CN-121972493-A - Recovery method of waste lithium iron phosphate anode material

CN121972493ACN 121972493 ACN121972493 ACN 121972493ACN-121972493-A

Abstract

The invention provides a method for recycling waste lithium iron phosphate anode materials, and belongs to the technical field of lithium ion battery recycling. The method comprises the steps of carrying out solid-phase reaction on waste lithium iron phosphate anode materials at 700-770 ℃ by using calcium chloride to obtain ferrous chloride, calcium phosphate chloride and lithium chloride, volatilizing and collecting ferrous chloride in a gaseous form at the reaction temperature to carry out efficient separation of iron, cooling to obtain calcium phosphate chloride and lithium salt simultaneously, fully reacting lithium iron phosphate by limiting the dosage of the calcium chloride to improve the recovery rate of valuable elements, dissolving solid products obtained by the solid-phase reaction in water by utilizing the characteristic that the calcium phosphate chloride is insoluble in water, carrying out solid-liquid separation to obtain phosphorus salt and lithium salt solution to realize separation and recovery of phosphorus, and finally precipitating lithium in the lithium salt solution to realize recovery of lithium.

Inventors

LI HUI
LIU CHANG
ZHANG FUCHENG
LIANG JINGLONG
SONG JIAN
SONG LINGYUE
Ban Zekang
ZHANG XIN

Assignees

华北理工大学

Dates

Publication Date: 20260505
Application Date: 20260205

Claims (10)

1. A method for recycling waste lithium iron phosphate anode materials comprises the following steps: Mixing a waste lithium iron phosphate anode material with calcium chloride, sequentially heating and preserving heat, collecting tail gas in the preserving heat process, cooling the obtained non-gaseous product, and collecting a solid product, wherein the preserving heat temperature is 700-770 ℃, the heating, the preserving heat and the cooling are carried out in an inert atmosphere, and the mass ratio of the lithium iron phosphate to the calcium chloride in the waste lithium iron phosphate anode material is1 (1.3-1.5); mixing the solid product with water, and then carrying out solid-liquid separation to obtain a phosphorus-containing solid and a lithium-containing solution; And mixing the lithium-containing solution with a precipitant to perform a precipitation reaction to obtain lithium salt precipitate.
2. The recycling method according to claim 1, wherein the time for heat preservation is 5-15 hours.
3. The recycling method according to claim 1, wherein the heating rate is 5-10 ℃ per minute.
4. The recycling method of the lithium iron phosphate anode material is characterized in that the mass ratio of lithium iron phosphate to calcium chloride in the waste lithium iron phosphate anode material is 1 (1.4-1.45).
5. The recycling method according to claim 1, wherein the waste lithium iron phosphate anode material is obtained by recycling waste lithium iron phosphate electrodes, and the recycling comprises roasting the waste lithium iron phosphate electrodes to obtain the waste lithium iron phosphate anode material.
6. The recovery method according to claim 5, wherein the baking temperature is 400-500 ℃, the holding time is 1-3 hours, and the baking atmosphere is an inert atmosphere.
7. The recovery method according to claim 1, wherein the calcium chloride is pre-dried before use, the pre-drying temperature is 200-300 ℃, and the heat preservation time is 12-24 hours.
8. The recovery method according to claim 1, wherein the precipitant is a water-soluble carbonate or a water-soluble phosphate.
9. The recycling method according to claim 8, wherein the mass ratio of the precipitant to the waste lithium iron phosphate positive electrode material is (0.5-1): 1.
10. The recovery method according to claim 1, wherein the time of the precipitation reaction is 1 to 1.5 hours.

Description

Recovery method of waste lithium iron phosphate anode material Technical Field The invention belongs to the technical field of lithium ion battery recovery, and particularly relates to a recovery method of waste lithium iron phosphate anode materials. Background Lithium iron phosphate has been rapidly developed since it has the advantages of extremely high stability, safety, high energy density, low cost, long life and the like, and has been widely used in the fields of new energy automobiles, signal base stations, energy storage and the like since it was used as a positive electrode material of lithium ion batteries. With the widespread use of lithium iron phosphate, various problems have also been brought about, of which the most interesting is the recovery of waste lithium iron phosphate. The retirement of the lithium iron phosphate battery generates a large amount of accumulated waste lithium iron phosphate, occupies space and pollutes environment, and also causes the waste of resources, in particular to lithium which is called white petroleum in the new energy field. In the background of the problems of relatively shortage of lithium resources, high exploitation difficulty of natural lithium ores and the like in China, the method is particularly important for recycling the waste lithium iron phosphate. The most common method for recovering waste lithium iron phosphate is a wet recovery process at present, wherein the waste lithium iron phosphate is melted by alkali and then dissolved to obtain a phosphorus salt precipitate, phosphorus is separated, iron is recovered by electrodeposition, and finally lithium is precipitated again. The wet process has the problems of long process flow, complex process, high electrodeposition cost and the like, and has poor economic benefit. Disclosure of Invention The invention aims to provide a method for recycling waste lithium iron phosphate anode materials. The recovery method provided by the invention has the advantages of simple process, low cost, high added value of products and good economic benefit. In order to achieve the above object, the present invention provides the following technical solutions: The invention provides a method for recycling waste lithium iron phosphate anode materials, which comprises the following steps: Mixing a waste lithium iron phosphate anode material with calcium chloride, sequentially heating and preserving heat, collecting tail gas in the preserving heat process, cooling the obtained non-gaseous product, and collecting a solid product, wherein the preserving heat temperature is 700-770 ℃, the heating, the preserving heat and the cooling are carried out in an inert atmosphere, and the mass ratio of the lithium iron phosphate to the calcium chloride in the waste lithium iron phosphate anode material is1 (1.3-1.5); mixing the solid product with water, and then carrying out solid-liquid separation to obtain a phosphorus-containing solid and a lithium-containing solution; And mixing the lithium-containing solution with a precipitant to perform a precipitation reaction to obtain lithium salt precipitate. Preferably, the heat preservation time is 5-15 h. Preferably, the heating rate is 5-10 ℃ per minute. Preferably, the mass ratio of lithium iron phosphate to calcium chloride in the waste lithium iron phosphate anode material is 1 (1.4-1.45). Preferably, the waste lithium iron phosphate anode material is obtained by recycling a waste lithium iron phosphate electrode, and the recycling comprises roasting the waste lithium iron phosphate electrode to obtain the waste lithium iron phosphate anode material. Preferably, the roasting temperature is 400-500 ℃, the heat preservation time is 1-3 h, and the roasting atmosphere is an inert atmosphere. Preferably, the calcium chloride is pre-dried before use, the temperature of the pre-drying is 200-300 ℃, and the heat preservation time is 12-24 hours. Preferably, the precipitant is a water-soluble carbonate or a water-soluble phosphate. Preferably, the mass ratio of the precipitant to the waste lithium iron phosphate anode material is (0.5-1): 1. Preferably, the time of the precipitation reaction is 1-1.5 h. The invention provides a method for recycling waste lithium iron phosphate positive electrode materials, which comprises the steps of mixing waste lithium iron phosphate positive electrode materials with calcium chloride, sequentially heating and preserving heat, collecting tail gas in the preserving heat process, cooling obtained non-gaseous products, collecting solid products, preserving heat at 700-770 ℃, heating, preserving heat and cooling in inert atmosphere, mixing the solid products with water, performing solid-liquid separation to obtain phosphorus-containing solid and lithium-containing solution, and mixing the lithium-containing solution with a precipitator to perform precipitation reaction to obtain lithium salt precipitate. The method comprises the steps of carrying out solid-phase