BG113822A - Method and device for recycling lithium ion batteries - Google Patents

Abstract

The invention relates to a method and device for exfoliating the black mass (BM) from the conductors of spent lithium ion batteries (LIBs) and an exfoliating reactor (ER),which solve the task of separating the ferrous mass (PM) from the metal conductors, working with a specially designed non-toxic and environmentally water-based exfoliating agent (EA).Through the exfoliation method and the special ecological composition of the exfoliating agent EA, which is water-based, effectively solves the problem of separating the PM from the metal conductors without compromising their integrity or altering and destroying the crystalline structure of the active electrode materials AEM used. This allows their direct use or, after minimal compositional adjustments, their effective reuse as AEMs in new LIBs. The method provides fully closed-loop use of primary raw materials repeatedly and highly efficiently ensuring the electrochemical performance of LIBs.

Description

Method and device for recycling lithium-ion batteries

Field of technology

The present invention relates to a method for exfoliating the black mass (CM) from the conductors of disused lithium-ion batteries (LIB) and an exfoliating reactor (ER) device, which together solve the task of separating the black mass (CM) from the metal conductors, working with a specially created for the purpose non-toxic and environmentally friendly water-based exfoliating agent (EA).

. Prior art

The widespread introduction of portable electronic devices increasingly requires the use of appropriate power systems that can meet the growing energy demands in this area.

LIBs are the only source that can cover the growing energy needs at an acceptable energy density-to-weight ratio. On the other hand, the world is paying more and more attention to ecology and green technologies, which impose a certain way of thinking and repeated use of active electrode materials (AEM), energy carriers in chemical current sources.

A large amount of LIBs are discarded every day, which, while working, are an indispensable source of energy, but after the end of their life cycle, they represent a problem on the one hand, due to the oxides or phosphates of toxic heavy metals, such as nickel, cobalt, manganese, aluminum and iron, which on the other hand are extremely valuable exchange raw materials with high value, of interest to the electrical and metallurgical industries. Nickel, cobalt and manganese are the main alloying additives to all types of special and tool steels. In addition, LIBs that have partially lost their electrochemical characteristics are an invaluable starting material for the production of new LIBs. At the current stage of economic development, LIB recycling represents a huge challenge and is a key element in the rapidly gaining momentum of the circular economy. The extraction, processing and recycling of active electrode materials AEM, differing only partially in their elemental composition and electrochemical characteristics from newly synthesized ones, allows for a more than fourfold reduction in energy and clean water costs for the production of new LIBs [1-9].

LIBs consist of an aluminum conductor coated with an active cathode material (ACM), which is lithium nickel manganese cobalt oxide (Li-NMC), lithium nickel cobalt aluminum oxide (Li-NCA), lithium iron phosphate (LFP) or a mixture thereof, and a copper conductor coated with an active anode material (AAM), which is a mixed carbon composite including graphite and various carbon additives, such as graphene, fullerenes, carbon nanotubes, and recently silicon nanoparticles, in order to enhance the specific characteristics of the AAM. The polymer PVdF (poly(vinylidene fluoride)) is used as a binder for the production of both electrodes, cathode and anode. The latter is widely used in modern electronics and instrument making due to its high stability in a wide temperature range (from -25°C to +150°C) and excellent chemical resistance to organic solvents, acids and bases [6]. Poly(vinylidene fluoride) PVdF is difficult to remove from the active electrode mixture, cathode ACM or anode AAM, which constitute the so-called black mixture HM, and this makes it difficult to develop a suitable technology for the separation (exfoliation) of HM from metal conductors [1-9].

The methods described in the literature for recycling end-of-life LIBs combine mechanical and chemical processes. Mechanical processes refer to the disassembly of the battery module to remove the packaging and control electronics, followed by separation of the pack into individual cells, removal of the residual electrical charge and crushing (grinding) of the single cell, the so-called shredding process [1,7,9] and obtaining shredded black starting mass SHIM. Chemical processes for processing shredded black starting mass SHIM obtained from shredded lithium-ion cells include three different approaches - acid treatment [1,2,5,6.7], alkaline treatment [1,3,4] or treatment with organic solvents [8]

