New method for preparing LixFeyPzO4 by using ferro phosphorus

Abstract

The invention relates to a new method for preparing LixFeyPzO4 (particularly LiFePO4, LiFe2 / 3PO4 and Li4 / 7Fe4 / 7P8 / 7O4) by using ferro phosphorus, which comprises the following steps of: supplying an oxygen source for oxidizing P in the ferro phosphorus by only utilizing the oxygen in raw materials, proportioning in the mol ratio of the total phosphorus element to the total oxygen element of 1.0:(1.5-9.0), mixing the raw materials and then carrying out one-step reaction in a closed system at the temperature of 500-900 DEG C to obtain a product. The oxidation-reduction reacted material balance of the raw materials per se is realized in the closed system, without external oxygen sources, thereby solving a series of technical difficult problems caused by difficult oxygen quantity accurate control and oxygen introduction and eliminating the pollution of a large amount of waste gas during roasting by adopting an inert atmosphere or a carbide split product reducing atmosphere; the reaction is finished in the closed system, and the complete reaction is promoted by utilizing the pressure of the reaction per se, thereby reducing the volatilization of substances, such as lithium and the likein the raw materials, at high temperature and causing the product to be looser; and the method has no pollutant discharge in the preparation process, cleanness, environmental protection, short reaction flow, simple process, easy reaction operation, low requirement for equipment, low cost, less investment and good benefit and is easy to realize industrialization and suitable for producing high-performance LixFeyPzO4 by using the ferro phosphorus with low cost.

Description

technical field

[0001] The present invention relates to a kind of preparation Li by ferrophosphorus x Fe y P z o 4 The new method uses only the oxygen in the raw material to provide an oxygen source for oxidation of P in ferrophosphorus, realizes the material balance of the redox reaction of the raw material itself in a closed system, reduces the volatilization of lithium and other substances in the raw material at high temperature, and is clean and environmentally friendly , the process is simple, and can be applied to the low-cost development of high-performance electronic materials. Background technique

[0002] Currently preparing LiFePO 4 For electrode materials, N 2 Or the Ar inert atmosphere and the reducing atmosphere of the carbide cracking product, a large amount of protective gas needs to be continuously passed for protection during the reaction process, resulting in relatively large equipment investment, relatively large raw material consumption, relatively ...

Examples

Embodiment 1

[0022] Ferrophosphorus FeP, Fe(CO) 5 , Li 3 PO 4 Preparation of LiFePO as raw material 4 , as Fe(CO) 5 As the precursor of the conductive agent, with P element as the balance agent, FeP, Fe(CO) 5 , P, Li 3 PO 4 Dosing according to the molar ratio of 7:8:3:5, mixed evenly, transferred to a closed tube furnace and roasted at 600-800°C for 15-25 hours to obtain carbon-doped LiFePO 4 , the reaction that occurs is as follows:

[0023] 7FeP+8Fe(CO) 5 +5Li 3 PO 4 +3P→15LiFePO 4 +40C

[0024] Fe(CO) 5 The raw material is obtained by the reaction of Fe and CO, and CO can be reduced to CO by C 2 , so that the greenhouse gas CO 2 Through this reaction, it is converted into C, reducing greenhouse gas emissions and realizing a low-carbon economy, and the C generated by the reaction is used as LiFePO 4 In-situ doping of conductive agent, no other by-products are generated, the whole process is clean and environmentally friendly, and the product has a better crystal form, such...

Embodiment 2

[0026] Fe 1.5 P, Fe 2 o 3 ,P 2 o 5 , Li 2 CO 3 Preparation of LiFePO as raw material 4 , the Fe 1.5 P, Fe 2 o 3 ,P 2 o 5 , Li 2 CO 3 Dosing according to the molar ratio of 4:16:17:19.05, with 5-10% glucose as the precursor of the conductive agent, mixed evenly, transferred to a closed reaction kettle with a pressure reducing valve and reacted at 600-800°C for 16- 25 hours, get LiFePO 4 , the reaction that occurs is as follows:

[0027] 4Fe 1.5 P+16Fe 2 o 3 +17P 2 o 5 +19Li 2 CO 3 →38LiFePO 4 +19CO 2 ↑

[0028] The separated CO 2 After the product is absorbed by LiOH solution, it can be concentrated and dried to make Li 2 CO 3 Raw materials can also be reacted with Fe after carbon reduction to produce Fe(CO) 5 , as the raw material of Example 1, no other by-products are generated, and green and clean process production is realized. Prepared LiFePO 4 The product is relatively loose and has a good olivine structure, such as figure 2 shown.

