A method for preparing battery-grade lithium iron phosphate using waste battery black powder as a lithium source

Abstract

The present invention belongs to the technical field of lithium iron phosphate preparation, and in particular, is a method for preparing battery-grade lithium iron phosphate using waste battery black powder as a lithium source. The method comprises the following steps: S1, mixing black powder, a conductive additive, and water, and stirring to obtain a black powder slurry; S2, mixing an intermediate carrier, a conductive additive, and water, and stirring to obtain a carrier slurry; S3, mixing iron phosphate with water, and stirring to obtain an iron phosphate slurry; S4, pumping the black powder slurry into a first CDI unit, and pumping the carrier slurry into the first CDI unit for lithium absorption; S5, pumping the carrier slurry into a second CDI unit, and pumping the iron phosphate slurry into the second CDI unit for lithium absorption; S6, sequentially subjecting the lithium iron phosphate that has completed lithium ion adsorption to solid-liquid separation, drying, and pulverizing, and then removing the remaining iron phosphate to obtain battery-grade lithium iron phosphate. The present invention utilizes waste battery black powder as a lithium source to prepare battery-grade lithium iron phosphate, with low energy consumption and no pollution.

Description

Technical Field

[0001] The present invention belongs to the field of lithium iron phosphate preparation, and in particular relates to a method for preparing battery-grade lithium iron phosphate by utilizing waste battery black powder as a lithium source. Background Art

[0002] Lithium iron phosphate is a lithium-ion battery electrode material characterized by large discharge capacity, low price, non-toxicity, and no environmental pollution. When used as a lithium battery, it has the advantages of being non-toxic, pollution-free, safe, widely available in raw materials, inexpensive, and long-lasting. It is an ideal positive electrode material for the new generation of lithium-ion batteries.

[0003] Existing recycling methods for used battery black powder primarily involve wet and pyrometallurgical methods to recover the lithium. After the lithium is recovered, it is then regenerated into battery-grade lithium iron phosphate via solid-phase or liquid-phase methods. The solid-phase method requires a high temperature of approximately 700 degrees Celsius, while the liquid-phase method also involves a high-temperature roasting process of 600-800 degrees Celsius. Both methods require environmentally friendly raw materials and preparation methods, and the production process is complex and energy-intensive, resulting in significant adverse effects on user experience. Therefore, a method for preparing battery-grade lithium iron phosphate using used battery black powder as a lithium source is urgently needed to address these issues. Summary of the Invention

[0004] To overcome the above-mentioned shortcomings of the prior art, the present invention provides a method for preparing battery-grade lithium iron phosphate using waste battery black powder as a lithium source. The present invention uses waste battery black powder as a lithium source to prepare battery-grade lithium iron phosphate, which has low energy consumption and is pollution-free.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A method for preparing battery-grade lithium iron phosphate using waste battery black powder as a lithium source, a method for preparing battery-grade lithium iron phosphate using waste battery black powder as a lithium source, characterized by comprising the following steps:

[0007] S1. Mix waste battery black powder, conductive additive and deionized water in a ratio of 50:(0.5-2):(200-1500) by mass, and stir for more than 10 hours to obtain a uniform black powder slurry;

[0008] S2. Mix the intermediate carrier, the conductive additive, and deionized water in a ratio of 50:(0.5-2):(200-1500) by mass, and stir for more than 10 hours to obtain a uniform carrier slurry;

[0009] S3, mixing ferric phosphate and deionized water in a mass ratio of 1: (4-50), stirring for more than 10 hours to obtain a uniform ferric phosphate slurry;

[0010] S4. The black powder slurry in the above step S1 is pumped into the positive electrode side slurry chamber of the No. 1 CDI device (capacitive deionization device) through a pump, and the carrier slurry in step S2 is pumped into the negative electrode side slurry chamber of the No. 1 CDI device (capacitive deionization device) through a pump, and lithium absorption is performed in a constant voltage mode to allow lithium ions to enter the intermediate carrier; in the No. 1 CDI device, the current collector at the black powder slurry end is connected to a positive charge, and the current collector at the carrier slurry end is connected to a negative charge, and a cation exchange membrane is provided between the positive electrode side slurry chamber and the negative electrode side slurry chamber;