Acid treatment with strong acids (sulfuric, nitric, hydrochloric acids or a suitable two- or three-component mixture of them) leads to complete chemical dissolution of both the metal oxide part of the ICHM (ACM) and the metal conductors. The carbon component is separated as a precipitate in this process, which is in an amount of about 10-20% of the weight of the ICHM. All nickel, manganese, cobalt, aluminum, copper, lithium and iron ions that are subject to recycling go into solution. The process is carried out carefully, under specially selected conditions - concentration, time and temperature, in hermetically sealed vessels (autoclaves and reactors), as poisonous chlorine and/or nitrogen oxides are released. The final product is a mixture of chemical compounds of the starting metals - nickel, manganese, cobalt, aluminum, copper, lithium and iron in the form of sulfates, chlorides, nitrates or phosphates, depending on the acid used). Separating the individual components of this mixture is a huge challenge and requires the use of complex and sophisticated chemical equipment and the creation of a special systematic process for separating the listed chemical elements one by one. The process is long, complex and energy-intensive.

Acid treatment with relatively weak organic acids, for example acetic acid [6] requires the same complex technological scheme, and the final product is again the same complex multicomponent mixture of metal ions, nickel, manganese, cobalt, aluminum, lithium, copper and iron salts of the acids used. Here the conditions are "softer" and the environment is not so aggressive, but this cq is reflected in the time required, which is compensated by increasing the operating temperature of the process.

The use of both strong mineral acids and weak organic acids brings the process closer to electroplating production with all the resulting consequences and difficulties of a technological and environmental nature, such as the use of complex and expensive purification equipment and the separation of a large amount of washing water containing ions of heavy metals such as nickel, manganese, cobalt, aluminum, copper and iron.

Alkaline treatment with a strong base (potassium hydroxide or potassium hydroxide) [1,3,4] aims to again destroy the connection of the ICHM with the conductor and release it. In this case, the ICHM itself is not attacked, which is a significantly gentler process, and the strong bases used interact with the conductors - aluminum on the cathode and copper on the anode. Both metals are unstable in an alkaline environment and dissolve, especially aluminum, which releases stoichiometric amounts of hydrogen, placing the process in the category of a highly fire and explosion-hazardous process, requiring special explosion-proof design of all equipment and special fire protection measures of the highest class for the premises.

A new promising method for separating ACM from the aluminum conductor is by dissolving the PVdF poly(vinylidene fluoride) bonding polymer with various specially selected organic solvents, such as NMP (N-methyl pyrrolidine), DMA (Ν,Ν-dimethyl formamide) or a mixture of them. However, these two solvents are highly toxic and harmful to operators, environmentally hazardous and quite expensive. Regulatory authorities strongly restrict their industrial applications and encourage their replacement with safer alternatives. Bay Y. et al. [8] used TER (triethyl phosphate), which is significantly less toxic than the above-listed solvents, to recover AEM by dissolving the PVdF bonding polymer. The results show that AEM is separated from the conductors without problems and without compromising their physical characteristics, crystal structure and electrochemical characteristics; the recovered aluminum and copper foil are clean without any traces of corrosion, and the polymer binder can be recovered by phase separation. Of course, the proposed TEP turns out to be quite toxic, both to humans and to the environment.

The analysis of the literature and the proposed solutions show that the recycling of LIB is a complex task and requires a comprehensive and non-standard approach.

Technical essence of the invention

The present invention relates to a method for exfoliating the black mass (CM) from the conductors of disused lithium-ion batteries (LIB) and a device of an £ exfoliating reactor (ER), which together solve the task of separating the black mass (CM) from the metal conductors, working with a specially created for the purpose non-toxic and environmentally friendly water-based exfoliating agent (EA).

According to the invention, the specially developed water-based exfoliating agent EA, which is used in the exfoliating reactor EP, is environmentally friendly, non-toxic, does not cause allergic reactions upon contact with human skin and does not have a harmful effect upon possible inhalation due to the low vapor pressure. The exfoliating agent is an aqueous solution of a multicomponent system, including a selected cocktail of cations (Li ⁺ , Na ⁴ . K ⁺ , Mg ²⁺ , Ca ²⁺ , Zn ²⁺ , NH4 ⁺ ) and anions (FhPOc, HPOd ^2- , PO? , ClOd, NCh', NO2-, HCO3. HSO3·, CO3 ² ', SO3 ² ', SO4 ² ', OH', F', Cl', Br, I ) and additional modifiers and regulators of acidity and pH, such as H2O2 and NH4OH, with a total concentration of 0.400 to 3.000 mol/L.

