JP2005026088A - Processing method and recycling method of lithium battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of recycling and collecting valuable materials from a lithium battery. <P>SOLUTION: The processing method includes a process (step 245) of eluting lithium and a transit metal element from a material to be treated including a positive electrode activator separated from a metallic member by acid, and a process (step 247) of depositing hydroxide of transit metal or the like by mixing the obtained acidic solution and lithium hydroxide, a process (step 248) of separating the deposited material from the solution, a process (step 252) of depositing lithium carbonate by supplying carbon dioxide gas or the like to the solution after separation, and a process (step 254) of separating the deposited lithium carbonate from the solution. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【００８０】
この表１から判るように、実験例１〜３のいずれの条件（操作方法）によっても、ニッケル含有率が０．００２質量％以下という高純度の炭酸リチウムを回収することができた。また、ニッケル溶液と水酸化リチウム溶液とを酸化性条件下で混合した実験例２および実験例３では、このように高純度の炭酸リチウムが得られるとともに、反応液中のニッケル濃度が所定の許容量（ここでは２０ｍｇ／リットル）に至るまでに添加することのできるニッケルイオンの量が実験例１よりも多い。すなわち、水酸化リチウムの使用量（モル数）に対して処理し得るニッケル溶液（ニッケルイオン）の量が多い。このため、実験例２および実験例３では、同量の水酸化リチウムを用いて、実験例１よりも多くのニッケルを回収することができた。すなわち、水酸化リチウムの利用効率を高めることができた。
【００８１】
＜実施例６：遷移金属化合物析出工程の検討（３）＞
上述した実験例２の条件で、ニッケル溶液の添加量（ニッケル換算）と反応液のｐＨとの関係を調べた。また、実験例２の条件でニッケル溶液の添加量を異ならせて得られた各反応液から析出物を回収し、各回収物に含まれるニッケルの量（ニッケル回収量）を調べた。また、各反応液から析出物を分離した後の溶液（濾液）にＣＯ_２ガスを吹き込んで炭酸リチウムを析出させ、それらのニッケル含有率を測定した。以上の結果を表２および図１０に示す。
【００８２】
【表２】

【００８３】
表２および図１０に示すように、ニッケル溶液の添加量（ニッケル換算の添加モル数）が増すと反応液中のＬｉＯＨが消費されることによりｐＨが低下する。水酸化リチウムの使用量（ここでは２ｍｏｌ）に対するニッケル回収量は、ニッケルイオン添加量が増すにつれて増加する傾向にあるが、ｐＨが約８まで低下するとほぼ飽和する。また、濾液から得られる炭酸リチウムのニッケル含有率は、ｐＨ８までは０．００２質量％以下と少ないが、ｐＨ８を下回るとニッケル含有率が顕著に増加する。このことから、ニッケル回収量（水酸化リチウムの利用効率）と、濾液から得られる炭酸リチウムの純度とを両立させるためには、混合後の溶液のｐＨが凡そ８〜９．５となる量比でニッケル溶液（ニッケルイオン）と水酸化リチウムとを混合することが好ましい。
【００８４】
以上、本発明の具体例を詳細に説明したが、これらは例示にすぎず、特許請求の範囲を限定するものではない。特許請求の範囲に記載の技術には、以上に例示した具体例を様々に変形、変更したものが含まれる。
また、本明細書または図面に説明した技術要素は、単独であるいは各種の組み合わせによって技術的有用性を発揮するものであり、出願時請求項記載の組み合わせに限定されるものではない。また、本明細書または図面に例示した技術は複数目的を同時に達成するものであり、そのうちの一つの目的を達成すること自体で技術的有用性を持つものである。
【図面の簡単な説明】
【図１】実施例１においてリチウムイオン二次電池から有価物を回収する手順の概略を示すフローチャートである。
【図２】リチウムイオン二次電池の構成を模式的に示す断面図である。
【図３】リチウムイオン二次電池に用いられている正極シート（展開した状態）を示す平面図である。
【図４】揮発性成分の回収に用いる装置の概略構成例を示す模式図である。
【図５】炉内温度の推移を示す説明図である。
【図６】リチウム溶液からリチウム成分を回収する装置の概略構成例を示す模式図である。
【図７】リチウム溶液からリチウム成分を回収する手順の概略を示すフローチャートである。
【図８】実施例１で回収した有機溶媒のＧＣ−ＭＳ分析結果を示すチャートである。
【図９】ニッケル添加量と反応液のニッケルイオン濃度との関係を示す特性図である。
【図１０】ニッケル添加量と反応液のｐＨとの関係、および、ニッケル添加量と炭酸リチウムのニッケル含有量との関係を示す特性図である。
【符号の説明】
１：リチウムイオン二次電池（リチウム電池）
１０：電極体
１２２：正極集電体（金属部材）
１２４：正電極材層
１４２：負極集電体（金属部材）
１４４：負電極材層
１６：セパレータシート
２０：容器（金属部材）
３０：正極端子（金属部材）
４０：負極端子（金属部材）
６０：減圧加熱炉
６５：真空ポンプ
６７：一次冷却装置
７１：二次冷却装置
７２：排ガス浄化器
７４：コレクタ[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for recovering a valuable material from a lithium battery and a technique for using the recovered valuable material. In particular, the present invention relates to a method for obtaining a useful recovered material from a lithium-containing composite oxide used as a positive electrode active material, and a method for reusing (recycling) the recovered material as a component of a lithium battery.
[0002]
Various methods have been proposed for recovering valuable materials from waste lithium batteries. For example, in Patent Document 1, a battery cathode waste material containing a composite oxide of lithium and a transition metal element (such as lithium cobaltate) is dissolved in nitric acid, and this is filtered to contain lithium nitrate and a transition metal element nitrate. It is described that it is separated into a filtrate and a residue, and the transition metal hydroxide produced by adding lithium hydroxide to this filtrate is filtered off. Other prior art documents include Patent Documents 2 to 10.
[0003]
[Patent Document 1] JP-A-11-54159
[Patent Document 2] JP-A-10-255861
[Patent Document 3] JP-A-10-255862
[Patent Document 4] JP-A-11-6020
[Patent Document 5] Japanese Patent Laid-Open No. 2000-15216
[Patent Document 6] Japanese Patent Application Laid-Open No. 2003-27151
[Patent Document 7] US Pat. No. 5,888,463
[Patent Document 8] JP-A-8-41554
[Patent Document 9] JP-A-8-134556
[Patent Document 10] Japanese Patent Laid-Open No. 2000-119763
[0004]
However, the conventional methods still have room for improvement in terms of the usefulness (purity, properties, etc.) of the valuable materials to be recovered and the recovery costs. In particular, from a composite oxide containing lithium and a transition metal element used as a positive electrode active material of a lithium battery, the lithium component and the transition metal component can be more easily reused and / or more efficiently. It would be beneficial if it could be recovered.
[0005]
Accordingly, the present invention is a method for treating a lithium battery comprising a composite oxide containing lithium and one or more transition metal elements, and recovers valuable materials from the lithium battery in a form that is more easily reused. One object is to provide a processing method (a method for recovering valuable materials). Another object of the present invention is to provide a processing method for recovering such valuable materials more efficiently. Another object is to provide a method for recycling valuable materials recovered from lithium batteries. One related object is to provide a material for a lithium battery obtained by using valuable materials recovered from the lithium battery and a method for producing the same. Another related object is to provide a lithium battery using the lithium battery material and a method for producing the lithium battery.
[0006]
Means for Solving the Problem, Action and Effect One invention provided by this application is a positive electrode active material substantially composed of a composite oxide containing lithium and one or more transition metal elements. The present invention relates to a method of treating a lithium battery (typically a lithium ion secondary battery) comprising a substance. The method includes a step of eluting lithium and the transition metal element with an acid from a material to be treated that is separated from a metal member constituting the lithium battery and includes the positive electrode active material. Further, it includes a step of mixing the acidic solution obtained in the acid elution step and lithium hydroxide to precipitate the compound containing the transition metal element. A step of separating the precipitated transition metal compound from the solution can be included. Moreover, the process of supplying a carbon dioxide gas and / or carbonated water to the solution (lithium solution) after the isolation | separation and depositing lithium carbonate is included. A step of separating the precipitated lithium carbonate from the solution can be included. The transition metal compound that precipitates in the precipitation step may typically be primarily a hydroxide of the transition metal element. The transition metal hydroxide can be an oxyhydroxide depending on the metal species. For example, a typical example of the nickel compound precipitated in the precipitation step is nickel hydroxide (chemical formula: Ni (OH)₂And a compound represented by the chemical formula: NiOOH).
[0007]
Preferable examples of the complex oxide (hereinafter also referred to as “lithium / transition metal-containing complex oxide”) contained in the material to be treated include a complex oxide containing lithium and nickel. Here, “a composite oxide containing lithium and nickel” means an oxide containing lithium and nickel as constituent metal elements, and at least one other metal element other than lithium and nickel (that is, other than lithium and nickel) And a composite oxide containing a transition metal element and / or a typical metal element). Such composite oxides are, for example, of the general formula LiNi_1-xA_xO₂Can be expressed as A in this formula corresponds to the above “other at least one metal element”. Further, x in the formula is a value satisfying 0 ≦ x <0.5, preferably 0.1 <x <0.3. Other suitable examples of the composite oxide include composite oxides containing lithium and cobalt (including those containing at least one metal element other than lithium and cobalt), composite oxides containing lithium and manganese. (Including those containing at least one metal element other than lithium and manganese).
[0008]
According to the said processing method, a lithium component (lithium carbonate etc.) and a transition metal component (transition metal hydroxide etc.) can each be collect | recovered in a solid state from the to-be-processed material derived from a lithium battery. The lithium component and the transition metal component thus recovered as a solid are convenient for reuse.
In this treatment method, an acid elution step is performed on a material to be treated which is separated from metal battery components (battery container, current collector, etc.). Therefore, it is possible to prevent an excess metal element derived from the metal member from being mixed into the acidic solution obtained in the acid elution step. This is advantageous in that a highly useful (recyclable) recovery is obtained from the acidic solution.
[0009]
In a typical embodiment of this treatment method, an acidic solution obtained in the acid elution step and lithium hydroxide (LiOH) are mixed to precipitate a transition metal element hydroxide. In general, transition metal element hydroxides are substantially insoluble in water, and at least significantly less soluble than lithium hydroxide. For example, the solubility of LiOH in water at 25 ° C. is about 12.5 g / 100 g (H₂O), while Ni (OH)₂Solubility of about 7.5 × 10^-4g / 100 g (H₂O), the solubility of NiOOH is about 1 × 10^-4g / 100 g (H₂O), Fe (OH)₂Solubility of about 4.8 × 10^-3g / 100 g (H₂O), Cu (OH)₂Solubility of about 2.4 × 10^-3g / 100 g (H₂O), Co (OH)₂Solubility of about 8-22 × 10^-4g / 100 g (H₂O). By utilizing such a difference in solubility, the lithium component (lithium ion) and the transition metal component (deposited transition metal hydroxide) can be easily separated.
