CN111430829A - Method for recycling and regenerating waste lithium battery anode material under assistance of biomass waste - Google Patents

Abstract

The invention discloses a method for recycling and regenerating a positive electrode material of a waste lithium battery with the assistance of biomass waste, and belongs to the technical field of resource recycling. The invention uses biomass waste as a reducing agent, organically combines the recovery of waste power lithium batteries with the regeneration of ternary positive electrode materials, and realizes the recycling of waste power lithium batteries at low cost; the process flow is short, the synthesis cost is low, and it is suitable for Large-scale production, the regenerated nickel-cobalt-manganese ternary cathode material has excellent performance and good economic and social benefits.

Description

A method for recycling and regenerating cathode materials of waste lithium batteries with the assistance of biomass waste

technical field

The invention belongs to the technical field of resource recycling, and in particular relates to the recovery of positive electrode materials in waste lithium ion batteries and the cyclic preparation of regenerated ternary positive electrode materials.

Background technique

In recent years, with the increasing consumption of fossil fuels and the gradual enhancement of people's awareness of environmental protection, chemical power sources have been widely used as alternative energy sources, especially in the field of electric vehicles. The sharp growth of power lithium batteries has also resulted in the generation of a large number of waste lithium-ion batteries. According to the forecast of the China Automotive Technology Research Center, according to the sales volume of new energy vehicles in 2015, more than 300,000 vehicles and the number of new energy vehicles in 2020 will be about 5 million. It is estimated that by 2020, only the power batteries of hybrid and pure electric (including plug-in) passenger cars in my country will be scrapped cumulatively to 120,000-170,000 tons. Waste power lithium-ion batteries contain high-value metals such as nickel, cobalt, and manganese. Taking certain treatment methods to recycle waste batteries can not only reduce the impact on the environment, but also realize the recycling of resources.

At present, the treatment methods of waste power lithium batteries are basically divided into three aspects: pretreatment, secondary treatment and advanced treatment. The pretreatment is to obtain the positive electrode sheet after discharging, dismantling and sorting; the purpose of the secondary treatment is to realize the separation of the positive electrode active material and the aluminum foil. The main methods are: pyrolysis method, organic solvent separation method, alkali leaching method, etc.; The treatment includes two parts: leaching and separation and purification, mainly to realize the recovery of valuable metals. In the recovery and utilization of valuable metal resources by traditional methods, they are generally recovered separately in the form of metal salts. In the process of metal separation and impurity removal, the process is complicated. , it is easy to produce secondary pollution, and the production cost of recycling is high.

SUMMARY OF THE INVENTION

Aiming at the shortcomings of the traditional process, the technical problem to be solved by the present invention is to provide a method for recycling and regenerating the positive electrode material of a waste lithium battery with the assistance of biomass waste. First, the waste positive electrode powder is reduced and roasted by using the biomass waste; liquid and water leaching slag; the water leaching solution is used to prepare the lithium source; the water leaching slag is obtained by acid leaching to obtain the acid leaching solution; the purified solution after the impurity removal of the acid leaching solution is prepared by fast co-precipitation + hydrothermal method; finally, the precursor is prepared by mixing Lithium calcination is used to prepare a regenerated ternary cathode material in a short calcination time.

In order to achieve the above purpose, the present invention provides a method for recycling and regenerating the positive electrode material of a waste lithium battery with the assistance of biomass waste, comprising the following steps:

The first step: reduction roasting

The biomass and the waste positive electrode powder are subjected to reduction roasting at a temperature of 700-800°C in a protective atmosphere to obtain a reduction roasting material; wherein, the amount of biomass added is 10-30% of the mass of the waste positive electrode powder;

The second step, water immersion

Carry out water immersion with the raw material of the first step to obtain water leaching solution and water leaching slag;

The third step, the preparation of lithium source

Using the water leaching solution obtained in the second step as a raw material, through precipitation, the lithium source is recovered;

The fourth step, pickling

Under the action of the acid system, the water leaching residue obtained in the second step is subjected to acid leaching to obtain an acid leaching solution;

The fifth step, ternary precursor preparation

The acid leaching solution in the fourth step is subjected to impurity removal treatment to obtain a purified solution, and the ratio of nickel, cobalt and manganese in the purified solution is adjusted, and after rapid co-precipitation in advance, a ternary precursor is prepared by hydrothermal reaction;

The sixth step, preparation of ternary cathode material

The ternary precursor in the fifth step and the lithium source obtained in the third step are uniformly ground and then calcined to obtain a new ternary positive electrode material.

