JP2006515950A - Active nickel mixed hydroxide-cathode material for alkaline storage battery and method for producing the same - Google Patents

Abstract

Active nickel mixed hydroxide-cathode materials for use in alkaline storage batteries have a special bimodal particle size distribution, which achieves good properties of nickel mixed hydroxide-cathode materials. The The production of the nickel mixture hydroxide material is particularly advantageously carried out in a continuous precipitation process in a loop reactor with an integrated purification zone.

Description

  The present invention relates to an active nickel mixed hydroxide-cathode material for an alkaline storage battery and a method for producing the same. More precisely, the present invention relates to a nickel mixed hydroxide material containing a defined amount and size of a main population and a subpopulation, and a method whereby a multimodal nickel mixed hydride is obtained in the process steps.

Prior Art Nickel mixed hydroxide electrodes containing mainly nickel hydroxide as an active material are used as positive electrodes in nickel cadmium (NiCd) and nickel metal hydroxide (NiMH) batteries. In particular, from the viewpoint of using such a storage battery in a portable electric device or vehicle, an increase in the demand for improving the capacity of the storage battery requires an improvement in the energy density of the storage battery used. The energy density of the storage battery depends mainly on the quality of the nickel mixed hydroxide material used for the production of the positive electrode. A material with a high electrochemical capacity and a high tap density is particularly advantageous.

  In order to improve the properties of the nickel mixed hydroxide-cathode material, there are a variety of approaches regarding the composition and manufacturing method of this material.

Publication EP 0353837 B1 describes a basic process for the production of nickel-mixed hydroxides by a combination of nickel (II) salt solution, ammonium source and hydroxide source. A nickel electrode having a nickel hydroxide powder with zinc or magnesium in the form of a solid solution in the crystal of nickel hydroxide is obtained, wherein zinc or magnesium is in the range of 3-10% by mass or 1-3% by mass. And the pore size in the powder is not larger than 3 nm as a radius and the pore volume is smaller than 0.05 cm ³ / g. This material is produced by precipitation of nickel hydroxide crystals containing a small amount of zinc or magnesium from an aqueous solution of ammonium sulfate, followed by the addition of sodium hydroxide or potassium hydroxide to a pH value. Is set to 11-13.

From the publication JP 3252318, a process for the production of spherical nickel hydroxide particles which can contain cobalt or cadmium is known. For this purpose, a) a nickel salt aqueous solution or an aqueous solution containing nickel salt, cobalt salt and cadmium salt continuously in the reactor,
b) An aqueous solution of an alkali metal hydroxide and c) nickel hydroxide particles or nickel hydroxide particles containing cobalt or cadmium filled with an ammonium ion donor. This reaction is facilitated by maintaining the temperature at a level of 20-80 ° C., maintaining the pH value at a predetermined value in the range of 9-12, and continuously removing the product. This reaction is suitable for the preference of a particular particle size by adjusting certain conditions. In order to obtain the desired particle size distribution in the cathode material, two mixed hydroxides, each produced under different conditions, each having a relatively narrow particle size distribution, are mixed in a predetermined ratio in a further processing step. As can be appreciated in particular from the drawing, the optimal distribution of the different sized particles of the mixed hydroxide is not achieved by subsequent mixing.

  Active nickel hydroxide powders for use in producing positive nickel electrodes are also described in publication EP 0523284 B1. Prior to the production of the positive electrode, the powder is a mixture of spherical and nearly spherical particles and non-spherical particles, which are cadmium, calcium, zinc, magnesium, iron, cobalt; manganese; A nickel hydroxide powder having 1 to 7% by mass of at least one component selected from the group consisting of cobalt, zinc oxide and cadmium oxide is included. This powder is obtained from an aqueous solution of a nickel salt and at least one selected component by adjusting the reaction pH to 11.3 ± 0.2 and the reaction temperature to 30-40 ° C.

