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Lithium ferrous silicate anode material coated with crystalline carbon and preparation method thereof

A technology of lithium ferrous silicate and positive electrode materials, which is applied in the direction of battery electrodes, structural parts, electrical components, etc., can solve the problems of reducing the volumetric energy density of positive electrode materials, low tap density of products, and poor particle contact performance. Improved electrochemical performance, fine grain size, and high powder purity

Inactive Publication Date: 2011-10-05
TIANJIN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

Although Chinese patent 101841016A uses crystalline carbon nanotubes as a carbon source to obtain crystalline carbon-coated Li 2 FeSiO 4 powder, but because carbon nanotubes and precursors are only mechanically mixed, the tap density of the product is not high, carbon and Li 2 FeSiO 4 The contact performance of the particles is poor, which reduces the volume energy density of the positive electrode material. At the same time, the product obtained by the solid-state reaction method contains more impurities, which reduces the specific capacity of the material.

Method used

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  • Lithium ferrous silicate anode material coated with crystalline carbon and preparation method thereof
  • Lithium ferrous silicate anode material coated with crystalline carbon and preparation method thereof
  • Lithium ferrous silicate anode material coated with crystalline carbon and preparation method thereof

Examples

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Embodiment 1

[0023] Using lithium acetate dihydrate, ferric nitrate, and ethyl orthosilicate as raw materials, weigh the corresponding substances according to the molar ratio of the substances, so that the molar ratio of Li:Fe:Si is 2:1:1, and measure 1.8ml of ethyl orthosilicate Add the ester to 15ml of ethanol and keep stirring, add 0.32ml of acetic acid dropwise, accurately weigh 1.640g of lithium acetate and add it to the above mixed solution, add 3.256g of ferric nitrate after dissolving, make 1.057g of ascorbic acid into a saturated aqueous solution, and add it dropwise to Among the above mixed solutions, the mixed solution was transferred to a reaction kettle and reacted at 120° C. for 20 hours to obtain a gel mixture, which was then dried in a drying oven at 60° C. to obtain a xerogel. Grind the xerogel, press into tablets, in N 2 Under the protection of the atmosphere, it was calcined at 650° C. for 10 h to obtain carbon-coated lithium ferrous silicate powder. Li 2 FeSiO 4 The ...

Embodiment 2

[0025] Using lithium acetate, ferric nitrate, and ethyl orthosilicate as raw materials, weigh the corresponding substances according to the molar ratio of the substances, so that the molar ratio of Li:Fe:Si is 2:1:1, measure 1.8ml of ethyl orthosilicate and add Add 0.32ml of acetic acid dropwise to 10ml of ethanol with constant stirring, accurately weigh 1.640g of lithium acetate and add it to the above mixture, add 3.256g of ferric nitrate after dissolving, make 0.700g of ascorbic acid into a saturated aqueous solution, and add dropwise to the above mixture In the solution, the mixed solution was transferred to a reaction kettle, and reacted at 120° C. for 5 hours to obtain a gel mixture, which was then dried in a drying oven at 60° C. to obtain a xerogel. Grind the xerogel, press into tablets, in N 2 Under the protection of the atmosphere, it was calcined at 650° C. for 7 hours to obtain carbon-coated lithium ferrous silicate powder. Synthetic powder Li 2 FeSiO 4 / C micro...

Embodiment 3

[0027] Using lithium acetate dihydrate, ferric nitrate, and ethyl orthosilicate as raw materials, weigh the corresponding substances according to the molar ratio of the substances, so that the molar ratio of Li:Fe:Si is 2:1:1, and measure 1.8ml of ethyl orthosilicate Add the ester to 18ml of ethanol and keep stirring, add 0.32ml of acetic acid dropwise, accurately weigh 1.640g of lithium acetate and add it to the above mixed solution, add 3.256g of ferric nitrate after dissolving, make 1.929g of ascorbic acid into a saturated aqueous solution, and add it dropwise to In the above mixed solution, the mixed solution was transferred to a reaction kettle and reacted at 180° C. for 5 hours to obtain a gel mixture, which was then dried in a drying oven at 60° C. to obtain a xerogel. Grind the xerogel, press into tablets, in N 2 Under the protection of the atmosphere, it was calcined at 750° C. for 10 h to obtain carbon-coated lithium ferrous silicate powder. Synthetic Li 2 FeSiO 4...

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Abstract

The invention relates to a high-purity lithium ferrous silicate anode material coated with crystalline carbon and a preparation method thereof. In the lithium ferrous silicate anode material coated with the crystalline carbon, the particle diameter of powder is 50-350 nm, and the initial discharge capacity of the anode material at the rate of C / 16 is 125.7-150.3 mAhg<-1>, the weight percent of carbon is 5-15 percent by weight; a Li2FeSiO4 precursor is prepared by using a sol-gel method which comprises the following steps of: with ascorbic acids as reductants and carbon sources, catalyzing by Fe(NO3)3 while reducing ferric ions to form crystalline graphite; and uniformly coating on surfaces of Li2FeSiO4 particles, thus, the electrical property of the Li2FeSiO4 / C anode material is effectively improved. Taking a carbon coating amount of 10.1 percent by weight as an example, the synthesized powder has high purity and is free of impurity phases; the initial discharge capacity at the rate of C / 16 is 150.3 mAhg<-1>; and after circulation forty times, the specific ratio is 137.2 mAhg<-1>, which embodies better rate performance and better circulation performance.

Description

technical field [0001] The invention relates to a high-purity crystalline carbon-coated lithium ferrous silicate positive electrode material and a preparation method, belonging to the technical field of energy material preparation. Background technique [0002] Due to its high energy density and flexible designability, rechargeable lithium-ion batteries have become the main components of portable devices such as mobile communications, notebook computers, and digital cameras. Compared with traditional lithium-ion batteries (such as LiMn 2 o 4 , LiCoO 2 and LiNiO 2 ), the polyanionic cathode material has been widely studied due to its advantages of safety, environmental protection and low cost. The more successful commercialization example is LiFePO 4 . Compared to LiFePO 4 , Li 2 FeSiO 4 Due to the stronger Si-O bond (relative to the P-O bond), Li 2 FeSiO 4 The structure is more stable, so it has higher chemical stability and electrochemical stability; in addition, ...

Claims

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Application Information

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IPC IPC(8): H01M4/1397H01M4/58
CPCY02E60/122Y02E60/12Y02E60/10
Inventor 蔡舒余其凯燕子鹏周幸
Owner TIANJIN UNIV
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