JP4161382B2 - Process for producing two-layer structured particulate composition - Google Patents

Description

【０１０６】
【表２】

【０１０７】
実施例２０
実施例２で調製した中心部がリチウムニッケル複合酸化物（ＬｉＮｉＯ_２）からなり、表層部がリチウムコバルト複合酸化物（ＬｉＣｏＯ_２）からなる２層構造粒子状組成物の粉末（正極活物質）、アセチレンブラック（導電剤）及びポリテトラフルオロエチレン（結着剤）を重量比８７：６．５：６．５にてよく混練して、合剤を調製した。この合剤を正極集電体としての清浄なステンレスメッシュ（穴径２０ｍｍ）に均一に塗布し、２００ｋｇ／ｃｍ^２の圧力にて圧着した後、減圧下、１５０℃で１７時間乾燥して、正極を作製した。負極として円板状の金属リチウム箔（直径２０ｍｍ、厚さ０．２ｍｍ）を用いた。また、セパレーターとしてポリピロピレンからなる多孔質フィルムを用いた。
【０１０８】
また、非水電解液は、過塩素酸リチウム（ＬｉＣｌＯ_４）のプロピレンカーボネート溶液（１Ｍ）と１，２−ジメトキシエタンとの混合物（１：１）で、水分を２０ｐｐｍ以下としたものを用い、これを上記セパレーターに含浸させた。
これらの構成要素を用いて、図１に示すようなリチウムイオン二次電池を製作し、これを用いて、電流値を１．０ｍＡ／ｃｍ^２の一定電流とし、電池電圧４．２〜２．０Ｖの間で充放電を繰り返して、電池特性を調べた。その結果、本発明によるリチウム二次電池の初期容量は１８２ｍＡｈ／ｇと高く、また、５０サイクル目の充放電容量は１サイクル目の９０％であって、サイクル特性にもすぐれる。
【０１０９】
また、この電池を８０℃で長時間保持したときも、電解液は、リチウムコバルト複合酸化物（ＬｉＣｏＯ_２）を正極材活物質として用いた場合と同様であって、殆ど分解しておらず、高温での安定性にすぐれることも確認された。
【図面の簡単な説明】
【図１】は、リチウムイオン二次電池の一例を示す断面図である。
【図２】は、実施例１において得られた水酸化ニッケルの二次粒子粉末の走査型電子顕微鏡写真（倍率５００倍）である。
【図３】は、上記水酸化ニッケルの粒子に水酸化コバルトを被覆してなる水酸化ニッケルコバルトのＸ線回折図である。
【図４】は、上記水酸化ニッケルコバルトの走査型電子顕微鏡写真（倍率５００倍）である。
【図５】は、上記水酸化ニッケルコバルトの粒子断面のＥＰＭＡ（電子線プローブマイクロアナライザー）による線分析を示す写真（倍率１０００倍）である。
【図６】は、実施例１において得られた中心部がニッケル酸リチウム（ＬｉＮｉＯ_２）からなり、表層部がコバルト酸リチウム（ＬｉＣｏＯ_２）からなる２層構造の球状粒子の断面のＥＰＭＡ（電子線プローブマイクロアナライザー）による線分析を示す写真（倍率１０００倍）である。
【符号の説明】
１…正極、２…負極、３…セパレータ、４…電池容器、５…正極集電体、６…正極用リード線、７…負極集電体、８…負極用リード線。[0001]
BACKGROUND OF THE INVENTION
  The present invention is a two-layer structure particulate composition that can be suitably used as a positive electrode active material in a lithium ion secondary battery.Manufacturing methodAbout.
[0002]
[Prior art]
Lithium-nickel composite oxide is one of materials that have recently attracted attention as a positive electrode active material in lithium-ion secondary batteries used as high-power, high-energy density batteries, for example, notebook personal computers, PHS, and mobile phones. One. This lithium nickel composite oxide is, for example, “spherical LiCoO by ultrasonic spray pyrolysis.₂Synthesis of Fine Powder and Application to Active Materials for Lithium Rechargeable Batteries "(Takashi Sugawara, Yoshihiko Saito, Akiaki Yanagawa, Nobuo Ogata, Kokiyoshi Yoshida, Masayuki Takashima, Satoshi Yonezawa, Yasuharu Mizuno, Kenji Nagata, Kenji Ogawa, Journal of LiMO as described in Journal of the Ceramic Society of Japan, Volume 101, pages 1159 to 1163 (1993)₂(Wherein M is Cr, Mn, Ni, Fe, Co or V), which is one of a group of compounds represented by LiCoO₂Similarly, since the charge / discharge voltage is particularly high, it is very useful as a positive electrode active material.
[0003]
When such a lithium nickel composite oxide is used as a positive electrode active material of a lithium ion secondary battery, in order to improve its performance, a lithium nickel composite oxide having a changed composition or a lithium nickel composite oxide Improvements in physical properties have been proposed.
[0004]
Japanese Patent Application Laid-Open No. 4-328278 discloses that the composition of the lithium nickel composite oxide is changed._xMO₂(M represents a transition metal. 0.05 ≦ x <1.10)₃A content of 0.5 to 15% by weight is described.
[0005]
JP-A-6-150929 discloses LiNiO containing at least one of Na and K.₂Is described. JP-A-62-256371, JP-A-5-36411, and JP-A-7-307150 disclose LiNiO containing elements such as Co, V, Cr, Fe, P, B, Si, Mo, and W.₂Is described. As an improvement of the physical properties of a lithium nickel composite oxide, Japanese Patent Application Laid-Open No. 7-10590 discloses LiNiO composed of secondary and aggregated particles whose primary particles are 1 μm or less.₂Particles are disclosed. This LiNiO₂It is described that the particles are excellent in reproducibility and can obtain a high charge / discharge amount when used as a positive electrode active material of a lithium ion secondary battery.
[0006]
However, even if the battery is manufactured using the lithium nickel composite oxide thus improved, when the battery is left in a high-temperature environment for a long time, for example, the battery is mounted during midsummer day. When left in an automobile where a mobile phone is stopped, the lithium-nickel composite oxide of the positive electrode active material reacts with the non-aqueous electrolyte, and part of the non-aqueous electrolyte decomposes and gasifies, increasing the internal pressure of the battery container. As a result, the battery may explode, causing damage such as damage to the battery-equipped device, causing a fire, and causing environmental hazards.
[0007]
In order to solve such problems, Japanese Patent Laid-Open No. 8-138670 discloses a lithium nickel composite oxide (LiNiO₂) Non-aqueous solvent secondary batteries have been proposed in which the surface layer of the powder is a layer having a high concentration of different kinds of transition elements such as cobalt as the positive electrode active material of the secondary battery. However, like the lithium nickel composite oxide powder shown in the examples of the above publication, the concentration of a different element, such as cobalt, present in the surface layer of the powder particles is low, and the atomic ratio of the different element to nickel is 0. The solution to the above-mentioned problem is still not sufficient.
[0008]
[Problems to be solved by the invention]
  The present invention has been made in order to solve the above-described problems in conventional lithium nickel composite oxides, and has a two-layer structure composed of lithium composite oxides having different metal species constituting the oxides. Particulate composition havingManufacturing methodBecauseThis particulate compositionLithium composite oxide particles that can suppress decomposition of the non-aqueous electrolyte to a minimum even when kept at a high temperature by constituting a lithium ion secondary battery using a positive electrode active material as a positive electrode active material CompositionManufacturing methodThe purpose is to provide.
[0009]
More specifically, when a lithium ion secondary battery using lithium nickel composite oxide particles as a positive electrode active material is held at a high temperature, the decomposition reaction of the nonaqueous electrolyte at the interface between the active material particles and the nonaqueous electrolyte Occurs, decomposition gas is generated, the pressure in the battery container rises, and the battery may burst. Therefore, in order to suppress the decomposition of the non-aqueous electrolyte, the interface between the active material particles and the non-aqueous electrolyte should be made as small as possible, that is, the specific surface area of the active material particles should be made as small as possible. However, in general, when the specific surface area of the active material particles is reduced, the charge / discharge capacity is lowered and the charge / discharge response is also lowered. Therefore, the use of active material particles having a specific surface area capable of obtaining battery characteristics in which these characteristics are balanced has been an important requirement for manufacturing a lithium ion secondary battery.
