Nanostructure composite material, preparation method thereof, electrode and rechargeable battery

Abstract

The invention provides a nano-structure composite material and a preparation method thereof, an electrode and a rechargeable battery, the nano-sheet Cu2O / Co (OH) 2 nanoflower is firstly prepared, and then the CuSe2 / (Cu, Co) Se2 composite nano material is selenized in one step by using a hydrothermal method. Compared with the prior art, the core-shell-nano flaky CuSe2 / (Cu, Co) Se2 nanoflower composite material prepared by the preparation method disclosed by the invention can keep a core-shell structure and a flaky nanoflower structure, is firm in structure, and can provide a large specific surface area and active sites; through the synergistic effect of a heterogeneous interface formed by CuSe2 and (Cu, Co) Se2 and selenium vacancy, under the adaptation of MACC / TGM-NaTFSI electrolyte, the battery has good cycle performance and stable coulombic efficiency, meanwhile, the charge and discharge capacity of the battery is improved, and the charge and discharge efficiency of the battery is improved in electrode process dynamics; the raw materials are low in price, and the synthesis method is batch-controllable.

Description

Technical Field

[0001] This invention belongs to the field of rechargeable battery cathode material technology, specifically relating to a nanostructured composite material and its preparation method, electrode and rechargeable battery. Background Technology

[0002] Developing affordable, high-energy-density rechargeable batteries is a global priority to meet the growing demands of electric transportation and grid energy storage. Currently, commercially available high-energy-density lithium-ion batteries (LIBs) are the mainstream technology, but their high cost and safety concerns pose a disadvantage. In 2015, the price of lithium carbonate, the cathode material for lithium-ion batteries, surged due to the increasing global demand for energy storage applications. Therefore, there is a strong expectation for energy storage technologies that go beyond lithium-ion batteries, possessing high energy density, long cycle life, and, most importantly, low material and manufacturing costs. This has led to research into technologies such as multivalent ions (Mg... 2+ Ca 2+ And Al 3+ There is a strong interest in new battery concepts such as embedded batteries.

[0003] Magnesium metal is a promising anode material for rechargeable batteries, exhibiting a low reduction potential (relative to the standard hydrogen electrode -2.37 V) and high volumetric capacity (3833 mAh cm⁻¹). -3 Magnesium rechargeable batteries (MRBs) possess several advantages, including abundant natural resources and rapid dendrite deposition / exfoliation kinetics. Over the past few years, MRBs have attracted considerable attention, driving the development of novel electrolytes and a fundamental understanding of the electroactive materials within these electrolytes. Despite these advancements, the development of practical MRBs remains significantly hampered by limitations in the selection of magnesium-intercalated cathodes and incompatibility issues between the anode, electrolyte, and cathode.

[0004] Pseudocapacitive magnesium and sodium ion storage technology has recently attracted widespread attention as an alternative to traditional insertion, alloying, and conversion reactions. A hybrid sodium-magnesium (Na / Mg) battery, based entirely on globally abundant and inexpensive materials, is proposed: metallic magnesium as the negative electrode, sodium / magnesium electrolyte, and intercalating / deintercalating Mg... 2+ / Na + The ions act as the positive electrode. This surface or near-surface redox reaction follows reaction kinetics independent of charge diffusion and is independent of the bulk ionic and electronic conductivity of the electrode material. Furthermore, the excellent crystal structure stability exhibited during ion insertion and extraction ensures long-term cycling stability.

[0005] Despite these advantages, the high charge density of magnesium ions (120 C mm) -3This results in a greater Coulombic repulsion between the charge cloud and the host electrode, which in turn leads to a slower redox reaction, thus reducing satisfactory specific capacity, rate performance, and cycle stability. Therefore, improving the performance of rechargeable magnesium / sodium hybrid ion batteries is essential. Summary of the Invention

[0006] The purpose of this invention is to provide a nanostructured composite material and its preparation method. Nanosheet-like Cu₂O / Co(OH)₂ nanoflowers are synthesized using low-cost raw materials, and then CuSe₂ / (Cu,Co)Se₂ composite nanomaterials are obtained through a simple hydrothermal one-step selenization treatment. The preparation method is simple and efficient.

[0007] Another objective of this invention is to provide an electrode prepared using the aforementioned nanostructured composite material as the active material.

[0008] A final objective of this invention is to provide a rechargeable battery comprising electrodes made of the aforementioned nanostructured composite material. The rechargeable battery also includes an ether-modified MACC / TGM-NaTFSI electrolyte for preparing a magnesium / sodium mixed-ion rechargeable battery, thereby improving battery performance.

[0009] The specific technical solution of this invention is as follows:

[0010] A method for preparing a nanostructured composite material includes the following steps:

[0011] Cu2O / Co(OH)2 nanoflower material was dispersed in a solvent to obtain solution A; selenium powder was uniformly mixed in hydrazine hydrate solution to obtain solution B; solution B was added dropwise to solution A, ultrasonically dispersed, and then subjected to hydrothermal reaction to obtain nanosheet-like CuSe2 / (Cu,Co)Se2 nanoflower composite material.

[0012] In solution A: the ratio of Cu2O / Co(OH)2 nanoflower material to solvent is 0.0015-0.003 g / mL, preferably 0.0025 g / mL; the Cu2O / Co(OH)2 nanoflower material is dispersed in the solvent by ultrasonic dispersion for 10-25 min; the volume ratio of water to alcohol is 1-3:1-2, preferably 1:1; the solvent is a mixture of water and alcohol; the water is deionized water, and the alcohol is ethanol; the use of a mixture of water and alcohol in this invention will better disperse the nanocubic flower structure; and the mixing of water and ethanol solutions will change the surface tension of the solution, increasing the surface tension and promoting the reaction.

[0013] The preparation method of the Cu2O / Co(OH)2 nanoflower material includes the following steps:

[0014] 1) After mixing copper salt solution, sodium citrate solution, sodium carbonate solution and glucose solution, dilute with water, age, wash and dry to prepare Cu2O nanoflower precursor;

[0015] 2) Dissolve polyvinylpyrrolidone (PVP) in a mixed solution of ethanol and water, add Cu2O nanoflower precursor and cobalt salt to react, and then add sodium thiosulfate solution dropwise until the solution changes color to obtain nanosheet Cu2O / Co(OH)2 nanoflower precursor material.

