Search

CN-122010079-A - High-capacity ferric sodium pyrophosphate material and preparation method and application thereof

CN122010079ACN 122010079 ACN122010079 ACN 122010079ACN-122010079-A

Abstract

The invention discloses a high-capacity ferric sodium pyrophosphate material, a preparation method and application thereof, and belongs to the technical field of battery materials. The invention adopts the high-capacity ferric sodium phosphate material and the preparation method and application thereof, successfully solves the problem that the high compaction density and the long cycle life of the ferric sodium phosphate material cannot be considered through a synergistic process system of core-shell gradient carbon cladding and low-temperature reducing atmosphere sintering, utilizes common raw materials to construct spherical particles with an internal porous nano structure and an external carbon content gradient, combines low-temperature controllable reducing sintering, remarkably reduces energy consumption, and improves the intrinsic conductivity, structural stability and phase purity of the material, and the prepared material has high specific capacity close to a theoretical value, excellent multiplying power performance and ultra-long cycle life under extreme compaction conditions.

Inventors

  • XIE YUXIANG
  • LIU HONGYANG
  • FAN CHANGQIU
  • MA SHOUJUN
  • LIU CHUNYAN

Assignees

  • 兴荣新源(厦门)科技有限公司

Dates

Publication Date
20260512
Application Date
20260209

Claims (10)

  1. 1. A high-capacity ferric sodium pyrophosphate material is characterized by comprising the following raw materials of a phosphorus source, an iron source, a sodium source, a first carbon source, a second carbon source, a coating agent and a dispersing agent, wherein the atomic molar ratio of the phosphorus source, the iron source and the sodium source is Na: fe: P=4:3:5, and the first carbon source, the second carbon source, the coating agent and the dispersing agent respectively account for 2.5-5.5%, 1.0-2.4%, 0.4-2.1% and 0.1-0.5% of the total mass of the phosphorus source, the iron source, the sodium source, the first carbon source, the second carbon source, the coating agent and the dispersing agent.
  2. 2. The high-capacity ferric sodium pyrophosphate material according to claim 1, wherein the sodium source is one of sodium carbonate, sodium bicarbonate, sodium nitrate and sodium sulfate, the phosphorus source is one of ammonium dihydrogen phosphate, diammonium hydrogen phosphate and ammonium phosphate, the iron source is one of ferrous sulfate and ferric nitrate, the first carbon source is one of citric acid and tartaric acid, the second carbon source is one of glucose and sucrose, the coating agent is one of L-ascorbic acid and maltodextrin, and the dispersing agent is one of polyethylene glycol and polyvinyl alcohol.
  3. 3. The method for preparing the high-capacity ferric sodium phosphate material according to any one of claims 1 to 2, which is characterized by comprising the following steps: firstly, preparing precursor slurry, namely weighing a sodium source, a phosphorus source and an iron source to prepare the precursor slurry; Step two, spray drying and granulating, namely adding a second carbon source into the precursor slurry, uniformly stirring to obtain mixed slurry, and spray drying the mixed slurry to obtain spherical precursor powder; step three, sintering the spherical precursor powder to obtain a sintered product; And fourthly, crushing and sieving the sintered product to obtain the high-capacity ferric sodium phosphate material.
  4. 4. The method for preparing high-capacity ferric sodium phosphate material according to claim 3, wherein the specific operation of the first step is as follows: s1, dissolving a sodium source and a phosphorus source in deionized water, and stirring until the mixture is clear to obtain a sodium-phosphorus mixed solution; s2, dissolving an iron source, a first carbon source, a coating agent and a dispersing agent in deionized water to obtain an iron source mixed solution; S3, dropwise adding the iron source mixed solution into the sodium-phosphorus mixed solution under the protection of nitrogen, controlling the reaction pH, and stirring for reaction to obtain precursor slurry.
  5. 5. The method for preparing high-capacity ferric sodium phosphate material as claimed in claim 3, wherein in S1, the deionized water is at a temperature of 60-70 ℃; In S3, the dropping speed of the iron source mixed solution is 0.5-2mL/min, the reaction pH is 4.5-5.5, the reaction temperature is 65-75 ℃, and the stirring reaction is carried out for 3-5h.
  6. 6. The method for preparing high-capacity ferric sodium phosphate material as claimed in claim 3, wherein in the second step, the spray drying parameters are that a pressure type or centrifugal spray dryer is adopted, the inlet temperature is controlled to be 200-230 ℃, and the outlet temperature is controlled to be 95-110 ℃.
  7. 7. The method for preparing high-capacity ferric sodium phosphate material as claimed in claim 3, wherein in the third step, gradient sintering is adopted for sintering, and the method comprises three stages: The first stage, heating from room temperature to 300-350 ℃ at 3-5 ℃ per min, and preserving heat for 0.5-1h under argon atmosphere; The second stage, namely heating to 570-590 ℃ at a temperature of 2-3 ℃ per minute after heat preservation, switching to argon-hydrogen mixed gas, and preserving heat for 2-4 hours; And third stage, switching to argon after heat preservation is finished, and cooling to room temperature along with the furnace.
  8. 8. The method of claim 7, wherein the argon-hydrogen mixture in the second stage has a hydrogen volume fraction of 1-3%.
  9. 9. The method for preparing high-capacity ferric sodium phosphate material as claimed in claim 3, wherein in the fourth step, the sieving mesh is 300-400 meshes.
  10. 10. The application of the high-capacity ferric sodium phosphate material is characterized in that the high-capacity ferric sodium phosphate material as claimed in any one of claims 1-2 is applied to the preparation of sodium ion batteries.

