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A method for large-area characterization of lithium iron phosphate-amorphous carbon composites

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: 2021-02-26
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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  • A method for large-area characterization of lithium iron phosphate-amorphous carbon composites
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  • A method for large-area characterization of lithium iron phosphate-amorphous carbon composites

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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 characterizing a lithium iron phosphate-amorphous carbon composite material in a large area, relates to the technical field of lithium ion batteries, and comprises the following steps: placing a lithium iron phosphate-amorphous carbon composite material powder on a glass sheet, and using Another glass sheet presses the powder and compacts it; the Raman spectrum is used to test the powder sample, and the test conditions are adjusted 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, and Carbon G characteristic peaks; the test conditions are screened out from the acquired Raman single spectrum for the acquisition of large-area Raman imaging spectra; data processing is performed to analyze the PO in the spectrum 4 3+ Peak intensity and PO 4 3+ The peak intensity ratio of the peak to the carbon G peak was imaged, and the uniformity of the amorphous carbon coating on the surface of lithium iron phosphate in the composite material and the thickness of the coating layer were evaluated according to the data. The present invention uses the Raman spectrum imaging characterization method to realize the characterization of large-area lithium iron phosphate-amorphous carbon composite materials, and the operation is simple and fast.

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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Patent Type & Authority Patents(China)
IPC IPC(8): G01N21/65
CPCG01N21/65
Inventor 夏劲罗瑞麻姗姗
Owner HEFEI GUOXUAN HIGH TECH POWER ENERGY