Lithium manganese silicate/carbon composite material doped with alkaline-earth metal ions and preparing method thereof

A carbon composite material, silicon-manganese acid-based technology, applied in nanotechnology, electrical components, electrochemical generators, etc. for materials and surface science, can solve the problem of low electronic conductivity and ion diffusion rate, which cannot meet the growing Requirements, constraints on electrochemical performance and other issues, to achieve the effect of improving rate performance, improving electrochemical performance, and uniform morphology

Active Publication Date: 2018-01-05
CENT SOUTH UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0002] Due to the positive electrode materials currently used in lithium-ion batteries (such as layered transition metal oxides (LiMO 2 ), spinel lithium manganate (LiMn 2 o 4 ) and olivine-type lithium iron phosphate (LiFePO 4 )) There are different defects: poor safety performance, low energy density or poor conductivity, etc., can no longer meet the growing demand for energy equipment under the current energy crisis and greenhouse effect
However, the performance of the lithium-ion battery cathode material greatly limits its application, and the shortcomings of the material's poor cycle stability, low electronic conductivity and low ion diffusivity severely restrict its electrochemical performance and restrict its Commercial promotion and application

Method used

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  • Lithium manganese silicate/carbon composite material doped with alkaline-earth metal ions and preparing method thereof
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  • Lithium manganese silicate/carbon composite material doped with alkaline-earth metal ions and preparing method thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0027] A silicomanganate-based lithium / carbon composite material, the chemical formula is Li 2 Mn 0.95 Ca 0.05 SiO 4 / C, the mass of carbon in the material accounts for 19-20% of the total mass of the material; the material is tested by XRD and refined analysis, such as figure 1 As shown, the material is orthorhombic, Pmn2 1 Space group; after measurement, the b axis of the material unit cell parameter is a axis is c axis is figure 2 Is a picture under a high resolution transmission electron microscope, such as figure 2 As shown, the material is in the form of 2-20nm nanorods or nanosheets. figure 2 The picture is obtained by Fourier transform (FFT) image 3 , As shown in the figure is the diffraction spot picture. After calibration, it is found that these crystal grains are [001] with axis, showing the characteristics of (001) crystal plane exposure; the material is tested by X-ray photoelectron spectroscopy, and the results are as follows Figure 4 As shown, the concentrati...

Embodiment 2

[0030] Prepare the composite material of Example 1 according to the following steps:

[0031] (I) At room temperature, weigh 40mmol of LiOH and dissolve in 40mL of diethylene glycol to make the pH value 10. Then add 10mmol of tetraethyl silicate and stir for 50 minutes until the tetraethyl silicate is complete Dissolve to obtain solution A, in which the molar mass ratio of Li element to Si element is 4:1; add 9.5mmol MnCl 2 ·4H 2 O and 0.5mmol CaCl 2 Dissolve in 20mL diethylene glycol to obtain solution B;

[0032] (II) Add the solution B prepared in step (I) dropwise to solution A, keeping the pH of the system unchanged, then the mixed solution is reacted for 72 hours at a pressure of 4Mpa and a temperature of 230°C, and then naturally cooled to room temperature; After centrifugal separation, the product was centrifuged and washed with deionized water and ethanol for several times until the solvent after washing became neutral, and then the solid product was vacuum dried at 80°C t...

Embodiment 3

[0035] A silicomanganate-based lithium / carbon composite material, the chemical formula is Li 2 Mn 0.95 Mg 0.05 SiO 4 / C, the mass of carbon in the material accounts for 19-20% of the total mass of the material; the material is detected by XRD and refined analysis, the material is orthorhombic, Pmn2 1 Space group, the b-axis of the material unit cell parameter is a axis is c axis is The material is composed of 5-50nm nanosheets and nanorod particles. The material shows [001] axis spots under a high-resolution transmission electron microscope, showing the characteristics of (001) crystal plane exposure; X-ray photoelectron spectroscopy is performed on the material In the test, lithium and silicon are enriched on the surface of the material, while manganese and magnesium are enriched in the material.

[0036] The preparation method is as follows:

[0037] (I) At room temperature, weigh 20mmol of LiOH and dissolve it in 40mL of diethylene glycol to make the pH value 10. Then add 5mmo...

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Abstract

The invention provides a lithium manganese silicate / carbon composite material doped with alkaline-earth metal ions and a preparing method thereof. The chemical formula of the material is Li2Mn(1-x)MxSiO4 / C, wherein 0<x<=0.10, and M is selected from one of Mg, Ca, Sr or Ba. The material displays [001] spots with axes under a high-resolution transmission electron microscopy, and is prepared based on the principle of a hydrothermal method. The lithium manganese silicate / carbon composite material is uniform in shape and high in degree of crystallinity, [001] crystal faces are exposed, and due todoping of alkaline-earth metal elements, the lattice constants of the material are changed; meanwhile, all the elements show the features that concentrations are distributed in a gradient mode, thus promoting of electrical conductivity is facilitated, and the material has excellent electrochemical performance under high magnification.

Description

Technical field [0001] The invention relates to a lithium battery positive electrode active material and a preparation method, in particular to an ion-doped silicomanganate-based lithium / carbon composite material and a preparation method. Background technique [0002] As the cathode materials currently used in lithium-ion batteries (such as layered transition metal oxides (LiMO 2 ), spinel lithium manganate (LiMn 2 O 4 ) And olivine-type lithium iron phosphate (LiFePO 4 )) All have different defects: poor safety performance, low energy density or poor conductivity, etc., which can no longer meet the increasing demand for energy equipment under the current energy crisis and the greenhouse effect. This forces researchers to actively develop and research new generation lithium-ion battery cathode materials with high energy density, good safety, environmental friendliness and low cost. [0003] Lithium Manganese Silicate (Li 2 MnSiO 4 ) Material is a new type of polyanionic lithium ion...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/36H01M4/58H01M4/587H01M4/62H01M10/0525B82Y30/00B82Y40/00
CPCY02E60/10
Inventor 韦伟峰冯伊铭冀然丁正平
Owner CENT SOUTH UNIV
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