In particular, EA is in the form of an aqueous solution with the following ion concentration (in mol/L): Li ⁺ , Na ⁺ , K ⁺ from 0.100 to 1.250; Mg ²⁺ , Ca ²⁺ , Zn ²⁺ from 0.000 to 0.400; NH4 ⁺ from 0.000 to 0.400; H2PO ₄ -, HPOd ² ', POL from 0.050 to 0.300; Cl2 from 0.050 to 0.150; NO ₃ ', NO _? from 0.100 to 0.350; HCO3', HSO3-, CO3 ² ', SO3 ² ', SO?' from 0.000 to 0.050; OH from 0.000 to 0.050; F', CT, Bg, D from 0.100 to 0.450, and H2O2 and NH4OH in a concentration of 0.050.

According to one embodiment of the invention, EA is in the form of an aqueous solution with pH = 7. with the following ion concentration (in mol/L): Li ⁺ , Na ⁺ , K ⁺ - 0.100: H2PO4·, HPO4 ² ' , PO4 ³ - - 0.050; CIO4- - 0.050; ΝΟ ₃ -, NCV - 0.100; F, CL, Br, Γ - 0.100, and H ₂ O ₂ and NH ₄ OH in concentration 0.050.

According to a second embodiment of the invention, the EA is in the form of an aqueous solution with pH < 4.5, with the following ion concentration (in mol/L): Li ⁺ , Na ⁺ , K ⁺ - 0.150; H2PO4 , HPCL ² ', PO4 ³ ' - 0.100; CIO4- - 0.100; NO ₃ , NO ₂ - 0.150; HCO3, HSOr, CO ₃ ² ', SO3 ² ; SO4 ² '0.050;F', Cl·. Br, L - 0.150, and H2O2 and NH4OH in a concentration of 0.050.

According to a third embodiment of the invention, EA is in the form of an aqueous solution with pH = 6.5-7.5, with the following ion concentration (in mol/L): Li ⁺ , Na ⁺ , K ⁺ - 0.350; Mg ²⁺ , Ca ²⁺ , Zn ²⁺ - 0.100; NH4 ⁺ - 0.050; H2PO4-, HPO4 ² ', PO4 ³ ' - 0.100; C1O4- - 0.100; NO ₃ ', NCb'0.100;HCO3', HSO3-, CO3 ² -, SO3 2 -, SO4 ^{2 -} 0.050; OH' - 0.050; F', Cl, Br, G - 0.350, and H2O ₂ and NH ₄ OH in a concentration of 0.050.

According to a fourth embodiment of the invention, E A is in the form of an aqueous solution with pH > 9.5, with the following ion concentration (in mol/L): Li ⁺ , Na ⁺ , K ⁺ - 1.100; Mg ²⁺ , Ca ²⁺ , Zn ²⁺ - 0.400; NH4 ⁺ - 0.050; H2PO4-, ΗΡΟ4 ² ', PO4 ³ - 0.100; C102 - 0.100; ΝΟ3, Ο ΝΟ ₂ - - 0.100; OH ^- - 0.050; F', Cl', Br, Γ - 0.150, and H2O2 and NH4OH in a concentration of 0.050.

According to a fifth embodiment of the invention, EA is in the form of an aqueous solution with pH = 7, with the following ion concentration (in mol/L): Li ⁺ , Na ⁺ , K ⁺ - 1.250; Mg ²⁺ , Ca ²⁺ , Zn ²⁺ - 0.400; NH4 ⁺ - 0.100; H2PO4-, HPO4 ² ', PO4 ³ ' - 0.100; C104 - 0.300; NO ₃ \ NO2 - 0.350; F', Cl', Br, G - 0.450, and H2O2 and NH ₄ OH in a concentration of 0.050.

