Method for directional reduction of valuable metals from hydrogen produced by catalytic pyrolysis of waste and old ternary lithium battery diaphragm

Abstract

The application discloses a method for directional reduction of valuable metals by hydrogen production through catalytic pyrolysis of waste ternary lithium battery separators, and belongs to the field of waste lithium battery recycling industry. After discharge, disassembly, crushing and screening, the waste ternary lithium battery is obtained as a shell, positive and negative electrode materials, a current collector, a separator and an electrolyte. The separator is used as a raw material to release volatile matter in a pyrolysis unit in an inert atmosphere. Less than 10% of the positive electrode material is taken as a catalyst, and the volatile matter is introduced into a catalytic reforming unit to obtain hydrogen-rich gas. The hydrogen-rich gas is introduced into a medium-temperature reduction unit to realize the reduction of high-valence metals such as nickel, cobalt and manganese in more than 80% of the positive electrode material. The solid particles collected from the catalytic reforming unit and the medium-temperature reduction unit are used as reduction black powder, and the reduction black powder is added to an acid solution without an additional reducing agent for leaching and recycling of valuable metals. Therefore, the method can effectively utilize the endogenous separator and positive electrode material of the lithium battery, obtain hydrogen-rich gas with high yield, and the catalyst has strong stability, avoiding the problems of easy sintering and poor reusability of conventional catalysts. The recovery rate of valuable metals is more than 90%, and the problems of high cost and serious secondary pollution caused by the introduction of an additional reducing agent are solved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of waste lithium battery recycling industry, and particularly relates to a method for preparing hydrogen and reducing valuable metals by catalytic pyrolysis of a separator of a waste ternary lithium battery. BACKGROUND

[0002] With the increasing demand for mobile energy sources of electric vehicles and electronic products, ternary lithium batteries are increasingly used due to their wide working temperature range, high conversion efficiency, large energy density, long cycle life and other characteristics. However, when the performance of lithium ion batteries declines, a large number of retired lithium ion batteries will inevitably be produced. It is reported that by 2030, the global consumption of lithium ion batteries will exceed 11 million tons. On the one hand, waste lithium ion batteries contain a large amount of valuable metals (Li, Ni, Co, Mn, etc.) and other recyclable materials, which have high potential value. On the other hand, if not properly treated, it will cause serious environmental problems such as heavy metal pollution and plastic garbage. Therefore, the recycling of waste lithium ion batteries not only meets the economic requirements, but also meets the environmental requirements.

[0003] Hydrometallurgical method is widely used for recovering valuable metals from waste lithium ion batteries due to its high efficiency and low energy consumption, and the leaching process is usually carried out in organic or inorganic acid solution. However, due to the presence of transition metals in high valence state in lithium batteries, it is difficult to dissolve and the leaching efficiency is low, so a reducing agent must be used to reduce the high valence transition metal to low valence state for dissolution and leaching. Generally, inorganic (such as H2O2, Na2SO3) or organic (such as glucose, sucrose, cellulose or citric acid) reducing agents are used to reduce high valence metals to improve leaching efficiency, but these reducing agents are expensive and can cause secondary pollution.

[0004] In addition, the separator produced during the disassembly process of waste lithium batteries will cause plastic pollution, and the existing lithium battery disassembly and sorting process does not effectively utilize it. Therefore, by using the pyrolysis of the separator of the waste ternary lithium ion battery, the catalytic reforming of the pyrolysis volatile is used to produce hydrogen-rich reducing gas for directional reduction of transition metals, which can realize the conversion of high valence nickel, cobalt and manganese to low valence state, and the effective utilization of the endogenous separator also avoids the consumption of external carbon source. The conversion of transition metal valence helps to improve the leaching efficiency and increase the recovery rate of the positive electrode material. Therefore, based on the full utilization of the catalytic performance of the metal in the lithium battery, the present application realizes the hydrogen production by pyrolysis of the endogenous separator of the lithium battery, and then uses the hydrogen-rich gas to reduce more positive electrode materials, which not only promotes the full utilization of the separator of the waste lithium battery and avoids plastic pollution, but also realizes the reduction and leaching of the positive electrode material. SUMMARY

[0005] In view of the defects in the existing waste lithium battery recycling technologies, the present application aims to provide a method for preparing hydrogen from waste ternary lithium battery separator membrane catalytic pyrolysis and directional reduction of valuable metals, which aims to make full use of the catalytic performance of the waste ternary lithium battery positive electrode material and the catalytic reforming of the separator membrane to generate hydrogen-rich reducing gas, and solve the plastic pollution caused by the lithium battery separator membrane and the consumption of reducing agent required for high-valence transition metals. Therefore, the whole recycling process is an efficient and economic and environmentally friendly route, and avoids the consumption of expensive reducing agents, and the waste resources are fully utilized, and the like.

