Preparation method of Ti < 4 + >-doped sodium manganate material and application of Ti < 4 + >-doped sodium manganate material in sodium ion battery

Abstract

The invention discloses a preparation method of a Ti < 4 + >-doped sodium manganate material and application of the Ti < 4 + >-doped sodium manganate material in a sodium ion battery, and provides an improved strategy of titanium doping through a high-temperature solid-phase reaction, and the improved strategy changes the electronic structure and morphology of the material at the same time. Due to the addition of Ti < 4 + >, the interlayer spacing is increased, rapid diffusion of sodium ions is promoted, the structural evolution from a two-dimensional (2D) flat plate to a one-dimensional (1D) nanorod is also caused, and an additional sodium ion storage position is created. The electrochemical performance of the Na0. 7MnO2.05 positive electrode material is jointly improved through the synergistic effect of electronic modulation, Ti < 4 + > doping and nanostructure engineering. The preparation method is simple, raw materials are easy to obtain, and the process is simple. Tests show that a battery using the doped modified positive electrode material has a good capacity retention rate, and the sodium ion battery positive electrode material has excellent structural stability and cycle performance, so that the actual service life of the sodium ion battery is effectively prolonged.

Description

Technical Field

[0001] This invention belongs to the field of manganese-based sodium electrochemical materials technology, specifically relating to a Ti 4+ Preparation method of sodium manganate-doped materials and their application in sodium-ion batteries. Background Technology

[0002] The global energy structure is rapidly transitioning towards a cleaner and lower-carbon model, requiring breakthroughs in key material technologies for new energy storage batteries and the development of high-performance, long-life sodium-ion batteries. Among these, P2-Na... x MnO2 cathode material, as a candidate material for sodium-ion batteries, has advantages such as low cost and environmental friendliness, but its technical defects significantly restrict its practical application. According to existing research, its three core defects are as follows: (1) Irreversible phase transitions during charging and discharging lead to structural degradation; (2) Mn 3+ The disproportionation reaction and Jahn-Teller effect lead to capacity loss; (3) the "defect phase behavior" of the first charge and discharge cycle leads to low voltage and capacity loss. In order to improve the above defects, relevant R&D personnel have done a lot of work. For example, the team of Zhang Genqiang at the University of Science and Technology of China found through in-situ XRD that unmodified P2-Na x MnO2 cathode materials exhibit a P2-O2 phase transition during the initial charge-discharge cycle. However, by modulating the phase transition through oxygen anion redox reactions, the modified cathode material achieved phase transition-free cycling, significantly improving structural stability. Professor Jongsoon Kim's team at Sejong University in South Korea suppressed the P2-OP4 phase transition through titanium doping, enabling the cathode material to retain 86% of its capacity after 200 cycles, while the undoped cathode material experienced rapid capacity decay. A team at Xiamen University discovered that Mn... 3+ Disproportionation is one of the main causes of capacity decay in P2-type manganese-based base oxides, and cobalt doping can reduce its content and improve stability. The Zhao Yufeng research group at Shanghai University suppressed Mn disproportionation through trace La doping and surface modification. 3+ The disproportionation reaction resulted in a 70% capacity retention rate for the cathode material after 300 cycles. A team led by Hu Yongsheng at the Chinese Academy of Sciences discovered that high-sodium-content P2-type materials can suppress the P2-O2 phase transition, improving first-cycle efficiency and cycle stability.

[0003] Patent document CN201810386973.1 discloses a method for preparing nano-doped sodium titanium manganate, comprising the following steps: weighing Mn2O3, Na2CO3, and TiO2, grinding them in a mortar until uniformly mixed, then pressing them into sheets in a mold; calcining the pressed sheets in a box furnace; grinding the calcined sample again in a mortar for 10–120 minutes to ensure the powder is fully homogeneous, then ball milling it; cooling to room temperature after grinding, and cleaning to obtain the product. This patent uses a conventional calcination method to prepare nano-doped sodium titanium manganate, which cannot effectively guarantee the quality of TiO2.4+ Doping cannot achieve Ti 4+ Doped P2-Na 0.7 MnO 2.05 The morphological transformation of cathode materials from two-dimensional (2D) plates to one-dimensional (1D) nanorods.

