RU2789852C1 - Method for processing lithium-ion batteries with obtaining positive electrode components of alkaline batteries - Google Patents

Abstract

FIELD: waste processing and disposal.

SUBSTANCE: invention relates to the fields of waste processing and disposal, as well as electrical engineering, and can be used in industry for processing and recycling lithium-ion batteries and obtaining positive electrode components for alkaline nickel-cadmium batteries. The method for processing lithium-ion batteries comprises the following steps: discharging spent lithium-ion batteries in solution, crushing and mechanically separating into several fractions that differ in particle size, density and chemical composition; get graphite powder and powder of cobalt, lithium, nickel, manganese, aluminum oxides; the resulting graphite powder is cleaned from traces of metals and used as an additive to the positive electrode of an alkaline battery; the obtained powder of oxides of cobalt, lithium, nickel, manganese, aluminum is exposed to an aqueous solution of sulfuric acid, then precipitation and separation of a part of manganese in the form of manganese (IV) oxide, precipitation and separation of a mixture of hydroxides of nickel (II), cobalt (II), aluminum and manganese residue; a mixture of nickel (II), cobalt (II), aluminum and manganese hydroxides is used as a nickel- and cobalt-containing mixed component of the positive electrode of an alkaline battery.

EFFECT: improving the efficiency and safety of lithium-ion battery recycling.

1 cl, 1 ex

Description

The field of technology to which the invention belongs

The invention relates to the fields of waste processing and disposal, as well as electrical engineering, and can be used in industry for processing and recycling lithium-ion batteries and obtaining positive electrode components for alkaline nickel-cadmium batteries.

State of the art

Lithium-ion batteries are the most energy-intensive and energy-efficient among secondary current sources, which determines their widespread use in household and industrial devices, for electric vehicles. In such batteries, during charging and discharging, lithium ions are extracted from one electrode, migrate through the electrolyte, and are introduced into another electrode (Modern electrochemical energy storage systems / T. L. Kulova, et al. // Kimya problemləri, 2018, No. 1. P. 9-34). The composition of the materials used for batteries varies depending on their purpose and manufacturer. As positive electrodes, composites of mixed oxides of lithium, cobalt, nickel, manganese, aluminum or iron and lithium phosphate with electrically conductive carbon additives and a polymer binder, fixed on aluminum foil, are used. The main component of the negative electrode is graphite or some lithium, fixed on copper or (less often) aluminum foil. The electrodes are separated by a dielectric polymer separator impregnated with a liquid solution of a lithium salt in organic solvents that conducts current, or a polymer with lithium-ion conductivity. After completion of operation, undamaged lithium-ion batteries are considered waste of hazard class II (FKKO code 48220131532 (Order of Rosprirodnadzor dated May 22, 2017 N 242 (as amended on October 4, 2021) "On approval of the Federal classification catalog of waste")) and are subject to disposal.

Nickel-cadmium batteries for industrial and special purposes are distinguished by high service and storage life, long-term storage of the accumulated charge, reliability at low temperatures, low cost, closed cycles for the disposal of used devices, the production of new products and their application, so they are still one of the most common secondary power sources. In such batteries, during charging and discharging, hydroxide ions are released from one electrode, migrate through the electrolyte, accumulate on another electrode (Modern electrochemical energy storage systems / T. L. Kulova, et al. // Kimya problemləri, 2018, No. 1. C 9-34). As the main component of the mass of the positive electrode, nickel oxide hydrate (nickel(II) hydroxide) is used, additives of graphite, barium sulfate, cobalt(II) hydroxide, a binder are used (Dasoyan M.A., Novodereyazhkin V.V. and Tomashevsky F. F. Production of electric accumulators, Moscow, "Vysshaya Shkola", 1970, pp. 294-301). The main component of the negative electrode is cadmium oxide or hydroxide. The electrolyte is alkaline aqueous solutions containing sodium, potassium and lithium hydroxides. After completion of operation and separation of the electrolyte, nickel-cadmium batteries are considered waste of the III hazard class (FKKO code 92012002523 (Order of Rosprirodnadzor dated May 22, 2017 N 242 (as amended on October 4, 2021) "On approval of the Federal classification catalog of waste")).

The presence in lithium-ion and alkaline batteries of the same components, namely graphite and valuable cobalt and nickel, allows the possible processing of lithium-ion batteries, which are waste of hazard class II, combined with the subsequent production of components of the positive electrode of alkaline batteries.