Depending on the concentration and composition of the EA used, it is possible to selectively exfoliate the HM initially only from the copper current conductor - the anode. For example, when using an EA with the composition: Li ⁺ , Na ⁺ , K ⁺ - 0.350; Mg ²⁺ , Ca ²⁺ , Zn ²⁺ - 0.100; NH4 ⁺ - 0.050; H2PO4-, HPO4 ² -, PO4 ³ - - 0.100; C1O4- - 0.100; NO3, NO2 - 0.100; HCO3', HSO3, CO3 ² ', SO3 ² ·, SO4 ² - 0.050: OH - 0.050; F; CL, Br, I - 0.350, and H ₂ O ₂ and NH ₄ OH in a concentration of 0.050, with a total concentration of 1.2 mol/L, pH = 8.5 and a temperature of 50°C, pieces of copper foil are first quantitatively separated from the reactor by simple precipitation. The released black anode mass, which is a mixture of graphite and carbon additives, is removed from the reactor after washing. Then the process continues with the exfoliation of the CM of the other electrode - the aluminum cathode, which contains the metal oxides Li-NMC, Li-NCA, LFP or a mixture of them. At this stage, depending on the temperature (>50°C), the pH of the solution (pH > 9.5) and the concentration of EA (1.2 mol/L), a part of the aluminum foil can also be dissolved in an amount of up to 20%.

The reactor is a cylindrical vessel into which the shredded lithium-ion cells and EA enter from above through nozzles located on the lid. Their mixing takes place in a hopper located directly under the lid and from there the working mass falls into a perforated drum. Mechanical stirring of the mixture is carried out by a propeller stirrer. In addition, a compressor supplies an appropriate amount of gas (air, nitrogen, argon-hydrogen mixture (95/5%), carbon dioxide or carbon dioxide/air) to assist in homogenizing the mixture. The EP exfoliation reactor is hermetically sealed, which allows its operation to be controlled and managed during the entire technological process - without pressure, under pressure or at reduced pressure. To accelerate the exfoliation up to four times, four powerful industrial ultrasonic emitters are placed at the bottom of the reactor. The removal of FM from the current conductors is carried out at room temperature for about 60 hours. Increasing the temperature to 50°C leads to a twofold reduction in the processing time, while increasing the concentration of Li ⁺ , Na ⁺ H K ⁺ ions in the composition of EA to 1.250 mol/L, at a temperature of 20°C, the required time is less than 8 hours. After the end of the process, the resulting suspension of CM and EA is discharged through a nozzle located at the bottom of the reactor and falls into a precipitator, where CM is separated as a compact sediment, and EA is returned for reuse and separation of CM from a new portion of current conductors. The microprocessor control system ensures the proper course of this complex physicochemical process, which controls the temperature in the reactor, the stirring speed and the concentration of the suspension of EA and CM. The amount of separated CM is also controlled based on the amount of shredded mass input, the amount of separated CM and other technological parameters are determined. The exfoliation process is periodic, i.e. After a certain treatment time, the perforated drum is removed from the reactor and the pieces of copper and aluminum foil are separated from it, as pure metals (with over 99.9% purity), for subsequent reuse.

According to another embodiment of the invention, the reactor can also be installed at a certain angle (from 3° to 89°), in particular within the range of 25° to 65°, which allows the process of exfoliation of FM from the current conductors of disused LIBs to proceed with reduced treatment time, due to improved hydrodynamics and under controlled pressure conditions (normal, increased or decreased).

The reactor design and the EA used allow for effective separation of HM from the carrier conductors in a safe manner. The purity of the final products obtained - aluminum foil and a mixture of AKM (Li-NMC and/or Li-NCA and/or LFP), separated during the processing of the aluminum conductors of LIB, on the one hand, and separated copper foil from the mixture of graphite and carbon additive from the processing of the copper conductors on the other, makes them suitable for reuse as starting raw materials for the production of new LIBs or for other processing.

Explanation of the attached figures

Figure 1 is a diagram of a reactor for exfoliating FM from the conductors of disused LIBs, according to the invention.

