A ceria / carbon nanosphere composite material, a preparation method and application thereof

Abstract

The application provides a cerium dioxide / carbon nanosphere composite material and a preparation method and application thereof, and comprises carbon nanospheres and quantum dot cerium dioxide loaded on the inner and outer surfaces of the carbon nanospheres; the particle size of the carbon nanospheres is 0.8-1.2 mu m, and the carbon nanospheres are formed by stacking a plurality of hollow porous micro carbon nanospheres with a particle size of 150-250 nm; the particle size of the cerium dioxide is 2-5 nm; the carbon nanosphere substrate has a multi-cavity structure and can be used as a positive and negative electrode material of a sodium tellurium battery. The high catalytic activity and physical and chemical adsorption characteristics of the cerium dioxide quantum dots can accelerate the conversion of the positive electrode telluride and relieve the shuttle effect; the cerium dioxide quantum dots have excellent sodium affinity, can make sodium uniformly deposit, and inhibit dendrite growth. High-loading-capacity tellurium / cerium dioxide / carbon composite positive electrode materials and dendrite-free sodium / cerium dioxide / carbon composite negative electrode materials can be obtained, and a sodium tellurium battery with excellent performance is obtained.

Description

Technical Field

[0001] This application relates to a cerium dioxide / carbon nanosphere composite material, its preparation method and application, belonging to the field of energy storage materials. Background Technology

[0002] With the rapid development of new energy vehicles and portable electronics, the scarcity of lithium resources has become increasingly prominent. Sodium-ion batteries, due to the abundance of sodium resources, low cost, and similar physicochemical properties to lithium, have better application prospects in the field of large-scale energy storage. However, traditional sodium-ion batteries use cathode materials with embedded reaction mechanisms, resulting in very limited output energy density. Therefore, developing novel sodium-based secondary battery systems with low cost and high energy density has become a key research focus for the development of large-scale energy storage in today's society.

[0003] Sodium-tellurium batteries are an ideal candidate for achieving low-cost, high-specific-energy storage systems. Room-temperature sodium-tellurium batteries use metallic sodium and tellurium as the negative and positive electrodes, respectively. The theoretical specific capacity of the tellurium positive electrode is as high as 420 mAh / g, higher than that of traditional transition metal oxide positive electrodes (<200 mAh / g), enabling the achievement of high specific energy. Furthermore, tellurium, as a semiconductor material, possesses high electrical conductivity (2 × 10⁻⁶). 2 S / m), a value far higher than that of sulfur (1×10). -16 S / m) and selenium (10 -3 The positive electrode (S / m) greatly promotes the effective conduction of charge. However, studies have found that sodium tellurium batteries still face some key challenges, such as: (1) at the tellurium positive electrode, soluble polytellurides (Na2Te) are formed during the electrochemical reaction. n (1) It is easy to diffuse to the surface of the negative electrode metal sodium, severely corroding the negative electrode and causing the loss of positive electrode active material; (2) At the negative electrode of metal sodium, the continuous growth of sodium dendrites will not only reduce the battery cycle life, but may even puncture the separator and cause the battery to short circuit and cause a fire; (3) The positive and negative electrodes are prone to large volume changes during the cycle, resulting in severe pulverization of the electrodes, forming "dead sodium" and "dead tellurium", which further accelerates the decay of the capacitance.

[0004] For tellurium cathodes, combining tellurium with porous hollow carbon materials is an effective approach. Porous hollow carbon materials, acting as host materials, not only increase the contact area between tellurium and conductive carbon but also, through their physical confinement effect, limit the overflow and shuttle effect of polysulfides to some extent. However, the adsorption of polytellurides by carbon materials themselves is relatively weak, limiting the effectiveness of this confinement effect. For sodium anodes, combining three-dimensional framework carbon materials with sodium metal using a porous structure can effectively buffer volume changes during sodium metal anode cycling, ensuring electrode integrity. However, carbon-based materials themselves are not conducive to the uniform deposition of metallic sodium and easily induce dendrite formation. Summary of the Invention

[0005] In sodium-tellurium batteries, studies have shown that modifying carbon materials with polar, highly efficient catalysts can introduce abundant chemisorption sites, enhancing the adsorption of multiple tellurides. Simultaneously, the catalyst material can act as a catalytic active center, promoting the redox reaction between tellurium and sodium telluride, thus improving the utilization rate of the cathode material. For the sodium anode, introducing sodium-affinity sites onto the surface of the three-dimensional framework carbon material enhances the sodium-affinity properties of the host material, reduces the resistance to sodium deposition, and increases nucleation sites, thereby achieving a dendrite-free sodium anode.

