A method for preparing a single-crystal fluorine-doped ternary positive electrode material using battery black powder

Abstract

This invention relates to the field of waste lithium-ion battery material recycling technology, and particularly to a method for preparing single-crystal fluorine-doped ternary cathode material using battery black powder. The method includes: high-temperature calcination pretreatment of the black powder; sulfuric acid dissolution and leaching; removal of copper, aluminum, iron, calcium, and magnesium impurities; co-precipitation of nickel, cobalt, and manganese at pH 11.2-14, followed by conversion to oxalate using oxalic acid; lithium replenishment and in-situ fluorine doping during calcination using residual fluorine-containing substances in the black powder to obtain regenerated ternary cathode material; and finally, recovery of lithium carbonate from lithium-rich solution. This invention can efficiently recover Ni, Co, Mn, and Li, with an overall recovery rate exceeding 90%. It can also effectively remove impurities such as Cu, Al, Fe, Ca, and Mg, improving material purity. The single-crystal fluorine-doped regenerated ternary material exhibits good cycle stability and rate performance. This invention significantly improves the purity and electrochemical performance of the regenerated material through multi-stage deep impurity removal and in-situ fluorine doping technology. The process is simple, resource utilization is high, and it is suitable for industrial production.

Description

Technical Field

[0001] This invention relates to the field of waste lithium-ion battery material recycling technology, and in particular to a method for preparing single-crystal fluorine-doped ternary cathode material using battery black powder. Background Technology

[0002] With the large-scale application of power batteries and energy storage batteries, the recycling and reuse of waste lithium-ion batteries has become an important way to solve resource shortages and environmental pollution. The black powder in waste batteries contains important metal elements such as lithium (Li), nickel (Ni), cobalt (Co), and manganese (Mn), as well as impurities such as copper (Cu), aluminum (Al), iron (Fe), calcium (Ca), and magnesium (Mg).

[0003] In existing technologies, traditional hydrometallurgy and pyrometallurgy suffer from high energy consumption, severe pollution, low metal recovery rates, and difficulty in achieving high-performance regenerated cathode materials. Furthermore, doping fluorine atoms into the lattice of regenerated ternary materials can significantly improve the structural stability and cycle performance of the materials, but existing processes struggle to achieve economical and efficient in-situ fluorine doping. To address these issues, this application proposes an innovative process route that utilizes multi-stage countercurrent extraction, precise control of chemical precipitation, and the utilization of residual fluorine in the raw materials to achieve in-situ doping. The aim is to provide a simple, efficient, and high-performance method for recovering black powder and regenerating ternary cathode materials. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of existing technologies by proposing a method for preparing single-crystal fluorine-doped ternary cathode materials using battery black powder. This method can efficiently recover Li, Ni, Co, and Mn while removing impurities such as Cu, Al, Fe, Ca, and Mg, thereby achieving the preparation of high-purity, high-performance regenerated ternary cathode materials.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A method for preparing single-crystal fluorine-doped ternary cathode material using battery black powder includes the following steps:

[0007] Step 1: Calcine the waste battery black powder at high temperature to remove impurities such as carbon and PVDF binder;

[0008] Step 2: Dissolve the pretreated battery black powder using sulfuric acid solution;

[0009] Step 3: Remove impurities such as copper, iron, aluminum, calcium, and magnesium from the solution. The specific steps are as follows:

[0010] Copper was extracted using a 5% organic phase by mixing 984H extractant with 260# sulfonated kerosene. A two-stage countercurrent extraction process was employed. Then, an equistoichiometric, equimolar ratio of sodium chlorate solution was added, followed by the addition of 2.0 M sodium carbonate solution to adjust the pH to 4.0-4.5 for precipitation to remove iron and aluminum. The slurry after iron and aluminum removal was filtered, and the resulting filtrate was piped to a purification and calcium removal tank. Sodium carbonate was added to remove calcium and magnesium, and the solution was then filtered to obtain a high-purity transition metal solution.

[0011] Step 4: Precipitate nickel-cobalt-manganese using sodium hydroxide or potassium hydroxide to obtain nickel-cobalt-manganese hydroxide;

[0012] Step 5: Treat nickel cobalt manganese oxide with oxalic acid to obtain nickel cobalt manganese oxalate;

[0013] Step 6: Lithium replenishment and regeneration of nickel cobalt manganese oxalate, followed by high-temperature sintering to obtain a regenerated ternary cathode material with monocrystalline fluorine doping;

[0014] Step 7: The remaining waste liquid after filtering nickel cobalt manganese hydroxide in Step 4 is concentrated 20-50 times at 80-95℃, and then a saturated sodium carbonate solution is added at 95℃. The mixture is stirred continuously, and the white solid precipitated is lithium carbonate powder.