[0010]
  However, the present inventors have disclosed a particulate composition for an active material for a lithium ion secondary battery having excellent high-temperature stability regardless of the specific surface area of the active material particles.Manufacturing methodAs a result, the present invention has been achieved.
[0011]
[Means for Solving the Problems]
  According to the present invention, a nickel hydroxide powder is dispersed in water, and in the presence of ammonium ions, a cobalt salt aqueous solution and a caustic aqueous solution are continuously added to cause a reaction. A center layer made of lithium nickel composite oxide and a surface layer made of lithium cobalt composite oxide are prepared by preparing particles formed by coating cobalt hydroxide on the surface, mixing this with lithium hydroxide and firing. And having a cobalt / (nickel + cobalt) atomic ratio in the range of 0.2 to 1 from the particle surface to a depth of 0.1 μm, a two-layered particulate composition for a positive electrode active material for a lithium ion secondary battery A method of manufacturing an article is provided.
[0012]
  Further, according to the present invention, nickel hydroxide powder is dispersed in water, and in the presence of ammonium ions, a cobalt salt aqueous solution and a caustic aqueous solution are continuously added to cause a reaction. Prepare particles by coating the surface of the particles with cobalt hydroxide, oxidize them to prepare nickel cobalt oxide, and then hydrothermally react with lithium hydroxide in an aqueous dispersion medium. A cobalt / (nickel + cobalt) atomic ratio from the particle surface to a depth of 0.1 μm is 0.2. A method for producing a two-layered particulate composition for a positive electrode active material for a lithium ion secondary battery in the range of ˜1 is provided..
[0014]
DETAILED DESCRIPTION OF THE INVENTION
The two-layered particulate composition according to the present invention will be described in detail below.
The particulate composition according to the present invention is a particulate composition comprising a central layer and a surface layer. The central layer is made of a lithium nickel composite oxide, and the surface layer is made of a lithium cobalt composite oxide. However, the center layer and the surface layer may each contain other oxides or composite oxides as long as they do not adversely affect the battery characteristics.
[0015]
The two-layer structure particulate composition according to the present invention may have any shape as long as it has a two-layer structure. For example, the central layer, which is a primary particle composed of a lithium nickel composite oxide, is mixed with lithium cobalt composite oxide. In addition to those having a structure covered with a surface layer made of a material, the central layer, the surface layer, or both of them may be an aggregate of primary particles made of the respective complex oxides. As will be described later, the shape is preferably substantially spherical. However, the shape may be substantially cubic or other shapes.
[0016]
The shape and size of the particulate composition according to the present invention are not particularly limited, but when used as a positive electrode active material of a lithium ion secondary battery, the average particle diameter is 3 to 100 μm, It is preferably spherical. Thus, when the particulate composition is substantially spherical, it is preferable because it is excellent in filling property, that is, the packing density can be increased. Further, when the average particle size is less than 3 μm, when used as a positive electrode active material of a lithium ion secondary battery, the filling rate is low, so the electric capacity per unit volume of the battery is low, while the average When the particle diameter exceeds 100 μm, for example, the particles may pass through a separator made of a porous film of a polymer such as polypropylene, which may cause a short circuit between the positive electrode and the negative electrode. In particular, the size of the particulate composition according to the present invention is preferably in the range of 3-50 μm, most preferably in the range of 5-30 μm.
[0017]
However, the particulate composition having a shape other than spherical may be used as a positive electrode active material for a lithium ion secondary battery, if necessary.
In the particulate composition according to the present invention, the central layer is made of a lithium nickel composite oxide, and preferably has the general formula (I)
Li_pNi_1-xA_xO_y
(In the formula, A is B, Mg, Al, Si, Sc, Ti, V, Cr, Mn, Fe, Co, Cu, Zn, Ga, Y, Zr, Nb, Mo, Ru, Sn, Sb, La. And at least one element selected from the group consisting of Ce, Pr, Nb, Hf, Ta and Pb, p is a number in the range of 0.90 to 1.10, and x is 0 to 0.25. The number of the range is shown, and y is the number of the range of 1.825 to 2.3.)
It consists of lithium nickel complex oxide represented by these.
[0018]
On the other hand, in the particulate composition according to the present invention, the surface layer is composed of a lithium cobalt composite oxide, and preferably the general formula (II)
Li_qCo_1-aZ_aO_b
(In the formula, Z is B, Mg, Al, Si, Sc, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Ga, Y, Zr, Nb, Mo, Ru, Sn, Sb, La. , Ce, Pr, Nd, Hf, Ta and Pb, at least one element selected from the group consisting of q, q represents a number in the range of 0.90 to 1.10, and a is 0 to 0.25. The number of the range is shown, and b is the number of the range of 1.825 to 2.3.)
It consists of lithium cobalt complex oxide represented by these.
[0019]
In the above general formulas (I) and (II), by using a particulate composition in which x or a is in the range of 0 to 0.25 as a positive electrode active material in a lithium ion secondary battery, storage characteristics of the battery Can be further enhanced. However, when x or a exceeds 0.25, the charge / discharge capacity of the battery is greatly reduced, which is not preferable.
[0020]
As described above, the two-layer structure particulate composition according to the present invention comprises a central layer made of a lithium nickel composite oxide and a surface layer made of a lithium cobalt composite oxide. Although it has a high charge / discharge capacity of 190 mAh / g or more, it is easy to decompose the non-aqueous electrolyte at a high temperature. On the other hand, the lithium cobalt composite oxide has a charge / discharge capacity lower than that of the lithium nickel composite oxide, about 150 mAh / g. However, it is difficult to decompose the non-aqueous electrolyte even when kept at a high temperature. Thus, the particulate composition according to the present invention uses only the advantages of the two lithium composite oxides and is combined so as to compensate for the drawbacks.
[0021]
That is, when the two-layer structured particulate composition according to the present invention is used as a positive electrode active material of a lithium ion secondary battery, only the surface-laminated lithium cobalt composite oxide comes into contact with the non-aqueous electrolyte. As described above, the lithium cobalt composite oxide is difficult to decompose the non-aqueous electrolyte even when kept at a high temperature, and thus contributes to the stability of the battery. It has a lithium nickel composite oxide having a large charge / discharge capacity as a central layer, and therefore has a high charge / discharge capacity as a whole.
[0022]
Thus, when the two-layered particulate composition according to the present invention is used as a positive electrode active material of a lithium ion secondary battery, a secondary battery having excellent high temperature stability and high charge / discharge capacity can be obtained.
[0023]
  In the present invention, the quantitative ratio between the surface layer and the center layer is not particularly limited, and when the charge / discharge capacity is emphasized, the ratio of the center layer is increased and the high temperature stability is emphasized. The ratio of the surface layer may be increased, and an arbitrary ratio can be used depending on the target battery characteristics. However, in the two-layered particulate composition according to the present invention, the sum of the number of cobalt atoms and Z atoms in the surface layer (Co + Z) and the sum of the number of nickel atoms and A atoms in the center layer (Ni + A), that is, Of the surface layer (Co + Z)/ (Ni + A) atomic ratio of the central layer is usually in the range of 5/100 to 50/100, and preferably in the range of 10/100 to 30/100.
[0024]
In the two-layer structure particulate composition according to the present invention, the surface of the particle is ideally completely covered with the lithium cobalt composite oxide. However, in practice, the particle surface is 0.1 μm from the particle surface. By using such a composition as a positive electrode active material in a lithium ion secondary battery when the cobalt / (nickel + cobalt) atomic ratio to the depth is in the range of 0.2 to 1, the stability of the target battery can be improved. Sex can be obtained. In particular, according to the present invention, the cobalt / (nickel + cobalt) atomic ratio from the particle surface to a depth of 0.1 μm is preferably in the range of 0.3 to 1, more preferably 0.5 to 1. It is preferable to be in the range.
[0025]
Furthermore, in the two-layer structure particulate composition according to the present invention, the lithium nickel composite oxide represented by the formula (I) is usually the ratio of Li atoms to the sum of Ni atoms and A atoms, that is, Li / ( Ni + A) a stoichiometric composite oxide with an atomic ratio of 1, ie, p = 1, but a non-stoichiometric composite oxide with an Li / (Ni + A) atomic ratio of 1 There may be. That is, p is a number in the range of 0.90 to 1.10.