[0006] According to one aspect of this application, a three-dimensional multi-cavity hollow carbon nanosphere composite material modified with cerium dioxide quantum dots is proposed. This material serves as both a host material for loading metallic sodium and tellurium, acting as both the anode and cathode of a sodium-tellurium battery. The quantum dot-scale cerium dioxide not only exhibits highly efficient chemical and physical adsorption properties to achieve highly active tellurium loading and effectively suppress the shuttle effect, but also its excellent sodium affinity provides abundant nucleation sites for sodium metal deposition, resulting in uniform sodium deposition.

[0007] According to one aspect of this application, a cerium dioxide / carbon nanosphere composite material is provided, the composite material comprising a three-dimensional multi-cavity hollow carbon nanosphere and cerium dioxide loaded on the inner and outer surfaces of the three-dimensional multi-cavity hollow carbon nanosphere;

[0008] The three-dimensional multi-cavity hollow carbon nanospheres are formed by stacking multiple hollow and porous micro carbon nanospheres;

[0009] The particle size of the three-dimensional multi-cavity hollow carbon nanospheres is 0.8–1.2 μm; the upper limit of the particle size of the three-dimensional multi-cavity hollow carbon nanospheres is 1.2 μm, 1.1 μm, 1.0 μm, and 0.9 μm; the lower limit is 0.8 μm, 0.9 μm, 1.0 μm, and 1.1 μm.

[0010] The hollow porous micro carbon nanospheres have a particle size of 150–250 nm; the upper limit of the particle size of the hollow porous micro carbon nanospheres is 250 nm, 225 nm, 200 nm, and 175 nm; the lower limit is 150 nm, 175 nm, 200 nm, and 225 nm.

[0011] The cerium dioxide is in the form of quantum dots with a particle size of 2–5 nm, with an upper limit of 5 nm, 4 nm, and 3 nm, and a lower limit of 2 nm, 3 nm, and 4 nm.

[0012] In the composite material, the content of cerium dioxide is 10-20 wt%, with an upper limit of 20 wt%, 19 wt%, 18 wt%, 17 wt%, 16 wt%, 15 wt%, 14 wt%, 13 wt%, 12 wt%, and 11 wt%, and a lower limit of 10 wt%, 11 wt%, 12 wt%, 13 wt%, 14 wt%, 15 wt%, 16 wt%, 17 wt%, 18 wt%, and 19 wt%.

[0013] Both the three-dimensional multi-cavity hollow carbon nanospheres and the hollow porous micro carbon nanospheres contain macropores, mesopores, and micropores.

[0014] The specific surface area of ​​the composite material is 600–900 m². 2 / g, the upper limit of the specific surface area of ​​the composite material is 900m². 2 / g、800m 2 / g、700m 2 / g; lower limit is 600m 2 / g、700m 2 / g、800m 2 / g.

[0015] According to another aspect of this application, a method for preparing the above-mentioned cerium dioxide / carbon nanosphere composite material is provided. The method involves preparing carbon nanospheres with a three-dimensional hierarchical multi-cavity hollow structure using silica nanospheres as templates, and then uniformly growing cerium dioxide quantum dots on the surface of the nanospheres through a hydrothermal reaction to obtain the cerium dioxide quantum dot / carbon nanosphere composite material.

[0016] At least the following steps are included:

[0017] (1) The raw material containing polymer monomers and silica nanospheres is mixed with solvent I, reacted, calcined, and etched with alkali to obtain precursor A;

[0018] (2) The material containing cerium salt, ammonia source and precursor A obtained in (1) is mixed with solvent II and reacted to obtain the cerium dioxide / carbon nanosphere composite material.

[0019] The polymer monomer is selected from at least one of resorcinol, dopamine hydrochloride, 4,4'-dihydroxydiphenyl sulfone, hexachlorotriphosphazene, melamine, or formaldehyde.

[0020] The ratio of the polymer monomer to the silica nanospheres is 0.5 to 3:1; the ratio of the polymer monomer to the silica nanospheres is selected from 0.5:1, 1:1, 1.5:1, 2:1, 2.5:1, and 3:1.

[0021] Solvent I is selected from at least one of methanol, ethanol, n-propanol, isopropanol, and ethylene glycol;

[0022] The concentration of the silica nanospheres in solvent I is 10–30 mg / mL; the upper limit of the concentration of the silica nanospheres in solvent I is 30 mg / mL, 25 mg / mL, 20 mg / mL, and 15 mg / mL; the lower limit is 10 mg / mL, 15 mg / mL, 20 mg / mL, and 25 mg / mL.

