A method for recovering valuable metal elements from waste lithium-ion batteries using a mechanical activation method

Abstract

The application discloses a method for recovering valuable metal elements from waste lithium ion batteries by using a mechanical activation method, and comprises the following steps: (1) ball milling a positive active material of the waste lithium ion batteries with a sulfur source to obtain an activation product; and (2) acid leaching the activation product to obtain a sulfur-containing filter residue and a solution containing valuable metals. According to the application, the transition metal elements in the positive active material of the waste lithium ion batteries can be effectively reduced during ball milling, the use of a reducing agent is reduced, the reaction rate is obviously accelerated after activation, the recovery rate of the valuable metals is high, and the use of an acidic solution can be reduced.

Description

Technical Field

[0001] This invention relates to the resource recycling of waste lithium-ion batteries, and more particularly to a method for recovering valuable metal elements from waste lithium-ion batteries using a mechanical activation method. Background Technology

[0002] Lithium-ion batteries, due to their advantages such as high operating voltage, high energy density, and no memory effect, have been widely used in new energy vehicles, mobile phones, computers, and other fields in recent years, leading to a surge in sales. As these batteries reach the end of their service life, they will face a rapid decline in usage. The approaching retirement of power batteries and the constraints of lithium resources make lithium battery recycling imperative. Under the backdrop of carbon neutrality, the electric vehicle and energy storage markets will experience rapid growth. The scarcity of metal resources such as lithium, nickel, cobalt, and manganese in lithium-ion batteries also necessitates the recycling of valuable metals from spent lithium-ion batteries to alleviate the current resource shortage.

[0003] The current mainstream recycling process involves discharging, dismantling, and crushing spent lithium-ion batteries to obtain active materials. These active materials then undergo acid leaching, neutralization to remove impurities, filtration, extraction, lithium precipitation, washing, and drying. This process is lengthy and requires the addition of extra reducing agents, increasing costs. Currently, the mechanochemical method is used to process spent lithium-ion battery cathode materials. Although it has a high leaching rate for valuable metals, it requires the addition of large amounts of reducing agents and activators, resulting in very high costs. Therefore, there is a need to develop a low-cost recycling method with a fast leaching rate.

[0004] The patent document with publication number CN107275706A discloses a method of activating lithium cobalt oxide material in a planetary ball mill, leaching the activated lithium cobalt oxide cathode material in an ascorbic acid solution at room temperature, and extracting lithium and cobalt using traditional methods such as electrodeposition after solid-liquid separation. This method involves adding ascorbic acid, which is a reducing acid and has high cost. Moreover, it is more expensive to process complex cathode materials such as ternary materials than to process them with cheap acids such as sulfuric acid and reducing agents.

[0005] Patent document CN106848469A discloses a method for recovering valuable metals from waste lithium-ion batteries. The method involves mixing and grinding the metals with chloride salts to obtain a mixture, calcining the mixture at high temperature, and then leaching the calcined solid product with water to obtain a salt solution containing valuable metals. This method is energy-intensive for recovering valuable metals and generates chloride-containing gases during the reaction process, resulting in serious environmental impact. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to overcome the deficiencies and defects mentioned in the background art above, and to provide a method for recovering valuable metal elements from waste lithium-ion batteries using mechanical activation.

[0007] To solve the above-mentioned technical problems, the technical solution proposed by this invention is as follows:

[0008] A method for recovering valuable metal elements from spent lithium-ion batteries using mechanical activation includes the following steps:

[0009] (1) The active material of the positive electrode of the waste lithium-ion battery was ball-milled with a sulfur source to obtain the activation product;

[0010] (2) The activated product is acid-leached to obtain sulfur-containing filter residue and a solution containing valuable metals.

[0011] In the above-mentioned method for recovering valuable metal elements from waste lithium-ion batteries using mechanical activation, preferably, the sulfur source is elemental sulfur, and the sulfur source accounts for 20%-30% of the total mass of the active material and the sulfur source.

[0012] In the above-mentioned method for recovering valuable metal elements from waste lithium-ion batteries using mechanical activation, preferably, during the ball milling process, the mass ratio of material to grinding beads is 1:30-1:40, the ball milling speed is 500-870 rpm / min, and the ball milling time is 60-90 min.

[0013] In the above-mentioned method of recovering valuable metal elements from waste lithium-ion batteries using mechanical activation, preferably, one or more of sulfuric acid and hydrochloric acid with an acid concentration of 0.5~2.5 mol / L are selected during the acid leaching process, and the acid leaching time is 30~60 min.