The present invention innovatively uses biomass (organic carbon source) as the reducing component, and participates in the reduction roasting of the waste positive electrode powder under the stated conditions. It is found that the use of organic matter to participate in this type of reaction is compared with the existing carbon element. It is a kind of reducing agent, which can unexpectedly facilitate the separation of lithium from the lattice of waste cathode materials, which helps to fundamentally solve the problem of recycling waste cathodes. In addition, with the pre-precipitation of lithium and the rapid co-precipitation and hydrothermal process of nickel-cobalt-manganese described in the present invention, and the subsequent solid calcination of lithium preparation, the crystal phase, morphology, particle size of the recovered cathode material can be effectively improved. and uniformity, the specific capacity and cycle performance of the recovered positive electrode material can be improved and improved, in addition, the present invention can realize full recovery of raw materials, good material regeneration effect and low cost.

The present invention is a method for recycling and regenerating a positive electrode material of a waste lithium battery with the assistance of biomass waste. At least one of lithium oxide, lithium nickel manganate, and lithium nickel cobalt manganate.

The present invention innovatively uses biomass to participate in the reduction and roasting of the waste positive electrode material, and research finds that it is more conducive to the separation of lithium from the lattice of the waste positive electrode material, and is conducive to the separation of elements such as lithium and nickel, cobalt, and manganese.

The biomass reducing agent is an organic carbon source, preferably at least one of corn stover, rapeseed cake, rice husk, rice straw and sorghum distiller's grains. Its particle size is preferably 200 meshes to 300 meshes.

In the present invention, the waste positive electrode powder and the biomass reducing agent are placed in a ball mill-type mixing equipment to be mixed, for example, for 1-2 hours, and then the temperature is raised for reduction and roasting. The study found that further controlling the amount of biomass in the biomass-assisted reduction roasting process and the roasting temperature will help to further improve the effect of lattice separation of lithium from waste cathode materials, and help to improve the subsequent recovery of cathode materials. electrical properties.

Preferably, the temperature of the reduction roasting process is 750-800°C.

Preferably, the reduction roasting time is 1-8h.

Preferably, the amount of biomass added (on a dry weight basis) is 10-30% of the mass of the waste cathode powder; preferably 20-30%.

In the reduction roasting process, the protective gas is, for example, nitrogen or an inert gas.

The invention innovatively reduces and roasts with the aid of biomass, and can realize high-efficiency separation of lithium, nickel, cobalt, manganese and the like by adopting a conventional water leaching process.

It is found that, for the present invention, controlling the solid-liquid ratio in the water leaching process helps to further improve the separation effect of lithium and nickel, cobalt, and manganese.

Preferably, in the water immersion process, the liquid-solid ratio (mL:g) of deionized water and the reduced calcination material is 20:1-100:1; preferably, it is 30-80 mL:g.

The temperature of the water leaching process is 20-60°C, and the time is 0.5h-5h.

Preferably: in the third step, the prepared lithium source is lithium hydroxide or lithium carbonate; wherein, the step of preparing lithium hydroxide is: adding lime to the water leaching solution obtained in the second step and utilizing lithium carbonate causticization method to prepare hydroxide Lithium solid. The steps of preparing lithium carbonate are as follows: adding a carbonizing agent to the water immersion solution, preparing lithium carbonate at 60-90° C. with a reaction time of 1h-5h, the carbonizing agent is sodium carbonate or sodium bicarbonate, and the excess coefficient of the carbonizing agent is 1.05 -3.0.

The present invention is a method for recycling and regenerating a positive electrode material of a waste lithium battery with the assistance of biomass waste. The acid leaching in the fourth step refers to adding the water leaching residue of the second step into a sulfuric acid solution, and fully reacting under stirring, Then filter to obtain acid leaching solution and acid leaching residue; the concentration of sulfuric acid is 1.5-5 mol/L, the acid leaching temperature is 15-95° C., and the liquid-solid ratio is 3:1-5:1.

In the present invention, the impurity removal step is as follows: first, adjust the pH value of the acid leaching solution obtained in the fourth step to 5-6 with 2-5mol/L NaOH solution, hydrolyze to remove aluminum and iron impurities, and then add iodine value higher than 1200 2-3g/L of coconut shell activated carbon is used to remove oil, and after filtration, a purified liquid is obtained.

Then, transition metal salts (such as water-soluble salts of nickel, cobalt, and manganese) are added to the purification solution, and the ratio of nickel, cobalt, and manganese is adjusted arbitrarily.