A known method for processing waste batteries (WO2011113860A1, 09/22/2011), including the following steps: sorting batteries into groups according to varieties; separation of disk batteries; disassembly of lithium-ion batteries; grinding of accumulators with separation into heavy solid fraction and dust; dust capture and sorting by particle size; separation of heavy fraction particles by density; removal of ferromagnetic material by magnetic separation of particles moved by the conveyor; transfer of separation products to a purification or remelting process to recover reusable materials. Increasing the degree of recovery of reusable waste battery materials with minimal adverse environmental impact is the technical result of the claimed invention. Sorting of spent current sources into lead-acid, nickel-cadmium, nickel-metal hydride, mercury-containing, lithium-ion batteries, lithium primary current sources and separation of small disk cells, regardless of variety, are envisaged. A feature of the invention is that as a result of the processing of lithium-ion batteries, particle fractions are obtained that differ in density, size and chemical composition, which corresponds to mechanical separation into concentrates: light plastic and cardboard, heavy plastic and structural metals, iron flakes, powder with copper and cobalt compounds. A mixture of lightweight plastics and cardboard is proposed to be added to the process of processing nickel-metal hydride batteries to reduce energy costs at a nickel-smelting plant, which will be a recipient of nickel-containing waste.

However, the authors do not pay attention to the fact that lithium-ion batteries entering for processing may contain an excess charge. If charged batteries are subjected to mechanical destruction, they may ignite and explode. It is also not taken into account that modern lithium-ion batteries with oxide positive electrodes contain nickel, manganese and aluminum in addition to cobalt, respectively, the separation of these metals is not considered, and the use of compounds of these metals is also not considered.

A known method of recycling lithium-containing waste in the form of batteries (RU2676806C1, 01/11/2019), which includes the discharge of lithium batteries using a discharge unit; grinding and alkali treatment; purification of the liquid fraction with further production of lithium carbonate; drying, magnetic separation and hydrolysis of the solid fraction; filtration; ammonia treatment of the filtrate to remove iron and chromium; precipitation from the purified filtrate, filtration and drying of gallium hydroxide. For disposal according to this approach, lithium batteries of the Li / SOCl ₂ (lithium-thionyl chloride), Li / SO ₂ Cl ₂ (lithium-sulphuryl chloride), Li / SO ₂ (lithium-sulfur dioxide) systems are used, which occupies only a small part of the total volume lithium-containing current sources.

However, this method involves the use of a discharge installation, respectively, an individual connection to the detachable mechanisms of each current source that requires a discharge. In the conditions of processing a large number of batteries of different sizes, this stage will be characterized by low productivity. In addition, this method is limited in terms of the type of lithium power sources that can be recycled and does not include the recycling of lithium-ion batteries.

To discharge lithium-ion batteries, a common technique is that the batteries are kept for a day in aqueous solutions of sodium chloride, potassium chloride, sodium nitrate, manganese sulfate, magnesium sulfate, or iron sulfate (Pražanová, A. Literature review, recycling of lithium-ion batteries from electric vehicles, part i: recycling technology / A. Pražanová, V. Knap, and D.-I. Stroe // Energies, 2022, 15, 1086). Such solutions have low ionic conductivity, but sufficient to close the circuit with a chemical current source and slowly discharge it. At the same time, the process of electrolysis of the surrounding solution is carried out on the surface of the current source in the places of the current leads.

The disadvantage of these solutions is either the possibility of the release during electrolysis of gaseous or dissolved products that are not safe for the environment (sodium and potassium chlorides, sodium nitrate), or high cost (manganese and magnesium sulfates), or acceleration of corrosion processes with the battery case (sodium chlorides and potassium, ferrous sulfate).

Obtaining nickel(II) hydroxide for the positive electrode of an alkaline battery is carried out by precipitation from a solution of nickel salts (usually nickel sulfate) with a solution of sodium alkali when dispensing solutions, followed by washing, including with additives to the washing water of sodium carbonate, filtration and drying (RU2310951C1, 20.11 .2007). Used or defective nickel oxide lamellar electrodes subjected to deformation under pressure, screening and magnetic separation with subsequent dissolution in a sulfuric acid solution (RU2264000C1, 10.11.2005) can serve as raw materials. The resulting nickel(II) hydroxide is mixed with graphite, cobalt(II) hydroxide, barium sulfate, and this active mass is used to manufacture nickel oxide electrodes. Waste in such methods of obtaining nickel(II) hydroxide for the positive electrode of an alkaline battery is an aqueous solution of sodium sulfate with impurities of hydroxide and carbonate and traces of nickel. This solution is electrically conductive due to the presence of the appropriate ions.