[0026]
Similarly, in the two-layer structure particulate composition according to the present invention, the lithium cobalt composite oxide represented by the formula (II) usually has a ratio of Li atoms to the sum of Co atoms and Z atoms, that is, Li / A stoichiometric composite oxide having a (Co + Z) atomic ratio of 1, that is, q = 1, but a non-stoichiometric composite oxide having an Li / (Co + Z) atomic ratio of 1 It may be. That is, q is a number in the range of 0.90 to 1.10.
[0027]
The two-layer structured particulate composition according to the present invention can be produced, for example, by the following method. According to such a production method, a two-layered particulate composition according to the present invention in which the cobalt / (nickel + cobalt) atomic ratio from the surface to a depth of 0.1 μm is in the range of 0.2 to 1 is obtained. Can do.
[0028]
(1) To a slurry in which nickel hydroxide powder is dispersed in water, a cobalt salt aqueous solution and a caustic aqueous solution are continuously added and reacted in the presence of ammonium ions, whereby water is added to the surface of the nickel hydroxide particles. Particles coated with cobalt oxide are prepared. The particulate composition according to the present invention can be obtained by mixing this with lithium hydroxide and baking it.
[0029]
(2) In the same manner as described above, particles obtained by coating the surface of nickel hydroxide particles with cobalt hydroxide are prepared and oxidized to prepare nickel hydroxide-containing cobalt. The particulate composition according to the present invention can be obtained by performing a hydrothermal reaction with lithium hydroxide in an aqueous dispersion medium at high temperature and pressure.
[0030]
The lithium ion secondary battery according to the present invention uses the two-layered particulate composition as described above as a positive electrode active material.
[0031]
An example of a lithium ion secondary battery is shown in FIG. The positive electrode 1 and the negative electrode 2 are accommodated in the battery container 4 so as to face each other via a separator 3 impregnated with a nonaqueous electrolyte solution. The positive electrode 1 is connected to a positive electrode lead wire 6 via a positive electrode current collector 5. The negative electrode 2 is connected to the negative electrode lead wire 8 via the negative electrode current collector 7, and chemical energy generated inside the battery is taken out from the lead wires 6 and 8 to the outside as electrical energy. Configured to get.
[0032]
The particulate composition according to the present invention is mixed with a conductive agent, a binder, a filler, and the like, kneaded to form a mixture, and this is applied to a positive electrode current collector made of, for example, a stainless mesh, and pressed. Then, heat drying under reduced pressure to obtain a positive electrode. Further, the mixture may be formed into an appropriate shape such as a disk, and may be heat treated under vacuum as necessary to form a positive electrode.
[0033]
The conductive agent is not particularly limited as long as it is an electron conductive material that does not cause a chemical change in a lithium ion secondary battery. For example, natural graphite, artificial graphite, carbon black, acetylene black, ketjen black, carbon fiber, A metal powder, a metal fiber, a polyphenylene derivative, etc. can be mentioned. These may be used alone or in combination of two or more.
[0034]
Although the compounding quantity of the said electrically conductive agent in the said mixture is not specifically limited, Usually, 1 to 50 weight% is preferable and the range of 2 to 30 weight% is especially preferable. Also, the binder is not particularly limited. For example, starch, polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, regenerated cellulose, diacetyl cellulose, polyvinyl chloride, polyvinyl pyrrolidone, tetrafluoroethylene, polyvinylidene fluoride, polyethylene, Examples thereof include polypropylene, ethylene-propylene-diene copolymer (EPDM), sulfonated EPDM, styrene-butadiene rubber, polybutadiene, fluororubber, and polyethylene oxide. These may be used alone or in combination of two or more. The blending amount of the binder in the mixture is not particularly limited, but is usually in the range of 1 to 50% by weight, and preferably in the range of 2 to 30% by weight.
[0035]
A filler is mix | blended with a positive electrode active material as needed. The filler is not particularly limited as long as it is a fibrous material that does not cause a chemical change in a lithium ion secondary battery, and examples thereof include olefin polymers such as polypropylene and polyethylene, fibers such as glass and carbon, and the like. it can. The blending amount of these fillers in the mixture is not particularly limited, but is usually preferably in the range of 0 to 30% by weight.
[0036]
  In the lithium ion secondary battery according to the present invention, the negative electrode is not particularly limited as long as it is conventionally used in a lithium ion secondary battery. For example, lithium, lithium alloy, stainless steel , Nickel, copper, titanium, aluminum, baked carbon, and the like.
[0037]
  Positive electrode and negative electrodeIsUsually formed on a current collector. Although it does not specifically limit as a collector, Usually, stainless steel, its mesh, etc. are used.
[0038]
Further, the non-aqueous electrolyte solution may be any one as long as it is conventionally known. For example, carbonates such as propylene carbonate, sulfolanes, lactones, 1,2-dimethoxyethane, etc. Examples thereof include those obtained by dissolving dissociable lithium salts such as lithium perchlorate and lithium hexafluorophosphate in an organic solvent such as ethers. As the separator, for example, a porous film made of a synthetic high molecular weight polymer such as polypropylene is used, but the separator is not limited thereto.
[0039]
【The invention's effect】
The two-layer structure particulate composition according to the present invention comprises a central layer made of lithium nickel composite oxide and a surface layer made of lithium cobalt composite oxide, and has a cobalt / coating depth of 0.1 μm from the particle surface. The (nickel + cobalt) atomic ratio is in the range of 0.2 to 1, and the lithium ion secondary battery according to the present invention uses such a two-layered particulate composition as a positive electrode active material.
[0040]
Therefore, according to the lithium ion secondary battery of the present invention, the non-aqueous electrolyte contacts only the lithium cobalt composite oxide of the surface layer which is difficult to decompose the non-aqueous electrolyte even when kept at a high temperature, The particulate composition has a lithium nickel composite oxide having a large charge / discharge capacity as a central layer, and the particulate composition has a high charge / discharge capacity as a whole. Thus, the lithium ion secondary battery according to the present invention has high temperature stability and high charge / discharge capacity.
[0041]
The lithium ion secondary battery according to the present invention is, for example, a notebook computer, a mobile phone, a cordless phone, a video movie, a liquid crystal television, an electric shaver, a portable radio, a headphone stereo, a backup power supply, a memory card and other electronic devices, a pacemaker. It can be suitably used for medical devices such as hearing aids.
[0042]
【Example】
EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples. In the following examples, the amount of transition elements (moles) in each raw material used for preparing the center layer and the surface layer, and the resulting surface layer element amount / center layer element amount molar ratio are shown in Table 1 and Table 2 summarizes the results.
[0043]
Example 1
A sodium hydroxide aqueous solution was continuously added to a nickel nitrate aqueous solution in the presence of ammonium ions and neutralized to obtain secondary particle powder made of substantially spherical nickel hydroxide in which primary particles were aggregated. This powder has a specific surface area of 148 m.²/ G. A scanning electron micrograph of this powder is shown in FIG.
[0044]
A slurry was obtained by dispersing 18.54 g of this spherical nickel hydroxide in 0.1 L of water in a 1.0 L glass beaker. To this slurry, 17.0 mL of cobalt nitrate aqueous solution (1.2 mol / L) was added in the presence of ammonium ions, and after sealing the beaker, nitrogen gas was added to the slurry at a rate of 0.5 L / min while stirring. Introduced and replaced with nitrogen. After 30 minutes, an aqueous sodium hydroxide solution (0.11 mol / L) was added at a rate of 1.0 mL / min for 8 hours using a metering pump. The precipitate thus obtained was filtered, washed with water, and dried for one day at 60 ° C. in an electric dryer to obtain about 20 g of powder.
[0045]
As a result of X-ray diffraction analysis of this powder, as shown in FIG. 3, nickel hydroxide (Ni (OH))₂Only the peak of) was confirmed. Further, as shown in FIG. 4, a scanning electron micrograph of this powder was composed of substantially spherical particles.
[0046]
Further, as shown in FIG. 5, when the particle cross-section was analyzed by EPMA (electron beam probe microanalyzer), it was confirmed that nickel was unevenly distributed in the center of the particle and cobalt was unevenly distributed in the surface of the particle. It was done.
[0047]
From the above analysis results, the powder has a crystalline nickel hydroxide (Ni (OH)) at the center.₂), And the surface layer is amorphous cobalt hydroxide (Co (OH))₂) To be substantially spherical particles.