[0006] To achieve the above purpose, the present application adopts the following technical solutions:

[0007] A method for preparing hydrogen from waste ternary lithium battery separator membrane catalytic pyrolysis and directional reduction of valuable metals, comprising a discharging unit, a disassembling, crushing and screening unit, a pyrolysis unit, a catalytic reforming unit, a medium-temperature reduction unit and a leaching unit, wherein the pyrolysis unit, the catalytic reforming unit and the medium-temperature reduction unit are carried out in a three-stage furnace, the separator membrane is pyrolyzed in a first-stage furnace, the positive electrode material is used as a catalyst for pyrolysis and volatilization of steam catalytic reforming in a second-stage furnace, and the positive electrode material is reduced in a hydrogen-rich gas in a third-stage furnace. Specifically, the following steps are included:

[0008] 1) After the waste ternary lithium battery is discharged, disassembled, crushed and screened, a shell, positive and negative electrode materials, a current collector, a separator membrane and an electrolyte are obtained;

[0009] 2) The separator membrane is used as a raw material and is reacted in an inert atmosphere in the pyrolysis unit to release volatiles;

[0010] 3) Take less than 10% of the positive electrode material as a catalyst, pass the volatiles into the catalytic reforming unit to obtain a hydrogen-rich gas;

[0011] 4) Pass the hydrogen-rich gas into the medium-temperature reduction unit to realize the reduction of more than 80% of nickel, cobalt and manganese and the like high-valence metals in the positive electrode material;

[0012] 5) Collect the solid particles from the catalytic reforming unit and the medium-temperature reduction unit as reduced black powder, and add the reduced black powder to an acid solution without adding a reducing agent to leach and recover valuable metals.

[0013] A further improvement of the method of the present invention is that, in the steps of discharging, dismantling, crushing and screening the waste ternary lithium battery to obtain the shell, positive and negative electrode materials, current collector, separator and electrolyte, the waste lithium battery is discharged by soaking in a 5 wt.% NaCl solution for 48 hours. After the waste lithium battery is discharged and air-dried, it is manually dismantled to obtain each component. The selected pure positive and negative electrode sheets are crushed separately using a universal pulverizer, with each crushing time being 5 seconds. After the positive and negative electrode waste is crushed, it is screened through a 200-mesh sieve to remove the current collector and obtain the positive and negative electrode materials.

[0014] A further improvement of the method of the present invention is that the pyrolysis unit, the catalytic reforming unit and the intermediate temperature reduction unit all use a protective gas, which is one or more of nitrogen, helium, argon and xenon, and the flow rate of the protective gas is 50-100 mL / min.

[0015] A further improvement of the method of the present invention is that, in the step of reacting and releasing volatiles in an inert atmosphere pyrolysis unit using the diaphragm as raw material, the diaphragm pyrolysis temperature is 500-600℃.

[0016] A further improvement of the method of the present invention is that, in the step of taking less than 10% of the positive electrode material as a catalyst and passing the volatiles into the catalytic reforming unit to react and obtain hydrogen-rich gas, the mass ratio of catalyst to membrane is 0.25~2:1, the water vapor flow rate is 0~8 mL / h, the catalytic reforming temperature is 600-800℃, and the reaction is maintained at a constant temperature for 1h to obtain hydrogen-rich reduced gas.

[0017] A further improvement of the method of the present invention is that, in the step of introducing hydrogen-rich gas into the medium-temperature reduction unit to reduce more than 80% of the high-valence metals such as nickel, cobalt and manganese in the cathode material, the reduction temperature is 500-800℃, and the mass ratio of cathode material to separator is 1~10:1.

