Method for efficiently recovering waste lithium iron phosphate through oxygen-sodium persulfate leaching

Abstract

The invention belongs to the field of recycling treatment of waste lithium iron phosphate batteries, and particularly relates to a method for efficiently recycling waste lithium iron phosphate through oxygen-sodium persulfate leaching. According to the method, the lithium in the lithium iron phosphate waste battery is leached and extracted by adopting the environment-friendly reaction solution, and oxygen is additionally introduced in the extraction process, so that the leaching rate of the lithium is effectively improved, the leaching rate of iron is effectively reduced, and the overall leaching time is effectively shortened; therefore, the problem of secondary pollution to the environment when inorganic acid / alkali is recycled by an existing wet method is avoided, the process is low in cost and easy to implement, the extraction rate is high, and economic benefits of waste LFP battery recycling are considered from multiple aspects.

Description

Technical Field

[0001] The invention belongs to the field of waste lithium iron phosphate battery recycling and treatment, and specifically provides a high-efficiency waste lithium iron phosphate recycling method by oxygen-sodium persulfate leaching. Background Art

[0002] Lithium-ion batteries (LIBs) are important energy storage devices for lightweight and mobile commercial applications. This is primarily due to their high energy density, ever-expanding energy capacity, high battery voltage, wide operating temperature range, and high stability during charge and discharge cycles. These characteristics have led to their widespread use in portable electronic devices such as computers, digital cameras, and smartphones. Lithium-ion batteries have now become an essential part of everyday life, entering millions of households.

[0003] Ternary lithium batteries have been developing rapidly for some time, quickly gaining ground in the new energy battery sector. However, lithium iron phosphate batteries have attracted the attention of numerous companies and domestic researchers, leading to a wider application and a growing number of products. In recent years, with the rapid global development of the electric vehicle industry, the number of lithium iron phosphate batteries has gradually increased. Approximately 13,000 tons of lithium iron phosphate materials are used in the production of lithium iron phosphate batteries worldwide, with approximately 75% of this material sold to China, and this amount is increasing annually.

[0004] Since lithium iron phosphate batteries have a theoretical lifespan of 6-8 years, they are entering a period of widespread retirement. If these used batteries are not handled properly, the heavy metals contained in them can enter the human body, damaging organs and the immune system. Furthermore, the decomposition of these batteries produces various toxic and hazardous substances, such as lead, cadmium, and mercury, which are also harmful to the soil, water sources, and the atmosphere. Furthermore, the toxic and hazardous substances contained in used batteries accumulate in the soil and water, seeping into groundwater and surface water, causing serious water pollution.

[0005] More than 150 companies in my country have taken the lead in conducting relevant research applications and exploring business models. The recycling method currently widely used in the market is mainly wet recycling, that is, based on the different precipitation conditions of various elements in the positive electrode materials of power batteries, various acid and alkali solutions are selected to extract the elements in the positive electrode materials in the form of simple substances or compounds. This method is mostly used to recycle ternary power batteries containing high-value metals such as nickel, cobalt and manganese, and has high economic benefits. For lithium iron phosphate power batteries, their value is mainly concentrated in the lithium element in the positive electrode material. The existing wet recycling method not only has low economic benefits, but the waste acid and alkali generated during the recycling process will cause secondary pollution to the environment. Summary of the Invention

[0006] In view of the above problems or shortcomings, in order to solve the problems of low efficiency and secondary pollution in the existing recycling of waste lithium iron phosphate batteries, the present invention provides an efficient waste lithium iron phosphate recycling method using oxygen-sodium persulfate leaching.

[0007] An efficient waste lithium iron phosphate recovery method using oxygen-sodium persulfate leaching comprises the following steps:

[0008] Step 1: At least one of sodium persulfate, sodium hypochlorite and sodium perchlorate is used as a solute and dissolved in water to prepare a reaction solution with a molar concentration of 0.1 to 1.0 mol / L.

[0009] Step 2: Place the waste lithium iron phosphate powder in the reaction solution prepared in step 1, introduce oxygen and stir the reaction at a temperature of 25-60° C. for 6-24 hours until the reaction is completed to obtain a suspension.

[0010] Step 3: Separate the suspension obtained in step 2 into residue and liquid, collect and dry the residue to obtain FePO4, and concentrate the filtrate to obtain a lithium-containing concentrated solution.

[0011] Furthermore, in step 1, single sodium persulfate is used as the solute.

[0012] Furthermore, the concentration of the reaction solution in step 1 is 0.1 Mol / L.

[0013] Furthermore, the reaction temperature in step 2 is room temperature, which is beneficial to the cost control of the process and equipment.

[0014] Furthermore, the slag-liquid separation method in step 3 is suction filtration.

[0015] In summary, the present invention uses an environmentally friendly reaction solution to leach and extract lithium from waste lithium iron phosphate batteries, and by additionally introducing oxygen during the extraction process, the lithium leaching rate is effectively increased and the iron leaching rate is reduced, and the overall leaching time is effectively shortened; ultimately, the present invention avoids the problem of secondary pollution to the environment caused by the use of inorganic acids / alkalis in existing wet recovery, has a low and easy process cost, a high lithium extraction rate, and takes into account the economic benefits of recycling waste LFP batteries from multiple aspects. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 Schematic diagram of the reaction mechanism of the embodiment. DETAILED DESCRIPTION

[0017] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Figure 1 Schematic diagram of the reaction mechanism of the embodiment.