[0011] S5. The carrier slurry in which lithium is inserted in the above step S4 is pumped into the positive electrode side slurry chamber of the No. 2 CDI device (capacitive deionization device) through a pump, and the iron phosphate slurry in step S3 is pumped into the negative electrode side slurry chamber of the No. 2 CDI device (capacitive deionization device) through a pump, and lithium absorption is performed in a constant voltage mode under power supply, so that lithium ions enter the negative electrode side slurry chamber of the No. 2 CDI device and are adsorbed by the iron phosphate to become lithium iron phosphate; the current collector of the lithium adsorption slurry end (iron phosphate slurry) of the No. 2 CDI device is negatively charged, and the current collector of the carrier slurry end is positively charged, and a cation exchange membrane is provided between the positive electrode side slurry chamber and the negative electrode side slurry chamber;

[0012] S6. Separate the lithium iron phosphate that has completed the lithium ion adsorption in the above step S5 into solid-liquid form, dry it, and crush it. After the crushing is completed, remove the remaining iron phosphate to obtain battery-grade lithium iron phosphate.

[0013] Preferably, the method comprises the following steps:

[0014] S1. Mix waste battery black powder, conductive additive and deionized water in a ratio of 50:(0.5-2):(200-1500) by mass, and stir for more than 10 hours to obtain a uniform black powder slurry;

[0015] S2. Mix the intermediate carrier, the conductive additive, and deionized water in a ratio of 50:(0.5-2):(200-1500) by mass, and stir for more than 10 hours to obtain a uniform carrier slurry;

[0016] S3, mixing ferric phosphate and deionized water in a mass ratio of 1: (4-50), stirring for more than 10 hours to obtain a uniform ferric phosphate slurry;

[0017] S4, pumping the black powder slurry in the above step S1 into the positive electrode side slurry chamber of the first CDI device (capacitive deionization device) through a pump, and pumping the carrier slurry in step S2 into the negative electrode side slurry chamber of the first CDI device (capacitive deionization device) through a pump, and connecting the power to perform lithium absorption in a constant voltage mode to allow lithium ions to enter the intermediate carrier;

[0018] S5. The carrier slurry in which lithium is inserted in step S4 is pumped into the positive electrode side slurry chamber of the second CDI device (capacitive deionization device) by a pump, and the iron phosphate slurry in step S3 is pumped into the negative electrode side slurry chamber of the second CDI device (capacitive deionization device) by a pump, and lithium absorption is performed in a constant voltage mode under power supply, so that lithium ions enter the negative electrode side slurry chamber of the second CDI device and are adsorbed by the iron phosphate to become lithium iron phosphate;

[0019] S6. Removing the remaining iron phosphate from the lithium iron phosphate that has completed the lithium ion adsorption in the above step S5, and then sequentially performing solid-liquid separation, drying and crushing to obtain battery-grade lithium iron phosphate.

[0020] Preferably, the conductive additive is one of acetylene black and Ketjen black, but is not limited to these two.

[0021] Preferably, the intermediate carrier is activated carbon or graphite, which plays the role of transporting lithium ions, but is not limited to these two.

[0022] Preferably, the constant voltage mode voltage in step S4 and step S5 is 2-5V, and the lithium on the battery black powder is stripped off under a specific voltage range without destroying the original molecular structure of the iron phosphate.

[0023] Preferably, the method for removing the iron phosphate in step S8 is a physical separation method or a chemical dissolution method, but is not limited to these two methods.

[0024] Preferably, the purity of the ferric phosphate in step S3 is ≥98.8%.

[0025] The advantages of the present invention are:

[0026] (1) The present invention first removes lithium ions from waste battery black powder materials through capacitor deionization technology and transfers them to activated carbon or graphite, and then re-embeds lithium ions into battery-grade iron phosphate materials through capacitor deionization technology to prepare battery-grade lithium iron phosphate. Waste battery black powder is used as a lithium source, and the materials used are cheap. The invention has the advantages of simple preparation method, cheap raw materials, less impact on the environment and low preparation energy consumption, and has broad application prospects.