In the present invention, a rapid co-precipitation + hydrothermal synergistic process is innovatively adopted to obtain a precursor, and then lithium is added for solid-solid roasting. According to the research of the present invention, it is found that the morphology and crystallinity of the obtained positive electrode material can be improved by cooperating with the biomass-assisted roasting process, further cooperating with the rapid co-precipitation + hydrothermal precursor, and the subsequent solid-solid lithium roasting process. The phase and particle size can be used to obtain positive electrode materials with high electrical performance without adding too much analytical grade raw materials.

The study found that controlling the conditions of co-precipitation can help to further improve the effect of the synergistic process.

The rapid co-precipitation process is as follows: using ammonia water with a concentration of 2-6 mol/L and NaOH solution with a concentration of 1-3 mol/L as complexing agent and precipitating agent, adjusting the pH of the solution to 11-12; Precipitation reaction 10-30min.

The rapid co-precipitation reaction system is subjected to a hydrothermal reaction at a temperature of 160-220° C., followed by filtration, washing and drying to obtain a ternary precursor. In the present invention, the system after rapid co-precipitation is placed in an oven at 160-220° C. for hydrothermal reaction for 4-8 hours, and the ternary precursor is obtained by filtration, washing and drying;

The present invention is a method for recycling and regenerating a positive electrode material of a waste lithium battery with the assistance of biomass waste. The preparation of the ternary positive electrode material in the sixth step refers to mixing and grinding the ternary precursor obtained in the fifth step with a lithium source and then placing it in an oxygen atmosphere. Lower roasting to obtain a regenerated ternary positive electrode material LiNi _x Co _y Mn _z O ₂ ; the roasting temperature is 600-1000° C., the roasting time is 4-12 h, and the regenerated ternary positive electrode material is LiNi _1/3 Co _1/3 Mn Any one of _1/3 O ₂ , LiNi _0.5 Co _0.2 Mn _0.3 O ₂ , LiNi _0.6 Co _0.2 Mn _0.2 O ₂ or LiNi _0.8 Co _0.1 Mn _0.1 O ₂ , with a size of 100-300 nm.

In the present invention, the thermal behavior of biomass in the system is beneficial to the selective leaching of lithium and the subsequent recovery of transition metals, and the biomass waste is low in cost and environmentally friendly. In addition, the transition metal needs to be separated separately after leaching in the traditional process. In the present invention, the cathode material is directly synthesized after the waste lithium battery is leached, which effectively simplifies the process flow. The nickel-cobalt-manganese ternary cathode material is widely used because of its low cost and high capacity. The main components of the nickel-cobalt-manganese-based waste cathode material are consistent with the ternary cathode material, which is an ideal regeneration product. Not only that, the existing preparation process of solicited materials is mainly co-precipitation-roasting. For example, if the co-precipitation and aging time reaches about 24 hours, the roasting process is usually pre-calcined at 450-550 ℃ for more than 5 hours and then calcined at 750-950 ℃ for 10 hours. As mentioned above, although the existing conventional process is commercially successful, it has high energy consumption, serious lithium volatilization loss, poor crystal form and serious agglomeration of the obtained cathode material, which affects the yield and its electrochemical performance. The invention innovatively adopts the rapid co-precipitation + hydrothermal combination method to prepare the precursor in advance. The research finds that this process can improve the crystallinity of the precursor and improve the morphology uniformity and particle size by cooperating with the control of various parameters.

The process of the invention resynthesizes the positive electrode material of the lithium ion battery through the steps of biomass-assisted reduction roasting, water immersion, lithium source preparation, acid leaching, precursor synthesis, mixed lithium roasting, etc., which not only shortens the technological process, but also reduces the production cost. It also realizes the recycling and high-value recycling of waste materials.

The present invention provides a method for recycling and regenerating a positive electrode material of a waste lithium battery with the assistance of biomass waste. The method adopts a brand-new process path, and has the following beneficial effects compared with the prior art: using biomass waste in a pyrolysis process The generated reducing substances (CO mixed gas, tar, fixed carbon) can reduce high-priced transition metals in waste lithium batteries, which is conducive to the selective leaching of lithium and subsequent transition metal recovery, and the biomass waste is low in cost and environmentally friendly. ;Lithium is selectively recovered by water leaching to obtain by-products of lithium carbonate and lithium hydroxide; most of the valuable metals are recovered by acid leaching, avoiding waste of resources; the preparation of ternary precursors by rapid co-precipitation + hydrothermal method greatly shortens After shortening the process time, the particle size of the prepared precursor is smaller, which is conducive to lithium ion transport, and the activity of the regenerated ternary cathode material is better; a green process route from waste cathode powder to recycled cathode powder is formulated, and the whole process is simple. It is easy for large-scale production, and realizes the closed-loop cycle of resources and the recycling and high-value utilization of waste.

