CN115057483B - Method for preparing layered metal hydroxide by recycling high-nickel ternary battery anode material - Google Patents

Abstract

The invention provides a method for preparing layered metal hydroxide by recycling a high-nickel ternary battery anode material. The method comprises the following steps: leaching the high-nickel ternary anode material by using an inorganic acid solution and hydrogen peroxide, and adjusting the pH value to 5-5.5 to obtain a leaching solution; providing a precipitate containing sodium hydroxide and sodium carbonate, wherein the molar concentration of the sodium hydroxide is 1.5-2.5 times of the sum of theoretical leaching values of nickel, cobalt and manganese ions, and the molar concentration of the sodium carbonate is 1.6-2.5 times of the sum of theoretical leaching values of cobalt and manganese ions; the leaching solution is contacted with the precipitation solution, and nucleation-oxidation coupling strengthening reaction is carried out in a micro-liquid membrane reactor with the rotating speed of more than 4000rpm, so as to obtain reaction solution; filtering to obtain solid phase NiCoMn-LDHs and filtrate, and recovering lithium ion in the filtrate over 98%. The method realizes the high-efficiency separation and recovery of nickel, cobalt and manganese and lithium, and the content of nickel, cobalt and manganese in the liquid phase can meet the I-class water quality requirement.

Description

Method for preparing layered metal hydroxide by recycling high-nickel ternary battery cathode material

technical field

The invention belongs to the technical field of recovery and regeneration of positive electrode materials of waste ternary high-nickel lithium-ion batteries, and in particular relates to a method for preparing layered metal hydroxides by recycling high-nickel ternary battery positive electrode materials.

Background technique

The high energy density (180-250Wh kg ^-1 ) and power density (800-1500W kg ^-1 ) of lithium-ion batteries (LIBs) make them the mainstream of the market, and they are used in electric vehicles, digital 3C products, battery energy storage and other fields. , It is estimated that the total shipment of lithium-ion batteries will reach 439.32GWh in 2025. Statistics show that by 2025, the number of electric passenger vehicles is expected to exceed 100 million, and the amount of LIBs scrapped will exceed 44GWh. Ternary materials have comprehensive multi-dimensional advantages and broad development prospects, and have become the mainstream choice for power batteries. In the context of increasing demand for battery energy density, high-nickel ternary cathodes with a nickel content of more than 80% have great advantages in energy density and material cost, and have become a vigorous development trend.

Discarded lithium-ion batteries have many potential hazards, among which heavy metal pollution such as nickel, cobalt, and manganese has brought serious pressure to human health and the environment. In addition, nickel-rich ternary cathode materials are important sources of key metals such as Co (1.5–7.2 wt%), Li (7.1–7.2 wt%), Ni (46.0–57.2%), and Mn (1.4–6.1%). Facing the expansion of the LIBs market, the efficient recovery and reuse of waste LIBs is not only of great environmental significance, but also has significant circular economic benefits.

In recent years, the hydrometallurgical regeneration of waste ternary cathode materials has been widely concerned by researchers, because of its shorter closed-loop recycling process, high resource recovery and utilization rate and high cost-effectiveness, it is considered to be ideal for recycling spent lithium-ion batteries. method. The hydrometallurgical recovery and regeneration process includes the steps of pretreatment, leaching, and regeneration of the positive electrode material precursor. Hydrometallurgical recovery reduces, dissolves and leaches the main body such as nickel, cobalt, and manganese in the pretreated positive electrode material to exist in the solution in the form of divalent metal cations. The main elements of ternary cathode materials (such as Ni, Co, Al or Ni, Co, Mn) do not need to be separated after leaching. After nickel-cobalt-manganese co-precipitation, a ternary material precursor is obtained, while lithium remains in the liquid phase and can be further advanced to prepare lithium carbonate, which can be directly used to produce LIB cathode materials. Chinese Patent Publication No. CN 111960480 A generates a ternary nickel-cobalt-manganese mixed hydroxide precipitation precursor by adding sodium hydroxide solution and ammonia water to a salt solution. However, there is an order-of-magnitude difference in the precipitation-dissolution equilibrium constants between Ni, Co, and Mn. Therefore, there is a problem of nickel, cobalt and manganese precipitation before and after, which leads to the uneven distribution of nickel, cobalt and manganese in the recycled ternary material, which affects the electrochemical performance and cycle stability of the recycled material. Chinese Patent Publication No. CN112239232 A uses inorganic acid H2SO4 solution and hydrogen peroxide to leach positive electrode materials to obtain leaching solution; uses sodium hydroxide alkali solution to control the pH value to remove impurities, and obtains impurity removal liquid; in particular, adopts cyclic leaching and impurity removal processes to improve The concentration of Ni, Co, Mn and other ions in the liquid; use inorganic salts, ammonia water and sodium hydroxide dynamically added to Ni, Co, Mn and other ions as complexing agents to adjust the pH value and metal ion concentration of the mother liquid, and precipitate to prepare ternary positive electrode materials Precursor. However, due to the competition between the ammonia water complexation reaction and the precipitation reaction, it is difficult to completely precipitate nickel, cobalt and manganese, which may cause secondary pollution. The national battery industry pollutant discharge standard (GB/T 30484) requires that the cobalt limit in the water pollution discharge of new enterprises should be less than 0.1mg/L. The national standard for the discharge of pollutants from the inorganic chemical industry (GB/T 31573) requires that the limits of nickel and manganese in water pollution discharge be less than 0.5mg/L and 1mg/L, respectively. At the same time, because battery-grade lithium carbonate has high requirements for purity (>99.5%). Therefore, further reducing the content of nickel, cobalt and manganese after precipitation and separation is not only beneficial to environmental protection, reducing secondary pollution, and reducing the recovery loss of nickel, cobalt and manganese resources, but also beneficial to the next step of recycling lithium resources.