Figure 2 presents the results of electrochemical tests of ACM recycled according to the utility model. (A) Discharge-charge cycles of recycled AEM tested in a standard CR2032 type LIB. (B) First discharge-charge curves of recycled AEM in a standard CR2032 type cell. (C) Discharge-charge curves of recycled AEM at different current modes in a standard CR2032 type cell. (D) Cyclicity of recycled AEM tested in a standard CR2032 type cell

Examples of implementation of the invention

The invention is illustrated by the following examples, which are not intended to limit it:

Example 1. The scheme of a reactor for exfoliation of used LIBs presented in Figure 1 includes: a housing (1); nozzles (2) and (3) located on the cover (4), through which the shredded lithium-ion cells and EA enter; a hopper (5) located immediately under the cover (4), where the LIB and EA waste are mixed and fall into a perforated drum (6) equipped with a propeller agitator (7); a compressor (8) supplying an appropriate amount of gas to assist in homogenizing the mixture; two powerful industrial ultrasonic emitters (9) located at the bottom of the reactor to accelerate the exfoliation process; a nozzle (10) located at the bottom of the reactor, from where the suspension of CM and EA after the end of the process is removed; a settler (11) for CM; a three-way crane (12) for returning EA from the settler (11) to the reactor for reuse; and the microprocessor control system (13).

Example 2. When changing the composition of the exfoliating agent and the temperature of the process, the time for removal and separation of HM from the conductors changes. For example, when using an exfoliating agent with the composition: Li ⁺ , Na ⁺ , K ⁺ 0.100; Η2ΡΟ4·, ΝΡΟ4 ² -, ΡΕΧ ³ ' - 0.050; ΣΙΟ4- - 0.050; NO ₃ , NO/ - 0.100; F', CP, Br, Γ - 0.100, and Ν2Ο2 in a concentration of 0.050 (in mol/L), the process is carried out at a temperature of 20°C for 60 hours. By lowering the pH of EA below 4.5 (composition: Li ⁺ , Na ⁺ , K ⁺ - 0.150; H2PO4·, HPO4 ² -, PO4 ³ · - 0.100; С1О4 - 0.100; NO ₃ ', NO ₂ - - 0.150; HСО3', HБО3', СО3 ² ', БО3 ² ' , SO4 ² · - 0.050; F', СГ, Br, I - 0.150, and H2О2 in a concentration of 0.050 (in mol/L) at the same temperature, the time required for the separation of the individual components of the CM is 36 hours. Increasing the temperature to 50°С leads to a twofold decrease in the processing time, while increasing the concentration of Li ⁺ , Na ⁺ and K ⁺ ions in the composition of EA to 1.250 mol/L (composition: Li ⁺ , Na ⁺ , K ⁺ - 1.250; Mg ²⁺ , Ca ²⁺ , Zn ²⁺ - 0.400; NH4 ⁺ - 0.100; H2PO4-, HPO4 ² ', PO4 ³ - - 0.100; С1О ₄ - - 0.300; NO3, NCL' - 0.350; F , Cl', Br, I - 0.450, and H2O2 in concentration 0.050), at a temperature of 20 °C the time required is less than 8 hours.

Example 3. Electrochemical tests of cathode material obtained by exfoliation with EA in the reactor according to the invention.

The active cathode material obtained by exfoliation with EA in the reactor according to the invention was tested for the manufacture of a standard CR2032 cell. The results obtained, presented in Figure 2, show that the recycled AEM exhibits almost 75% of the initial capacity of a freshly synthesized (not worked) active electrode material, a mixture of lithium nickel manganese cobalt oxide and lithium cobalt oxide.

Claims (8)

