Modification method of high-rate lithium-rich cathode material

A lithium-rich positive electrode material and high-rate technology, applied in battery electrodes, electrical components, circuits, etc., can solve the problems that cannot meet the needs of fast charging of electric equipment

Active Publication Date: 2014-03-05
BEIJING UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

In recent years, scholars at home and abroad have coated the surface of lithium-rich cathode materials with inert oxides (Al 2 o 3 、TiO 2 , RuO 2 etc.) to improve its electrochemical performance, but they can only obtain higher capacity when they are discharged at a high rate after low-rate charging. Modified (AlPO 4 +Al 2 o 3 、Al 2 o 3 +RuO 2 ), charging at a low rate (C / 20), the discharge capacity is about 200mAh / g at 2C, and only 150mAh / g at 5C, which cannot meet the requirements of fast charging for electric equipment

Method used

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  • Modification method of high-rate lithium-rich cathode material
  • Modification method of high-rate lithium-rich cathode material
  • Modification method of high-rate lithium-rich cathode material

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Experimental program
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Effect test

Embodiment 1

[0022] 1. According to the molecular formula Li[Ni 0.2 Li 0.2 mn 0.6 ]O 2 The ratio of Li, Ni, Mn to prepare LiNO 3 , Ni(NO 3 ) 2 and Mn(NO 3 ) 2 Mixed solution, the total metal ion concentration is 1mol / L;

[0023] 2. Configure the citric acid solution according to the ratio of citric acid: total metal ions = 1:1 (molar ratio). Under strong stirring, add the mixed solution of the metal salt dropwise to the citric acid solution, stir and heat in a water bath at 80°C until Yellow-green gel, dry and slightly fluffy bulk precursor after drying in a vacuum oven at 150°C for 12 hours;

[0024]3. Heat the precursor obtained above at 480°C for 10 hours in an air atmosphere, then heat it up to 750°C for 15 hours, and cool it to room temperature with the furnace to obtain the lithium-ion battery cathode material Li[Ni 0.2 Li 0.2 mn 0.6 ]O 2 .

[0025] 4. Disperse the obtained lithium-rich cathode material in 0.284g / L NH 4 h 2 PO 4 Sonicate the solution for 1 hour, then ...

Embodiment 2

[0030] 1-3 steps are the same as embodiment 1;

[0031] 4. Disperse the lithium-rich cathode material prepared above in 0.426g / L NH 4 h 2 PO 4 Sonicate the solution for 1 hour, then stir vigorously for 2 hours, and drop NH with a concentration of 0.434 g / L into it 4 VO 3 solution, stirred for 1 hour, evaporated to dryness in a water bath at 80°C, and dried at 80°C;

[0032] 5. Then sinter at 400°C for 6 hours to obtain surface-modified Li[Ni 0.2 Li 0.2 mn 0.6 ]O 2 .

[0033] X-ray diffraction (XRD) analysis showed that the main phase of the product was Li[Ni 0.2 Li 0.2 mn 0.6 ]O 2 ( figure 1 The spectrum corresponding to 6wt.% of the middle coating rate), only Li appeared between 20-35° 3 PO 4 The miscellaneous peaks (marked with an asterisk), whose structure has not been destroyed.

[0034] Electrochemical tests show that when charging and discharging at 1C and 3C, the initial discharge capacity is 250mAh / g (see figure 2 6wt.% corresponding graph) and 213mAh...

Embodiment 3

[0036] 1-3 steps are the same as embodiment 1;

[0037] 4. Disperse the obtained lithium-rich cathode material in 0.568g / L NH 4 h 2 PO 4 Sonicate the solution for 1 hour, then stir vigorously for 2 hours, and drop NH with a concentration of 0.578 g / L into it 4 VO 3 solution, stirred for 1 hour, evaporated to dryness in a water bath at 80°C, and dried at 80°C;

[0038] 5. Then sinter at 400°C for 6 hours to obtain surface-modified Li[Ni 0.2 Li 0.2 mn 0.6 ]O 2 .

[0039] X-ray diffraction (XRD) analysis showed that the main phase of the product was Li[Ni 0.2 Li 0.2 mn 0.6 ]O 2 ( figure 1 The spectrum corresponding to 8wt.% of the medium coating rate), only Li appears between 20-35° 3 PO 4 The miscellaneous peaks (marked with an asterisk), whose structure has not been destroyed.

[0040] Electrochemical tests show that when charging and discharging at 1C and 3C, the first discharge capacity is 252mAh / g (see figure 2 Covering rate 8wt.% corresponding graph) and 1...

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Abstract

The invention relates to a modification method of a high-rate lithium-rich cathode material, belonging to the technical field of cathode materials of lithium ion cells. The modification method comprises the steps of: ultrasonically dispersing Li[NixLi1 / 3-2x / 3Mn2 / 3-x / 3]O2 in NH4H2PO4 solution with concentration not more than 0.710g / L for 1h, stirring for 2h, dripping NH4VO3 solution with concentration not more than 0.722g / L at a molar ratio of NH4H2PO4 to NH4VO3 being 1:1, stirring for 1h, evaporating to be dry in 80 DEG C water bath, and drying at 80 DEG C; and burning dried Li[NixLi1 / 3-2x / 3Mn2 / 3-x / 3]O2 at 300-500 DEG C for 4-15h. According to the invention, not only is the first irreversible capacity loss of the lithium-rich cathode material reduced, but also the rate performance of the lithium-rich cathode material is greatly improved, thus the requirements of high-power lithium ion cells are satisfied.

Description

technical field [0001] The invention relates to a surface modification method for high-rate lithium-rich cathode materials, and belongs to the technical field of cathode materials for lithium-ion batteries. Background technique [0002] In recent years, under the environment of soaring gasoline prices and global advocacy of new energy, energy saving and emission reduction, and low-carbon economy, lithium-ion batteries with high energy density and high power density have become the focus of attention. While the commercialized LiCoO 2 , LiMn 2 o 4 、LiFePO 4 Due to the relatively low capacity, it cannot meet the high requirements of 3G electronic products and electric vehicles for lithium-ion battery cathode materials, so lithium-rich cathode materials with higher voltage and higher specific capacity have become a research hotspot. [0003] Lithium-rich cathode materials for lithium-ion batteries are mainly layered materials Li 2 MnO 3 with LiMO 2 (M=Ni, Co, Ni 0.5 mn ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01M4/62H01M4/36
CPCY02E60/12Y02E60/10
Inventor 赵煜娟郭彩霞孙国平任文锋吴锐
Owner BEIJING UNIV OF TECH
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