[0018] A further improvement of the method of the present invention is that, in the step of using the solid particles collected from the catalytic reforming unit and the intermediate temperature reduction unit as reduced black powder, and adding the reduced black powder to an acid solution without external reducing agent to leach and recover valuable metals, the reduced black powder is leached with sulfuric acid solution at a concentration of 4 mol / L, a leaching time of 30 min, a water bath heating temperature of 80°C, a stirring speed of 150 r / min, and the reduced black powder and sulfuric acid solution are mixed at a mixing ratio of 0.1 g / L.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] 1) The method for directional reduction of valuable metals by catalytic pyrolysis of waste ternary lithium battery separator for hydrogen production provided in the application uses positive electrode material as catalyst and separator as raw material, and obtains hydrogen-rich gas through catalytic reforming of volatile water vapor generated by separator pyrolysis, with the highest gas yield of 74.25 mmol / g and the highest hydrogen yield of 40.29 mmol / g;

[0021] 2) The method for directional reduction of valuable metals by catalytic pyrolysis of waste ternary lithium battery separator for hydrogen production provided in the application uses positive electrode material (LiNi x Co y Mn 1-x-y O2) as catalyst, which mainly generates nickel-cobalt alloy and manganese oxide after catalytic reforming reaction. Since the alloy catalyst has strong stability, it avoids the problems of easy sintering and poor reusability of conventional catalysts, and reduces the cost of catalyst use;

[0022] 3) The method for directional reduction of valuable metals by catalytic pyrolysis of waste ternary lithium battery separator for hydrogen production provided in the application uses hydrogen-rich gas produced by catalytic reforming of volatile matter generated by separator pyrolysis to reduce the transition metal of positive electrode material, without introducing external reducing agent and realizing the reduction of transition metal in positive electrode material. After acid leaching, the recovery rates of valuable metals Li, Ni, Co and Mn are 95.79%, 98.81%, 98.41% and 90.31% respectively, which promotes the recycling of valuable metals in ternary lithium batteries and solves the problems of high cost and serious secondary pollution caused by the introduction of external reducing agent. BRIEF DESCRIPTION OF DRAWINGS

[0023] In order to more clearly illustrate the specific embodiments of the application, the following will briefly introduce the drawings needed to be used in the description of specific embodiments or prior art:

[0024] Figure 1 is a flow chart of the method of the application;

[0025] Figure 2 is an SEM image of the reduction of positive electrode material by hydrogen-rich gas at different reduction temperatures;

[0026] Figure 3 is an XRD spectrum of positive electrode material reduced by hydrogen-rich gas at different reduction temperatures;

[0027] Figure 4 is an SEM image of hydrogen-rich gas at different ratios of positive electrode material to separator;

[0028] Figure 5 is an XRD spectrum of hydrogen-rich gas at different ratios of positive electrode material to separator.

[0029] DETAILED DESCRIPTION

[0030] The application will be further described in detail below in conjunction with the accompanying drawings and examples. The following examples are only descriptive and not limiting, and the protection scope of the application cannot be limited by them. The materials, methods, equipment and devices herein are understood to be commercially available unless otherwise specified.

[0031] A method for directional reduction of valuable metals by catalytic pyrolysis of waste ternary lithium battery separators for hydrogen production, comprising the following steps:

[0032] 1) After discharging, disassembling, crushing and screening, the waste ternary lithium battery is obtained, including the shell, the positive and negative electrode materials, the current collector, the separator and the electrolyte;

[0033] 2) Among them, the separator is the raw material, which is reacted in the pyrolysis unit in an inert atmosphere to release volatile matter;

[0034] 3) Take less than 10% of the positive electrode material as a catalyst, and pass the volatile matter into the catalytic reforming unit to obtain hydrogen-rich gas;

[0035] 4) Pass the hydrogen-rich gas into the medium-temperature reduction unit to realize the reduction of high-valence metals such as nickel, cobalt and manganese in more than 80% of the positive electrode material;

[0036] 5) Collect the solid particles from the catalytic reforming unit and the medium-temperature reduction unit as reduced black powder, and add the reduced black powder to the acid solution without adding a reducing agent for leaching and recycling valuable metals.