The invention provides a method for recycling and regenerating positive electrode materials of waste lithium batteries with the assistance of biomass waste. When the positive electrode active material of the waste lithium batteries contains Ni, the recovery rate of Ni is greater than or equal to 96%;

When Co is contained in the positive active material of used lithium batteries, the recovery rate of Co is greater than or equal to 96%;

When Mn is contained in the positive active material of waste lithium batteries, the recovery rate of Mn is greater than or equal to 96%;

In the positive active material of the waste lithium battery, the recovery rate of Li is greater than or equal to 98%.

The invention provides a method for recycling and regenerating the positive electrode material of waste lithium batteries with the assistance of biomass waste. When the regenerated ternary positive electrode material is LiNi _1/3 Co _1/3 Mn _1/3 O ₂ , the initial charge and discharge have a specific capacity of 150-160, cycle 50 times, its specific capacity is 135-145;

When the regenerated ternary cathode material is LiNi _0.5 Co _0.2 Mn _0.3 O ₂ , the specific capacity is 160-170 for the initial charge and discharge, and the specific capacity is 145-155 after 50 cycles;

When the regenerated ternary cathode material is LiNi _0.6 Co _0.2 Mn _0.2 O ₂ , the specific capacity is 165-175 after initial charge and discharge, and the specific capacity is 150-165 after 50 cycles;

When the regenerated ternary positive electrode material is LiNi _0.8 Co _0.1 Mn _0.1 O ₂ , the specific capacity is 175-200 after initial charge and discharge, and the specific capacity is 155-180 after 50 cycles.

Description of drawings

Accompanying drawing 1 is the SEM image of the positive electrode material of the waste power lithium battery used in the present invention.

2 is an XRD pattern of the regenerated NCM111 ternary cathode material prepared in Example 1 of the present invention.

FIG. 3 is a comparison diagram of the cycle performance between the regenerated NCM111 prepared in Example 1 of the present invention and the waste positive electrode active material.

4 is a scanning electron microscope image of the NCM523 ternary cathode material prepared in Experimental Example 2 of the present invention.

FIG. 5 is a schematic flowchart of the industrial application of the present invention.

It can be seen from Figure 1 that the particle size of the waste positive active material is different, and the agglomeration is serious.

It can be seen from Figure 2 that the XRD peak of the regenerated NCM111 positive electrode material is sharper, the peak splitting degree is obvious, and the layered arrangement is orderly.

It can be seen from Figure 3 that the cycle performance of the battery is greatly improved compared with the waste cathode active material. It can be seen from Fig. 4 that the obtained material is spherical with uniform distribution and a size of about 100-300 nm.

It can be seen from FIG. 5 that the process flow diagram of the present invention is industrialized.

Detailed ways

The present invention will be described in further detail below in conjunction with specific embodiments, but the present invention is not limited to the following embodiments.

In the following cases, the amount of biomass used is based on dry weight, and the particle size is pulverized to 200 mesh to 300 mesh.

Example 1:

①Pretreatment: put the waste power lithium battery (the positive active material of which is LiNi _1/3 Co _1/3 Mn _1/3 O ₂ ) into 5mol/L brine for 30min discharge treatment, and put the discharged battery at 80℃ Drying, dismantling and separating the positive electrode sheet, dissolving the positive electrode sheet in N-methylpyrrolidone, removing the current collector in the positive electrode sheet, filtering, washing and drying to obtain the waste positive electrode active material;

②Reduction roasting: Weigh 10g of waste cathode active material and an appropriate amount of corn stalks, the doping content of corn stalks is 30%, ball mill for 2 hours to mix evenly, put the mixture in a tube furnace, and sinter at 800 °C for 5 hours in an Ar atmosphere to obtain reduction roasting slag;

3. Water leaching: take the above-mentioned reduced roasting slag, add it to 350 mL of water at a liquid-solid ratio (mL:g) of 30:1, and filter with magnetic stirring for 1 h at 20° C. to obtain water leaching solution and water leaching slag;

④ Lithium carbide precipitation: add excess Na ₂ CO ₃ (excess coefficient 1.60) to the above water immersion solution, stir at 80° C. for 3 hours and filter to obtain Li ₂ CO ₃ ;

5. Removal of impurities: the above acid leaching solution is placed in a constant temperature water bath, heated to 60°C, and 2mol/L NaOH solution is slowly added to adjust the pH to 5-6 and the reaction is continued for 2h, and the filtered solution is added with coconut shells with an iodine value of 1200 Activated carbon 2g/L to remove oil, filter and wash to obtain purified liquid;