[0048]
After 10.2 g of this powder was mixed with 4.2 g of lithium hydroxide monohydrate, it was placed in an alumina crucible and baked at 800 ° C. for 10 hours in an oxygen atmosphere to obtain a black powder. The center of this powder was lithium nickel composite oxide (LiNiO) based on X-ray diffraction, line analysis of cobalt and nickel by EPMA, and observation with a scanning electron microscope.₂And the surface layer portion is a lithium cobalt composite oxide (LiCoO).₂) Was confirmed to be a spherical particle having a two-layer structure. Furthermore, when the cobalt / (nickel + cobalt) atomic ratio from the particle surface to a depth of 0.1 μm was measured by Auger electron spectroscopy, it was 0.2 or more.
[0049]
Example 2
A slurry was obtained by dispersing 18.54 g of the spherical nickel hydroxide prepared in Example 1 in 0.1 L of water in a 1.0 L glass beaker. To this slurry, 34.0 mL of an aqueous cobalt nitrate solution (1.2 mol / L) was added in the presence of ammonium ions. After sealing the beaker, nitrogen gas was added to the slurry at a rate of 0.5 L / min while stirring. Introduced and replaced with nitrogen. After 30 minutes, an aqueous sodium hydroxide solution (0.22 mol / L) was added at a rate of 1.0 mL / min with a metering pump for 8 hours. The precipitate thus obtained was filtered, washed with water, and dried for one day at 60 ° C. in an electric dryer to obtain about 20 g of powder.
[0050]
When this powder was analyzed by X-ray diffraction, nickel hydroxide (Ni (OH))₂) Was confirmed, and this powder consisted of substantially spherical particles according to observation with a scanning electron microscope. Further, when the cross section of the particle was analyzed by EPMA (electron probe microanalyzer), it was confirmed that nickel was unevenly distributed in the center of the particle and cobalt was unevenly distributed in the surface of the particle.
[0051]
From the above analysis results, the particles have a crystalline nickel hydroxide (Ni (OH)) at the center.₂), And the surface layer is amorphous cobalt hydroxide (Co (OH))₂) To be substantially spherical particles.
[0052]
After mixing lithium hydroxide monohydrate 5.04g with 13.37g of this powder, it put into the crucible made from an alumina, and baked at 600 degreeC for 10 hours in oxygen atmosphere, and obtained black powder. The center of this powder was lithium nickel composite oxide (LiNiO) based on X-ray diffraction, line analysis of cobalt and nickel by EPMA, and observation with a scanning electron microscope.₂And the surface layer portion is a lithium cobalt composite oxide (LiCoO).₂) Was confirmed to be a spherical particle having a two-layer structure. Furthermore, when the cobalt / (nickel + cobalt) atomic ratio from the particle surface to a depth of 0.1 μm was measured by Auger electron spectroscopy, it was 0.2 or more.
[0053]
Example 3
A slurry was obtained by dispersing 18.54 g of the spherical nickel hydroxide prepared in Example 1 in 0.1 L of water in a 1.0 L glass beaker. To this slurry was added 68.0 mL of an aqueous cobalt nitrate solution (1.2 mol / L) in the presence of ammonium ions, and after sealing the beaker, nitrogen gas was added to the slurry at a rate of 0.5 L / min while stirring. Introduced and replaced with nitrogen. After 30 minutes, an aqueous sodium hydroxide solution (0.44 mol / L) was added at a rate of 1.0 mL / min with a metering pump for 8 hours. The precipitate thus obtained was filtered, washed with water, and dried for one day at 60 ° C. in an electric dryer to obtain about 20 g of powder.
[0054]
When this powder was analyzed by X-ray diffraction, nickel hydroxide (Ni (OH))₂) Was confirmed, and this powder consisted of substantially spherical particles according to observation with a scanning electron microscope. Further, when the cross section of the particle was analyzed by EPMA (electron probe microanalyzer), it was confirmed that nickel was unevenly distributed in the center of the particle and cobalt was unevenly distributed in the surface of the particle.
[0055]
From the above analysis results, the particles have a crystalline nickel hydroxide (Ni (OH)) at the center.₂), And the surface layer is amorphous cobalt hydroxide (Co (OH))₂) To be substantially spherical particles.
[0056]
After 9.28 g of this powder was mixed with 4.2 g of lithium hydroxide monohydrate, it was placed in an alumina crucible and fired at 800 ° C. for 10 hours in an oxygen atmosphere to obtain a black powder. The center of this powder was lithium nickel composite oxide (LiNiO) based on X-ray diffraction, line analysis of cobalt and nickel by EPMA, and observation with a scanning electron microscope.₂And the surface layer portion is a lithium cobalt composite oxide (LiCoO).₂) Was confirmed to be a spherical particle having a two-layer structure. Furthermore, when the cobalt / (nickel + cobalt) atomic ratio from the particle surface to a depth of 0.1 μm was measured by Auger electron spectroscopy, it was 0.2 or more.
[0057]
Example 4
A slurry was obtained by dispersing 18.54 g of the spherical nickel hydroxide prepared in Example 1 in 0.1 L of water in a 1.0 L glass beaker. To this slurry, 61.2 mL of an aqueous cobalt nitrate solution (1.2 mol / L) and 6.8 mL of an aqueous iron nitrate solution (1.2 mol / L) were added in the presence of ammonium ions, and the beaker was sealed and stirred. Nitrogen gas was introduced into the slurry at a rate of 0.5 L / min to perform nitrogen substitution. After 30 minutes, an aqueous sodium hydroxide solution (0.44 mol / L) was added at a rate of 1.0 mL / min with a metering pump for 8 hours. The precipitate thus obtained was filtered, washed with water, and dried for one day at 60 ° C. in an electric dryer to obtain about 26 g of powder.
[0058]
X-ray diffraction analysis of the powder of nickel hydroxide (Ni (OH)₂) Was confirmed, and this powder consisted of substantially spherical particles according to observation with a scanning electron microscope. Further, when the cross section of the particle was subjected to a line analysis with an EPMA (electron probe microanalyzer), it was confirmed that nickel was localized in the center of the particle and cobalt and iron were unevenly distributed in the particle surface layer.
[0059]
From the above analysis results, the particles have a crystalline nickel hydroxide (Ni (OH)) at the center.₂), And the surface layer is amorphous cobalt hydroxide (Co (OH))₂) And ferrous hydroxide (Fe (OH)₂) To be substantially spherical particles.
[0060]
After 9.27 g of this powder was mixed with 4.2 g of lithium hydroxide monohydrate, it was placed in an alumina crucible and baked in an oxygen atmosphere at 700 ° C. for 10 hours to obtain a black powder. This powder has a lithium nickel composite oxide (LiNiO) at the center from X-ray diffraction, line analysis of cobalt, nickel and iron by EPMA, and scanning electron microscope observation.₂) And the surface layer portion is a lithium cobalt iron composite oxide (LiCo_0.9Fe_0.1O₂) Was confirmed to be a spherical particle having a two-layer structure. Furthermore, when the cobalt / (nickel + cobalt) atomic ratio from the particle surface to a depth of 0.1 μm was measured by Auger electron spectroscopy, it was 0.2 or more.
[0061]
Example 5
Primary particles are aggregated by adding and neutralizing an aqueous solution of sodium hydroxide in a nitrogen atmosphere in the presence of ammonium ions to an aqueous solution in which nickel nitrate and cobalt nitrate are mixed at a stoichiometric ratio of 85:15. As a result, secondary particle powder made of substantially spherical nickel cobalt hydroxide was obtained. This powder has a specific surface area of 160 m.₂/ G.
[0062]
A slurry was obtained by dispersing 18.54 g of this spherical nickel cobalt hydroxide in 0.1 L of water in a 1.0 L glass beaker. To this slurry was added 68.0 mL of an aqueous cobalt nitrate solution (1.2 mol / L) in the presence of ammonium ions, and after sealing the beaker, nitrogen gas was added to the slurry at a rate of 0.5 L / min while stirring. Introduced and replaced with nitrogen. After 30 minutes, an aqueous sodium hydroxide solution (0.44 mol / L) was added at a rate of 1.0 mL / min with a metering pump for 8 hours. The precipitate thus obtained was filtered, washed with water, and dried for one day at 60 ° C. in an electric dryer to obtain about 26 g of powder.