[0037] In the following examples, the catalytic pyrolysis and directional reduction of valuable metals of the waste ternary lithium battery separator are carried out in three-stage furnaces. The pyrolysis of the separator is carried out in the first-stage furnace, the pyrolysis of the volatile matter and steam catalytic reforming of the positive electrode material as a catalyst are carried out in the second-stage furnace, and the medium-temperature reduction of the positive electrode material by hydrogen-rich gas is carried out in the third-stage furnace,

[0038] Preferably, in step 2), the pyrolysis temperature of the separator is 500-600°C,

[0039] Preferably, in step 3), the steam catalytic reforming of the pyrolysis volatile matter, the mass ratio of the catalyst to the separator is 0.25-2:1, the steam flow rate is 0-8 mL, the catalytic reforming temperature is 600-800°C, and the hydrogen-rich reduction gas is obtained by keeping the temperature constant for 1h,

[0040] Preferably, in step 4), the hydrogen-rich reduction gas reduces high-valence metals such as nickel, cobalt and manganese in the positive electrode material, the reduction temperature is 500-800°C, and the mass ratio of the positive electrode material to the separator is 1-10:1,

[0041] Preferably, in step 2) and step 3), the protective gas used in the catalytic pyrolysis and reduction stages of the waste ternary lithium battery is one or more of nitrogen, helium, argon and xenon, and the flow rate of the protective gas is 50-100 mL / min. Embodiment

[0042] A method for directional reduction of valuable metals from hydrogen produced by pyrolysis of a waste lithium battery separator according to an embodiment of the present application, as shown in FIG. 1, comprises the following steps:

[0043] 1) After the waste ternary lithium battery is discharged, disassembled, broken and sieved, a shell, a positive and negative electrode material, a current collector, a separator and an electrolyte are obtained;

[0044] 2) The separator as a raw material is reacted in a pyrolysis unit in an inert atmosphere to release volatile matter, and the pyrolysis temperature is 500℃;

[0045] 3) The volatile matter is introduced into a catalytic reforming unit containing the positive electrode material, and the catalytic pyrolysis reaction of the separator is carried out at a catalyst to separator ratio of 2:1, a reforming temperature of 800℃, a water vapor flow rate of 4 mL / h, and a carrier gas N2 flow rate of 100 mL / min. The volatile matter produced by the pyrolysis of the separator enters the catalytic reforming area where the positive electrode material is located to react completely to obtain a reduction gas-rich gas. The collected gas is analyzed by a gas chromatograph, and the synthesis gas yield is 59.13 mmol / g 隔膜 , wherein the hydrogen yield is 29.75 mmol / g 隔膜 ;

[0046] 4) The hydrogen-rich gas is introduced into a medium-temperature reduction unit to realize the reduction of high-valence metals such as nickel, cobalt and manganese in the positive electrode material by more than 80%, and the reduction temperature is 500℃, and the mass ratio of the positive electrode material to the separator is 2:1. As shown in FIG. 3, the XRD pattern of the reduced positive electrode material, and the nickel, cobalt and manganese are not completely reduced;

[0047] 5) The solid particles collected from the catalytic reforming unit and the medium-temperature reduction unit are used as reduction black powder, and the reduction black powder is added to an acid solution without an external reducing agent for leaching and recovery of valuable metals. The sulfuric acid concentration is 4 mol / L, the leaching time is 30 min, the water bath heating temperature is 80℃, the stirring speed is 150 r / min, the reduction black powder is mixed with the sulfuric acid solution, and the mixing ratio is 0.1 g / L. The recovery rates of valuable metals Li, Ni, Co and Mn are 95.79%, 98.81%, 98.41% and 90.31%, respectively.

[0048] Embodiment 2

[0049] The difference between this embodiment and embodiment 1 is that the positive electrode material is used as a catalyst, the separator is used as a raw material, the ratio of the catalyst to the separator is 0.5:1, the pyrolysis temperature is 500°C, the reforming temperature is 700°C, the water vapor flow rate is 4 mL / h, and the carrier gas N2 flow rate is 100 mL / min. The separator catalytic pyrolysis reaction is carried out, and the volatiles generated by the pyrolysis of the separator enter the catalytic reforming area where the positive electrode material is located to completely react to obtain a rich reducing gas. The collected gas is analyzed by a gas chromatograph, and the synthesis gas yield is 42.36 mmol / g 隔膜 , wherein the hydrogen yield is 23.03 mmol / g 隔膜 .

