Selective Lithium Extraction Process for Lithium Manganese Iron Phosphate Batteries

Abstract

The present invention discloses a process for selectively extracting lithium from lithium manganese iron phosphate batteries, belonging to the field of resource recovery and treatment of waste cathode materials for new energy batteries; the obtained waste LiMn 1‑x Fe x PO4 battery cathode powder is sulfuric acid acidified with H2SO4. After the reaction is completed, the acidified material is crushed and then subjected to oxidative roasting. After roasting, the material is washed with water to obtain a lithium-rich solution. The lithium-rich solution uses a LiOH solution as a precipitant to adjust the pH of the lithium-rich solution and remove metal impurities in the solution. Subsequently, sulfur is supplemented to the purified solution after impurity removal, and finally, the sulfur-supplemented solution is evaporated and crystallized to obtain Li2SO4; the present invention can effectively extract the lithium element in the LMFP cathode powder, and the lithium recovery rate is high. The whole process is simple, and the consumption of inorganic acids, organic acids, etc. is small or even zero, which can further reduce the enterprise's recycling cost and environmental pollution pressure.

Description

Technical Field

[0001] The invention relates to a selective lithium extraction process for lithium manganese iron phosphate batteries, and belongs to the field of resource recovery and treatment of waste positive electrode materials of new energy batteries. Background Art

[0002] Nowadays, the new energy vehicle industry is booming driven by environmental protection, and the annual shipments and retirements of lithium-ion batteries have increased significantly. Although the theoretical specific capacity of lithium iron phosphate cathode material (LiFePO4, LFP for short) batteries is lower than that of ternary batteries, LFP batteries have outstanding advantages such as high safety, long cycle life, good structural stability and cycle performance, environmental friendliness, and low cost. Therefore, lithium iron phosphate batteries are growing rapidly, and their market share has gradually surpassed ternary batteries. However, due to the two major disadvantages of this material: low electronic conductivity and small lithium ion diffusion coefficient, many cathode material manufacturers have conducted research on doping LFP materials to overcome the shortcomings of traditional LFP batteries. Mn is one of the commonly used elements, and its redox potential (Mn 2+ / Mn 3+ ) 2+ / Fe 3+ The price of raw materials is low, which is conducive to reducing the production cost of enterprises and improving commercial value.

[0003] Lithium iron manganese phosphate is a product of lithium iron phosphate and lithium manganese phosphate. It has the same structure as lithium iron phosphate, and both are orderly and regular olivine structures. Lithium iron manganese phosphate and lithium iron phosphate have the same advantages of low cost, high safety performance, high thermal stability, no spontaneous combustion during needle puncture and overcharging, long life, and safety without explosion risk. It can be said that it has the advantages of both lithium iron phosphate and lithium manganese phosphate, and can also make up for the shortcoming of low energy density of lithium iron phosphate. Therefore, it is also known as the "upgraded version of lithium iron phosphate."

[0004] LiMn 1-x Fe x PO4 has both the high energy density of LiMnPO4 and the good cycle performance of LiFePO4. It is a very promising positive electrode material for lithium-ion batteries. It is not difficult to see that lithium manganese iron phosphate is likely to enter large-scale production and is expected to be widely used in electric vehicles. It is even expected to replace lithium iron phosphate batteries in the future. 1-x The research on recycling of FexPO4 can not only provide early guidance for the recycling of retired batteries, but also reduce the production costs of enterprises, forming a closed-loop application of manufacturing and recycling. 1-x Fe x It is essential to recycle and reuse PO4.

[0005] At present, although there are methods for selectively extracting lithium from waste lithium iron phosphate materials, such as: a Chinese invention patent application with the application number CN201910571967.8 and the invention name of a method for selectively extracting lithium from waste lithium iron phosphate materials; a Chinese invention patent application with the application number CN202210198788.6 and the invention name of a method for directionally extracting lithium from waste lithium iron phosphate batteries; a Chinese invention patent application with the application number CN202310271675.9 and the invention name of a method for selectively extracting lithium based on synergistic oxidation leaching of waste lithium iron phosphate cathode powder; a Chinese invention patent application with the application number CN202111658312.8 and the invention name of a method for selectively extracting lithium from waste lithium ion batteries; a Chinese invention patent application with the application number CN201811147701.2 and the invention name of a method for selectively extracting lithium from lithium iron phosphate waste, etc. However, there is no method or process for selectively extracting and recycling lithium from LiMn 1-x Fe x PO4 batteries; and currently, the lithium extraction rate in the recycling process of waste lithium ion batteries is relatively low, while in the wet recycling process of LiMn 1-x Fe x PO4 cathode powder, the consumption of various inorganic acids and organic acids is relatively large. Summary of the Invention

[0006] (I) Invention Objective or Technical Problem to be Solved

[0007] 1. Selectively extract and recycle lithium from LiMn 1-x Fe x PO4 batteries.

