阅读说明：本技术 一种分步焙烧回收废旧锂电池制取阴极活性材料的方法 (Method for preparing cathode active material by recovering waste lithium battery through step-by-step roasting ) 是由 李俊 周志文 朱贤青 彭琴 赖一铭 张亮 付乾 朱恂 廖强 于 2020-12-30 设计创作，主要内容包括：本发明公开了一种分步焙烧回收废旧锂电池制取阴极活性材料的方法,其特征在于：该方法包括如下步骤：A、将废旧锂电池电极活性材料颗粒进行分步焙烧。首先将电极活性材料颗粒在含氧气氛中充分焙烧；待电极材料充分反应后,切换含氧气氛至还原性气氛,使得电极材料焙烧产物被充分还原。焙烧过程中的气相产物直接由尾气处理装置收集处理；B、将分步焙烧后的固相产物进行磁选分离和碳酸浸出提纯；C、将Li-2CO-3浸出液及钴、镍、锰等产物进行过滤、干燥；本发明可实现废旧锂电池的高效回收和资源化利用,可广泛应用于新能源汽车和储能等领域的退役锂离子电池回收。(The invention discloses a method for preparing cathode active materials by recovering waste lithium batteries through step-by-step roasting, which is characterized by comprising the following steps of: the method comprises the following steps: A. and roasting the waste lithium battery electrode active material particles step by step. Firstly, fully roasting electrode active material particles in an oxygen-containing atmosphere; after the electrode material is fully reacted, oxygen is switchedThe atmosphere is changed to a reducing atmosphere so that the electrode material fired product is sufficiently reduced. The gas-phase product in the roasting process is directly collected and treated by a tail gas treatment device; B. carrying out magnetic separation and carbonic acid leaching purification on the solid-phase product subjected to the step-by-step roasting; C. mixing Li 2 CO 3 Filtering and drying the leachate and products of cobalt, nickel, manganese and the like; the invention can realize the high-efficiency recovery and resource utilization of the waste lithium battery, and can be widely applied to the recovery of the retired lithium battery in the fields of new energy vehicles, energy storage and the like.)

1. A method for preparing cathode active materials by recovering waste lithium batteries through step-by-step roasting is characterized by comprising the following steps:

A. screening the crushed waste lithium battery electrode materials, roasting the screened electrode active material particles step by step, roasting the electrode active material particles in an oxygen-containing atmosphere, wherein an oxidation reaction of a carbon material and decomposition of a part of cathode material occur in the roasting process, and the oxidation reaction of carbon realizes rapid decrement of the carbon material in the electrode material and supply of decomposition reaction heat of the cathode material so as to facilitate the reduction of valuable metals; after the electrode material is fully reacted, switching an oxygen-containing atmosphere to a reducing atmosphere, and then roasting the electrode material in the reducing atmosphere to fully reduce a roasted product of the electrode material; the gasification reaction of residual carbon and the metal oxidation-reduction reaction continue to occur in the roasting process of the reducing atmosphere, and the carbon in the electrode material is consumed by the gasification reaction of the carbon, so that the aim of improving the carbon decrement ratio in the electrode material is fulfilled; the metal oxidation-reduction reaction reduces the chemical valence of the valuable metal, so that the valuable metal can be separated later; the gas-phase product in the roasting process is directly collected and treated by a tail gas treatment device;

B. separating and purifying the solid phase product after the step-by-step roasting, which specifically comprises the following steps:

b1, when the cathode material is lithium cobaltate or lithium manganate, adopting carbonic acid leaching method to Li₂CO₃Purifying to simultaneously realize cobalt or manganese metal products and Li₂CO₃Separating;

b2, when the cathode material is a nickel cobalt lithium manganate ternary material, performing magnetic separation and carbonic acid leaching on Li₂CO₃Purifying, and simultaneously mixing the cobalt and nickel simple substances with Li₂CO₃And separating manganese oxide, thereby recovering simple substances of cobalt and nickel;

