Method for assisted preparation of carbon composite lithium iron phosphate micro-nanometer powder through industrially modified starch

A technology of lithium iron phosphate and modified starch, applied in chemical instruments and methods, phosphorus compounds, inorganic chemistry, etc., can solve the problems of poor water solubility, cumbersome process, complicated preparation process, etc., and achieve cycle stability and rate performance Excellent, simple process steps, and uniform product scale

Inactive Publication Date: 2013-07-24
山东天润丰新能源科技有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

The powder performance is good, the capacity can reach 140mAh / g, but the particle size of the powder is uncontrollable and the distribution size is uneven, and the effect of surface modification (carbon composite, carbon encapsulation) is not ideal, making its performance unstable
Another example is that the patent of Publication No. CN1821062A discloses a method in which the precursor of lithium ferrous phosphate is obtained by solution evaporation with ferric phosphate, lithium acetate and reducing agent, and lithium ferrous phosphate is obtained through high-temperature heat treatment, and then mixed with glucose solution, Carbon-doped lithium iron phosphate is obtained by high-temperature calcination, the preparation process is complicated, the product yield is low, and the product particles are too large, the surface modification layer is uneven, and the battery performance is not ideal
In summary, the common problems in the current production of lithium iron phosphate are: cumbersome process, in-depth research on carbon-doped precursor materials, poor batch uniformity of products, small tap density, uneven surface modification, etc.
As a chemical raw material widely used in food, chemical, textile, building materials and other industries, starch has a wide variety, and can be subdivided and adjusted according to different needs. For the preparation of micro-nano inorganic materials, especially battery-grade lithium iron phosphate preparation, there is no research report
Among them, natural native starch has high viscosity, but its water solubility is extremely poor; cross-linked starch can significantly increase the viscosity and paste viscosity of native starch, but its water solubility is still not good; oxidized starch has good water solubility, but its viscosity Worse than native starch; hydroxyalkyl starch has good water solubility, high viscosity, and relatively high gelatinization temperature, but the price is higher

Method used

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  • Method for assisted preparation of carbon composite lithium iron phosphate micro-nanometer powder through industrially modified starch
  • Method for assisted preparation of carbon composite lithium iron phosphate micro-nanometer powder through industrially modified starch
  • Method for assisted preparation of carbon composite lithium iron phosphate micro-nanometer powder through industrially modified starch

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0030] Weigh 18.7g of 0.1mol ferric phosphate dihydrate and 4.06g of 0.055mol lithium carbonate, weigh 8.2g of soluble starch and 3g of glucose according to 60% of the mass ratio of ferric phosphate, and mix the above weighing with 100mL of pure water at one time, After two high-energy ball mills and one sand mill successively, each operation time is 2h. Then the resulting suspension is sprayed and granulated through a spray drying tower to obtain a surface modification precursor. Place the precursor evenly in a magnetic boat, preheat in a sintering furnace at 350°C for 4 hours in a nitrogen atmosphere, and then calcinate at 700°C for 10 hours to obtain surface-modified lithium iron phosphate nanopowders (such as figure 1 As shown in the curve a), the particle size distribution D50 of the product is between 8 and 15 μm, which is agglomerated spheres of nanoparticles.

Embodiment 2

[0032] Weigh 15.08g of 0.1mol anhydrous iron phosphate and 4.06g of 0.055mol lithium carbonate, weigh 6.6g of soluble starch, 1g of cross-linked hydroxypropyl tapioca starch and 3g of glucose according to 70% of the mass ratio of iron phosphate, and mix the above The weighed material was mixed with 100mL of pure water, and then passed through two high-energy ball mills and one sand mill successively, each operation time was 2h. Then the resulting suspension is sprayed and granulated through a spray drying tower to obtain a surface modification precursor. Place the precursor evenly in a magnetic boat, preheat in a sintering furnace at 350°C for 4 hours in a nitrogen atmosphere, and then calcinate at 700°C for 10 hours to obtain a surface-modified lithium iron phosphate powder (such as figure 1 As shown in the curve b in), the particle size distribution D50 of the product is between 5 and 10 μm, which is agglomerated spheres of nanoparticles.

Embodiment 3

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Abstract

The present invention discloses a production method for ferric phosphate nanometer powder with a characteristic of controllable particle size. In the prior art, battery grade ferric phosphate production processes commonly have disadvantages of large size, impure phase, complex process, high production cost and the like, and especially the phase carries a certain proportion of crystal water so as to directly cause instable phase, instable performances and the like of the lithium iron phosphate powder synthesized at the late stage. The synthesis process comprises: preparing a phosphate organic/pure water mixing base solution in a certain pH range, adding a plurality of additives, adding an iron salt solution at a constant temperature in a stepwise manner, adjusting the pH value of the solution during the adding process with a dropwise manner, carrying out constant temperature stirring for a certain time, carrying out suction filtration, washing and drying on the obtained product, and finally carrying out annealing for a certain time at a temperature of 300-600 DEG C to obtain the ferric phosphate nanometer powder. The ferric phosphate nanometer powder produced by the method has characteristics of controllable particle size, controllable components, simple process, low cost, high powder activity, easy production enlargement and high market competitiveness.

Description

technical field [0001] The invention belongs to the field of positive electrode materials for lithium-ion batteries, and in particular relates to a production method for preparing carbon-composite (surface-modified) lithium ferrous phosphate micro-nano powders assisted by industrial modified starch. Background technique [0002] The positive electrode material of lithium-ion battery is LiCoO 2 , LiNiO 2 , LiMn 2 o 4 、LiFePO 4 and ternary materials, etc. LiCoO 2 It is an early commercialized electrode material with a relatively complete preparation process and excellent overall performance, but it is polluted, expensive, and poor in overcharge resistance; LiNiO 2 The cost is lower and the capacity is higher, but the preparation is difficult, and the consistency and reproducibility of the material properties are poor; spinel LiMn 2 o 4 Low cost, good safety, but low capacity, poor cycle performance, used to partially replace other cathode materials; ternary materials h...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/58C01B25/45
CPCY02E60/10
Inventor 杨立山丁轶杨振三
Owner 山东天润丰新能源科技有限公司
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