[0004] Patent document CN202310885268.7 discloses a method for preparing a Ti-ion-doped modified sodium manganate aqueous sodium battery. The method involves mixing sodium salt, manganese salt, and titanium precursor, followed by high-energy ball milling to obtain precursor mixture A. Precursor mixture A is then sintered at high temperature in an air or oxygen atmosphere, followed by washing and drying to obtain the active component oxide Na2Mn3Ti. x O7; Using titanium foil or stainless steel mesh as the substrate, active ingredient oxides are coated or pressed onto the substrate to prepare a Ti ion-doped modified sodium manganate positive electrode sheet; using sodium salt aqueous solution as the electrolyte, zinc sheet or hard carbon as the negative electrode, and Ti ion-doped modified sodium manganate positive electrode sheet as the positive electrode, an aqueous sodium ion Na2Mn3Ti system is assembled. x O7 battery. This patent uses conventional processes to prepare nano-doped sodium titanate manganese oxide, which cannot effectively guarantee the quality of Ti. 4+ Doping cannot achieve Ti 4+ Doped P2-Na 0.7 MnO 2.05 The morphological transformation of cathode materials from two-dimensional (2D) plates to one-dimensional (1D) nanorods.

[0005] To address the aforementioned shortcomings, current research mainly focuses on the following improvement strategies: (1) Element doping: By introducing elements such as Ti, Zn, and La, the layered structure is stabilized and phase transitions are suppressed; (2) Surface modification: Carbon coating or perovskite modification is used to reduce side reactions between the electrolyte and active materials, thereby improving interface stability; (3) Anion redox regulation: Activating oxygen anions to participate in charge compensation, replacing some transition metal redox reactions, and reducing structural stress. These improvement strategies have significantly improved the performance of P2-Na x The cycle life and rate performance of MnO2 have laid the foundation for its commercial application. However, the aforementioned improvement strategies still need further enhancement and optimization. Summary of the Invention

[0006] The technical problem solved by this invention is to provide a Ti 4+ Preparation method of sodium manganate-doped material and its application in sodium-ion batteries. The method uses a simple experimental setup and synthesizes Ti using a high-temperature pure oxygen solid-state method. 4+ By doping sodium manganate, a sodium-ion battery electrode material with high specific energy and cycle stability was ultimately obtained. The Ti in this electrode material... 4+ Doping can affect P2-Na 0.7 MnO2.05 Interlayer modulation of the cathode material increases the distance between oxygen layers. Accelerate Na + Diffusion kinetics; and through careful optimization of material morphology, Ti 4+ Doped P2-Na 0.7 MnO 2.05 The cathode material has achieved a morphological transformation from two-dimensional (2D) plates to one-dimensional (1D) nanorods.

[0007] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: a Ti 4+ The preparation method for sodium manganate-doped materials, and its specific preparation steps are as follows:

[0008] Step S1: Weigh 0.4 mol MnSO4·H2O and dissolve it in 100 mL of deionized water to prepare solution A. Weigh 0.101 mol NaHCO3 and dissolve it in 100 mL of deionized water to prepare solution B. Add solution B to solution A and stir and mix evenly at room temperature to obtain a white suspension. After vacuum filtration, wash the suspension three times each with deionized water and anhydrous ethanol, transfer it to a glass dish, dry it at 80-90℃ for 8-12 h, and then grind it to obtain white spherical MnCO3 precursor powder.

[0009] Step S2: Weigh the raw materials according to the ratio of 7.21 mmol NaOH, 8 mmol MnCO3 precursor powder, and 2 mmol TiO2. Using deionized water as a solvent, grind the materials in an agate mortar under a heat lamp to form a slurry. Transfer the slurry to a petri dish and dry it at 80–90 °C for 8–12 hours. Remove the slurry, grind it into powder, place it in a porcelain boat, and then place it in a tube furnace purged with pure oxygen at 2–5 °C / min. -1 The temperature was increased to 700–900℃ at a heating rate and held for 3–6 hours to finally obtain the black cathode material Na. 0.7 Ti 0.2 Mn 0.8 O 2.05 ;