[0016] In step 1), the copper salt solution is a copper sulfate solution with a concentration of 0.66-0.70 mol / L, preferably 0.68 mol / L;

[0017] In step 1), the sodium citrate solution has a concentration of 0.72-0.76 mol / L, preferably 0.74 mol / L;

[0018] In step 1), the sodium carbonate solution has a concentration of 1.0-1.4 mol / L, preferably 1.2 mol / L;

[0019] In step 1), the glucose solution has a concentration of 0.8-1.2 mol / L, preferably 1.0 mol / L;

[0020] In step 1), the volume ratio of the copper salt solution, sodium citrate solution, sodium carbonate solution, and glucose solution is 1:1:1:1.4.

[0021] In step 1), deionized water is added for dilution; the copper salt concentration is diluted to 0.033-0.035 mol / L.

[0022] In step 1), the aging temperature is 70-80℃, preferably 75℃, and the aging time is 2-4 h, preferably 3 h; the cleaning and drying process is as follows: cleaning is performed by alternating between deionized water and ethanol 6-8 times, and drying is performed at 60℃ for 12-24 h.

[0023] In step 2), the molecular weight of the polyvinylpyrrolidone is 30,000-80,000, preferably 58,000; the volume ratio of ethanol to deionized water is 1:1; and the amount ratio of polyvinylpyrrolidone to deionized water is 0.06666 g / mL.

[0024] In step 2), the ratio of the Cu2O nanoflower precursor to water is 0.003-0.005 g / mL, preferably 0.004 g / mL;

[0025] In step 2), the ratio of cobalt salt to water is 0.001-0.002 g / mL, preferably 0.00136 g / mL; the cobalt salt is CoCl2·6H2O; the mass ratio of Cu2O nanoflower precursor to CoCl2·6H2O is 2-4:1, preferably 3:1; and the reaction time is 10 min.

[0026] In step 2), the concentration of the sodium thiosulfate solution is 0.8-1.2 mol / L, preferably 1.0 mol / L; the volume ratio of the sodium thiosulfate solution to water is 4:5.

[0027] In step 2), the dripping is done at a rate of one drop per second; sodium thiosulfate acts as a complexing agent and solvent, and the thiosulfate ion has a strong coordinating ability, which can form a stable [Cu(S2O3)2] with cuprous ions. 3- Simultaneously, the generated OH- reacts with cobalt ions to produce Co(OH)2 reactants;

[0028] In step 2), after the reaction is complete, the product is washed and dried. The washing process involves washing with deionized water and ethanol alternately 6-8 times, and the drying conditions are drying at 60℃ for 12-24 hours.

[0029] In solution B: the selenium powder is mixed in the hydrazine hydrate solution at a water bath stirring temperature of 70-90℃, preferably 80℃; the mass percentage concentration of the hydrazine hydrate solution is 40-80 wt%, preferably 50 wt%; the ratio of selenium powder to hydrazine hydrate is 0.02-0.05 g / mL, preferably 0.04 g / mL; the stirring conditions refer to magnetic stirring at a speed of 200-300 rpm for a stirring time of 15-20 min; the hydrazine hydrate acts as a reducing agent and an antioxidant.

[0030] The mass ratio of selenium powder in solution B to Cu2O / Co(OH)2 nanoflower material in solution A is 1-3:1-2, preferably 2:1.

[0031] Solution B is added dropwise to solution A at a rate of 1 drop / second.

[0032] Add solution B dropwise to solution A and ultrasonically disperse for 10-15 minutes;

[0033] In the preparation method of nanostructured composite materials, the hydrothermal reaction temperature is 160-200℃, preferably 180℃, and the reaction time is 10-14 h, preferably 12 h;

[0034] After the hydrothermal reaction is completed, the product is washed and then dried. The washing is performed by washing with water 6-8 times. The drying is performed at 60-80°C in the air, preferably at 60°C.

[0035] In the preparation method of this invention, a core-shell nanosheet-like Cu2O / Co(OH)2 nanoflower precursor is first formed, and then further selenization treatment is performed using selenium powder as an oxidant under certain hydrothermal conditions to carry out a redox reaction, resulting in a core-shell heterojunction CuSe2 / (Cu,Co)Se2 nanoflower-sheet composite material. The obtained core-shell heterojunction CuSe2 / (Cu,Co)Se2 nanoflower-sheet composite material has a hard structure, is not easily oxidized, and is easy to store. The surface has a large number of nanosheet structures and the internal flower structure has a larger specific surface area than a single nanoflower structure, which increases the number of active sites. The uniform sheet structure increases the transfer of electrons and ions, provides more transport channels, and its structure is stable, providing a large specific surface area and active sites. The core-shell structure can effectively alleviate the volume change during cycling, improve the long-cycle stability of the battery, provide high reversibility, and improve coulombic efficiency and rate performance. Furthermore, the heterojunction formed at the interface between CuSe2 and (Cu,Co)Se2 phases, through the synergistic effect of the built-in electric field, interface effect, and structural stabilization, causes the atomic arrangement and electronic structure at the heterojunction interface to be restructured, forming a large number of highly active catalytic sites, effectively reducing Mg... 2+ / Na + The insertion / extraction reaction barrier results in higher reversible capacity and lower polarization voltage. Furthermore, the material is simple to prepare and has low cost.

[0036] This invention provides a nanostructured composite material prepared using the above-described method. The prepared nanostructured composite material is a core-shell nanosheet-like CuSe2 / (Cu,Co)Se2 nanoflower composite material with the morphology of uniform four-petaled flower-like in-situ long sheet-like structures with a size of 1-2 μm, and the sheet-like structure size is 50-100 nm. The core-shell nanoflower structure and the surface sheet-like structure reduce the Mg content. 2+ / Na + The volume change caused by extraction reduces the pathways for electron and ion transport. Simultaneously, it increases the number of active sites for ions and electrons during charge and discharge, accelerating the redox reaction process and resulting in stable cycle performance and excellent rate performance.

[0037] The present invention provides an electrode, which is prepared by using the above-mentioned nanostructured composite material as the active material to obtain a magnesium / sodium hybrid ion battery cathode.

[0038] This invention provides a rechargeable battery comprising electrodes made of the aforementioned nanostructured composite material. The rechargeable battery also includes an ether-modified MACC / TGM-NaTFSI electrolyte for preparing a magnesium / sodium mixed-ion rechargeable battery, thereby improving battery performance.