[0063]
When this powder was analyzed by X-ray diffraction, nickel cobalt hydroxide (Ni_0.85Co_0.15(OH)₂) Was confirmed, and this powder consisted of substantially spherical particles according to observation with a scanning electron microscope. Further, when the cross section of the particle was subjected to line analysis by EPMA (electron probe microanalyzer), it was confirmed that nickel and cobalt were unevenly distributed at the center of the particle and cobalt was unevenly distributed at the surface of the particle.
[0064]
From the above analysis results, the particles have a crystalline nickel cobalt hydroxide (Ni_0.85Co_0.15(OH)₂), And the surface layer is amorphous cobalt hydroxide (Co (OH))₂) To be substantially spherical particles.
[0065]
After 9.28 g of this powder was mixed with 4.2 g of lithium hydroxide monohydrate, it was placed in an alumina crucible and baked in an oxygen atmosphere at 700 ° C. for 10 hours to obtain a black powder. The center of this powder was lithium nickel cobalt composite oxide (LiNi) based on X-ray diffraction, line analysis of cobalt and nickel by EPMA, and observation with a scanning electron microscope._0.85Co_0.15O₂And the surface layer portion is a lithium cobalt composite oxide (LiCoO).₂) Was confirmed to be a spherical particle having a two-layer structure. Furthermore, when the cobalt / (nickel + cobalt) atomic ratio from the particle surface to a depth of 0.1 μm was measured by Auger electron spectroscopy, it was 0.2 or more.
[0066]
Example 6
A slurry was obtained by dispersing 18.54 g of the spherical nickel hydroxide powder prepared in Example 1 in 0.1 L of water in a 1.0 L glass beaker. To this slurry was added 50.0 mL of an aqueous cobalt nitrate solution (1.2 mol / L) in the presence of ammonium ions, and after sealing the beaker, nitrogen gas was added to the slurry at a rate of 0.5 L / min while stirring. Introduced and replaced with nitrogen. After 30 minutes, an aqueous sodium hydroxide solution (0.32 mol / L) was added at a rate of 1.0 mL / min with a metering pump for 8 hours. The precipitate thus obtained was filtered, washed with water, and dried for one day at 60 ° C. in an electric dryer to obtain about 24 g of powder.
[0067]
When this powder was analyzed by X-ray diffraction, nickel hydroxide (Ni (OH))₂) Was confirmed, and this powder consisted of substantially spherical particles according to observation with a scanning electron microscope. Further, when the cross section of the particle was analyzed by EPMA (electron probe microanalyzer), it was confirmed that nickel was unevenly distributed in the center of the particle and cobalt was unevenly distributed in the surface of the particle.
[0068]
From the above analysis results, the particles have a crystalline nickel hydroxide (Ni (OH)) at the center.₂), And the surface layer is amorphous cobalt hydroxide (Co (OH))₂) To be substantially spherical particles.
[0069]
After 9.28 g of this powder was mixed with 4.2 g of lithium hydroxide monohydrate, it was placed in an alumina crucible and baked in an oxygen atmosphere at 700 ° C. for 5 hours to obtain a black powder. The center of this powder was lithium nickel composite oxide (LiNiO) based on X-ray diffraction, line analysis of cobalt and nickel by EPMA, and observation with a scanning electron microscope.₂And the surface layer portion is a lithium cobalt composite oxide (LiCoO).₂) Was confirmed to be a spherical particle having a two-layer structure. Furthermore, when the cobalt / (nickel + cobalt) atomic ratio from the particle surface to a depth of 0.1 μm was measured by Auger electron spectroscopy, it was 0.2 or more.
[0070]
Example 7
A slurry was obtained by dispersing 18.54 g of the spherical nickel hydroxide prepared in Example 1 in 0.1 L of water in a 1.0 L glass beaker. To this slurry was added 50.0 mL of an aqueous cobalt nitrate solution (1.2 mol / L) in the presence of ammonium ions, and after sealing the beaker, nitrogen gas was added to the slurry at a rate of 0.5 L / min while stirring. Introduced and replaced with nitrogen. After 30 minutes, an aqueous sodium hydroxide solution (0.32 mol / L) was added at a rate of 1.0 mL / min with a metering pump for 8 hours. The precipitate thus obtained was filtered, washed with water, and dried for one day at 60 ° C. in an electric dryer to obtain about 24 g of powder.
[0071]
When this powder was analyzed by X-ray diffraction, nickel hydroxide (Ni (OH))₂) Was confirmed, and this powder consisted of substantially spherical particles according to observation with a scanning electron microscope. Further, when the cross section of the particle was analyzed by EPMA (electron probe microanalyzer), it was confirmed that nickel was unevenly distributed in the center of the particle and cobalt was unevenly distributed in the surface of the particle.
[0072]
From the above analysis results, the particles have a crystalline nickel hydroxide (Ni (OH)) at the center.₂), And the surface layer is amorphous cobalt hydroxide (Co (OH))₂) To be substantially spherical particles.
[0073]
24.1 g of this powder was oxidized with sodium persulfate in an aqueous slurry, then filtered and washed with water to obtain a nickel cobalt oxyhydroxide cake. 25.2 g of lithium hydroxide monohydrate was mixed with the total amount of this nickel cobalt oxyhydroxide, and ion-exchanged water was added to the resulting mixture to make the total amount 400 mL. The slurry was charged into an autoclave and heated at a temperature of 200 ° C. for 4 hours to perform hydrothermal treatment.
[0074]
After completion of the reaction, the slurry was filtered and washed with water, and the solid was heated to 100 ° C. and dried. The powder thus obtained was subjected to X-ray diffraction, line analysis of cobalt and nickel by EPMA, and observation by a scanning electron microscope.₂And the surface layer portion is a lithium cobalt composite oxide (LiCoO).₂) Was confirmed to be a spherical particle having a two-layer structure. Furthermore, when the cobalt / (nickel + cobalt) atomic ratio from the particle surface to a depth of 0.1 μm was measured by Auger electron spectroscopy, it was 0.2 or more.
[0075]
Example 8
18.54 g of the secondary particle powder made of substantially spherical nickel hydroxide obtained in Example 1 was dispersed in 0.1 L of water in a 1.0 L glass beaker to obtain a slurry. To this slurry, 17.0 mL of cobalt nitrate aqueous solution (1.2 mol / L) was added in the presence of ammonium ions, and after sealing the beaker, nitrogen gas was added to the slurry at a rate of 0.5 L / min while stirring. Introduced and replaced with nitrogen. After 30 minutes, an aqueous sodium hydroxide solution (0.11 mol / L) was added at a rate of 1.0 mL / min for 8 hours using a metering pump. The precipitate thus obtained was filtered, washed with water, and dried for one day at 60 ° C. in an electric dryer to obtain about 20 g of powder.
[0076]
After 9.38 g of this powder was mixed with 3.8 g of lithium hydroxide monohydrate, it was placed in an alumina crucible and baked in an oxygen atmosphere at 700 ° C. for 10 hours to obtain a black powder. From the X-ray diffraction, EPMA cobalt and nickel line analysis, and scanning electron microscope observation, this powder has a lithium nickel composite oxide (Li_0.90NiO₁.₉₅), And the surface layer portion is a lithium cobalt composite oxide (Li_0.90CoO_1.95) Was confirmed to be a spherical particle having a two-layer structure. Furthermore, when the cobalt / (nickel + cobalt) atomic ratio from the particle surface to a depth of 0.1 μm was measured by Auger electron spectroscopy, it was 0.2 or more.
[0077]
Example 9
18.54 g of the secondary particle powder made of substantially spherical nickel hydroxide obtained in Example 1 was dispersed in 0.1 L of water in a 1.0 L glass beaker to obtain a slurry. To this slurry, 17.0 mL of cobalt nitrate aqueous solution (1.2 mol / L) was added in the presence of ammonium ions, and after sealing the beaker, nitrogen gas was added to the slurry at a rate of 0.5 L / min while stirring. Introduced and replaced with nitrogen. After 30 minutes, an aqueous sodium hydroxide solution (0.11 mol / L) was added at a rate of 1.0 mL / min for 8 hours using a metering pump. The precipitate thus obtained was filtered, washed with water, and dried for one day at 60 ° C. in an electric dryer to obtain about 20 g of powder.