[0023] The temperature of reaction I is 15–35°C;

[0024] The reaction time for reaction I is 2–20 h;

[0025] The calcination temperature is 600–900°C;

[0026] The calcination time is 1 to 4 hours;

[0027] The alkali used in the alkaline etching is selected from an aqueous solution of sodium hydroxide with a concentration of 2-5 mol / L;

[0028] Optionally, the silica nanospheres are a solution of solvent I with a concentration of 10–30 mg / mL;

[0029] Optionally, the polymer monomer is a solution of solvent I with a concentration of 5-40 mg / mL.

[0030] The cerium salt is selected from at least one of cerium nitrate, cerium chloride, cerium sulfate, cerium oxalate, cerium acetate, or ammonium cerate.

[0031] The ammonia source is selected from at least one amino acid containing an amino group;

[0032] The ratio of the cerium salt to precursor A is 0.1 to 3:1;

[0033] Optionally, the ammonia source is selected from at least one of glycine, alanine, valine, leucine, isoleucine, methionine, tryptophan, serine, tyrosine, cysteine, phenylalanine, asparagine, glutamine, threonine, aspartic acid, glutamic acid, lysine, arginine, histidine, selenocysteine, or pyrrolidone.

[0034] The ratio of the ammonia source to precursor A is 1 to 10:1; the ratio of the ammonia source to precursor A is selected from 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, and 10:1.

[0035] Solvent II is selected from at least one of water, ethanol, methanol, ethanol, n-propanol, isopropanol, and ethylene glycol;

[0036] The concentration of precursor A in solvent II is 1–5 mg / mL, with the upper limit of the concentration of precursor A in solvent II being 5 mg / mL, 4 mg / mL, 3 mg / mL, and 2 mg / mL, and the lower limit being 1 mg / mL, 2 mg / mL, 3 mg / mL, and 4 mg / mL.

[0037] Reaction II is a hydrothermal reaction.

[0038] The temperature of reaction II is 60–100°C;

[0039] The reaction time for reaction II is 3 to 10 hours.

[0040] The silica nanospheres were obtained by the following method:

[0041] The silica nanospheres can be obtained by reacting a mixture containing tetraethyl orthosilicate, surfactant A, and an alkaline source in reaction IV.

[0042] The conditions for reaction IV are: temperature 35°C; time 0.5–4 h;

[0043] The alkaline source is selected from at least one of ammonia, sodium hydroxide, potassium hydroxide, lithium hydroxide, and calcium hydroxide;

[0044] The surfactant A is selected from cationic surfactants;

[0045] Optionally, the cationic surfactant is selected from at least one of polyvinylpyrrolidone, sodium dodecylbenzenesulfonate, hexadecyltrimethylammonium bromide, and polydiallyldimethylammonium chloride;

[0046] The material also includes solvent III;

[0047] Solvent III is selected from organic solutions, such as at least one of alcohols, N,N-dimethylformamide, n-hexane, cyclohexane, octadeceneamine, oleic acid, and oleylamine;

[0048] According to another aspect of this application, a tellurium / cerium dioxide / carbon composite material is provided, the tellurium / cerium dioxide / carbon composite material comprising a carrier I and amorphous tellurium distributed on the inner surface of the carrier;

[0049] The carrier I is selected from the above-mentioned cerium dioxide / carbon nanosphere composite material or the cerium dioxide / carbon nanosphere composite material prepared by the above-mentioned preparation method.

[0050] In the tellurium / cerium dioxide / carbon composite material, the mass content of tellurium is 50-70 wt%.

[0051] According to another aspect of this application, a method for preparing the above-mentioned tellurium / cerium dioxide / carbon composite material is provided, comprising at least the following steps:

[0052] The raw materials containing carrier I and tellurium source are mixed and reacted in reaction III to obtain the tellurium / cerium dioxide / carbon composite material.

[0053] The tellurium source is selected from elemental tellurium powder;

[0054] The mass ratio of the carrier I to the tellurium source is 1:1 to 1:5;

[0055] The temperature of reaction III is 420–480°C;

[0056] The reaction time for reaction III is 15–30 h;

[0057] The atmosphere for reaction III is an inert gas atmosphere;

[0058] The inactive gas is selected from nitrogen, argon or helium.

[0059] Reaction III is a melt diffusion process;

[0060] The melting diffusion is achieved by heating to 400-450°C at a rate of 1°C / min to 5°C / min and holding at that temperature for 10-15 hours.

[0061] Optionally, the heating rate is 2℃ / min.

[0062] According to another aspect of this application, a sodium / cerium dioxide / carbon composite material is provided, the sodium / cerium dioxide / carbon composite material comprising a carrier II and metallic sodium electrodeposited on the outer surface of the carrier II.