Layered dihydroxyl complex metal hydroxides (LDHs) are compounds formed by the orderly assembly of interlayer anions and positively charged laminates. The main layer is composed of M ²⁺ (OH) ₆ octahedron and M ³⁺ (OH) ₆ octahedron evenly distributed and shared edges, and the molar ratio x value of two and trivalent metal ions in the layer (x=M ³⁺ / (M ²⁺ +M ³⁺ )) in the range of 0.2-0.33, because the composition (the type and ratio of metal ions on the laminate, the type of anion, etc.) is easy to adjust, and the structure (number of layers, layer spacing, etc.) is easy LDHs have good application prospects in electrocatalysis, supercapacitors, secondary batteries, electrochemical energy storage, adsorption, functional additives, medicine and other fields (two-dimensional Nanocomposite Hydroxide: Structure, Assembly and Function, edited by Duan Xue et al., Beijing: Science Press, 2013). The unique advantages of the LDHs laminate structure are expected to solve the above problems: each metal ion on the LDHs laminate is connected to six OH to form an M(OH) ₆ octahedron, which can greatly promote the precipitation of metal ions, so that the solubility of LDHs The product constant (Ksp) is tens of orders of magnitude smaller than that of the corresponding hydroxide. M ²⁺ (OH) ₆ octahedrons and M ³⁺ (OH) ₆ octahedrons are arranged in an orderly manner to form the main layer plate, which is conducive to the uniform distribution of nickel, cobalt and manganese elements. Therefore, taking advantage of the advantages of LDHs is conducive to the efficient reaction and separation of nickel, cobalt, manganese and lithium, to promote the efficient recovery of energy metals, to prevent secondary pollution of heavy metals, and to achieve green emissions.

In the recovery process of ternary materials, nickel, cobalt, and manganese elements exist in the form of divalent metal cations in the solution after leaching, but the preparation of LDHs requires the participation of trivalent metal ions. According to thermodynamic calculations, under alkaline conditions, Co ²⁺ and Mn ²⁺ will be oxidized spontaneously by air, while Ni ²⁺ is difficult to be oxidized spontaneously. Therefore, it is more difficult to recover and prepare LDHs with the increase of nickel content in NCM. For nickel content exceeding 80%, such as LiNi _0.8 Co _0.1 Mn _0.1 , LiNi _0.9 Co _0.05 Mn _0.05 , LiNi _0.95 Co _0.025 Mn _0.025 , etc., due to the high nickel content, it is difficult to regenerate LDHs by spontaneous air oxidation , it is necessary to take additional chemical strengthening means to strengthen the oxidation of enough divalent metal ions to trivalent during the crystal nucleus formation process of LDHs. Therefore, the recovery method of ternary cathode materials with high nickel content needs to be further improved.

Contents of the invention

With the pursuit of energy density in the new energy automobile industry, the nickel content in ternary materials has been continuously increased. At present, high-nickel ternary materials with nickel content accounting for more than 80% of the total nickel, cobalt and manganese have been vigorously developed. However, the preparation of LDHs requires the participation of about 33% trivalent ions, so high-nickel ternary lithium-ion batteries cannot regenerate LDHs with a single crystal phase only by traditional co-precipitation methods. The object of the present invention is to provide a method for directly recycling waste ternary high-nickel lithium-ion batteries into solid-phase nickel-cobalt-manganese layered metal hydroxides (NiCoMn-LDHs). The invention utilizes nucleation-oxidation coupling technology to realize the regeneration of waste ternary high-nickel (nickel content exceeding 80%) lithium-ion batteries into NiCoMn-LDHs, thereby promoting the uniform distribution of nickel-cobalt-manganese elements, and strengthening the cobalt-nickel-manganese and lithium in the liquid phase The separation of resources further reduces the heavy metal content of cobalt, nickel and manganese in the filtrate and prevents secondary pollution by heavy metals.

Specifically, the present invention provides the following technical solutions:

The first aspect of the present invention provides a method for recovering high-nickel ternary positive electrode materials to prepare layered metal hydroxides, including:

(1) leaching the high-nickel ternary positive electrode material through an inorganic acid solution and hydrogen peroxide, and adjusting the pH value to 5-5.5, so as to obtain a leachate;

(2) provide precipitation liquid, described precipitation liquid comprises sodium hydroxide and sodium carbonate, and the molar concentration of described sodium hydroxide is 1.5～2.5 times of described nickel, cobalt, manganese ion concentration theoretical leaching value sum (precipitation liquid If the concentration of sodium hydroxide increases, the precipitation will generate faster, and the size of the precipitation will be smaller, such as 1.5 times, 2 times, or 2.5 times), the molar concentration of the sodium carbonate is the theoretical leaching of cobalt and manganese ion concentration 1.6～2.5 times of the sum of values (if the concentration of sodium carbonate increases in the precipitation solution, the precipitation will be generated faster and the size of the precipitation will be smaller, for example, it can be 1.6 times, 2 times, or 2.5 times);

(3) contacting the leaching solution with the precipitation solution, and performing a nucleation-oxidation coupling strengthening reaction in a micro-liquid membrane reactor with a rotating speed above 4000rpm, so as to obtain a reaction solution containing LDH crystal nuclei;

(4) Based on the reaction solution, obtain solid-phase nickel-cobalt-manganese layered metal hydroxides (NiCoMn-LDHs) and a filtrate by filtration, and the recovery rate of lithium ions in the filtrate is above 98%.

In step (3), the high shear and high centrifugal force generated in the micron-scale reaction space of the micro-liquid membrane reactor are used to strengthen the gas-liquid mass transfer, and to strengthen the participation of air or oxygen in the metal ion precipitation and nucleation at the same time. The oxidation reaction of divalent nickel, cobalt, and manganese ions is partially oxidized into trivalent ions, and LDH crystal nuclei can be obtained.