[0010] The positive electrode material Na 0.7 Ti 0.2 Mn 0.8 O 2.05 Ti 4+ Doping can affect P2-Na 0.7 MnO 2.05 Interlayer modulation of the cathode material increases the distance between oxygen layers. Accelerate Na + Diffusion kinetics; and through careful optimization of material morphology, Ti 4+ Doped P2-Na 0.7 MnO 2.05The cathode material achieves a morphological transformation from a two-dimensional (2D) plate to a one-dimensional (1D) nanorod, and the cathode material Na... 0.7 Ti 0.2 Mn 0.8 O 2.05 It has good electrochemical sodium storage capacity and cycle stability, and can be used to prepare sodium-ion battery electrodes.

[0011] The Ti of the present invention 4+ Sodium manganate-doped materials are used as cathode materials in the assembly of sodium-ion batteries. The specific process is as follows: Sodium manganate is used as a cathode material in sodium-ion batteries. 0.7 Ti 0.2 Mn 0.8 O 2.05 The conductive agent acetylene black and the binder polyvinylidene fluoride were mixed in a mass ratio of 8:1:1, with N-methylpyrrolidone as the solvent. The mixture was placed in an agate mortar and ground for 15 minutes under an infrared lamp to obtain a slurry. The slurry was manually coated onto a current collector aluminum foil, placed flat on tempered glass, and transferred to a vacuum drying oven at 110°C for 8 hours to dry, thus preparing an electrode sheet with a diameter of 10 mm. The electrode sheet was placed in a glove box filled with argon atmosphere with a water content and oxygen content of less than 0.1 ppm to reduce the moisture adsorbed during the transfer process. Then, the electrode sheet was assembled into a CR2032 coin cell in the glove box, using a 14 mm diameter circular commercial sodium sheet as the negative electrode, a 1 mol / L NaClO4 solution as the electrolyte, and a 16 mm diameter glass fiber membrane as the separator. The battery was aged for 8 hours after assembly.

[0012] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0013] (1) Ti prepared by the method of the present invention 4+ Sodium manganate-doped materials, with Ti 4+ With increasing doping concentration, P2-Na 0.7 MnO 2.05 The morphology changed from two-dimensional (2D) plates to one-dimensional (1D) nanorods. Furthermore, the prepared Ti... 4+ Sodium manganate-doped materials exhibit good electrochemical sodium storage capacity and cycle stability, and can be used to prepare sodium-ion battery electrodes, which is of great value for the research of sodium energy storage devices.

[0014] (2) The present invention successfully prepared Ti 4+ To achieve Ti by doping sodium manganate materials 4+ Effective doping. Ti 4+ After doping, it partially replaces manganese ions, Ti 4+ Priority entry into Na 0.7 MnO 2.05The lattice forms strong Ti-O-Mn bonds, which can regulate the occupancy state of Mn 3d electrons in the eg orbitals, effectively suppressing the Jahn-Teller distortion and harmful phase transition of Mn(III). 4+ Sodium manganate-doped materials have great potential and are expected to be used in sodium-ion secondary batteries for energy storage devices.

[0015] (3) The present invention has significant advantages, the process is simple and easy to operate, the experimental process is greatly shortened, the raw materials are easy to obtain and the cost is low, no toxic or harmful substances are generated in the entire preparation process, and the environmental protection is excellent; the overall conditions are mature, and it is very easy to move from the laboratory to large-scale industrial production. Attached Figure Description

[0016] Figure 1 A simplified diagram of the experimental setup for preparing cathode materials.

[0017] Figure 2 The XRD patterns of cathode materials prepared according to different raw material ratios are shown.

[0018] Figure 3 Raman spectra of cathode materials prepared with different raw material ratios.

[0019] Figure 4 The images shown are SEM and TEM images of the cathode material prepared in Example 1.

[0020] Figure 5 This is a long-cycle life test diagram of the cathode material prepared in Example 1. Detailed Implementation

[0021] The following examples further illustrate the above-described content of the present invention, but it should not be construed as limiting the scope of the subject matter of the present invention to the following examples. All technologies implemented based on the above-described content of the present invention fall within the scope of the present invention.