[0050] Example 3

[0051] The difference between this embodiment and embodiment 1 is that the positive electrode material is used as a catalyst, the separator is used as a raw material, the ratio of the catalyst to the separator is 0.5:1, the pyrolysis temperature is 500°C, the reforming temperature is 600°C, the water vapor flow rate is 4 mL / h, and the carrier gas N2 flow rate is 100 mL / min. The separator catalytic pyrolysis reaction is carried out, and the volatiles generated by the pyrolysis of the separator enter the catalytic reforming area where the positive electrode material is located to completely react to obtain a rich reducing gas. The collected gas is analyzed by a gas chromatograph, and the synthesis gas yield is 10.70 mmol / g 隔膜 , wherein the hydrogen yield is 4.47 mmol / g 隔膜 .

[0052] Example 4

[0053] The difference between this embodiment and embodiment 1 is that the positive electrode material is used as a catalyst, the separator is used as a raw material, the ratio of the catalyst to the separator is 0.5:1, the pyrolysis temperature is 500°C, the reforming temperature is 800°C, the water vapor flow rate is 0 mL / h, and the carrier gas N2 flow rate is 100 mL / min. The separator catalytic pyrolysis reaction is carried out, and the volatiles generated by the pyrolysis of the separator enter the catalytic reforming area where the positive electrode material is located to completely react to obtain a rich reducing gas. The collected gas is analyzed by a gas chromatograph, and the synthesis gas yield is 34.83 mmol / g 隔膜 , wherein the hydrogen yield is 13.80 mmol / g 隔膜 .

[0054] Example 5

[0055] This embodiment differs from Embodiment 1 in that: the positive electrode material is used as the catalyst, the membrane is used as the raw material, and the membrane catalytic pyrolysis reaction is carried out at a catalyst-to-membrane ratio of 0.5:1, a pyrolysis temperature of 500℃, a reforming temperature of 800℃, a steam flow rate of 2 mL / h, and a carrier gas N2 flow rate of 100 mL / min. The volatiles generated by the membrane pyrolysis enter the catalytic reforming region where the positive electrode material is located and react completely to obtain hydrogen-rich reducing gas. The collected gas is analyzed by gas chromatography, and the syngas yield is 57.38 mmol / g. 隔膜 The hydrogen yield was 27.85 mmol / g. 隔膜 .

[0056] Example 6

[0057] This embodiment differs from Embodiment 1 in that: the positive electrode material is used as the catalyst, the membrane is used as the raw material, and the membrane catalytic pyrolysis reaction is carried out at a catalyst-to-membrane ratio of 0.5:1, a pyrolysis temperature of 500℃, a reforming temperature of 800℃, a steam flow rate of 8 mL / h, and a carrier gas N2 flow rate of 100 mL / min. The volatiles generated by the membrane pyrolysis enter the catalytic reforming region where the positive electrode material is located and react completely to obtain hydrogen-rich reducing gas. The collected gas is analyzed by gas chromatography, and the syngas yield is 51.88 mmol / g. 隔膜 The hydrogen yield was 25.63 mmol / g. 隔膜 .

[0058] Example 7

[0059] This embodiment differs from Embodiment 1 in that: the positive electrode material is used as the catalyst, the membrane is used as the raw material, and the membrane catalytic pyrolysis reaction is carried out at a catalyst-to-membrane ratio of 2:1, a pyrolysis temperature of 500℃, a reforming temperature of 800℃, a steam flow rate of 4 mL / h, and a carrier gas N2 flow rate of 100 mL / min. The volatiles generated by the membrane pyrolysis enter the catalytic reforming region where the positive electrode material is located and react completely to obtain hydrogen-rich reducing gas. The collected gas is analyzed by gas chromatography, and the syngas yield is 74.25 mmol / g. 隔膜 The hydrogen yield was 40.29 mmol / g. 隔膜 .

[0060] Example 8

[0061] The difference between this embodiment and embodiment 1 is that the positive electrode material is used as a catalyst, the separator is used as a raw material, the ratio of the catalyst to the separator is 1:1, the pyrolysis temperature is 500°C, the reforming temperature is 800°C, the water vapor flow rate is 4 mL / h, and the carrier gas N2 flow rate is 100 mL / min. The separator catalytic pyrolysis reaction is carried out, the volatiles generated by the separator pyrolysis enter the catalytic reforming area where the positive electrode material is located, and the reaction is completely obtained. The hydrogen-rich reducing gas is obtained. The collected gas is analyzed by a gas chromatograph, and the synthesis gas yield is 57.38 mmol / g 隔膜 , wherein the hydrogen yield is 27.85 mmol / g 隔膜 .