[0008] 2. Improve the problem of relatively low lithium extraction rate in the current recycling process of waste lithium ion batteries.

[0009] 3. Optimize the problem of relatively large consumption of various inorganic acids and organic acids in the wet recycling process of LiMn 1-x Fe x PO4 cathode powder.

[0010] (II) Technical Solution

[0011] To achieve the above objective or solve the above technical problem, the present invention provides a process for selectively extracting lithium from lithium manganese iron phosphate batteries, which includes the following steps:

[0012] Step S1, after the waste LiMn 1-x Fe x PO4 battery is discharged, its cathode powder is obtained after disassembly, crushing and sorting;

[0013] Step S2: Sulfuric acid acidification is carried out on the positive electrode powder in Step S1, where n(Li + :H + ) = 1:0.5 - 1, that is, sulfuric acid and the positive electrode powder are mixed according to the molar ratio of n(Li + :H + ) = 1:0.5 - 1. After the reaction is completed, the acidified material is crushed (pulverized);

[0014] Step S3: The acidified material is subjected to oxidative roasting after being crushed, with the temperature being 450 - 700 °C and the roasting time being 3 - 8 h;

[0015] Step S4: The material is washed with water after roasting (the roasted slag is subjected to normal temperature water leaching treatment), with the liquid-solid ratio being 5 - 8:1, and washed at normal temperature for 2 h to obtain a Li-rich solution; After the above steps, the recovery rate of the valuable element Li in the positive electrode powder of the waste LiMn 1-x Fe x PO4 battery is 95%;

[0016] Step S5: Using LiOH solution as a precipitating agent for the Li-rich solution, adjusting the pH of the Li-rich solution to 8 - 11 to remove metal impurities in the solution to obtain a purified solution, and then using H2SO4 solution as a sulfur supplement agent to supplement sulfur to the purified solution until n(Li:S) = 2:1;

[0017] Step S6: Evaporative crystallization of the sulfur-supplemented solution at 80 - 120 °C can obtain Li2SO4.

[0018] Preferably, the H2SO4 in Step S2 is H2SO4 with a concentration of 16 - 18.5 mol / L.

[0019] Preferably, the liquid-solid ratio in the acidification process described in Step S2 is 2:1.

[0020] Preferably, the reaction temperature in Step S2 is 130 °C and the reaction time is 4 - 6 h.

[0021] Preferably, the temperature in the roasting process of Step S3 is 500 - 680 °C and the roasting reaction time is 4 - 5 h.

[0022] More preferably, the temperature in the roasting process of Step S3 is 650 °C and the roasting reaction time is 4 h.

[0023] Preferably, the LiOH solution in Step S5 is a 5 - 10% LiOH solution, and the pH of the Li-rich solution is adjusted to 8 - 9.

[0024] Preferably, in Step S6, evaporative crystallization of the sulfur-supplemented solution at 80 °C can obtain Li2SO4.

[0025] (III) Beneficial effects

[0026] The above technical solutions of the present invention have the following advantages:

[0027] 1. In the present invention, effective Li extraction can be achieved by subjecting the LMFP cathode powder to sulfuric acid acidification roasting. The process is simple, with low cost and low energy consumption, and can realize the selective extraction of lithium from the cathode material of waste LiMn 1-x Fe x PO4 batteries. The leaching rate of lithium is ≥97%, and the product has high value, with considerable economic benefits, which is conducive to promoting the recycling of LiMn 1-x Fe x PO4 batteries.

[0028] 2. The leaching process of the present invention is simple: in the water leaching process, there is no need to use other organic / inorganic acids or oxidants for leaching, which reduces the raw material and environmental protection costs, and can further reduce the enterprise's recycling cost and environmental pollution pressure; it avoids problems such as high recycling cost, high energy consumption, serious secondary pollution, and complex and lengthy treatment processes, and realizes the sustainable development of lithium-ion batteries.

[0029] In addition to the technical problems solved by the present invention, the technical features of the technical solutions constituted, and the advantages brought by these technical features of the technical solutions described above, the other technical features of the present invention and the advantages brought by these technical features will be further described in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the accompanying drawings required for the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other accompanying drawings can be obtained based on these drawings without creative efforts.

[0031] Figure 1 It is a schematic block diagram of the process flow of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0032] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

[0033] Such as Figure 1The figure shows a process flow block diagram for selectively extracting lithium from lithium manganese iron phosphate batteries.

[0034] Example 1

[0035] A process for selectively extracting lithium from lithium manganese iron phosphate batteries includes the following steps:

[0036] Step S1: After the used LiMn 1-x Fe x PO4 battery is discharged, its positive electrode powder is obtained after disassembly, crushing and sorting.

