper acetate, nickel acetate, ferrous chloride and manganese acetate were weighed and immersed in sodium chloride solution for in-situ oxidation. X The nanocomposite materials were added and immersed for 10 hours to form a X The sodium ion quaternary positive electrode material was generated in situ on the nanosheet and AgCl nanoparticles were successfully deposited. The nanosheet was sealed with a laboratory sealing film and left to stand directly. This process also needed to be operated in a dark environment. m Cu 1-x-y-z Ni x Fe y Mn z O2 on Ti3C2T X The nanosheets were fully reacted and the solution was exposed to ultraviolet light for 60 minutes to remove some of the residual Ag. + Reduced to elemental Ag 0 Then centrifuge and wash with anhydrous ethanol to separate. Finally, vacuum freeze-dry to obtain Na m Cu 1-x-y-z Ni x Fey Mn z O2 / Ag@AgCl / Ti3C2T X metal nanocomposite cathode material.

[0098] (4) The synthesized Na m Cu 1-x-y-z Ni x Fe y Mn z O2 / Ag@AgC l / Ti3C2T X The metal nanocomposite cathode material, conductive agent and binder PVDF are added to the NMP solution in a mass ratio of 8:1:1, fully stirred and mixed to obtain a uniform slurry, then the slurry is uniformly coated on an aluminum foil, and the slurry is placed in a vacuum drying oven at 100°C to obtain a positive electrode sheet.

[0099] (5) The positive electrode sheet in step (4) is paired with a metal sodium negative electrode to assemble a CR2032 type button cell in an inert atmosphere filled glove box to test the electrochemical performance of the composite cathode material.

[0100] Comparative Example 1

[0101] (1) The Ag / Ti3C2T X nanopowder is mixed with Na m Cu 1-x-y-z Ni x Fe y Mn z O2 cathode material is synthesized by a wet method and vacuum freeze-dried to obtain a quaternary Na m Cu 1-x-y-z Ni x Fe y Mn z O2 / Ag / Ti3C2T X nanopowder, conductive agent and binder PVDF are added to the NMP solution in a mass ratio of 8:1:1, fully stirred and mixed to obtain a uniform slurry, then the slurry is uniformly coated on an aluminum foil, and the slurry is placed in a vacuum drying oven at 70-100°C to obtain a positive electrode sheet.

[0102] (2) The positive electrode sheet in step (1) is paired with a metal sodium negative electrode to assemble a CR2032 type button cell in an inert atmosphere filled glove box to test the electrochemical performance of the composite cathode material.

[0103] Comparative Example 2

[0104] (1) The AgCl / Ti3C2T X nanopowder is mixed with Na m Cu1-x-y-z Ni x Fe y Mn z O2 positive electrode material is vacuum freeze-dried after wet synthesis to obtain a quaternary Na m Cu 1-x-y-z Ni x Fe y Mn z O2 / AgCl / Ti3C2T X Nanopowder, conductive agent and binder PVDF are added to NMP solution in a mass ratio of 8:1:1, stirred and mixed to obtain a uniform slurry, then the slurry is uniformly coated on an aluminum foil, and put into a vacuum drying oven to bake at 70-100°C to obtain a positive electrode sheet.

[0105] (2) The positive electrode sheet in step (1) is paired with a metal sodium negative electrode to assemble a CR2032 button cell in an inert atmosphere-filled glove box to test the electrochemical performance of the composite positive electrode material.

[0106] Further, the charge-discharge equipment is used to evaluate the cycle performance of the Na m Cu 1-x-y-z Ni x Fe y Mn z O2 / Ag@AgCl / MXene composite positive electrode material assembled button cell, at the same time, as a comparison, the battery Na m Cu 1-x-y-z Ni x Fe y Mn z O2 / Ag / Ti3C2T X and the Na m Cu 1-x-y-z Ni x Fe y Mn z O2 / AgCl / Ti3C2T X The above performance of the battery, the results are shown in Table 1, at 4.2V voltage, the Na m Cu 1-x-y-z Ni x Fe y Mn z O2 / Ag@AgCl / MXene composite positive electrode material has better 1C discharge capacity and cycle performance than Na m Cu 1-x-y-z Ni x Fe y Mn z O2 / Ag / Ti3C2T X and

[0107] Na m Cu 1-x-y-z N i x Fe y Mn z O2 / AgC l / Ti3C2T X Composite positive electrode material, the electrochemical performance test results after 100 cycles found that Na m Cu 1-x-y-z N i x Fe y Mn z The capacity retention rate of O2 / Ag@AgCl / MXene composite positive electrode material is greater than 80%, which is obviously better than that of Na m Cu 1-x-y-z N i x Fe y Mn z O2 / Ag / Ti3C2T X And

[0108] Na m Cu 1-x-y-z N i x Fe y Mn z O2 / AgC l / Ti3C2T X Positive electrode material, it shows that the first charge-discharge efficiency, rate discharge performance and cycle performance of the composite positive electrode material prepared in examples 1-8 are better than those of the composite positive electrode material in comparative examples 1-2, and the above results show that by surface modification of the quaternary positive electrode material Na m Cu 1-x-y-z Ni x Fe y Mn z O2, including noble metal Ag deposition, AgCl doping and compounding with high conductivity material MXene, the performance is obviously improved.