⑥ Rapid co-precipitation + hydrothermal: adding NiSO ₄ ·6H ₂ O, CoSO ₄ ·7H ₂ O and MnSO ₄ ·H ₂ O to the purification solution obtained in the previous step to adjust Ni:Co:Mn=1:1:1, Quickly add 1 mol/L NaOH and 2 mol/L ammonia water to adjust pH=11.5, react for 30 min and place in a hydrothermal reactor for 4 h at 180°C for hydrothermal reaction, filter and wash to obtain a ternary precursor;

⑦ The above-mentioned ternary precursor was mixed with LiCO ₃ for 40 minutes and then placed in a tube furnace, and calcined at 850° C. for 4 hours in an oxygen atmosphere to obtain a regenerated NCM111 ternary cathode material. In this embodiment, the recovery rate of Ni is 97%, the recovery rate of Co is 96%, the recovery rate of Mn is 96%, and the recovery rate of Li is 98%.

The particle size of the obtained NCM111 ternary cathode material is 300 nm; the specific capacity of the initial charge and discharge is 158 mAh/g, and after 50 cycles, the specific capacity is 136 mAh/g.

Example 2:

①Pretreatment: put the waste power lithium battery (its positive active material is LiNi _0.5 Co _0.2 Mn _0.3 O ₂ ) into 5mol/L brine for 30min discharge treatment, dry the discharged battery at 80 ℃, disassemble and separate The positive electrode sheet is taken out, the positive electrode sheet is dissolved in N-methylpyrrolidone, the current collector in the positive electrode sheet is removed, and the waste positive electrode active material is obtained by filtration, washing and drying;

②Reduction roasting: Weigh 10g of waste positive active material and an appropriate amount of rice husks, the doping content of the rice husks is 20%, ball mill for 2 hours to mix uniformly, put the mixture in a tube furnace, and sinter at 750 °C for 6 hours under _N2 atmosphere. reduction roasting slag;

3. Water leaching: take the above-mentioned reduction roasting slag, add it to 500 mL of water at a liquid-solid ratio (mL:g) of 50:1, and filter with magnetic stirring for 1 h at 20° C. to obtain water leaching solution and water leaching slag;

④ Lithium hydroxide preparation: add lime (excess coefficient 1.08) to the above water leaching solution, stir at 80°C for 4h and filter the obtained filtrate by vacuum evaporation and crystallization to prepare LiOH;

⑤ Impurity removal: place the above acid leaching solution in a constant temperature water bath, heat to 60°C, slowly add 4mol/L NaOH solution to adjust the pH to 5-6 and continue the reaction for 2h, add coconut shells with an iodine value of 1200 to the filtered solution Activated carbon 3g/L to remove oil, filter and wash to obtain purified liquid;

⑥ Rapid co-precipitation + hydrothermal: adding NiSO ₄ ·6H ₂ O, CoSO ₄ ·7H ₂ O and MnSO ₄ ·H ₂ O to the purification solution obtained in the previous step to adjust Ni:Co:Mn=5:2:3, Quickly add 1 mol/L NaOH and 2 mol/L ammonia water to adjust pH=11.5, react for 20 min and place in a hydrothermal reactor at 200°C for hydrothermal reaction for 4 h, filter and wash to obtain a ternary precursor;

⑦ The ternary precursor in the previous step was mixed and ground with LiCO ₃ for 40 min, then placed in a tube furnace, and calcined at 800 °C for 6 h in an oxygen atmosphere to obtain a regenerated NCM523 ternary cathode material.

In this embodiment, the recovery rate of Ni is 98%, the recovery rate of Co is 96%, the recovery rate of Mn is 98%, and the recovery rate of Li is 99%.

The particle size of the obtained NCM523 ternary cathode material is 280 nm; the specific capacity of the initial charge and discharge is 168 mAh/g, and after 50 cycles, the specific capacity is 152 mAh/g.

Example 3:

①Pretreatment: Put the waste power lithium battery (its positive active material is LiNi _0.6 Co _0.2 Mn _0.2 O ₂ ) into 5mol/L brine for 30min discharge treatment, dry the discharged battery at 80℃, disassemble and separate The positive electrode sheet is taken out, the positive electrode sheet is dissolved in N-methylpyrrolidone, the current collector in the positive electrode sheet is removed, and the waste positive electrode active material is obtained by filtration, washing and drying;

②Reduction roasting: Weigh 10g of waste cathode active material and an appropriate amount of straw, the doping content of straw is 25%, ball mill for 2 hours to mix evenly, place the mixture in a tube furnace, and sinter at 750 °C for 5 hours in an Ar atmosphere to obtain reduced roasting slag ;