[0062] Example 8

[0063] The difference between this embodiment and embodiment 1 is that the positive electrode material is used as a catalyst, the separator is used as a raw material, the ratio of the catalyst to the separator is 0.25:1, the pyrolysis temperature is 500°C, the reforming temperature is 800°C, the water vapor flow rate is 4 mL / h, and the carrier gas N2 flow rate is 100 mL / min. The separator catalytic pyrolysis reaction is carried out, the volatiles generated by the separator pyrolysis enter the catalytic reforming area where the positive electrode material is located, and the reaction is completely obtained. The hydrogen-rich reducing gas is obtained. The collected gas is analyzed by a gas chromatograph, and the synthesis gas yield is 26.65 mmol / g 隔膜 , wherein the hydrogen yield is 8.73 mmol / g 隔膜 .

[0064] Example 9

[0065] The difference between this embodiment and embodiment 1 is that the positive electrode material is used as a catalyst, the separator is used as a raw material, the ratio of the catalyst to the separator is 0.5:1, the pyrolysis temperature is 500°C, the reforming temperature is 800°C, the water vapor flow rate is 4 mL / h, and the carrier gas N2 flow rate is 100 mL / min. The separator catalytic pyrolysis reaction is carried out, the volatiles generated by the separator pyrolysis enter the catalytic reforming area where the positive electrode material is located, and the reaction is completely obtained. The hydrogen-rich reducing gas is obtained. The catalyst is not regenerated, and 10 cycle stability tests are carried out. The collected gas in each cycle experiment is analyzed by a gas chromatograph, and the synthesis gas yield fluctuation value is 27~54 mmol / g 隔膜 , wherein the hydrogen yield fluctuation value is 21~37 mmol / g 隔膜 .

[0066] Example 10

[0067] The difference between this embodiment and embodiment 1 is that the catalytic pyrolysis reaction of the separator is carried out under the reaction conditions of a catalyst to separator ratio of 0.5:1, a pyrolysis temperature of 500°C, a reforming temperature of 800°C, a water vapor flow rate of 4 mL / h, and a carrier gas N2flow rate of 100 mL / min to obtain a hydrogen-rich reducing gas. The hydrogen-rich reducing gas reduces high-valence metals such as nickel, cobalt, and manganese in the ternary lithium battery to low-valence states, the reduction temperature is 600°C, and the mass ratio of the positive electrode material to the separator is 2:1. FIG. 3 shows the XRD pattern of the reduced positive electrode material, and the lithium nickel cobalt manganese oxide is reduced to a nickel-cobalt alloy and manganese oxide.

[0068] Embodiment 11

[0069] The difference between this embodiment and embodiment 1 is that the catalytic pyrolysis reaction of the separator is carried out under the reaction conditions of a catalyst to separator ratio of 0.5:1, a pyrolysis temperature of 500°C, a reforming temperature of 800°C, a water vapor flow rate of 4 mL / h, and a carrier gas N2flow rate of 100 mL / min to obtain a hydrogen-rich reducing gas. The hydrogen-rich reducing gas reduces high-valence metals such as nickel, cobalt, and manganese in the ternary lithium battery to low-valence states, the reduction temperature is 700°C, and the mass ratio of the positive electrode material to the separator is 2:1. FIG. 3 shows the XRD pattern of the reduced positive electrode material, and the lithium nickel cobalt manganese oxide is reduced to a nickel-cobalt alloy and manganese oxide.

[0070] Embodiment 12

[0071] The difference between this embodiment and embodiment 1 is that the catalytic pyrolysis reaction of the separator is carried out under the reaction conditions of a catalyst to separator ratio of 0.5:1, a pyrolysis temperature of 500°C, a reforming temperature of 800°C, a water vapor flow rate of 4 mL / h, and a carrier gas N2flow rate of 100 mL / min to obtain a hydrogen-rich reducing gas. The hydrogen-rich reducing gas reduces high-valence metals such as nickel, cobalt, and manganese in the ternary lithium battery to low-valence states, the reduction temperature is 800°C, and the mass ratio of the positive electrode material to the separator is 2:1. FIG. 3 shows the XRD pattern of the reduced positive electrode material, and the lithium nickel cobalt manganese oxide is reduced to a nickel-cobalt alloy and manganese oxide.