[0022] The following examples and comparative examples utilize experimental setups for preparing related materials using high-temperature solid-state reactions, such as... Figure 1 As shown.

[0023] Example 1

[0024] (1) Weigh 0.4 mol MnSO4·H2O and dissolve it in 100 mL of deionized water to prepare solution A. Weigh 0.101 mol NaHCO3 and dissolve it in 100 mL of deionized water to prepare solution B. Slowly add solution B to solution A and stir magnetically at room temperature for 3 h to obtain a white suspension. After vacuum filtration, wash the suspension three times with deionized water and three times with anhydrous ethanol, transfer it to a glass dish, dry it at 80 °C for 10 h, and then grind it to obtain white spherical MnCO3 precursor powder.

[0025] (2) Weigh the raw materials according to the ratio of 7.21 mmol (3% excess) NaOH, 8 mmol MnCO3 precursor powder and 2 mmol TiO2. Use deionized water as solvent and grind them in an agate mortar under a heat lamp for 15 min to form a slurry. Transfer the slurry to a petri dish and dry it at 80℃ for 10 h. Take it out, grind it into powder and place it in a porcelain boat. Then put it into a tube furnace with pure oxygen and heat it at 3℃·min. -1 The temperature was increased to 800℃ and held for 4 hours at a certain heating rate, finally yielding the black cathode material Na. 0.7 Ti 0.2 Mn 0.8 O 2.05 .

[0026] Comparative Example 1 (Undoped Ti) 4+ )

[0027] (1) Weigh 0.4 mol MnSO4·H2O and dissolve it in 100 mL of deionized water to prepare solution A. Weigh 0.101 mol NaHCO3 and dissolve it in 100 mL of deionized water to prepare solution B. Slowly add solution B to solution A and stir magnetically at room temperature for 3 h to obtain a white suspension. After vacuum filtration, wash the suspension three times with deionized water and three times with anhydrous ethanol, transfer it to a glass dish, dry it at 80 °C for 10 h, and then grind it to obtain white spherical MnCO3 precursor powder.

[0028] (2) Weigh the raw materials according to the ratio of 7.21 mmol (3% excess) NaOH and 10 mmol MnCO3 precursor powder. Using deionized water as solvent, grind the raw materials in an agate mortar under a heat lamp for 15 min to form a slurry. Transfer the slurry to a petri dish and dry it at 80℃ for 10 h. Remove the slurry, grind it into powder, place it in a porcelain boat, and then place it in a tube furnace with pure oxygen at 3℃·min. -1 The temperature was increased to 800℃ and held for 4 hours at a certain heating rate, finally yielding the black cathode material Na. 0.7 MnO 2.05 .

[0029] Comparative Example 2 (Adjusting the high-temperature solid-phase reaction atmosphere)

[0030] (1) Weigh 0.4 mol MnSO4·H2O and dissolve it in 100 mL of deionized water to prepare solution A. Weigh 0.101 mol NaHCO3 and dissolve it in 100 mL of deionized water to prepare solution B. Slowly add solution B to solution A and stir magnetically at room temperature for 3 h to obtain a white suspension. After vacuum filtration, wash the suspension three times with deionized water and three times with anhydrous ethanol, transfer it to a glass dish, dry it at 80 °C for 10 h, and then grind it to obtain white spherical MnCO3 precursor powder.

[0031] (2) Weigh the raw materials according to the ratio of 7.21 mmol (3% excess) NaOH, 8 mmol MnCO3 precursor powder and 2 mmol TiO2. Use deionized water as solvent and grind them in an agate mortar under a heat lamp for 15 min to form a slurry. Transfer the slurry to a petri dish and dry it at 80℃ for 10 h. Take it out, grind it into powder and place it in a porcelain boat. Then put it in a muffle furnace and heat it at 3℃·min. -1 The temperature was increased to 800℃ and held for 4 hours at a certain heating rate, finally yielding the black cathode material Na. 0.7 Ti 0.2 Mn 0.8 O 2.05 .