C. mixing Li₂CO₃Leaching solution and cobalt-nickelFiltering and drying the manganese metal product, specifically:

c1, when the cathode material is lithium cobaltate or lithium manganate, the filtrate is solid Li after being evaporated to dryness₂CO₃Drying the filter residue to obtain a cobalt or manganese product, thereby realizing separation and recovery;

c2, when the cathode material is nickel cobalt lithium manganate ternary material, Li₂CO₃And manganese oxide, filtering and drying, recovering the manganese oxide after filter residues are dried, and recovering solid Li after filtrate is evaporated to dryness₂CO₃。

2. The method for preparing cathode active materials by recycling waste lithium batteries through step roasting according to claim 1, wherein the method further comprises:

D. oxidizing the recovered cobalt product or manganese product, and mixing with Li₂CO₃Mixing and grinding the raw materials according to a certain proportion, and preparing a regenerated lithium cobaltate or lithium manganate cathode active material by adopting a solid-phase sintering method.

3. The method for preparing cathode active materials by stepwise roasting and recycling waste lithium batteries according to claim 1 or 2, characterized in that: in the step A, the gas for roasting in the oxygen-containing atmosphere not only comprises a pure oxygen atmosphere, but also comprises a mixed atmosphere of oxygen and inert gas, or oxidizing atmosphere such as air and the like; the gas for roasting in the reducing atmosphere is a single gas or a mixed gas of the single gases, the single gas is an active gas capable of reacting with carbon to generate a reducing gas, or the single gas is a reducing gas not containing oxygen and the reducing gas is capable of performing an oxidation-reduction reaction with the electrode material under roasting conditions.

Technical Field

The invention relates to waste lithium battery recovery, in particular to a method for preparing a cathode active material by recovering waste lithium batteries through step-by-step roasting.

Background

As a clean energy technology, the lithium ion battery is widely applied to the fields of electric vehicles, energy storage products, digital products and the like. Particularly in the field of electric vehicles, the number of power batteries has increased exponentially in recent years, and generally, the power batteries are subject to replacement when the capacity of the power batteries is reduced to below 80%, and the generation of a large amount of waste lithium ion batteries is accompanied. It is predicted that the total amount of waste lithium ion batteries reaches 1100 ten thousand tons by 2030, and only less than 5% of the waste lithium ion batteries are recycled at present. In addition, the production of a large number of lithium ion batteries also brings related production raw materials to be in short supply, and the waste lithium ion batteries contain abundant valuable metals such as cobalt, nickel, manganese, lithium and the like, so that the unreasonable disposal of the batteries brings serious environmental pollution problems. Therefore, the recovery of the waste lithium batteries is of great significance from the aspects of industrial sustainability development, resource conservation, environmental protection and economic benefit.

Researchers have carried out a lot of researches on the recovery of waste lithium ion batteries, mainly including wet recovery and dry (pyrogenic) recovery. However, in the conventional dry method (high-temperature metallurgy method), the waste battery monomer or module which is not pretreated is directly put into a high-temperature smelting furnace, coke, smelting slag and the like are used as auxiliary materials, and high-temperature smelting is carried out at a temperature (about 1500 ℃) higher than the melting point of valuable metals, so that the valuable metal alloys such as cobalt and nickel are obtained, and the recovery of the valuable metal alloys is realized. The method has the advantages of simple flow, large treatment capacity and convenience for large-scale application, but also has the problems of high energy consumption, pollution of gas emissions, incapability of realizing recovery of valuable metals such as lithium, manganese and the like. The wet recovery is a method for leaching valuable metals in the waste batteries into a solution by adopting media such as acid/alkali/organism and the like, and then realizing valuable metal separation by methods such as precipitation/extraction and the like. The method has high product purity, but has complex process, excessive reagent consumption and secondary pollution.

