WO2008022415A1

WO2008022415A1 - Process for the extraction of lithium compounds found in secondary lithium-ion batteries

Info

Publication number: WO2008022415A1
Application number: PCT/BR2007/000034
Authority: WO
Inventors: Marcelo Bozzo; Maria Do Rosário Fabeni HURTADO; Maria Angela Brotto Baldini Lance
Original assignee: Lg Eletronics De São Paulo Ltda
Priority date: 2006-08-21
Filing date: 2007-02-08
Publication date: 2008-02-28
Also published as: BRPI0603719A

Abstract

To proceed with the separation of lithium compounds, this process starts with the extraction of lithium from electrodes and separators by immersing them into a mixture of commercial ethanol and acetone at 5%. Preferably, after two hours the extraction will be completed, the electrodes, separators, nickel contacts, aluminum contacts and plastic tapes are removed and they are used subsequently for recycling and the solution is filtered in order to obtain the lithium compound, which is then dried and weighed. The filtrate, besides the lithium compounds, the alcohol solution, acetone, solvent residues, battery electrolytes are obtained. Apart from that, the filtrate obtained from filtering (alcohol, acetone and batteries electrolyte residues) is distilled, obtaining alcohol at 960GL that can be used again in the extraction process of lithium compounds.

Description

PROCESS FOR THE EXTRACTION OF LITHIUM COMPOUNDS FOUND IN SECONDARY LITHIUM-ION BATTERIES

The present invention refers to a process that allows the separation of lithium compounds found in lithium-ion batteries at the end of their lifespan.

The worldwide reserves of lithium, in contained lithium oxide, are estimated to be around 9.54 million tons. Bolivia with 56.6%, Chile with

314%, and the USA with 4.3% are among the countries with most lithium reserves. The Brazilian lithium reserves are located in the state of Minas Gerais and the state of Ceara.

The growing worldwide demand for lithium-ion batteries has resulted in a reduction regarding minerals containing lithium which has led to the reuse of lithium in batteries, therefore minimizing the environmentar impact.

Besides the decrease of lithium in the earth crust, batteries that are not disposed of correctly may result in their compounds being carried away by rivers, rain, wintl, and other ways thus contaminating soil and water.

Excess of fϊthϊum in the organism affects the central nervous system, causing blurred vision, hearing disorder (noise), dizziness, feebleness, and shivering.

The lithium batteries do not contain toxic metals, however, they are likely to burn if the metallic lithium is exposed to humidity while the cells are in the process of corrosion. In order to be appropriately discarded, the batteries should be completely discharged so that all the metallic lithium is cleared. Almost all fϊthϊum systems contain inflammable and toxic electrolyte..

The scientific literature describes a method to recover the lithium compounds by using ethyl acetate as a solvent. The materials from electrodes and separators are grinded and placed in ethyl acetate during five hours, the negative electrode material is separated mechanically and the negative electrode and the separators are placed again in ethyl acetate in order to extract the active materia!. This material is dried, grinded and sifted, and fϊnaffy submitted to treatment under high temperature. The results of X-ray diffraction show that fϊthium nickelate was recovered.

Another patented process is related to recovering lithium present in batteries and in other scrap. The lithium battery is placed in liquid nitrogen in order to reduce the lithium reactivity and then it is cut in small pieces which are in turn immersed in a fϊfhium hydroxide solution. According to the authors, the pH should be close to ten in order to avoid the formation of H2S which is highly toxic. A variety of lithium compounds are formed during the reaction, depending on the other compounds present in scrap, which sporadically precipitate on the basic solution.

Another method describes the extraction of lithium from the separators, collectors, and materials from the positive efectrode. These sofid materials are immersed in water so that the lithium present in these materiafs reacts with wafer to form lithium hydroxide. After evaporation, lithium hydroxide reacts with hydrochloric acid and then, it is heated, dried and dehydrated in order to obtain anhydrous lithium chloride, which is melted and efectrolyzed to regenerate lithium.

The literature also describes a method to recover the lithium compounds from the cell components. The components of the cell that contain lithium are immersed in water so that lithium hydroxide could be formed. Alcohol is added to the aqueous solution so that the lithium hydroxide precipitation can occur.

Another method described in the literature identifies the procedure to recover lithium cobaltate. At first, the battery is cut mechanically or by using laser, the electrolyte is recovered in acetronitrila. Solid materiafs can be separated according to their density or magnetic properties. The filtrate obtained in the separation is transferred to electrolytic cell. During the electrolysis, the lithium cobalt oxide is reduced to cobalt oxide and the lithium moves from the electrode to the solution. The lithium hydroxide solution is decanted and the cobalt oxide is washed and stored. in spite of their efficiency, the conventional methods for recovering lithium compounds from secondary lithium batteries require a high amount of energy. Different from other methods, this takes six to ten times the amount of energy in order to recover metals from recycled batteries.