[0015] Preferably, in step 1, the calcination temperature is 500-650°C and the time is 3-5 h.

[0016] Preferably, in step 2, the sulfuric acid solution can be replaced with hydrochloric acid or nitric acid solution, the reaction temperature is 60-75 °C, the reaction time is 1-4 h, and the solid-liquid ratio of battery black powder to sulfuric acid solution is 20 g / L.

[0017] Preferably, in step 2, the concentration of the sulfuric acid solution is 1.0-5.0 M.

[0018] Preferably, in step 4, the pH of the reaction extract is controlled between 11.2 and 14, and corresponding metal sulfates are added to adjust the transition metal ratio to nickel:cobalt:manganese of 1:1:1, 5:2:3, 6:2:2, 8:1:1 or 9:0.5:0.5.

[0019] Preferably, in step 5, the concentration of oxalic acid solution is 0.5-2.5M, the reaction temperature is 40-80℃, the reaction time is 1-3h, and the solid-liquid ratio of nickel cobalt manganese hydroxide to oxalic acid solution is 10-30g / L.

[0020] Preferably, in step 6, the sintering parameters are 500 °C for 4 hours, followed by heating to 800-850 °C and holding for 12 hours, with a heating rate of 5 °C / min.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] 1. This invention can efficiently recover Ni, Co, Mn, and Li, with an overall recovery rate of over 90%. It can also effectively remove impurities such as Cu, Al, Fe, Ca, and Mg, improving material purity. The resulting single-crystal fluorine-doped regenerated ternary material exhibits good cycle stability and rate performance.

[0023] 2. This invention significantly improves the purity and electrochemical performance of recycled materials through multi-stage deep impurity removal and in-situ fluorine doping technology. The process is simple, resource utilization is high, and it is suitable for industrial production. Attached Figure Description

[0024] Figure 1 The image shows a SEM image of regenerated NCM811 prepared in Example 1 of this invention.

[0025] Figure 2 The diagram shows the 1C charge-discharge cycle performance of the regenerated NCM811 prepared in Example 1 of the present invention after being assembled into a coin cell.

[0026] Figure 3 This is an SEM image of the black powder after calcination pretreatment in Example 2 of the present invention;

[0027] Figure 4 The XRD pattern of the transition metal oxalate precursor prepared in Example 2 of this invention;

[0028] Figure 5 The XRD pattern of regenerated NCM811 prepared in Example 2 of this invention;

[0029] Figure 6 XPS spectrum of regenerated NCM811 prepared in Example 2 of this invention;

[0030] Figure 7 The diagram shows the rate performance of the regenerated NCM811 prepared in Example 2 of this invention after being assembled into a coin cell. Detailed Implementation

[0031] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings, so that those skilled in the art can better understand the advantages and features of the present invention, thereby making a clearer definition of the scope of protection of the present invention. The embodiments described in this invention are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0032] Example 1:

[0033] A recycled NCM811 cathode material is prepared according to the following steps:

[0034] (1) The waste battery black powder was calcined at 500 °C for 5 hours to remove impurities such as carbon and PVDF binder.

[0035] (2) The pretreated black powder was dissolved in 1.0 M sulfuric acid solution at 65 °C. The solid-liquid ratio of battery black powder to sulfuric acid solution was 20 g / L, resulting in a solution rich in metal elements.

[0036] (3) Remove impurities such as copper, iron, aluminum, calcium and magnesium from the solution.

[0037] (4) The ratio of transition metals nickel, cobalt and manganese was adjusted to 8:1:1 using metal sulfates, and the transition metal elements were precipitated using sodium hydroxide at pH 11.2 to obtain transition metal hydroxides.

[0038] (5) The transition metal hydroxide was added to a 0.5 M oxalic acid solution and reacted at 60 °C for 60 min. The solid-liquid ratio of nickel cobalt manganese hydroxide to oxalic acid solution was controlled at 20 g / L to obtain transition metal oxalate.

[0039] (6) The transition metal oxalate was mixed evenly with lithium hydroxide in excess of 8%, and then subjected to high-temperature solid-state sintering. Specifically, the temperature was raised from room temperature to 500 °C and held for 4 hours, followed by raising the temperature to 800 °C and holding for 12 hours, with a heating rate of 5 °C / min. After natural cooling, the material was taken out and thoroughly ground to obtain the regenerated NCM811 cathode material. The SEM image of the regenerated NCM811 is shown below. Figure 1 As shown.

