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Method for improving heavy-current discharge performance of iron phosphate lithium

A high-current discharge, lithium iron phosphate technology, applied in battery electrodes, chemical instruments and methods, circuits, etc., can solve the problems of poor high-current discharge performance, complicated preparation process, and difficulty in industrialization, so as to improve ionic conductivity, The effect of low calcination temperature and low production cost

Inactive Publication Date: 2006-07-19
CENT SOUTH UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The sol-gel method can make the raw materials evenly mixed at the molecular level, and the batch stability of the product is easy to control, but the high-current discharge performance is poor, the preparation process is complicated, the conditions are harsh, and the cost is high, so it is difficult to industrialize

Method used

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  • Method for improving heavy-current discharge performance of iron phosphate lithium
  • Method for improving heavy-current discharge performance of iron phosphate lithium
  • Method for improving heavy-current discharge performance of iron phosphate lithium

Examples

Experimental program
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Effect test

Embodiment 1

[0021] Example 1 After fully stirring and mixing an equal volume of 0.1 mol / L ferrous chloride, chromium sulfate mixed solution (the molar ratio of iron and chromium elements is 95:5) and 0.1 mol / L phosphoric acid, add lithium hydroxide to control the pH value is 3.5, then add sodium peroxide to obtain a suspension, the suspension stays in a strongly stirred reactor for 6 hours, then filters and washes, and the obtained filter cake (precursor) is baked at 120° C. for 12 hours. Mix the dried precursor, carbon gel and lithium acetate according to the stoichiometric ratio (the carbon gel is calculated according to the carbon content), and at the same time ensure that the excess carbon gel is 1%, after ball milling for 30 minutes, then put the mixture into the reduction furnace , heated to 500°C, 600°C, 700°C, and 800°C at a heating rate of 2°C / min and held for 20 hours. The obtained material is analyzed by X-ray diffraction as an olivine structure, and the space group is Pnma, wh...

Embodiment 2

[0023] Example 2 After fully stirring and mixing equal volumes of 0.1 mol / L ferrous sulfate and nickel sulfate mixed solution (the molar ratio of iron and nickel elements is 95:5) and 0.1 mol / L sodium dihydrogen phosphate, add ammonia water to control the pH The value is 3.5, then add hydrogen peroxide to obtain a suspension, the suspension stays in a strongly stirred reactor for 6 hours, then filters and washes, and the obtained filter cake (precursor) is baked at 120°C for 12 hours. Mix the dried precursor, carbon black and lithium hydroxide according to the stoichiometric ratio, and at the same time ensure that the excess of carbon black is 1%, after ball milling for 30 minutes, then put the mixture into the reduction furnace, and pass N 2 Gas protection, heating to 600°C at a heating rate of 2°C / min and holding for 10h, 20h and 30h respectively. The obtained material is analyzed by X-ray diffraction as an olivine structure, and the space group is Pnma, which is LiFePO 4 S...

Embodiment 3

[0025]Example 3 Mix equal volumes of 0.1mol / L ferrous acetate and manganese sulfate mixed solution (the molar ratios of iron and manganese elements are respectively 99:1, 97:3, 95:5, 90:10) and 0.1mol / L After ammonium dihydrogen phosphate is fully stirred and mixed, lithium hydroxide is added to control the pH value to 3.5, and then sodium peroxide is added to obtain a suspension, which stays in a strongly stirred reactor for 6 hours, then filtered and washed to obtain The filter cake (precursor) was baked at 120°C for 12 hours. Mix the dried precursor, acetylene black and lithium carbonate according to stoichiometry, and at the same time ensure that the excess of acetylene black is 1%, after ball milling for 30 minutes, then put the mixture into the reduction furnace, and pass through Ar gas protection, at 2°C / min The heating rate is heated to 600 ° C and kept for 20 hours. The obtained material is analyzed by X-ray diffraction as an olivine structure, and the space group is...

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Abstract

The invention relates to a method for preparing the lithium anode material which is characterized in that: mixing the bivalence iron compound, doping metallic compound, phosphor compound and oxidant, to be reacted in the mixing reactor with temperature of 20-100Deg. C and the pH =1-8 for 0.5-24 hours; drying in 30-160Deg. C; mixing attained leading element, the lithium compound and the deoxidize carbon; heating in non-oxygenation condition to 400-800Deg. C in the temperature increase speed of 1-40Deg. C / min to be calcined in constant temperature for 2-35 hours; decreasing the temperature in the speed of 1-20Deg. C / min to attain the final product. The invention uses the carbon heating to deoxidize the trivalent iron which can solve the oxygenation problem of ferrous iron ion; and uses the mixed ferric phosphate and doping phosphate as leading elements to solve the uniform mixing problem of doping elements and improve the conductivity of material to improve the big current (o.8C) discharge / charge property, with short preparation time, easy control, lower energy consumption and lower cost.

Description

technical field [0001] The invention belongs to the preparation method of lithium ion cathode material in the field of materials. Background technique [0002] LiFePO with olivine structure 4 It can reversibly intercalate and deintercalate lithium ions, and FePO obtained by delithiation 4 The volume is only 6.81% less than the original volume, so it has good cycle performance. At the same time LiFePO 4 The material has the advantages of non-toxicity, environmental friendliness, rich source of raw materials, high specific capacity (theoretical capacity is 170mAh / g, energy density is 550Wh / Kg), and high temperature stability. But the following shortcomings hinder its practical application: (1) Fe in the synthesis 2+ easily oxidized to Fe 3+ , it is not easy to obtain single-phase LiFePO 4 ; (2) lithium ions in LiFePO 4 Diffusion is difficult in medium, resulting in low utilization of active materials; (3) LiFePO 4 The electronic conductivity of the battery is low, whic...

Claims

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Application Information

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IPC IPC(8): H01M4/04H01M4/58H01M4/48C01D15/00C01B25/00C01G1/02C01G49/00
CPCY02E60/10
Inventor 朱炳权李新海王志兴郭华军彭文杰胡启阳张云河
Owner CENT SOUTH UNIV
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