JP2000095525A - Production of lithium/nickel-containing compound - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a lithium/nickel-containing compound as the active material of a positive electrode for a high quality nonaqueous electrolyte cell in an easy and effective manner by allowing lithium to react with nickel oxyhydroxide (derivative) in an organic solvent. SOLUTION: Lithium or a lithium compound having reducing power to nickel oxyhydroxide (derivative) is allowed to react with a lithium compound having relatively weak reducing power and nickel oxyhydroxide (derivative) in an organic solvent. In other way, a lithium compound having no reducing power or relatively weak reducing power to nickel oxyhydroxide (derivative) is allowed to react with nickel oxyhydroxide (derivative) in the presence of a material having reducing power to nickel oxyhydroxide (derivative) in an organic solvent. The material having reducing power to nickel oxyhydroxide (derivative) is, e.g. an organic compound such as an alcohol.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a lithium nickel-containing compound and a high capacity nonaqueous electrolyte battery using the same as a positive electrode active material.

[0002]

2. Description of the Related Art In recent years, with the development of portable electronic devices, development of high-performance batteries has been desired. Lithium ion batteries using a carbon material for the negative electrode and lithium cobalt oxide, which is a composite oxide having a layered structure for the positive electrode, have been put into practical use as nonaqueous electrolyte batteries having a high operating voltage and a high energy density. However, since lithium cobaltate is scarce and expensive as a resource, a lithium-containing manganese composite oxide or lithium nickelate has been proposed as a substitute. These composite oxides are positive electrode active materials for a so-called 4V lithium secondary battery having an average operating voltage of about 4V.

[0003] On the other hand, from the viewpoint of the development of ICs operating at a low voltage of 3 V or less and the viewpoint of battery safety, it is estimated that the demand for 3 V non-aqueous electrolyte secondary batteries will increase in the future. . However, only LiMnO ₂ or V ₂ O ₅ is generally known as a positive electrode active material for a 3V-based non-aqueous electrolyte secondary battery. Even with these materials, there are problems in terms of discharge capacity and cycle life characteristics. Since it has many points, it is currently used only for very limited uses such as for memory backup.

On the other hand, it has recently been reported that nickel oxyhydroxide can be used as a positive electrode active material for a 3V-based non-aqueous electrolyte secondary battery (The 64th Annual Meeting of the Electrochemical Society, lecture number 3A06). According to this report, while the theoretical discharge capacity of nickel oxyhydroxide is about 290 mAh / g, it corresponds to a utilization rate of 95% or more of 285 mAh.
It shows an initial discharge capacity as high as / g, and it can be said that it can be sufficiently used for applications requiring high energy density batteries, such as power supplies for notebook computers. However, since this nickel oxyhydroxide is in a charged state as a positive electrode active material, a battery cannot be produced by directly combining with a negative electrode active material in a discharged state such as graphite.

[0005] Therefore, it is essential to use either a charged negative electrode active material such as graphite, lithium metal or lithium alloy containing lithium or to prepare a discharged positive electrode active material. From the viewpoints of safety and stability of the active material at the time of manufacturing the battery, the latter method is considered to be more preferable. That is, it can be said that it is simpler to use a lithium nickel-containing compound which is a discharge product of nickel oxyhydroxide as the positive electrode active material, and to manufacture the battery using the discharged active material such as graphite for the negative electrode. Because the active material is in a discharged state,
By increasing the stability against oxygen and moisture, the necessity of controlling the exposure atmosphere is reduced and the production equipment can be simplified, which is advantageous in terms of cost.

[0006] However, lithium nickel-containing compounds, which are the discharge products of nickel oxyhydroxide, are currently obtained only by electrochemical reduction of nickel oxyhydroxide in an organic electrolyte containing a lithium salt. . Therefore, in order to apply the above-described battery manufacturing method, an electrode using nickel oxyhydroxide as an active material is once manufactured, and a lithium nickel-containing compound which is a discharge product thereof is electrochemically prepared, and then an electrolytic solution is prepared. Requires a process of washing and drying. Implementing such a process is very difficult and has problems in terms of productivity, cost and quality. Therefore, establishment of a simple and effective method for synthesizing the lithium nickel-containing compound is required.