[0010]
In addition, lithium carbonate (Li) from the solution (lithium solution) after separating the transition metal compound (precipitate)₂CO₃) To precipitate carbon dioxide (CO₂) Or carbonated water (H₂CO₃) Is used. Thus, by depositing lithium carbonate using a material that does not contain an alkali metal component, lithium carbonate with less contamination of alkali metal elements other than lithium can be obtained. For example, sodium carbonate (Na₂CO₃) Can be significantly reduced in the amount of sodium component contained in the obtained lithium carbonate. Further, as described above, lithium hydroxide (LiOH) is used in the transition metal compound precipitation step. Thereby, the amount of sodium component contained in the obtained lithium carbonate is conspicuous compared with the case where other alkali metal hydroxide such as sodium hydroxide (NaOH) is used instead of lithium hydroxide in the precipitation step. Can be reduced. Although it is generally difficult to separate the sodium component once mixed from the lithium component, according to the method of the present invention, lithium carbonate having a high purity (especially, a small amount of alkali metal elements other than lithium mixed) can be obtained by a simple operation. Can be obtained.
[0011]
Many common lithium batteries include a positive electrode having a structure in which a positive electrode material containing a positive electrode active material is attached to a current collector (metal foil or the like) having good conductivity. This positive electrode material typically contains a binder (binder) such as polyvinylidene fluoride in addition to the positive electrode active material. Further, it may contain a conductive material such as carbon black. The positive electrode material containing these can be used as a material to be treated as it is (subject to an acid elution step). Alternatively, a positive electrode material from which at least a part (preferably substantially all) of the binder has been removed by a heat treatment or the like described below may be used as the material to be treated. In a lithium battery including a negative electrode having a configuration in which a negative electrode material including a negative electrode active material is attached to a current collector, a material to be processed including the negative electrode material and a positive electrode material (such as a positive electrode active material) is used. Alternatively, a material to be processed that contains substantially only a positive electrode material (such as a positive electrode active material) may be used.
[0012]
In a preferred embodiment of the treatment method provided by this application, a treatment for removing a volatile material by heating a lithium battery to be treated is performed. Here, the “volatile material” refers to a material that can be removed in a gaseous state (regardless of the type of evaporation, sublimation, thermal decomposition, etc.) by heating. Examples of such a volatile material include one or more of organic solvents, electrolytes (lithium salts, etc.), separators, binders, insulating materials, exterior paints, and the like that constitute the electrolytic solution. It is preferable to remove substantially all of the constituent materials, but the effects of the present invention can also be exhibited by removing at least a part of each constituent material. It is preferable to remove most of organic substances (organic solvent, separator, binder, etc.) contained in the lithium battery, and it is more preferable to remove substantially all. A part or all of the volatile material (typically organic matter) removed from the lithium battery by heating can be recovered and reused. An electrode material containing a positive electrode active material (a positive electrode material and a negative electrode material may be mixed) is separated from a battery component remaining after heating (for example, a metal material such as a battery container or a current collector), and the electrode The material is preferably subjected to the acid elution step as a material to be treated. The separation of the electrode material can be performed, for example, by sieving.
[0013]
The operation of heating the lithium battery to remove the volatile material (typically organic matter) is preferably performed by gradually increasing the heating temperature. More useful (reusable) recovery by recovering (separating) volatile materials removed in one or more stages separately from volatile materials removed in other stages You can get things.
In addition, it is preferable that the lithium battery to be processed is discharged almost completely in advance. As a result, at least one of the following effects can be obtained: improvement in handling and workability at the time of processing, improvement of working environment, downsizing and simplification of the processing apparatus.
[0014]
The step of precipitating the transition metal compound is preferably performed under the condition that the amount of lithium hydroxide is excessive with respect to the amount of transition metal ions contained in the acidic solution. Thereby, the density | concentration of the transition metal component (ion) remaining in the solution (lithium solution) after isolate | separating the deposited transition metal compound can be reduced. By reducing the concentration of transition metal ions remaining in the solution, the usefulness (purity) of lithium carbonate obtained from this solution can be increased.
[0015]
In another preferred embodiment of the treatment method provided by this application, the transition metal compound precipitation step is performed under oxidizing conditions. This promotes the formation and / or precipitation of transition metal compounds. For example, even if the amount of lithium hydroxide used is smaller than the amount of transition metal ions contained in the acidic solution (even if the excess degree is reduced), the concentration of transition metal ions remaining in the solution after separation Can be sufficiently reduced. Lithium hydroxide (unreacted material) surplus (used excessively) in this transition metal compound precipitation step is recovered as lithium carbonate in the subsequent lithium carbonate precipitation step together with lithium eluted from the material to be treated. Therefore, reducing the amount of lithium hydroxide used excessively with respect to the transition metal ion means that the utilization efficiency of lithium hydroxide (the transition metal contained in the acidic solution out of the lithium hydroxide mixed with the acidic solution) This is preferable in terms of increasing the ratio of lithium hydroxide that reacts with ions. One preferred embodiment of the transition metal compound precipitation step performed under oxidizing conditions includes a treatment of mixing the acidic solution containing hydrogen peroxide with lithium hydroxide. Another preferred embodiment includes a process of mixing the acidic solution and lithium hydroxide while supplying oxygen gas (typically bubbling).
[0016]
The treatment method provided by this application may further include a step of dissolving the transition metal compound separated in the separation step in an acid. Moreover, the 2nd precipitation process which adds a neutralizing agent to the acidic solution obtained at the acid dissolution process and precipitates the hydroxide of the said transition metal element can be included. By performing the acid dissolution step and the second precipitation step, a more useful recovered product (transition metal hydroxide) can be obtained. For example, for a lithium / transition metal composite oxide used as a positive electrode active material of a lithium battery in at least one of purity, metal composition, particle size, specific surface area and / or half width of X-ray diffraction peak, etc. It can be suitable as a raw material.
[0017]
The positive electrode active material contained in the material to be treated contains lithium, a first transition metal element, and at least one other metal element (hereinafter also referred to as “other metal element”). obtain. Preferable examples of the first transition metal element include Ni, Co, and Mn. The other metal element is a metal element different from the first transition metal element, and is Co, Al, Mn, Cr, Fe, V, Mg, Ti, Zr, Nb, Mo, W, Cu, Zn. , Ga, In, Sn, La and Ce may be one or more metal elements selected from the group consisting of. In such a case, in the acid elution step, lithium, the first metal element, and the other metal element are eluted into the acid, and the obtained acidic solution and lithium hydroxide are mixed to form the first transition metal element. A compound containing a compound (typically, a hydroxide of the first transition metal element) and the other metal element (typically a hydroxide of the other metal) may be precipitated. The precipitate may be separated from the solution and dissolved in the acid in the acid dissolution step. In the second precipitation step, a neutralizing agent is added to the solution obtained in the acid dissolution step, and the hydroxide of the other metal element is precipitated from the solution together with the hydroxide of the first transition metal element. It is good to let them.
[0018]
In this second precipitation step, the ratio of the content of the first transition metal element and the other metal element (typically a molar ratio or a mass ratio) is grasped for the solution obtained in the acid dissolution step. When the ratio is out of the predetermined range, after adjusting the quantitative ratio within the predetermined range, the hydroxide of the first transition metal element and the hydroxide of the other metal element are precipitated from the solution. (Preferably coprecipitation) is good. In particular, when the first transition metal element is nickel and the other metal element is cobalt, a state suitable as a raw material for a positive electrode active material is obtained by coprecipitation of nickel hydroxide and cobalt hydroxide. Thus, a recovered material in which nickel and cobalt are fused is obtained. In general, cobalt hydroxide precipitated from a solution tends to be colloidal, and can be easily separated from the liquid phase by coprecipitation with nickel hydroxide.
[0019]
Ammonia water is preferably used as the neutralizing agent. This aqueous ammonia may be used alone or in combination with other neutralizing agents (such as alkali metal hydroxides). When aqueous ammonia is used as the neutralizing agent, this second precipitation step involves the concentration of transition metal ions (in solutions containing the first transition metal element and other metal elements, the ions of the first transition metal element ( Concentration of the first transition metal ion), pH of the solution, ammonium ion (NH₄ ⁺) Is preferably performed while managing so that at least one of the items falls within a predetermined range. In the second precipitation step, it is preferable to manage such that two or more of these items are within a predetermined range, and it is particularly preferable to manage so that all three items are within the predetermined range. Thereby, a precipitate (mainly a transition metal element hydroxide) having at least one characteristic value in a desired range among the average particle diameter, the specific surface area, and the half width of the X-ray diffraction peak is obtained. It is preferable that two or more of these characteristic values are in a desired range, and it is particularly preferable that all three characteristic values are in a desired range. Such a precipitate is suitable as a raw material for producing a lithium / transition metal-containing composite oxide used as a positive electrode active material of a lithium battery. The average particle diameter can be measured by, for example, a particle diameter measuring apparatus using a laser diffraction / scattering method. The specific surface area can be measured by, for example, a specific surface area measuring apparatus using a BET method. The half width can be obtained from an X-ray diffraction intensity curve obtained using, for example, a general powder X-ray diffractometer.
[0020]
A preferred application of the treatment method provided by this application is a composite oxide in which the main (first) transition metal element of the lithium-transition metal-containing composite oxide is nickel (that is, a lithium-nickel-containing composite oxide). And a lithium battery comprising a positive electrode active material substantially composed of Further, this method is suitable as a method for treating such a positive electrode active material. Moreover, it is suitable as a method for treating the lithium / nickel-containing composite oxide. As a particularly preferred application object (treatment object), the first transition metal element is nickel, and a lithium / nickel-containing composite oxide containing cobalt as another metal element (subcomponent), substantially composed of this composite oxide And a lithium battery including such a positive electrode active material. The advantage of adopting the processing method of the present invention can be exhibited particularly well for such an application target. As an example of such a lithium-nickel composite oxide, a general formula LiNiO₂The thing represented by is mentioned. As another example, the general formula LiNi_1-xCo_xO₂The thing represented by is mentioned. Here, 0 <x <0.5, preferably 0.1 <x <0.3. A composite oxide containing Al, Mn, Cr, Fe or V instead of Co may be used. As yet another example, the general formula LiNi_1-yzCo_yAl_zO₂The thing represented by is mentioned. Here, 0 ≦ y <0.5 (preferably 0 <y <0.2), 0 <z <0.5 (preferably 0 <z <0.1), and 0 <(y + z ) <0.5 (preferably 0.1 <(y + z) <0.3). A kind selected from the group consisting of Mn, Cr, Fe, V, Mg, Ti, Zr, Nb, Mo, W, Cu, Zn, Ga, In, Sn, La, and Ce instead of or together with Al Alternatively, a composite oxide having two or more metal elements may be used.