[0037] Step S2: The positive electrode powder in Step S1 is sulfuric acidified with 16 mol / L H2SO4, and the liquid-solid ratio of the two is 2:1, where n(Li + :H + ) = 1:1, that is, sulfuric acid and the positive electrode powder are mixed in a molar ratio of n(Li + :H + ) = 1:1. The reaction temperature is 130 °C, the reaction time is 4 h, and after the reaction is completed, the acidified material is crushed.

[0038] Step S3: After being crushed, the acidified material is subjected to oxidative roasting at a temperature of 450 °C for 8 h.

[0039] Step S4: After roasting, the material is washed with water, the liquid-solid ratio is 5:1, and it is washed at room temperature for 2 h to obtain a Li-rich solution.

[0040] Step S5: Using 5% LiOH solution as a precipitant, the pH of the Li-rich solution is adjusted to about 8 to remove metal impurities in the solution, and then H2SO4 solution is used as a sulfur supplement agent to supplement sulfur to the purified solution until n(Li:S) = 2:1.

[0041] Step S6: The sulfur-supplemented solution is evaporated and crystallized at 80 °C to obtain Li2SO4.

[0042] Example 2

[0043] A process for selectively extracting lithium from lithium manganese iron phosphate batteries includes the following steps:

[0044] Step S1: After the used LiMn 1-x Fe x PO4 battery is discharged, its positive electrode powder is obtained after disassembly, crushing and sorting.

[0045] Step S2: The positive electrode powder in Step S1 is sulfuric acidified with 18.5 mol / L H2SO4, and the liquid-solid ratio of the two is 2:1, where n(Li + :H + ) = 1:0.5, that is, sulfuric acid and the positive electrode powder are mixed in a molar ratio of n(Li + :H+ ) are mixed at a ratio of 1:0.5, the reaction temperature is 130 °C, the reaction time is 6 h, and after the reaction is completed, the acidified material is pulverized;

[0046] Step S3, the acidified material is subjected to oxidative roasting after pulverization, the temperature is 700 °C, and the roasting time is 3 h;

[0047] Step S4, the material is washed with water after roasting, the liquid-solid ratio is 8:1, and it is washed at room temperature for 2 h to obtain a Li-rich solution;

[0048] Step S5, the Li-rich solution uses 10% LiOH solution as a precipitant to adjust the pH of the Li-rich solution to about 8 to remove metal impurities in the solution, and then H2SO4 solution is used as a sulfur supplement agent to supplement sulfur to the purified solution until n(Li:S) = 2:1;

[0049] Step S6, the sulfur-supplemented solution is evaporated and crystallized at 120 °C to obtain Li2SO4.

[0050] Example 3

[0051] A process for selectively extracting lithium from lithium manganese iron phosphate batteries includes the following steps:

[0052] Step S1, the spent LiMn 1-x Fe x PO4 battery is disassembled, crushed and sorted after discharging to obtain its positive electrode powder;

[0053] Step S2, the positive electrode powder in Step S1 is sulfuric acid acidified with 18 mol / L H2SO4, the liquid-solid ratio of the two is 2:1, where n(Li + :H + ) = 1:0.8, that is, sulfuric acid and the positive electrode powder are mixed at a molar ratio of n(Li + :H + ) = 1:0.8, the reaction temperature is 130 °C, the reaction time is 4 h, and after the reaction is completed, the acidified material is pulverized;

[0054] Step S3, the acidified material is subjected to oxidative roasting after pulverization, the temperature is 650 °C, and the roasting time is 4 h;

[0055] Step S4, the material is washed with water after roasting, the liquid-solid ratio is 6:1, and it is washed at room temperature for 2 h to obtain a Li-rich solution;

[0056] Step S5, the Li-rich solution uses 8% LiOH solution as a precipitant to adjust the pH of the Li-rich solution to about 8 to remove metal impurities in the solution, and then H2SO4 solution is used as a sulfur supplement agent to supplement sulfur to the purified solution until n(Li:S) = 2:1;

[0057] In step S6, evaporating and crystallizing the S-supplemented solution at 80 °C can obtain Li2SO4.

[0058] Example 4

[0059] A process for selectively extracting lithium from lithium iron manganese phosphate batteries includes the following steps:

[0060] Step S1, after the used LiMn 1-x Fe x PO4 battery is discharged, its positive electrode powder is obtained after disassembly, crushing and sorting.

[0061] Step S2, acidifying the positive electrode powder in step S1 with 18 mol / L H2SO4, with a liquid-solid ratio of 2:1 between the two, where n(Li + :H + ) = 1:1, that is, sulfuric acid and the positive electrode powder are mixed in a molar ratio of n(Li + :H + ) = 1:1, the reaction temperature is 130 °C, the reaction time is 5 h, and after the reaction is completed, the acidified material is crushed.