Publication EP 0658514 B1 describes the continuous production of sparingly soluble metal hydroxides of the general formula M ^(x) (OH) _x , where M = Co, Zn, Ni or Cu and x represents the valence of the metal. Describes the method. In the first step, the metal hydroxide obtained by anodic oxidation of the metal is converted to a metal complex salt of the general formula ML _n Y _m and an alkali liquid in the presence of the complexing agent L and the alkali metal salt AY, and> 7 At a pH value of 1 to 30, the complexing agent L and the alkali metal salt AY are returned to the first step, and the decomposition of the metal complex salt is This is carried out using the alkaline liquid produced in the first step.

  Scherzberg et.al .; Chemie Ingenieur Technik 70 12/1998 p. 1530-1535 is a process for the production of lumped monomodal hydroxides characterized by a narrow-band size distribution, such as magnesium hydroxide and nickel hydroxide. Is described. Using the apparatus described herein, spherical metal hydroxides with a narrow particle size distribution can be produced.

  An object of the present invention is to provide an electrochemically high loadable nickel mixed hydroxide having a high electrochemical capacity, low self-discharge properties and a sufficiently high tap density and a high BET surface area.

DISCLOSURE OF THE INVENTION Accordingly, the present invention provides that the nickel mixed hydroxide-cathode material according to the present invention for use in alkaline storage batteries has a bimodal, mass-based particle size distribution, wherein the mass of the main population The median of the particle size distribution based on is from 5 μm to 25 μm, the median of the particle size distribution based on the mass of the subpopulation is from 0.3 μm to 3 μm, and the proportion based on the mass of the main population is from 70 to 96%.

  The nickel mixed hydroxide-cathode material itself according to the present invention has been found to exhibit high crystal order defects, as a measure, the half-width of 101 and 102 reflections in X-ray diffraction analysis, and a sufficiently high tap density.

Too high ordering in the crystal results in non-optimal electrochemical properties such as a small capacity. However, up to now, the improvement of ordered defects in the crystal deteriorates the mechanical properties, for example, lowers the tap density below 1.5 g / m ³ , deteriorates the filterability, and expands the width of the particle size distribution. have done. The above disadvantages can be overcome by the provision of a nickel mixed hydroxide-cathode material characterized by having a main group and a sub-group of two defined groups.

  In other words, this problem is solved by producing a precipitation product that can be represented as a nickel mixed hydroxide that consists of a main population and subpopulations and is distributed in a bimodal manner with respect to the distribution on the particle size based on mass. Thereby, the width of the main group can be kept narrow. What is important for this distribution is that the average particle size of the subpopulation compared to the main population is so small that the type of subpopulation fills the voids of the main population with close packing. Thereby, the reduction in tap density associated with this reduction in ordering can be guaranteed or mitigated. In the case of a bimodal distribution, of course, a higher space filling is achieved than in the case of a unimodal distribution. In addition, many contact points are created between the individual particles, which has an advantageous effect on the capacity loading characteristics and on large BET surfaces.

  The median particle size distribution based on mass is derived from the particle size based on the volume of the nickel mixed hydroxide according to the present invention measured using laser particle analysis and is shown in FIGS. Various test times are given for mixed hydroxides. Conversion from a volume-based particle size distribution to a mass-based particle size distribution can be done by the following formula:

（式中、ｍi＝粒子クラスｉの質量割合、ρi＝粒子クラスｉの粒子の密度、ρ＝ニッケル混合水酸化物の純粋な密度、Ｖi＝粒子クラスｉの体積割合）。走査顕微鏡による検査に基づき及びエネルギー分散型Ｘ線微量分析装置に基づき、粒度に依存しない材料組成及び
ρi＝ρ＝３．５６ｇ／ｃｍ^３
を有する材料密度が導き出され、その結果、本発明によるニッケル混合水酸化物の質量に基づく粒度分布は体積に基づく粒度分布と同一である。

(Where, mi = mass fraction of particle class i, ρi = density of particles of particle class i, ρ = pure density of nickel mixed hydroxide, Vi = volume fraction of particle class i). Based on inspection with a scanning microscope and on an energy dispersive X-ray microanalyzer, material composition independent of particle size and ρi = ρ = 3.56 g / cm ³
The resulting material density is as follows, so that the particle size distribution based on the mass of the nickel mixed hydroxide according to the invention is identical to the particle size distribution based on volume.