[0072] Embodiment 13

[0073] The difference between this embodiment and embodiment 1 is that the catalytic pyrolysis reaction of the separator is carried out under the reaction conditions of a catalyst to separator ratio of 0.5:1, a pyrolysis temperature of 500°C, a reforming temperature of 800°C, a water vapor flow rate of 4 mL / h, and a carrier gas N2flow rate of 100 mL / min to obtain a hydrogen-rich reducing gas. The hydrogen-rich reducing gas reduces high-valence metals such as nickel, cobalt, and manganese in the ternary lithium battery to low-valence states, the reduction temperature is 700°C, and the mass ratio of the positive electrode material to the separator is 1:1. FIG. 5 shows the XRD pattern of the reduced positive electrode material, and the lithium nickel cobalt manganese oxide is reduced to a nickel-cobalt alloy and manganese oxide.

[0074] Embodiment 14

[0075] The difference between this embodiment and embodiment 1 is that the catalytic pyrolysis reaction of the separator is carried out under the reaction conditions of a catalyst to separator ratio of 0.5:1, a pyrolysis temperature of 500°C, a reforming temperature of 800°C, a water vapor flow rate of 4 mL / h, and a carrier gas N2 flow rate of 100 mL / min to obtain a hydrogen-rich reducing gas. The hydrogen-rich reducing gas reduces high-valence metals such as nickel, cobalt, and manganese in the ternary lithium battery to low-valence states at a reduction temperature of 700°C and a positive electrode material to separator mass ratio of 4:1. FIG. 5 shows the XRD pattern of the reduced positive electrode material, in which lithium nickel cobalt manganese oxide is partially reduced to a nickel-cobalt alloy and partially reduced to nickel oxide and cobalt oxide.

[0076] Embodiment 15

[0077] The difference between this embodiment and embodiment 1 is that the catalytic pyrolysis reaction of the separator is carried out under the reaction conditions of a catalyst to separator ratio of 0.5:1, a pyrolysis temperature of 500°C, a reforming temperature of 800°C, a water vapor flow rate of 4 mL / h, and a carrier gas N2 flow rate of 100 mL / min to obtain a hydrogen-rich reducing gas. The hydrogen-rich reducing gas reduces high-valence metals such as nickel, cobalt, and manganese in the ternary lithium battery to low-valence states at a reduction temperature of 700°C and a positive electrode material to separator mass ratio of 4:1. FIG. 5 shows the XRD pattern of the reduced positive electrode material, in which lithium nickel cobalt manganese oxide is partially reduced to a nickel-cobalt alloy and partially reduced to nickel oxide and cobalt oxide.

[0078] As can be seen from embodiments 1-8, the catalytic reforming temperature, the water vapor flow rate, and the catalyst to separator mass ratio all affect the hydrogen-rich gas yield of the catalytic reforming reaction. When the reforming temperature increases from 600°C to 800°C, the hydrogen-rich gas yield is significantly improved, and when the temperature increases to 900°C, the sintering of the catalyst causes the gas yield to decrease. Water vapor promotes the water vapor shift reaction and the methane steam reforming reaction, and the hydrogen-rich gas yield is greatly improved. Increasing the catalyst to separator mass ratio promotes the catalytic reforming reaction of the separator, and a higher hydrogen-rich gas yield is obtained per unit mass of the separator. In summary, the hydrogen-rich gas prepared by the separator catalytic pyrolysis technology of the waste ternary lithium battery has a significant effect on both quality and yield.

[0079] As can be seen from embodiments 1 and 10-15, the transition metals in the positive electrode material can be completely reduced by the hydrogen-rich gas at 600°C, and when the positive electrode material to separator ratio is less than 2:1, nickel and cobalt can be completely reduced to a nickel-cobalt alloy, and when the ratio is greater than 4:1, nickel and cobalt are partially reduced to a nickel-cobalt alloy and partially reduced to nickel oxide and cobalt oxide. However, the leaching rates of the valuable metals Li, Ni, Co, and Mn are all greater than 95%. In summary, the hydrogen-rich gas prepared by the separator catalytic pyrolysis technology of the waste ternary lithium battery has a significant effect on both quality and yield, and the reduction of the positive electrode material by the hydrogen-rich gas also has a significant effect.

