Method for preparing anode material of lithium ion battery in series of phosphate of olivine type

A lithium-ion battery, olivine-type technology, applied in battery electrodes, chemical instruments and methods, circuits, etc., can solve the problem of difficulty in preparing mixed uniform metal ion-doped lithium iron phosphate cathode materials, affecting the energy density of cathode materials, and being unable to suppress Oxidation and other problems, to achieve uniform distribution of chemical components, good cycle performance, easy to control the effect of operation

Inactive Publication Date: 2007-10-10
CENT SOUTH UNIV
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Problems solved by technology

Adding carbon can not only refine the particles and improve the electrical conductivity of the material, but also act as a reducing agent to suppress Fe 2+ Oxidation, but due to the low density of carbon, it will inevitably affect the energy density of the positive electrode material
Adding metals such as ultrafine silver powder or copper powder can improve the conductivity of the material without affecting the energy density of the material, but it cannot inhibit the Fe 2+ Oxidation, and the cost is higher
Optimizing the synthesis process and adding conductive materials can only improve the apparent conductivity of the material. In order to improve the intrinsic conductivity of the material, LiFePO 4 Doping a small amount of metal ions on Li and Fe sites is a feasible method. The current method of doping metal ions is to directly mix the main element compound and the dopant element compound with a ball mill, and then perform high-temperature combustion synthesis. This method It is difficult to prepare uniformly mixed metal ion-doped lithium iron phosphate cathode materials

Method used

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  • Method for preparing anode material of lithium ion battery in series of phosphate of olivine type
  • Method for preparing anode material of lithium ion battery in series of phosphate of olivine type
  • Method for preparing anode material of lithium ion battery in series of phosphate of olivine type

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Effect test

Embodiment 1

[0027] Mix 1.0mol / L oxalic acid solution with 0.8mol / L ferrous sulfate and nickel sulfate mixed solution (wherein the molar ratio of iron to nickel is: N Fe2+ :N Ni2+ = 4:1) mixed, controlled reaction temperature 50°C, reaction pH value 2.0, obtained compound oxalate precipitate, filtered, washed and dried, mixed with stoichiometric ratio NH 4 h 2 PO 4 and Li 2 CO 3 , adding an appropriate amount of absolute ethanol, milling on a ball mill for 5 hours, and drying to obtain a sample. The sample was transferred to a closed reaction furnace, under the protection of argon atmosphere, decomposed at 380°C for 5h, heated to 600°C, burned for 20h, and then cooled to room temperature with the furnace. The X-ray diffraction analysis of the obtained product shows that it is an orthorhombic olivine-type lithium iron phosphate with a complete crystal structure.

Embodiment 2

[0029] The total concentration (Fe+Ni) is 0.8mol / L, different Fe 2+ with you 2+ Mix the molar ratio mixed solution with 1.2mol / L oxalic acid solution, the reaction pH value is 2.0, and the reaction temperature is 50°C. After the reaction precipitate is filtered, washed and dried, an appropriate amount of NH is added according to the stoichiometric ratio. 4 h 2 PO 4 , Li 2 CO 3, ball milled in ethanol medium for 5h. After the ball-milled mixed sample was dried and screened, it was transferred to a closed reaction furnace, under the protection of an argon atmosphere, it was thermally decomposed at 380°C for 5h, heated to 600°C for 20h, and then cooled to room temperature with the furnace. The obtained product was assembled into an experimental battery, and its initial discharge specific capacity was measured by constant current charge and discharge technology, and the constant current discharge was carried out at a discharge current of 0.1C. Their initial discharge specific...

Embodiment 3

[0032] The total concentration (Fe+Ni) is 0.8mol / L, Fe 2+ with you 2+ The molar ratio is: N Fe2+ :N Ni2+ = The mixed solution of 0.95:0.05 is mixed with 1.2mol / L oxalic acid solution, the reaction pH value is controlled to 2.0, and the reaction temperature is 50°C. After the reaction precipitate is filtered, washed and dried, an appropriate amount of NH is added according to the stoichiometric ratio. 4 h 2 PO 4 , Li 2 CO 3 , ball milled in ethanol medium for 5h. After the ball-milled mixed sample was dried and sieved, it was transferred to a closed reaction furnace, under the protection of argon atmosphere, it was thermally decomposed at different pretreatment temperatures for 5 hours, heated to 600 ° C for 20 hours, and then cooled to room temperature with the furnace. The obtained product was assembled into an experimental battery, and its initial discharge specific capacity was measured by constant current charge and discharge technology, and the constant current dis...

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Abstract

This invention relates to a method for preparing olivine-type phosphate-series lithium ion battery anode material. The method comprises: mixing one or more of ferrous salt solution, cobalt salt solution and manganese salt solution with oxalic acid or oxalate (precipitating agent) aqueous solution to obtain composite oxalate precursor, uniformly mixing with lithium source and phosphorus source by ball milling, and reacting in inert or weak-reductive atmosphere to obtain olivine-type phosphate-series lithium ion battery anode material. The method utilizes co-precipitation method for metal ion doping, and realizes molecular level uniform mixing among different ions. The obtained olivine-type phosphate-series lithium ion battery anode material has uniform chemical and physical compositions. The average particle size can be controlled within 0.3-10 mu.m. The first charge and discharge cycle specific capacity can reach 150 mAh/g at 0.1 C rate and room temperature. The livine-type phosphate-series lithium ion battery anode material has such advantages as high cycle performance and high charge/discharge performance.

Description

technical field [0001] The invention relates to a preparation method of an olivine-type phosphate series lithium-ion battery positive electrode material doped with metal ions by a co-precipitation method, and belongs to the technical field of material preparation. Background technique [0002] In recent years, the research and development of lithium-ion batteries have made gratifying achievements, especially the improvement of the performance of the negative electrode and the development of the electrolyte system have achieved great results, but the research on the cathode materials of lithium-ion batteries appears to be relatively lagging behind, which has become a constraint for lithium-ion batteries. The bottleneck of battery market and application expansion. Lithium cobalt oxide, lithium nickel oxide, lithium nickel cobalt composite oxide, lithium manganese oxide, lithium vanadate and other positive electrode materials have always been a hot spot in the field of positive...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01B25/45H01M4/58
CPCY02E60/10
Inventor 戴曦张传福唐红辉杨平邬建辉
Owner CENT SOUTH UNIV
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