3. Water leaching: take the above-mentioned reduction roasting slag, add it to 550 mL of water at a liquid-solid ratio (mL:g) of 60:1, and filter with magnetic stirring for 1 h at 30°C to obtain water leaching solution and water leaching slag;

④ Lithium hydroxide preparation: LiOH is prepared by adding lime (excess coefficient 1.05) to the above-mentioned water leaching solution, and stirring the filtrate obtained by filtration at 80° C. for 4h under reduced pressure evaporation and crystallization;

⑤ Impurity removal: place the above acid leaching solution in a constant temperature water bath, heat to 60°C, slowly add 3mol/L NaOH solution to adjust the pH to 5-6 and continue the reaction for 2h, add coconut shells with an iodine value of 1200 to the filtered solution Activated carbon 3g/L to remove oil, filter and wash to obtain purified liquid;

⑥ Rapid co-precipitation + hydrothermal: adding NiSO ₄ ·6H ₂ O, CoSO ₄ ·7H ₂ O and MnSO ₄ ·H ₂ O to the purification solution obtained in the previous step to adjust Ni:Co:Mn=6:2:2, Quickly add 2 mol/L NaOH and 4 mol/L ammonia water to adjust pH=11.0, place in a hydrothermal reactor for 10 min and then place in a hydrothermal reaction kettle for 6 h at 200°C, filter and wash to obtain a ternary precursor;

⑦ The ternary precursor in the previous step was mixed and ground with LiOH·H ₂ O for 40 minutes, then placed in a tube furnace, and calcined at 800 °C for 6 hours in an oxygen atmosphere to obtain a regenerated NCM622 ternary cathode material. In this embodiment, the recovery rate of Ni is 98%, the recovery rate of Co is 97%, the recovery rate of Mn is 97%, and the recovery rate of Li is 99%.

The particle size of the obtained NCM622 ternary cathode material is 200 nm; the specific capacity of the initial charge and discharge is 172 mAh/g, and after 50 cycles, the specific capacity is 163 mAh/g.

Example 4:

①Pretreatment: Put the waste power lithium battery (its positive active material is LiNi _0.8 Co _0.1 Mn _0.1 O ₂ ) into 5mol/L brine for 30min discharge treatment, dry the discharged battery at 80℃, disassemble and separate The positive electrode sheet is taken out, the positive electrode sheet is dissolved in N-methylpyrrolidone, the current collector in the positive electrode sheet is removed, and the waste positive electrode active material is obtained by filtration, washing and drying;

②Reduction roasting: Weigh 10g of waste positive active material and an appropriate amount of rapeseed cake, the amount of rapeseed cake waste is 30%, ball-milled for 2 hours to mix evenly, the mixed material is placed in a tube furnace, and sintered at 800 ℃ in an Ar atmosphere 6h to obtain reduced roasting slag;

3. Water leaching: take the above-mentioned reduction roasting slag, add it to 650 mL of water at a liquid-solid ratio (mL:g) of 80:1, and filter with magnetic stirring for 1 h at 30°C to obtain water leaching solution and water leaching slag;

④ Lithium carbide precipitation: add excess Na ₂ CO ₃ (excess coefficient 2.10) to the above water immersion solution, stir at 80° C. for 3 hours and filter to obtain Li ₂ CO ₃ ;

⑤ Impurity removal: place the above acid leaching solution in a constant temperature water bath, heat to 60°C, slowly add 3mol/L NaOH solution to adjust the pH to 5-6 and continue the reaction for 2h, add coconut shells with an iodine value of 1200 to the filtered solution Activated carbon 2g/L to remove oil, filter and wash to obtain purified liquid;

⑥ Rapid co-precipitation + hydrothermal: adding NiSO ₄ ·6H ₂ O, CoSO ₄ ·7H ₂ O and MnSO ₄ ·H ₂ O to the purification solution obtained in the previous step to adjust Ni:Co:Mn=8:1:1, Quickly add 2 mol/L NaOH and 4 mol/L ammonia water to adjust pH=11.0, place in a hydrothermal reactor for 20 min and then place in a hydrothermal reaction kettle for 6 h at 200 °C, filter and wash to obtain a ternary precursor;

⑦ The ternary precursor in the previous step was mixed and ground with LiOH·H ₂ O for 40 minutes, then placed in a tube furnace, and calcined at 750°C for 8 hours in an oxygen atmosphere to obtain a regenerated NCM811 ternary cathode material. In this embodiment, the recovery rate of Ni is 99%, the recovery rate of Co is 98%, the recovery rate of Mn is 98%, and the recovery rate of Li is 99%.