[0027] (2) The method of preparing battery-grade lithium iron phosphate using waste battery black powder as a lithium source has less impact on the environment than other methods; and the energy consumption during operation is low. Compared with other methods, the preparation method saves more energy and reduces costs. It is not only suitable for industrial production, but also suitable for laboratory research. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a working principle diagram of the present invention. DETAILED DESCRIPTION

[0029] Example 1

[0030] like Figure 1 As shown, a method for preparing battery-grade lithium iron phosphate using waste battery black powder as a lithium source comprises the following steps:

[0031] S1. Mix waste battery black powder, acetylene black and deionized water in a ratio of 50:1:1000 by mass and stir at room temperature using a magnetic stirrer at a speed of 500 r / min for more than 12 hours to obtain a uniform black powder slurry;

[0032] S2. The activated carbon, acetylene black and deionized water were mixed in a mass ratio of 50:1:1000 and stirred at room temperature using a magnetic stirrer at a speed of 500 r / min for more than 12 hours to obtain a uniform activated carbon slurry;

[0033] S3. Battery-grade iron phosphate and deionized water were mixed in a mass ratio of 1:20 and stirred at room temperature using a magnetic stirrer at a speed of 500 r / min for more than 12 hours to obtain a uniform iron phosphate slurry;

[0034] S4. The black powder slurry from step S1 and the activated carbon slurry from step S2 were pumped into the positive and negative electrode slurry chambers of the first CDI device, respectively, using a peristaltic pump at a constant rate of 30 ml / min. A DC power supply was connected to the device under a constant voltage of 2.6 volts to perform lithium absorption, allowing the lithium ions in the black powder slurry to enter the activated carbon slurry.

[0035] S5. The activated carbon slurry and iron phosphate slurry, which were lithium-intercalated in step S4, were pumped into the positive and negative electrode slurry chambers of the second CDI unit, respectively, using a peristaltic pump at a constant rate of 30 ml / min. The unit was then powered and operated at a constant voltage of 2.6 volts to perform lithium absorption. This allowed lithium ions to enter the battery-grade iron phosphate slurry and be adsorbed by the iron phosphate to form lithium iron phosphate.

[0036] S6. The lithium iron phosphate adsorbed by the lithium ion in step S5 is subjected to solid-liquid separation;

[0037] S7. The lithium iron phosphate in step S6 is dried and crushed;

[0038] S8. The powder after the pulverization in the above step S7 is sieved to remove the iron phosphate to obtain battery-grade lithium iron phosphate.

[0039] Example 2

[0040] A method for preparing battery-grade lithium iron phosphate using waste battery black powder as a lithium source comprises the following steps:

[0041] S1. Mix waste battery black powder, acetylene black and deionized water in a ratio of 50:1:1000 by mass and stir at room temperature using a magnetic stirrer at a speed of 500 r / min for more than 12 hours to obtain a uniform black powder slurry;

[0042] S2. The activated carbon, acetylene black and deionized water were mixed in a mass ratio of 50:1:1000 and stirred at room temperature using a magnetic stirrer at a speed of 500 r / min for more than 12 hours to obtain a uniform activated carbon slurry;

[0043] S3. Battery-grade iron phosphate and deionized water were mixed in a mass ratio of 1:20 and stirred at room temperature using a magnetic stirrer at a speed of 500 r / min for more than 12 hours to obtain a uniform iron phosphate slurry;

[0044] S4. The black powder slurry from step S1 and the activated carbon slurry from step S2 were pumped into the positive and negative electrode slurry chambers of the first CDI device, respectively, using a peristaltic pump at a constant rate of 30 ml / min. A DC power supply was connected to the device under a constant voltage of 2.6 volts to perform lithium absorption, allowing the lithium ions in the black powder slurry to enter the activated carbon slurry.

[0045] S5. The activated carbon slurry and iron phosphate slurry, which were lithium-intercalated in step S4, were pumped into the positive and negative electrode slurry chambers of the second CDI unit, respectively, using a peristaltic pump at a constant rate of 30 ml / min. The unit was then powered and operated at a constant voltage of 2.6 volts to perform lithium absorption. This allowed lithium ions to enter the battery-grade iron phosphate slurry and be adsorbed by the iron phosphate to form lithium iron phosphate.