[0032] Comparative Example 3 (Adjusting the doping ratio)

[0033] (1) Weigh 0.4 mol MnSO4·H2O and dissolve it in 100 mL of deionized water to prepare solution A. Weigh 0.101 mol NaHCO3 and dissolve it in 100 mL of deionized water to prepare solution B. Slowly add solution B to solution A and stir magnetically at room temperature for 3 h to obtain a white suspension. After vacuum filtration, wash the suspension three times with deionized water and three times with anhydrous ethanol, transfer it to a glass dish, dry it at 80 °C for 10 h, and then grind it to obtain white spherical MnCO3 precursor powder.

[0034] (2) Weigh the raw materials according to the ratio of 7.21 mmol (3% excess) NaOH, 9.5 mmol MnCO3 precursor powder and 0.5 mmol TiO2. Use deionized water as solvent and grind them in an agate mortar under a heat lamp for 15 min to form a slurry. Transfer the slurry to a petri dish and dry it at 80℃ for 10 h. Take it out, grind it into powder and place it in a porcelain boat. Then put it into a tube furnace with pure oxygen and heat it at 3℃·min. -1 The temperature was increased to 800℃ and held for 4 hours at a certain heating rate, finally yielding the black cathode material Na. 0.7 Ti 0.05 Mn 0.95 O 2.05 .

[0035] Comparative Example 4 (Adjusting the doping ratio)

[0036] (1) Weigh 0.4 mol MnSO4·H2O and dissolve it in 100 mL of deionized water to prepare solution A. Weigh 0.101 mol NaHCO3 and dissolve it in 100 mL of deionized water to prepare solution B. Slowly add solution B to solution A and stir magnetically at room temperature for 3 h to obtain a white suspension. After vacuum filtration, wash the suspension three times with deionized water and three times with anhydrous ethanol, transfer it to a glass dish, dry it at 80 °C for 10 h, and then grind it to obtain white spherical MnCO3 precursor powder.

[0037] (2) Weigh the raw materials according to the ratio of 7.21 mmol (3% excess) NaOH, 9 mmol MnCO3 precursor powder and 1 mmol TiO2. Use deionized water as solvent and grind them in an agate mortar under a heat lamp for 15 min to form a slurry. Transfer the slurry to a petri dish and dry it at 80℃ for 10 h. Take it out, grind it into powder and place it in a porcelain boat. Then put it in a tube furnace with pure oxygen and heat it at 3℃·min. -1 The temperature was increased to 800℃ and held for 4 hours at a certain heating rate, finally yielding the black cathode material Na. 0.7 Ti 0.1 Mn 0.9 O 2.05 .

[0038] Comparative Example 5 (Adjusting the doping ratio)

[0039] (1) Weigh 0.4 mol MnSO4·H2O and dissolve it in 100 mL of deionized water to prepare solution A. Weigh 0.101 mol NaHCO3 and dissolve it in 100 mL of deionized water to prepare solution B. Slowly add solution B to solution A and stir magnetically at room temperature for 3 h to obtain a white suspension. After vacuum filtration, wash the suspension three times with deionized water and three times with anhydrous ethanol, transfer it to a glass dish, dry it at 80 °C for 10 h, and then grind it to obtain white spherical MnCO3 precursor powder.

[0040] (2) Weigh the raw materials according to the ratio of 7.21 mmol (3% excess) NaOH, 8.5 mmol MnCO3 precursor powder and 1.5 mmol TiO2. Use deionized water as solvent and grind them in an agate mortar under a heat lamp for 15 min to form a slurry. Transfer the slurry to a petri dish and dry it at 80℃ for 10 h. Take it out, grind it into powder and place it in a porcelain boat. Then put it into a tube furnace with pure oxygen and heat it at 3℃·min. -1 The temperature was increased to 800℃ and held for 4 hours at a certain heating rate, finally yielding the black cathode material Na. 0.7 Ti 0.15 Mn 0.85 O 2.05 .

[0041] Comparative Example 6 (Adjusting the doping ratio)

[0042] (1) Weigh 0.4 mol MnSO4·H2O and dissolve it in 100 mL of deionized water to prepare solution A. Weigh 0.101 mol NaHCO3 and dissolve it in 100 mL of deionized water to prepare solution B. Slowly add solution B to solution A and stir magnetically at room temperature for 3 h to obtain a white suspension. After vacuum filtration, wash the suspension three times with deionized water and three times with anhydrous ethanol, transfer it to a glass dish, dry it at 80 °C for 10 h, and then grind it to obtain white spherical MnCO3 precursor powder.