  In a preferred embodiment of the invention, the median of the main population of particles is 6-12 μm and the median of the subpopulation is 0.3-1.5 μm. In other embodiments, a mass proportion of the main population of 70 to 95% by weight is particularly advantageous.

  The mixed hydroxide is generally interpreted as a hydroxide having various cations. Nickel mixed hydroxide is a mixture containing mainly nickel (II) ions as cations and a small amount of other cations in order to influence the physicochemical and especially electrical properties. Interpreted as a hydroxide.

  The nickel mixed hydroxide-cathode material according to the invention advantageously consists of nickel for cations and additionally at least one component consisting of the group magnesium, calcium, zinc, cobalt, aluminum, manganese, iron, chromium, rare earths. It is advantageous to be configured as such.

  Furthermore, the mixed hydroxide can have a monovalent or divalent anion consisting of chloride, nitrate, and sulfate. This may be incorporated into the nickel hydroxide crystal structure, for example other divalent and trivalent cations present in minor amounts.

Advantageously, the nickel proportion of the nickel mixed hydroxide-cathode material is 40-60% by weight, more preferably 55-59% by weight, based on the dry weight. The specific surface area of the mixed hydroxide according to the invention, measured respectively as BET value is 10 to 100 m ² / g, preferably 15~40m ² / g.

  The improved properties of the nickel mixed hydroxide material are achieved by having the material have a predetermined bimodal particle size distribution.

A powder having a bimodal particle size distribution exhibits a higher packing density compared to a powder having a corresponding monomodal particle size distribution and having the same density and morphology at the appropriate sphere diameter ratio. Furthermore, the internal surface area of the material as well as the number of contact points per unit volume are increased. The density of the resulting material significantly lower ^{Nevertheless,} it is possible to achieve a tap density of ^{1.8g / cm 3 ~2.0g / cm 3} . The electrochemical capacity increases to above 260 mAh / g. This material rapidly deposited is well possible and washable ^filtration, has a very high BET surface area of 20m ² / g~40m 2 / g. This material consists of round agglomerates of amorphous spherical primary particles, which consist of crystallites with a size of 100-200 nm arranged on a mosaic. Furthermore, the advantageous electrochemical properties of the material according to the invention, for example high loadability, likewise arise from the above-described bimodal distribution.

The essence of the effect of the present invention is that the appropriate sphere diameter ratio of the population is associated with an appropriate mass ratio between these populations that has not been established in the prior art. For example, the width between the percentiles D _90% and D _10% of the particle size distribution based on the mass of the main and subpopulations does not overlap. This percentile shows in this case the x value, where the distribution sum for the variable x reaches a corresponding percentage of the overall distribution.

  The production of the nickel mixed hydroxide-material according to the invention can be carried out by precipitation in a loop reactor equipped with an integrated purification zone and will be described individually below. With an integrated purification zone, the average residence time of the solids in the reactor can be selected independently of the residence time of the reaction solution.

The production of the cathode material according to the invention with a bimodal particle size distribution in a loop reactor with an integrated purification zone makes it simple that the material from such a precipitation process is usually very consistent. It was also surprising because it is known to be characterized by a peak, on the other hand, an extremely narrow band size distribution (Scherzberg et. Al. (1998) Scherzberg, H.; Kahle, K.; Kaeseberg, K .; Chemie Ingenieur Technik 7012/1998 p. 1530-1535). The width of the distribution based on the average particle size and the mass of the particle size depends on the magnitude of the series of physical and chemical influences, which are material specific and method specific. Nickel hydroxides produced by the method described by Scherzberg et al exhibit a structure that grows in the radial direction of the particles and a narrow band size distribution. Based on the selected conditions, the precipitated material grows into spherical particles in a very compact form. The particles tend to accumulate rapidly, with excellent filtration properties and very good cleaning. The BET surface area of this material is generally about 10 m ² / g with a tap density of> 2.1 g / cm ³ . However, the electrochemical capacity of this material is between 220 mAh / g and 240 mAh / g, clearly below other known materials.

