A kind of precursor and lithium manganese iron phosphate and its preparation method and application

A technology of precursors and iron salts, applied in the field of precursors, can solve the problems of poor rate and cycle performance, low discharge capacity and first efficiency of lithium manganese iron phosphate

Active Publication Date: 2018-12-21
BYD CO LTD
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] The invention solves the technical problems of low discharge capacity and initial efficiency, poor rate and cycle performance of lithium manganese iron phosphate prepared in the prior art, and provides a new precursor, a preparation method of the precursor, a phosphoric acid Preparation method of lithium iron manganese, lithium iron manganese phosphate prepared by the method, and application of said lithium iron manganese phosphate as positive electrode active material

Method used

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  • A kind of precursor and lithium manganese iron phosphate and its preparation method and application
  • A kind of precursor and lithium manganese iron phosphate and its preparation method and application
  • A kind of precursor and lithium manganese iron phosphate and its preparation method and application

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Embodiment approach

[0021] As mentioned above, M in the precursor is a doping element, which can improve the conductivity of the material. In the present invention, as a preferred embodiment of the present invention, the precursor may not contain doping elements. At this time, its general formula is Mn x Fe 1-x C 2 o 4 2H 2 O. Preferably, 0.5≤X≤0.8, more preferably 0.6≤X≤0.8.

[0022] In the present invention, the precursor is a single-phase solid-solution LMFP, and the inner manganese is evenly distributed, the iron content gradually decreases from the outside to the inside, and the manganese content gradually increases accordingly, and the Mn content of the surface layer is 0.

[0023] The present invention also provides a preparation method of the above-mentioned precursor, which method comprises water-soluble divalent manganese source, water-soluble ferrous iron source, water-soluble divalent metal M salt and precipitation agent except manganese salt and iron salt mixing and reacting, a...

Embodiment 1

[0053] This example is used to illustrate the precursor and lithium manganese iron phosphate provided by the present invention and its preparation method.

[0054] Dissolve 35.97 grams of ferrous nitrate and 200.81 grams of manganese nitrate in 5L of deionized water, dissolve 184.23 grams of potassium oxalate in 10L of deionized water, and then add ferrous nitrate and manganous nitrate to the potassium oxalate solution simultaneously and in parallel At the same time, dilute nitric acid was used to control the pH of the reaction solution to 6.5, and the reaction was stirred and reacted for 4 hours under circulating water at 50°C. After the reaction solution was left to age for 8 hours, the light yellow Mn was obtained after filtration, washing and drying. 0.8 Fe 0.2 C 2 o 4 2H 2 O material, denoted as QQT-A1.

[0055] in N 2 Dissolve 28.79 grams of ferrous nitrate in 2L of deionized water under protection, and after emulsification and dispersion, 179.12 grams of Mn 0.8 Fe...

Embodiment 2

[0073] This example is used to illustrate the lithium manganese iron phosphate provided by the present invention and its preparation method.

[0074] 139.12 grams of ferrous chloride tetrahydrate and 257.28 grams of manganous chloride tetrahydrate were respectively dissolved in 10L of deionized water, 267.98 grams of sodium oxalate were dissolved in 20L of deionized water, and then the ferrous chloride and manganous chloride At the same time, add it dropwise into the sodium oxalate solution in parallel, and control the pH of the reaction solution to 6 with dilute hydrochloric acid, stir and react for 2 hours under circulating water at 60°C, keep the reacted solution for 24 hours, filter, wash and dry Obtain light yellow Mn 0.65 Fe 0.35 C 2 o 4 2H 2 O material, denoted as QQT-A2.

[0075] in N 2 Dissolve 8.7 grams of ferrous acetate in 2L of deionized water under protection, and after emulsification and dispersion, 179.26 grams of Mn 0.65 Fe 0.35 C 2 o 4 2H 2 O powde...

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Abstract

The invention provides a precursor and LMFP and its preparation method and application. The preparation method of LMFP comprises the following steps: mixing the precursor, a water-soluble lithium source, a water-soluble phosphorus source and an organic carbon source, drying a mixture product and roasting. The water-soluble phosphorus source is phosphoric acid and / or water-soluble phosphate. By the above method, LMFP with less dissolution of ferromanganese and excellent cycle performance can be obtained.

Description

technical field [0001] The invention relates to a precursor, a preparation method of the precursor, a preparation method of lithium manganese iron phosphate, lithium manganese iron phosphate prepared by the method and an application of the lithium manganese iron phosphate as a positive electrode active material. Background technique [0002] The power lithium-ion battery has the advantages of high specific energy, high specific power, high safety and long cycle life, and is an ideal power source for future electric vehicles and various electric tools. Olivine-type lithium manganese phosphate (LMP for short) cathode material has the advantages of high working voltage, mild synthesis conditions, wide source of raw materials and no pollution to the environment. However, lithium manganese phosphate has a large amount of Mn at the end of charging 3+ , high spin Mn 3+ It will cause the Jahn-Teller effect, distort and break the structure of lithium manganese phosphate material, a...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01M4/58C01B25/45
CPCY02E60/10
Inventor 陈靖华徐茶清肖峰
Owner BYD CO LTD
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