[0043] (2) Weigh the raw materials according to the ratio of 7.21 mmol (3% excess) NaOH, 7.5 mmol MnCO3 precursor powder and 2.5 mmol TiO2. Use deionized water as solvent and grind them in an agate mortar under a heat lamp for 15 min to form a slurry. Transfer the slurry to a petri dish and dry it at 80℃ for 10 h. Take it out, grind it into powder and place it in a porcelain boat. Then put it into a tube furnace with pure oxygen and heat it at 3℃·min. -1 The temperature was increased to 800℃ and held for 4 hours at a certain heating rate, finally yielding the black cathode material Na. 0.7 Ti 0.25 Mn 0.75 O 2.05 .

[0044] Battery assembly is completed using the following method:

[0045] The positive electrode materials obtained in Example 1 and Comparative Examples 1-6 were used as sodium electrode materials. They were mixed with conductive agent acetylene black (Super-p) and binder polyvinylidene fluoride (PVDF) in a mass ratio of 8:1:1, using N-methylpyrrolidone (NMP) as solvent. The mixture was placed in an agate mortar and ground for 15 minutes under an infrared lamp to obtain a slurry. The slurry was manually coated onto a current collector aluminum foil, placed flat on tempered glass, and transferred to a vacuum drying oven at 110°C for 8 hours to dry, preparing an electrode sheet with a diameter of 10 mm. This electrode was then placed in a glove box filled with argon atmosphere for 3 hours to reduce moisture adsorbed during transfer. Finally, it was assembled into a CR2032 coin cell in the glove box. A 14 mm diameter circular commercial sodium sheet was used as the negative electrode, a 1 mol / L NaClO4 solution as the electrolyte, and a 16 mm diameter glass fiber membrane as the separator. After assembly, the battery was aged for 8 hours.

[0046] The battery was tested at a voltage of 1.8–4V with a capacity of 100 mAg. -1 The discharge specific capacity after 100 cycles at the specified current density is shown in Table 1.

[0047] Table 1

[0048]

[0049] As can be seen from the performance comparison data of Example 1 and Comparative Example 2, Na 0.7 Mn 0.8 Ti 0.2 O 2.05 Sintering is performed in a tube furnace with pure oxygen (rather than a muffle furnace with an air atmosphere) because pure oxygen sintering allows Ti to... 4+Maintaining a high valence state, it preferentially enters the sodium manganate lattice to form strong TM-O-Mn bonds (Ti-O bond energy is approximately 672 kJ / mol, far exceeding the Mn-O bond energy of 402 kJ / mol), weakening the Na-O interaction and slightly increasing the interlayer spacing. Simultaneously, the high valence state Ti... 4+ Doping can control the occupancy state of Mn3d electrons in the eg orbitals, and pure oxygen sintering makes Mn 4+ It becomes the dominant valence state, effectively suppressing Mn 3+ JT distortion and harmful phase transitions.

[0050] Na was sintered in an air-atmosphere muffle furnace. 0.7 Mn 0.8 Ti 0.2 O 2.05 At this time, the number of vacancy defects in the material increases, and Ti entering the sodium manganate lattice may exhibit mixed valence states such as +2, +3, and +4. Although the increase in vacancy defects can increase the Na content during charging and discharging... + The amount of insertion / extraction, but due to numerous material defects and Mn 3+ The JT effect caused by this process leads to the collapse of the material's crystal structure after several cycles, resulting in poor electrochemical stability.

[0051] Based on the performance comparison data of Example 1 and Comparative Examples 3-6, Ti 4+ The reasons why doping level affects material properties are as follows:

[0052] On the one hand, Ti 4+ Low doping concentration leads to poor performance: small amount of Ti 4+ Doping allows Ti to enter the sodium manganate lattice 4+ As Ti decreases, the number of TM-O-Mn bonds decreases or even fails to form, leading to material structural instability. Although the Ti-O bond energy is greater than the Mn-O bond energy, which can weaken the interaction between Na and O, the reduction in Ti... 4+ With low doping levels, the number of Ti-O bonds formed is extremely small, which cannot effectively expand the interlayer spacing, resulting in poor material performance.