  Surprisingly, during the precipitation of the nickel-mixed hydroxide, the state can be stabilized in time with appropriate parameter adjustments, in which case a second population with a clearly low average particle size is obtained. , Which occurs at a constant time ratio with respect to the coarse-grained main population, in this case about 5-30% of the total mass. This proportion is particularly important for the advantageous properties of the material, just as described above.

  During the parameter adjustment according to the invention of the above process, a so-called oscillation phenomenon occurs, in which the average particle size first increases continuously and the number of crystal nuclei is the second of particles having a significantly lower particle size. Gradually decline until a population occurs. This population continues to increase continuously both in terms of mass and in terms of particle size. The desired material is produced with an experimentally measured time window.

  A possible production method for the nickel mixed hydroxide-cathode material according to the present invention, which could not be produced using known precipitation methods so far, is suitable for adjusting the oscillation phenomenon in the reactor with respect to particle size by adjusting the parameters. It is to cause. Thereby, the synchronous mixing of the precipitate consisting of the finest primary particles and the coarse agglomerates resulting from other formation periods is carried out in the precipitation process, and a material having a bimodal distribution within the scope of the present invention is obtained. It was found to occur.

  Other methods of producing a bimodal particle size distribution synchronously in one precipitation step in a continuous process, in addition to continuous material flow at regular periods, in addition to the number of primary particles due to a sudden metal salt feed. To cause a spontaneous increase. Increasing the number of crystal nuclei results in a second product population having a small particle size.

Thus, the process according to the invention for producing the desired nickel mixed hydroxide-cathode material generally involves nickel mixed hydroxide, such as alkali metal ions, nickel (II), in a loop reactor having an integrated purification zone. ) Ions, ammonia, OH ⁻ ions, and divalent or trivalent cations, especially magnesium, calcium, zinc, cobalt, aluminum, manganese, iron, chromium, rare earth groups and monovalent or divalent A reaction mixture consisting of an aqueous solution of at least one component of the group of valent anions, in particular chloride, nitrate, sulphate, is charged with additional metal ions, in particular said cations, for the formation of mixed oxides. Nickel (II) salt solution, aqueous ammonia solution and alkali metal hydroxide solution The liquid is added, and the resulting particulate nickel mixed hydroxide-cathode material is discharged as a solid together with the proportion of liquid components of the reaction mixture and fed to the solid-liquid separation. In this case, apart from this, the nickel (II) salt solution and the alkali metal hydroxide solution are added almost simultaneously at a substantially constant pH value, or the nickel salt solution and the alkali metal hydroxide solution are continuously added. In addition to the almost simultaneous addition of 0.5 to 15% of the nickel salt solution to be fed and the alkali metal hydroxide solution to be fed at regular time intervals between 0.5 and 5 hours. Can be added to the reaction mixture intermittently without adversely changing the pH value.

  The added nickel (II) salt solution preferably contains 80 to 125 g / l of nickel cations and one or more cations of the group of magnesium, calcium, zinc, cobalt, aluminum, manganese, chromium, iron, rare earth, respectively. 0.1 to 20 g / l.

  This aqueous ammonia solution preferably contains 1 to 25% by weight of ammonia.

  The alkali metal hydroxide solution can consist of an aqueous NaOH solution, an aqueous KOH solution and / or an aqueous LiOH solution, and advantageously consists exclusively of an aqueous NaOH solution. The total alkali metal hydroxide proportion is 10 to 30% by weight, preferably about 20% by weight, based on the total weight of the solution.

The concentration of the reaction mixture in the reaction solution is preferably 50 g / l to 60 g / l and nickel (II) ions 0.1 mg / l to 100 mg with respect to the total concentration of sodium, potassium and lithium during the performance of the process. / L, magnesium, calcium, zinc, cobalt, aluminum and manganese are adjusted to a total concentration of 0.1 mg / l to 100 mg / l with OH ⁻ , chloride, nitrate and / or sulfate as counterions .