[0063] The metallic sodium is uniformly deposited on the outer surface of the carrier II.

[0064] The electrodeposition current density is 0.25 mA / cm². 2 The cutoff voltage is 0.5V.

[0065] The electrodeposition time is 8–32 hours.

[0066] According to another aspect of this application, a sodium tellurium battery is provided, wherein the positive electrode material of the sodium tellurium battery is selected from the tellurium / cerium dioxide / carbon composite material described above or the tellurium / cerium dioxide / carbon composite material prepared by the above preparation method.

[0067] The negative electrode material of the sodium tellurium battery is selected from the sodium / cerium dioxide / carbon composite material mentioned above.

[0068] The advantages of this application are:

[0069] 1. The carbon material is modified by using cerium dioxide, a polar and highly efficient catalytic material, which introduces abundant chemical adsorption sites to enhance the adsorption of multiple tellurides. At the same time, cerium dioxide can act as a catalytic active center to promote the redox reaction between telluride and sodium telluride, thereby improving the utilization rate of the cathode material.

[0070] 2. Introducing sodium-affinity sites on the surface of three-dimensional framework carbon materials enhances the sodium-affinity properties of the host material, reduces the resistance to sodium deposition, increases nucleation sites, and enables uniform sodium deposition, thus avoiding the formation of negative electrode dendrites.

[0071] 3. The sodium tellurium battery using the electrode material described in this application, at a current density of 0.1 A / g, exhibits an initial discharge specific capacity of 377.7 mAh / g and an initial coulombic efficiency of 57.9%. After 200 deep charge-discharge cycles, the discharge specific capacity of this material stabilizes at 218.6 mAh / g, with a coulombic efficiency of 97%, demonstrating good cycle stability. At a current density of 0.2C, after 10 charge-discharge cycles, its charge-discharge specific capacity is 392 mAh / g. As the current density gradually increases, the specific capacity decays slowly; even when the current density is increased to 20C, the battery can still release a specific capacity of 240 mAh / g. When the current density is adjusted back to 0.2C and the operation continues, its charge-discharge specific capacity is comparable to the initial specific capacity, and the capacity tends to stabilize in the following operation; at a current density of 10C, after 1000 constant current charge-discharge cycles, the reversible specific capacity can be maintained at 260mAh / g, the reversible capacity retention rate is as high as 93.8%, and the coulombic efficiency is close to 100%. Attached Figure Description

[0072] Figure 1 The images shown are field emission scanning electron microscope (SEM) images a and transmission electron microscope (TEM) images b, c, and d of the cerium dioxide / carbon nanosphere composite material prepared in Example 1.

[0073] Figure 2 These are field emission scanning electron microscope (SEM) images a and transmission electron microscope (TEM) images b, c, and d of the cerium dioxide / carbon nanosphere composite material.

[0074] Figure 3 The scanning electron microscope (SEM) image a and transmission electron microscope (TEM) image b of the tellurium / cerium dioxide / carbon nanosphere composite material obtained in Example 2 are shown. Figure 3 These are scanning electron microscope images c and d of the sodium / cerium dioxide / carbon nanospheres obtained in Example 3.

[0075] Figure 4 The X-ray diffraction patterns are those of cerium dioxide / carbon nanospheres obtained in Preparation Example 1, tellurium / cerium dioxide / carbon nanospheres obtained in Preparation Example 2, and pure tellurium.

[0076] Figure 5The thermogravimetric curve of the tellurium / cerium dioxide / carbon nanospheres obtained in Example 2 is shown.

[0077] Figure 6 The diagram shows the specific surface area (a) and pore size distribution (b) of the cerium dioxide / carbon nanospheres obtained in Preparation Example 1 and the tellurium / cerium dioxide / carbon nanosphere composites obtained in Preparation Example 2.

[0078] Figure 7 This is a cycle performance diagram of the Na-Te battery prepared in this application, with a current density of 0.2C.

[0079] Figure 8 This is a graph showing the rate performance of the Na-Te battery prepared in this application.

[0080] Figure 9 This is a graph showing the long-cycle performance of the Na-Te battery prepared in this application, with a current density of 10C.

[0081] Figure 10 These are field emission scanning electron microscope images a and b of the three-dimensional multi-cavity hollow carbon nanospheres prepared in Example 4.

[0082] Figure 11 These are field emission scanning electron microscope images a and b of the cerium dioxide / carbon nanospheres prepared in Example 5. Detailed Implementation

[0083] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.

[0084] Unless otherwise specified, all raw materials used in the embodiments of this application were purchased through commercial channels.