[0039] The preparation method of the MACC / TGM-NaTFSI electrolyte includes the following steps:

[0040] A. Dissolve magnesium salt and aluminum salt in triethylene glycol dimethyl ether (TGM) solvent, and stir to form a MACC / TGM solution;

[0041] B. Add NaTFSI sodium salt to the MACC / TGM solution, stir to dissolve, and prepare a MACC / TGM-NaTFSI mixed ion electrolyte;

[0042] In step A, the magnesium salt is anhydrous magnesium chloride; the aluminum salt is anhydrous aluminum chloride; the concentration of the magnesium salt in triethylene glycol dimethyl ether is 0.1-0.3 mol / L, preferably 0.2 mol / L; the concentration of the aluminum salt in triethylene glycol dimethyl ether is 0.1-0.3 mol / L, preferably 0.2 mol / L; and the time for forming the MACC / TGM solution after stirring is 10-14 h, preferably 12 h.

[0043] In step B, the concentration of NaTFSI in the MACC / TGM-NaTFSI solution is 0.2-0.6 mol / L, preferably 0.4 mol / L, and the stirring and dissolving time is 10-14 h, preferably 12 h.

[0044] In the electrolyte preparation method of this invention, the prepared electrolyte combines the advantages of high solubility and high conductivity. A highly soluble boron-free bis(trifluoromethanesulfonyl)imine (TFSI) sodium salt provides a sodium ion source for dual-ion batteries; by controlling the ion ratio of the additives, a [Mg2Cl2][AlCl4]2 (MACC) / triethylene glycol dimethyl ether (TGM)-NaTFSI electrolyte with a wide voltage window, low overvoltage, and reversible magnesium plating / stripping is prepared.

[0045] The specific preparation method of the magnesium / sodium mixed-ion rechargeable battery is as follows:

[0046] S1. The prepared core-shell heterojunction CuSe2 / (Cu,Co)Se2 nanoflower-plate composite material is used as the active material. It is mixed with conductive carbon black and polyvinylidene fluoride (PVDF) in a mass ratio of 7.5:1.5:1 and then dispersed in N-methylpyrrolidone (NMP). After magnetic stirring for 8-10 hours, the uniformly mixed slurry is coated onto copper foil using a coater. It is then placed in a vacuum drying oven at 60-80℃ and dried for 24-36 hours. After drying, it is pressed into tablets using a tablet press and then cut into small circular electrode sheets with a diameter of 12 mm using a cutting machine.

[0047] S2. Assemble the prepared electrode sheets into a button cell in a glove box filled with high-purity argon gas (Super 1220 / 750 / 900, water and oxygen values ​​≤0.01ppm). Use the prepared MACC / TGM-NaTFSI electrolyte. The magnesium foil has a purity of Mg ≥99.99%, a thickness of 50 μm, and is cut into circular pieces with a diameter of 16 mm and an area of ​​2.0 cm². 2 The copper sheet has a purity of Cu ≥ 99.99%, a thickness of 0.5 mm, and is cut to the size of the electrode sheet; the loading mass of the active material is 1.2 mg / cm³. -2 Glass fiber membrane (GF / F) is used as the separator; the magnesium-based electrolyte content of each coin cell is approximately 120 μL.

[0048] S3. The specific method for assembling the battery is as follows: Add one or two drops of electrolyte to the positive electrode casing, then place the electrode plate. Next, add two to three drops of electrolyte and place glass fiber. Add two or three drops of electrolyte to the glass fiber and place a magnesium sheet as the counter electrode. Then, place the gasket and spring, cover with the negative electrode casing, and press and seal the battery using a hydraulic press. Let it stand for 4-10 hours to complete the battery assembly. Symmetrical batteries use magnesium foil (circular pieces with a diameter of 16 mm) and copper foil as counter electrodes, respectively, in button cells. Asymmetrical batteries use magnesium foil and copper foil as counter electrodes, respectively, in button cells, and undergo cycle testing.

[0049] Transition metal selenides have wide intergranular spacing and strong chemical bonds, which is beneficial to Mg. 2+ and Na + The reversible phase intersection accelerates ion reaction kinetics. Simultaneously, the prepared core-shell heterostructure CuSe2 / (Cu,Co)Se2 nanoflower-plate composite material, combined with a modified highly soluble electrolyte, utilizes Se... 2- The intercalated cathode for soft anions can break down Mg 2+ The core-shell structure and flower-like structure mitigate the migration barrier of Mg, thus improving the overall structural stability. 2+ / Na + The volume change induced by extraction reduces the pathways for electron and ion transport. Furthermore, the synergistic effect of the CuSe2 / (Cu,Co)Se2 composite material with its heterogeneous interface and the introduced selenium vacancies effectively modulates the electronic structure of the material, further enhancing the activity of the Cu-Se / Co-Se bonds, promoting charge transfer, forming a built-in electric field, and increasing Mg content. 2+ / Na + Storage.

[0050] This invention presents a high-performance magnesium / sodium (Mg / Na) hybrid ion battery using a core-shell heterojunction CuSe2 / (Cu,Co)Se2 nanoflower-plate composite cathode and a modified MACC / TGM-NaTFSI electrolyte. Currently, three electrolytes are mainly used: [Mg2Cl2][AlCl4]2 + NaAlCl4 in dimethoxymethane, Mg(BH4)2 / Mg(TFSI)2 + NaBH4 in DGM, and Mg(HMD)2 / AlCl3 + NaTFSI in DGM. This invention makes some modifications to these electrolytes, improves the concentration of MgCl2 and AlCl3 in TGM, explores their internal structure, and studies the solubility of NaTFSI sodium salt in TGM, thereby improving the electrochemical performance of the battery.

[0051] To address the problems existing in the current technology, developing high-performance cathode materials and highly adaptable mixed-ion electrolytes is a major challenge in the development of magnesium / sodium hybrid-ion batteries. This invention utilizes MACC / TGM-NaTFSI electrolyte and CuSe2 / (Cu,Co)Se2 composite material to prepare a magnesium / sodium hybrid-ion battery cathode material, thereby obtaining a high-performance magnesium / sodium (Mg / Na) hybrid-ion battery with a multi-stage CuSe2 / (Cu,Co)Se2 composite material cathode and a modified electrolyte.