According to an embodiment of the present invention, the method for preparing a layered metal hydroxide by recovering a high-nickel ternary positive electrode material described above may further include the following technical features:

According to an embodiment of the present invention, the nickel content of the high-nickel ternary positive electrode material in step (1) is above 80%.

According to an embodiment of the present invention, the inorganic acid solution in step (1) is a sulfuric acid solution, and an alkaline solution is added to adjust the pH to 5-5.5, and the alkaline solution is a sodium hydroxide solution or ammonia water.

According to an embodiment of the present invention, in step (3), the leaching solution and the precipitation solution are respectively subjected to a nucleation-oxidation coupling strengthening reaction in a micro-liquid membrane reactor through a dual-channel inlet, and the leaching solution and the precipitation solution are The feed flow rate ratio is 1:1.

According to an embodiment of the present invention, the time for the nucleation-oxidation coupling strengthening reaction in step (3) is 30-300 seconds, preferably 30-180 seconds, such as 30 seconds, 40 seconds, 50 seconds, 60 seconds, 70 seconds, 80 seconds, 90 seconds, 100 seconds, 110 seconds, 120 seconds, 130 seconds, 140 seconds, 150 seconds, 160 seconds, 170 seconds, or 180 seconds.

According to an embodiment of the present invention, when performing the nucleation-oxidation coupling strengthening reaction in step (3), air or oxygen is blown in, and the flow rate of air or oxygen is 10mL/min-100mL/min, preferably 10mL/min -40mL/min.

According to an embodiment of the present invention, step (4) further includes:

(4-1) Based on the reaction solution, carry out a crystallization reaction at 20-90 degrees Celsius, and obtain a filter cake after filtering and washing;

(4-2) The filter cake is dried to obtain solid-phase NiCoMn-LDHs, and the recovery rate of lithium ions in the filtrate after filtration is above 98%.

According to an embodiment of the present invention, the time for the crystallization reaction in step (4) is not more than 8 hours.

According to an embodiment of the present invention, the drying condition is 6-12 hours at 40-60 degrees Celsius.

The second aspect of the present invention provides a method for recovering high-nickel ternary positive electrode materials to prepare layered metal hydroxides, including:

(1) Leach the high-nickel ternary positive electrode material through sulfuric acid solution and hydrogen peroxide, add an alkaline solution to adjust the pH value to 5-5.5, so as to obtain a leachate, the nickel content of the high-nickel ternary positive electrode material is above 80% ;

(2) Precipitating liquid is provided, and described precipitating liquid comprises sodium hydroxide and sodium carbonate, and the molar concentration of described sodium hydroxide is 1.5-2.5 times of the sum of described nickel, cobalt, manganese ion theoretical leaching value, and described carbonic acid The molar concentration of sodium is 1.6-2.5 times the sum of the theoretical leaching values of cobalt and manganese ions;

(3) Contact the leaching solution with the precipitation solution, and carry out a nucleation-oxidation coupling strengthening reaction in a micro-liquid membrane reactor with a rotating speed above 4000rpm, so as to obtain a reaction solution containing an LDH crystal nucleus, and the nucleation- The oxidation coupling strengthening reaction time is 30-300 seconds;

(4) Based on the reaction solution, carry out crystallization reaction at 20-90 degrees Celsius, filter and wash to obtain filter cake, dry to obtain solid-phase NiCoMn-LDHs, and the recovery rate of lithium ions in the filtrate after filtration is above 98% .

The third aspect of the present invention provides a solid-phase NiCoMn-LDHs obtained according to the method described in the first aspect or the second aspect, wherein the D10 of the solid-phase NiCoMn-LDHs is 1.8-2.2 microns, and the D50 is 3 ～4 microns, D90 is 6.5～8 microns.

The beneficial effects obtained by the present invention are:

The main purpose of the present invention is to provide a method for recovering and regenerating LDHs from high-nickel ternary positive electrode materials of waste lithium-ion batteries. Divalent metal cations are oxidized to directly obtain a large number of LDHs crystal nuclei, and there is only a subsequent crystal nucleation growth process, so that high-nickel ternary materials with a nickel content of more than 80% can be recycled to obtain LDHs. The LDHs product obtained in the present invention has high added value, simple process, and LDHs can be prepared by crystallization at room temperature, and even only requires nucleation without crystallization, which is suitable for large-scale application, and the recovery efficiency of nickel, cobalt, and manganese is high, and the separation of lithium and other heavy metals is realized. Efficient separation and recovery, the content of cobalt, nickel and manganese heavy metals in the separated lithium-containing solution can reach the groundwater quality standard I, and can be directly used to prepare battery-grade lithium carbonate after concentration, which is worthy of popularization and application.

Description of drawings

Fig. 1 is an X-ray diffraction pattern of the recovered and regenerated solid-phase LDHs product provided in Example 1 of the present invention.

Fig. 2 is a scanning electron microscope energy spectrum surface scan element distribution diagram of the recovered and regenerated solid-phase LDHs product provided by Example 1 of the present invention.

Fig. 3 is a scanning electron micrograph of the recovered and regenerated solid-phase LDHs product provided in Example 1 of the present invention.

Fig. 4 is a particle size distribution diagram of the recovered and regenerated solid-phase LDHs product provided in Example 1 of the present invention.

Fig. 5 is a linear sweep voltammogram of the recovered and regenerated solid-phase LDHs product provided by Example 1 of the present invention.

Fig. 6 is a graph of the chronocurrent density of the recovered and regenerated solid-phase LDHs product according to Example 1 of the present invention.

Fig. 7 is the X-ray photoelectron spectroscopy and valence state analysis of nickel element in the recovered and regenerated solid phase provided by Example 2 of the present invention.

Fig. 8 is an X-ray diffraction pattern of the recovered solid-phase mixed hydroxide provided in Comparative Example 1 according to the present invention.