The reduction roasting method is a new recovery treatment technology of waste lithium ion battery using dry method as main material and wet method as auxiliary material, and is characterized by that firstly, the electrode powder is heat-treated at the temperature (below 1000 deg.C) lower than melting point of valuable metal in electrode active material, and the battery cathode active material (for example LiCoO) is reduced by using carbothermic reduction reaction₂(LCO)，LiMn₂O₄(LMO) and LiNi_XCo_YMn_1-X-YO₂(NCM) and the like) into a metal simple substance or a metal oxide, and then separating the reduction roasting product by acid leaching or a physical method, wherein the whole process has low acid consumption or no acid consumption. The reduction roasting method has the advantages of a dry method and a wet method, can reduce energy consumption and reagent consumption at the same time, and is a treatment method with great application prospect. However, since the cathode material of the lithium ion battery contains not only an active material but also a carbon material and a binder, etc., which serve only a conductive function; and the anode material consists essentially of a carbon material and a binder. The carbon material in these electrode materials only participates in the carbothermic reduction reaction, and the content thereof is often excessive in the recovery process. Excessive carbon residue will seriously affect the separation and purification of valuable metals in the post-treatment, increase the post-treatment difficulty and increase the reagent consumption. In laboratory conditions, in order to solve the problem, the cathode and anode materials are separated manually and then processedThe proportion is adjusted, but the manual operation is not beneficial to mechanized large-scale treatment, and the large-scale application of the reduction roasting method is greatly limited.

Disclosure of Invention

The invention aims to provide a method for preparing a cathode active material by recovering waste lithium batteries through step-by-step roasting.

The technical scheme of the invention is that the method for preparing the cathode active material by roasting and recycling the waste lithium battery step by step is characterized in that: the method comprises the following steps:

A. screening electrode materials of the waste lithium batteries, and roasting the screened electrode active material particles step by step. Firstly, roasting electrode active material particles in an oxygen-containing atmosphere, wherein an oxidation reaction of a carbon material and decomposition of a part of cathode material occur in the roasting process, and the oxidation reaction of carbon realizes rapid decrement of a part of carbon and supply of decomposition reaction heat of the cathode material so as to reduce valuable metals in the following process; after the electrode material is fully reacted, switching the oxygen-containing atmosphere to the reducing atmosphere, and then carrying out reducing atmosphere roasting to ensure that the electrode material roasting product is fully reduced. The gasification reaction of residual carbon and the metal oxidation-reduction reaction continue to occur in the roasting process of the reducing atmosphere, and the gasification reaction of carbon continues to consume carbon in the electrode material, so that the effect of improving the carbon decrement ratio is achieved; the chemical valence of the nonferrous metal is reduced by metal reduction reaction so as to facilitate the separation of the valuable metal; and gas-phase products in the roasting process are directly collected and treated by a tail gas treatment device.

B. Separating and purifying a solid-phase product in the roasting process, which specifically comprises the following steps:

b1, when the cathode material is LCO or LMO, adopting carbonic acid leaching method to Li₂CO₃Purifying to simultaneously realize cobalt or manganese metal products and Li₂CO₃And (5) separating.

B2, when the cathode material is NCM ternary material, adopting magnetic separation and carbonic acid leaching method to Li₂CO₃Purifying, and simultaneously mixing the cobalt and nickel simple substances with Li₂CO₃And separating the oxides of manganese, thereby recovering the elementary substances of cobalt and nickel.

C. Mixing L withi₂CO₃Filtering and drying the leachate and the cobalt-nickel-manganese metal product, and specifically:

c1, when the cathode material is LCO or LMO, evaporating the filtrate obtained after filtering to dryness to obtain solid Li₂CO₃And drying filter residues to obtain a cobalt or manganese product, thereby realizing separation and recovery.

