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Lithium cobalt phosphate-coated lithium-rich positive electrode material and preparation method thereof

A lithium-rich cathode material, lithium cobalt phosphate technology, applied in battery electrodes, electrical components, electrochemical generators, etc., can solve the problems of poor cycle performance of lithium-rich cathode materials, low initial coulombic efficiency of lithium-rich cathode materials, etc., to achieve The effect of improving the stability of the surface structure, the preparation method is simple, and the cycle performance is improved

Inactive Publication Date: 2018-06-15
HEFEI GUOXUAN HIGH TECH POWER ENERGY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Because of this irreversible activation process and the decomposition of the electrolyte at high voltage, the first coulombic efficiency of Li-rich cathode materials is low.
The transformation of lithium-rich cathode materials from layered structure to spinel structure during charge and discharge is the main reason for the poor cycle performance of lithium-rich cathode materials.

Method used

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  • Lithium cobalt phosphate-coated lithium-rich positive electrode material and preparation method thereof
  • Lithium cobalt phosphate-coated lithium-rich positive electrode material and preparation method thereof
  • Lithium cobalt phosphate-coated lithium-rich positive electrode material and preparation method thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0026] (1)Li 1.2 Mn 0.54 Ni 0.13 Co 0.13 O 2 Preparation

[0027] Measure LiCOOCH according to the molar ratio Li:Mn:Ni:Co is 1.32:0.54:0.13:0.13 3 ·2H 2 O, Mn(COOCH 3 ) 2 , Ni(COOCH 3 ) 2 ·4H 2 O, Co(COOCH 3 ) 2 ·4H 2 O, dissolved in 100 mL of deionized water to obtain a mixed salt solution; then a certain amount of citric acid (citric acid: metal ion = 4:1 molar ratio) was dissolved in 50 mL of deionized water and stirred evenly; slowly added the citric acid aqueous solution to In the mixed salt solution, heat to 80°C and magnetically stir for 4 hours to form a pink transparent gel. The gel is transferred to a blast drying oven at 80°C for 12 hours and pre-burned in a box furnace under an air atmosphere of 480°C After 5 hours, take it out and grind it, and then move it into a muffle furnace for calcination at 900°C for 12 hours. The heating rate of the calcination stage is 4°C / min, and Li can be obtained. 1.2 Mn 0.54 Ni 0.13 Co 0.13 O 2 (LMNCO) powder.

[0028] (2)LiCoPO 4 Coated...

Embodiment 2

[0033] (1)Li 1.2 Mn 0.54 Ni 0.13 Co 0.13 O 2 Preparation

[0034] Measure LiCOOCH according to the molar ratio Li:Mn:Ni:Co is 1.32:0.54:0.13:0.13 3 ·2H 2 O, Mn(COOCH 3 ) 2 , Ni(COOCH 3 ) 2 ·4H 2 O, Co(COOCH 3 ) 2 ·4H 2 O, dissolved in 100 mL of deionized water to obtain a mixed salt solution; then a certain amount of citric acid (citric acid: metal ion = 4:1 molar ratio) was dissolved in 50 mL of deionized water and stirred evenly; slowly added the citric acid aqueous solution to The mixed salt solution is heated to 80°C and magnetically stirred at a speed of 180r / min for 4 hours to form a pink transparent gel. Transfer the gel to a blast drying oven at 80°C for 12 hours, pre-burn in a box furnace at 480°C for 5 hours, take it out and grind, and then move it into a muffle furnace at 900°C for 12 hours. The heating rate during the calcination stage At 4℃ / min, Li can be obtained 1.2 Mn 0.54 Ni 0.13 Co 0.13 O 2 (LMNCO) powder.

[0035] (2)LiCoPO 4 Coated Li 1.2 Mn 0.54 Ni 0.13 Co 0.1...

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Abstract

The invention discloses a lithium cobalt phosphate-coated lithium-rich positive electrode material and a preparation method thereof, and belongs to the technical field of a lithium ion battery. The material comprises a lithium-rich material and lithium cobalt phosphate, wherein the lithium cobalt phosphate is coated on a surface of the lithium-rich material, the chemical formula of the material isLiCoPO4----Li<1.2>Mn<0.54>Ni<0.13>Co<0.13>O<2>, the structure is a layered Alpha-NaFeO2 structure, a layered space group is R<3>m, and the mass percent of the lithium cobalt phosphate accounts for 3-7%. By coating a surface of a lithium-rich positive electrode with amorphous LiCoPO4, the surface structural stability of the material is improved, meanwhile, extra discharging capacity can be provided, the initial coulombic efficiency of the coated material reaches 84.14%, the discharge specific capacity under 0.1C current reaches 305.95mAh / g, particularly, the cycle property of a sample after being coated can be greatly improved, and the capacity retention rate after circulation for 100 times under 1C rate is 88.2% much higher than 72.3% of a sample which is not coated. The preparation method is simple, the surface structure is improved (direct contact with an electrolyte is reduced, and Mn dissolution is suppressed), and the material has high discharge capacity and excellent rate performance and cycle property.

Description

Technical field [0001] The invention relates to the technical field of lithium ion batteries, in particular to a lithium-rich cathode material coated with lithium cobalt phosphate and a preparation method thereof. Background technique [0002] Lithium-rich cathode material Li 1+x / (x+2) M (2-2x) / (x+2) Mn 2x / (x+2) O 2 Or xLi 2 MnO 3 ·(1-x)LiMO 2 (M stands for transition metal element) has high reversible capacity (> 250mAh / g) and low cost, but there are also shortcomings such as low first-time Coulomb efficiency and insufficient cycle life, which severely restrict the application of lithium-rich cathode materials in practice. The high capacity of lithium-rich cathode materials comes from the high voltage Li 2 MnO 3 Activation process, that is, Li in the lattice 2 The irreversible release of O is accompanied by the generation of oxygen vacancies. Because of this irreversible activation process and the decomposition of the electrolyte under high voltage, the first coulombic effici...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/36H01M4/525H01M4/505H01M10/0525
CPCH01M4/366H01M4/505H01M4/525H01M10/0525Y02E60/10
Inventor 何磊王庆莉李道聪
Owner HEFEI GUOXUAN HIGH TECH POWER ENERGY
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