This application claims the priority of Chinese Patent Application No. 202111175470.8, filed with the China National Intellectual Property Administration on Oct. 9, 2021, and titled with “PREPARATION METHOD OF HIGH-RATE LITHIUM IRON PHOSPHATE POSITIVE ELECTRODE MATERIAL”, which is hereby incorporated by reference.
The present disclosure belongs to the field of lithium batteries, and relates to the production of positive electrode materials for lithium ion batteries, in particular to a method for producing high-rate lithium iron phosphate positive electrode material.
Although the traditional lead-acid battery has mature technology and low cost, it has low mass and volume energy density, short cycle life, and a risk of lead pollution in the industrial chain. Polyanion lithium iron phosphate represented by lithium iron phosphate as the positive electrode material for lithium ion battery has received extensive attention due to its advantages of high theoretical capacity, good thermal stability, good cycle capability, stable structure, environmental friendliness, etc., especially in the field of power batteries and start-stop power supplies. As the technology of lithium iron phosphate becomes increasingly mature, the application of lithium iron phosphate to replace lead-acid batteries in the field of start-stop power supply is becoming increasingly extensive.
At present, the synthesis methods for producing lithium iron phosphate positive electrode materials are mainly divided into the following five categories, namely high-temperature solid-phase method, carbothermic reduction method, microwave synthesis method, sol-gel method and hydrothermal/solvothermal method. The hydrothermal/solvothermal method and high-temperature solid-phase method are currently the main methods used to synthesize lithium iron phosphate. The lithium iron phosphate material produced by the hydrothermal/solvothermal method has the advantages of complete crystalline structure, no impurity peak, uniform particle size, even carbon coating on the particle surface, etc. However, the hydrothermal/solvothermal method has complicated production process, high consumption of lithium source, high cost, and a low reaction temperature in the production of lithium iron phosphate, which easily causes antisite defects in the material lattice.
The high-temperature solid-phase method comprises fully grinding a lithium source, an iron source, a phosphorus source, and a carbon source with pure water according to a certain ratio, subjecting the mixture to high temperature spray pyrolysis to obtain a pale yellow precursor powder, and reacting the obtained powder at a high temperature under a protective atmosphere for a period of time to obtain well-crystallized lithium iron phosphate. The method has the advantages of low cost, simple process route, good product stability, even carbon coating, and easy large-scale industrial production, but has the disadvantages of large primary particle, uneven particle size, long diffusion distance of lithium ion, and low diffusion coefficient, which seriously restrict its application in high-power start-stop power supplies. Therefore, researching and solving the above problems is the direction of further research on the high-temperature solid-phase method.
Mainly to solve the above problem of easily causing large primary particles and uneven particles in the production of lithium iron phosphate positive electrode material by high-temperature solid-phase method, the present disclosure provides a novel high-rate lithium iron phosphate positive electrode material and a production method thereof.
The present disclosure is realized through the following solution:
In the method for producing a lithium iron phosphate positive electrode material, the precursor is sintered at a high temperature of 650-700° C. under the protection of a nitrogen atmosphere. In the following preferred embodiments of the present disclosure, the conditions such as the excess coefficient of the lithium source, the type of the carbon source, the particle size D50 after the sand grinding, and the temperature of the high-temperature sintering are specifically defined.
The method for producing a lithium iron phosphate positive electrode material comprises specific steps of:
The present disclosure has the following beneficial effects:
The material prepared by the present disclosure has a complete crystalline structure, no impurity peak, good discharge capacity and good cycle capability.
The technical solutions of the present disclosure will be clearly and completely described below in conjunction with the examples of the present disclosure. It is apparent that the described examples are only a part of the embodiments of the present disclosure, rather than all the embodiments. Based on the examples of the present disclosure, all the other examples obtained by those of ordinary skill in the art without any creative work shall fall into the scope of the present disclosure.
The high-rate lithium iron phosphate positive electrode material of the present disclosure has spherical-like morphology, and the primary particle thereof has a particle size of 100 nm. The specific production method comprises:
In the present disclosure, a lithium iron phosphate precursor with spherical-like morphology is produced using a high-temperature solid-phase method, then the precursor is sintered to obtain a lithium iron phosphate positive electrode material with spherical-like morphology, wherein the primary particle thereof has a particle size of 100 nm. The produced material has a complete crystalline structure, no impurity peaks, good discharge capacity and good cycle capability.