I. Reactor for exfoliating the black mass from the conductors of used lithium-ion batteries, characterized in that it includes: a housing (I), nozzles (2) and (3) located on the cover (4), through which the shredded lithium-ion cells and the exfoliating agent enter, a hopper (5) located immediately under the cover (4), where the waste from lithium-ion batteries and the exfoliating agent are mixed and fall into a perforated drum (6) equipped with an impeller agitator (7), a compressor (8) supplying gas to assist in homogenizing the mixture, two powerful industrial ultrasonic emitters (9) located at the bottom of the reactor to accelerate the exfoliation process, a nozzle (10) located at the bottom of the reactor, from where the suspension of black mass and the exfoliating agent after the end of the process is removed, a settler (II) for the black mass, a three-way valve (12) for returning the exfoliating agent from the precipitator (11) to the reactor for reuse, and the microprocessor control system (13). 2. Reactor for exfoliating the black mass from the conductors of used lithium-ion batteries, according to claim 1, characterized in that the axis of rotation of the drum is less than 89° and greater than 3° relative to the horizontal. 3. Exfoliating agent for use in the reactor according to claim 1, characterized in that it is an aqueous solution with the following ion concentration (in mol/L): Li ⁺ , Na ⁺ , K ⁺ from 0.100 to 1.250; Mg ²⁺ , Ca ²⁺ . Zn ²⁺ from 0.000 to 0.400; NH4 ⁺ from 0.000 to 0.400; H2PO ₄ -, HPO ₄ ² ', PO4 ³ ' from 0.050 to 0.300; C1O4- from 0.050 to 0.150; NOy, NO< from 0.100 to 0.350; HCO3, HSO ₃ -, CO3 ² ', SCh ² ', SO4 ² from 0.000 to 0.050; OH from 0.000 to 0.050; F', Cl·, Br, l· from 0.100 to 0.450, and H2O2 and NH4OH in a concentration of 0.050. 4. Exfoliating agent according to claim 3, characterized in that it is in the form of an aqueous solution with pH = 7, with the following ion concentration (in mol/L): Li ⁺ , Na ⁺ . K ⁺ - 0.100; H2PO4-, HPO4 ² ', PO4 ³ ~ - 0.050; ClO ₄ ' - 0.050; NO ₃ , NO ₂ ' - 0.100; F', Cl·, Br, l· - 0.100, and H ₂ O ₂ and NH ₄ OH in a concentration of 0.050. 5. Exfoliating agent according to claim 3, characterized in that it is in the form of an aqueous solution with pH < 4.5, with the following ion concentration (in mol/L): Li ⁺ , Na ⁺ , K ⁺ - 0.150; H2PO4', HPO4 ² ', PO4 ³ - 0.100; C1O ₄ - - 0.100; NO3·, NOy . 0.150; HCO3, HSO3-, CO3 ² ', SO3 ² -, SO4 ² - - 0.050; F', CF, Br, I - 0.150, and H2O ₂ and NH4OH in a concentration of 0.050. 6. Exfoliating agent according to claim 3, characterized in that it is in the form of an aqueous solution with pH = 6.5-7.5, with the following ion concentration (in mol/L): Li ⁺ , Na ⁺ , K ⁺ - 0.350; Mg ²⁺ , Ca ²⁺ , Zn ²⁺ - 0.100; NH4 ⁺ - 0.050; H2P() ₄ , HPO 4 2 ', Ρ() ₄ ³ - 0.100; CIO4- - 0.100; ΝΟ 3 , ΝΟ 2 - 0.100; ΝΟ ₃ , ΝΟ ₂ - 0.100; ^ΝΟ 3 ', HSCh'. Ο3 ² , SO3 ² -. SO4 ² '0.050; OH ^- - 0.050; F', CF, Br, F - 0.350, and H2O ₂ and NH ₄ OH in a concentration of 0.050. 7. Exfoliating agent according to claim 3, characterized in that it is in the form of an aqueous solution with pH > 9.5, with the following ion concentration (in mol/L): Li ⁺ , Na ⁺ , Κ ⁺ - 1.100; Mg ²⁺ , Ca ²⁺ , Zn ²⁺ - 0.400; NH4 ⁺ - 0.050; H2PO ₄ ', HPO ₄ ² ', PO4 ³ - - 0.100; CIO4- - 0.100; NO ₃ ', NO ₂ ' - 0.100; OH - 0.050; F', CF, Br, F - 0.150, and H ₂ O ₂ and NH ₄ OH in a concentration of 0.050. 8. Exfoliating agent according to claim 3, characterized in that it is in the form of an aqueous solution with pH = 7, with the following ion concentration (in mol/L): Li ⁺ , Na ⁺ , K ⁺ - 1.250; Mg ²⁺ , Ca ²⁺ , Zn ²⁺ - 0.400; NH4 ⁺ - 0.100; H2PO ₄ ', HPO ₄ ² '. PO4 ³ '0.100; CIO4- - 0.300; NO ₃ , NO ₂ - - 0.350; F', CF, Br, 1 - 0.450, and H ₂ O ₂ and NH ₄ OH in a concentration of 0.050.