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Method for large-scale characterization of lithium iron phosphate-amorphous carbon composite material

A technology of lithium iron phosphate and amorphous carbon, applied in the direction of material excitation analysis, Raman scattering, etc., can solve the problems of high cost, inability to evaluate the uniformity of coating, and unrepresentative test results, etc., and achieve the effect of simple operation

Active Publication Date: 2018-11-27
HEFEI GUOXUAN HIGH TECH POWER ENERGY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

At present, the evaluation of the amorphous carbon coating on the surface of lithium iron phosphate materials is mainly to measure the coating situation by measuring the content of carbon in the material in the macroscopic aspect, and to characterize the material by transmission electron microscope in the microscopic aspect, but these two methods are different. There are limitations. Measuring the carbon content in the material can only determine the amount of amorphous carbon in the material but cannot evaluate the uniformity of the coating; the use of transmission electron microscopy to characterize the material can accurately observe the coating of the material and measure the coating. Thickness, but the cost is higher and the test results are not representative

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  • Method for large-scale characterization of lithium iron phosphate-amorphous carbon composite material
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  • Method for large-scale characterization of lithium iron phosphate-amorphous carbon composite material

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Embodiment 1

[0024] A method for characterizing lithium iron phosphate-amorphous carbon composite material in a large area proposed by the present invention comprises the following steps:

[0025] S1. Place the lithium iron phosphate-amorphous carbon composite material powder on a glass sheet with a flat surface, and then press the powder with another glass sheet with a flat surface to compact it;

[0026] S2. Use Raman spectroscopy to test the compacted powder sample, adjust the test conditions so that the acquired Raman single spectrum is at 950cm -1 、1350cm -1 、1580cm -1 PO appears in the vicinity of the Raman shift 4 3+ , carbon D, carbon G characteristic peaks;

[0027] S3. From the obtained Raman single spectrum, two groups of test conditions with only different laser wavelengths are selected for the acquisition of large-area Raman imaging spectrum;

[0028] S4. Data processing is performed on the Raman imaging spectrum, and the PO in the spectrum is 4 3+ Peak intensity and PO...

Embodiment 2

[0030] A method for characterizing lithium iron phosphate-amorphous carbon composite material in a large area proposed by the present invention comprises the following steps:

[0031] S1. Place the lithium iron phosphate-amorphous carbon composite material powder on a glass sheet with a flat surface, and then press the powder with another glass sheet with a flat surface to compact it;

[0032] S2. Use Raman spectroscopy to test the compacted powder sample, adjust the test conditions so that the acquired Raman single spectrum is at 950cm -1 、1350cm -1 、1580cm -1 PO appears in the vicinity of the Raman shift 4 3+ , carbon D, carbon G characteristic peaks;

[0033] S3. From the obtained Raman single spectrum, two groups of test conditions with only different laser wavelengths are selected. The test conditions are 50 times objective lens, confocal pinhole 400, grating 600 (500nm), and the center of spectrum acquisition is 1200cm -1 , integration time 2-10s, cumulative times 2...

Embodiment 3

[0036] S1. Sample pretreatment: Weigh 0.1-0.5g of lithium iron phosphate-amorphous carbon composite material powder and place it on the surface of a clean and flat glass sheet, and then press another glass sheet with a clean and flat surface onto the powder Above, take it off carefully after compaction, it is required not to take off the powder and the surface of the powder is smooth;

[0037] S2. Acquisition of Raman single spectrum: Place the pole piece prepared in S1 on a glass sheet with a flat surface, and place the glass sheet on the sample test bench of a laser Raman instrument (HORRIBA, LabRAM HR Evol), and select test condition 1 : 50x objective lens, confocal pinhole 400, grating 600 (500nm), spectral center is 1200cm -1 , integration time 2-10s, cumulative times 2-5 times, laser at 532nm, output power 5-10mW; test condition 2: 50x objective lens, confocal pinhole 400, grating 600(500nm), spectrum center 1200cm -1 , The integration time is 2-10s, the accumulated tim...

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Abstract

The invention discloses a method for large-scale characterization of a lithium iron phosphate-amorphous carbon composite material, and relates to the technical field of lithium ion batteries. The method includes the following steps: placing lithium iron phosphate- amorphous carbon composite material powder on a glass sheet, and pressing the powder by another glass sheet for compaction; testing thepowder sample by using Raman spectra, adjusting test conditions to make the obtained Raman single spectrum show PO4<3+>, carbon D and carbon G characteristic peaks near Raman shifts of 950 cm<-1>, 1350 cm<-1> and 1580 cm<-1>; selecting the test conditions from the obtained Raman single spectrum for acquisition of large-area Raman imaging spectra; and carrying out data processing, imaging the intensity of the PO4<3+> peak in the spectrum and the intensity ratio of the PO4<3+> peak to the carbon G peak, and evaluating the uniformity of the amorphous carbon with which the surface of the lithiumiron phosphate is coated in the composite and the thickness of the coating layer according to data. The method can realize the characterization of the large-area lithium iron phosphate-amorphous carbon composite material by using a Raman spectrum imaging characterization method, and is simple and fast in operation.

Description

technical field [0001] The invention relates to the technical field of lithium ion batteries, in particular to a method for characterizing lithium iron phosphate-amorphous carbon composite materials in a large area. Background technique [0002] Lithium iron phosphate is a kind of positive electrode material of lithium ion battery. During the charging and discharging process, the volume of the positive electrode LiFePO4 only changes by 6.81%, which just adjusts the volume change caused by the deintercalation of lithium in the carbon negative electrode and supports the internal structure. Therefore, the lithium iron phosphate battery It shows good cycle stability and long cycle life during charge and discharge; however, lithium iron phosphate also has the disadvantages of poor conductivity and low ion diffusion rate. At present, in order to improve the conductivity of lithium iron phosphate materials, coating conductive materials on the surface of particles has become the mai...

Claims

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Application Information

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IPC IPC(8): G01N21/65
CPCG01N21/65
Inventor 夏劲罗瑞麻姗姗
Owner HEFEI GUOXUAN HIGH TECH POWER ENERGY