[0052] This invention utilizes a core-shell heterojunction CuSe2 / (Cu,Co)Se2 nanoflower-plate composite material to fabricate the cathode material for a magnesium / sodium hybrid ion battery, paired with a MACC / TGM-NaTFSI electrolyte. The magnesium / sodium hybrid ion battery using CuSe2 / (Cu,Co)Se2 as the cathode, operating with the modified electrolyte, exhibits high energy density, high stability, and large reversible capacity. It accelerates the reaction kinetics of magnesium and sodium ions, improving the safety and long cycle life of the dual-ion battery, laying a solid foundation for the practical application of magnesium / sodium hybrid ion batteries.

[0053] Compared with existing technologies, this method has the following advantages: the core-shell-nanosheet CuSe2 / (Cu,Co)Se2 nanoflower composite cathode can well maintain the core-shell structure and the sheet-like nanoflower structure, with a robust structure that can provide a large specific surface area and active sites; the prepared CuSe2 / (Cu,Co)Se2 composite material has stable electrochemical performance, and the heterogeneous interface formed by CuSe2 and (Cu,Co)Se2 and the synergistic effect of selenium vacancies, under the adaptation of MACC / TGM-NaTFSI electrolyte, enable the battery to have good cycle performance and stable coulombic efficiency, while improving the charge and discharge capacity of the battery and enhancing the charge and discharge efficiency of the battery in terms of electrode process kinetics; the raw materials are inexpensive and the synthesis method is batch controllable. Attached Figure Description

[0054] Figure 1 SEM image of the Cu2O precursor prepared in Example 1;

[0055] Figure 2 SEM image of the Cu2O / Co(OH)2 precursor prepared in Example 1;

[0056] Figure 3 TEM image of the Cu2O / Co(OH)2 precursor prepared in Example 1;

[0057] Figure 4 The image shows a SEM image of the CuSe2 / (Cu,Co)Se2 composite material prepared in Example 1.

[0058] Figure 5 SEM image of the Cu2O precursor prepared in Example 2;

[0059] Figure 6 SEM image of the Cu2O / Co(OH)2 precursor prepared in Example 2;

[0060] Figure 7 TEM image of the Cu2O / Co(OH)2 precursor prepared in Example 2;

[0061] Figure 8 SEM image of the CuSe2 / (Cu,Co)Se2 composite material prepared in Example 2;

[0062] Figure 9 SEM image of the nanoflower Cu2O precursor prepared in Example 3;

[0063] Figure 10 TEM image of the nanoflower Cu2O precursor prepared in Example 3;

[0064] Figure 11 SEM image of the core-shell Cu2O / Co(OH)2 precursor prepared in Example 3;

[0065] Figure 12 SEM image of the core-shell heterojunction CuSe2 / (Cu,Co)Se2 nanoflower-sheet composite material prepared in Example 3;

[0066] Figure 13 TEM image of the core-shell heterojunction CuSe2 / (Cu,Co)Se2 nanoflower-sheet composite material prepared in Example 3;

[0067] Figure 14 The image shows the XRD pattern of the core-shell heterojunction CuSe2 / (Cu,Co)Se2 nanoflower-sheet composite material prepared in Example 3.

[0068] Figure 15 EPR image of the core-shell heterojunction CuSe2 / (Cu,Co)Se2 nanoflower-plate composite material prepared in Example 3;

[0069] Figure 16 The XANES spectrum of the core-shell heterojunction CuSe2 / (Cu,Co)Se2 nanoflower-plate composite material prepared in Example 3 is shown.

[0070] Figure 17 The core-shell heterojunction CuSe2 / (Cu,Co)Se2 nanoflower-sheet composite material prepared in Example 3 was used as the cathode material for a magnesium / sodium hybrid ion battery at 0.5 mA cm⁻¹. -2 The deposition / dissolution cycle performance of symmetrical cells under different electrolytes was tested at different current densities.

[0071] Figure 18 The core-shell heterojunction CuSe2 / (Cu,Co)Se2 nanoflower-sheet composite material prepared in Example 3 was used as the cathode material for a magnesium / sodium hybrid ion battery at 0.5 mA cm⁻¹. -2 Cyclic performance of Mg||Cu asymmetric cells in MACC / TGM-NaTFSI electrolyte was obtained at current density;

[0072] Figure 19 The core-shell heterojunction CuSe2 / (Cu,Co)Se2 nanoflower-plate composite material prepared in Example 3 was used as a cathode material for a magnesium / sodium hybrid ion battery in the range of 0.4-10.0 mA cm⁻¹. -2 The rate performance of the Mg||Cu asymmetric cell in MACC / TGM-NaTFSI electrolyte was tested at the current density.

[0073] Figure 20 The core-shell heterojunction CuSe2 / (Cu,Co)Se2 nanoflower-plate composite material prepared in Example 3 was used as a cathode material for a magnesium / sodium hybrid ion battery in the range of 0.4-10.0 mA cm⁻¹. -2 Comparison of coulombic efficiency tests of Mg||Cu asymmetric cells under different electrolytes at current densities;

[0074] Figure 21 The core-shell heterojunction CuSe2 / (Cu,Co)Se2 nanoflower-sheet composite material and CuSe2 nanoflowers prepared in Example 3 and Comparative Example 1 were used as cathode materials for magnesium / sodium hybrid ion batteries at 0.5 A g. -1 Comparison of cycling performance under current density in MACC / TGM-NaTFSI electrolyte;

[0075] Figure 22The core-shell heterojunction CuSe2 / (Cu,Co)Se2 nanoflower-plate composite material prepared in Example 3 was used as the cathode material for a magnesium / sodium hybrid ion battery at 2.0 A g. -1 Comparison of cycling performance in different electrolytes at different current densities;

[0076] Figure 23 The core-shell heterojunction CuSe2 / (Cu,Co)Se2 nanoflower-plate composite material prepared in Example 3 was used as a cathode material for magnesium / sodium hybrid ion batteries in different electrolytes ranging from 0.1 to 10.0 A g. -1 Rate performance test results under current density;

[0077] Figure 24 The core-shell heterojunction CuSe2 / (Cu,Co)Se2 nanoflower-plate composite material prepared in Example 3 was used as the cathode material for a magnesium / sodium hybrid ion battery at 4.0 A g. -1 Long-cycle performance in MACC / TGM-NaTFSI electrolyte at current density;

[0078] Figure 25 The core-shell heterojunction CuSe2 / (Cu,Co)Se2 nanoflower-plate composite material prepared in Example 3 was used as the cathode material for a magnesium / sodium hybrid ion battery in MACC / TGM-NaTFSI electrolyte at 2.0 A g. -1 Cyclic performance test results at current density under extreme conditions of 50°C. Detailed Implementation

[0079] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0080] Unless otherwise specified, all test materials and reagents used in the following examples are commercially available.