[0007]

As described above, nickel oxyhydroxide is expected to be a promising candidate for a positive electrode active material for a 3V non-aqueous electrolyte secondary battery, but is itself in a charged state. In order to produce a battery in combination with graphite, which is a negative electrode active material in a discharged state,
It is necessary to use a lithium nickel-containing compound in a discharged state also for the positive electrode active material. However, a simple and effective method for synthesizing this lithium nickel-containing compound has not yet been elucidated, and its establishment is desired.

[0008]

Means for Solving the Problems There are roughly two methods for producing a positive electrode active material for a non-aqueous electrolyte battery for solving the above problems. One is a method characterized by reacting a lithium compound having a reducing power to lithium or nickel oxyhydroxide and / or a derivative thereof with nickel oxyhydroxide and / or a derivative thereof in an organic solvent.

The other is to convert a lithium compound having no or relatively low reducing power to nickel oxyhydroxide and / or a derivative thereof into a compound having a reducing power to nickel oxyhydroxide and / or a derivative thereof. Nickel oxyhydroxide and / or
Or a method of reacting the derivative with an organic solvent in an organic solvent.

The method for producing a positive electrode active material for a non-aqueous electrolyte battery according to the present invention is not an electrochemical method in which a reaction proceeds by electric energy given from outside the reaction system, but a reaction product in the reaction system. This is a method in which the reaction proceeds with the oxidation-reduction power possessed.

As a result, a lithium-nickel-containing compound as a high-quality positive electrode active material for a non-aqueous electrolyte battery can be easily obtained, and a battery can be manufactured safely and easily using the compound.

Further, a non-aqueous electrolyte battery according to the present invention is characterized in that the lithium nickel-containing compound obtained by the above-mentioned production method is used as a positive electrode active material.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The method for producing a positive electrode active material for a non-aqueous electrolyte battery according to the present invention can be roughly divided into two types as described above.

One is a method characterized by reacting a lithium compound having a reducing power for lithium or nickel oxyhydroxide and / or a derivative thereof with nickel oxyhydroxide and / or a derivative thereof in an organic solvent. It is.

The other is to convert a lithium compound having no or relatively low reducing power to nickel oxyhydroxide and / or its derivative into a compound having reducing power to nickel oxyhydroxide and / or its derivative. Nickel oxyhydroxide and / or
Or a method of reacting the derivative with an organic solvent in an organic solvent.

As a specific example of the latter method, there is a method in which a substance having a reducing power for nickel oxyhydroxide and / or a derivative thereof is an organic compound. There is a method characterized in that the compound is an alcohol. Further, as an example of these applications, there is a method characterized in that a substance having a reducing power for nickel oxyhydroxide and / or a derivative thereof and an organic solvent are the same compound,
As a specific example, there is a method in which a substance having a reducing power for nickel oxyhydroxide and / or a derivative thereof and an organic solvent are alcohols.

The term “nickel oxyhydroxide” used herein means
Not limited to those having a stoichiometric composition represented by the chemical formula NiOOH, that is, so-called β-NiOOH, but also those having water molecules or alkali metal cations penetrating into the structure, so-called γ-NiOOH.

The term "nickel oxyhydroxide derivative" used herein refers to a substance obtained by substituting some of the elements constituting nickel oxyhydroxide with another element, for example, a substance obtained by substituting a part of nickel with cobalt. Refers to a substance in which part of hydrogen has been replaced with lithium.