[0014] The preferred method for recovering valuable metal elements from waste lithium-ion batteries using the above-mentioned mechanical activation method involves placing the sulfur-containing filter residue in pure water for ultrasonic dispersion, taking the supernatant, and obtaining elemental sulfur through solid-liquid separation.

[0015] In the above-described method for recovering valuable metal elements from spent lithium-ion batteries using mechanical activation, preferably, the ultrasonic dispersion time is 20-40 minutes.

[0016] In the above-mentioned method of recovering valuable metal elements from waste lithium-ion batteries using mechanical activation, preferably, the positive electrode active material of the waste lithium-ion battery is a powder obtained by discharging, dismantling, calcining, and ball milling the positive electrode material of the lithium-ion battery.

[0017] In the above-described method for recovering valuable metal elements from spent lithium-ion batteries using mechanical activation, preferably, the cathode material of the spent lithium-ion batteries is a cathode material containing at least one of nickel, cobalt, and manganese.

[0018] This invention mixes the active material from waste lithium-ion batteries with a sulfur source. By controlling the amount of sulfur source added and the rotation speed of the ball mill, the activation level of the cathode material is controlled. During ball milling, the high-speed collision and compression between the balls compresses the cathode material and the sulfur source. While grinding the active material, the heat generated by the collision and compression with sulfur also destroys the structure of the cathode material. During the collision and compression process, sulfur also reduces the high-valence transition metal elements in the cathode material. No additional reducing agent is needed in the subsequent acid leaching process, and sulfur does not participate in the acid leaching process. Sulfur can be recycled and reused, realizing the efficient utilization of valuable metals in waste lithium-ion batteries.

[0019] Compared with the prior art, the advantages of the present invention are as follows:

[0020] (1) The present invention can effectively reduce the transition metal elements in the cathode material of waste lithium-ion batteries by mechanical ball milling, thereby reducing the use of reducing agent. After activation, the reaction rate is significantly accelerated, the recovery rate of valuable metals is high, and the use of acidic solution can be reduced.

[0021] (2) In the process of recovering valuable metal elements from waste lithium-ion batteries using mechanical activation, the present invention introduces elemental sulfur as a reducing agent. The elemental sulfur that does not react in mechanical activation can be recycled, and the small amount of sulfate generated by elemental sulfur in the activation process will also reduce the loss in subsequent acid leaching.

[0022] (3) The process for recovering valuable metals from waste lithium-ion battery cathode materials is simple to operate, can effectively avoid secondary pollution, has a short process time, low raw material cost, and is suitable for industrial production. Attached Figure Description

[0023] Figure 1 This is a process flow diagram of the present invention for recovering valuable metal elements from waste lithium-ion batteries using a mechanical activation method.

[0024] Figure 2 This refers to the recovery rate of lithium and cobalt in the waste lithium cobalt oxide cathode material in Example 2 and Comparative Example 1 of this invention. Detailed Implementation

[0025] To facilitate understanding of the present invention, the invention will be described more fully and in detail below with reference to the accompanying drawings and preferred embodiments, but the scope of protection of the present invention is not limited to the following specific embodiments.

[0026] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0027] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0028] Example 1:

[0029] A method for recovering valuable metal elements from spent lithium-ion batteries using mechanical activation according to the present invention is shown in the process flow diagram below. Figure 1 As shown, the specific steps are as follows:

[0030] (1) The waste lithium cobalt oxide positive electrode material is placed in a 120g / L sodium chloride solution for discharge treatment. After the discharge is completed, the waste lithium-ion battery is disassembled to separate the positive electrode, separator, negative electrode, electrolyte and shell. The positive electrode is placed in a muffle furnace for high-temperature roasting to completely separate the active material from the current collector aluminum foil. The separated active material is ball-milled to obtain lithium cobalt oxide positive electrode active powder.

[0031] (2) The lithium cobalt oxide positive electrode active material and elemental sulfur accounting for 20% of the total mass of the active material and elemental sulfur were placed in a ball mill jar, and ball milling media were added. The mass ratio of material to milling beads was 1:30. The active product was activated by ball milling at 870 rpm for 60 min.

[0032] (3) The active product obtained in step (2) was added to a 2 mol / L sulfuric acid solution and leached at 80°C for 60 min. After filtration, lithium cobalt leaching solution and sulfur-containing filter residue were obtained. It was found that the lithium recovery rate in the waste lithium cobalt oxide cathode material could reach 99% and the cobalt recovery rate could reach 83%.

[0033] (4) Add the sulfur-containing filter residue to pure water and sonicate for 20 minutes. Let it settle for 1 hour. Take the surface clear liquid and filter it to obtain unreacted elemental sulfur, which can be reused.