The disadvantage of these inventions is that other types of waste are not considered, which may contain cobalt and nickel in an arbitrary ratio, including lithium-ion battery waste.

Disclosure of invention

The technical objective of the invention is to create a method that improves the efficiency and safety of processing lithium-ion batteries with the subsequent use of its products in the production of alkaline batteries.

The technical result consists in increasing the efficiency and safety of processing lithium-ion batteries with the subsequent use of its products in the production of alkaline batteries.

The technical result is achieved due to the fact that the method of processing lithium-ion batteries to obtain components of the positive electrode of alkaline batteries contains the following steps:

carrying out the discharge of spent lithium-ion batteries in a solution that is a waste in the production of nickel(II) hydroxide for the positive electrode of an alkaline battery;

discharged lithium-ion batteries are crushed and mechanically separated into several fractions that differ in particle size, density and chemical composition;

graphite powder and oxide powder containing oxides of cobalt, lithium, nickel, manganese, aluminum are obtained;

the resulting graphite powder is cleaned from traces of metals and used as an additive to the positive electrode of an alkaline battery;

the obtained powder of oxides of cobalt, lithium, nickel, manganese, aluminum is exposed to an aqueous solution of sulfuric acid, then precipitation and separation of a part of manganese in the form of manganese (IV) oxide, precipitation and separation of a mixture of hydroxides of nickel (II), cobalt (II), aluminum and manganese residue;

a mixture of nickel(II), cobalt(II), aluminum and manganese hydroxides is used as a nickel- and cobalt-containing mixed component of the positive electrode of an alkaline battery.

Implementation of the invention

For safe disposal of lithium-ion batteries, it is necessary to bring them to a guaranteed discharged state. To ensure the safety of the discharge, it is necessary to use available liquid electrolytes, the electrolysis of which will produce gaseous or dissolved products that are safe for the environment. To improve the efficiency of processing and production of electric batteries, it is necessary to provide for the use of lithium-ion battery processing products as raw materials in the production of alkaline batteries, reducing the number of stages if possible.

The discharge of spent lithium-ion batteries is carried out in a solution containing salts of sulfuric acid with impurities of hydroxides and carbonates, which is a waste in the production of nickel (II) hydroxide for the positive electrode of an alkaline battery, while the products of processing, namely graphite and a mixture of hydroxides that do not require separation nickel, cobalt, aluminum and manganese are used as positive electrode components for alkaline batteries.

When discharging power sources in a solution containing salts of sulfuric acid with impurities of hydroxides and carbonates, no gaseous or soluble products are released that are unsafe for the environment. The positive current leads of the current sources act as anodes and either water is oxidized with the release of gaseous oxygen (4OH ^- → O ₂ ↑ + 2H ₂ O + 4e ^- ), or the metal current collector is oxidized and dissolved (Fe → Fe ²⁺ + 2e ^- ). Negative current leads act as a cathode and either water is reduced with hydrogen evolution (2H ₂ O + 2e ^- → H ₂ ↑ + 2OH ^- ), or oxygen dissolved in water is reduced (O ₂ + 2H ₂ O + 4e ^- → 4OH ^- ) . Overheating of the solution due to exothermic processes is excluded by a large volume ratio of the solution to the accumulators. In order to prevent the concentration of hydrogen, it is sufficient to provide for natural ventilation or to provide aeration of the solution sufficient for the preferential flow of the process of reduction of dissolved oxygen. Nickel is also deposited on the negative current lead (Ni ²⁺ + 2e ^- → Ni), traces of which are present in the solution, which is a waste after obtaining nickel hydroxide, which contributes to its inclusion in further processing and purification of the sulfate solution from it.