For example, a nickel oxyhydroxide derivative in which nickel is partially substituted with cobalt or zinc is often used as an improved product of nickel oxyhydroxide as a positive electrode active material for nickel cadmium batteries or nickel metal hydride batteries. The chemical and chemical properties are similar to those of nickel oxyhydroxide, and the method for producing a lithium nickel-containing compound of the present invention can be applied similarly to nickel oxyhydroxide.

When a nickel oxyhydroxide derivative is used in the reaction instead of nickel oxyhydroxide, it is needless to say that a substance having a reducing power to the nickel oxyhydroxide derivative must be used.

Examples of the above-mentioned substances having a reducing power for nickel oxyhydroxide and / or a derivative thereof include NaBH ₄ ,
_{(I-C 4 H 9)} 2 AlH, anhydrous hydrazine, BH ₃ · TH
F, KI, H ₂ , Na, Cd, Fe, Zn, Li, hydrogen storage alloys storing hydrogen, and the like. Among organic substances, formaldehyde, cyclohexanone, cyclopentanone, hydroquinone, p-aminophenol, and alcohols Can be mentioned. Further, examples of alcohols having a reducing power for nickel oxyhydroxide and / or a derivative thereof include methanol, ethanol, allyl alcohol, benzyl alcohol, and cinnamyl alcohol.

Examples of lithium compounds having a reducing power for nickel oxyhydroxide and / or a derivative thereof include n-butyllithium, s-butyllithium, t-butyllithium, n-hexyllithium, phenyllithium, and 2-thienyl. Lithium, lithium iodide, lithium borohydride, lithium aluminum hydride, lithium amide, lithium dimethylamide, lithium diethylamide, lithium diisopropylamide, lithium dicyclohexylamide, lithium bis (trimethylsilyl) amide, lithium trimethylsilanolate, lithium acetylide ethylenediamine complex , Lithium (trimethylsilyl) acetylide, lithium phenyl acetylide, lithium 9-BBN hydride, lithium methoxide, lithium ethyl By selecting from among oxide, lithium isopropoxide, lithium t-butoxide, lithium phenoxide, lithium thiophenoxide, lithium cyclopentadienyl, lithium hydride, lithium nitride, and the like, the yield of the desired lithium nickel-containing compound is obtained. Can be further improved.

The lithium compound having no reducing power for nickel oxyhydroxide and / or its derivative is preferably LiClO ₄ , LiPF ₆ , LiAs
It is preferable to use salts having relatively high solubility in organic solvents, such as F ₆ , LiBF ₄ and LiCF ₃ SO ₃ . A substance having a reducing power for lithium or nickel oxyhydroxide and / or a derivative thereof, a lithium compound having no reducing power for nickel oxyhydroxide and / or a derivative thereof, and a reaction with nickel oxyhydroxide and / or a derivative thereof include: A method in which both powders and a solution are brought into direct contact with each other in an organic solvent may be used, or a method in which electrodes containing both are prepared and immersed in an organic solvent to bring both electrodes into electrical contact may be used.

As the substance having a reducing power for nickel oxyhydroxide and / or a derivative thereof, it is preferable to use an organic compound, more preferably an alcohol, thereby simplifying the reaction system and reducing the production cost. Can be realized. Similar effects can be expected even when alcohols are used as the reaction solvent.

The lithium compound having no reducing power for nickel oxyhydroxide and / or its derivative is preferably LiClO ₄ , LiPF ₆ , LiAs
By using a salt having relatively high solubility in an organic solvent such as F ₆ , LiBF ₄ and LiCF ₃ SO ₃ to increase the lithium ion concentration in the reaction solution, the reaction yield can be further increased.

A lithium compound having a reducing power for nickel oxyhydroxide and / or its derivative and a lithium compound having no or relatively weak reducing power for nickel oxyhydroxide and / or its derivative are used simultaneously. By doing so, a similar effect can be expected.

[0027]

The present invention will be described below with reference to preferred embodiments, but the scope of the present invention is not limited thereto.