Fig. 9 is a scanning electron microscope energy spectrum element distribution diagram of the recovered solid-phase mixed hydroxide provided in Comparative Example 1 of the present invention.

Fig. 10 is a scanning electron micrograph of the recovered solid-phase mixed hydroxide provided in Comparative Example 1 according to the present invention.

Fig. 11 is a particle size distribution diagram of the recovered solid-phase mixed hydroxide provided in Comparative Example 1 according to the present invention.

Fig. 12 is a linear sweep voltammogram of the recovered solid-phase mixed hydroxide provided in Comparative Example 1 according to the present invention.

Fig. 13 is a graph of the chronocurrent density of the recovered solid-phase mixed hydroxide provided in Comparative Example 1 of the present invention.

Fig. 14 is the X-ray photoelectron spectroscopy and valence state analysis of recovered nickel element in the solid phase provided by Comparative Example 2 of the present invention.

Detailed ways

The technical solutions of the present invention will be described in detail below in conjunction with specific examples. At the same time, in order to facilitate the understanding of those skilled in the art, some terms of the present invention are explained and illustrated. It should be noted that these explanations and illustrations are only used to facilitate the understanding of those skilled in the art, and should not be regarded as protection of the present invention. Scope limitation.

Herein, D10 represents the particle size corresponding to when the particle size distribution number reaches 10%, and its physical meaning is that the particles whose particle size is smaller (or larger) account for 10%. D50 represents the particle size corresponding to when the cumulative particle size distribution percentage of a sample reaches 50%. Its physical meaning is that the particles with a particle size larger than it account for 50%, and the particles smaller than it also account for 50%. D50 is also called the median diameter or Median particle size. D90 represents the particle size corresponding to when the cumulative particle size distribution number of a sample reaches 90%. Its physical meaning is that the particles whose particle size is smaller (or larger) account for 90%.

The invention provides a method for preparing a layered metal hydroxide by recovering a high-nickel ternary positive electrode material. The invention strengthens the oxidation of divalent nickel, cobalt and manganese through nucleation-oxidation coupling technology, and at the same time obtains enough trivalent ions to nucleate LDHs. Directly regenerated into solid-phase nickel-cobalt-manganese layered metal hydroxide (NiCoMn-LDH) as a high-value add-on product-oxygen evolution reaction (OER) electrocatalyst, realizing the efficient separation and recovery of nickel-cobalt-manganese and lithium, and The method in which the content of nickel, cobalt and manganese in the liquid phase can meet Class I water quality requirements (National Standard of the People's Republic of China, Groundwater Quality Standard, GB/T 14848-9) and the recovery rate of lithium exceeds 98%.

The invention provides a method for recovering high-nickel ternary positive electrode materials to prepare layered metal hydroxides, comprising: (1) leaching the high-nickel ternary positive electrode materials through inorganic acid solution and hydrogen peroxide, adding alkaline solution to adjust The pH value is 5～5.5, so that obtain leaching liquid; (2) provide precipitating liquid, described precipitating liquid comprises sodium hydroxide and sodium carbonate, and the molar concentration of described sodium hydroxide is nickel, cobalt, between the theoretical leaching value of manganese ion concentration and 1.5-2.5 times, the molar concentration of the sodium carbonate is 1.6-2.5 times of the theoretical leaching value sum of the cobalt and manganese ion concentrations; (3) the leachate is contacted with the precipitation solution, at a speed of more than 4000rmp Nucleation-oxidation coupling strengthening reaction is carried out in the micro-liquid membrane reactor, in order to obtain the reaction solution containing LDH crystal nuclei; (4) Based on the reaction solution, filter to obtain solid-phase NiCoMn-LDHs and filtrate, lithium in the filtrate The recovery rate of ions is above 98%. The present invention recovers high-nickel ternary materials and prepares them into NiCoMn-LDHs products through the nucleation-oxidation coupling technology, which can be used as a high-value add-on product-oxygen evolution reaction (OER) electrocatalyst, and simultaneously realize nickel, cobalt, manganese and lithium elements Reaction-separation coupled approach for efficient recovery. Moreover, the obtained solid-phase NiCoMn-LDHs has a uniform particle size and almost no agglomeration phenomenon, and can also be used as a functional material, such as an oxygen evolution reaction electrocatalyst for electrolyzing water to produce hydrogen. The heavy metal content of nickel, cobalt and manganese in the filtrate can reach the groundwater quality standard I (National Standard of the People's Republic of China, GB/T 14848-9), which is equivalent to the natural background content of the chemical components of the groundwater. The lithium-rich solution obtained by concentrating the filtrate more than 10 times can be directly used to prepare lithium carbonate products. It should be noted that step (1) and step (2) are not used to represent the sequence. In actual operation, the leaching solution can be prepared first, the precipitation solution can also be prepared first, or both can be prepared at the same time.

According to a specific embodiment, the nickel content of the high-nickel ternary positive electrode material in step (1) is above 80%.

According to a specific embodiment, the inorganic acid solution in step (1) is a sulfuric acid solution, and the alkaline solution is a sodium hydroxide solution or ammonia water. Impurities such as aluminum and iron can be effectively removed by adjusting the pH value with an alkaline solution such as sodium hydroxide solution or ammonia water. During use, ammonia water is weak in alkalinity, needs to be used in a large amount, and has a pungent smell. Therefore, ammonia water with a higher concentration is usually not selected.

According to the specific implementation, in step (3), the leachate and the precipitation liquid are respectively carried out in the micro-liquid membrane reactor through the double-channel inlet to strengthen the nucleation oxidation, and the feed flow rate ratio of the leachate and the precipitation liquid is 1:1.