[0034] Example 2:

[0035] This invention discloses a method for recycling valuable metal elements from spent lithium-ion batteries using mechanical activation, the process flow diagram of which is shown below. Figure 1 As shown, the specific steps are as follows:

[0036] (1) Discharge the waste lithium cobalt oxide positive electrode material in a 120g / L sodium chloride solution. After the discharge is completed, disassemble the waste lithium-ion battery and separate the positive electrode, separator, negative electrode, electrolyte and shell. Place the positive electrode in a muffle furnace and bake at high temperature to completely separate the active material from the current collector aluminum foil. Ball mill the separated waste lithium-ion battery positive electrode active material to obtain lithium cobalt oxide active powder.

[0037] (2) The active powder of lithium cobalt oxide and elemental sulfur accounting for 30% of the total mass of active material and elemental sulfur were placed in a ball mill jar, and ball milling media were added. The mass ratio of material to grinding beads was 1:40. The active product was activated by ball milling at 870 rpm for 60 min.

[0038] (3) The active product obtained in step (2) was added to a 2 mol / L sulfuric acid solution and leached at 80°C for 60 min. After filtration, lithium-cobalt leaching solution and sulfur-containing filter residue were obtained. The recovery rates of lithium and cobalt in the waste lithium cobalt oxide cathode material were determined as follows: Figure 2 As shown, the lithium recovery rate can reach 99.59%, and the cobalt recovery rate can reach 89.6%.

[0039] (4) Add the sulfur-containing filter residue to pure water and sonicate for 20 minutes. Let it settle for 1 hour. Take the surface clear liquid and filter it to obtain unreacted elemental sulfur. This elemental sulfur can be reused.

[0040] Comparative Example 1:

[0041] The lithium cobalt oxide active powder prepared in step (1) of Example 2 was directly placed into a ball mill jar (the amount of lithium cobalt oxide active powder was the same as in Example 2, without the addition of elemental sulfur). Then, ball milling media were added, with a material-to-milling-bead mass ratio of 1:40. The mixture was ball-milled at 870 rpm for 60 min. Then, it was added to a 2 mol / L sulfuric acid solution and leached at 80°C for 60 min. Solid-liquid separation was performed to obtain lithium cobalt leaching solution and filter residue. The recovery rates of lithium and cobalt in the waste lithium cobalt oxide cathode material were measured as shown in the figure. Figure 2 As shown, the lithium recovery rate can reach 86%, and the cobalt recovery rate can reach 39.8%.

Claims

1. A method for recovering valuable metal elements from spent lithium-ion batteries using mechanical activation, characterized in that, Includes the following steps: (1) The active material of the positive electrode of the waste lithium-ion battery is ball-milled with a sulfur source to obtain an activation product; the sulfur source is elemental sulfur, and the sulfur source accounts for 20%-30% of the total mass of the active material and the sulfur source; during the ball milling process, the mass ratio of the material to the grinding ball is 1:30-1:40, the ball milling speed is 500~870 rpm / min, and the ball milling time is 60~90 min; (2) The activated product is acid-leached to obtain sulfur-containing filter residue and a solution containing valuable metals.

2. The method for recovering valuable metal elements from spent lithium-ion batteries using mechanical activation as described in claim 1, characterized in that, During the acid leaching process, one or more of sulfuric acid and hydrochloric acid with an acid concentration of 0.5~2.5mol / L are selected, and the acid leaching time is 30~60min. The acid leaching is carried out at room temperature.

3. The method for recovering valuable metal elements from spent lithium-ion batteries using mechanical activation as described in any one of claims 1 to 2, characterized in that, The sulfur-containing filter residue was placed in pure water and ultrasonically dispersed. The supernatant was taken and elemental sulfur was obtained through solid-liquid separation.

4. The method for recovering valuable metal elements from spent lithium-ion batteries using mechanical activation as described in claim 3, characterized in that, The ultrasonic dispersion time is 20-40 minutes.

5. The method for recovering valuable metal elements from spent lithium-ion batteries using mechanical activation as described in any one of claims 1 to 2, characterized in that, The waste lithium-ion battery positive electrode active material is a powder obtained by discharging, dismantling, calcining, and ball milling lithium-ion battery positive electrode materials.

6. The method for recovering valuable metal elements from spent lithium-ion batteries using mechanical activation as described in claim 5, characterized in that, The cathode material of the waste lithium-ion battery is a cathode material containing at least one of nickel, cobalt, and manganese.

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