Large batteries are disassembled in order to remove the batteries. Titanate and lithium iron phosphate batteries and accumulators are detected by preliminary sorting. It is advisable to process such batteries separately from other lithium-ion batteries, since lithium titanate will complicate further hydrometallurgical processing, and the presence of iron in the active mass of the positive electrode of an alkaline battery is undesirable. In the process of grinding discharged lithium-ion batteries and mechanical separation using successive crushers, conveyors, air filters and cyclones, they achieve separation into free-flowing particle concentrates that differ in density and size, as well as chemical composition: a light fraction of plastics that does not contain metal compounds; heavy plastic and structural metals; iron particles; copper foil particles; aluminum foil particles; graphite powder; powder containing oxides of cobalt, lithium, nickel, manganese, aluminum. Fractions of plastics, iron particles, copper particles, aluminum particles are transferred to interested consumers. Graphite powder is removed from traces of metals (for example, copper and/or other metals) by treatment with sulfuric acid, followed by filtration, and is used as an additive to the positive electrode of an alkaline battery. Powder of oxides of cobalt, lithium, nickel, manganese, aluminum is exposed to an aqueous solution of sulfuric acid. A significant proportion of manganese precipitates from an aqueous solution in the form of manganese (IV) oxide by adding hydrogen peroxide, aeration, and controlling the acidity of the medium by adding a solution of sodium hydroxide. The solution is then filtered. The manganese-containing cake is transferred to the interested consumer. The filtrate is used to precipitate a mixture of nickel(II), cobalt(II), aluminum and manganese hydroxides by adding sodium hydroxide solution, followed by separation by filtration, washing, re-filtration and drying operations. This mixture is used as a mixed nickel and cobalt containing component of the positive electrode of an alkaline battery. Aluminum and a moderate amount of manganese do not significantly affect the utilization of nickel in the positive electrode of an alkaline battery. Thus, complete separation of the mixture of nickel, cobalt, aluminum and manganese compounds is not required. This corresponds to the fact that no additional process steps are provided and that no additional reagents are consumed. The solution after separation of the mixture of nickel(II), cobalt(II), aluminum and manganese hydroxides contains sulfates, hydroxides and carbonates of sodium and lithium, aluminate ions, traces of fluoride ions, nickel, cobalt and manganese and can be transferred to an interested consumer for extraction lithium.

Example .

100 kg of spent intact lithium-ion batteries are kept for a day in a sodium sulfate solution with impurities of sodium hydroxide and sodium carbonate, which is a filtrate after separation of nickel(II) hydroxide in the production of a positive electrode material for a nickel-cadmium battery. For 1 kg of batteries there are 20 kg of solution. From the discharged batteries, 60 kg of lithium-ion batteries are separated, which are crushed and mechanically separated into several fractions that differ in particle size, density and chemical composition. Fractions of plastics, iron particles, copper foil particles, aluminum particles are transferred to interested consumers. Among the fractions there is a powder enriched with graphite (9 kg) and a powder enriched with cathode material (15 kg). Graphite enriched powder is stripped of traces of copper and other metals and used as an additive to the positive electrode of a nickel-cadmium battery. Using this graphite, 50-100 kg of positive electrode active mass is prepared, depending on the required graphite content. The cathode powder is dissolved in an excess of sulfuric acid, filtered, a 30% hydrogen peroxide solution is added to the heated filtrate while controlling the acidity of the medium and the temperature, and air is bubbled through it. Most of the manganese (at least 95%) in the form of oxide passes into the precipitate. Cake (4 kg) after filtration is considered as a manganese concentrate and is offered to interested consumers. To the filtrate after separating the manganese-containing cake under the control of the residual content and temperature, an alkali and carbonate solution is added to precipitate a mixture of nickel(II), cobalt(II), aluminum and manganese hydroxides. By repeated filtration, a cake (10 kg) is separated, containing 30% nickel, 30% cobalt, 5% aluminum, and 1% manganese. This cake after drying is used as an additive to the active mass of the positive electrode of the nickel-cadmium battery to ensure the required ratio of cobalt and nickel. Depending on the required cobalt content, 300-500 kg of the active mass of the positive electrode are prepared using a cake. The filtrate contains 1 kg of lithium in a liquid solution, also containing sodium sulfate with impurities of hydroxide and carbonate, can be transferred to an interested consumer for the extraction of lithium.

Claims (7)

A method for processing lithium-ion batteries to obtain components of a positive electrode of alkaline batteries, characterized in that it contains the following steps: carry out the discharge of spent lithium-ion batteries in a solution, which is a waste in the production of nickel (II) hydroxide for the positive electrode of an alkaline battery; discharged lithium-ion batteries are crushed and mechanically separated into several fractions that differ in particle size, density and chemical composition; graphite powder and oxide powder containing oxides of cobalt, lithium, nickel, manganese, aluminum are obtained; the resulting graphite powder is cleaned from traces of metals and used as an additive to the positive electrode of an alkaline battery; the obtained powder of oxides of cobalt, lithium, nickel, manganese, aluminum is exposed to an aqueous solution of sulfuric acid, then precipitation and separation of a part of manganese in the form of manganese (IV) oxide, precipitation and separation of a mixture of hydroxides of nickel (II), cobalt (II), aluminum and manganese residue; a mixture of nickel (II), cobalt (II), aluminum and manganese hydroxides is used as a nickel- and cobalt-containing mixed component of the positive electrode of an alkaline battery.