[0085] The present invention will be further described below with reference to the accompanying drawings and through embodiments. However, it should be noted that the embodiments do not constitute a limitation on the scope of protection of the present invention.

[0086] The instrument models used in this application embodiment are shown in Table 1 below:

[0087]

[0088]

[0089] Preparation Example 1

[0090] 1. Preparation of silica templates;

[0091] At 30°C, 3 ml of ammonia (25-28%) was added to a mixed solution of 10 ml of deionized water and 75 ml of ethanol, followed by 6 ml of tetraethyl orthosilicate. After stirring for 5 h, the mixture was centrifuged and dried to obtain silica nanospheres.

[0092] 2. Preparation of precursors;

[0093] 400 mg of the silica nanospheres prepared above were dissolved in 80 ml of methanol, referred to as solution A; 560 mg of hexachlorocyanuric acid and 1260 mg of 4,4-dihydroxydiphenyl sulfone were dissolved in 40 ml of methanol, referred to as solution B. Then, under vigorous stirring, solution B was added dropwise to solution A at a rate of 1 mL / min, and stirring continued for 6 hours. After the reaction was completed, the product was centrifuged and dried to obtain a white solid powder.

[0094] 3. Calcination process;

[0095] The white solid powder precursor obtained in step 2 was placed in a tube furnace filled with argon atmosphere and heated to 900℃ at a heating rate of 2℃ / min. The temperature was maintained for 2 hours, and after the reaction was complete, it was naturally cooled to room temperature to obtain a black solid powder. The above black solid powder was dissolved in NaOH aqueous solution (solution of 3M), stirred for 5 hours, and then centrifuged and dried to obtain three-dimensional multi-cavity hollow carbon nanospheres.

[0096] 4. Preparation of cerium dioxide / carbon nanosphere composite materials;

[0097] The three-dimensional multi-cavity hollow carbon nanospheres (100 mg) obtained in step 3 were placed in a 250 mL round-bottom flask with 100 mL of deionized water and stirred at 90 °C for 30 min. Subsequently, 50 mg of cerium nitrate, 4 mL of 6-aminoacetic acid, and 20 μL of concentrated hydrochloric acid were added to the above solution sequentially, and stirring was continued at the same temperature for 5 h. After the reaction was completed, the product was centrifuged and dried to obtain the cerium dioxide / carbon nanosphere composite material.

[0098] The sample obtained in Preparation Example 1 was characterized.

[0099] The morphology and structure of the three-dimensional multi-cavity hollow carbon nanospheres and cerium dioxide / carbon nanosphere composite materials prepared in Example 1 were observed using scanning electron microscopy and transmission electron microscopy. Figure 1 These are field emission scanning electron microscope (FEM) images a and b, and transmission electron microscope (TEM) images c and d, of three-dimensional multi-cavity hollow carbon nanospheres. Figure 1 As shown, Figure 1 As shown, the diameter of the three-dimensional multi-cavity hollow carbon nanospheres is approximately 1–1.3 μm. The three-dimensional multi-cavity hollow carbon nanospheres are composed of interconnected macroporous cages (i.e., micro carbon nanospheres) forming a multi-cavity spherical shape, while the outer wall of the carbon spheres has abundant mesopores / micropores. Figure 2 Images a and b, c, and d are field emission scanning electron microscope (FESEM) images of the cerium dioxide / carbon nanosphere composite material. It can be observed that the cerium dioxide / carbon nanosphere composite material retains the structural characteristics of porous carbon spheres, while cerium dioxide quantum dots are uniformly grown on the surface of the porous carbon spheres, with a particle size of 3–5 nm.

[0100] Preparation Example 2

[0101] Specific preparation process of tellurium / cerium dioxide / carbon nanosphere composite material

[0102] Cerium dioxide / carbon nanospheres and tellurium powder were uniformly mixed at a mass ratio of 1:2, sealed in a vacuum glass tube, placed in a tube furnace, and heated to 470℃ at a heating rate of 1.5℃ / min, and held at that temperature for 20h to obtain a tellurium / cerium dioxide / carbon nanosphere composite material.

[0103] The sample obtained in Preparation Example 2 was characterized.

[0104] Figure 3 The scanning electron microscope (SEM) image a and transmission electron microscope (TEM) image b of the tellurium / cerium dioxide / carbon nanosphere composite material obtained in Example 2 are shown. Figure 3 a and b indicate that in the tellurium / cerium dioxide / carbon nanosphere composite material, tellurium is well confined within the cavity of the cerium dioxide / carbon nanosphere composite material.