[0109] Table 1-electrochemical performance test results of examples 1-8 and comparative examples 1-2

[0110]

[0111] From the above table 1, it can be seen that the discharge capacity of the battery made of the positive electrode material prepared in examples 1-8 after 100 cycles and the capacity retention rate after 100 cycles are greater than those of the battery made of the positive electrode material in comparative examples 1-2, so the prepared positive electrode material in the present application can improve the discharge capacity and cycle stability.

[0112] It should be noted that, in this text, the term "comprising", "including" or any other variant thereof is intended to cover a non-exclusive inclusion, so that a process, method, article or system that includes a list of elements not only includes those elements, but also includes other elements not expressly listed, or inherent to such process, method, article or system. Without more limitations, the element defined by the statement "comprising a" does not exclude the presence of other identical elements in the process, method, article or system that includes the element.

[0113] The above-mentioned embodiment numbers of the application are only for description, not representing the advantages and disadvantages of the embodiments.

[0114] The above is only the preferred embodiment of the application, and does not limit the patent scope of the application. Any equivalent structure or equivalent process transformation made by using the content of the application specification and drawings, or directly or indirectly applied in other related technical fields, is also included in the patent protection scope of the application.

Claims

1. A method for preparing a composite positive electrode material, characterized in that: The method comprises the following steps: Step 1: Add a preset mass of lithium fluoride into a concentrated hydrochloric acid solution and dissolve it completely, then slowly add the MXene precursor and stir thoroughly for a preset time to obtain a colloidal suspension solution; Step 2: The colloidal suspension solution is centrifuged and washed with anhydrous ethanol, and the pH value of the supernatant is detected until the pH value reaches 5-10, followed by step-by-step ultrasonic treatment and vacuum freeze-drying to obtain MXene nanosheet powder; Step 3: Place the MXene nanosheet powder in a silver nitrate aqueous solution and soak it in a dark environment for 2 to 12 hours to allow the Ag + Ag is fully adsorbed on the MXene nanosheets and then irradiated with UV light for a preset time to allow the Ag + In situ generation of Ag 0 After irradiation, the Ag / MXene nanocomposite material was obtained by centrifugal washing with anhydrous ethanol and vacuum freeze drying. Step 4: Weigh the preset mass of copper source, nickel source, iron source and manganese source, immerse them in sodium chloride solution, and add the Ag / MXene nanocomposite prepared in step 3, and continue to soak in a dark environment for 2 to 12 hours to in situ generate sodium ion quaternary cathode material on the MXene nanosheets and successfully deposit AgCl nanoparticles, and then irradiate with ultraviolet light for a preset time to make the remaining Ag + In situ generation of Ag 0 After irradiation, Na m Cu 1-x-y- z Ni x Fe y Mn z O2 / Ag@AgCl / MXene metal nanocomposite cathode material, wherein 0.5≤m≤1.5, 0 <x<0.5,0<y<0.5,0<z<1,0<1-x-y-z<1。 2. The method for preparing a composite positive electrode material according to claim 1, wherein: In step 1, the mass volume ratio of lithium fluoride to concentrated hydrochloric acid solution is (1-5) g: (15-100) mL, and the mass fraction of the concentrated hydrochloric acid solution is 34%.

3. The method for preparing a composite positive electrode material according to claim 1, wherein: In step 2, MXene nanosheets including Ti3C2T x 、Nb2CT x 、Mo2CT x 、V2CT x 、Ti2CT x 、Ti2NT x 、V4C3T x 、Nb4C3T x 、Ti3CNT x 、Ta4C3T x and TiNbCT x At least one of .

4. The method for preparing a composite positive electrode material according to claim 1, wherein: In step 2, the time of step-by-step ultrasonication is 10 to 120 minutes.

5. The method for preparing a composite cathode material according to claim 1, wherein: In step 3, the concentration of the silver nitrate aqueous solution is 0.1 mol / L, and the mass volume ratio of the MXene nanosheet powder to the silver nitrate aqueous solution is (10-500) mg: (10-50) mL.

6. The method for preparing a composite cathode material according to claim 1, wherein: In step 4, the copper source includes at least one of copper sulfate, copper chloride, copper nitrate and copper acetate, the nickel source includes at least one of nickel sulfate, nickel chloride, nickel nitrate and nickel acetate, the iron source includes at least one of ferric sulfate and / or ferrous sulfate, ferric chloride and / or ferrous chloride, ferric nitrate and / or ferrous nitrate, ferric citrate and ferric acetate, and the manganese source includes at least one of manganese sulfate, manganese chloride, manganese nitrate and manganese acetate.

7. The method for preparing a composite cathode material according to claim 1, wherein: The UV lamp irradiation time in step 3 and step 4 is 60 minutes respectively.

8. A composite positive electrode material, characterized in that The composite positive electrode material is prepared according to the method for preparing a composite positive electrode material according to any one of claims 1 to 7.

9. A sodium ion battery, characterized in that: The sodium ion battery includes a positive electrode sheet, which is prepared by adding the composite positive electrode material according to claim 8, a conductive agent, and a binder PVDF in a mass ratio of 8:1:1 to an NMP solution and fully stirring and mixing, then evenly coating the mixture on an aluminum foil, and finally baking the mixture in a vacuum drying oven at 70-100°C.

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