First, 25 g of anhydrous iron phosphate, 6.3 g of lithium carbonate, 2.64 g of glucose, 0.32 g of PEG2000, and 0.25 g of titanium dioxide were weighed, and the above raw materials were dispersed in 5.3 g of deionized water. The resulting mixture was ball milled for 2 h, and then transferred to sand grinding, so that the particle size D50 after the sand grinding was controlled to be 100-200 nm. The iron source, lithium source, carbon source, metal ion doping agent and other raw materials were fully mixed evenly, and then the mixture was centrifugally spray-dried to obtain a pale yellow precursor powder. The precursor was placed in a graphite saggar, and sintered at a high temperature of 650-700° C. under the protection of nitrogen atmosphere for 18-20 hours, and the sintered material was naturally cooled. The sintered material was pulverized by a jet mill, and iron was removed from the pulverized material to obtain a high-rate lithium iron phosphate positive electrode material.
First, 25 g of anhydrous iron phosphate, 6.3 g of lithium carbonate, 3.8 g of sucrose, 0.78 g of PEG2000, and 0.25 g of titanium dioxide were weighed, and the above raw materials were dispersed in 5.3 g of deionized water. The resulting mixture was ball milled for 2 h, and then transferred to sand grinding, so that the particle size D50 after the sand grinding was controlled to be 100-200 nm. The iron source, lithium source, carbon source, metal ion doping agent and other raw materials were fully mixed evenly, and then the mixture was centrifugally spray-dried to obtain a pale yellow precursor powder. The precursor was placed in a graphite saggar, and sintered at a high temperature of 650-700° C. under the protection of nitrogen atmosphere for 18-20 hours, and the sintered material was naturally cooled. The sintered material was pulverized by a jet mill, and iron was removed from the pulverized material to obtain a high-rate lithium iron phosphate positive electrode material.
First, 25 g of anhydrous iron phosphate, 6.3 g of lithium carbonate, 5.68 g of citric acid, and 0.13 g of titanium dioxide were weighed, and the above raw materials were dispersed in 5.3 g of deionized water. The resulting mixture was ball milled for 2 h, and then transferred to sand grinding, so that the particle size D50 after the sand grinding was controlled to be 100-200 nm. The iron source, lithium source, carbon source, metal ion doping agent and other raw materials were fully mixed evenly, and then the mixture was centrifugally spray-dried to obtain a pale yellow precursor powder. The precursor was placed in a graphite saggar, and sintered at a high temperature of 650-700° C. under the protection of nitrogen atmosphere for 18-20 hours, and the sintered material was naturally cooled. The sintered material was pulverized by a jet mill, and iron was removed from the pulverized material to obtain a high-rate lithium iron phosphate positive electrode material.
First, 25 g of anhydrous iron phosphate, 6.3 g of lithium carbonate, 5.68 g of glucose, 0.32 g of PEG2000, and 0.31 g of zirconium dioxide were weighed, and the above raw materials were dispersed in 5.3 g of deionized water. The resulting mixture was ball milled for 2 h, and then transferred to sand grinding, so that the particle size D50 after the sand grinding was controlled to be 100-200 nm. The iron source, lithium source, carbon source, metal ion doping agent and other raw materials were fully mixed evenly, and then the mixture was centrifugally spray-dried to obtain a pale yellow precursor powder. The precursor was placed in a graphite saggar, and sintered at a high temperature of 650-700° C. under the protection of nitrogen atmosphere for 18-20 hours, and the sintered material was naturally cooled. The sintered material was pulverized by a jet mill, and iron was removed from the pulverized material to obtain a high-rate lithium iron phosphate positive electrode material.
The lithium iron phosphate material prepared in Example 1 was characterized by a Japanese Rigaku X-ray powder diffractometer (XRD). The results are shown in
The lithium iron phosphate positive electrode material prepared in Example 1 was mixed with a conductive carbon powder and a PVDF binding agent in a mass ratio of 90:5:5, then the mixture was homogenized and coated on an aluminum foil. The coated foil was dried at 100° C., and pressed by a pair-roll mill, and an electrode piece with a diameter of 14 mm was prepared by a sheet punching machine. The electrode piece was weighed, and the mass of the aluminum foil was deducted from the mass of the electrode piece to obtain the mass of the active material. The electrode piece was dried, and assembled to a CR2032 button half-cell in the order of negative electrode shell, lithium sheet, electrolyte, diaphragm, electrolyte, electrode piece, gasket, shrapnel, and positive electrode shell in a UNlab inert gas glove box of MBRAUN, Germany. The CR2032 button half-cell was tested for electrochemical performance within a voltage range of 2.0-3.9 V by Wuhan Land Electronics CT2001A battery test system. The test results are shown in
The above are only the preferred embodiments of the present disclosure. It should be noted that for those of ordinary skill in the art, several improvements and modifications can be made without departing from the principles of the present disclosure, which should also be regarded as the protection scope of the present disclosure.
Number | Date | Country | Kind |
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202111175470.8 | Oct 2021 | CN | national |
Filing Document | Filing Date | Country | Kind |
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PCT/CN2022/104544 | 7/8/2022 | WO |