The particle size of the obtained NCM811 ternary cathode material is 220 nm; the specific capacity of the initial charge and discharge is 190 mAh/g, and after 50 cycles, the specific capacity is 177 mAh/g.

Comparative Example 1

Other conditions and steps are consistent with Example 1, the difference is: the doping amount of corn stalk is 5% during reduction roasting, the low doping amount results in incomplete reduction, lithium is not completely released from the layered lattice, and lithium is leached out. rate is only 32%.

Comparative Example 2

Other conditions and steps are all consistent with embodiment 1, the difference is: the roasting temperature is 600 DEG C during the reduction roasting, and the result finds that the corn stover reducing ability is insufficient during low temperature, and the reduction is incomplete, and the ternary layered structure is not destroyed, causing lithium. The leaching rate is only 47%.

Comparative Example 3

Other conditions and steps are all consistent with embodiment 1, the difference is: the liquid-solid ratio is 5:1 during the water immersion, and the result finds that the low liquid-solid ratio is unfavorable for the leaching of lithium, because the lithium carbonate is a slightly soluble matter, the water immersion While the temperature cannot be too high, the liquid-solid ratio becomes the biggest limiting factor, and the lithium leaching rate is only 49%.

Comparative Example 4

Other conditions and steps are all consistent with embodiment 1, and the difference is: step ⑥, only adopts rapid co-precipitation, and concrete operation is: in the purification solution obtained in the previous step, add NiSO ₄ .6H ₂ O, CoSO ₄ .7H ₂ O and MnSO ₄ ·H ₂ O adjusted Ni:Co:Mn=1:1:1, quickly added 2mol/L NaOH and 4mol/L ammonia water to adjust pH=11.0, reacted for 30min, filtered and washed to obtain a ternary precursor;

In this comparative example, the recovery rate of Ni is 95%, the recovery rate of Co is 94%, the recovery rate of Mn is 94%, and the recovery rate of Li is 96%.

The particle size of the obtained NCM111 ternary cathode material is 10 μm; the specific capacity of the initial charge and discharge is 148 mAh/g, and after 50 cycles, the specific capacity is 126 mAh/g.

Comparative Example 5

Other conditions and steps are all consistent with embodiment 1, and the difference is: step 2., adopt lignite to be a reducing agent, and the results find that the recovery rate of Li is 81%, and the particle diameter of the gained NCM111 ternary positive electrode material is 500nm; After discharge, its specific capacity is 142mAh/g, and after 50 cycles, its specific capacity is 121mAh/g.

Comparative Example 6

Other conditions and steps are all consistent with embodiment 1, and the difference is: step ⑥, adopts conventional co-precipitation+hydrothermal method, and concrete operation is: in the purification solution of previous step gained, add NiSO ₄ 6H ₂ O, CoSO ₄ ·7H ₂ O and MnSO ₄ ·H ₂ O to adjust Ni:Co:Mn=1:1:1, under the protection of argon atmosphere, slowly add 2mol/L NaOH and 4mol/L ammonia water to adjust pH=11.0, the addition time is 2h , continue the aging reaction for 24h after the feeding is completed; continue to put the above solution in the hydrothermal reaction kettle for 4h hydrothermal reaction at 180°C, filter and wash to obtain the ternary precursor;

In this comparative example, the particle size of the NCM111 ternary positive electrode material is 8 μm; the specific capacity is 147 mAh/g after initial charge and discharge, and the specific capacity is 128 mAh/g after 50 cycles. Compared with the rapid co-precipitation + hydrothermal method, the regenerative ternary cathode material prepared by the conventional co-precipitation + hydrothermal method has large particle size and poor performance, and the conventional co-precipitation + hydrothermal method takes too long to prepare and requires inert gas protection. , the rapid co-precipitation + hydrothermal method overcomes the above shortcomings and has more advantages in comparison.

Claims (10)

1. A method for recycling and regenerating a waste lithium battery anode material under the assistance of biomass waste is characterized by comprising the following steps: the method comprises the following steps:

the first step is as follows: reduction roasting

Carrying out reduction roasting on the biomass and the waste anode powder in a protective atmosphere at the temperature of 700-800 ℃ to obtain a reduction roasting material; wherein the adding amount of the biomass is 10-30% of the mass of the waste anode powder;

second, water immersion

Soaking the reducing material obtained in the first step in water to obtain a water leaching solution and water leaching slag;

third step, preparation of lithium source

Precipitating and recycling the water extract obtained in the second step as a raw material to obtain a lithium source;

the fourth step, acid leaching

Acid leaching the water leaching residue obtained in the second step under the action of an acid system to obtain acid leaching solution;

fifth step, ternary precursor preparation

Removing impurities from the pickle liquor obtained in the fourth step to obtain a purified liquor, adjusting the proportion of nickel, cobalt and manganese in the purified liquor, performing rapid coprecipitation in advance, and performing hydrothermal reaction to prepare a ternary precursor;

sixth step, preparation of ternary cathode material

And grinding the ternary precursor obtained in the fifth step and the lithium source obtained in the third step uniformly, roasting, and regenerating to obtain the ternary cathode material.

