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Method for synthesizing LiFePO4/C material based on chemical gas phase sediment auxiliary solid phase method

A technology of chemical vapor deposition and solid phase method, applied in chemical instruments and methods, inorganic chemistry, phosphorus compounds, etc., can solve the problems of uneven particle size distribution, low electronic conductivity, high synthesis temperature, etc., and achieve improved magnification Charge-discharge and cycle performance, improved uniformity and conductivity, simple preparation process

Inactive Publication Date: 2008-08-06
SHANGHAI CHIYUAN NEW MATERIAL TECH
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

But LiFePO 4 There are also the following three problems in the positive electrode material: (1) Fe in the synthesis 3+ easily oxidized to Fe 3+ , it is not easy to obtain single-phase LiFePO 4 ; (2) LiFePO 4 Low electronic conductivity (10 -9 ~10 -10 S / cm) and lithium ion diffusion coefficient (1.8×10 -14 cm 2 / S), resulting in extremely poor rate charge and discharge performance; (3) low tap density, resulting in low volume specific energy
Due to the shortcomings of high synthesis temperature, large particles, and uneven particle size distribution, this method cannot completely solve the inherent limitations of the material.

Method used

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  • Method for synthesizing LiFePO4/C material based on chemical gas phase sediment auxiliary solid phase method
  • Method for synthesizing LiFePO4/C material based on chemical gas phase sediment auxiliary solid phase method

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Experimental program
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Effect test

Embodiment 1

[0030] Will Li 2 CO 3 , FeC 2 o 4 2H 2 O and NH 4 h 2 PO 4 Weigh 25g according to the stoichiometric ratio of Li:Fe:P=1:1:1, mix evenly, and ball mill for 6h on a planetary ball mill; 2 Pre-fired at 300°C for 5 hours in the atmosphere, ball milled for 2 hours after natural cooling to obtain powder materials; transferred to a tube furnace to heat at a heating rate of 30°C / min, and used benzene as an organic precursor, and carbonized on the surface of the material by chemical vapor deposition. Coating, gas flow rate 50mL / min, calcination at constant temperature of 600°C for 8h. Lithium-ion battery lithium iron phosphate (LiFePO 4 ) positive electrode material. The average particle size of the material is measured to be 2~10μm, and the tap density is 1.65g / cm 3 .

[0031]The XRD of the product is shown in the curve a in Figure 1. It can be seen from the figure that a pure-phase orthorhombic olivine-type lithium iron phosphate cathode material was prepared by using a so...

Embodiment 2

[0033] LiCH 3 COO, FeC 2 o 4 2H 2 O and (NH 4 ) 2 HPO 4 Weigh 20g according to the stoichiometric ratio of Li:Fe:P=1:1:1, mix with 3.5g polyvinyl alcohol (PVA) evenly, and ball mill on planetary ball mill for 8h; in Ar atmosphere, the precursor Pre-fired at 400°C for 6 hours, and ball milled for 5 hours after natural cooling to obtain powder materials; transfer to a tube furnace to heat at a heating rate of 10°C / min, and use toluene as an organic precursor to coat carbon on the surface of the material by chemical vapor deposition , the gas flow rate is 100mL / min, and it is calcined at a constant temperature of 700°C for 24h. Lithium-ion battery lithium iron phosphate (LiFePO 4 ) positive electrode material. The average particle size of the material is measured to be 1~10μm, and the tap density is 1.58g / cm 3 .

[0034] The XRD pattern of the product is shown in the curve b in Figure 1. It can be seen from the figure that the product has no impurities and is a single o...

Embodiment 3

[0036] LiOH·H 2 O, FePO 4 4H 2 Weigh 30g of O according to the stoichiometric ratio of Li:Fe(P)=1:1, mix it with 6g of sucrose evenly, and mill it on a planetary ball mill for 8 hours; 2 In the atmosphere, the precursor was pre-fired at 300 °C for 10 h, and after natural cooling, ball milled for 6 h to obtain the powder material; it was transferred to a tube furnace and heated at a heating rate of 15 °C / min, and biphenyl was used as an organic precursor. Chemical vapor deposition method Carbon coating is carried out on the surface of the material, the gas flow rate is 200mL / min, and it is calcined at a constant temperature of 750°C for 48h. Lithium-ion battery lithium iron phosphate (LiFePO 4 ) positive electrode material. The average particle size of the material is measured to be 3~8μm, and the tap density is 1.42g / cm 3 .

[0037] The XRD pattern of the product is shown in the curve c in Fig. 1. It can be seen from the figure that the product has no impurities and is a...

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Abstract

The invention relates to a method for synthesizing LiFePO4 / C material by chemical vapor deposition supporting the solid phase reaction method, namely, the method for preparing carbon coating lithium iron battery anode material, belonging to the Li-ion battery material preparation art technical field. The characteristics of the method for synthesizing LiFePO4 / C materials by solid phase and auxiliary chemical vapor deposition are that auxiliary chemical vapor deposition supporting the solid phase reaction method is adopted to synthesize the carbon coating phosphate lithium iron, namely, the LiFePO4 / C material. In the method for synthesizing LiFePO4 / C material by chemical vapor deposition supporting the solid phase reaction method, a precursor comprising raw materials of lithium, iron and phosphor is adopted to prepare the carbon coating phosphate lithium iron after being blended, grinded by a globe mill, treated by preheating and calcined as well as vapor deposition. The method for synthesizing LiFePO4 / C material by chemical vapor deposition supporting the solid phase reaction method has the advantages that the chemical composition, carbon contents and grain size of LiFePO4 can be controlled effectively; the Li-ion battery anode material prepared has sound conductive performance and can improve the charge-discharge rate and cycling performance of the material.

Description

technical field [0001] The invention relates to a chemical vapor deposition-assisted solid-phase method for synthesizing LiFePO 4 The method of / C material, that is, the method of preparing carbon-coated lithium iron phosphate battery cathode material. The invention belongs to the technical field of lithium ion battery material preparation technology. Background technique [0002] Energy is closely related to the survival and development of human society. Sustainable development and a harmonious society are the common aspiration and goal of all mankind. Chemical power is a device that directly converts chemical energy into electrical energy. With the rapid development of electronic technology and information industry, it plays an increasingly important role in people's daily life, industry and national defense. With the continuous advancement of technology, mobile communications, portable electrical appliances, and electric tools are increasingly becoming smaller and ligh...

Claims

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Application Information

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IPC IPC(8): H01M4/58H01M4/04C01B25/45C23C16/00B22F1/02
CPCY02E60/10
Inventor 赵兵焦正吴明红蒋永仲明阳施文彦吴文静周诗情庄华
Owner SHANGHAI CHIYUAN NEW MATERIAL TECH
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