Embodiment 3

[0030] FeP 2 , Fe 2 o 3 ,P 2 o 5 , Li 2 o 2 Preparation of LiFePO as raw material 4 , with 5-10wt.% ferrophosphorus as the conductive agent, and Fe as the balancer, the FeP 2 , Fe, Fe 2 o 3 ,P 2 o 5 , Li 2 o 2 Dosing according to the molar ratio of 1:1:3:3:4, mixed evenly, milled with 500rpm high-energy ball for 1-5h, then transferred to a closed muffle furnace and roasted at 650-800°C for 5-10 hours to obtain LiFePO 4 , the reaction that occurs is as follows:

[0031] FeP 2 +Fe+3Fe 2 o 3 +3P 2 o 5 +4Li 2 o 2 →8LiFePO 4

[0032] No other by-products are produced in the reaction, and the whole production process is green, clean and environmentally friendly.

technical field

[0001] The present invention relates to a kind of preparation Li by ferrophosphorus x Fe y P z o 4 The new method uses only the oxygen in the raw material to provide an oxygen source for oxidation of P in ferrophosphorus, realizes the material balance of the redox reaction of the raw material itself in a closed system, reduces the volatilization of lithium and other substances in the raw material at high temperature, and is clean and environmentally friendly , the process is simple, and can be applied to the low-cost development of high-performance electronic materials. Background technique

[0002] Currently preparing LiFePO 4 For electrode materials, N 2 Or the Ar inert atmosphere and the reducing atmosphere of the carbide cracking product, a large amount of protective gas needs to be continuously passed for protection during the reaction process, resulting in relatively large equipment investment, relatively large raw material consumption, relatively ...

Examples

Embodiment 1

[0022] Ferrophosphorus FeP, Fe(CO) 5 , Li 3 PO 4 Preparation of LiFePO as raw material 4 , as Fe(CO) 5 As the precursor of the conductive agent, with P element as the balance agent, FeP, Fe(CO) 5 , P, Li 3 PO 4 Dosing according to the molar ratio of 7:8:3:5, mixed evenly, transferred to a closed tube furnace and roasted at 600-800°C for 15-25 hours to obtain carbon-doped LiFePO 4 , the reaction that occurs is as follows:

[0023] 7FeP+8Fe(CO) 5 +5Li 3 PO 4 +3P→15LiFePO 4 +40C

[0024] Fe(CO) 5 The raw material is obtained by the reaction of Fe and CO, and CO can be reduced to CO by C 2 , so that the greenhouse gas CO 2 Through this reaction, it is converted into C, reducing greenhouse gas emissions and realizing a low-carbon economy, and the C generated by the reaction is used as LiFePO 4 In-situ doping of conductive agent, no other by-products are generated, the whole process is clean and environmentally friendly, and the product has a better crystal form, such...

Embodiment 2

[0026] Fe 1.5 P, Fe 2 o 3 ,P 2 o 5 , Li 2 CO 3 Preparation of LiFePO as raw material 4 , the Fe 1.5 P, Fe 2 o 3 ,P 2 o 5 , Li 2 CO 3 Dosing according to the molar ratio of 4:16:17:19.05, with 5-10% glucose as the precursor of the conductive agent, mixed evenly, transferred to a closed reaction kettle with a pressure reducing valve and reacted at 600-800°C for 16- 25 hours, get LiFePO 4 , the reaction that occurs is as follows:

[0027] 4Fe 1.5 P+16Fe 2 o 3 +17P 2 o 5 +19Li 2 CO 3 →38LiFePO 4 +19CO 2 ↑

[0028] The separated CO 2 After the product is absorbed by LiOH solution, it can be concentrated and dried to make Li 2 CO 3 Raw materials can also be reacted with Fe after carbon reduction to produce Fe(CO) 5 , as the raw material of Example 1, no other by-products are generated, and green and clean process production is realized. Prepared LiFePO 4 The product is relatively loose and has a good olivine structure, such as figure 2 shown.

Embodiment 3

[0030] FeP 2 , Fe 2 o 3 ,P 2 o 5 , Li 2 o 2 Preparation of LiFePO as raw material 4 , with 5-10wt.% ferrophosphorus as the conductive agent, and Fe as the balancer, the FeP 2 , Fe, Fe 2 o 3 ,P 2 o 5 , Li 2 o 2 Dosing according to the molar ratio of 1:1:3:3:4, mixed evenly, milled with 500rpm high-energy ball for 1-5h, then transferred to a closed muffle furnace and roasted at 650-800°C for 5-10 hours to obtain LiFePO 4 , the reaction that occurs is as follows:

[0031] FeP 2 +Fe+3Fe 2 o 3 +3P 2 o 5 +4Li 2 o 2 →8LiFePO 4

[0032] No other by-products are produced in the reaction, and the whole production process is green, clean and environmentally friendly.

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