[0081] Unless otherwise specified in the embodiments, the techniques or conditions described in the literature in this field or in accordance with the product manual may be followed.

[0082] Example 1 (as a comparison)

[0083] A method for preparing a nanostructured composite material includes the following steps:

[0084] 1) Preparation of Cu2O precursor:

[0085] At room temperature, 4 mL of 0.66 mol / L copper sulfate solution, 4 mL of 0.72 mol / L sodium citrate solution, 4 mL of 1.0 mol / L sodium carbonate solution, and 5.6 mL of 0.8 mol / L glucose solution were mixed thoroughly at 75 ℃. The mixture was then diluted with deionized water to 80 mL and allowed to stand for 3 hours. After the reaction was complete, the mixture was cooled, centrifuged at 8000 rpm, washed four times with deionized water and twice with ethanol, and dried in a 60 ℃ oven for 12 h to obtain the Cu₂O precursor. Its SEM image is shown below. Figure 1 As shown in the figure, its shape is a relatively non-uniform cubic structure, and there are Cu2O precursor impurities with uneven morphology. During the reaction process, the reactions of each solution are not uniform and are insufficient to reach the optimal reaction concentration, so the product shape is not a four-petal flower shape.

[0086] 2) Preparation of Cu2O / Co(OH)2 precursor:

[0087] 3.333 g of PVP (molecular weight 30000) was weighed and dissolved in 100 mL of a mixed solution of ethanol and deionized water (volume ratio of ethanol to deionized water 1:1). Then, 0.2 g of Cu₂O precursor and 0.068 g of CoCl₂·6H₂O were added. After stirring for 10 min, 40 mL of 0.8 mol / L sodium thiosulfate solution was added dropwise at a rate of one drop per second. The reaction proceeded until color change, followed by centrifugation at 8000 rpm. The sample was washed four times with deionized water and twice with ethanol, and then dried in a 60 ℃ oven for 12 h to obtain the Cu₂O / Co(OH)₂ precursor. Its SEM image is shown below. Figure 2 As shown, its TEM image is as follows Figure 3 As shown in the figure, the sheet-like structure on the nanocube is obvious, but the interior is a solid structure. This is because the concentration of sodium thiosulfate is not the optimal reaction concentration, which is insufficient to react with part of the Cu2O nanostructure.

[0088] 3) Preparation of CuSe2 / (Cu,Co)Se2:

[0089] Solution A was prepared by ultrasonically dispersing 0.1 g of Cu₂O / Co(OH)₂ precursor in a mixture of 20 mL water and 20 mL anhydrous ethanol for 10 min. Solution B was prepared by ultrasonically dispersing 0.2 g of Se powder in 5 mL of hydrazine hydrate solution (50 wt%). Solution B was obtained by stirring in an 80℃ water bath for 15 min at 300 rpm. Solution B was then added dropwise to solution A under ultrasonic conditions for 10 min. The mixture was then placed in a 50 mL Teflon-lined stainless steel autoclave and reacted at 160℃ for 12 h. After cooling, the mixture was washed six times alternately with deionized water and ethanol, and dried in a 60℃ oven for 12 hours. The SEM image is shown below. Figure 4 As shown, CuSe2 / (Cu,Co)Se2 composite material was prepared, but the flower-like structure was not uniformly formed.

[0090] Example 2 (as a comparison)

[0091] A method for preparing a nanostructured composite material includes the following steps:

[0092] 1) Preparation of Cu2O precursor:

[0093] At room temperature, 4 mL of 0.70 mol / L copper sulfate solution, 4 mL of 0.76 mol / L sodium citrate solution, 4 mL of 1.4 mol / L sodium carbonate solution, and 5.6 mL of 1.2 mol / L glucose solution were mixed thoroughly at 80 °C. The mixture was then diluted to 80 mL with deionized water and allowed to stand for 3 hours. After the reaction was complete, the mixture was cooled, centrifuged at 8000 rpm, washed four times with deionized water and twice with ethanol, and dried in a 60 °C oven for 12 h to obtain the Cu₂O precursor. Its SEM image is shown below. Figure 5 As shown in the figure, its shape is a mixture of non-uniform cubic and flower-like structures; the reason is that the reaction concentration is not optimal, so the product shape is not uniform.

[0094] 2) Preparation of Cu2O / Co(OH)2 precursor:

[0095] 3.333 g of PVP (molecular weight 80,000) was weighed and dissolved in 100 mL of a mixed solution of ethanol and deionized water (volume ratio of ethanol to deionized water 1:1). Then, 0.2 g of Cu₂O precursor and 0.068 g of CoCl₂·6H₂O were added. After stirring for 10 min, 40 mL of 1.2 mol / L sodium thiosulfate solution was added dropwise at a rate of one drop per second. The reaction proceeded until color change, followed by centrifugation at 8000 rpm. The sample was washed four times with deionized water and twice with ethanol, and then dried in a 60℃ oven for 12 h to obtain the Cu₂O / Co(OH)₂ precursor. Its SEM image is shown below. Figure 6 As shown, its TEM image is as follows Figure 7 As shown in the figure, the interior of the nanocube is hollow because the concentration of sodium thiosulfate is not the optimal reaction density. All the Cu2O precursor is reacted, leaving only the Co(OH)2 precursor.

[0096] 3) Preparation of CuSe2 / (Cu,Co)Se2 composite material:

[0097] Solution A was prepared by ultrasonically dispersing 0.1 g of Cu₂O / Co(OH)₂ precursor in a mixture of 20 mL water and 20 mL anhydrous ethanol for 10 min. Solution B was prepared by ultrasonically dispersing 0.2 g of Se powder in 5 mL of hydrazine hydrate solution (50 wt%). Solution B was obtained by stirring in an 80℃ water bath for 15 min at 300 rpm. Solution B was then added dropwise to solution A under ultrasonic conditions for 10 min. The mixture was then placed in a 50 mL Teflon-lined stainless steel autoclave and reacted at 200℃ for 12 h. After cooling, the mixture was washed six times alternately with deionized water and ethanol, and dried in a 60℃ oven for 12 hours. The SEM image is shown below. Figure 8 As shown, CuSe2 / (Cu,Co)Se2 composite material was prepared, but because the reaction temperature was not the optimal reaction temperature, the surface nanosheet structure melted, and the nanoflower structure was unevenly formed, resulting in agglomeration.