[0021]
This application also provides a method for recycling (reusing) a lithium battery including a positive electrode active material substantially composed of a composite oxide containing lithium and one or more transition metal elements. For example, the present invention provides a method for recycling a component that can be a valuable component of such a lithium battery. In the recycling method, lithium hydroxide and transition metal hydroxide are mixed at a predetermined composition ratio. The mixture is fired to produce a lithium / transition metal-containing composite oxide. As at least one of lithium hydroxide and transition metal hydroxide used here, one obtained by any of the above-described treatment methods (that is, recovered from a lithium battery) is used. For example, lithium hydroxide produced by reacting with water after calcination of lithium carbonate obtained by any of the above-described treatment methods (that is, recovered from a lithium battery) is used as lithium hydroxide. Alternatively, as the transition metal hydroxide, a transition metal hydroxide obtained by any of the treatment methods described above (that is, recovered from a lithium battery) is used. This recycling method may include a step of attaching the obtained lithium / transition metal-containing composite oxide to a current collector to produce a positive electrode. A step of constructing a lithium battery by accommodating the positive electrode in a battery container together with the electrolytic solution and the negative electrode disposed via the electrolytic solution can be further provided.
[0022]
The techniques disclosed by this application include the following.
(1) A positive electrode active material substantially composed of a composite oxide containing lithium and one or more transition metal elements,
The composite oxide is obtained by firing a mixture in which lithium hydroxide and a hydroxide of the transition metal element are mixed at a predetermined ratio.
The following conditions:
As the lithium hydroxide, lithium hydroxide obtained by any of the above-described treatment methods (that is, recovered from a lithium battery) and then reacted with water after firing the lithium carbonate (for example, lithium hydroxide) Monohydrate (LiOH · H₂O)); and
As the hydroxide, a transition metal hydroxide obtained by any of the above-described processing methods (that is, recovered from a lithium battery) is used;
A positive electrode active material for a lithium battery (typically for a lithium ion secondary battery) characterized by satisfying at least one of the following.
[0023]
The lithium carbonate obtained by the above treatment method can have a high purity. In particular, the amount of alkali metal elements (such as sodium) other than lithium can be reduced. Therefore, lithium hydroxide obtained (prepared) from such lithium carbonate can be suitably used as a raw material for producing a positive electrode active material of a lithium battery. As the transition metal hydroxide, a transition metal hydroxide obtained by any of the methods described above (that is, recovered from a lithium battery) can be preferably used.
[0024]
(2) A lithium battery constructed using the positive electrode active material of (1) above. For example, a positive electrode in which a positive electrode material containing a positive electrode active material is provided on a positive electrode current collector,
A negative electrode in which a negative electrode material containing a negative electrode active material is provided on a negative electrode current collector;
An electrolyte solution disposed between the positive electrode material and the negative electrode material,
Here, the lithium battery is constructed by using (reusing) the positive electrode active material of the above (1) as the positive electrode active material.
[0025]
(3) A step of firing a mixture in which lithium hydroxide and one or more transition metal element hydroxides are mixed at a predetermined ratio to produce a composite oxide containing lithium and the transition metal element. When,
A step of attaching the composite oxide to a current collector to produce a positive electrode;
A lithium battery manufacturing method including a step of housing the positive electrode in a battery container together with an electrolytic solution and a negative electrode disposed through the electrolytic solution, and constructing a lithium battery,
The following conditions:
As the lithium hydroxide, lithium hydroxide produced by reacting with water after calcining lithium carbonate obtained by any of the above-described treatment methods (that is, recovered from the lithium battery) is used; and
As the transition metal hydroxide, a transition metal hydroxide obtained by any of the treatment methods described above (that is, recovered from a lithium battery) is used;
A method for producing a lithium battery, wherein at least one of the above is satisfied.
[0026]
DETAILED DESCRIPTION OF THE INVENTION The present invention can also be carried out in the following forms.
(Form 1)
In a treatment method including a step of removing a volatile material (mainly organic matter) by heating a lithium battery, the volatile material is removed under reduced pressure. In this case, a volatile material (such as an organic solvent) can be volatilized at a lower temperature than in the case of normal pressure using the boiling point drop due to reduced pressure. Thereby, for example, alteration (thermal decomposition etc.) of the organic solvent contained in the electrolytic solution can be suppressed, and a reusable recovered material can be obtained. In addition, since the volatilization rate can be increased by reducing the pressure, the time for heating is shortened, and the effect of obtaining a recovered material with less deterioration (good reusability) can be obtained. Thus, by heating under reduced pressure, the oxidation of the metal member which comprises a lithium battery can be suppressed. This is advantageous in collecting and reusing the metal member.
[0027]
(Form 2)
In the step of precipitating the transition metal hydroxide, the acidic solution and lithium hydroxide are mixed in an amount ratio such that the pH of the mixed solution is about 7.5 or higher, more preferably about pH 8 or higher. Thereby, the density | concentration of the transition metal component (ion) which remains in the solution after isolate | separating the deposited transition metal compound can be made low. Therefore, the recovery rate of the transition metal component from the acidic solution can be increased. Further, the purity of lithium carbonate obtained from the solution after separation of the transition metal compound can be increased (for example, the content of the transition metal component can be reduced). At least one of these effects can be realized. In the case where the precipitation step is performed under oxidizing conditions, it is particularly effective to perform the deposition step so as to satisfy such conditions. On the other hand, if the pH of the solution after mixing is too lower than the above range, the produced transition metal compound is likely to be dissolved in the solution and the amount of precipitation may be reduced. Further, from the viewpoint of reducing the amount of lithium hydroxide remaining in the solution after separation of the transition metal compound (increasing utilization efficiency of lithium hydroxide), the pH of the solution after mixing is about 7.5 to 10 (more preferably It is preferable to mix the acidic solution and lithium hydroxide in such a quantitative ratio that the pH is about 8 to 9.5).
[0028]
EXAMPLES Specific examples relating to the present invention will be described below, but the present invention is not intended to be limited to those shown in the examples. In addition, technical matters other than the contents specifically mentioned in the present specification and necessary for the implementation of the present invention can be understood as design matters for those skilled in the art based on the prior art. The present invention can be carried out based on the technical contents disclosed in the present specification and the common general technical knowledge in the field.
[0029]
<Example 1: Treatment method of lithium ion secondary battery>
First, the configuration of a lithium battery (herein, a used lithium ion secondary battery for a vehicle) processed in this embodiment will be described.
FIG. 2 is a schematic cross-sectional view showing the lithium ion secondary battery according to this example. As shown in this figure, the secondary battery 1 includes a wound electrode body 10 in which a pair of electrode sheets (a positive electrode sheet 12 and a negative electrode sheet 14) are wound in a flat shape via two separator sheets 16. And a flat rectangular parallelepiped (also referred to as square or flat) container 20 that accommodates the electrode body 10, and a positive electrode terminal 30 and a negative electrode terminal 40 that are connected to both axial ends of the electrode body 10.
[0030]
The state before winding of the positive electrode sheet 12 which comprises the electrode body 10 is shown in FIG. The positive electrode sheet 12 includes a long positive electrode current collector 122 and a positive electrode material layer 124 provided by adhering a positive electrode material in layers on both surfaces thereof. One long side (the upper side in FIG. 3) of the positive electrode sheet 12 serves as a connection portion 126 in which the positive electrode material layer 124 is not provided on any surface. In addition, since the structure of the negative electrode sheet 14 is the same as that of the positive electrode sheet 12, the number corresponding to the negative electrode sheet 14 is attached | subjected in the parenthesis of FIG. 3, and the overlapping description is abbreviate | omitted.
The electrode body 10 has a configuration in which these sheets are laminated in the order of the positive electrode sheet 12, the separator sheet 16, the negative electrode sheet 14, and the separator sheet 16, and the laminated body is wound in the longitudinal direction. Here, the positive electrode sheet 12 and the negative electrode sheet 14 are stacked such that the positions thereof are shifted from each other with respect to the winding axis direction, and the connection portions 126 and 146 protrude from both sides of the separator sheet 16. As a result, as schematically shown in FIG. 2, one end in the axial direction of the electrode body 10 is mainly composed of the positive electrode sheet 12, and the other end in the axial direction is mainly composed of the negative electrode sheet 14. A positive electrode terminal 30 and a negative electrode terminal 40 are connected to the one end and the other end, respectively.
[0031]
The positive electrode material layer 124 of the lithium ion secondary battery 1 is a positive electrode substantially composed of a lithium / nickel-containing composite oxide in which the first transition metal element is nickel and cobalt is contained as another metal element. The active material is the main component. Such a positive electrode active material has the general formula LiNi_1-xCo_xO₂(0 <x <0.5, preferably 0.1 <x <0.3). In the secondary battery 1 according to this example, the lithium-nickel-containing composite oxide (that is, LiNi) in which x in the general formula is about 0.2._0.8Co_0.2O₂Is used as a positive electrode active material. The positive electrode material layer 124 further contains carbon black (CB) and polytetrafluoroethylene (PTFE). The content ratio thereof is such that the mass ratio of positive electrode active material: CB: PTFE is approximately 85: 10: 5, for example. On the other hand, the negative electrode material layer 144 contains carbon black (CB) as a negative electrode active material as a main component and polytetrafluoroethylene (PTFE) as a binder. The content ratio thereof is such that the mass ratio of CB: PTFE is approximately 90:10, for example. The positive electrode current collector 122 and the positive electrode terminal 30 constituting the secondary battery 1 are made of aluminum (referring to aluminum or an aluminum alloy as a main constituent material; the same applies hereinafter), and the negative electrode current collector 142 and the negative electrode terminal. 40 is made of copper. The separator sheet 16 is a porous sheet made of polyolefin (here, made of polyethylene).
[0032]
The container 20 is made of aluminum and includes a bottomed cylindrical main body 22 and a lid body 24 that seals the upper end opening of the main body 22. The wound electrode body 10 is accommodated in the container 20. The positive electrode terminal 30 and the negative electrode terminal 40 extend through the lid body 24 to the outside of the container 20. These terminals 30 and 40 are fixed to the lid body by nuts 32 and 42. The positive terminal 30 and the lid 24 are separated by an insulator 26. The lid 24 is provided with a safety valve 28. The safety valve 28 is configured to automatically communicate the inside and outside of the container 20 to release the pressure when the internal pressure of the container 20 becomes higher than a predetermined set value.
[0033]
The electrode body 10 is impregnated with an electrolyte solution (not shown). As an organic solvent constituting this electrolytic solution, γ-butyrolactone, ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, 1,2-dimethoxyethane, 1,2-diethoxyethane, tetrahydrofuran, 1, One or two or more selected from the group consisting of 3-dioxolane and the like can be used. In the secondary battery 1 according to the present embodiment, a 7: 3 (mass ratio) mixed solvent of dimethyl carbonate (DMC) and ethyl methyl carbonate (EMC) is used. In addition, as an electrolyte constituting this electrolytic solution, LiPF₆, LiCF₃SO₃, LiC₄F₉SO₃, LiClO₄, LiBF₄, LiAsF₆, LiN (CF₃SO₂)₂, LiC (CF₃SO₂)₃1 type, or 2 or more types selected from various lithium salts, such as these, can be used. In the secondary battery 1 according to this example, lithium hexafluorophosphate (LiPF)₆) Is used. Its concentration is about 1 mol / liter.
[0034]
Next, a procedure for recovering valuable materials from the lithium ion secondary battery 1 having the above configuration will be described. FIG. 1 is a flowchart showing an outline of the procedure.