According to a specific embodiment, the time for the nucleation-oxidation coupling strengthening reaction in step (3) is 30-180 seconds. The time of nucleation-oxidation coupling strengthening reaction is prolonged, the oxidation reaction is more sufficient, the content of trivalent ions of nickel, cobalt, and manganese will increase, and the original divalent nickel, cobalt, and manganese ions in the solution are oxidized to more trivalent ions, However, it does not affect the precipitation of NiCoMn-LDH, but the ratio of divalent ions to trivalent ions in NiCoMn-LDH has an appropriate change. Therefore, the reaction time should not be too long. According to a specific embodiment, the time for the nucleation-oxidation coupling strengthening reaction in step (3) is 60 seconds.

According to a specific embodiment, in step (3), when performing the nucleation-oxidation coupling strengthening reaction, air or oxygen is blown in. The micro-liquid membrane reactor is in an open system, or an external pump can be used to blow in air or oxygen. Oxygen can be quickly drawn into the internal flow field of the micro-liquid membrane reactor to generate a large number of bubbles, which can greatly enhance the nucleation of the micro-liquid film. Enhancing gas-liquid mass transfer, oxygen is quickly transferred in the flow field, and the divalent cobalt, nickel, and manganese are rapidly oxidized to obtain enough trivalent ions to participate in the nucleation of LDHs, so as to realize the nucleation-oxidation coupling effect and directly obtain a large number of LDHs crystal nucleus. According to a specific embodiment, the flow rate of air or oxygen is 10mL/min-100mL/min, such as 10mL/min, 20mL/min, 30mL/min, 40mL/min, 50mL/min, 60mL/min, 70mL/min, 80mL /min, 90mL/min, 100mL/min.

According to a specific embodiment, step (4) further includes: (4-1) performing crystallization reaction at 20-90 degrees Celsius based on the reaction solution, and obtaining a filter cake after filtering and washing; (4-2) The filter cake is dried to obtain solid-phase NiCoMn-LDHs, and the recovery rate of lithium ions in the filtrate after filtration is above 98%. Within a certain temperature range, increasing the crystallization temperature will result in more sufficient crystal growth, and NiCoMn-LDH products with better crystallinity and more complete crystal form can be obtained. According to a preferred embodiment, the temperature of the crystallization reaction is 60-80 degrees Celsius.

According to a specific embodiment, the time for the crystallization reaction in step (4) is 1-8 hours. Prolonging the crystallization time, the crystal growth is more sufficient, and the NiCoMn-LDH product with better crystallinity can be obtained, and the crystal form is more complete. According to a preferred embodiment, the time for the crystallization reaction is 2-6 hours.

According to a specific embodiment, the drying condition is drying at 40-60 degrees Celsius for 6-12 hours.

The nickel content in the high-nickel ternary cathode materials mentioned in this article exceeds 80%, including but not limited to: LiNi _0.8 Co _0.1 Mn _0.1 , LiNi _0.9 Co _0.05 Mn _0.05 , LiNi _0.95 Co _0.025 Mn _0.025 and so on.

Example 1

Embodiment 1 provides a method for preparing layered metal hydroxides by reclaiming high-nickel ternary positive electrode materials, including the following steps:

(1) Using 1 L of _a mixed solution with a concentration of 1mol/L _H2SO4 and 1vol% _H2O2 as a leaching agent, 40g of LiNi _0.8 Co _0.1 Mn _0.1 was leached at 40° _C for 2h, and titrated to pH 5.0 by adding NaOH to remove Cu, Metal impurities such as Al obtain solution A;

(2) Solution B of sodium hydroxide and sodium carbonate of configuration 1L, sodium hydroxide molar concentration is cobalt, nickel, manganese ion concentration theoretical leaching value (according to the theoretical molar weight of nickel ion, cobalt ion, manganese ion in solution A Calculate, according to 2 times of the sum of the theoretical leaching value 100% calculation), the molar concentration of sodium carbonate is 2 times of the sum of the theoretical leaching value of cobalt and manganese ion concentration (according to the theoretical leaching 100% calculation);

(3) In an open system, the solution A and the precipitation solution B are simultaneously added to the micro-liquid membrane reactor to strengthen the nucleation-oxidation coupling, the rotor speed is 5000rpm, and the nucleation time is 60s. After the end, the crystal nucleus solution C is collected.

(4) The crystal nucleus solution C obtained in step (3) was placed in a crystallization reactor for crystal growth, and after crystallization at 80° C. for 8 hours, filtered and washed to obtain a filter cake and a filtrate. Wash with deionized water to pH around 9. After drying the solid phase at 50°C for 8 hours, the nickel-cobalt-manganese layered hydroxide that can be obtained has a uniform distribution of nickel, cobalt and manganese at the atomic level, uniform particle size, and almost no agglomeration. Its D ₁₀ is 2.064 μm, D ₅₀ is 3.885 μm, D ₉₀ is 6.975 μm, and the span is 1.264, and it can be used as an electrocatalyst for oxygen evolution reaction. When the current density is 10mA cm ^-2 , the overpotential is 369mV. The attenuation ratio of the current density is 4.36% after the constant overpotential 0.369V detects the timing current density for 5400s.

(5) The recovery rate of lithium in the filtrate phase obtained in step (4) (500 mL equivalent volume) was 98.1%. The nickel content is 3.990ppb, the cobalt content is 3.209ppb, and the manganese content is 3.925ppb. The content of nickel, cobalt and manganese meets the requirements of Class I water quality (National Standard of the People's Republic of China, Groundwater Quality Standard GB/T 14848-9), which is equivalent to the natural chemical composition of groundwater. Low background content.

X-ray diffraction technique is an analytical method to obtain the crystal structure of solid substances. Fig. 1 is an X-ray diffraction pattern of the recovered and regenerated solid-phase LDHs product provided in Example 1 of the present invention. Compared with the standard card, the result shows that the obtained solid phase is LDHs crystal structure without impurity phase.