[0098] Example 3 (Optimal Reaction Conditions)

[0099] A method for preparing a nanostructured composite material includes the following steps:

[0100] 1) Preparation of Cu2O precursor:

[0101] At room temperature, 4 mL of 0.68 mol / L copper sulfate solution, 4 mL of 0.74 mol / L sodium citrate solution, 4 mL of 1.2 mol / L sodium carbonate solution, and 5.6 mL of 1.0 mol / L glucose solution were mixed thoroughly at 75 °C. The mixture was then diluted with deionized water to 80 mL and allowed to stand for 3 hours. After the reaction was complete, the mixture was cooled, centrifuged at 8000 rpm, washed four times with deionized water and twice with ethanol, and dried in a 60 °C oven for 12 h to obtain the Cu₂O precursor. Its SEM image is shown below. Figure 9 As shown in the figure and TEM image Figure 10 As shown in the figure, its shape is a uniform four-petal flower-like structure. Because the reaction conditions are the optimal reaction concentration and reaction time, the shape is uniform.

[0102] 2) Preparation of Cu2O / Co(OH)2 precursor:

[0103] 3.333 g of PVP (molecular weight 58000) was weighed and dissolved in 100 mL of a mixed solution of ethanol and deionized water (volume ratio of ethanol to deionized water 1:1). Then, 0.2 g of Cu₂O precursor and 0.068 g of CoCl₂·6H₂O were added. After stirring for 10 min, 40 mL of 1.0 mol / L sodium thiosulfate solution was added dropwise at a rate of one drop per second. The reaction proceeded until color change, followed by centrifugation at 8000 rpm. The sample was washed four times with deionized water and twice with ethanol, and then dried in a 60℃ oven for 12 h to obtain the Cu₂O / Co(OH)₂ precursor. Its SEM image is shown below. Figure 11 As shown in the figure, the interior of the nanoflower-like structure is a core-shell structure, and the surface lamellar structure is uniform. This is because the dosage ratio and reaction concentration are optimal, resulting in a uniform product shape.

[0104] 3) Preparation of CuSe2 / (Cu,Co)Se2 composite material:

[0105] Solution A was prepared by ultrasonically dispersing 0.1 g of Cu₂O / Co(OH)₂ precursor in a mixture of 20 mL water and 20 mL anhydrous ethanol for 10 min. Solution B was prepared by ultrasonically dispersing 0.2 g of Se powder in 5 mL of hydrazine hydrate solution (50 wt%). Solution B was obtained by stirring in an 80 °C water bath for 15 min at 300 rpm. Solution B was then added dropwise to solution A under ultrasonic conditions for 10 min. The mixture was then placed in a 50 mL Teflon-lined stainless steel autoclave and reacted at 180 °C for 12 h. After cooling, the mixture was washed six times alternately with deionized water and ethanol, and dried in a 60 °C oven for 12 h. The SEM image is shown below. Figure 12 As shown, the CuSe2 / (Cu,Co)Se2 composite material was prepared, and its TEM image is shown below. Figure 13 As shown in the figure, its micro / nano flower-like structure is well-preserved, and it can be seen that sheet-like structures are grown in situ on the nanoflowers, exhibiting a core-shell structure; furthermore, its XRD pattern is shown in the figure. Figure 14 As shown, it conforms to JCPDS Joint Committee on Diffraction Standards numbers 26-1115 (CuSe2) and 25-0309 [(Cu,Co)Se2)], respectively, and no other impurities are formed. The principle of the selenization process (cation interdiffusion and heterojunction formation): At high temperature, Cu... + and Co 2+ The ions possess a certain migration ability within the formed selenide lattice; a portion of the Co... 2+ Diffusion into the CuSe2 lattice, replacing part of the Cu + The location; at the same time, a portion of Cu + It may also diffuse into the CuSe2 lattice, thus forming a CuSe2 / (Cu,Co)Se2 heterojunction. Its electron paramagnetic response (EPR) spectrum is shown below. Figure 15 As shown, the CuSe2 / (Cu,Co)Se2 composite material exhibits an EPR signal at g=2.003, corresponding to the unpaired electrons trapped by Se vacancies, indicating that it is feasible to construct heterointerfaces and introduce vacancies to improve the electrochemical performance of electrode materials.

[0106] Comparative Example 1 (as a comparison)

[0107] A method for preparing CuSe2 nanoflower materials includes the following steps:

[0108] 1) Same as step 1) in Example 3.

[0109] 2) Preparation of CuSe2 materials:

[0110] 0.1 g of Cu2O precursor was ultrasonically dispersed in a mixture of 20 mL of water and 20 mL of anhydrous ethanol for 10 min to form solution A; 0.2 g of Se powder was weighed and added to 5 mL of hydrazine hydrate solution with a mass percentage concentration of 50 wt%; after stirring in an 80 ℃ water bath for 15 min, solution B was obtained at a stirring speed of 300 rpm; under ultrasonic conditions, solution B was added to solution A drop by drop every second, and ultrasonication was continued for 10 min. The mixture was then placed in a 50 mL Teflon-lined stainless steel autoclave and reacted at 180 ℃ for 12 h; after cooling, the mixture was washed 6 times alternately with deionized water and ethanol, and dried in an oven at 60 ℃ for 12 hours to obtain CuSe2 as a comparative material for CuSe2 / (Cu,Co)Se2 composite material.

[0111] Compared to Comparative Example 1 (single CuSe2), the CuSe2 / (Cu,Co)Se2 heterojunction prepared in Example 3 exhibited a significantly enhanced EPR signal intensity (e.g., Figure 15 This directly confirms the existence of a higher concentration of selenium vacancies at the heterojunction interface, which greatly improves the intrinsic electronic conductivity of the material.

[0112] Meanwhile, its X-ray near-edge absorption structure (XANES) reveals the atomic-scale electronic structure and coordination information of the CuSe2 / (Cu,Co)Se2 heterostructure, such as... Figure 16 As shown. Figure 16 In this paper, Cu foil and Cuo are standard substances, CuSe2 was prepared in Comparative Example 1, and CuSe2 / (Cu,Co)Se2 was prepared in Example 3.