Example 1 In an inert gas atmosphere,
10 g of nickel oxyhydroxide powder is mixed with a hexane solution (1.6 M) of n-butyllithium as a lithium compound having a reducing power for nickel oxyhydroxide (1.6 M).
Add to ml with stirring. After stirring was continued for 2 days, the unreacted n-butyllithium was washed with the solvent used for the reaction (here, hexane) and dried to obtain the positive electrode active material lithium nickel-containing compound according to the present invention.

A mixture of the lithium nickel-containing compound and 5 wt% of acetylene black as a conductive material, 5 wt% of polyvinylidene difluoride and 3 wt% of n-methyl-2-pyrrolidole as a binder was added to a dry room. And then applied to a current collector aluminum net, and then dried at 100 ° C. to produce a 20 mm × 20 mm positive electrode plate used in the present invention.

One positive electrode plate manufactured as described above, two lithium metal plates of the same size as the counter electrode, and 1
A battery A including the positive electrode active material a obtained by the method according to the present invention was manufactured using 50 ml of a mixed solvent of ethylene carbonate and diethyl carbonate containing M lithium perchlorate.

[Example 2] In the same manner as in Example 1, except that t-butyllithium was used instead of n-butyllithium as the lithium compound having a reducing power for nickel oxyhydroxide, the production method according to the present invention was used. Battery B provided with the obtained positive electrode active material b was produced.

[Example 3] In the same manner as in Example 1 except that phenyllithium was used instead of n-butyllithium as a lithium compound having a reducing power for nickel oxyhydroxide, a lithium compound was obtained by the production method according to the present invention. Battery C provided with positive electrode active material c was produced.

[Example 4] A lithium compound having a reducing power to nickel oxyhydroxide was obtained by the production method according to the present invention in the same manner as in Example 1 except that lithium amide was used instead of n-butyllithium. Battery D provided with positive electrode active material d was produced.

Example 5 The process of the present invention was carried out in the same manner as in Example 1 except that lithium diisopropylamide was used instead of n-butyllithium as the lithium compound having a reducing power for nickel oxyhydroxide. The battery E provided with the positive electrode active material e was manufactured.

Example 6 The process of the present invention was carried out in the same manner as in Example 1 except that lithium was used instead of n-butyllithium as a lithium compound having a reducing power for nickel oxyhydroxide. Battery F provided with positive electrode active material f was produced.

Example 7 A battery G was prepared in the same manner as in Example 1 except that ethyl alcohol was used as the organic solvent, and provided with the positive electrode active material g obtained by the production method according to the present invention.

Example 8 As a lithium compound having no reducing power for nickel oxyhydroxide, LiClO _{4 was used.}
And a battery H provided with the positive electrode active material h obtained by the production method according to the present invention in the same manner as in Example 1 except that a material having a reducing power for nickel oxyhydroxide and methyl alcohol as an organic solvent were used. Produced.

Example 9 LiClO ₄ as a lithium compound having no reducing power for nickel oxyhydroxide
The positive electrode active material i obtained by the production method according to the present invention is the same as in Example 1, except that lithium iodide is used as the substance having a reducing power for nickel oxyhydroxide, and acetonitrile is used as the organic solvent. The battery I provided was produced.

Example 10 LiPF ₆ was used as a lithium compound having no reducing power for nickel oxyhydroxide.
The positive electrode active material j obtained by the production method according to the present invention is the same as in Example 1 except that lithium iodide is used as the substance having a reducing power for nickel oxyhydroxide, and acetonitrile is used as the organic solvent. The battery J provided was produced.

Example 11 As a lithium compound having no reducing power for nickel oxyhydroxide, LiAsF was used.
₆ , positive electrode active material k obtained by the production method according to the present invention in the same manner as in Example 1 except that lithium iodide is used as a substance having a reducing power for nickel oxyhydroxide and acetonitrile is used as an organic solvent. Battery K with
Was prepared.