[0018] Example 1

[0019] An efficient waste lithium iron phosphate recovery method using oxygen-sodium persulfate leaching comprises the following steps:

[0020] Step 1: Dissolve Na2S2O8 in an aqueous solution to prepare a reaction solution with a concentration of 0.1M.

[0021] Step 2: Add 3.15 g of waste lithium iron phosphate powder into 100 ml of reaction solution, introduce oxygen, and stir at room temperature for 6 hours.

[0022] Step 3: Filter the suspension after the reaction, rinse with clean water, collect and dry the filter residue to obtain FePO4; and concentrate the filtrate to obtain a lithium ion-containing concentrated solution.

[0023] Comparative Example 1

[0024] Step 1: Dissolve Na2S2O8 in an aqueous solution to prepare a reaction solution with a concentration of 0.1M.

[0025] Step 2: Add 3.15 g of waste lithium iron phosphate powder into 100 ml of reaction solution and stir at room temperature for 6 h.

[0026] Step 3: Filter the suspension after the reaction, rinse with clean water, collect and dry the filter residue to obtain FePO4; and concentrate the filtrate to obtain a lithium ion-containing concentrated solution.

[0027] The waste lithium iron phosphate powder, the FePO4 obtained in Example 1, and the FePO4 obtained in Comparative Example 1 were subjected to ICP-MS to test the lithium content in the samples to determine the delithiation effect.

[0028] Sample name Lithium content (w%) Leaching rate Waste lithium iron phosphate 3.57％ Example 1 0.133％ 96.3％ Comparative Example 1 1.46％ 59.1％

[0029] Example 2

[0030] An efficient waste lithium iron phosphate recovery method using oxygen-sodium persulfate leaching comprises the following steps:

[0031] Step 1: Dissolve Na2S2O8 in an aqueous solution to prepare a reaction solution with a concentration of 0.1M.

[0032] Step 2: 3.15 g of waste lithium iron phosphate powder was added to 100 ml of reaction solution, and oxygen was introduced and stirred at room temperature for 12 hours.

[0033] Step 3: The suspension after the reaction is filtered, rinsed with water, and the residue is collected and dried to obtain FePO4. The filtrate is concentrated to obtain a concentrated solution containing lithium ions.

[0034] Comparative Example 2

[0035] Step 1: Dissolve Na2S2O8 in an aqueous solution to prepare a reaction solution with a concentration of 0.1M.

[0036] Step 2: Add 3.15 g of waste lithium iron phosphate powder into 100 ml of the reaction solution and stir at room temperature for 12 h.

[0037] Step 3: The suspension after the reaction is filtered, rinsed with water, and the residue is collected and dried to obtain FePO4. The filtrate is concentrated to obtain a concentrated solution containing lithium ions.

[0038] The waste lithium iron phosphate powder, the FePO4 obtained in Example 2, and the FePO4 obtained in Comparative Example 2 were subjected to ICP-MS to test the lithium content in the samples to determine the delithiation effect.

[0039] Sample name Lithium content (w%) Leaching rate Waste lithium iron phosphate 3.57％ Example 2 0.069％ 98.1％ Comparative Example 2 0.719％ 79.8％

[0040] It can be seen from the examples and comparative examples that the participation of oxygen greatly improves the efficiency of leaching lithium from lithium iron phosphate, and the reaction time is fast, and the secondary pollution generated is small, which is conducive to the recovery and reuse of lithium from waste lithium iron phosphate.

Claims

1. An efficient waste lithium iron phosphate recovery method using oxygen-sodium persulfate leaching, characterized in that: The following steps are involved: Step 1, using at least one of sodium persulfate, sodium hypochlorite and sodium perchlorate as a solute, dissolving in water to prepare a reaction solution with a molar concentration of 0.1 to 1.0 Mol / L; Step 2, placing the waste lithium iron phosphate powder in the reaction solution prepared in step 1, introducing oxygen and stirring the reaction at a temperature of 25-60° C. for 6-24 hours until the reaction is completed, to obtain a suspension; Step 3: Separate the suspension obtained in step 2 into residue and liquid, collect and dry the residue to obtain FePO4, and concentrate the filtrate to obtain a lithium-containing concentrated solution.

2. The high-efficiency waste lithium iron phosphate recovery method of oxygen-sodium persulfate leaching as claimed in claim 1, characterized in that: In the step 1, single sodium persulfate is used as the solute.

3. The high-efficiency waste lithium iron phosphate recovery method of oxygen-sodium persulfate leaching as claimed in claim 1 is characterized in that: The concentration of the reaction solution in step 1 is 0.1 Mol / L.

4. The high-efficiency waste lithium iron phosphate recovery method of oxygen-sodium persulfate leaching as claimed in claim 1, characterized in that: The reaction temperature in step 2 is room temperature.

5. The high-efficiency waste lithium iron phosphate recovery method of oxygen-sodium persulfate leaching as claimed in claim 1, characterized in that: The method of separating the slag and liquid in step 3 is suction filtration.

Images