First, the used lithium ion secondary battery 1 is heated to recover volatile components (mainly organic substances) (step 220). This step 220 includes a step 222 for removing (collecting) the organic solvent, a step 224 for removing (collecting) the electrolyte, a step 226 for removing (collecting) the separator, and a step 228 for removing (collecting) the binder. Including.
[0035]
FIG. 4 schematically shows a schematic configuration example of an apparatus used for recovering such volatile components. In FIG. 4, the reduced pressure heating furnace 60 includes a main body 61 that partitions a processing chamber 64. An induction heating coil 62 is provided on the wall surface of the main body 61. The temperature in the processing chamber 64 can be controlled in an arbitrary pattern by a temperature controller 63 connected to the coil 62. A vacuum pump 65 is connected to the main body 61 so that the internal pressure of the processing chamber 64 can be arbitrarily controlled.
A primary cooling device 67 is provided below the processing chamber 64. The gas in the processing chamber 64 (for example, an organic solvent volatilized from the lithium ion secondary battery) is introduced into the primary cooling device 67 through the furnace gas conduit 66. An induction heating coil 68 is provided on the wall surface of the primary cooling device 67 so that the degree of cooling in the primary cooling device 67 can be adjusted. A secondary cooling device 71 is connected to the downstream of the primary cooling device 67 through an out-of-core gas conduit 70. The recovered material cooled and condensed (liquefied or solidified) by the secondary cooling device 71 is collected in the collector 74. The remaining gas is discharged outside through the exhaust gas purifier 72.
[0036]
Using the apparatus having such a configuration, for example, the organic solvent is volatilized and removed from the secondary battery 1 as described below, and the volatiles are recovered (step 222). That is, the used lithium ion secondary battery 1 opened in advance is accommodated in the processing chamber 64. The method for opening the secondary battery 1 may be appropriately selected from a method for opening a hole in a container, a method for operating a safety valve, and the like. The inside of the processing chamber 64 is depressurized by operating the vacuum pump 65. The degree of decompression is not particularly limited. Usually, it is appropriate to reduce the pressure to at least 80 kPa or less (typically 0.1 to 80 kPa). More preferably, the pressure is reduced to 50 kPa or less (typically 0.1 to 50 kPa). In the present embodiment, the inside of the processing chamber 64 is depressurized to 1 to 10 kPa.
While maintaining the reduced pressure state, the induction heating coil 62 is energized to increase the temperature in the processing chamber 64 (furnace temperature). Thereby, the secondary battery 1 is heated. The heating temperature at this time depends on the pressure in the processing chamber 64, and the boiling point of the organic solvent of the electrolytic solution used in the secondary battery 1 (if two or more organic solvents are included, Their azeotropic point can be near. Or it is also suitable to heat to the temperature which exceeds the boiling point of this organic solvent in the range which battery constituent materials other than the said organic solvent do not volatilize substantially. Thereby, the organic solvent can be efficiently volatilized from the secondary battery 1. Note that the boiling point of DMC at normal pressure is about 90 ° C., and the boiling point of EMC is about 107 ° C.
[0037]
In this embodiment, as shown in the temperature chart of FIG. 5, the furnace temperature is gradually raised from room temperature and maintained at about 85 ° C. for 30 minutes (the stage indicated by arrow a in the figure). Thereby, DMC volatilizes (gasifies) preferentially among the said organic solvents. The generated gas is introduced into the secondary cooling device 71 through the in-furnace gas conduit 66, the primary cooling device 67 and the out-furnace gas conduit 70. The secondary cooling device 71 cools the gas to condense (liquefy) the organic solvent and collect it in the collector 74. Next, the furnace temperature is further raised and maintained at 102 ° C. for 30 minutes (step indicated by arrow b in the figure). Thereby, the remaining organic solvent (mainly EMC) is volatilized (gasified), and liquefied and recovered by the secondary cooling device 71.
Thus, in this embodiment, an organic solvent (mixed solvent) containing two components having different boiling points is volatilized by two-stage heating. That is, most of the relatively low boiling point DMC is volatilized in the step a, and then the heating temperature is further increased to volatilize the remaining organic solvent (mainly EMC). In this way, by gradually changing the heating temperature and sequentially extracting from the low-boiling solvent to the high-boiling solvent, it is possible to efficiently volatilize and recover the organic solvent while suppressing alteration (decomposition, etc.) due to heating.
The vapor pressure of DMC at 24 ° C. is about 2.4 kPa, and the vapor pressure of EMC at 25 ° C. is about 3.3 kPa. For this reason, DMC and EMC volatilized in the ab steps are typically recovered as a mixed solvent. As will be described later, the recovered mixed solvent has a low content ratio of impurities (such as a thermal decomposition product of DMC and / or EMC) and has good reusability. For example, it can be used (reused) as an electrolytic solution for a lithium ion secondary battery.
[0038]
Next, from the battery constituent material remaining after the heating, an electrolyte (here, LiPF₆) Is removed by volatilization (mainly thermal decomposition), and the volatiles are recovered (step 224). For example, as in the temperature chart shown in FIG. 5, the furnace temperature is about 160 to 180 ° C. (LiPF₆(Corresponding to the thermal decomposition temperature range) (indicated by arrow c in the figure). This makes LiPF₆Is thermally decomposed into lithium fluoride (LiF) and phosphorus fluoride (PF)₅) Occurs. The phosphorus fluoride is introduced into the exhaust gas purifier 72 downstream of the vacuum pump 65 through the primary cooling device 67 and the secondary cooling device 71. A calcium hydroxide aqueous solution is stored in the exhaust gas purifier 72, and this calcium hydroxide reacts with phosphorus fluoride to produce calcium fluoride (CaF₂) And calcium phosphate (Ca₃(PO₄)₂) Is generated. Thereby, a fluorine component and a phosphorus component can be stably recovered (collected) as a solid. In addition, the heating temperature at the time of performing this step c is not limited to the above temperature, and may be a temperature range in which the electrolyte can be volatilized and removed from the secondary battery 1 at a practical rate. For example, it can be performed in a temperature range equal to or higher than the volatilization (thermal decomposition) temperature of the electrolyte. It is preferable to set the temperature within the range of volatilization (thermal decomposition) to + 50 ° C. If the degree of pressure reduction is approximately the same, the heating temperature in step c is preferably set to be 80 ° C. or higher than the temperatures in steps a and b.
[0039]
The separator is volatilized (mainly thermally decomposed) and removed from the battery constituent material remaining after the heating, and the volatiles are recovered (step 226). That is, as in the temperature chart shown in FIG. 5, the furnace temperature is maintained at about 300 ° C. (step shown by arrow d in the figure). Thereby, the separator 16 (porous polyethylene sheet) which comprises the electrode body 10 shown in FIG. 2 is thermally decomposed, and gas, such as a lower hydrocarbon, is produced. The gas can be recovered in the primary cooling device 67 and / or the secondary cooling device 71 as a liquid (for example, a viscous liquid mainly composed of a mixture of plural kinds of hydrocarbons) or as a solid. The obtained recovered material can be effectively reused as fuel or the like. In addition, the heating temperature at the time of performing step d is not limited to the above temperature, and may be a temperature range in which the separator can be volatilized (thermally decomposed) and removed from the secondary battery 1. If it is a separator made of polyolefin (made of polyethylene, polypropylene, etc.), the heating temperature can be set to a temperature range of 230 to 450 ° C., for example, and is preferably set to a range of 300 to 400 ° C. If the degree of reduced pressure is about the same, it is preferable to set the heating temperature in the d stage higher by 50 ° C. or more (typically 50 to 250 ° C., preferably 100 to 200 ° C.) than the temperature in the c stage.
[0040]
Further, the binder constituting the electrode material is removed by volatilization (mainly thermal decomposition) from the battery constituent material remaining after the heating, and the volatile matter is recovered (step 228). That is, as in the temperature chart shown in FIG. 5, the furnace temperature is maintained at about 550 ° C. (step shown by arrow e in the figure). Thereby, the binder (polytetrafluoroethylene) constituting the electrode material is thermally decomposed to generate gases such as lower hydrocarbons and fluorides. The generated gas can be recovered (collected) as a liquid or a solid at one or more of the primary cooling device 67, the secondary cooling device 71, and the exhaust gas purifier 72. In addition, the heating temperature at the time of performing this e step is not limited to the said temperature, What is necessary is just the temperature range which can volatilize a binder at a practical speed | rate and can remove from the inside of a furnace. For example, when polytetrafluoroethylene is used as the binder, the heating temperature in the step e can be set to a temperature range of 430 to 570 ° C. (preferably 500 to 550 ° C.). In the case where polyvinylidene fluoride is used as the binder, the heating temperature can be set to 400 to 570 ° C. (preferably 470 to 520 ° C.). If the degree of vacuum is about the same, it is preferable to set the heating temperature in step e above 50 ° C. (typically 50 to 350 ° C., preferably 100 to 300 ° C.) higher than the temperature in step d. From the viewpoint of shortening the time required for removing the binder and / or improving the removal rate of the binder, it is preferable to set the heating temperature at the time of performing the e step higher. However, the temperature should be such that the metal member constituting the battery (for example, an aluminum positive electrode current collector) does not melt (for example, about 570 ° C. or less, more preferably about 550 ° C. or less in the case of aluminum). preferable.
[0041]
In the above process (step 220), the heating temperature is raised in stages, and volatiles are recovered at each stage. In this way, by sequentially extracting the constituent materials from the secondary battery from a material having a low volatility temperature to a material having a high volatility, a reusable recovered material (valuable material) can be obtained. In addition, it is preferable to first extract (remove) the organic solvent from the battery in this way because the internal resistance of the battery is increased, and the handleability of the battery in subsequent steps is improved. Further, by removing the organic solvent (step 222) under reduced pressure, (1). Prevent deterioration of the organic solvent due to excessive heating, (2). Shortening the time required to remove the organic solvent, (3). At least one of the effects of saving energy for heating can be obtained.
[0042]
The battery constituent material (heating residue) from which the organic substances have been removed through the above-described process (Step 220) includes a container, positive and negative terminals, positive and negative current collectors, and positive and negative electrode materials ( (Excluding binders). In steps 232 and 234 shown in FIG. 1, the metal member is recovered (separated) from this heating residue.
That is, in step 232, the container 20 (see FIG. 2) is divided into upper and lower parts (cutting or the like), for example, and the electrode body 10 is taken out from the container 20. The nuts 32 and 42 are loosened to separate the container 20 (lid 22) from the electrode body 10. The container 20 (the main body 22 and the lid body 24) thus sorted can be reused for various purposes as an aluminum material.
[0043]
The wound electrode body 10 is in a state with many voids because the separator sheet 16 has already been lost (volatilized). For this reason, the positive electrode current collector 122 and the negative electrode current collector 142 constituting the electrode body 10 can be easily separated. For example, by pulling the positive electrode terminal 30 and the negative electrode terminal 40 away from each other in the winding axis direction of the electrode body 10, the negative electrode current collector that is also in the wound state from the positive electrode current collector 122 in the wound state. 142 can be withdrawn. In addition, the electrode material constituting the electrode material layers 124 and 144 on both surfaces of the current collectors 122 and 142 has already been volatilized from the current collector, and thus has fallen (peeled) from the current collector. Or at least it is in a state where it is easy to drop off. Therefore, the electrode material remaining on the surface of the current collector can be easily removed by a method of vibrating the current collector with a vibration sieve, a method of applying ultrasonic vibration by immersing the current collector in water, etc. . In this way, the current collector is separated and recovered (step 234). The collected current collector can be reused for various purposes as an aluminum material and a copper material.
