Positive pole lithium iron phosphate/carbon composite material for low-temperature battery and preparation method of composite material

A carbon composite material, lithium iron phosphate technology, applied in battery electrodes, phosphorus compounds, chemical instruments and methods, etc., can solve the problem of poor low-temperature discharge performance of lithium iron phosphate nanocrystals, high reaction equipment requirements, and increased cost pressures, etc. problems, to achieve the effect of shortening the high temperature calcination time, simplifying the synthesis process, reducing energy consumption and production costs

Inactive Publication Date: 2015-03-04
CHENGDU SCI & TECH DEV CENT CHINA ACAD OF ENG PHYSICS
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Problems solved by technology

The general steps of the mechanical method are to mix the basic raw materials and perform high-energy ball milling once or twice to increase the reaction area and then perform long-term calcination, as described in patent application numbers 201210155024.5 and 201310504706.7. The disadvantage is that a large amount of grinding equipment is required and can consumes a lot
The commonly used liquid-phase synthesis method is hydrothermal or

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  • Positive pole lithium iron phosphate/carbon composite material for low-temperature battery and preparation method of composite material
  • Positive pole lithium iron phosphate/carbon composite material for low-temperature battery and preparation method of composite material
  • Positive pole lithium iron phosphate/carbon composite material for low-temperature battery and preparation method of composite material

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preparation example Construction

[0025] The preparation method of the positive electrode material lithium iron phosphate / carbon composite material for low-temperature batteries in this embodiment is characterized in that it includes the following steps:

[0026] a. Divalent iron compound, lithium compound, phosphorus compound and carbon source are respectively dispersed in deionized water to form a solution or suspension with a concentration of 0.5-1.5mol / L; the divalent iron compound in molar ratio: lithium compound : phosphorus compound=0.98~1:1:1~1.02; the carbon source is 1%~10% of the quality of the lithium iron phosphate cathode material obtained from the basic raw material;

[0027] b. Add the solution or suspension obtained in step a to a certain volume of liquid-phase reducing agent to form a mixed solution and then reflux at a certain temperature for 4-16 hours at normal pressure, and then separate the solid and liquid to obtain the lithium iron phosphate precursor powder ;

[0028] c. Place the li...

Embodiment 1

[0040]Weigh the basic raw materials ferrous phosphate, lithium hydroxide and phosphoric acid according to the ratio of element molar ratio Fe:Li:P=1.0:1.0:1.0, and weigh the amount of carbon source citric acid as 10% of the obtained lithium iron phosphate cathode material The above-mentioned raw materials are respectively dispersed in deionized water, the concentration of ferrous phosphate suspension is 1.5mol / L, and the concentration of lithium hydroxide, phosphoric acid and citric acid solution is respectively 1.0mol / L, 0.5mol / L and 0.5mol / L L, the volume ratio of the sum of the volume of the suspension and the solution to the liquid-phase reducing agent triethylene glycol is 1.0; add it to the liquid-phase reducing agent in the following order, and stir while adding: ferrous phosphate suspension-phosphoric acid solution -Citric acid solution-Lithium hydroxide solution, after mixing evenly, reflux reaction at 250°C for 8 hours, after cooling, perform centrifugation to achieve...

Embodiment 2

[0043] According to the ratio of element molar ratio Fe:Li:P=0.98:1.0:1.0, the basic raw material ferrous carbonate, lithium acetate and ammonium dihydrogen phosphate are weighed, and the amount of carbon source glucose is 10% of the obtained lithium iron phosphate positive electrode material. %; Disperse the above raw materials in deionized water respectively, the concentration of the ferrous carbonate suspension is 1.2mol / L, the concentrations of lithium acetate, ammonium dihydrogen phosphate and glucose solution are respectively 0.5mol / L, 1.0mol / L and 1.0 mol / L, the volume ratio of the sum of the volumes of the suspension and the solution to the liquid-phase reducing agent diethylene glycol is 0.5; add it to the liquid-phase reducing agent in the following order, and stir while adding: ferrous carbonate suspension- Ammonium dihydrogen phosphate solution-glucose solution-lithium acetate solution, after mixing evenly, reflux at 240°C for 12 hours, and then perform centrifugati...

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Abstract

The invention discloses a preparation method of a positive pole lithium iron phosphate/carbon composite material for a low-temperature battery. The preparation method comprises the following steps: by adopting a ferrous compound as a raw material, and weighing the ferrous compound, a lithium compound and a phosphorus compound according to the mole ratio of Fe:Li:P=(0.98-1):(1-1.02):1; respectively dissolving or dispersing in deionized water; adding to a liquid-phase reducing agent with moderate volume according to a certain sequence; carrying out reflux reaction at specific temperature; carrying out solid-liquid separation to obtain lithium iron phosphate precursor; then calcining under the protection of inert gas to prepare the LiFePO4/C composite positive pole material. Compared with other methods, the preparation method disclosed by the invention has the advantages of simple process equipment, moderation in condition, completeness in precursor crystallization, great shortening of high-temperature calcination time, great reduction of energy consumption, fine lithium iron phosphate particle diameter and more excellent normal-temperature discharge property and low-temperature charge-discharge property.

Description

technical field [0001] The invention relates to the field of cathode materials for lithium ion batteries, in particular to a method for preparing a cathode material lithium iron phosphate / carbon composite material for low-temperature lithium ion batteries. technical background [0002] With the emergence of new materials and improvements in battery design technology, the application range of lithium-ion batteries continues to expand. The civilian field has expanded from the information industry to energy transportation. In the field of national defense and military affairs, lithium-ion batteries cover many arms such as land, sea, air, and space. Among them, when military equipment needs to work in cold regions (such as below -40°C), the low-temperature electrochemical performance of lithium-ion batteries is extremely high. However, the charge-discharge performance of lithium-ion batteries in low-temperature environments below -20°C decays significantly. , greatly restricti...

Claims

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Application Information

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IPC IPC(8): H01M4/58H01M4/62C01B25/45
CPCC01B25/45H01M4/5825H01M4/587Y02E60/10
Inventor 刘昊李绍敏梅军刘焕明
Owner CHENGDU SCI & TECH DEV CENT CHINA ACAD OF ENG PHYSICS
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