[0105] The material was subjected to X-ray powder diffraction testing, and its XRD pattern is shown below. Figure 4 As shown, in the cerium dioxide / carbon nanosphere composite material, distinct characteristic crystal plane reflection peaks (111), (200), (220), (311), and (222) are observed at positions of 28.5°, 33.1°, 47.4°, 56.3°, and 59.0°, which are characteristic peaks of CeO2 (JCPDS card number 34-0394). It is noteworthy that pure-phase tellurium exhibits a distinct and sharp peak shape, while the tellurium in the tellurium / cerium dioxide / carbon nanosphere composite material exhibits an amorphous state, indicating that tellurium is uniformly confined within the porous structure of the material.

[0106] like Figure 5 As shown, comprehensive thermal analysis tests revealed that the tellurium loading content in the tellurium / cerium dioxide / carbon nanosphere composite material was 63.7 wt%.

[0107] The specific surface area and pore size distribution of the prepared samples were analyzed using a specific surface area and porosity analyzer. Figure 6 a is a diagram showing the specific surface area and pore size distribution of the cerium dioxide / carbon nanospheres obtained in Preparation Example 1 and the tellurium / cerium dioxide / carbon nanosphere composites obtained in Preparation Example 2; as shown Figure 6 As shown in b, the specific surface area of ​​the cerium dioxide / carbon nanosphere composite material can reach 694.1 m². 2The material contains a uniform distribution of macropores, micropores, and mesopores. When tellurium is loaded onto the material, the specific surface area of ​​the tellurium / cerium dioxide / carbon nanosphere composite material decreases significantly compared to the cerium dioxide / carbon nanosphere composite material. This indicates that tellurium occupies the pore positions in the cerium dioxide / carbon nanosphere composite material, and the pore size distribution also shows a significant reduction, further demonstrating that tellurium is well confined within the cavity of the cerium dioxide / carbon nanospheres.

[0108] Preparation Example 3

[0109] Specific preparation process of sodium / cerium dioxide / carbon composite materials

[0110] Sodium / cerium dioxide / carbon composite materials were prepared by electrodeposition as follows: Sodium / cerium dioxide / carbon composite powder and binder (polyvinylidene fluoride PVDF) were uniformly ground at a mass ratio of 9:1, and a small amount of deionized water was added to form a slurry. This slurry was then coated onto copper foil using a scraper and kept in a vacuum drying oven at 80℃ for 24 hours. The dried electrode sheets were then cut into 12mm diameter pieces using a slicer. Finally, in a glove box, a coin cell was assembled using this material as the positive electrode, metallic sodium as the negative electrode, 1 mol NaPF6 as the electrolyte, and Celard 3501 as the separator. Sodium metal electrodeposition was then performed using a Wuhan LAND-CT2001 electrochemical workstation at an A / cm² depth of 0.25 mA / cm². 2 At a current density of 6 mAh / cm³, electrodeposition was performed over 24 hours, resulting in a deposition capacity of 6 mAh / cm³. 2 A sodium / cerium dioxide / carbon composite electrode was obtained.

[0111] The sample obtained in Preparation Example 3 was characterized.

[0112] Figure 3 These are scanning electron microscope images c and d of the sodium / cerium dioxide / carbon nanospheres obtained in Example 3. Figure 2 c and d are sodium / cerium dioxide / carbon nanosphere composite materials. From the morphology, metallic sodium is uniformly deposited on the surface of the host material.

[0113] Preparation Example 4

[0114] The preparation method of this embodiment is the same as step 2 of embodiment 1, except that the ratio of polymer monomers to silica nanospheres is adjusted to obtain three-dimensional multi-cavity hollow nanospheres of different sizes.

[0115] (1) When the ratio of polymer monomer to silica nanospheres is 0.5:1, its structure is as follows: Figure 10 As shown in a, the particle size of the three-dimensional multi-cavity hollow carbon nanospheres is about 500 nm, and the amount of internal cavities is relatively small.

[0116] (2) When the ratio of polymer monomer to silica nanospheres is 3:1, its morphology and structure are as follows: Figure 10 As shown in b, the particle size of the three-dimensional multi-cavity hollow carbon nanospheres is about 1.4 μm, and they have a large number of cavities inside.

[0117] Preparation Example 5

[0118] The preparation method in this embodiment is the same as step 4 of embodiment 1, except that the ratio of cerium salt to precursor A is adjusted.

[0119] (1) When the ratio of polymer monomer to silica nanospheres is 2:1, its structure is as follows: Figure 11 As shown in Figure a, the number of cerium dioxide nanoparticles on the surface of the porous carbon spheres increases, and their particle size increases to about 30-50 nm.