[0113] Example 4 (as a comparison)

[0114] The application of a nanostructured composite material in batteries, specifically as an active material in the preparation of a magnesium / sodium hybrid ion battery cathode, thereby preparing a magnesium / sodium hybrid ion rechargeable battery, including an electrolyte.

[0115] Specifically, the core-shell heterojunction CuSe2 / (Cu,Co)Se2 nanoflower-plate composite material prepared in Example 3 was used as the active material. It was mixed with conductive carbon black and PVDF in a mass ratio of 7.5:1.5:1 and then dispersed in NMP. After magnetic stirring for 8 hours, the uniformly mixed slurry was coated onto copper foil using a coater. It was then placed in a vacuum drying oven at 80 °C and dried for 24 hours. After drying, it was pressed into a tablet using a tablet press and then cut into a small circular electrode sheet using a cutting machine.

[0116] The prepared electrode sheets were assembled into button batteries in a glove box filled with high-purity argon gas (water and oxygen values ​​≤0.01 ppm). Magnesium / sodium mixed-ion battery electrolyte: A 0.2 M MACC / TGM single-salt electrolyte was prepared by stirring and dispersing AlCl3 and MgCl2 in triethylene glycol dimethyl ether (TGM).

[0117] Example 5 (as a comparison)

[0118] The application of a nanostructured composite material in batteries, specifically as an active material in the preparation of a magnesium / sodium hybrid ion battery cathode, thereby preparing a magnesium / sodium hybrid ion rechargeable battery, including an electrolyte.

[0119] Specifically, the electrode sheets obtained in Example 4 were assembled into button batteries in a glove box filled with high-purity argon gas (water and oxygen values ​​≤0.01 ppm). The magnesium / sodium mixed-ion battery electrolytes were as follows:

[0120] 1) AlCl3 and MgCl2 were dispersed in dimethyl ether (DME) to prepare MACC / DME. NaTFSI sodium salt was added to prepare a 0.2 M MACC / DME-0.4 M NaTFSI mixed ionic electrolyte.

[0121] 2) AlCl3 and MgCl2 were dispersed in diethylene glycol dimethyl ether (DGM) to prepare MACC / DGM. NaTFSI sodium salt was added to prepare a 0.2 M MACC / DGM-0.4 M NaTFSI mixed ionic electrolyte.

[0122] 3) AlCl3 and MgCl2 were stirred and dispersed in tetraethylene glycol dimethyl ether (TGDE) to prepare MACC / TGDE. NaTFSI sodium salt was added to prepare a 0.2 M MACC / TGDE-0.4 M NaTFSI mixed ionic electrolyte.

[0123] Example 6 (Optimal Electrolyte)

[0124] The application of a nanostructured composite material in batteries, specifically as an active material in the preparation of a magnesium / sodium hybrid ion battery cathode, thereby preparing a magnesium / sodium hybrid ion rechargeable battery, including an electrolyte.

[0125] Specifically, the electrode sheets obtained in Example 4 were assembled into button batteries in a glove box filled with high-purity argon gas (water and oxygen values ​​≤0.01 ppm). The magnesium / sodium mixed-ion battery electrolyte was prepared as follows:

[0126] A. Anhydrous aluminum chloride and anhydrous magnesium chloride were dissolved in triethylene glycol dimethyl ether solvent, with an anhydrous aluminum chloride concentration of 0.2 mol / L and anhydrous magnesium chloride concentration of 0.2 mol / L. After stirring for 12 h, a MACC / TGM solution was formed.

[0127] B. Add sodium NaTFSI to the MACC / TGM solution with a NaTFSI concentration of 0.4 mol / L. After stirring and dissolving for 12 h, prepare a 0.2 M MACC / TGM-0.4 M NaTFSI electrolyte.

[0128] Example 7

[0129] The application of a nanostructured composite material in batteries, specifically as an active material in the preparation of a magnesium / sodium hybrid ion battery cathode, thereby preparing a magnesium / sodium hybrid ion rechargeable battery.

[0130] Specifically, the electrode sheets obtained in Example 4 were assembled into button batteries in a glove box filled with high-purity argon gas (water and oxygen values ​​≤0.01 ppm). The magnesium / sodium mixed-ion battery electrolyte was prepared using the same method as in Example 6.

[0131] The magnesium foil used has a purity of Mg ≥ 99.99%, a thickness of 50 μm, and is cut to the size of a spacer. The copper sheet has a purity of Cu ≥ 99.99%, a thickness of 0.5 mm, and is cut to the size of an electrode sheet.

[0132] The specific method for assembling the battery is as follows: After adding one drop of electrolyte to the positive electrode shell, place the electrode plate, then add two drops of electrolyte and place the glass fiber. After adding two or three drops of electrolyte to the glass fiber, place the magnesium sheet as the counter electrode. Then place the gasket and spring sheet, cover the negative electrode shell, press and seal the battery with a hydraulic press, and leave it for 10 hours to complete the battery assembly.

[0133] The deposition / dissolution cycle performance of the symmetric cell Mg anode was tested using the MCC / TGM single-ion electrolyte of Example 4, the MCC / DME-NaTFSI, MCC / DGM-NaTFSI, and MCC / TGDE-NaTFSI of Example 5, and the MCC / TGM-NaTFSI electrolyte of Example 6. The results are as follows: Figure 17 As shown, the symmetric Mg|Mg cell using MACC / TGM electrolyte exhibits a high overvoltage, indicating that metallic Mg cannot be completely reversibly electroplated / stripped in a sodium-free electrolyte. After cycling stabilization with the addition of NaTFSI salt, the overvoltage is maintained at 400 mV, demonstrating better Mg deposition / dissolution behavior compared to other electrolytes. Meanwhile, the results for the Mg||Cu asymmetric cell under MACC / TGM-NaTFSI electrolyte conditions are as follows... Figure 18As shown in the figure, its coulombic efficiency exceeds 94% after 400 hours of cycling, and its cycling performance was tested at different current densities, with the results as follows. Figure 19 As shown, at 10 mA cm -2 Reversible magnesium deposition / dissolution was achieved even at ultra-high current densities, demonstrating the excellent cycle stability of the magnesium / sodium hybrid ion battery in the MACC / TGM-NaTFSI electrolyte. Furthermore, the coulombic efficiencies of different electrolytes in Mg||Cu asymmetric batteries were compared, with results as follows: Figure 20 As shown, the coulombic efficiency of the MACC / TGM-NaTFSI electrolyte is 96.17%, which is far superior to other electrolytes.