[0046] S6. The lithium iron phosphate solution prepared in step S5 is vacuum filtered using a microfiltration membrane to filter the iron phosphate that does not adsorb lithium ions. Depending on the filtration effect, deionized water can be added multiple times for vacuum filtration to remove the iron phosphate;

[0047] S7. The lithium iron phosphate after solid-liquid separation in step S6 is placed in an oven for drying;

[0048] S8. Crush the lithium iron phosphate dried in step S7 to obtain battery-grade lithium iron phosphate.

[0049] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing battery-grade lithium iron phosphate using waste battery black powder as a lithium source, characterized in that: The steps include: S1. Mix waste battery black powder, conductive additive and deionized water in a ratio of 50:(0.5-2):(200-1500) by mass, and stir for more than 10 hours to obtain a uniform black powder slurry; S2. Mix the intermediate carrier, the conductive additive, and deionized water in a ratio of 50:(0.5-2):(200-1500) by mass, and stir for more than 10 hours to obtain a uniform carrier slurry; S3, mixing ferric phosphate and deionized water in a mass ratio of 1: (4-50), stirring for more than 10 hours to obtain a uniform ferric phosphate slurry; S4, pumping the black powder slurry in step S1 into the positive electrode side slurry chamber of the first CDI device, pumping the carrier slurry in step S2 into the negative electrode side slurry chamber of the first CDI device, and connecting the power supply to perform lithium absorption in a constant voltage mode; S5. Pump the carrier slurry that has been intercalated with lithium in step S4 into the positive electrode slurry chamber of the second CDI device, and pump the iron phosphate slurry in step S3 into the negative electrode slurry chamber of the second CDI device, and connect the power supply to perform lithium absorption in a constant voltage mode. S6. Separate the lithium iron phosphate that has completed the lithium ion adsorption in the above step S5 into solid-liquid form, dry it, and crush it. After the crushing is completed, remove the remaining iron phosphate to obtain battery-grade lithium iron phosphate.

2. The method for preparing battery-grade lithium iron phosphate using waste battery black powder as a lithium source according to claim 1, characterized in that: The steps include: S1. Mix waste battery black powder, conductive additive and deionized water in a ratio of 50:(0.5-2):(200-1500) by mass, and stir for more than 10 hours to obtain a uniform black powder slurry; S2. Mix the intermediate carrier, the conductive additive, and deionized water in a ratio of 50:(0.5-2):(200-1500) by mass, and stir for more than 10 hours to obtain a uniform carrier slurry; S3, mixing ferric phosphate and deionized water in a mass ratio of 1: (4-50), stirring for more than 10 hours to obtain a uniform ferric phosphate slurry; S4, pumping the black powder slurry in step S1 into the positive electrode side slurry chamber of the first CDI device, pumping the carrier slurry in step S2 into the negative electrode side slurry chamber of the first CDI device, and connecting the power supply to perform lithium absorption in a constant voltage mode; S5. Pump the carrier slurry that has been intercalated with lithium in step S4 into the positive electrode slurry chamber of the second CDI device, and pump the iron phosphate slurry in step S3 into the negative electrode slurry chamber of the second CDI device, and connect the power supply to perform lithium absorption in a constant voltage mode. S6. Removing the remaining iron phosphate from the lithium iron phosphate that has completed the lithium ion adsorption in the above step S5, and then sequentially performing solid-liquid separation, drying and crushing to obtain battery-grade lithium iron phosphate.

3. A method for preparing battery-grade lithium iron phosphate using waste battery black powder as a lithium source according to claim 1 or 2, characterized in that: The conductive additive is one of acetylene black and Ketjen black.

4. A method for preparing battery-grade lithium iron phosphate using waste battery black powder as a lithium source according to claim 1 or 2, characterized in that: The intermediate carrier is activated carbon or graphite.

5. The method for preparing battery-grade lithium iron phosphate using waste battery black powder as a lithium source according to claim 1 or 2, characterized in that: The constant voltage mode voltage in step S4 and step S5 is 2-5V.

6. The method for preparing battery-grade lithium iron phosphate using waste battery black powder as a lithium source according to claim 1, characterized in that: The method for removing the iron phosphate in step S6 is a physical separation method or a chemical dissolution method.

7. The method for preparing battery-grade lithium iron phosphate using waste battery black powder as a lithium source according to claim 1 or 2, characterized in that: The purity of the ferric phosphate in step S3 is ≥98.8%.

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