C2, when the cathode material is NCM, Li₂CO₃And manganese oxide, filtering and drying, recovering the manganese oxide after filter residues are dried, and recovering solid Li after filtrate is evaporated to dryness₂CO₃。

The invention accelerates the consumption of carbon in the electrode material and provides reaction heat by introducing the oxidizing atmosphere, simultaneously converts the cathode material of the battery into the metal simple substance and the metal oxide for recovery, and simultaneously achieves the effects of high reduction treatment of the electrode material and valuable metal recovery, thereby realizing the reduction treatment of valuable metal in the battery and waste battery.

In the first step, the oxygen-containing atmosphere roasting process mainly utilizes the rapid reaction of carbon and oxygen to consume carbon in the electrode material, thereby achieving the effects of carbon reduction and heat supply; decomposition of part of the cathode material occurs simultaneously; and in the second step of roasting, the oxygen is cut off, and simultaneously active gas capable of reacting with the residual carbon to generate reducing gas is introduced or the reducing gas is directly introduced, so that reducing atmosphere is mainly created to facilitate the reduction of the valuable metal and the removal of the residual carbon.

According to a preferred embodiment of the method for recovering spent lithium batteries and regenerating cathode active materials using step-by-step firing according to the present invention, the method further comprises:

D. oxidizing the recovered cobalt product or manganese product, and mixing with Li₂CO₃Mixing and grinding according to a certain proportion, and then regenerating LCO or LMO by adopting a solid phase sintering method.

The method comprises the first step of rapidly removing redundant carbon materials in the electrode active material by creating an oxygen-containing atmosphere, and the second step of realizing the reduction of metals by creating a reducing atmosphere. The carbon is removed through a series of reactions of the carbon, the heat required by the system reaction is provided, and the reduction of the reaction temperature of the systemThe energy consumption in the roasting process is reduced. Meanwhile, the removal of the graphite carbon simplifies the sorting process of the cathode and anode materials in the pretreatment process, and the proportion of the cathode and anode materials in the subsequent process is not required to be adjusted, so that the mechanized large-scale pretreatment of the lithium ion battery becomes possible. In the whole process, on the premise of not influencing the carbothermic reduction roasting process of metal, the removal of excessive carbon is accelerated by the first step of oxygen-containing atmosphere roasting, and reducing gas brought by the second step of reducing atmosphere roasting can also participate in metal reduction reaction, so that the simple solid-phase reaction is changed into the reaction of coexistence of solid phase and gas-solid phase, the reduction of metal is facilitated, and the post-treatment of a roasting product is facilitated. The post-treatment purification of the invention adopts a carbonic acid leaching method to carry out Li₂CO₃Purifying, introducing CO in the water immersion process of the roasted product₂Gas, will slightly dissolve Li₂CO₃Conversion to soluble LiHCO₃Realizing cobalt and manganese products and Li₂CO₃When the cathode material is a ternary material, the Li is separated by adopting a magnetic separation and carbonic acid leaching method₂CO₃Purifying by using CO₂Can convert slightly soluble Li₂CO₃Conversion to soluble LiHCO₃And separating the roasted solid-phase product by the magnetism of the metal cobalt and the metal nickel. The oxides of manganese remain in the filtered residue. The cobalt and nickel simple substances are magnetically separated out, and the product is obtained after drying). Li₂CO₃Conversion to LiHCO by carbonic acid leaching treatment₃Dissolving in aqueous solution, and subsequently obtaining Li by evaporating the filtered supernatant₂CO₃And (4) crystals. The post-treatment purification has the advantages that the separation is realized by a physical method, the acid consumption is almost not needed, and the secondary pollution and the reagent cost can be effectively reduced.

According to the preferable scheme of the method for preparing the cathode active material by recovering the waste lithium battery through step-by-step roasting, in the step A, the roasting gas in the oxygen-containing atmosphere not only comprises a pure oxygen atmosphere, but also comprises a mixed atmosphere of oxygen and inert gas or oxidizing atmosphere such as air; the gas for roasting in the reducing atmosphere is a single gas or a mixed gas of the single gases, and the single gas is water vapor or CO₂Isoenergetic reaction with carbon to form reducibilityActive gas of gas, or the single gas is CO, H₂And the like, and the reducing gas does not contain oxygen and can perform oxidation-reduction reaction with the electrode material under the roasting condition.