[0053] On the other hand, Ti 4+ Excessive doping leads to poor performance: TiO2 is an inactive substance. Excessive doping will cause TiO2 to precipitate on the material surface, reducing the amount of Na insertion / extraction during charging and discharging, thus affecting the material performance.

[0054] The above embodiments describe the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are only illustrative of the principles of the present invention. Various changes and modifications can be made to the present invention without departing from the scope of the principles of the present invention, and all such changes and modifications fall within the protection scope of the present invention.

Claims

1. A Ti 4+ The method for preparing sodium manganate-doped materials is characterized by: The specific preparation steps are as follows: Step S1: Weigh 0.4 mol MnSO4·H2O and dissolve it in 100 mL of deionized water to prepare solution A. Weigh 0.101 mol NaHCO3 and dissolve it in 100 mL of deionized water to prepare solution B. Add solution B to solution A and stir and mix evenly at room temperature to obtain a white suspension. After vacuum filtration, wash the suspension three times each with deionized water and anhydrous ethanol, transfer it to a glass dish, dry it at 80~90℃ for 8~12 h, and then grind it to obtain white spherical MnCO3 precursor powder. Step S2: Weigh the raw materials according to the ratio of 7.21 mmol NaOH, 8 mmol MnCO3 precursor powder, and 2 mmol TiO2. Using deionized water as a solvent, grind the materials in an agate mortar under a heat lamp to form a slurry. Transfer the slurry to a petri dish and dry it at 80-90℃ for 8-12 hours. Remove the slurry, grind it into powder, place it in a porcelain boat, and then place it in a tube furnace with pure oxygen. Heat the boat to 700-900℃ at a heating rate of 2-5℃·min⁻¹ and hold for 3-6 hours to finally obtain the black cathode material Na. 0.7 Ti 0.2 Mn 0.8 O 2.05 ; The positive electrode material Na 0.7 Ti 0.2 Mn 0.8 O 2.05 Ti 4+ Doping can affect P2-Na 0.7 MnO 2.05 Interlayer modulation of the cathode material increases the oxygen interlayer distance by 0.1 Å, accelerating the Na... + Diffusion kinetics; and through careful optimization of material morphology, Ti 4+ Doped P2-Na 0.7 MnO 2.05 The cathode material achieves a morphological transformation from a two-dimensional (2D) plate to a one-dimensional (1D) nanorod, and the cathode material Na... 0.7 Ti 0.2 Mn 0.8 O 2.05 It has good electrochemical sodium storage capacity and cycle stability, and can be used to prepare sodium-ion battery electrodes.

2. Ti prepared according to the method of claim 1 4+ Application of sodium manganate-doped materials as positive electrode materials in the assembly of sodium-ion batteries.

3. The application according to claim 2, characterized in that... The specific process is as follows: Na, the positive electrode material... 0.7 Ti 0.2 Mn 0.8 O 2.05 The conductive agent acetylene black and the binder polyvinylidene fluoride were mixed in a mass ratio of 8:1:1, with N-methylpyrrolidone as the solvent, and ground in an agate mortar for 15 minutes under an infrared lamp to obtain a slurry. The slurry was manually coated onto a current collector aluminum foil, placed flat on tempered glass, and transferred to a vacuum drying oven at 110°C for 8 hours to prepare an electrode sheet with a diameter of 10 mm. The electrode sheet was placed in a glove box filled with argon atmosphere with a water content and oxygen content of less than 0.1 ppm for 3 hours to reduce the moisture adsorbed during the transfer process. Then, it was assembled into a CR2032 coin cell in the glove box, using a 14 mm diameter circular commercial sodium sheet as the negative electrode, a 1 mol / L NaClO4 solution as the electrolyte, and a 16 mm diameter glass fiber membrane as the separator. After the battery was assembled, it was aged for 8 hours. The battery showed good electrochemical sodium storage capacity and cycle stability.

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