CN-121976325-A - High-voltage titanium manganese sodium phosphate and chromium manganese sodium phosphate positive electrode material nanofiber and preparation method thereof

CN121976325ACN 121976325 ACN121976325 ACN 121976325ACN-121976325-A

Abstract

The invention discloses a high-voltage titanium manganese sodium phosphate and chromium manganese sodium phosphate anode material nanofiber and a preparation method thereof, and belongs to the technical field of sodium ion batteries. The method adopts a phosphorus-containing chelating agent to replace the traditional phosphorus source, dissolves the phosphorus-containing chelating agent in an organic solvent, sequentially adds a manganese source, a sodium source, a titanium source or a chromium source and a high polymer, forms a uniform precursor solution through heating and stirring reaction, then prepares a nanofiber precursor through an electrostatic spinning technology, and finally obtains a target product through stepwise carbonization heat treatment. The invention solves the problems of indissolvable and uneven mixing of the traditional inorganic phosphorus source in the organic solvent by utilizing the dual functions of the phosphorus-containing chelating agent, realizes the molecular-level mixing of raw materials, and the prepared positive electrode material has a high-purity NASICON structure, uniform nanofiber morphology and an in-situ carbon coating network, and improves the charge-discharge specific capacity, high voltage stability and cycle life of the sodium ion battery. The process is simple and is suitable for large-scale production.

Inventors

WEI PENG
LV SHANSHAN
REN YURONG
LIANG KANG

Assignees

常州大学

Dates

Publication Date: 20260505
Application Date: 20260210

Claims (9)

1. The preparation method of the high-voltage titanium manganese sodium phosphate and chromium manganese sodium phosphate positive electrode material nanofiber is characterized by comprising the following steps of: Dissolving a phosphorus-containing chelating agent in an organic solvent, and stirring in a heating state, wherein the phosphorus-containing chelating agent is at least one selected from phytic acid or organic phosphonic acid; adding a manganese source and a sodium source into the solution in the first step, and continuously stirring until the manganese source and the sodium source are completely dissolved; adding a proper amount of titanium source or chromium source into the solution in the second step, and continuously stirring, wherein the heating state is kept in the process; step four, polyvinylpyrrolidone is added to obtain a titanium manganese sodium phosphate or chromium manganese sodium phosphate precursor solution, and the solution is reacted and stirred under the condition of heating and sealing to obtain a uniform spinning precursor solution; Step five, carrying out electrostatic spinning on the precursor solution obtained in the step four to obtain a titanium manganese sodium phosphate or chromium manganese sodium phosphate nanofiber precursor, and drying; Step six, calcining the dried nanofiber precursor at high temperature step by step in inert atmosphere, and cooling to obtain the titanium manganese sodium/carbon phosphate or chromium manganese sodium/carbon phosphate composite nanofiber anode material.
2. The method for preparing high-voltage manganese titanium phosphate and manganese chromium phosphate anode material nanofibers according to claim 1, wherein the organic phosphonic acid is 1-hydroxyethylidene-1, 1-diphosphonic acid (HEDP), and the heating temperature in the first step is 20-60 ℃.
3. The preparation method of the high-voltage manganese titanium phosphate and chromium manganese sodium phosphate positive electrode material nanofiber according to claim 1, wherein the organic solvent is one or more selected from ethanol, methanol and N, N-Dimethylformamide (DMF), the manganese source is selected from manganese acetate or manganese nitrate, the sodium source is selected from sodium acetate, sodium dihydrogen phosphate and sodium carbonate, the titanium source is selected from isopropyl titanate or tetrabutyl titanate, and the chromium source is selected from chromium nitrate or chromium acetate.
4. The method for preparing high-voltage titanium manganese sodium phosphate and chromium manganese sodium phosphate positive electrode material nanofibers according to claim 1, wherein in the fourth step, the mass-to-volume ratio of polyvinylpyrrolidone (PVP) to organic solvent is 0.025-0.1 g/mL, and the molar-to-volume ratio of metal ions to organic solvent in the spinning precursor solution is 0.05-0.6 mmol/mL.
5. The method for preparing high-voltage nano fibers of titanium manganese sodium phosphate and chromium manganese sodium phosphate anode materials according to claim 1, wherein the heating and sealing reaction temperature in the fourth step is 60-70 ℃ and the reaction time is 6-12 hours.
6. The method for preparing high-voltage nano fibers of titanium manganese sodium phosphate and chromium manganese sodium phosphate anode materials according to claim 1, wherein the electrostatic spinning parameters in the step five are that the spinning voltage is 15-25 kV, the receiving distance is 25-35 cm, the propelling flow rate is 0.10-0.15 mm/min, the ambient temperature is 45-55 ℃, and the relative humidity is 15% -25%.
7. The preparation method of the high-voltage titanium manganese sodium phosphate and chromium manganese sodium phosphate positive electrode material nanofiber according to claim 1 is characterized in that the step-by-step high-temperature calcination process in the step six is that the step-by-step high-temperature calcination process is carried out by heating to 200-300 ℃ at a heating rate of 2-5 ℃ per minute, preserving heat for 1-2 hours for pre-oxidation, heating to 600-800 ℃ at a heating rate of 2-5 ℃ per minute under nitrogen or argon atmosphere, and carrying out constant-temperature calcination for 2-6 hours.
8. A high voltage titanium manganese sodium phosphate or chromium manganese sodium phosphate positive electrode material nanofiber prepared by the method of any one of claims 1-7, wherein the material has a three-dimensional network nanofiber structure, and the surface of the material is coated with an in-situ generated carbon layer.
9. Use of the positive electrode material according to claim 8 in a sodium ion battery.