The waste lithium ion battery recycling and reducing technology can realize the recycling of valuable components in the battery, reduce carbon in electrode materials and provide reaction heat to reduce energy consumption in the roasting process. The effects of improving the reduction of carbon and simplifying the pretreatment process of the lithium ion battery are achieved while metal resources are recovered.

The invention not only expands the recycling method of carbon in the electrode material, but also provides a new mode for the mixed treatment of the cathode and the anode of the waste lithium ion battery.

Because the cathode material releases oxygen in the thermal decomposition process, and the decomposition of the cathode material and the further reduction of valuable metals are not facilitated due to excessively high oxygen partial pressure, the conventional reduction roasting method is generally carried out under oxygen-free conditions such as inert gas or vacuum pumping, but the problem that carbon in the electrode material cannot be effectively removed is caused. In order to solve the problem, reduction roasting of the electrode material is carried out in a water vapor atmosphere, carbon in the electrode material is effectively removed, and valuable metal is reduced. Therefore, the invention introduces oxygen to accelerate the gasification of carbon, and realizes the effective removal of carbon in the electrode material and provides energy for the reaction by step roasting and controlling the amount of the oxygen, and simultaneously does not influence the reduction of the valuable metal of the cathode. Experiments show that the decomposition of the cathode material and the reduction recovery of valuable metals can be realized by roasting step by step and effectively controlling the oxygen content, and carbon in the electrode material is removed, so that the energy consumption is saved.

The method for preparing the regenerated cathode active material by recovering the waste lithium battery through step-by-step roasting has the beneficial effects that:

according to the invention, carbon materials which are difficult to separate in the battery components are effectively removed and converted into reaction heat required in the roasting process, so that the high decrement ratio of carbon is realized; and a reduction way is added, so that the cathode material is fully reduced while carbon in the electrode material is removed, and finally the valuable metal of the cathode is recovered. The method can realize four effects of recovering metal resources, reducing carbon, and reducing water consumption and energy consumption. The method provides a new mode for the mixed treatment of the cathode and the anode of the waste lithium ion battery, realizes closed-loop recovery, has simple process and easy operation, can realize high-efficiency recovery and resource utilization of the waste lithium battery, and can be widely applied to the recovery of the retired lithium ion battery in the fields of new energy vehicles, energy storage and the like.

Drawings

FIG. 1 is a flow chart of a method for preparing cathode active materials by stepwise roasting and recycling waste lithium batteries according to the invention.

FIG. 2 is a pie chart of gas composition during step firing.

FIG. 3 is a bar graph of the metal recovery obtained after fractional calcination.

Detailed Description

The present invention will be further described with reference to the following examples.

Example 1, referring to fig. 1 to 3, a method for recovering a spent lithium battery to prepare a cathode active material by stepwise roasting, the method comprising the steps of:

discharging and disassembling a waste power battery pack to obtain a battery monomer and recycle part of valuable components;

step two, performing discharge treatment on the waste lithium ion battery monomer to release the residual electric quantity of the battery;

step three, mechanically crushing the discharged waste lithium ion battery to enable each component of the battery to be crushed into particles with different particle sizes so as to facilitate subsequent screening and separation;

and step four, screening the battery particles by using screens with different apertures to separate the copper foil, the aluminum foil and the electrode active material, and screening out the electrode active material.

And step five, collecting and treating the gas generated in the step three to step four and the roasting process.