[0040] The recycled NCM811 was used in lithium-ion batteries, with lithium metal sheets as the negative electrode, PP separators, and CR2032 coin cells assembled. The charge-discharge performance at 1.0 C was measured. Figure 2 As shown, it exhibits superior performance compared to the commercial NCM811.

[0041] Example 2:

[0042] A recycled NCM811 cathode material is prepared according to the following steps:

[0043] (1) The waste battery black powder was calcined at 650 °C for 5 hours to remove impurities such as carbon and PVDF binder.

[0044] (2) Dissolve the pretreated black powder with 2.0 M sulfuric acid solution to obtain a solution rich in metal elements.

[0045] (3) Remove impurities such as copper, iron, aluminum, calcium and magnesium from the solution.

[0046] (4) The ratio of transition metals nickel, cobalt and manganese was adjusted to 8:1:1 using metal sulfates, and the transition metal elements were precipitated using sodium hydroxide at pH 13.0 to obtain transition metal hydroxides.

[0047] (5) The transition metal hydroxide was added to a 0.5 M oxalic acid solution and reacted at 60 °C for 60 min. The solid-liquid ratio of nickel cobalt manganese hydroxide to oxalic acid solution was controlled at 20 g / L to obtain transition metal oxalate.

[0048] (6) The transition metal oxalate was mixed evenly with lithium carbonate in excess of 8%, and then high-temperature solid-state sintering was carried out. Specifically, the temperature was raised from room temperature to 500 °C and held for 4 hours, and then raised to 850 °C and held for 12 hours. The heating rate was 5 °C / min. After natural cooling, the material was taken out and thoroughly ground to obtain the regenerated NCM811 cathode material.

[0049] Comparison Case 1:

[0050] A recycled NCM811 cathode material is prepared according to the following steps:

[0051] (1) The waste battery black powder was calcined at 600 °C for 5 hours to remove impurities such as carbon and PVDF binder.

[0052] (2) Use 2.0 M sulfuric acid to dissolve the pretreated black powder at 65 °C to obtain a solution rich in metal elements.

[0053] (3) Remove undissolved impurities by filtration.

[0054] (4) Nitrogen or argon inert gas is continuously introduced into a 50 L continuous stirred reactor. At the same time, 2 mol / L NaOH precipitant solution and 1.67 mol / L NH3·H2O complexing agent solution are pumped into the reactor by a peristaltic pump (flow rate is 10 ml / min).

[0055] (5) The pH value was kept stable between 11 and 11.5 by controlling the amount of NaOH and NH3·H2O added. The reaction temperature was 60℃, the stirring speed was 500 rpm / min, and the reaction time was 5 h. Then, the precursor material was stirred and aged for 4 h without feeding. The obtained precursor material was then repeatedly washed with deionized water until the pH value of the filtrate was neutral.

[0056] (6) The precursor material and LiOH·H2O lithium salt are mixed evenly in a mortar at a molar ratio of 1:1.065, placed in a corundum crucible, and calcined at high temperature in a tube furnace under an oxygen atmosphere. The sintering procedure is to first calcine at a low temperature of 500℃ for 3 hours, then continuously raise the temperature to 750℃, and hold at this temperature for 12 hours.

[0057] Comparison Case 2:

[0058] A recycled NCM811 cathode material is prepared according to the following steps:

[0059] (1) The waste battery black powder was calcined at 650 °C for 5 hours to remove impurities such as carbon and PVDF binder.

[0060] (2) Dissolve the pretreated black powder in 2.5M acetic acid at 75 °C to obtain a solution rich in metal elements.

[0061] (3) Remove undissolved impurities by filtration.

[0062] (4) Nitrogen or argon inert gas is continuously introduced into a 50 L continuous stirred reactor. At the same time, 2 mol / L NaOH precipitant solution and 1.67 mol / L NH3·H2O complexing agent solution are pumped into the reactor by a peristaltic pump (flow rate is 20 ml / min).

[0063] (5) The pH value was kept stable between 11 and 11.5 by controlling the amount of NaOH and NH3·H2O added. The reaction temperature was 60℃, the stirring speed was 500 rpm / min, and the reaction time was 7 h. Then, the precursor material was stirred and aged for 5 h without feeding. The obtained precursor material was then repeatedly washed with deionized water until the pH value of the filtrate was neutral.

[0064] (6) The precursor material and LiOH·H2O lithium salt are mixed evenly in a mortar at a molar ratio of 1:1.065, placed in a corundum crucible, and calcined at high temperature in a tube furnace under an oxygen atmosphere. The sintering procedure is to first calcine at a low temperature of 500℃ for 3 hours, then continuously raise the temperature to 750℃, and hold at this temperature for 12 hours.