Example 12 As a lithium compound having no reducing power for nickel oxyhydroxide, LiClO was used.
₄ , a production method according to the present invention in the same manner as in Example 1 except that ethyl alcohol is used as a substance having a reducing power for nickel oxyhydroxide and acetonitrile is used as an organic solvent in a volume ratio of 8: 2. A battery L provided with the positive electrode active material 1 obtained by the above was prepared.

Example 13 LiClO was used as a lithium compound having no reducing power for nickel oxyhydroxide.
₄ , a production method according to the present invention was carried out in the same manner as in Example 1 except that ethyl alcohol was used as a substance having a reducing power for nickel oxyhydroxide, and acetonitrile was used as an organic solvent in a volume ratio of 1: 1. A battery M provided with the positive electrode active material m obtained by the above was manufactured.

Example 14 As a lithium compound having no reducing power for nickel oxyhydroxide, LiClO was used.
₄ , a production method according to the present invention was carried out in the same manner as in Example 1 except that ethyl alcohol was used as a substance having a reducing power for nickel oxyhydroxide, and acetonitrile was used as an organic solvent in a volume ratio of 1: 1. A battery N provided with the positive electrode active material n obtained by the above was manufactured.

[Conventional Example 1] For comparison, a conventional battery O was prepared in the same manner as in Example 1 except that nickel oxyhydroxide was used as the positive electrode active material.

[Identification of Product] The positive electrode active materials obtained in Examples 1 to 7 and a nickel oxyhydroxide positive electrode plate as a comparative example were obtained by cathode reduction in a nonaqueous electrolyte containing a lithium salt. The powder X-ray diffraction pattern of the compound is shown in FIG. The chemical formula of this compound is NiOOH
The composition is close to Li _0.94 . For b and c, since the sample was sealed in a polyethylene (PE) bag, the diffraction peak corresponding to PE was also observed.

[Battery Evaluation Test] The batteries using the positive electrode active materials obtained in the above Examples 1 to 7 and the batteries shown in the Comparative Examples were subjected to the following tests at 25 ° C. and a current density of 0.1 mA / cm ² .
After charging to 2 V, discharging was performed to 1.5 V at the same current density.

The first cycle charge / discharge characteristics of the battery A according to the present invention and the conventional battery O (battery A starts from charging,
FIG. 2 shows a conventional battery O starting from discharging.

[Evaluation Results] In FIG. 1, the X-ray diffraction patterns of the positive electrode active materials obtained in Examples 1 to 7 of the present invention and the lithium nickel-containing compound obtained electrochemically agree well. I have. Although not shown, the X-ray diffraction patterns of the positive electrode active materials obtained in Examples 8 to 14 were in good agreement with the pattern shown in FIG. This confirms that the lithium nickel-containing compound can be synthesized chemically, not electrochemically, by the method according to the present invention.

In FIG. 2, the initial charge curve of the battery A according to the present invention matches the shape of the charge curve after the initial discharge in the conventional battery O using nickel oxyhydroxide as the positive electrode active material. The characteristics are also consistent. Therefore, it can be seen that the positive electrode active material obtained according to the present invention is exactly the active material in the discharged state of nickel oxyhydroxide. Batteries B, C, D, E, F, G, H,
I, J, K, L, M, and N also exhibited the same charge / discharge characteristics as Battery A.

As lithium compounds having reducing power to nickel oxyhydroxide, s-butyllithium,
n-hexyllithium, 2-thienyllithium, lithium iodide, lithium borohydride, lithium aluminum hydride, lithium dimethylamide, lithium diethylamide, lithium dicyclohexylamide, lithium bis (trimethylsilyl) amide, lithium trimethylsilanolate, lithium acetylide ethylenediamine Complex, lithium (trimethylsilyl) acetylide, lithium phenylacetylide, lithium 9-BBN hydride, lithium methoxide, lithium ethoxide, lithium isopropoxide, lithium t-butoxide, lithium phenoxide, lithium thiophenoxide, cyclopentadienyl lithium, hydrogen Does not have a reducing power when selected from lithium oxide and lithium nitride or nickel oxyhydroxide Even when selected from among LiBF ₄ and LiCF ₃ SO ₃ as a lithium compound,
A lithium nickel-containing compound that could function as a positive electrode active material in a discharged state was obtained.

