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Preparation method of monodisperse lithium iron phosphate nanometer material and lithium-ion secondary battery

A lithium iron phosphate and nanomaterial technology, applied in secondary batteries, battery electrodes, circuits, etc., can solve the problems of poor conductivity and slow diffusion of lithium ions, and achieve small size, easy in-situ doping and carbon encapsulation, Stable dispersion effect

Active Publication Date: 2010-07-14
NINGBO INST OF MATERIALS TECH & ENG CHINESE ACADEMY OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The research found that the lithium iron phosphate material has a moderate working voltage (3.4V), a good platform, a theoretical capacity of 170mAh / g (the actual capacity can also be close to the theoretical capacity), excellent cycle performance, and low cost. Its high energy density and high safety The performance makes it have outstanding application prospects in power lithium-ion batteries, but its disadvantages are its poor conductivity and slow diffusion of lithium ions. Research has found that it can be improved by means of carbon materials, conductive polymer coatings, and metal ion doping. Its conductivity, but to increase its lithium ion diffusion rate, it is necessary to nanometerize the material to shorten the lithium ion diffusion channel, thereby improving the rate performance

Method used

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  • Preparation method of monodisperse lithium iron phosphate nanometer material and lithium-ion secondary battery
  • Preparation method of monodisperse lithium iron phosphate nanometer material and lithium-ion secondary battery
  • Preparation method of monodisperse lithium iron phosphate nanometer material and lithium-ion secondary battery

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preparation example Construction

[0026] The first step, preparation of lithium iron phosphate nanomaterials

[0027] Dissolve soluble lithium source compounds, ferrous source compounds, and phosphorus source compounds in water, add them to the organic solvent in sequence according to the specific molar ratio of materials and the order of addition, stir and mix, and control the volume ratio of the organic solvent to water in the mixed solution at 1 : between 3 and 3: 1, the concentration of each substance is controlled between 0.1 mol / L and 0.5 mol / L, the mixture is transferred to an autoclave, and reacted at 120°C to 230°C for 2 to 24 hours. The product undergoes processes such as washing and drying to obtain lithium iron phosphate nanomaterials.

[0028] The second step, preparation of lithium iron phosphate@carbon nanocomposite cathode active material

[0029] The carbon encapsulation process of lithium iron phosphate nanomaterials adopts the conventional carbon encapsulation process: in-situ encapsulation...

Embodiment 1

[0037] The first step, weigh 10.3ml of concentrated phosphoric acid with a mass fraction of 85%, add 150ml of water to make a 1M phosphoric acid solution, weigh 19.6g of lithium hydroxide and dissolve it in 450ml of water to make a 1M lithium hydroxide solution, weigh 41.7 g ferrous sulfate heptahydrate was dissolved in 300ml water to make 0.5M ferrous sulfate solution, first pour the phosphoric acid solution into 600ml polyethylene glycol 400 solvent, stir and mix well, then slowly add lithium hydroxide solution under stirring , Let it react for a period of time, then add the ferrous sulfate solution quickly, and continue to stir for a few minutes. Pour the mixed solution into a 2L magnetically driven stirred reactor with a lithium iron phosphate concentration of about 0.1M. Bubble argon or nitrogen for 5 minutes while stirring, then seal the reaction vessel, and react at 180° C. for 9 hours. After the reaction is completed and cooled, the collected product is washed and dri...

Embodiment 2

[0041] The first step, weigh 19.8g diammonium hydrogen phosphate, add 300ml water to make 0.5M diammonium hydrogen phosphate solution, weigh 6.6g lithium hydroxide and dissolve in 300ml water to make 0.5M lithium hydroxide solution, weigh Dissolve 29.81g of ferrous chloride tetrahydrate in 300ml of water to form a 0.5M ferrous sulfate solution. First, pour the diammonium hydrogen phosphate solution into 600ml of polyethylene glycol 400 solvent, stir and mix evenly, and slowly Add lithium hydroxide solution, let it react for a period of time, then add ferrous chloride solution quickly, and continue to stir for several minutes. The mixed solution was poured into a 2L magnetically driven stirred reactor, and argon or nitrogen gas was blown for 5 minutes while stirring, and then the reactor was sealed and reacted at a temperature of 180°C for 9 hours. After the reaction is completed and cooled, the collected product is washed and dried to obtain a lithium iron phosphate nanomateri...

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Abstract

The invention relates to a preparation method of a monodisperse lithium iron phosphate nanometer material, which is characterized by comprising the following steps of: dissolving a soluble lithium source compound, a ferrous source compound, a phosphorus source compound, a dopping element compound, a carbon source compound, and the like into water or a mixed solvent of the water and an organic solvent; sequentially adding to the organic solvent for stirring and mixing according to specific material mole ratio and order, and keeping the volume ratio of the organic solvent to the water to be within a certain range; transferring a mixture to a high-pressure reaction still for heating treatment; and processing a product through a plurality of steps of washing, drying, carbon coating, ball-milling, mixing, annealing, and the like to obtain the lithium iron phosphate anode active material which has high multiplying power circulation and property. The invention also discloses a relevant lithium-ion secondary battery. By adopting a hydrothermal / solvothermal method and using soluble materials as reactants, the invention enables ions to be uniformly mixed in the synthesizing process, thereby obtaining better crystal forms and very pure phases and further enhancing the property of batteries.

Description

technical field [0001] The invention relates to a liquid-phase synthesis of a cathode nanometer material of a phosphate lithium ion battery and a high-performance lithium ion battery based on the material. Background technique [0002] With the gradual depletion of energy and the escalation of environmental degradation, people's demand for new green and efficient energy is becoming increasingly urgent. As a new energy source with a strong competitive advantage, lithium-ion batteries have received special attention. In addition to their wide application in existing small portable batteries, the development prospects of lithium-ion batteries in high-power and high-energy power batteries are even more impressive. people look forward to. Compared with traditional lead-acid batteries, Ni-Cd batteries, Ni-H and other batteries, lithium-ion batteries have high energy density, high average output voltage, high output power, good cycle performance, long service life, and wide operat...

Claims

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Application Information

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IPC IPC(8): H01M4/1397H01M10/0525
CPCY02E60/12Y02E60/122Y02E60/10
Inventor 刘兆平杨石榴周旭峰张建刚
Owner NINGBO INST OF MATERIALS TECH & ENG CHINESE ACADEMY OF SCI
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