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Composite sodium ion positive electrode material with core-shell structure and preparation method thereof

A positive electrode material, sodium ion battery technology, applied in structural parts, battery electrodes, electrical components, etc., can solve the problems of large sodium layer spacing, limited industrial application and promotion, and low specific capacity, so as to reduce production and storage costs , large commercial application prospects, and the effect of simple preparation methods

Active Publication Date: 2019-03-08
CENT SOUTH UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, layered cathode materials with two-dimensional sodium ion diffusion channels are sensitive to water and carbon dioxide in the air, and exposure to air will cause sodium ions to diffuse from the interlayer to the surface and react with water and carbon dioxide in the air to generate damage to the material. Sodium hydroxide and sodium carbonate with unfavorable electrochemical properties, at the same time, due to the loss of sodium ions, the structure of the layered material will be degraded, and the electrochemical performance will deteriorate; in addition, after the sodium ions are released during the charge and discharge process, the sodium interlayer spacing becomes larger, Part of the solvent molecules enter the layered material, resulting in a decrease in the structural stability of the material and poor cycle stability. These shortcomings have brought a lot of inconvenience to the production, transportation and storage of the layered sodium ion battery cathode material, limiting its use. Industrial application promotion
Another kind of positive electrode material is the positive electrode material of sodium ion battery with a tunnel-like structure. Although it has a three-dimensional sodium ion diffusion channel, its structure is stable, and it is not easy to react with water and oxygen in the air, but this structure is not conducive to the flow of solvent molecules into the material. Diffusion, therefore lower specific capacity

Method used

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  • Composite sodium ion positive electrode material with core-shell structure and preparation method thereof
  • Composite sodium ion positive electrode material with core-shell structure and preparation method thereof

Examples

Experimental program
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Effect test

Embodiment 1

[0017] (1) The layered structure material Na synthesized by 4mmol hydrothermal method 0.5 mn 0.5 Ni 0.5 o 2 , added to 40mL of absolute ethanol, and then added 0.4mmol sodium acetate, 0.66mmol manganese acetate and 0.34mmol tetrabutyl titanate, stirred for 20min and then ultrasonically dispersed for 5min to form a dispersion system; then the dispersion system was placed at 60°C environment until the ethanol is completely evaporated to obtain a uniformly mixed powder material;

[0018] (2) Put the above-mentioned powder material in an alumina boat, and heat-treat it in a muffle furnace. The process parameters are 1°C / min to 450°C, heat preservation for 5 hours, and then 3°C / min to 900°C, and heat preservation for 15 hours. hours, and then cooled to room temperature.

[0019] Adopt above-mentioned method to make a kind of composite sodium ion battery cathode material, have shell-core structure, internal chemical composition is Na 0.5 mn 0.5 Ni 0.5 o 2 , layered structure...

Embodiment 2

[0022] (1) The layered structure material Na synthesized by 5.67mmol coprecipitation method 0.5 mn 0.8 co 0.2 o 2 Add to 40mL deionized water, then add 0.5mmol sodium nitrate, 0.5mmol manganese nitrate, 0.5mmol tetrabutyl titanate to it, stir for 30min, evaporate the solvent water in a water bath at 80°C to obtain a uniformly mixed powder;

[0023] (2) Put the above powder in an alumina boat and heat treat in a muffle furnace. The process parameters are 1°C / min to 500°C, heat preservation for 5 hours, 2°C / min temperature rise to 950°C, heat preservation for 10 hours, and then Naturally cool to room temperature.

[0024] Adopt above-mentioned method to make a kind of composite sodium ion battery cathode material, have core-shell structure, internal chemical composition is Na 0.5 mn 0.8 co 0.2 o 2 , layered structure, accounting for 85% of the total molar ratio; the surface chemical composition is Na 0.5 mn 0.5 Ti 0.5 o 2 , by XRD analysis, the characteristic peaks of...

Embodiment 3

[0026] (1) Grind 0.6mmol sodium nitrate, 0.7mmol manganese acetate, and 0.3mmol titanium dioxide in a mortar evenly, then add 7mmol layered structure material NaMn synthesized by solution combustion method 0.5 V 0.2 Ti 0.3 O continue to grind until evenly mixed;

[0027] (2) Put the above-mentioned uniformly mixed powder in an alumina boat and heat-treat in a muffle furnace. The process parameters are 1°C / min to 400°C, heat preservation for 6 hours, 5°C / min to 900°C, heat preservation 12 hours, then naturally cooled to room temperature.

[0028] A composite sodium-ion battery positive electrode material is prepared by the above method, which has a shell-core structure and an internal chemical composition of NaMn 0.5 V 0.2 Ti 0.3 o 2 , layered structure, accounting for 87.5% of the total molar ratio; the surface chemical composition is Na 0.6 mn0.7 Ti 0.3 o 2 According to XRD analysis, the characteristic peaks of tunnel-like structure appear on the spectrum at 14°, 16....

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Abstract

The invention provides a composite sodium ion battery positive electrode material and a preparation method thereof. The material has a shell-core structure; the interior of the material is of a layered structure; and the surface of the material is of a tunnel-shaped structure. By adopting a simple secondary sintering method, raw materials are dispersed on the surface of a layered material througha wet mixing or dry mixing method; a layer of the stable tunnel-shaped structure is generated on the surface of the layered material in situ; and the sodium ion composite positive electrode material with the layered and tunnel-shaped core-shell structure is obtained. The composite sodium ion battery positive electrode material has the advantages of high capacity of the layered material and high stability of the tunnel-shaped structure, and can be stably stored in air, and the cycling stability and the high-power performance are both superior to those of the single layered material or tunnel-shaped structure material. Moreover, the preparation method is simple and low in cost, is capable of effectively reducing the production and storage costs of the layered material, and has relatively high commercial application prospects.

Description

technical field [0001] The invention relates to a battery cathode material and a preparation method, in particular to a sodium ion battery cathode material and a preparation method. Background technique [0002] Sodium, which has similar chemical properties to lithium, is abundant in the earth's crust and widely distributed, so sodium-ion batteries are considered to be the most promising secondary batteries to replace lithium-ion batteries in the field of large-scale energy storage. Currently layered transition metal oxides Na x TMO 2 (TM: one or more transition metal elements) is an important cathode material for sodium-ion batteries, which has attracted people's attention due to its high specific capacity, simple preparation method, and low price. However, layered cathode materials with two-dimensional sodium ion diffusion channels are sensitive to water and carbon dioxide in the air, and exposure to air will cause sodium ions to diffuse from the interlayer to the surfac...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/36H01M10/054H01M4/485H01M4/505H01M4/525H01M4/38
CPCH01M4/366H01M4/381H01M4/485H01M4/505H01M4/525H01M10/054Y02E60/10
Inventor 韦伟峰肖蕾黄群杨颖张春晓黄伯云
Owner CENT SOUTH UNIV
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