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Method for reducing influences of impurity elements in ferrophosphorus on LixFeyPzO4

A technology of impurity elements and phosphorus elements, applied in the direction of non-metallic elements, chemical instruments and methods, phosphorus compounds, etc., can solve the problems of high cost of impurity removal, affecting the electrochemical performance of materials, etc., to improve the tap density, solve the problem of oxygen It is difficult to precisely control the quantity and easy to produce on an industrial scale

Inactive Publication Date: 2011-06-01
SICHUAN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

These impurity elements will affect the electrochemical performance of the material. At present, purification is carried out by melting and recrystallization methods, which need to be completed under an inert atmosphere at a higher temperature, and the cost of impurity removal is relatively high.

Method used

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  • Method for reducing influences of impurity elements in ferrophosphorus on LixFeyPzO4
  • Method for reducing influences of impurity elements in ferrophosphorus on LixFeyPzO4

Examples

Experimental program
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Effect test

Embodiment 1

[0027] Fe 2 Preparation of LiFePO from P and lithium carbonate 4 After dissolving ferrophosphorus with aqua regia, elemental analysis is carried out. The raw material of ferrophosphorus contains 67.7% Fe, 18.9% P, 6.3% Si, 2.1% Mn, 1.3% Ti, 1.2% V, 1.2% C, the remaining insoluble impurity content is 1.3%, according to the calculation, the composition of ferrophosphorus is approximately Fe 2 P, since C is burned off during the reaction, the real impurity elements are Si, Mn, Ti, V and insoluble impurities. It is worth noting that: according to literature reports, Si, Mn, Ti and V are beneficial to improve the 4 The electrochemical performance of the positive electrode material, and the impurity elements Si, Mn, Ti and V in the actual reaction process will affect the LiFePO 4 Perform in-situ self-doping. Here, it may be assumed that Si, Mn, Ti, V and insoluble impurities are the impurity elements to be removed in ferrophosphorus. According to their physical and chemical prope...

Embodiment 2

[0043] Preparation of LiFePO from iron phosphorus FeP and lithium hydroxide as raw materials 4 , after elemental analysis, the ferrophosphorus raw material contains 54.1% Fe, 29.8% P, 7.3% Si, 2.1% Mn, 1.5% Ti, 1.5% V, 2.2% C, and the remaining insoluble impurities are 1.5%, according to the calculation, the composition of ferrophosphorus is approximately FeP, since C is burned off during the reaction process, and 0.3% of other impurities are allowed to exist in battery grade raw materials, so the real impurity elements are Si, Mn, Ti, V and insoluble impurities, it is worth noting that according to literature reports Si, Mn, Ti and V are beneficial to improve LiFePO 4 The electrochemical performance of the positive electrode material, and the impurity elements Si, Mn, Ti and V in the actual reaction process will affect the LiFePO 4 Perform in-situ self-doping. Here, it may be assumed that Si, Mn, Ti, V and insoluble impurities are the impurity elements to be removed in ferr...

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Abstract

The invention relates to a simple method for reducing the influences of impurity elements in ferrophosphorus on LixFeyPzO4 (particularly LiFePO4, LiFe2 / 3PO4 and Li4 / 7Fe4 / 7P8 / 7O4), which comprises: reacting ferrophosphorus with a lithium salt react in an oxidizing atmosphere to obtain a product, leaching the product with acid and filtering the leachate; reacting the filtrate with phosphoric acid or a phosphate, and filtering the reaction solution to obtain high-purity Li3PO4 and FePO4 filtrate; concentrating the high-purity Li3PO4 and FePO4 filtrate, and graduating the concentrate to obtain Li3PO4 and FePO4 intermediates in special shapes; and adding supplementary phosphorus source, iron source or lithium source, mixing the supplementary phosphorus source, iron source or lithium source with the intermediates to perform a reaction in a non-oxidizing atmosphere to obtain the LixFeyPzO4. In the method, clean production is realized by the reaction design, raw material combination and by product utilization. In the method, a reaction process is used to remove the impurity elements in the ferrophosphorus and graduate the Li3PO4 and FePO4, the grain diameter and shape are easy to control,the oxygen amount is easy to control, the ferrophosphorus can replace reducing carbon as a reducer, the influences of the impurity elements in the ferrophosphorus on the LixFeyPzO4, the tap density of the LixFeyPzO4 product is improved, the production process is simple, the process steps are reduced, the reaction is easy to control, the steps are combined organically, no waste liquid is discharged, requirements on equipment are low, the cost is low, the investment is small, and the benefits are good. The method is suitable to be used for producing high-performance LixFeyPO4 from the ferrophosphorus at low cost.

Description

technical field [0001] The invention relates to a method for reducing impurity elements in ferrophosphorus to Li x Fe y P z o 4 The impact method can be applied to the recycling of resources and the low-cost development of high-performance electrode materials. Background technique [0002] Ferrophosphorus is an intermetallic compound formed by the reaction of phosphorus and iron. It contains the main elements Fe and P. It has a wide range of sources and the market price is not high. The composition of ferrophosphorus varies according to different phosphate rock raw materials and process conditions, and there are many types, generally in the following states: FeP, Fe 2 P, Fe 3 P and FeP 2 etc., chemically stable at room temperature, stainless, non-magnetic, with a melting point of about 1149°C. my country is rich in ferrophosphorus resources. Not only is there a large amount of phosphate iron ore smelting and preparation, but also there are many by-products in the prod...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C01B25/45
Inventor 王贵欣闫康平刘睿李秀丽陈妙
Owner SICHUAN UNIV
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