2. The method for recycling and regenerating the positive electrode material of the waste lithium battery under the assistance of the biomass waste material as claimed in claim 1, wherein the method comprises the following steps: the waste positive electrode powder is at least one of lithium cobaltate, lithium manganate, lithium nickel manganese oxide and lithium nickel cobalt manganese oxide.

3. The method for recycling and regenerating the positive electrode material of the waste lithium battery under the assistance of the biomass waste material as claimed in claim 1, wherein the method comprises the following steps: the biomass is an organic carbon source, preferably at least one of corn stalks, rapeseed cakes, chaffs, straws, sawdust and sorghum vinasse;

the particle size of the biomass is preferably 200 to 300 meshes.

4. The method for recycling and regenerating the positive electrode material of the waste lithium battery under the assistance of the biomass waste material as claimed in claim 1, wherein the method comprises the following steps: the temperature of the reduction roasting is 750-800 ℃;

the time of the reduction roasting is 1-8 h.

5. The method for recycling and regenerating the waste lithium battery anode material assisted by the biomass waste as claimed in claim 1, wherein the liquid-solid ratio (m L: g) of the deionized water to the reduction roasting material is 20:1-100:1 in the water leaching process.

6. The method for recycling and regenerating the positive electrode material of the waste lithium battery under the assistance of the biomass waste material as claimed in claim 1, wherein the method comprises the following steps: in the third step, the prepared lithium source is lithium hydroxide or lithium carbonate;

wherein the step of preparing lithium hydroxide comprises: adding lime into the water extract obtained in the second step to prepare lithium hydroxide solid by a lithium carbonate causticization method, or

The lithium carbonate preparation steps are as follows: adding a carbonizing agent into the water extract, and preparing the lithium carbonate at the temperature of between 60 and 90 ℃ for 1 to 5 hours, wherein the carbonizing agent is sodium carbonate or sodium bicarbonate, and the excessive coefficient of the carbonizing agent is between 1.05 and 3.0.

7. The method for recycling and regenerating the waste lithium battery anode material assisted by the biomass waste as claimed in claim 1, wherein the acid adopted in the acid leaching process is sulfuric acid, the concentration of the sulfuric acid is 1.5-5 mol/L, the acid leaching temperature is 15-95 ℃, and the liquid-solid ratio is 3:1-5: 1.

8. The method for recycling and regenerating the anode materials of the waste lithium batteries assisted by the biomass waste as claimed in claim 1, wherein the impurity removal step comprises the steps of firstly adjusting the pH value of the pickle liquor obtained in the fourth step to 5-6 by using a 2-5 mol/L NaOH solution, removing aluminum and iron impurities through hydrolysis, then adding 2-3 g/L of activated carbon with an iodine value higher than 1200 to remove oil, and obtaining a purified liquor after filtering.

9. The method for recycling and regenerating the waste lithium battery anode material assisted by the biomass waste as claimed in claim 1, wherein the rapid co-precipitation process comprises the steps of taking ammonia water with a concentration of 2-6 mol/L and NaOH solution with a concentration of 1-3 mol/L as a complexing agent and a precipitating agent, adjusting the pH of the solution to 11-12, and performing rapid co-precipitation reaction at 40-70 ℃ for 10-30 min;

preferably, the system of the rapid coprecipitation reaction is subjected to a hydrothermal reaction at the temperature of 160-220 ℃, and then the ternary precursor is obtained by filtering, washing and drying.

10. The method for recycling and regenerating the waste lithium battery anode material assisted by the biomass waste as claimed in claim 1, wherein in the sixth step, the ternary precursor obtained in the fifth step and the lithium source prepared in the third step are mixed, ground uniformly and then roasted in an oxygen atmosphere to obtain the regenerated ternary anode material L iNi_xCo_yMn_zO₂(ii) a The roasting temperature is 600-1000 ℃, and the roasting time is 4-12 h;

preferably, the regenerated ternary cathode material is L iNi_1/3Co_1/3Mn_1/3O₂、LiNi_0.5Co_0.2Mn_0.3O₂、LiNi_0.6Co_0.2Mn_0.2O₂Or L iNi_0.8Co_0.1Mn_0.1O₂One of them, the size is 100-300 nm.

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