When various nickel oxyhydroxide derivatives were used instead of nickel oxyhydroxide, the same reaction proceeded, and a lithium nickel-containing compound capable of functioning as a positive electrode active material in a discharged state was obtained.

As the organic solvent to be used, various organic solvents such as hexane and ethyl alcohol can be used.

[0053]

The present invention relates to a method for producing a lithium nickel-containing compound. One is a lithium compound having a reducing power for lithium or nickel oxyhydroxide and / or a derivative thereof; Alternatively, the method is characterized in that a derivative thereof is reacted in an organic solvent. The other is to use a lithium compound having no reducing power or a relatively weak reducing power for nickel oxyhydroxide and / or a derivative thereof with a substance having a reducing power for nickel oxyhydroxide and / or a derivative thereof. The method comprises reacting nickel oxyhydroxide and / or a derivative thereof in an organic solvent.

According to the present invention, it is possible to produce an active material in a discharged state of nickel oxyhydroxide, which is a high-capacity positive electrode active material. It is much easier to produce a battery in combination with a system negative electrode. In addition, by using a more stable active material in a discharged state, it is possible to handle easily and safely. Therefore, the industrial value of the present invention is extremely large.

[Brief description of the drawings]

FIG. 1 shows positive electrode active materials a, b, c, d, e, and
It is the figure which compared the powder X-ray-diffraction pattern of f, g, and the conventional positive electrode active material nickel oxyhydroxide.

FIG. 2 is a diagram comparing charge and discharge characteristics of a battery A according to the present invention and a conventional battery O.

Claims (11)

[Claims] 1. A method for producing a lithium nickel-containing compound, comprising reacting (1) lithium and (2) nickel oxyhydroxide and / or a derivative thereof in an organic solvent. 2. A method comprising reacting (1) a lithium compound having a reducing power for nickel oxyhydroxide and / or a derivative thereof and (2) nickel oxyhydroxide and / or a derivative thereof in an organic solvent. A method for producing a lithium nickel-containing compound. 3. A reaction between (1) a lithium compound, (2) a substance having a reducing power for nickel oxyhydroxide and / or a derivative thereof, and (3) nickel oxyhydroxide and / or a derivative thereof in an organic solvent. A method for producing a lithium nickel-containing compound, comprising: 4. The method for producing a lithium nickel-containing compound according to claim 3, wherein the substance having a reducing power for nickel oxyhydroxide and / or a derivative thereof is an organic compound. 5. The method for producing a lithium nickel-containing compound according to claim 4, wherein the substance having a reducing power for nickel oxyhydroxide and / or its derivative is an alcohol. 6. The method for producing a lithium nickel-containing compound according to claim 4, wherein the substance having a reducing power for nickel oxyhydroxide and / or a derivative thereof and the organic solvent are the same compound. 7. The method for producing a lithium nickel-containing compound according to claim 6, wherein the substance having a reducing power for nickel oxyhydroxide and / or a derivative thereof and the organic solvent are alcohols. 8. The method for producing a lithium nickel-containing compound according to claim 3, wherein the substance having a reducing power for nickel oxyhydroxide and / or a derivative thereof is lithium or a lithium compound. 9. A non-aqueous electrolyte battery using the lithium nickel-containing compound according to the method of claim 1 as a positive electrode active material. 10. A non-aqueous electrolyte battery using the lithium nickel-containing compound according to the method of claim 2 as a positive electrode active material. 11. A non-aqueous electrolyte battery using the lithium nickel-containing compound according to the method of claim 3 as a positive electrode active material.