[0044]
In step 245 shown in FIG. 1, the electrode material (mixture of positive electrode material and negative electrode material) separated from various battery constituent members by the above steps is used as the material to be processed, and the metal contained in the material to be processed. Elute the components with acid. Acids include hydrochloric acid (HCl) and sulfuric acid (H₂SO₄), Nitric acid (HNO₃) Etc. can be used. In this example, hydrochloric acid was used. The main metal elements eluted from the material to be treated by this acid elution step are lithium, nickel and cobalt constituting the positive electrode active material.
The acidic solution obtained in step 245 is filtered (step 246). This filtrate contains lithium ions, nickel ions and cobalt ions. On the other hand, the insoluble matter separated and recovered from the acidic solution by the filtration in Step 246 is mainly the carbon material (carbon black) used as the conductive material of the positive electrode material and the negative electrode active material. The recovered carbon material can be effectively used as, for example, a snow melting material, a soil improvement material, or the like.
[0045]
While stirring the hydrochloric acid solution (filtrate) obtained by filtration in step 246, a lithium hydroxide solution is added to this solution, and nickel ions and cobalt ions in the solution generate hydroxides (step 247). Here, the solubility of LiOH in water at 25 ° C. is about 12.5 g / 100 g (H₂O). In contrast, nickel hydroxide (Ni (OH)₂) Has a solubility of about 7.5 × 10 5 in water at 25 ° C.^-4g / 100 g (H₂O). Cobalt hydroxide (Co (OH)₂) Has a solubility of about 8-22 × 10 5 in water at 25 ° C.^-4g / 100 g (H₂O). Nickel hydroxide and cobalt hydroxide precipitate from the solution due to the significant difference in solubility. On the other hand, lithium ions and chlorine ions are present in the solution, but lithium chloride is usually not substantially precipitated because of its high solubility. Therefore, by filtering this solution (step 248), the deposited transition metal hydroxide (nickel hydroxide and cobalt hydroxide) and the solution containing lithium ions (lithium) can be separated.
[0046]
The lithium component is recovered as a solid from the lithium solution obtained in step 248 (steps 252 to 256). That is, carbon dioxide gas (CO₂), The lithium ions in the liquid₂Lithium carbonate (Li₂CO₃) Is generated (step 252). At this time, the lithium solution filtered off in step 248 may be concentrated and used within a range where lithium chloride (LiCl) does not precipitate. Lithium carbonate has a lower solubility in water than lithium chloride, and thus precipitates from the solution to form a precipitate. The precipitate is separated from the liquid phase (step 254) and dried (step 256). In this way, high purity lithium carbonate can be recovered. Note that the solution (filtrate) after separation of the precipitate in Step 254 can be reused as a hydrochloric acid solution used for eluting the metal component from the material to be treated in Step 245.
[0047]
As a method of supplying carbon dioxide gas to the lithium solution in this step 252, CO2 is added to the solution.₂A method of bubbling gas can be employed. Lithium solution (lithium ion) and CO₂In order to react more efficiently with CO₂The reaction is carried out under a pressurized atmosphere containing, for example, atmospheric pressure to about 1 MPa.₂A means such as spraying a lithium solution in an atmosphere containing can be appropriately employed. The carbon dioxide concentration in the atmosphere is preferably higher. For example, CO₂The reaction is preferably performed in an atmosphere having a concentration of about 50 to 100 vol% (more preferably about 80 to 100 vol%). Substantially CO₂It is particularly preferable to perform the reaction in an atmosphere composed of a gas. CO dissolved in the reaction solution₂As the concentration of increases, the solubility of lithium carbonate tends to increase. So, for example, CO₂Lithium ions and CO in an atmosphere of normal pressure or pressure (for example, normal pressure to about 1 Mpa or less) having a concentration of almost 100%₂And then dissolved in the reaction solution.₂The amount of CO2 from the liquid₂It is preferable to carry out the process. By this decarboxylation treatment,₂As the concentration decreases, the solubility of lithium carbonate decreases. As a result, a part of the lithium carbonate dissolved in the reaction solution before the decarboxylation treatment is precipitated (recrystallized), which can be easily separated and recovered from the liquid phase. The decarboxylation treatment is carried out by means such as stirring the reaction solution in an atmospheric atmosphere at normal pressure or reduced pressure, or bubbling air or an inert gas (such as nitrogen gas) into the reaction solution in the atmosphere. be able to. Further, the solubility of lithium carbonate tends to slightly decrease with increasing temperature (about 0.72 g / 100 g (H at 100 ° C.)).₂O)). Therefore, by increasing the temperature of the reaction solution (for example, heating to about 40 to 80 ° C.), the solubility of lithium carbonate can be reduced and the amount of precipitation can be increased. By such a technique, the recovery rate of the lithium component (lithium carbonate) from the lithium solution can be further improved.
The lithium carbonate thus obtained is a material (NaOH, Na) containing a different alkali metal element such as sodium in the recovery step.₂CO₃Etc.), the content of different kinds of alkali metal elements can be particularly small. Therefore, it can be suitably used (reused) for various purposes.
[0048]
The above-described process of recovering the solid lithium salt (lithium component) from the lithium solution obtained in step 248 can be performed using, for example, a recovery apparatus (manufacturing apparatus) having a configuration shown in FIG. The lithium component recovery apparatus 300 uses carbon dioxide gas (CO₂Gas)₂Contact part 320 and dissolved CO of the liquid to be treated₂CO to adjust the concentration₂A concentration adjusting unit 360 and a fluorine salt generating unit 380 that processes the liquid to be processed with fluorine ions are provided. Moreover, the 1st filtration apparatus 350 and the 2nd filtration apparatus 390 are provided as a separation means which isolate | separates solid (precipitate etc.) from a to-be-processed liquid.
[0049]
CO₂The contact unit 320 holds a raw material liquid storage tank 322 that receives and stores the filtrate (processed liquid (raw material liquid)) 321 obtained in step 248 from the pipe 323, and holds the processed liquid supplied from the raw material liquid tank 322. (Reserve) the first reaction tank (reaction chamber) 330 and the reaction tank 330 with CO₂CO supplying gas₂Gas supply means 333.
The raw material liquid tank 322 is connected to the reaction tank 330 via a pipe 324. The pipe 324 has a first liquid feeding device (pump) 325. A sprayer 326 as spraying means (spray supply means) is provided at the tip of the pipe 324. By operating the pump 325, the liquid to be treated (raw material liquid) in the raw material liquid tank 322 can be sprayed (sprayed in a mist) from the sprayer 326 into the reaction tank 330. The reaction tank 330 includes a liquid level detector 327 that detects the amount of liquid to be processed in the reaction tank 330. The liquid level detector 327 is electrically connected to the pump 325. Thereby, for example, when the liquid level of the liquid to be processed in the first reaction tank 330 reaches a predetermined height, a liquid level detection signal is sent from the liquid level detector 327 to the pump 325 to stop the operation of the pump 325, The supply (spraying) of the liquid to be treated to the reaction tank 330 can be stopped.
[0050]
CO₂The gas supply means 333 is provided with CO (not shown).₂CO from source₂Gas (in this example, substantially CO₂A gas consisting of ) Into the reaction vessel 330₂A gas supply pipe 333a is provided. A fine bubbler 333b is provided at the tip of the supply pipe 333a, and the CO₂The gas can be supplied into the liquid to be treated as fine bubbles (fine bubbles). FIG. 6 shows one CO.₂The gas supply means 333 (one supply pipe 333a and one fine bubbler 333b) is shown, but two or more COs for one reaction vessel 330 are shown.₂A gas supply means 333 may be provided. Further, a CO having a configuration in which two or more fine bubblers 333b are provided in one supply pipe 333a.₂The gas supply means 333 may be used.
The reaction tank 330 pumps up the liquid to be processed accumulated therein, and is a space (typically CO 2) above the liquid level of the liquid to be processed in the reaction tank 330.₂A circulation spray device (a spray circulation means) 336 for spraying on a gas-filled gas phase) is provided. The circulation spray device 336 includes a pipe 336 a disposed so that one end is located below the liquid level detector 327 and the other end is located above the liquid level detector 327. The pipe 336a includes a pump 336b. A sprayer 336c is provided at the other end of the pipe 336a. Although FIG. 6 shows one circulation spray device 336, two or more circulation spray devices 336 may be provided for one reaction tank 330.
[0051]
The reaction tank 330 includes a temperature detector (thermometer) 331. A steam passage 332 is formed on the outer periphery of the reaction tank 330. Steam can be supplied to the steam passage 332 to adjust the temperature of the reaction vessel 330. In addition, the reaction tank 330 includes a pressure detector 334 and a pressure adjustment valve 335. The pressure in the reaction tank 330 can be adjusted by opening and closing the pressure adjustment valve 335 as necessary. The reaction tank 330 includes a pH measuring device 337 that measures the pH of the liquid to be treated inside. The progress of the reaction can be grasped by the pH of the liquid to be treated. The liquid to be treated collected in the reaction tank 330 can be stirred by the stirrer 338.
[0052]
One end of a pipe 341 is connected to the bottom of the first reaction tank 330. The other end of the pipe 341 is connected to the filtration container 352 of the first filtration device 350. Further, the pipe 341 is provided with a cock 341 and a second liquid feeding device (pump) 343. The liquid to be processed in the reaction tank 330 can be transferred to the filtration container 352 through the pipe 341.
The filtration container 352 is divided into upper and lower parts by a filter 353 disposed on the filter plate. The pipe 341 is connected to an inlet chamber 352 a formed above the filter 353. By passing (filtering) the liquid to be processed from the inlet chamber 352a to the outlet chamber 352b below the filter, solids such as precipitates can be separated (collected) from the liquid to be processed. A gas supply pipe 354 is connected to the inlet chamber 352a. A gas (typically air) can be supplied from the gas supply pipe 354 to increase the pressure in the inlet chamber 352a (pressurize the liquid to be treated introduced into the inlet chamber 352a). By making the pressure of the inlet chamber 352a (back pressure of the liquid to be processed) relatively higher than that of the outlet chamber 352b, the filtration speed of the liquid to be processed can be improved. An exhaust pipe 355 is connected to the outlet chamber 352b so that excess gas pressure can be released.
[0053]
One end of a pipe 356 and a pipe 371 is connected to the outlet chamber 352b of the filtration container 352 at the bottom. The other end of the pipe 356 is CO₂The concentration adjusting unit 360 is connected to the recrystallization tank 362. The other end of the pipe 371 is connected to a second reaction tank 382 of a fluorine salt generation unit 380 described later. A pipe 356 leading to the recrystallization tank 362 is provided with a cock 357, and a pipe 371 reaching the second reaction tank 282 is provided with a cock 372 and a fourth liquid feeding device (pump) 373. By opening and closing these cocks 357 and 372, the liquid to be processed that has passed through the filter 353 can be selectively transferred to any tank of the recrystallization tank 362 and the second reaction tank 382.