Description

High-capacity ferric sodium pyrophosphate material and preparation method and application thereof Technical Field The invention relates to the technical field of battery materials, in particular to a high-capacity sodium ferric pyrophosphate material, a preparation method and application thereof. Background With the shift of global energy structures to clean and low-carbonization, large-scale energy storage technology becomes a key for supporting the development of renewable energy sources. Sodium ion batteries are considered as one of candidate technologies with the most application potential in the field of large-scale energy storage because of abundant sodium resource reserves, wide distribution and low cost, and the electrochemical principle is similar to that of lithium ion batteries. Among the positive electrode materials of sodium ion batteries, polyanion compounds, particularly sodium iron pyrophosphate (Na 4Fe3(PO4)2P2O7, abbreviated as NFPP) having NASICON (sodium super ion conductor) crystal structure, have been receiving attention because of their stable three-dimensional framework structure, moderate operating voltage, higher theoretical specific capacity, and characteristics of environmental friendliness, safety and non-toxicity. However, the industrialized application of NFPP materials still faces a series of key technical challenges, namely firstly, the intrinsic electronic conductivity is lower, the full play and multiplying power performance of the capacity are severely limited, secondly, the structural stability of the materials is subject to examination in the circulating process, particularly under the condition of high compaction density, the capacity attenuation is faster, namely, the industrial common problem that the high compaction density and the long cycle life are difficult to be compatible exists, and furthermore, the traditional preparation process mostly adopts a high-temperature solid-phase method (the sintering temperature is usually higher than 700 ℃), so that not only is the energy consumption high, but also sodium volatilization, iron oxidation and generation of impurity phases (such as NaFePO 4、Fe2O3 and the like) are easily caused, and the phase purity and the electrochemical performance of the materials are damaged. Carbon coating is a widely used effective means for improving conductivity. However, in the prior art, a single carbon source (such as glucose and sucrose) is adopted for simple coating, and the formed carbon layer has a single structure, so that multiple requirements of high electronic conductivity, strong interface binding force and effective buffer volume change are difficult to meet. While a uniform thick carbon layer improves conductivity, it impedes ion transport and reduces volumetric energy density, a thin or incomplete carbon layer has limited protective effect. Furthermore, conventional coating processes coupled with high temperature sintering processes may result in excessive graphitization of the carbon layer at high temperatures or adverse reactions with the active species. Disclosure of Invention The invention aims to provide a high-capacity ferric sodium phosphate material, a preparation method and application thereof, wherein the problem that the high compaction density and the long cycle life of the ferric sodium phosphate material cannot be considered is successfully solved through a core-shell gradient carbon cladding and low-temperature reducing atmosphere sintering synergistic process system, spherical particles with an internal porous nano structure and an external carbon content gradient are constructed by common raw materials, the low-temperature controllable reducing sintering is combined, the energy consumption is obviously reduced, the intrinsic conductivity, the structural stability and the phase purity of the material are greatly improved, and the prepared material has high specific capacity close to a theoretical value, excellent multiplying power performance and ultra-long cycle life under an extreme compaction condition. In order to achieve the aim, the invention provides a high-capacity ferric sodium phosphate material which comprises the following raw materials of a phosphorus source, an iron source, a sodium source, a first carbon source, a second carbon source, a coating agent and a dispersing agent, wherein the atomic molar ratio of the phosphorus source, the iron source and the sodium source is Na: fe: P=4:3:5, and the first carbon source, the second carbon source, the coating agent and the dispersing agent respectively account for 2.5-5.5%, 1.0-2.4%, 0.4-2.1% and 0.1-0.5% of the total mass of the phosphorus source, the iron source, the sodium source, the first carbon source, the second carbon source, the coating agent and the dispersing agent. Preferably, the sodium source is one of sodium carbonate, sodium bicarbonate, sodium nitrate and sodium sulfate, the phosphorus source is one of ammonium dihydrogen phosphate, d