[0062] Step S3, the acidified material is oxidized and roasted after being crushed, the temperature is 500 °C, and the roasting time is 5H.

[0063] Step S4, the material is washed with water after roasting, the liquid-solid ratio is 5:1, and it is washed at room temperature for 2H to obtain a Li-rich solution.

[0064] Step S5, using 6% LiOH solution as a precipitant to adjust the pH of the Li-rich solution to 9 to remove metal impurities in the solution, and then using H2SO4 solution as an S-supplementing agent to supplement S to the purified solution until n(Li:S) = 2:1.

[0065] Step S6, evaporating and crystallizing the S-supplemented solution at 90 °C can obtain Li2SO4.

[0066] Example 5

[0067] A process for selectively extracting lithium from lithium iron manganese phosphate batteries includes the following steps:

[0068] Step S1, after the used LiMn 1-x Fe x PO4 battery is discharged, its positive electrode powder is obtained after disassembly, crushing and sorting.

[0069] Step S2, acidifying the positive electrode powder in step S1 with 18 mol / L H2SO4, with a liquid-solid ratio of 2:1 between the two, where n(Li + :H + ) = 1:1, that is, sulfuric acid and the positive electrode powder are mixed in a molar ratio of n(Li +:H + ) are mixed in a ratio of 1:1, the reaction temperature is 130 °C, the reaction time is 5 h, and after the reaction is completed, the acidified material is pulverized;

[0070] Step S3, the acidified material is subjected to oxidative roasting after pulverization, the temperature is 600 °C, and the roasting time is 6H;

[0071] Step S4, the material is washed with water after roasting, the liquid-solid ratio is 6:1, and it is washed at room temperature for 2H to obtain a Li-rich solution;

[0072] Step S5, the Li-rich solution uses 8% LiOH solution as a precipitant to adjust the pH of the Li-rich solution to 8 to remove metal impurities in the solution, and then H2SO4 solution is used as a S supplement agent to supplement S in the purified solution to n(Li:S) = 2:1;

[0073] Step S6, the S-supplemented solution is evaporated and crystallized at 100 °C to obtain Li2SO4.

[0074] The specific embodiments of the present invention have been described in detail above in conjunction with the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those of ordinary skill in the art, various changes can be made without departing from the gist of the present invention.

Claims

1. Selective lithium extraction process for lithium iron manganese phosphate battery, characterized in that: It includes the following steps: Step S1, obtain the cathode powder of waste LiMn 1-x Fe x PO4 battery; Step S2: Sulfuric acid acidification is carried out on the positive electrode powder in Step S1. Sulfuric acid and the positive electrode powder are mixed in a molar ratio of n(Li + :H + ) = 1:0.5~1. After the reaction is completed, the material is pulverized; Step S3: The acidified material is crushed and then subjected to oxidative roasting at a temperature of 450 - 700 °C for a roasting time of 3 - 8 h; Step S4: The roasted material is washed with water. The liquid - solid ratio is 5 - 8:1, and it is washed at room temperature for 2 h to obtain a Li - rich solution; Step S5: Using LiOH solution as a precipitant for the Li - rich solution, adjusting the pH of the Li - rich solution to 8 - 9 to remove metal impurities in the solution. Subsequently, using H2SO4 solution as a sulfur - supplementing agent to supplement sulfur to the purified solution until n(Li:S) = 2:1; Step S6: The sulfur - supplemented solution is subjected to evaporation crystallization at 80 - 120 °C to obtain Li2SO4.

2. The selective lithium extraction process for lithium iron manganese phosphate battery according to claim 1, characterized in that: The concentration of H2SO4 in Step S2 is 16 - 18.5 mol / L.

3. The selective lithium extraction process for lithium iron manganese phosphate battery according to claim 2, characterized in that: The liquid - solid ratio during the acidification process described in Step S2 is 2:

1.

4. The selective lithium extraction process for lithium iron manganese phosphate battery according to claim 3, characterized in that: The reaction temperature in Step S2 is 130 °C, and the reaction time is 4 - 6 h.

5. The selective lithium extraction process for lithium iron manganese phosphate battery according to claim 4, characterized in that: The temperature during the roasting process in Step S3 is 500 - 680 °C, and the roasting reaction time is 4 - 5 h.

6. The selective lithium extraction process for lithium iron manganese phosphate battery according to claim 5, characterized in that: The temperature during the roasting process in Step S3 is 650 °C, and the roasting reaction time is 4 h.

7. The selective lithium extraction process for lithium iron manganese phosphate battery according to claim 6, characterized in that: The LiOH solution used in Step S5 is a 5 - 10% LiOH solution.

8. The selective lithium extraction process for lithium iron manganese phosphate battery according to claim 7, characterized in that: In Step S6, the sulfur - supplemented solution is subjected to evaporation crystallization at 80 °C to obtain Li2SO4.

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