[0120] (2) When the ratio of polymer monomer to silica nanospheres is 3:1, its morphology and structure are as follows: Figure 11 As shown in b, cerium dioxide nanoparticles are densely distributed on the surface of porous carbon spheres, with a particle size of approximately 30–50 nm.

[0121] Example 1

[0122] 1) Preparation of positive electrode sheet: The tellurium / cerium dioxide / carbon nanosphere composite material obtained in preparation example 2, the conductive agent (Super P), and the binder (carboxymethyl cellulose CMC) were ground evenly in a mass ratio of 8:1:1. 1 ml of deionized water was added to prepare a slurry. The slurry was coated onto aluminum foil using a coating applicator, and then kept at 120°C for 24 hours in a vacuum drying oven. The dried electrode sheet was then cut into 12 mm diameter sheets using a slicer to serve as the positive electrode sheet.

[0123] 2) Preparation of negative electrode sheet as in Example 3

[0124] 3) The electrolyte solute is 1 mol / L sodium hexafluorophosphate, and the solvent is a mixed solvent of ethylene carbonate (EC), ethyl methyl carbonate (EMC) and dimethyl carbonate (DMC) in a volume ratio of 1:1:1.

[0125] 4) In the glove box, the prepared negative electrode material, positive electrode material, electrolyte, glass fiber separator, and positive and negative electrode battery shells are assembled in a certain order, and finally the Na-Te battery is completed by encapsulation.

[0126] Cycle performance tests were conducted on the prepared button-type sodium-based dual-ion battery. Figure 7The figure shows the electrochemical cycling performance of the prepared electrode material. As can be seen, at a current density of 0.5C (0.21 A / g), the initial discharge specific capacity and coulombic efficiency are 377.7 mAh / g and 57.9%, respectively. After 200 deep charge-discharge cycles, the discharge specific capacity stabilizes at 218.6 mAh / g, and the coulombic efficiency is 97%, demonstrating good cycle stability. The low coulombic efficiency in the first cycle is attributed to the formation of a solid electrolyte interphase (SEI) film, causing irreversible capacity loss. With continued charge-discharge cycles, the SEI film stabilizes, and the coulombic efficiency continuously increases.

[0127] The battery was then subjected to electrochemical performance testing. Figure 8 The graph shows the rate performance of the prepared Na-Te full cell. After 10 charge-discharge cycles at a current density of 0.2C, its charge-discharge specific capacity is 392 mAh / g. As the current density gradually increases, the specific capacity decays slowly; even when the current density is increased to 20C, the battery can still release a specific capacity of 240 mAh / g. When the current density is adjusted back to 0.2C and operation continues, its charge-discharge specific capacity is comparable to the initial specific capacity, and the capacity tends to stabilize in subsequent operations.

[0128] Figure 9 This is a long-cycle performance graph. It can be seen that at a current density of 10C, after 1000 constant-current charge-discharge cycles, the reversible specific capacity of this Na-Te full cell can be maintained at 260 mAh / g, with a reversible capacity retention rate as high as 93.8%, and a coulombic efficiency close to 100%. This demonstrates that the cerium dioxide / carbon nanosphere composite material effectively solves the shuttle effect of polysulfides in the tellurium cathode and the dendrite growth problem in the sodium anode.

[0129] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A cerium dioxide / carbon nanosphere composite material, characterized in that, The composite material comprises three-dimensional multi-cavity hollow carbon nanospheres and cerium dioxide loaded on the inner and outer surfaces of the three-dimensional multi-cavity hollow carbon nanospheres; the cerium dioxide is quantum dots with a particle size of 2~5nm; the content of cerium dioxide in the composite material is 10~20wt% of the composite material; the three-dimensional multi-cavity hollow carbon nanospheres are formed by stacking multiple hollow porous micro carbon nanospheres. The particle size of the three-dimensional multi-cavity hollow carbon nanospheres is 0.8~1.2μm; The hollow porous micro carbon nanospheres have a particle size of 150~250nm; Both the three-dimensional multi-cavity hollow carbon nanospheres and the hollow porous micro carbon nanospheres contain macropores, mesopores, and micropores. The specific surface area of ​​the composite material is 600~900m². 2 / g.

2. The cerium dioxide / carbon nanosphere composite material according to claim 1, characterized in that, The cerium dioxide is a quantum dot with a particle size of 3-4 nm; the content of the cerium dioxide in the composite material is 12-16 wt%.