[0078]
After mixing 9.27 g of this powder with 4.6 g of lithium hydroxide monohydrate, it was placed in an alumina crucible and baked in an oxygen atmosphere at 700 ° C. for 10 hours to obtain a black powder. From the X-ray diffraction, EPMA cobalt and nickel line analysis, and scanning electron microscope observation, this powder has a lithium nickel composite oxide (Li_1.1NiO_2.05), And the surface layer portion is a lithium cobalt composite oxide (Li_1.1CoO_2.05) Was confirmed to be a spherical particle having a two-layer structure. Furthermore, when the cobalt / (nickel + cobalt) atomic ratio from the particle surface to a depth of 0.1 μm was measured by Auger electron spectroscopy, it was 0.2 or more.
[0079]
Example 10
18.54 g of the secondary particle powder made of substantially spherical nickel hydroxide obtained in Example 1 was dispersed in 0.1 L of water in a 1.0 L glass beaker to obtain a slurry. To this slurry, 15.8 mL of cobalt nitrate aqueous solution (1.2 mol / L) and 1.0 mL of copper nitrate aqueous solution (1.0 mol / L) were added in the presence of ammonium ions, and the beaker was sealed and stirred. However, nitrogen gas was introduced into the slurry at a rate of 0.5 L / min to perform nitrogen substitution. After 30 minutes, an aqueous sodium hydroxide solution (0.11 mol / L) was added at a rate of 1.0 mL / min for 8 hours using a metering pump. The precipitate thus obtained was filtered, washed with water, and dried for one day at 60 ° C. in an electric dryer to obtain about 20 g of powder.
[0080]
After 9.27 g of this powder was mixed with 4.2 g of lithium hydroxide monohydrate, it was placed in an alumina crucible and baked in an oxygen atmosphere at 800 ° C. for 10 hours to obtain a black powder. The center of this powder was lithium nickel composite oxide (LiNiO) based on X-ray diffraction, line analysis of cobalt and nickel by EPMA, and observation with a scanning electron microscope.₂The surface layer portion is a lithium cobalt composite oxide (LiCo_0.95Cu_0.05O₂) Was confirmed to be a spherical particle having a two-layer structure. Furthermore, when the cobalt / (nickel + cobalt) atomic ratio from the particle surface to a depth of 0.1 μm was measured by Auger electron spectroscopy, it was 0.2 or more.
[0081]
Example 11
18.54 g of the secondary particle powder made of substantially spherical nickel hydroxide obtained in Example 1 was dispersed in 0.1 L of water in a 1.0 L glass beaker to obtain a slurry. To this slurry, 15.0 mL of an aqueous cobalt nitrate solution (1.2 mol / L) and 2.0 mL of an aqueous magnesium nitrate solution (1.0 mol / L) were added in the presence of ammonium ions, and the beaker was sealed and stirred. However, nitrogen gas was introduced into the slurry at a rate of 0.5 L / min to perform nitrogen substitution. After 30 minutes, an aqueous sodium hydroxide solution (0.11 mol / L) was added at a rate of 1.0 mL / min for 8 hours using a metering pump. The precipitate thus obtained was filtered, washed with water, and dried for one day at 60 ° C. in an electric dryer to obtain about 20 g of powder.
[0082]
After 9.24 g of this powder was mixed with 4.2 g of lithium hydroxide monohydrate, it was placed in an alumina crucible and baked in an oxygen atmosphere at 800 ° C. for 10 hours to obtain a black powder. The center of this powder was lithium nickel composite oxide (LiNiO) based on X-ray diffraction, line analysis of cobalt and nickel by EPMA, and observation with a scanning electron microscope.₂The surface layer portion is a lithium cobalt composite oxide (LiCo_0.90Mg_0.10O_1.95) Was confirmed to be a spherical particle having a two-layer structure. Furthermore, when the cobalt / (nickel + cobalt) atomic ratio from the particle surface to a depth of 0.1 μm was measured by Auger electron spectroscopy, it was 0.2 or more.
[0083]
Example 12
18.54 g of the secondary particle powder made of substantially spherical nickel hydroxide obtained in Example 1 was dispersed in 0.1 L of water in a 1.0 L glass beaker to obtain a slurry. To this slurry, 15.8 mL of a cobalt nitrate aqueous solution (1.2 mol / L) and 1.0 mL of an aluminum nitrate aqueous solution (1.0 mol / L) were added in the presence of ammonium ions, and the beaker was sealed and stirred. However, nitrogen gas was introduced into the slurry at a rate of 0.5 L / min to perform nitrogen substitution. After 30 minutes, an aqueous sodium hydroxide solution (0.11 mol / L) was added at a rate of 1.0 mL / min for 8 hours using a metering pump. The precipitate thus obtained was filtered, washed with water, and dried for one day at 60 ° C. in an electric dryer to obtain about 20 g of powder.
[0084]
After 9.27 g of this powder was mixed with 4.2 g of lithium hydroxide monohydrate, it was placed in an alumina crucible and baked in an oxygen atmosphere at 800 ° C. for 10 hours to obtain a black powder. The center of this powder was lithium nickel composite oxide (LiNiO) based on X-ray diffraction, line analysis of cobalt and nickel by EPMA, and observation with a scanning electron microscope.₂The surface layer portion is a lithium cobalt composite oxide (LiCo_0.95Al_0.05O₂) Was confirmed to be a spherical particle having a two-layer structure. Furthermore, when the cobalt / (nickel + cobalt) atomic ratio from the particle surface to a depth of 0.1 μm was measured by Auger electron spectroscopy, it was 0.2 or more.
[0085]
Example 13
18.54 g of the secondary particle powder made of substantially spherical nickel hydroxide obtained in Example 1 was dispersed in 0.1 L of water in a 1.0 L glass beaker to obtain a slurry. To this slurry, 13.3 mL of cobalt nitrate aqueous solution (1.2 mol / L) and 4.0 mL of titanium nitrate aqueous solution (1.0 mol / L) were added in the presence of ammonium ions, and the beaker was sealed and stirred. However, nitrogen gas was introduced into the slurry at a rate of 0.5 L / min to perform nitrogen substitution. After 30 minutes, an aqueous sodium hydroxide solution (0.13 mol / L) was added at a rate of 1.0 mL / min for 8 hours using a metering pump. The precipitate thus obtained was filtered, washed with water, and dried for one day at 60 ° C. in an electric dryer to obtain about 20 g of powder.
[0086]
After mixing lithium hydroxide monohydrate 4.2g with this powder 9.31g, it put into the crucible made from an alumina, and baked at 800 degreeC in oxygen atmosphere for 10 hours, and obtained black powder. The center of this powder was lithium nickel composite oxide (LiNiO) based on X-ray diffraction, line analysis of cobalt and nickel by EPMA, and observation with a scanning electron microscope.₂The surface layer portion is a lithium cobalt composite oxide (LiCo_0.80Ti_0.20O_2.1) Was confirmed to be a spherical particle having a two-layer structure. Furthermore, when the cobalt / (nickel + cobalt) atomic ratio from the particle surface to a depth of 0.1 μm was measured by Auger electron spectroscopy, it was 0.2 or more.
[0087]
Example 14
Primary particles were assembled by adding and neutralizing an aqueous solution of sodium hydroxide continuously in a nitrogen atmosphere in the presence of ammonium ions to an aqueous solution in which nickel nitrate and vanadium nitrate were mixed at a stoichiometric ratio of 85:15. A secondary particle powder consisting of substantially spherical nickel hydroxide-vanadium was obtained. This powder has a specific surface area of 150 m.²/ G.
[0088]
A slurry was obtained by dispersing 18.31 g of the secondary particle powder made of spherical nickel hydroxide-vanadium in 0.1 L of water in a 1.0 L glass beaker. To this slurry, 66.7 mL of an aqueous cobalt nitrate solution (1.2 mol / L) was added in the presence of ammonium ions. After sealing the beaker, nitrogen gas was added to the slurry at a rate of 0.5 L / min while stirring. Introduced and replaced with nitrogen. After 30 minutes, an aqueous sodium hydroxide solution (0.43 mol / L) was added at a rate of 1.0 mL / min for 8 hours using a metering pump. The precipitate thus obtained was filtered, washed with water, and dried for one day at 60 ° C. in an electric dryer to obtain about 25 g of powder.