Step six, roasting the screened electrode active material particles step by step, roasting the electrode active material particles in an oxygen-containing atmosphere, wherein an oxidation reaction of carbon and decomposition of part of cathode materials occur in the roasting process, and the oxidation reaction of the carbon realizes rapid decrement of the carbon and supply of decomposition reaction heat of the cathode materials so as to reduce valuable metals in the following process; cutting off oxygen after roasting in an oxygen-containing atmosphere is completed, and then roasting in a reducing atmosphere, wherein a carbon gasification reaction and a metal oxidation-reduction reaction continue to occur in the roasting process in the reducing atmosphere, and the carbon gasification reaction consumes carbon in the electrode material, so that the effect of improving the carbon decrement ratio is achieved; the metal redox reaction reduces the chemical valence of the nonferrous metal so as to facilitate the separation of the valuable metal; the gas-phase product in the roasting process is directly collected and treated by a tail gas treatment device;

seventhly, separating and purifying the solid-phase product after the step-by-step roasting, and specifically comprising the following steps:

b1, when the cathode material is lithium cobaltate or lithium manganate, adopting carbonic acid leaching method to Li₂CO₃Purifying to simultaneously realize cobalt or manganese metal products and Li₂CO₃Separating;

b2, when the cathode material is a nickel cobalt lithium manganate ternary material, performing magnetic separation and carbonic acid leaching on Li₂CO₃Purifying, and simultaneously mixing the cobalt and nickel simple substances with Li₂CO₃And separating the oxides of manganese, thereby recovering the elementary substances of cobalt and nickel.

Step eight, adding Li₂CO₃Filtering and drying the leachate and the cobalt-nickel-manganese metal product, and specifically:

c1, when the cathode material is LCO or LMO, evaporating the filtrate obtained after filtering to dryness to obtain solid Li₂CO₃Drying the filter residue to obtain a cobalt or manganese product, thereby realizing separation and recovery;

c2, when the cathode material is NCM, Li₂CO₃And manganese oxide, filtering and drying, recovering the manganese oxide after filter residues are dried, and recovering solid Li after filtrate is evaporated to dryness₂CO₃。

Step nine, oxidizing the recovered cobalt product or manganese productTreating with Li₂CO₃Mixing and grinding according to a certain proportion, and then regenerating LCO or LMO by adopting a solid phase sintering method.

In a specific embodiment, the gas for the oxygen-containing atmosphere calcination in the sixth step includes not only a pure oxygen atmosphere, but also a mixed atmosphere of oxygen and an inert gas, or an oxidizing atmosphere such as air; the gas for roasting in the reducing atmosphere is a single gas or a mixed gas of the single gases, and the single gas is water vapor or CO₂An active gas capable of reacting with carbon to generate a reducing gas, or the single gas is CO or H₂And the like, and the reducing gas does not contain oxygen and can perform oxidation-reduction reaction with the electrode material under the roasting condition.

The oxygen or air functions to rapidly oxidize the carbon material in the electrode material and provide reaction heat; inert gases such as nitrogen and argon are used to adjust the partial pressure of oxygen in the system.

The invention can mechanically crush the waste lithium ion battery after the brine discharge by using a crusher, and effectively separate the electrode material from the diaphragm and the current collector in the screening device by utilizing the difference of the ductility of different materials through the particle size difference. The pretreatment scheme does not need to manually sort the anode and cathode materials, does not need to allocate the proportion of the anode and cathode materials, has the advantages of simple operation and wide application range, and is beneficial to industrial large-scale treatment.

The pretreatment of the invention adopts a mechanical crushing and screening mode, and the separation of the cathode and the anode is not needed, thereby reducing the process cost and difficulty. The pretreatment method can be completed by utilizing industrially mature crushing and screening equipment, and is beneficial to large-scale commercialization and automatic application of the waste lithium ion battery recovery technology.