Another disadvantage regarding convenfroπaf methods for recovering lithium compounds from secondary lithium batteries is the fact that they require the use of heating.

Another disadvantage regarding the conventional methods for recovering lithium compounds from secondary lithium batteries is the fact that liquid nitrogen is used for cooling, and consequently increases the process cost.

Another disadvantage regarding conventional methods for recovering lithium compounds from secondary lithium batteries is the fact that when the battery is grinded and the lithium is dissolved, the traditional chemical precipitation methods are used, which are fess selective in some cases.

According to what was exposed in this work, the objective of this invention is to describe a simple method involving a few stages, economically feasible, efficient, and at a low energy consumption to separate the lithium compounds present in lithium batteries.

Another objective regarding this invention is to provide a process to extract chemical compounds found in secondary lithium batteries with reactions that occur at room temperature. The objectives stated previously will be achieved through the process of extracting lithium compounds from separators and electrodes. This process starts ater the batteries are opened. The invention will be described in the only figure attached to this document, which represents the flowchart regarding the extraction of lithium compounds found in secondary lithium batteries.

In the extraction stage of the lithium compounds (2), the compounds are extracted from the separators and the electrodes by immersing them into a mixture of commercial ethanol and acetone at 5% preferably with a proportion of 70OmLJIO batteries. After approximately two hours the extraction is completed, the electrodes and separators are removed and the solution is fiftered in order to obtain the fithium compound, which is dried and weighed, obtaining a mass of 5g/10 batteries. The filtrate holds the alcohol/acetone solution and residues of solvent and battery electrolyte. At this stage, besides obtaining the lithium compounds, the separators, nickel contacts, aluminum contacts and plastic tapes are separated manually and the positive and negative electrodes are used in the forthcoming stages. The hydrated ethanof prevents the lithium to react violently.

As this reaction occurs in a soft way, there is no need for cooling during the reaction as there is no explosion risk. Thus, the process becomes more simple and economically feasible.

The presence of acetone in the solution causes the dissolution of the compounds to be more efficient, the amount of acetone suggested in the mixture is within a range between f 5 and 5%. However, \t is suggested to use only 5% of acetone for maximum efficiency.

The equations next show how the dissolution of lithium compounds and the subsequent formation of oxide and lfthium carbonite occur. The formation of lithium hydroxide and lithium carbonate, originated from salt used to prepare the electrolyte, as well as the active material from electrodes, occurs from the following reactions: 1) solubilization of fithium compounds In ethanol, forming lithium ethoxide and hydrogen-ion and reactions of lithium ethoxide with water:

C₂H₅OH + Li⁺ -→ C₂H₅OLi + H+

C₂H₅OLi + H₂O — » C₂H₅OH + LiOH 2) Reaction of lithium-ion with water:

Li⁺ + H₂O → LiOH + H⁺

3) Reaction of lithium carbide from positive electrode with water:

LiC₆ + H₂O → HC₆ + LiOH 4) Reaction of lithium carbonate formation:

2LiOH + H₂CO₃ → Li₂CO₃ + 2H₂O

The filtrate obtained from filtering (alcohol, acetone and batteries electrolyte residues) is distilled, obtaining alcohof at 96⁰GL that can be used again in the extraction process of lithium compounds. When the battery is grinded and the lithium dissolved, the traditional chemical precipitation methods can be used. The disadvantage is that they are less selective in some cases.

Besides the economical aspects regarding the recovery and reuse of materials described previously, this invention also contributes to the conservation and preservation of the environment.

Although a preferable solution has been described and illustrated, it rs important to stress that other solutions can be performed within the same scope.

Claims

1 - PROCESS FOR THE EXTRACTION OF LITHIUM-ION COMPOUNDS FOUND IN SECONDARY LITHIUM-ION BATTERIES Characterized by the fact that, for the extraction of lithium compounds (2), lithium is extracted from electrodes and separators by immersing them into a mixture of commercial ethanol and acetone at 5%. After two hours the extraction will be compfeted, the electrodes, separators, nickef contacts, aluminum contacts and plastic tapes are removed and they are used subsequently for recycling. The solution will go through a filtering process to obtain lithium compounds, which are dried and weighed. The filtrate, besides the lithium compounds, the alcohol solution, acetone, solvent residues, battery electrolytes are obtained. Apart from that, the filtrate obtained from filtering (alcohol, acetone and batteries electrolyte residues) is distϊffed, obtaining alcohol at 96⁰GL that can be used again in the extraction process of lithium compounds.