Scanning electron microscope technology is used to observe the shape of the product, and the energy spectrum surface scan element distribution is used to obtain the distribution of each element in the product, so as to obtain whether the elements are evenly dispersed in the product. Fig. 2 is a scanning electron microscope energy spectrum surface scan element distribution diagram of the recovered and regenerated solid-phase LDHs product provided by Example 1 of the present invention. The results show that the nickel, cobalt, and manganese elements in the LDHs products obtained by the nucleation-oxidation coupling strengthening reaction technology are evenly distributed, which proves the advantages of this technology.

Scanning electron microscopy is used to observe the product morphology. Fig. 3 is a scanning electron micrograph of the recovered and regenerated solid-phase LDHs product provided in Example 1 of the present invention. This result shows that the particle size of LDHs product is smaller and uniform, which is significantly smaller than that obtained by using a stirred reactor.

The particle size distribution diagram obtained by laser particle size analyzer is an analytical technique that reflects the secondary particle size of solid particles. Fig. 4 is a particle size distribution diagram of the recovered and regenerated solid-phase LDHs product provided in Example 1 of the present invention. This result shows that the particle size distribution of solid-phase LDHs products is narrow, which is also a proof of uniform particle size.

Fig. 5 is a linear sweep voltammogram of the recovered and regenerated solid-phase LDHs product provided by Example 1 of the present invention. Linear sweep voltammetry is an electrochemical analysis method. The results indicate that the regenerated solid-phase LDHs product has a low oxygen evolution reaction overpotential and a large current density, and has excellent electrochemical oxygen evolution performance.

Fig. 6 is a graph of the chronocurrent density of the recovered and regenerated solid-phase LDHs product provided in Example 1 of the present invention. The current density curve is an analysis method to reflect the stability of electrode materials. The results show that the regenerated solid-phase LDHs product has good electrochemical oxygen evolution stability, and at a current density of 10 mA/cm2, it operates for more than 5000 seconds, and the current density drops by less than 4.5%.

Example 2

Embodiment 2 provides a method for preparing layered metal hydroxides by reclaiming high-nickel ternary positive electrode materials, including the following steps:

(1) Leach 40 g of LiNi _0.8 Co _0.1 Mn _0.1 at 40 °C for 2 h using 1 L of a mixed solution with a concentration of 1 mol/L H ₂ SO ₄ and 1 vol% H ₂ O ₂ as a leaching agent, and remove Cu by adding NaOH to titrate to pH 5.0, Metal impurities such as Al, obtain solution A;

(2) Configure 1L of mixed solution B of sodium hydroxide and sodium carbonate, and the molar concentration of sodium hydroxide is the theoretical leaching value of cobalt, nickel, and manganese ion concentrations (according to the theoretical molar values of nickel ions, cobalt ions, and manganese ions in solution A 2 times of the sum of the theoretical leaching values (calculated according to the theoretical leaching value of 100%), and the molar concentration of sodium carbonate is 2 times of the sum of the theoretical leaching values of cobalt and manganese ion concentrations (calculated according to the theoretical leaching of 100%);

(3) Add the solution A and the precipitation solution B to the micro-liquid membrane reactor at the same time to nucleate, blow in air, the rotor speed of the colloid mill is 4000rpm, and the nucleation time is 60s. After the end, the crystal nucleus solution C is collected.

(4) The crystal nucleus solution C does not need to be crystallized, and is filtered and washed with a 0.22 μm membrane. Wash with deionized water to pH around 9. The nickel-cobalt-manganese layered hydroxide material was obtained after the solid phase was dried at 50°C for 8 hours. Through XPS fitting analysis, the content of Ni ³⁺ in the solid phase product was 29.09%.

(5) The recovery rate of lithium in the filtrate phase (equivalent volume is 500mL) is 97.8%. The nickel content is 7.349ppb, the cobalt content is 5.592ppb, and the manganese content is 9.504ppb. The nickel, cobalt and manganese content meets the requirements of Class II water quality (National Standard of the People's Republic of China, Groundwater Quality Standard, GB/T 14848-9), which is equivalent to the chemical composition of groundwater. Naturally low background content.

Fig. 7 is the X-ray photoelectron spectroscopy and valence state analysis of nickel element in the recovered and regenerated solid phase provided by Example 2 of the present invention.

Example 3

Embodiment 3 provides a method for preparing layered metal hydroxides by reclaiming high-nickel ternary positive electrode materials, including the following steps:

(1) Using 1 L of _a mixed solution with _a concentration of 1mol/L _H2SO4 and 1vol% _H2O2 as a leaching agent, leaching 40g of LiNi _0.9 Co _0.05 Mn _0.05 at 40°C for 2h, removing Cu by adding NaOH and titrating to pH 5.0, Metal impurities such as Al get solution A;

(2) Configure 1L of mixed solution B of sodium hydroxide and sodium carbonate, the molar concentration of sodium hydroxide is 2 times of the sum of the concentration of cobalt, nickel and manganese element for 100% theoretical leaching, and the molar concentration of sodium carbonate is 100% for theoretical leaching 2 times the sum of the concentration of cobalt and manganese elements;

(3) Use a pump to blow air (40mL/min) into the micro-liquid membrane reactor, add the simulated leaching solution A and the precipitation solution B into the micro-liquid membrane reactor at the same time to strengthen the nucleation-oxidation coupling, and the rotor speed is 5000rpm. The nucleation time is 60s, and the crystal nucleation solution C is collected after the end.

(4) The crystal nucleus solution obtained in step (3) is placed in a crystallization reactor for crystal growth, and after crystallization at 80° C. for 8 hours, it is filtered and washed. Wash with deionized water to pH around 9. After drying the solid phase at 50°C for 8 hours, the nickel-cobalt-manganese layered hydroxide that can be obtained has a uniform distribution of nickel, cobalt and manganese at the atomic level, uniform particle size, and almost no agglomeration. Its D10 is 1.864 μm, and its D50 is 3.681 μm, D90 is 7.123 μm, span is 1.429, and can be used as an electrocatalyst for oxygen evolution reaction. When the current density is 10mA cm ^-2 , the overpotential is 373mV.