[0089]
After 9.20 g of this powder was mixed with 4.2 g of lithium hydroxide monohydrate, it was placed in an alumina crucible and baked at 800 ° C. for 10 hours in an oxygen atmosphere to obtain a black powder. This powder has a lithium nickel vanadium complex oxide (LiNi) at the center from X-ray diffraction, line analysis of cobalt, nickel and vanadium by EPMA, and observation by a scanning electron microscope._0.85V_0.15O_2.15And the surface layer portion is a lithium cobalt composite oxide (LiCoO).₂) Was confirmed to be a spherical particle having a two-layer structure. Furthermore, when the cobalt / (nickel + cobalt) atomic ratio from the particle surface to a depth of 0.1 μm was measured by Auger electron spectroscopy, it was 0.2 or more.
[0090]
Example 15
Primary particles were assembled by adding and neutralizing an aqueous solution of sodium hydroxide in a nitrogen atmosphere in the presence of ammonium ions in a nitrogen atmosphere in which nickel nitrate and chromium nitrate were mixed at a stoichiometric ratio of 85:15. Secondary particle powder consisting of substantially spherical nickel hydroxide-chromium was obtained. This powder has a specific surface area of 156 m.²/ G.
[0091]
A slurry was obtained by dispersing 18.24 g of the above-mentioned spherical nickel hydroxide-chromium secondary particle powder in 0.1 L of water in a 1.0 L glass beaker. To this slurry, 66.7 mL of an aqueous cobalt nitrate solution (1.2 mol / L) was added in the presence of ammonium ions. After sealing the beaker, nitrogen gas was added to the slurry at a rate of 0.5 L / min while stirring. Introduced and replaced with nitrogen. After 30 minutes, an aqueous sodium hydroxide solution (0.43 mol / L) was added at a rate of 1.0 mL / min for 8 hours using a metering pump. The precipitate thus obtained was filtered, washed with water, and dried for one day at 60 ° C. in an electric dryer to obtain about 25 g of powder.
[0092]
After 9.21 g of this powder was mixed with 4.2 g of lithium hydroxide monohydrate, it was placed in an alumina crucible and baked at 800 ° C. for 10 hours in an oxygen atmosphere to obtain a black powder. This powder has a lithium nickel chromium composite oxide (LiNi) at the center from X-ray diffraction, line analysis of cobalt, nickel and chromium by EPMA, and observation by a scanning electron microscope._0.85Cr_0.15O₂And the surface layer portion is a lithium cobalt composite oxide (LiCoO).₂) Was confirmed to be a spherical particle having a two-layer structure. Furthermore, when the cobalt / (nickel + cobalt) atomic ratio from the particle surface to a depth of 0.1 μm was measured by Auger electron spectroscopy, it was 0.2 or more.
[0093]
Example 16
Primary particles were aggregated by adding and neutralizing an aqueous solution of sodium hydroxide in a nitrogen atmosphere in the presence of ammonium ions and neutralizing it in an aqueous solution in which nickel nitrate and manganese nitrate were mixed at a stoichiometric ratio of 85:15. A secondary particle powder consisting of substantially spherical nickel hydroxide-manganese was obtained. This powder has a specific surface area of 145 m.²/ G.
[0094]
A slurry was obtained by dispersing 18.43 g of the above-mentioned spherical nickel hydroxide-manganese secondary particle powder in 0.1 L of water in a 1.0 L glass beaker. To this slurry, 66.7 mL of an aqueous cobalt nitrate solution (1.2 mol / L) was added in the presence of ammonium ions. After sealing the beaker, nitrogen gas was added to the slurry at a rate of 0.5 L / min while stirring. Introduced and replaced with nitrogen. After 30 minutes, an aqueous sodium hydroxide solution (0.43 mol / L) was added at a rate of 1.0 mL / min for 8 hours using a metering pump. The precipitate thus obtained was filtered, washed with water, and dried for one day at 60 ° C. in an electric dryer to obtain about 25 g of powder.
[0095]
After 9.24 g of this powder was mixed with 4.2 g of lithium hydroxide monohydrate, it was placed in an alumina crucible and baked in an oxygen atmosphere at 800 ° C. for 10 hours to obtain a black powder. This powder is based on X-ray diffraction, line analysis of cobalt, nickel and manganese by EPMA, and observation by scanning electron microscope._0.85Mn_0.15O₂And the surface layer portion is a lithium cobalt composite oxide (LiCoO).₂) Was confirmed to be a spherical particle having a two-layer structure. Furthermore, when the cobalt / (nickel + cobalt) atomic ratio from the particle surface to a depth of 0.1 μm was measured by Auger electron spectroscopy, it was 0.2 or more.
[0096]
Example 17
Primary particles were aggregated by adding and neutralizing an aqueous solution of sodium hydroxide and an aqueous solution of nickel nitrate and lanthanum nitrate in a stoichiometric ratio of 85:15 in the presence of ammonium ions in a nitrogen atmosphere. A secondary particle powder consisting of substantially spherical nickel lanthanum hydroxide was obtained. This powder has a specific surface area of 170 m.²/ G.
[0097]
A slurry was obtained by dispersing 21.46 g of the above-mentioned spherical nickel hydroxide lanthanum powder in 0.1 L of water in a 1.0 L glass beaker. To this slurry, 66.7 mL of an aqueous cobalt nitrate solution (1.2 mol / L) was added in the presence of ammonium ions. After sealing the beaker, nitrogen gas was added to the slurry at a rate of 0.5 L / min while stirring. Introduced and replaced with nitrogen. After 30 minutes, an aqueous sodium hydroxide solution (0.43 mol / L) was added at a rate of 1.0 mL / min for 8 hours using a metering pump. The precipitate thus obtained was filtered, washed with water, and dried for one day at 60 ° C. in an electric dryer to obtain about 28 g of powder.
[0098]
14.45 g of this powder was mixed with 4.2 g of lithium hydroxide monohydrate, then placed in an alumina crucible and baked in an oxygen atmosphere at 800 ° C. for 10 hours to obtain a black powder. This powder is based on X-ray diffraction, line analysis of cobalt, nickel and lanthanum by EPMA, and observation with a scanning electron microscope._0.85La_0.15O₂And the surface layer portion is a lithium cobalt composite oxide (LiCoO).₂) Was confirmed to be a spherical particle having a two-layer structure. Furthermore, when the cobalt / (nickel + cobalt) atomic ratio from the particle surface to a depth of 0.1 μm was measured by Auger electron spectroscopy, it was 0.2 or more.
[0099]
Example 18
Primary particles were assembled by adding and neutralizing an aqueous solution of sodium hydroxide continuously in a nitrogen atmosphere in the presence of ammonium ions to an aqueous solution in which nickel nitrate and gallium nitrate were mixed at a stoichiometric ratio of 85:15. A secondary particle powder made of substantially spherical nickel gallium hydroxide was obtained. This powder has a specific surface area of 150 m.²/ G.
[0100]
A slurry was obtained by dispersing 19.38 g of the above secondary particle powder made of spherical nickel gallium hydroxide in 0.1 L of water in a 1.0 L glass beaker. To this slurry, in the presence of ammonium ions, 14.2 mL of cobalt nitrate aqueous solution (1.2 mol / L) and 3.0 mL of nickel nitrate aqueous solution (1.0 mol / L) were added, and the beaker was sealed and stirred. However, nitrogen gas was introduced into the slurry at a rate of 0.5 L / min to perform nitrogen substitution. After 30 minutes, an aqueous sodium hydroxide solution (0.11 mol / L) was added at a rate of 1.0 mL / min for 8 hours using a metering pump. The precipitate thus obtained was filtered, washed with water, and dried for one day at 60 ° C. in an electric dryer to obtain about 21 g of powder.
[0101]
After 9.65 g of this powder was mixed with 4.2 g of lithium hydroxide monohydrate, it was placed in an alumina crucible and baked in an oxygen atmosphere at 800 ° C. for 10 hours to obtain a black powder. This powder has a lithium nickel gallium complex oxide (LiNi) at the center from X-ray diffraction, line analysis of cobalt, nickel and gallium by EPMA, and observation by a scanning electron microscope._0.85Ga_0.15O₂And the surface layer portion is a lithium cobalt nickel composite oxide (LiCo_0.85Ni_0.15O₂) Was confirmed to be a spherical particle having a two-layer structure. Furthermore, when the cobalt / (nickel + cobalt) atomic ratio from the particle surface to a depth of 0.1 μm was measured by Auger electron spectroscopy, it was 0.2 or more.