The invention effectively accelerates the carbon reaction and improves the decrement ratio of carbon. The method adopts oxidizing atmosphere and reducing atmosphere to roast step by step, utilizes a series of gasification reactions of carbon, particularly the existence of oxygen to accelerate the removal of the carbon, ensures that the carbon material in the battery can fully react, provides heat for the reaction, reduces the reaction temperature and saves the energy consumption. Effectively realize the reduction and utilization of carbon.

The invention fully reduces the valuable metal in the electrode material. By utilizing the reducibility of carbon and H in the electrode material₂And the reducibility of CO, fully reducing nonferrous metals. Compared with inert atmosphere or vacuum reduction roasting, the method has the advantages that gas-solid two-phase reaction is added in addition to single solid-phase reaction, so that the reaction is more sufficient. The obtained product can be cobalt, nickel metal, manganese oxide and Li₂CO₃And the like; LCO or LMO can also be obtained by regenerating a cathode active material, thereby realizing the recovery of higher value-added products. The post-treatment purification adopts a carbonic acid leaching method to separate and purify a solid-phase product, thereby greatly reducing the consumption of reagents and water and almost having no secondary pollution.

Example 2:

in this embodiment, a waste lithium cobaltate LCO battery is taken as an example for specific description. The LCO cells were first discharged through a 24 hour, 5 wt.% NaCl solution. And when the voltage is reduced to a safe range, mechanically crushing the LCO battery for 1min by using a crusher. After the crushing is finished, the diaphragm with the grain diameter larger than 0.450mm, the copper foil and the aluminum foil with the grain diameter of 0.355-0.450mm and the cathode and anode mixed active powder with the grain diameter smaller than 0.180mm are sieved according to the difference of the grain diameters. The cathode and anode mixed active powder with the particle size of less than 0.180mm mainly comprises 30.6 wt.% of C, 4.9 wt.% of Li and 39.5 wt.% of Co. Firstly, feeding the cathode and anode mixed active material into an air atmosphere roasting system for carrying out first-step roasting treatment (air enters the roasting system according to the ratio of O/C (1: 1), maintaining the circulation of the whole system, accelerating the removal of carbon and increasing the heat supply), and roasting for 0.5h at 800 ℃ in the atmosphere; then keeping the temperature constant, continuing the second roasting step, cutting off air and introducing steam (using liquid water and water H by injection pump)₂O/C2: 1 was injected into the firing system and water was vaporized in the firing furnace to achieve firing in a water vapor atmosphere), and firing was carried out in this atmosphere for 0.5 h. The gas product components are shown in FIG. 2, H₂2.3 percent of CO, 1.1 percent of CO₂16.9% by weight, N₂Accounts for 76.0 percent. The decrement of carbon is defined according to the ratio of the carbon content in the solid phase product reduced relative to the carbon content in the waste lithium ion battery before roasting to the carbon content in the waste lithium ion batteryIn comparison, the oxygen gas mixture roasting flow realizes a carbon reduction ratio of 76.5%. The solid product in the roasting process of the oxygen gas mixture is a cobalt simple substance and an oxide thereof and Li₂CO₃. The metal recovery rates by baking are shown in FIG. 3, and the recovery rates by baking of Co and Li were 88.2% and 70.0%, respectively. After the solid phase product is cooled to room temperature, Li is purified by adopting a carbonic acid leaching method₂CO₃Simultaneously realizing the separation of the product of the catalyst and cobalt, and drying the obtained filtrate to obtain Li₂CO₃And (4) drying the crystal and filter residue to obtain a cobalt product. The obtained cobalt product is firstly roasted for 0.5h at 800 ℃ in the air atmosphere for oxidation treatment, and the obtained Co₃O₄Then with Li₂CO₃Adjusting the molar ratio of Co to Li to be 1:1.05, then sending the mixture into an air atmosphere furnace for solid-phase roasting, roasting for 13 hours at the temperature of 850 ℃, and carrying out LCO regeneration treatment.