(5) The recovery rate of lithium in the filtrate phase (equivalent volume is 500mL) is 98.6%. The nickel content is 4.128ppb, the cobalt content is 3.102ppb, and the manganese content is 3.918ppb. The nickel, cobalt and manganese content meets the requirements of Class I water quality (National Standard of the People's Republic of China, Groundwater Quality Standard, GB/T 14848-9), which is equivalent to the chemical composition of groundwater. Naturally low background content.

Example 4

Embodiment 4 provides a method for preparing layered metal hydroxides by reclaiming high-nickel ternary positive electrode materials, including the following steps:

(1) Using 1 _L of _a mixed solution with a concentration of 1mol/L _H2SO4 and 1vol% _H2O2 as a leaching agent, leaching 40g of LiNi _0.95 Co _0.025 Mn _0.025 at 40°C for 2h, removing Cu by adding NaOH and titrating to pH 5.0, Al and other metal impurities to obtain solution A;

(2) Configure 1L of mixed solution B of sodium hydroxide and sodium carbonate, the molar concentration of sodium hydroxide is 2 times of the sum of the concentration of cobalt, nickel and manganese element for 100% theoretical leaching, and the molar concentration of sodium carbonate is 100% for theoretical leaching 2 times the sum of the concentration of cobalt and manganese elements;

(3) Use a pump to blow oxygen (20mL/min) with a purity of 99.995% into the micro-liquid membrane reactor, add solution A and solution B to the micro-liquid membrane reactor at the same time to strengthen the nucleation-oxidation coupling, and the rotor speed 5000rpm, the nucleation time is 60s, and the crystal nucleation solution C is collected after the end.

(4) The crystal nucleus solution C obtained in step (3) is placed in a crystallization reactor for crystal growth, and after crystallization at 80° C. for 8 hours, it is filtered and washed. Wash with deionized water to pH around 9. After drying the solid phase at 50°C for 8 hours, the nickel-cobalt-manganese layered hydroxide that can be obtained has a uniform distribution of nickel, cobalt and manganese at the atomic level, uniform particle size, and almost no agglomeration. Its D10 is 2.101 μm, and its D50 is 3.412 μm, D90 is 7.216 μm, span is 1.499, and can be used as an electrocatalyst for oxygen evolution reaction. When the current density is 10mA cm ^-2 , the overpotential is 370mV.

(5) The recovery rate of lithium in the filtrate phase (equivalent volume is 500mL) is 97.9%. The nickel content is 4.569ppb, the cobalt content is 4.102ppb, and the manganese content is 4.105ppb. The content of nickel, cobalt and manganese meets the requirements of Class I water quality (National Standard of the People's Republic of China, Groundwater Quality Standard, GB/T 14848-9), which is equivalent to the chemical composition of groundwater. Naturally low background content.

Comparative example 1

Comparative Example 1 provides a method for preparing layered metal hydroxides by reclaiming high-nickel ternary positive electrode materials, including the following steps:

(1) Leach 40 g of LiNi _0.8 Co _0.1 Mn _0.1 at 40 °C for 2 h using 1 L of a mixed solution with a concentration of 1 mol/L H ₂ SO ₄ and 1 vol% H ₂ O ₂ as a leaching agent, and remove Cu by adding NaOH to titrate to pH 5.0, Metal impurities such as Al get solution A;

(2) Configure 1L of mixed solution of sodium hydroxide and sodium carbonate as a precipitant, the molar concentration of sodium hydroxide is twice the sum of the concentration of cobalt, nickel and manganese elements that are theoretically leached 100%, and the molar concentration of sodium carbonate is the theoretical leaching 100% 2 times the sum of the concentration of cobalt and manganese;

(3) The leaching solution in step (1) and the precipitating agent configured in step (2) are simultaneously pumped into the stirred reactor for titration nucleation, and the internal pH of the reactor is kept constant at 11 by controlling the flow rate.

(4) Then crystallize at 80° C., filter and wash after 8 hours. Wash the pH to about 9 with deionized water, and dry the solid phase at 50°C for 8 hours. It is impossible to obtain a single crystal phase nickel-cobalt-manganese layered composite metal hydroxide, and a nickel-cobalt-manganese hydroxide mixture product is obtained. The nickel-cobalt-manganese element The distribution is uneven, the agglomeration phenomenon is serious, the D10 is 0.807 μm, the D50 is 3.549 μm, the D90 is 37.895 μm, and the span is 10.451. When the current density is 10mA cm ^-2 , the overpotential is 437mV. The attenuation ratio of the current density is 21.89% after the constant overpotential 0.369V detects the timing current density for 5400s.

(5) The nickel content in the filtrate phase (equivalent volume is 500mL) is 0.5444ppm, the cobalt content is 0.1177ppm, and the manganese content is 4.293ppm, which is difficult to reach the national emission limit. The national battery industry pollutant discharge standard (GB/T 30484) requires that the cobalt limit in the water pollution discharge of new enterprises should be less than 0.1mg/L. The national standard for the discharge of pollutants in the inorganic chemical industry (GB/T31573) requires that the limits of nickel and manganese in water pollution discharge be less than 0.5mg/L and 1mg/L, respectively.

Fig. 8 is an X-ray diffraction pattern of the recovered solid-phase mixed hydroxide provided in Comparative Example 1 according to the present invention.

Fig. 9 is a scanning electron microscope energy spectrum element distribution diagram of the recovered solid-phase mixed hydroxide provided in Comparative Example 1 of the present invention.

Fig. 10 is a scanning electron micrograph of the recovered solid-phase mixed hydroxide provided in Comparative Example 1 according to the present invention.

Fig. 11 is a particle size distribution diagram of the recovered solid-phase mixed hydroxide provided in Comparative Example 1 according to the present invention.