[0054]
The recrystallization tank 362 is made of CO.₂As the concentration adjusting means, an atmosphere adjusting mechanism for adjusting the atmosphere in the recrystallization tank 362 is provided. For example, as shown in FIG. 6, the atmosphere adjusting mechanism substantially includes CO in the recrystallization tank 362.₂Non-CO to supply gas (eg air) that does not contain₂A configuration including a gas supply pipe 363 and an exhaust pipe 364 for allowing excess gas to escape to the outside of the recrystallization tank 362 can be employed. In addition, a configuration in which the recrystallization tank 362 is open to the atmosphere is one aspect of the atmosphere adjustment mechanism. The liquid to be processed held in the recrystallization tank 362 can be stirred by the stirrer 365. Further, the temperature of the recrystallization tank 362 can be adjusted by a temperature adjusting mechanism (not shown).
The liquid to be treated in the recrystallization tank 362 can be transferred to the inlet chamber 352a of the filtration container 352 through a pipe 366 having a third liquid feeding device (pump) 367. By passing through the filter 353 of the filtration container 352, solids (precipitates and the like) can be separated from the liquid to be processed that has passed through the recrystallization tank 362. As described above, the first filtration device 350 has the CO 2₂The liquid to be processed transferred from the contact part 320 (first reaction tank 330), and CO₂Both of the liquids to be processed transferred from the concentration adjusting unit 360 (recrystallization tank 362) can be filtered. Moreover, it is comprised so that a to-be-processed liquid can be circulated between the recrystallization tank 362 and the 1st filtration apparatus 350 (filtration container 352).
[0055]
The fluorine salt generation unit 380 has a second reaction tank 382 to which the other end of the pipe 371 is connected. The liquid to be processed that has passed through the filter 353 of the first filtration device 350 can be transferred from the outlet chamber 352 b of the filtration container 352 to the second reaction tank 382 via the pipe 371. Further, the fluorine salt generation unit 380 has a hydrofluoric acid storage tank 383. Fluorine ions (hydrofluoric acid in this embodiment) can be supplied from the hydrofluoric acid storage tank 383 to the second reaction tank 382 through the fluorine supply pipe 384. The second reaction tank 382 includes a fluorine ion concentration measuring device 385 that measures the fluorine ion concentration of the liquid to be treated. Moreover, the stirrer 386 which stirs the to-be-processed liquid in a tank is provided.
[0056]
One end of a pipe 387 is connected to the second reaction tank 382. The pipe 387 has a fifth liquid feeding device (pump) 388, and the other end is connected to the filtration container 392 of the second filtration device 390. The filtration container 392 is divided up and down by a filter 393 provided on the filter plate, and a pipe 387 is connected to an inlet chamber 392a above the filter. By passing (filtering) the liquid to be processed from the inlet chamber 392a to the outlet chamber 392b below the filter, solids such as precipitates can be separated (collected) from the liquid to be processed. A gas supply pipe 394 is connected to the inlet chamber 392a, and an exhaust pipe 395 is connected to the outlet chamber 382b. By supplying gas (typically air) from the gas supply pipe 394 and making the pressure in the inlet chamber 392a (back pressure of the liquid to be processed) relatively higher than that in the outlet chamber 392b, the filtration rate can be improved. it can. A filtrate discharge pipe 396 is connected to the outlet chamber 392b. The liquid to be treated that has passed through the filter 393 can be taken out (discharged) from the system by opening the cock 397 of the filtrate discharge pipe 396.
[0057]
With reference to the flowchart shown in FIG. 7, an example of a method for producing a lithium salt (recovering a lithium component) from the filtrate (raw material solution) obtained in step 248 using the lithium salt production apparatus 300 having such a configuration. explain.
First, in the first reaction tank 330, the liquid to be treated and CO₂CO in contact with gas₂A contact process (step 252) is performed. This CO₂The contacting step is preferably performed at a pressure in the reaction vessel 330 of about 100 to 1000 kPa (more preferably about 100 to 200 kPa). Here, the pressure in the reaction vessel 330 was set to 150 kPa. In addition, the space above the liquid to be treated in the reaction tank 330 (the gas phase in contact with the liquid surface of the liquid to be treated) is charged with CO.₂A gas mainly composed of (for example, CO₂A gas having a concentration of about 50-100 vol%, more preferably about 80-100 vol%. Here CO₂Gas with a concentration of almost 100%), that is, the space is CO₂CO is formed while the packed bed 330a is formed.₂It is preferable to perform a contact process. Such pressurized CO₂The atmosphere is, for example, CO₂This can be realized by using the gas supply means 333 and the pressure adjustment valve 335. Further, the temperature in the reaction vessel 330 may be adjusted to about 30 to 100 ° C. (preferably about 40 to 80 ° C.) by means such as circulating steam in the steam passage 332. Here, the temperature was about 60 ° C.
[0058]
While stirring the liquid to be treated in the reaction vessel 330 with the stirrer 338, the CO₂CO 2 from the fine bubble device 333b of the gas supply means 333₂Supply (bubble) gas bubbles. Unreacted CO₂The gas rises to the liquid level of the liquid to be treated and₂It merges with the packed bed 330a or dissolves in the liquid to be treated. Here, the liquid to be treated and CO₂In order to lengthen the contact time with the gas bubbles, CO 2 is arranged so that the fine bubbler 333 b is located near the bottom surface of the reaction vessel 330.₂The gas supply means 333 is preferably configured. CO₂By supplying gas as fine bubbles as possible, CO₂The contact area between the gas and the liquid to be processed is increased. CO₂The time for the gas bubbles to float in the liquid to be treated (the time for contact with the liquid to be treated) becomes longer. In this way, the liquid to be treated and CO₂Increasing the contact area with the gas and / or increasing the contact time can be achieved by treating the liquid to be treated and CO.₂It is effective to increase the reaction efficiency with.
[0059]
This CO₂In the contacting step, the pump 336b of the circulation spray device 336 is operated to pump up the liquid to be treated that has accumulated in the reaction tank 230, and CO 2₂Spraying (jetting in a mist) may be performed in the gas filling layer 330a. The liquid to be treated (droplet) sprayed is CO₂CO constituting the gas packed bed 330a₂It falls in the reaction tank 330 while being in contact with the gas. In this way, the liquid to be treated and CO2 are circulated by spraying and circulating the liquid to be treated inside the reaction tank 330.₂The contact efficiency (reaction efficiency) with can be further increased. When supplying the liquid to be treated (raw material liquid) from the raw material liquid storage tank 322 to the reaction tank 330 (step 251), the pressurized CO₂The liquid to be treated may be sprayed from the sprayer 326 into the reaction tank 330 adjusted to the atmosphere. As a result, the liquid to be treated and CO₂Can be further increased.
[0060]
Liquid to be treated and CO₂As the reaction proceeds with the amount of the reaction product exceeding the solubility in the liquid to be treated, the product (mainly lithium carbonate) precipitates from the liquid to be treated. Further, as the reaction proceeds, the pH of the liquid to be treated gradually decreases. By detecting this pH change with the pH measuring device 337, the degree of progress of the reaction can be grasped. CO₂The contacting step is preferably performed until the pH of the liquid to be treated falls to a range of about 9 to 7 (preferably about pH 8 to 7). If the pH is too low, the solubility of lithium carbonate tends to increase.
As described above, CO in the liquid to be treated₂Gas bubbling and CO₂By performing the process of spraying the liquid to be processed in the packed bed 330a, the liquid to be processed and CO₂Can be reacted efficiently. Thereby, for example, even when the degree of pressurization in the reaction vessel 330 is relatively low (for example, about 100 to 200 kPa), it is possible to achieve practically preferable reaction efficiency. The fact that the degree of pressurization can be reduced is preferable from the viewpoint of miniaturization and / or weight reduction of the apparatus.
[0061]
CO₂The liquid to be treated that has undergone the contact process is transferred from the reaction vessel 330 to the first filtration device 350. That is, the cock 342 of the pipe 341 is opened, the pump 343 is operated, and the contents (processed liquid) of the reaction tank 330 are extracted. This liquid to be treated is introduced into the inlet chamber 352a of the filtration container 352 and filtered through the filter 353 (step 254a). By this separation step, precipitates (mainly lithium carbonate) contained in the liquid to be treated are separated on the filter 353. The liquid to be processed (filtrate) that has passed through the filter 353 accumulates in the outlet chamber 352b. If necessary, the filtration speed can be increased by sending pressurized air or the like from the gas supply pipe 354 to the inlet chamber 352a.
[0062]
Next, the cock 357 of the pipe 356 is opened, and the liquid to be processed in the outlet chamber 352 b is transferred to the recrystallization tank 362. This recrystallization tank 362 is open to the atmosphere, and the atmosphere (non-CO 2) is stirred while the liquid to be treated is stirred by the stirrer 365.₂Dissolved CO in contact with the atmosphere)₂The density can be reduced (step 255). This CO₂The solubility of lithium carbonate in the liquid to be treated is reduced by the concentration reduction step, and lithium carbonate dissolved in the liquid to be treated before the step can be newly precipitated (recrystallized). Note that the solubility of lithium carbonate tends to decrease slightly with increasing temperature (for example, about 1 g / 100 g (H at 60 ° C.)₂O), but at 100 ° C., about 0.72 g / 100 g (H₂O)). Therefore, by increasing the temperature of the liquid to be treated by a temperature adjustment mechanism (not shown) or the like (for example, heating to about 40 to 80 ° C.), the solubility of lithium carbonate is reduced and the precipitation amount (yield) is further increased. it can.
[0063]
CO₂The liquid to be processed that has undergone the concentration reduction process is transferred from the recrystallization tank 362 to the first filtration device 350. That is, the pump 367 provided in the pipe 366 is operated to introduce the contents (liquid to be processed) of the recrystallization tank 362 into the inlet chamber 352a of the filtration container 352. The liquid to be treated is filtered through a filter 353 to separate precipitates (mainly lithium carbonate) (step 254b).
[0064]
In addition, the CO₂The to-be-processed liquid which passed through the density | concentration reduction process and the isolation | separation process is used for a fluorine salt production | generation process. That is, the cock 372 of the pipe 371 is opened, the pump 373 is operated, and the liquid to be processed in the outlet chamber 352b is transferred to the second reaction tank 382. While stirring the liquid to be treated in the second reaction tank 382, hydrofluoric acid is added from the hydrofluoric acid storage tank 383 through the hydrofluoric acid supply pipe 384. This hydrofluoric acid (fluorine ion) reacts with lithium carbonate remaining (dissolved) in the liquid to be treated and / or unreacted lithium ions and the like to generate a fluoride salt (mainly lithium fluoride). Lithium fluoride has a lower solubility than lithium carbonate (eg, about 0.13 g / 100 g (H₂O)), lithium fluoride and the like can be precipitated from the liquid to be treated as the reaction proceeds. The precipitate (mainly lithium fluoride) can be separated from the liquid to be treated by transferring the liquid to be treated to the filtration container 392 of the second filtration device 390 and filtering it with the filter 393 (step 258).