3. The method for preparing the cerium dioxide / carbon nanosphere composite material according to any one of claims 1 to 2, characterized in that, At least the following steps are included: (1) Mix raw materials containing solvent I, polymer monomers and silica nanospheres, react I, calcine, and etch with alkali to obtain precursor A; (2) The material containing cerium salt, ammonia source and precursor A obtained in (1) is mixed with solvent II and reacted to obtain the cerium dioxide / carbon nanosphere composite material. The polymer monomer is selected from at least one of resorcinol and hexachlorotriphosphazene; The ratio of the polymer monomer to the silica nanospheres is 0.5~3:1; The temperature of reaction I is 15~35℃; The reaction time for reaction I is 2-20 hours; The calcination temperature is 600~900℃; The calcination time is 1 to 4 hours.

4. The production method according to claim 3, characterized by, Solvent I is selected from at least one of methanol, ethanol, n-propanol, isopropanol, and ethylene glycol.

5. The preparation method according to claim 3, characterized in that, The concentration of silica nanospheres in solvent I is 10~30 mg / mL.

6. The preparation method according to claim 3, characterized in that, The alkali used in the alkaline etching is selected from sodium hydroxide solution with a concentration of 2~5 mol / L.

7. The preparation method according to claim 3, characterized in that, The alkaline etching time is 3~10 hours.

8. The preparation method according to claim 3, characterized in that, The cerium salt is selected from at least one of cerium nitrate, cerium chloride, cerium sulfate, cerium oxalate, cerium acetate, or ammonium cerate. The ammonia source is selected from at least one amino acid containing an amino group.

9. The preparation method according to claim 3, characterized in that, The ratio of the cerium salt to precursor A is 0.1 to 3:

1.

10. The method of claim 3, wherein, The ammonia source is selected from at least one of glycine, alanine, valine, leucine, isoleucine, methionine, tryptophan, serine, tyrosine, cysteine, phenylalanine, asparagine, glutamine, threonine, aspartic acid, glutamic acid, lysine, arginine, histidine, selenocysteine, or pyrrolidone.

11. The preparation method according to claim 3, characterized in that, The ratio of the ammonia source to precursor A is 1 to 10:

1.

12. The method of claim 3, wherein, Solvent II is selected from at least one of water, ethanol, methanol, ethanol, n-propanol, isopropanol, and ethylene glycol.

13. The preparation method according to claim 3, characterized in that, The concentration of precursor A in solvent II is 1~5 mg / mL.

14. The preparation method according to claim 3, characterized in that, The temperature of reaction II is 60~100℃.

15. The preparation method according to claim 3, characterized in that, The reaction time for reaction II is 3 to 10 hours.

16. A tellurium / cerium dioxide / carbon composite material, characterized in that, The tellurium / cerium dioxide / carbon composite material includes a carrier I and amorphous tellurium distributed on the inner surface of the carrier; The carrier I is selected from the cerium dioxide / carbon nanosphere composite material according to claims 1-2 or the cerium dioxide / carbon nanosphere composite material prepared by the preparation method according to any one of claims 3-15; In the tellurium / cerium dioxide / carbon composite material, the mass content of tellurium is 50~70wt%.

17. The method for preparing the tellurium / cerium dioxide / carbon composite material according to claim 16, characterized in that, At least the following steps are included: The raw materials containing carrier I and tellurium source are mixed and reacted in reaction III to obtain the tellurium / cerium dioxide / carbon composite material.

18. The preparation method according to claim 17, characterized in that, The tellurium source is selected from elemental tellurium powder.

19. The preparation method according to claim 17, characterized in that, The mass ratio of the carrier I to the tellurium source is 1:1 to 1:

5.

20. The method of claim 17, wherein, The temperature of reaction III is 420~480℃.

21. The method of claim 17, wherein, The reaction time for reaction III is 15-30 hours.

22. The preparation method according to claim 17, characterized in that, The atmosphere for reaction III is an inert gas atmosphere.

23. The preparation method according to claim 22, characterized in that, The inactive gas is selected from nitrogen, argon or helium.

24. A sodium / cerium dioxide / carbon composite material, characterized in that, The sodium / cerium dioxide / carbon composite material includes a carrier II and metallic sodium deposited on the outer surface of the carrier II; The carrier II is selected from the cerium dioxide / carbon nanosphere composite material according to claims 1-2 or the cerium dioxide / carbon nanosphere composite material prepared by the preparation method according to any one of claims 3-15.

25. A sodium tellurium battery, characterized in that, The positive electrode material of the sodium tellurium battery is selected from the tellurium / cerium dioxide / carbon composite material of claim 16 or the tellurium / cerium dioxide / carbon composite material prepared by the preparation method of claims 17 to 23. The negative electrode material of the sodium tellurium battery is selected from the sodium / cerium dioxide / carbon composite material described in claim 24.

Images