Example 3:

the cathode and anode mixed active material described in example 2 is firstly sent into an air atmosphere roasting system to be roasted for the first step (air enters the roasting system according to the ratio of O/C to 2:1, the circulation of the whole system is maintained, the accelerated removal of carbon is realized, and the heat supply is increased), and the mixed active material is roasted at 800 ℃ in the atmosphere; after the carbon material is completely consumed, the second roasting step is continued while maintaining the temperature, the air is cut off, and a reducing gas (water gas (H) is introduced₂Mixed with CO) according to H₂&Introducing CO/Co of 1.2:1 into a roasting system, creating a reducing atmosphere), and continuously roasting in the atmosphere to realize the reduction of the metal oxide. In the first step, sufficient oxygen is adopted for roasting, so that the reaction time can be further reduced, the loss of valuable metals in the reaction process is reduced, a higher carbon reduction ratio is realized, and the product purity is improved; the second step adopts the mode of directly feeding reducing gas, so that the reduction of metal can be more thorough, and the product purity is improved. The solid product after roasting is a cobalt simple substance and Li₂CO₃. After the solid phase product is cooled to room temperature, Li is purified by adopting a carbonic acid leaching method₂CO₃Simultaneously realizing the separation of the product of the catalyst and cobalt, and drying the obtained filtrate to obtain Li₂CO₃And (4) drying the crystal and filter residue to obtain a cobalt product. What is needed isThe obtained cobalt product is firstly roasted for 0.5h at 800 ℃ in the air atmosphere for oxidation treatment, and the obtained Co₃O₄Then with Li₂CO₃Adjusting the molar ratio of Co to Li to be 1:1.05, then sending the mixture into an air atmosphere furnace for solid-phase roasting, roasting for 13 hours at the temperature of 850 ℃, and carrying out LCO regeneration treatment.

Example 4:

the cathode and anode mixed active material of the embodiment 2 is firstly sent into an oxygen-rich atmosphere roasting system for carrying out the first-step roasting treatment (oxygen enters the roasting system according to the O/C (2: 1), the circulation of the whole system is maintained, the accelerated removal of carbon is realized, the heat supply is increased), and in the atmosphere, roasting is carried out at 800 ℃, and the gas circulation in the roasting system can be reduced by using pure oxygen, so that the gas carrying loss of valuable metals is reduced, and the roasting recovery rate is improved; after the carbon material is completely consumed, the second roasting step is continued while keeping the temperature unchanged, oxygen is cut off, then reducing gas (pure CO gas is introduced into a roasting system according to the ratio of CO/Co being 1.2:1 to create reducing atmosphere), roasting is continued in the atmosphere to realize reduction of metal oxide, and the introduction of impurities can be reduced by adopting the pure gas, so that the product purity is improved. The solid product after roasting is a cobalt simple substance and Li₂CO₃. After the solid phase product is cooled to room temperature, Li is purified by adopting a carbonic acid leaching method₂CO₃Simultaneously realizing the separation of the product of the catalyst and cobalt, and drying the obtained filtrate to obtain Li₂CO₃And (4) drying the crystal and filter residue to obtain a cobalt product. The obtained cobalt product is firstly roasted for 0.5h at 800 ℃ in the air atmosphere for oxidation treatment, and the obtained Co₃O₄Then with Li₂CO₃Adjusting the molar ratio of Co to Li to be 1:1.05, then sending the mixture into an air atmosphere furnace for solid-phase roasting, roasting for 13 hours at the temperature of 850 ℃, and carrying out LCO regeneration treatment.

The invention has the same applicability to lithium cobaltate batteries, lithium manganate batteries, lithium nickelate batteries, cobalt-nickel-manganese ternary batteries and cobalt-nickel-aluminum ternary batteries.

The embodiments described above are only a few embodiments of the present invention, and not all embodiments of the possible implementations of the present invention. Any non-inventive changes, which may be made by a person skilled in the art without departing from the technical idea of the invention described above, should be considered to be included in the scope of the claims of the present invention.