[0065]
Most of the lithium component is removed from the liquid to be treated (filtrate) that has passed through the filter 393. This filtrate is discharged from the discharge pipe 396 of the outlet chamber 392b. In addition, the said fluorine salt production | generation process is good to implement by adjusting the supply amount of a hydrofluoric acid (fluorine ion) so that the density | concentration of the fluorine ion contained in the to-be-processed liquid after this process completion may not exceed 15 ppm. This facilitates disposal of the filtrate discharged after filtration (step 258). For example, when the fluorine ion concentration detected by the fluorine ion concentration measuring device 385 reaches 1 to 3 ppm, the supply of hydrofluoric acid is stopped, and the fluorine ions in the liquid to be treated are consumed by the progress of the reaction and the fluorine ion concentration is lowered. Furthermore, an operation method such as adding hydrofluoric acid can be employed. As a configuration of the apparatus suitable for performing such an operation, a liquid supply device (pump) (not shown) is provided in the fluorine supply pipe 384, and a fluorine ion concentration measuring device 385 is electrically connected to the pump. Can be adopted.
[0066]
In steps 260 to 274 shown in FIG. 1, a positive electrode active material in which cobalt is added to a lithium-nickel composite oxide using the transition metal hydroxide (precipitate) separated (recovered) from the solution in step 248 (typically In particular, LiNi_1-xCo_xO₂A transition metal hydroxide material useful as a raw material for producing (a positive electrode active material represented by 0 <x <0.5, preferably 0.1 <x <0.3) is synthesized. Here, LiNi_0.8Co_0.2O₂The case of synthesizing (preparing) a raw material for producing the positive electrode active material represented by
[0067]
The transition metal hydroxide (precipitate) separated in step 248 is dissolved in an acid (step 260). As the acid, hydrochloric acid, sulfuric acid, nitric acid and the like can be used. In this example, sulfuric acid was used. The concentration of nickel ions and cobalt ions contained in this sulfuric acid solution is measured by a conventional method. And when the ratio of the concentration (content) of these ions deviates from a preset target value (here, the molar ratio of Ni: Co in terms of metal is 0.8: 0.2) or more. Replenish the missing ionic species from outside (add to solution). Thus, the amount ratio of both ions contained in the sulfuric acid solution is adjusted to be within a predetermined range (step 266). Since only the shortage is compensated for in this way, the amount of the transition metal component (for example, cobalt) to be newly used can be saved. If the amount ratio of nickel ions and cobalt ions contained in the sulfuric acid solution obtained in step 260 can be predicted (understood) from previous processing experience and preliminary experiments, an operation for measuring the concentration of these ions is performed. Can be omitted.
[0068]
A neutralizing agent is added to a sulfuric acid solution containing nickel ions and cobalt ions in a predetermined quantitative ratio (step 270). In this embodiment, ammonia water (NH₄OH) and sodium hydroxide (NaOH) were used. The addition of the neutralizing agent maintains the concentration of nickel ions in the solution in the range of 50 to 500 ppm, maintains the pH of the solution in the range of 8 to 13, and the concentration of ammonium ions in the range of 5 to 15 g / liter. It was carried out while maintaining the control. At this time, nickel hydroxide having a relatively large amount of precipitation was smoothly precipitated (co-precipitated) while taking in cobalt hydroxide. This precipitate is a fusion of nickel and cobalt in a state suitable as a raw material for a lithium / transition metal-containing composite oxide for a positive electrode active material. The resulting precipitate was recovered from the solution by filtration or the like (step 272) and dried (step 274). The average particle size of the transition metal hydroxide material thus obtained was in the range of 3 to 20 μm. The specific surface area is 3-20m²/ G. The half width of the X-ray diffraction peak was in the range of 0.2 to 14 deg. A positive electrode active material produced using such a transition metal hydroxide material can constitute a lithium ion secondary battery excellent in battery performance (for example, discharge capacity).
[0069]
<Example 2: Production of positive electrode active material using recovered material>
The transition metal hydroxide material obtained in Example 1 is suitable as a raw material for producing a positive electrode active material because nickel and cobalt are mixed (fused) in an appropriate state. For example, this transition metal hydroxide material and lithium hydroxide material (LiOH.H₂O, etc.) are mixed at a predetermined ratio and fired under appropriate conditions, whereby a positive electrode active material (for example, LiNi) which is a lithium / nickel-containing composite oxide and is substantially composed of a composite oxide containing cobalt._0.8Co_0.2O₂Can be obtained. Here, the lithium hydroxide material used together with the transition metal hydroxide material can be prepared using the lithium carbonate recovered in Example 1 above. That is, when the recovered lithium carbonate is baked at high temperature, Li carbonate is removed by decarboxylation₂O is generated. This Li₂Lithium hydroxide (monohydrate) obtained by reacting O with water can be used for the production of the positive electrode active material.
[0070]
A production example of a lithium ion secondary battery using (reusing) the positive electrode active material produced in this example will be briefly described. For example, in order to manufacture the lithium ion secondary battery 1 having the configuration shown in FIG. 2, the positive electrode active material is dispersed in a suitable solvent together with carbon black (CB) and polytetrafluoroethylene (PTFE) powder to form a positive electrode material. Prepare paste. As the solvent, water, N-methylpyrrolidone, or the like can be used. This paste is applied to a positive electrode current collector (aluminum foil or the like) to volatilize the solvent. In this way, a positive electrode sheet in which a positive electrode material layer is provided on both surfaces of the positive electrode current collector is produced. The positive electrode material paste can be applied using a comma coater, a die coater, or the like. On the other hand, carbon black (CB) and polytetrafluoroethylene (PTFE) powder are dispersed in a suitable solvent to prepare a negative electrode material paste. This is applied to a negative electrode current collector (copper foil or the like) and the solvent is volatilized to produce a negative electrode sheet in which negative electrode material layers are provided on both sides of the negative electrode current collector. These electrode sheets are laminated via a separator sheet (porous polyethylene sheet or the like). The laminate is wound to produce an electrode body. A positive electrode terminal and a negative electrode terminal are connected to both ends in the axial direction of the electrode body by welding or the like. This is housed in a battery container made of aluminum or the like together with the electrolytic solution. As an electrolytic solution, about 1 mol / liter of LiPF in a 7: 3 (mass ratio) mixed solvent of dimethyl carbonate (DMC) and ethyl methyl carbonate (EMC).₆A material in which is dissolved can be used. As this DMC-EMC mixed solvent, the one recovered in Step 222 of Example 1 can be used. In this way, a lithium ion secondary battery can be constructed (regenerated).
[0071]
<Example 3: Evaluation of recovered material>
By heating the lithium ion secondary battery under reduced pressure as in Example 1, it is possible to obtain a more useful recovered product (mixed solvent) while preventing alteration of the organic solvent and the like. Further, the recovery efficiency (volatilization rate) can be increased.
FIG. 8 is a chart showing the results of GC-MS analysis (gas chromatograph mass spectrometry) of the organic solvent recovered in the collector 74 in Step 222 of Example 1 (stage a to stage b in FIG. 5). From this result, the peak marked with “* 1” can be identified as DMC having a molecular weight of about 90, and the peak marked with “* 2” can be identified as EMC having a molecular weight of about 104. When the concentration of each component was calculated from the intensity of each peak and a concentration calibration curve, the composition of the recovered organic solvent was almost the same as the composition of the original electrolytic solution. Further, no peaks other than those corresponding to DMC and EMC appear in FIG. Therefore, the ratio of components other than DMC and EMC (decomposed products thereof) contained in the recovered product is considered to be about 1 to 2% at most. This indicates that the recovered material obtained has good reusability.
[0072]
<Example 4: Study of transition metal compound precipitation step (1)>
A process (corresponding to step 247 in FIG. 1) in which an acidic solution containing transition metal ions and an aqueous lithium hydroxide solution are mixed to precipitate a hydroxide of a transition metal element was studied.
[0073]
(Experimental example 1)
2 liters of a 1 mol / liter LiOH aqueous solution (pH 12 or more) was prepared, and this was heated to 60 to 90 ° C. (preferably 75 to 85 ° C.) in a reaction vessel. In addition, nickel chloride containing 1 mol of nickel (NiCl₂) A solution was prepared. While stirring the lithium solution in the reaction vessel, NiCl₂The solution was added slowly. As a result, nickel ions react with LiOH to precipitate nickel hydroxide. The produced lithium chloride is dissolved in the reaction solution. At this time, when the nickel ion concentration (mg / liter) of the reaction solution was measured, as shown in FIG. 9, the nickel ions were not contained in the reaction solution until the addition amount of the nickel solution reached about 0.8 mol (in nickel conversion). Not detected. This is presumably because the reaction proceeds smoothly because the LiOH concentration in the reaction solution is relatively high, and the nickel ions added to the reaction vessel are quickly consumed from the reaction solution. When the addition amount of the nickel solution exceeded about 0.8 mol (in terms of nickel), nickel ions were detected in the reaction solution, and thereafter, the nickel ion concentration increased as the addition amount of the nickel solution increased. For example, when the allowable value of nickel ion concentration is 20 mg / liter, as shown in FIG. 9, the amount of nickel solution added up to this allowable value was about 0.9 mol in terms of nickel.
[0074]
(Experimental example 2)
Experimental Example 2 is an example in which the above precipitation process was performed under oxidizing conditions. The operation until the nickel solution corresponding to 0.5 mol in terms of nickel was added to the lithium hydroxide solution was performed in the same manner as in Experimental Example 1. The subsequent nickel solution was added while bubbling oxygen gas into the reaction solution. The bubbling amount (supply amount) of oxygen gas was 200 to 500 ml / min. When the nickel ion concentration of the reaction solution was measured, as shown in FIG. 9, in the present experimental example, no nickel ions were detected until the amount of nickel solution added reached about 0.88 mol (in nickel conversion). When this addition amount is exceeded, nickel ions are detected, but compared with Experimental Example 1, the concentration of nickel ions relative to the addition amount was low overall. The amount of the nickel solution added up to the allowable value (20 mg / liter) was about 0.96 mol / liter in terms of nickel.
[0075]
(Experimental example 3)
Experimental Example 3 is another example in which the above precipitation process was performed under oxidizing conditions. That is, a hydrogen peroxide-containing nickel solution prepared by mixing a hydrogen peroxide solution with a nickel solution was added to the lithium hydroxide solution in the same manner as in Experimental Example 1. When the nickel ion concentration of the reaction solution was measured, as shown in FIG. 9, in this experimental example, no nickel ions were detected until the amount of nickel solution added reached about 0.86 mol (in nickel conversion). When this addition amount is exceeded, nickel ions are detected, but compared with Experimental Example 1, the concentration of nickel ions relative to the addition amount was low overall. The amount of the nickel solution added up to the allowable value (20 mg / liter) was about 0.95 mol / liter in terms of nickel.