[0134] Cyclic performance of CuSe2 and CuSe2 / (Cu,Co)Se2 composites (Comparative Example 1 and Example 3), compared with CuSe2 material alone, at 0.5 A g -1 At current density, the CuSe2 / (Cu,Co)Se2 composite material exhibited higher and more stable cycling performance, indicating that the synergistic effect of the heterogeneous interface of the composite material and the introduction of selenium vacancies jointly influences the cycle capacity of the battery under highly compatible salt-in-water electrolyte conditions. The results are as follows: Figure 21 As shown, the main manifestations of the excellent electrochemical performance of CuSe2 / (Cu,Co)Se2 composite material are: the synergistic effect generated by the unique heterojunction interface, the enriched defect structure and the optimized electron conduction, the two phases support each other and form a stable "mechanical skeleton", which effectively buffers the volume change during the charging and discharging process and prevents the electrode material from pulverizing; the heterojunction provides a fast electron channel.

[0135] Magnesium / sodium dual-ion batteries using different mixed electrolytes at 2.0 A g -1 Cyclic performance tests of coin cells were conducted at current densities of 0.1 A g. -1 0.3 A g -1 0.5 A g -1 1 A g -1 1.5 A g -1 2 A g -1 3 Ag -1 4 A g -1 5 A g -1 8 A g -1 10 A g -1 Rate performance was tested under varying current and at 4.0 A g. -1 The long-cycle performance under high current density in MACC / TGM-NaTFSI electrolyte, as shown in the results... Figure 22 , Figure 23 , Figure 24As shown, the magnesium / sodium dual-ion battery operates at 2.0 A g in MACC / TGM-NaTFSI electrolyte. -1 It has over 250 mAhg after 1000 cycles. -1 stable capacity ( Figure 22 The coulombic efficiency (CE) exceeds 99% in the range of 0.1–10.0 A g. -1 Cyclic testing was performed at current density, returning to 2.0 A g. -1 There is still more than 200 mAh g. -1 The high capacity of g demonstrates highly reversible rate performance. Figure 23 ). In 4.0 A g -1 Even after 7000 long cycles, it still has considerable capacity, and the coulombic efficiency remains at 99%, showing great application potential. Figure 24 This invention prepared a MACC / TGM-NaTFSI mixed ionic electrolyte by adding a modified NaTFSI solvent to a highly soluble MACC / TGM solution. The addition of NaTFSI improved the reaction kinetics at the electrode and electrolyte interface and improved the Mg... 2+ / Na + The rapid transport of ions extends the cycle life of magnesium / sodium hybrid ion batteries.

[0136] A magnesium / sodium hybrid ion battery, consisting of a CuSe2 / (Cu,Co)Se2 composite material as the cathode and MACC / TGM-NaTFSI electrolyte, also exhibits excellent electrochemical performance at high temperatures. The results are as follows... Figure 25 As shown, after 1000 cycles at 50 °C, the capacity exceeds 200 mAh g. -1 With a coulomb efficiency exceeding 99%, it demonstrates great potential for practical applications.

[0137] The above description of the embodiments is intended to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A method for preparing a nanostructured composite material, characterized in that, The preparation method includes the following steps: Cu2O / Co(OH)2 nanoflower material was dispersed in a solvent to obtain solution A; selenium powder was uniformly mixed in hydrazine hydrate solution to obtain solution B; solution B was added dropwise to solution A, ultrasonically dispersed, and then subjected to a solvothermal reaction to obtain nanosheet-like CuSe2 / (Cu,Co)Se2 nanoflower composite material.

2. The preparation method according to claim 1, characterized in that, In solution A, the ratio of Cu2O / Co(OH)2 nanoflower material to solvent is 0.0015-0.003 g / mL; the volume ratio of water to alcohol is 1-3:1-2.

3. The preparation method according to claim 1, characterized in that, The preparation method of the Cu2O / Co(OH)2 nanoflower material includes the following steps: 1) After mixing copper salt solution, sodium citrate solution, sodium carbonate solution and glucose solution, dilute with water, age, wash and dry, Cu2O nanoflower precursor is prepared. 2) Dissolve polyvinylpyrrolidone (PVP) in a mixed solution of ethanol and water, add Cu2O nanoflower precursor and cobalt salt to react, and then add sodium thiosulfate solution dropwise until the solution changes color to obtain nanosheet Cu2O / Co(OH)2 nanoflower precursor material.

4. The preparation method according to claim 3, characterized in that, In step 1), the copper salt solution is a copper sulfate solution with a concentration of 0.66-0.70 mol / L; the sodium citrate solution has a concentration of 0.72-0.76 mol / L; the sodium carbonate solution has a concentration of 1.0-1.4 mol / L; and the glucose solution has a concentration of 0.8-1.2 mol / L.

5. The preparation method according to claim 3, characterized in that, In step 2), the concentration of the sodium thiosulfate solution is 0.8-1.2 mol / L.

6. The preparation method according to claim 3, characterized in that, The mass ratio of selenium powder in solution B to Cu2O / Co(OH)2 nanoflower material in solution A is 1-3:1-2.

7. The preparation method according to claim 1, characterized in that, In the preparation method of the nanostructured composite material, the hydrothermal reaction temperature is 160-200℃ and the reaction time is 10-14 h.

8. A nanostructured composite material prepared by the preparation method according to any one of claims 1-7, characterized in that, The prepared nanostructured composite material is a core-shell nanosheet CuSe2 / (Cu,Co)Se2 nanoflower composite material with the following morphology: a four-petal flower-shaped in-situ long sheet structure with a size of 1-2 μm and a sheet structure size of 50-100 nm.

9. An electrode, characterized in that, A magnesium / sodium hybrid ion battery cathode was prepared using the nanostructured composite material described in claim 8 as the active material.

10. A rechargeable battery, characterized in that, The rechargeable battery includes an electrode made of the nanostructured composite material as described in claim 9; the rechargeable battery also includes an ether-modified MACC / TGM-NaTFSI electrolyte.

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