Fig. 12 is a linear sweep voltammogram of the recovered solid-phase mixed hydroxide provided in Comparative Example 1 according to the present invention.

Fig. 13 is a graph of the chronocurrent density of the recovered solid-phase mixed hydroxide provided in Comparative Example 1 of the present invention.

Comparative example 2

Comparative Example 2 provides a method for preparing layered metal hydroxides by reclaiming high-nickel ternary positive electrode materials, including the following steps:

(1) Leach 40 g of LiNi _0.8 Co _0.1 Mn _0.1 at 40 °C for 2 h using 1 L of a mixed solution with a concentration of 1 mol/L H ₂ SO ₄ and 1 vol% H ₂ O ₂ as a leaching agent, and remove Cu by adding NaOH to titrate to pH 5.0, Metal impurities such as Al get solution A;

(2) Configure 1L of mixed solution of sodium hydroxide and sodium carbonate as a precipitant, the molar concentration of sodium hydroxide is twice the sum of the concentration of cobalt, nickel and manganese elements that are theoretically leached 100%, and the molar concentration of sodium carbonate is the theoretical leaching 100% 2 times the sum of the concentration of cobalt and manganese;

(3) The leaching solution in step (1) and the precipitating agent configured in step (2) are simultaneously pumped into the stirred reactor for titration nucleation, and the internal pH of the reactor is kept constant at 11 by controlling the flow rate.

(4) After the titration is completed, filter and wash directly after stirring and mixing evenly. After washing with deionized water to a pH of about 9, and drying the solid phase at 50°C for 8 hours, the nickel-cobalt-manganese layered composite metal hydroxide of a single crystal phase cannot be obtained, and the content of Ni ³⁺ in the solid phase product is 17.99%. Nickel cobalt manganese hydroxide mixture product. When the current density is 10mAcm ^-2 , the overpotential is 487mV. The attenuation ratio of the current density is 30.16% after the constant overpotential 0.369V detects the timing current density for 5400s.

(5) The nickel content in the filtrate phase (equivalent volume is 500mL) is 87.09ppm, the cobalt content is 30.21ppm, and the manganese content is 47.07ppm, which is far below the national emission limit. The national battery industry pollutant discharge standard (GB/T 30484) requires that the cobalt limit in the water pollution discharge of new enterprises should be less than 0.1mg/L. The national standard for the discharge of pollutants in the inorganic chemical industry (GB/T31573) requires that the limits of nickel and manganese in water pollution discharge be less than 0.5mg/L and 1mg/L, respectively.

Fig. 14 is the X-ray photoelectron spectroscopy and valence state analysis of recovered nickel element in the solid phase provided by Comparative Example 2 of the present invention.

Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention, those skilled in the art can make the above-mentioned The embodiments are subject to changes, modifications, substitutions and variations. These changes, modifications, substitutions and variations are also within the protection scope of the present invention.

Claims (9)

1. A method for preparing layered metal hydroxide by recycling high-nickel ternary cathode material, which is characterized by comprising the following steps:

(1) Leaching the high-nickel ternary cathode material by using an inorganic acid solution and hydrogen peroxide, and adjusting the pH value to be 5-5.5 so as to obtain a leaching solution, wherein the nickel content of the high-nickel ternary cathode material in the step (1) is more than 80%;

(2) Providing a precipitation solution, wherein the precipitation solution comprises sodium hydroxide and sodium carbonate, the molar concentration of the sodium hydroxide is 2 times of the sum of theoretical leaching values of nickel, cobalt and manganese ions, and the molar concentration of the sodium carbonate is 2 times of the sum of theoretical leaching values of cobalt and manganese ions;

(3) The leaching solution is contacted with the precipitation solution, air or oxygen is blown into a micro-liquid membrane reactor with the rotating speed of 5000rpm or nucleation-oxidation coupling strengthening reaction is carried out in an open system, so that reaction solution containing LDH crystal nucleus is obtained; wherein the time of the nucleation-oxidation coupling strengthening reaction is 30 seconds to 300 seconds, and the flow rate of the air or the oxygen is 10mL/min to 100mL/min;

(4) Based on the reaction liquid, filtering to obtain solid-phase NiCoMn-LDHs and filtrate, wherein the recovery rate of lithium ions in the filtrate is more than 98%.

2. The method of claim 1, wherein the inorganic acid solution in the step (1) is sulfuric acid solution, and an alkaline solution is added to adjust the pH to 5-5.5, and the alkaline solution is sodium hydroxide solution or ammonia water.

3. The method according to claim 1, wherein in the step (3), the leaching solution and the precipitation solution are subjected to nucleation-oxidation coupling enhancement reaction in a micro-liquid film reactor through a double-channel inlet, and the feed flow rate ratio of the leaching solution to the precipitation solution is 1:1.

4. The method of claim 1, wherein the nucleation-oxidation coupling enhancement reaction in step (3) is performed for a period of 30 seconds to 180 seconds.

5. The method of claim 1, wherein the flow rate of air or oxygen in step (3) is 10mL/min to 40mL/min.

6. The method of claim 1, wherein step (4) further comprises:

(4-1) carrying out crystallization reaction at 20-90 ℃ based on the reaction liquid, and filtering and washing to obtain a filter cake;

(4-2) drying the filter cake so as to obtain solid-phase NiCoMn-LDHs, and recovering the lithium ions in the filtrate after filtration to be more than 98%.

7. The method according to claim 6, wherein the crystallization reaction time in the step (4) is 1 to 8 hours.

8. The method of claim 6, wherein the drying is performed at 40-60 degrees celsius for 6-12 hours.

9. A solid phase NiCoMn-LDHs obtained according to the method of any of claims 1 to 8, wherein the solid phase NiCoMn-LDHs has a D10 of 1.8 to 2.2 microns, a D50 of 3 to 4 microns and a D90 of 6.5 to 8 microns.