[0076]
(Experimental example 4)
Regarding the mixing of the nickel solution and the lithium hydroxide solution under oxidizing conditions, the following experiment was further conducted. That is, a nickel sulfate solution (pH about 4) containing 5 g of nickel per liter was prepared (nickel concentration: 5 g / liter). To 250 ml of this nickel sulfate solution, 100 ml of 10% hydrogen peroxide water was added to prepare a hydrogen peroxide-containing nickel solution. Moreover, the lithium hydroxide solution (pH 12 or more) containing 1 mol / liter LiOH was prepared. When 42.6 ml of this lithium hydroxide solution was placed in a beaker and the hydrogen peroxide-containing nickel solution was gradually added dropwise with stirring, Ni (OH) was added almost simultaneously with the addition.₂Crystal was precipitated (generated). Compared with the case where the above experiment was performed in the same manner except that a nickel solution not mixed with hydrogen peroxide was used, the precipitation of crystals was relatively accelerated in this experimental example. Also, oxygen gas bubbles were generated by mixing the hydrogen peroxide in the hydrogen peroxide-containing nickel solution with an alkaline solution. When the reaction system was visually observed, the deposited Ni (OH)₂Was observed to turn dark green. This phenomenon is caused by Ni (OH)₂It is inferred that this was caused by oxidation of nickel oxyhydroxide (NiOOH). When the dropwise addition of the hydrogen peroxide-containing nickel solution was continued, the amount of precipitated crystals gradually increased, but no new precipitation was observed when the pH of the reaction solution was below about 7.
[0077]
<Example 5: Study of transition metal compound precipitation step (2)>
Under the conditions of Experimental Example 1, the nickel solution (NiCl containing 1 mol of nickel) until the nickel ion concentration of the reaction solution reached 20 mg / liter.₂Solution) was added. That is, an amount of nickel solution corresponding to about 0.9 mol in terms of nickel was added to a solution containing 2 mol of lithium hydroxide. The reaction solution was filtered to separate precipitates from the solution and dried. As a result of analysis, the amount of nickel contained in the collected precipitate (the amount of nickel obtained using 2 mol of lithium hydroxide) was about 0.9 mol. In the solution (filtrate) after separating the precipitate from the reaction solution, an amount corresponding to 10% (0.2 mol) of LiOH put in the reaction vessel remains (dissolved) unreacted. This filtrate contains CO₂Gas was blown to precipitate lithium carbonate, which was separated from the solution and dried. As a result of the analysis, the nickel content of the obtained lithium carbonate was about 0.0018% by mass.
[0078]
Similarly, the nickel solution was added under the conditions of Experimental Examples 2 and 3 until the nickel ion concentration in the reaction solution reached 20 mg / liter, respectively. That is, in Experimental Example 2, about 0.96 mol in terms of nickel, and in Experimental Example 3, an amount of nickel solution corresponding to about 0.95 mol in terms of nickel was added. When the precipitate collected from this reaction solution was analyzed, the precipitate obtained under the conditions of Experimental Example 2 contained about 0.96 mol, and the precipitate obtained under the conditions of Experimental Example 3 contained about 0.95 mol of nickel. It was out. Further, in the solution (filtrate) after separation of the precipitate, about 0.08 mol of LiOH remains in Experimental Example 2 and about 0.10 mol of LiOH remains unreacted in Experimental Example 3. These filtrates contain CO₂The nickel content of lithium carbonate obtained by blowing gas was about 0.0016% by mass in Experimental Example 2 and about 0.0015% by mass in Experimental Example 3.
The above results are summarized in Table 1.
[0079]
[Table 1]

[0080]
As can be seen from Table 1, high-purity lithium carbonate having a nickel content of 0.002% by mass or less could be recovered under any of the conditions (operation methods) in Experimental Examples 1 to 3. In Experimental Example 2 and Experimental Example 3 in which a nickel solution and a lithium hydroxide solution are mixed under oxidizing conditions, high-purity lithium carbonate is obtained in this way, and the nickel concentration in the reaction solution is a predetermined level. The amount of nickel ions that can be added up to the capacity (here 20 mg / liter) is larger than that in Experimental Example 1. That is, the amount of nickel solution (nickel ions) that can be treated is large with respect to the amount of lithium hydroxide used (number of moles). For this reason, in Experimental Example 2 and Experimental Example 3, more nickel than in Experimental Example 1 could be recovered using the same amount of lithium hydroxide. That is, the utilization efficiency of lithium hydroxide was able to be improved.
[0081]
<Example 6: Study of transition metal compound precipitation step (3)>
Under the conditions of Experimental Example 2 described above, the relationship between the amount of nickel solution added (in nickel) and the pH of the reaction solution was examined. In addition, precipitates were collected from each reaction solution obtained by varying the amount of nickel solution added under the conditions of Experimental Example 2, and the amount of nickel contained in each collected product (nickel recovery amount) was examined. In addition, the solution (filtrate) after separating the precipitate from each reaction solution is added to the CO 2 solution.₂Gas was blown to deposit lithium carbonate and their nickel content was measured. The above results are shown in Table 2 and FIG.
[0082]
[Table 2]

[0083]
As shown in Table 2 and FIG. 10, when the amount of nickel solution added (the number of moles added in terms of nickel) increases, the pH decreases due to consumption of LiOH in the reaction solution. The amount of nickel recovered relative to the amount of lithium hydroxide used (here 2 mol) tends to increase as the amount of nickel ion added increases, but is almost saturated when the pH is lowered to about 8. The nickel content of lithium carbonate obtained from the filtrate is as low as 0.002% by mass or less up to pH 8, but the nickel content increases remarkably when the pH is below 8. From this, in order to achieve both the nickel recovery amount (utilization efficiency of lithium hydroxide) and the purity of the lithium carbonate obtained from the filtrate, the ratio by which the pH of the mixed solution becomes approximately 8 to 9.5. It is preferable to mix a nickel solution (nickel ion) and lithium hydroxide.
[0084]
Specific examples of the present invention have been described in detail above, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above.
In addition, the technical elements described in the present specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology illustrated in the present specification or the drawings achieves a plurality of objects at the same time, and has technical utility by achieving one of the objects.
[Brief description of the drawings]
1 is a flowchart showing an outline of a procedure for recovering valuable materials from a lithium ion secondary battery in Example 1. FIG.
FIG. 2 is a cross-sectional view schematically showing a configuration of a lithium ion secondary battery.
FIG. 3 is a plan view showing a positive electrode sheet (expanded state) used in a lithium ion secondary battery.
FIG. 4 is a schematic diagram illustrating a schematic configuration example of an apparatus used for recovery of a volatile component.
FIG. 5 is an explanatory diagram showing a transition of the furnace temperature.
FIG. 6 is a schematic diagram showing a schematic configuration example of an apparatus for recovering a lithium component from a lithium solution.
FIG. 7 is a flowchart showing an outline of a procedure for recovering a lithium component from a lithium solution.
8 is a chart showing GC-MS analysis results of the organic solvent recovered in Example 1. FIG.
FIG. 9 is a characteristic diagram showing the relationship between the amount of nickel added and the nickel ion concentration in the reaction solution.
FIG. 10 is a characteristic diagram showing the relationship between the amount of nickel added and the pH of the reaction solution, and the relationship between the amount of nickel added and the nickel content of lithium carbonate.
[Explanation of symbols]
1: Lithium ion secondary battery (lithium battery)
10: Electrode body
122: Positive electrode current collector (metal member)
124: Positive electrode material layer
142: Negative electrode current collector (metal member)
144: Negative electrode material layer
16: Separator sheet
20: Container (metal member)
30: Positive terminal (metal member)
40: Negative electrode terminal (metal member)
60: Reduced pressure heating furnace
65: Vacuum pump
67: Primary cooling device
71: Secondary cooling device
72: Exhaust gas purifier
74: Collector

Claims (12)

A method of treating a lithium battery comprising a positive electrode active material substantially composed of a composite oxide containing lithium and one or more transition metal elements,
Elution of lithium and the transition metal element with an acid from the material to be treated that is separated from the metal member constituting the lithium battery, and the cathode active material;
Mixing the acidic solution obtained in the acid elution step and lithium hydroxide to precipitate the compound containing the transition metal element;
Separating the precipitated transition metal compound from the solution;
Supplying carbon dioxide gas and / or carbonated water to the separated solution to precipitate lithium carbonate;
Separating the precipitated lithium carbonate from the solution. The method according to claim 1, wherein the lithium battery is heated to remove organic substances, an electrode material containing a positive electrode active material is separated from battery constituent members remaining after the heating, and the electrode material is used as the material to be treated. . The method according to claim 2, wherein the organic substance is removed by gradually increasing the heating temperature of the lithium battery. The method according to any one of claims 1 to 3, wherein the transition metal compound precipitation step is performed under oxidizing conditions. The method according to claim 4, wherein the transition metal compound precipitation step includes a treatment of mixing the acidic solution containing hydrogen peroxide with a lithium hydroxide solution. Dissolving the transition metal compound separated in the separation step in an acid;
6. The method further comprises a second precipitation step of adding a neutralizing agent to the acidic solution obtained in the acid dissolution step to precipitate a hydroxide of the transition metal element. The method described in 1. The positive electrode active material includes lithium, a first transition metal element, and at least one other metal element,
In the acid elution step, lithium, the first transition metal element and the other metal element are eluted in an acid,
In the precipitation step, the compound containing the first transition metal element and the compound containing the other metal element are precipitated,
In the acid dissolution step, the first transition metal compound and the other metal element compound separated in the separation step are dissolved in an acid,
The method according to claim 6, wherein in the second precipitation step, a hydroxide of the first transition metal element and a hydroxide of the other metal element are precipitated. For the solution obtained in the acid dissolving step, grasp the ratio of the content of the first transition metal element and the other metal element, and if the ratio is out of the predetermined range, the ratio is within the predetermined range. The method according to claim 7, wherein after the adjustment, the hydroxide of the other transition metal element is precipitated from the solution together with the hydroxide of the first transition metal element. The neutralizer includes aqueous ammonia,
In the second precipitation step, the concentration of transition metal ions, the pH of the solution, and the concentration of ammonium ions are all controlled within a predetermined range.
The method according to any one of claims 6 to 8, wherein the method is performed so as to obtain a precipitate in which an average particle diameter, a specific surface area, and a half width of an X-ray diffraction peak are each in a desired range. The method according to any one of claims 1 to 9, wherein a main transition metal element of the positive electrode active material is nickel. The method according to claim 1, wherein the positive electrode active material includes cobalt. Firing a mixture of lithium hydroxide and one or more transition metal element hydroxides in a predetermined ratio to produce a composite oxide containing lithium and the transition metal element;
A step of attaching the composite oxide to a current collector to produce a positive electrode;
Including a positive electrode in a battery container together with an electrolytic solution and a negative electrode disposed via the electrolytic solution, and constructing a lithium battery,
The following conditions:
As the lithium hydroxide, lithium hydroxide produced by reacting with water after calcination of the lithium carbonate obtained by any one of claims 1 to 5; and
The transition metal hydroxide obtained by the method according to any one of claims 6 to 9 is used as the transition metal hydroxide;
The lithium battery recycling method characterized by satisfy | filling at least one of these.

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