[0102]
Example 19
To an aqueous solution in which nickel nitrate, cobalt nitrate and iron nitrate are mixed at a stoichiometric ratio of 80: 15: 5, an aqueous solution of sodium hydroxide is continuously added and neutralized in a nitrogen atmosphere in the presence of ammonium ions. A secondary particle powder made of substantially spherical nickel cobalt iron hydroxide in which primary particles were aggregated was obtained. This powder has a specific surface area of 160 m.²/ G.
[0103]
A slurry was obtained by dispersing 18.52 g of the secondary particle powder made of spherical nickel cobalt iron hydroxide in 0.1 L of water in a 1.0 L glass beaker. In this slurry, in the presence of ammonium ions, 15.0 mL of an aqueous cobalt nitrate solution (1.2 mol / L), 1.0 mL of an aqueous zirconium nitrate solution (1.0 mol / L), and an aqueous yttrium nitrate solution (1.0 mol / L) After adding 1.0 mL and sealing the beaker, nitrogen gas was introduced into the slurry at a rate of 0.5 L / min while stirring to perform nitrogen substitution. After 30 minutes, an aqueous sodium hydroxide solution (0.11 mol / L) was added at a rate of 1.0 mL / min for 8 hours using a metering pump. The precipitate thus obtained was filtered, washed with water, and dried for one day at 60 ° C. in an electric dryer to obtain about 20 g of powder.
[0104]
After mixing lithium hydroxide monohydrate 4.2g with this powder 9.31g, it put into the crucible made from an alumina, and baked at 800 degreeC in oxygen atmosphere for 10 hours, and obtained black powder. From the X-ray diffraction, EPMA line analysis, and scanning electron microscope observation, this powder has a lithium nickel cobalt iron composite oxide (LiNi_0.85Co_0.15Fe_0.05O₂) And the surface layer portion is lithium cobalt zirconium yttrium composite oxide (LiCo_0.90Zr_0.05Y_0.05O_2.025) Was confirmed to be a spherical particle having a two-layer structure. Furthermore, when the cobalt / (nickel + cobalt) atomic ratio from the particle surface to a depth of 0.1 μm was measured by Auger electron spectroscopy, it was 0.2 or more.
[0105]
[Table 1]

[0106]
[Table 2]

[0107]
Example 20
The central part prepared in Example 2 is a lithium nickel composite oxide (LiNiO₂And the surface layer portion is a lithium cobalt composite oxide (LiCoO).₂) Powder (positive electrode active material), acetylene black (conductive agent) and polytetrafluoroethylene (binder) in a weight ratio of 87: 6.5: 6.5. Thus, a mixture was prepared. This mixture was uniformly applied to a clean stainless steel mesh (hole diameter: 20 mm) as a positive electrode current collector, 200 kg / cm²After press-bonding at a pressure of 1, a positive electrode was produced by drying at 150 ° C. under reduced pressure for 17 hours. A disk-shaped metal lithium foil (diameter 20 mm, thickness 0.2 mm) was used as the negative electrode. In addition, a porous film made of polypropylene was used as a separator.
[0108]
The non-aqueous electrolyte is lithium perchlorate (LiClO).₄) Of propylene carbonate solution (1M) and 1,2-dimethoxyethane (1: 1) having a water content of 20 ppm or less was impregnated into the separator.
Using these components, a lithium ion secondary battery as shown in FIG. 1 is manufactured, and using this, the current value is 1.0 mA / cm.²The battery characteristics were examined by repeating charge and discharge at a battery voltage of 4.2 to 2.0 V. As a result, the initial capacity of the lithium secondary battery according to the present invention is as high as 182 mAh / g, and the charge / discharge capacity at the 50th cycle is 90% at the first cycle, which is excellent in cycle characteristics.
[0109]
In addition, when this battery is held at 80 ° C. for a long time, the electrolyte solution is lithium cobalt composite oxide (LiCoO₂) Was the same as when the positive electrode active material was used, and it was confirmed that it was hardly decomposed and had excellent stability at high temperatures.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an example of a lithium ion secondary battery.
2 is a scanning electron micrograph (magnification 500 times) of the nickel hydroxide secondary particle powder obtained in Example 1. FIG.
FIG. 3 is an X-ray diffraction diagram of nickel cobalt hydroxide formed by coating the nickel hydroxide particles with cobalt hydroxide.
FIG. 4 is a scanning electron micrograph (magnification 500 times) of the nickel cobalt hydroxide.
FIG. 5 is a photograph (magnification 1000 times) showing a line analysis by EPMA (electron probe microanalyzer) of the cross section of the nickel cobalt hydroxide particles.
FIG. 6 shows that the central part obtained in Example 1 is lithium nickelate (LiNiO).₂And the surface layer portion is lithium cobalt oxide (LiCoO).₂Is a photograph (magnification 1000 times) showing a line analysis by EPMA (electron beam probe microanalyzer) of a cross section of a spherical particle having a two-layer structure.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Positive electrode, 2 ... Negative electrode, 3 ... Separator, 4 ... Battery container, 5 ... Positive electrode collector, 6 ... Positive electrode lead wire, 7 ... Negative electrode collector, 8 ... Negative electrode lead wire.

Claims (5)

  In a slurry of nickel hydroxide powder dispersed in water, cobalt hydroxide aqueous solution and caustic alkaline aqueous solution are continuously added and reacted in the presence of ammonium ions, thereby reacting cobalt hydroxide on the surface of nickel hydroxide particles. A coated particle is prepared, mixed with lithium hydroxide, and calcined, and provided with a central layer made of a lithium nickel composite oxide and a surface layer made of a lithium cobalt composite oxide. The manufacturing method of the two-layer structure particulate composition for positive electrode active materials for lithium ion secondary batteries whose cobalt / (nickel + cobalt) atomic ratio to the depth of 0.1 micrometer from the surface is the range of 0.2-1.   In a slurry of nickel hydroxide powder dispersed in water, cobalt hydroxide aqueous solution and caustic alkaline aqueous solution are continuously added and reacted in the presence of ammonium ions, thereby reacting cobalt hydroxide on the surface of nickel hydroxide particles. Lithium-nickel composite oxide comprising preparing coated particles, oxidizing them to prepare hydrous nickel-cobalt, and then performing hydrothermal reaction with lithium hydroxide in an aqueous dispersion medium And a lithium ion having a cobalt / (nickel + cobalt) atomic ratio in the range of 0.2 to 1 from the particle surface to a depth of 0.1 μm. The manufacturing method of the two-layer structure particulate composition for positive electrode active materials for secondary batteries. The central layer is the general formula (I)
_{Li p Ni 1-x A x} O y
(In the formula, A is B, Mg, Al, Si, Sc, Ti, V, Cr, Mn, Fe, Co, Cu, Zn, Ga, Y, Zr, Nb, Mo, Ru, Sn, Sb, La. And at least one element selected from the group consisting of Ce, Pr, Nb, Hf, Ta and Pb, p is a number in the range of 0.90 to 1.10, and x is 0 to 0.25. The number of ranges is shown, y shows the number of the range of 1.825-2.3.) Production of the two-layer structure particulate composition of Claim 1 or 2 which consists of lithium nickel complex oxide represented by these Method. Surface layer is general formula (II)
Li _q Co _1-a Z _a O _b
(In the formula, Z is B, Mg, Al, Si, Sc, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Ga, Y, Zr, Nb, Mo, Ru, Sn, Sb, La. , Ce, Pr, Nd, Hf, Ta and Pb, at least one element selected from the group consisting of q, q represents a number in the range of 0.90 to 1.10, and a is 0 to 0.25. indicates the number of ranges, b is two-layer structure particle according to claim 1 or 2, characterized in that a lithium cobalt composite oxide represented by the indicating.) the number in the range of 1.825 to 2.3 A method for producing a composition. The method for producing a two-layered particulate composition according to any one of claims 1 to 4 , wherein the average particle size is 3 to 100 µm and the shape is substantially spherical.

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