[0065] Table 1 shows a comparison of the final fluorine content and electrochemical performance of the examples and comparative examples. As can be seen from Table 1, Example 1 can obtain in-situ fluorine-doped single-crystal ternary cathode material, and its capacity is increased by 11.5% compared with the traditional recovery method. That is, the present invention can efficiently recover Ni, Co, Mn and Li, and the overall recovery rate can reach more than 90%.

[0066] Table 1

[0067]

[0068] In summary, this invention can efficiently recover Ni, Co, Mn, and Li, with an overall recovery rate exceeding 90%. Simultaneously, it can effectively remove impurities such as Cu, Al, Fe, Ca, and Mg, improving material purity. The resulting single-crystal fluorine-doped regenerated ternary material exhibits excellent cycle stability and rate performance.

[0069] The descriptions and practices disclosed in this invention are readily apparent and understandable to those skilled in the art, and various modifications and refinements can be made without departing from the principles of this invention. Therefore, any modifications or improvements made without departing from the spirit of this invention should also be considered within the scope of protection of this invention.

Claims

1. A method for preparing single-crystal fluorine-doped ternary cathode material using battery black powder, characterized in that, Includes the following steps: Step 1: Calcine the waste battery black powder at high temperature to remove impurities such as carbon and PVDF binder; Step 2: Dissolve the pretreated battery black powder using sulfuric acid solution; Step 3: Remove copper, iron, aluminum, calcium, and magnesium impurities from the battery black powder solution. The specific steps are as follows: Copper was extracted using a 5% organic phase mixture of 984H extractant and sulfonated kerosene. A two-stage countercurrent extraction process was employed. Then, an equimolar ratio of sodium chlorate solution was added, followed by the addition of 2.0 M sodium carbonate solution to adjust the pH to 4.0-4.5 for precipitation to remove iron and aluminum. The slurry after iron and aluminum removal was filtered, and the resulting filtrate was piped to a purification and calcium removal tank. Sodium carbonate was added to remove calcium and magnesium, and the solution was then filtered to obtain a high-purity transition metal solution. Step 4: Precipitate nickel-cobalt-manganese using sodium hydroxide or potassium hydroxide to obtain nickel-cobalt-manganese hydroxide; Step 5: Treat nickel cobalt manganese oxide with oxalic acid solution to obtain nickel cobalt manganese oxalate; Step 6: Lithium replenishment and regeneration of nickel cobalt manganese oxalate, followed by high-temperature sintering to obtain a regenerated ternary cathode material with monocrystalline fluorine doping; Step 7: The remaining waste liquid after filtering nickel cobalt manganese hydroxide in Step 4 is concentrated 20-50 times at 80-95℃, and then a saturated sodium carbonate solution is added at 95℃. The mixture is stirred continuously, and the white solid precipitated is lithium carbonate powder.

2. The method for preparing single-crystal fluorine-doped ternary cathode material using battery black powder according to claim 1, characterized in that, In step 1, the calcination temperature is 500-650°C and the time is 3-5 h.

3. The method for preparing single-crystal fluorine-doped ternary cathode material using battery black powder according to claim 1, characterized in that, In step 2, the sulfuric acid solution can be replaced with hydrochloric acid or nitric acid solution, the reaction temperature is 60-75 °C, the reaction time is 1-4 h, and the solid-liquid ratio of battery black powder to sulfuric acid solution is 20 g / L.

4. The method for preparing single-crystal fluorine-doped ternary cathode material using battery black powder according to claim 1, characterized in that, In step 2, the concentration of the sulfuric acid solution is 1.0-5.

0.

5. The method for preparing single-crystal fluorine-doped ternary cathode material using battery black powder according to claim 1, characterized in that, In step 4, the pH of the reaction extract is controlled between 11.2 and 14. At the same time, the corresponding metal sulfates need to be added to adjust the transition metal ratio to nickel:cobalt:manganese of 1:1:1, 5:2:3, 6:2:2, 8:1:1 or 9:0.5:0.

5.

6. A method for preparing single-crystal fluorine-doped ternary cathode material using battery black powder according to claim 1, characterized in that, In step 5, the concentration of oxalic acid solution is 0.5-2.5M, the reaction temperature is 40-80℃, the reaction time is 1-3h, and the solid-liquid ratio of nickel cobalt manganese hydroxide to oxalic acid solution is 10-30g / L.

7. A method for preparing single-crystal fluorine-doped ternary cathode material using battery black powder according to claim 1, characterized in that, In step 6, the sintering parameters are 500 °C for 4 hours, followed by heating to 800-850 °C and holding for 12 hours, with a heating rate of 5 °C / min.

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