Claims

1. A method for the directional reduction of valuable metals to produce hydrogen through catalytic pyrolysis of waste ternary lithium battery separators, characterized in that, The system comprises a discharge unit, a dismantling, crushing, and screening unit, a pyrolysis unit, a catalytic reforming unit, a medium-temperature reduction unit, and a leaching unit. The pyrolysis, catalytic reforming, and medium-temperature reduction units are carried out in a three-stage furnace. The first stage furnace performs pyrolysis of the separator; the second stage furnace performs pyrolysis and catalytic reforming of the positive electrode material using volatile water vapor as a catalyst; and the third stage furnace performs medium-temperature reduction of the positive electrode material using hydrogen-rich gas. Specifically, the system includes the following steps: After discharge, dismantling, crushing, and screening, waste ternary lithium batteries yield the casing, positive and negative electrode materials, current collectors, and separators. The process involves reacting the membrane as a raw material in an inert atmosphere pyrolysis unit to release volatiles; using less than 10% of the cathode material as a catalyst, the volatiles are passed into a catalytic reforming unit to react and obtain hydrogen-rich gas; the hydrogen-rich gas is then passed into a medium-temperature reduction unit to reduce more than 80% of the high-valence metals such as nickel, cobalt, and manganese in the cathode material; the solid particles collected from the catalytic reforming unit and the medium-temperature reduction unit are used as reduction black powder, which is then added to an acid solution without an external reducing agent to leach and recover valuable metals.

2. The method for directional reduction of valuable metals to hydrogen through catalytic pyrolysis of waste ternary lithium battery separators according to claim 1, characterized in that, In the process of discharging, dismantling, crushing and screening the waste ternary lithium batteries to obtain the shell, positive and negative electrode materials, current collectors, separators and electrolytes, the waste lithium batteries are discharged by soaking in a 5 wt.% NaCl solution for 48 hours. After the waste lithium batteries are discharged and air-dried, they are manually dismantled to obtain each component. The selected pure positive and negative electrode sheets are crushed separately using a universal crusher, with each crushing time being 5 seconds. After the positive and negative electrode waste is crushed, it is screened through a 200-mesh sieve to remove the current collector and obtain the positive and negative electrode materials.

3. The method for directional reduction of valuable metals to hydrogen through catalytic pyrolysis of waste ternary lithium battery separators according to claim 1, characterized in that, The pyrolysis unit, catalytic reforming unit, and intermediate temperature reduction unit all use a protective gas, which is one or more of nitrogen, helium, argon, and xenon, with a flow rate of 50-100 mL / min.

4. The method for directional reduction of valuable metals to hydrogen through catalytic pyrolysis of waste ternary lithium battery separators according to claim 1, characterized in that, The diaphragm is used as raw material, and in the pyrolysis unit under an inert atmosphere, the reaction release of volatiles occurs at a pyrolysis temperature of 500-600℃.

5. The method for directional reduction of valuable metals to hydrogen through catalytic pyrolysis of waste ternary lithium battery separators according to claim 1, characterized in that, Less than 10% of the positive electrode material is used as the catalyst. The volatiles are passed into the catalytic reforming unit to react and obtain hydrogen-rich gas. The mass ratio of catalyst to membrane is 0.25~2:1, the water vapor flow rate is 0~8mL / h, the catalytic reforming temperature is 600-800℃, and the reaction is maintained at a constant temperature for 1h to obtain hydrogen-rich reducing gas.

6. The method for directional reduction of valuable metals to hydrogen through catalytic pyrolysis of waste ternary lithium battery separators according to claim 1, characterized in that, In the step of introducing hydrogen-rich gas into the medium-temperature reduction unit to reduce more than 80% of the high-valence metals such as nickel, cobalt and manganese in the cathode material, the reduction temperature is 500-800℃, and the mass ratio of cathode material to separator is 1~10:

1.

7. The method for directional reduction of valuable metals to hydrogen through catalytic pyrolysis of waste ternary lithium battery separators according to claim 1, characterized in that, The solid particles collected from the catalytic reforming unit and the intermediate temperature reduction unit are used as reduced black powder. In the step of adding the reduced black powder to an acid solution without external reducing agent to leach and recover valuable metals, sulfuric acid solution is used to leach the reduced black powder to recover valuable metals. The sulfuric acid concentration is 4 mol / L, the leaching time is 30 min, the water bath heating temperature is 80°C, the stirring speed is 150 r / min, and the reduced black powder and sulfuric acid solution are mixed at a mixing ratio of 0.1 g / L.

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