Description

High-voltage titanium manganese sodium phosphate and chromium manganese sodium phosphate positive electrode material nanofiber and preparation method thereof Technical Field The patent belongs to the field of sodium ion battery anodes and relates to high-voltage titanium manganese sodium phosphate and chromium manganese sodium phosphate anode material nanofibers and a preparation method thereof. Background In the background of increasing global energy demands, lithium ion batteries are facing a series of challenges such as resource shortage as an energy storage solution widely used at present. Sodium ion batteries are becoming an emerging energy storage technology, and are becoming a growing concern due to the advantages of abundant raw materials, low cost, environmental friendliness and the like. Meanwhile, the charge and discharge performance, energy density and cycle life of sodium batteries are continuously improved. Although the theoretical energy density and voltage plateau of sodium batteries is slightly lower than that of lithium batteries, sodium batteries have potential to replace lithium batteries in many application fields, particularly in low-cost, large-scale energy storage systems, such as power grid energy storage and non-high energy density demand scenarios of electric tools, through material innovation and optimal design. Therefore, the development of an electrode material with excellent performance, environmental friendliness and low cost is a target pursued by all scientific researchers. The positive electrode material is used as one of the key materials of the sodium ion battery and has the defects of lower capacity and lower energy density at present. In view of this, there is an urgent need to develop a high-voltage high-capacity battery positive electrode material. The NASICON type structural material shows a higher voltage platform and an excellent sodium ion migration channel by virtue of the unique structural characteristics of the NASICON type structural material. Sodium titanium manganese phosphate and sodium chromium manganese phosphate are representative materials for this structure. At present, the main preparation method of the material is a sol-gel method. However, this method has the disadvantages of complicated operation steps and long time consumption. In addition, the titanium manganese sodium phosphate and the chromium manganese sodium phosphate prepared by the sol-gel method are often accompanied by generation of hetero-phases, and the particles have uneven microscopic morphology and lower electronic conductivity. Due to the defects, the circulating performance and the voltage platform are poor, the impedance is high, and the ideal effect is difficult to achieve. In the prior art, the electrostatic spinning process of the sodium titanium phosphate/carbon composite material may have been studied and applied to a certain extent. However, it is not an easy matter to apply this process directly to the mixing of titanium manganese sodium phosphate, chromium manganese sodium phosphate precursors and high molecular weight polymers to form carbon composites. To achieve electrospinning, a suitable precursor solution needs to be prepared. The compatibility and mixing uniformity of the titanium manganese sodium phosphate precursor and the high molecular polymer may be a problem, the organic titanium source which is commonly selected at present is easy to hydrolyze and settle in water, spinning is difficult to carry out, and the organic solvent such as ethanol and N, N-Dimethylformamide (DMF) is used as the solvent, and the common sodium source and the phosphorus source (such as sodium dihydrogen phosphate and phosphorus pentoxide) are difficult to dissolve. In addition, the Cheng Zhongmeng source and chromium source synthesized in the titanium manganese sodium phosphate and chromium manganese sodium phosphate/carbon composite material may undergo polycondensation reaction with PVP, so that the fiber morphology is difficult to maintain in the pre-oxidation process, and the processes may need to be precisely controlled to avoid unnecessary side reactions or material degradation. Therefore, the preparation of the titanium manganese sodium phosphate and the chromium manganese sodium phosphate by adopting electrostatic spinning still has technical difficulties, and is still freshly reported at present. Disclosure of Invention The invention aims to solve the problems that in the preparation process of the existing titanium manganese sodium phosphate and chromium manganese sodium phosphate positive electrode materials, the conventional inorganic phosphorus source/sodium source has low solubility and poor compatibility in an organic spinning solvent, so that precursors are unevenly mixed, a heterogeneous phase is easy to generate after sintering, and the microscopic morphology is difficult to control. The invention provides a method for preparing high-voltage titanium manganese sodium p