  The solid fraction in the reaction mixture is preferably adjusted to 220 g / l to 400 g / l, preferably 300 g / l to 380 g / l.

  The product suspension withdrawn from the mixing region of the loop reactor is divided into a solid-free solution using a known method for solid-liquid separation, for example, a vacuum belt filter, and an adhesion solution of 0.05-0. It is divided into solids having a mass ratio of 35.

  The solid particles discharged together with the reaction solution overflowing in the reactor are collected in the next purification device and returned to the reactor.

  The temperature of the reaction mixture is preferably kept constant over time at intervals of 20 ° C. to 80 ° C., preferably 30 ° C. to 60 ° C., more preferably ± 1 ° C.

  The pH value of the reaction solution is 9.8 to 13.7, preferably 11.6 to 12.9, depending on the temperature, and is kept constant over time within an error of ± 0.05.

  The alkali metal hydroxide solution is fed in the reactor in a molar ratio of 0.9 to 1.3, preferably 1.05 to 1.10, relative to the sum of the cations of the nickel (II) salt solution. This solution is preferably introduced directly below or just above the liquid surface in the reactor.

  This nickel (II) salt solution is preferably introduced below the liquid surface and more preferably into the hydrodynamic loop region in the reactor.

  An aqueous ammonia solution is also particularly preferably introduced immediately below or just above the liquid surface, preferably in the immediate vicinity of the introduction of the nickel (II) salt solution.

This is the case when a nickel-mixed hydroxide of 7 kg / h to 30 kg / h, preferably 18 kg / h to 25 kg / h, is produced per 1 m ^{3 of} reactor volume and the specific throughput is kept constant over time. It turned out to be extremely advantageous for the product.

A particularly advantageous reaction volume is between 1 liter and 100 m ³ . In the case of a particularly advantageous embodiment of the invention, the loop reactor has a tilting blade stirrer, preferably a six-blade tilting blade stirrer with a stirring shaft in the vertical axial direction, , 15 ° to 85 °, has a preferably 30 ° to 60 constant within DEG inclination or increasing ^{slope, 150W / m 3 ~320W / m} 3, preferably 290W ^{/ m 3} ~300W ^/ m 3 At different stirring speeds and different flow rates within the guide tube as well as shear forces in the reaction mixture.

A particularly advantageous method for producing the nickel mixed hydroxide-cathode material according to the invention is based on a combination of mutually controlled chemical, physical and mechanical factors and has the following:
^{- 150W / m 3 ~320W / m} 3, advantageously guaranteed special specific energy introduction of 290W / ^{m 3,}
A guarantee of a specific throughput of 7 kg / h to 30 kg / h, preferably 15 kg / h to 25 kg / h per 1 m ^{3 of} reactor capacity;
- precipitation reactor 220 kg ^/ m 3 related strongly mixing zone of ~400kg / ^{m 3,} preferably modulation of 300kg ^{/ m 3} ~380kg ^/ m 3 solid content - for hydroxide ion, per solution 1 m ³ 0 kg Adjustment of a constant excess of precipitating agent in the range of 10 kg, preferably 1.5 kg to 6.3 kg,
-Adjusting the temperature of the product suspension between 20 ° C and 90 ° C,
-Supply of all necessary material flow at various points of the strongly mixing reaction zone in the upper region of the loop flow,
A guide tube in which the use of a tilting blade stirrer with a constant or increasing inclination of the stirring blade within the range of 15 ° to 85 °, preferably 30 ° to 60 °, influences particle formation within the desired range To produce different flow velocities within the range and shear forces within the suspension.

The reaction mixture for producing the nickel mixed hydroxide-material according to the present invention using the above-mentioned apparatus in a continuous manner comprises the previously produced nickel mixed hydroxide and the alkali metal ions, nickel (II) ions. , Ammonia, alkaline solutions and divalent or trivalent cations such as magnesium, calcium, zinc, cobalt, aluminum, manganese, iron, chromium, rare earths, especially lanthanoids, and monovalent or divalent An anion, for example, an aqueous solution comprising at least one component consisting of a group of chloride, nitrate, and sulfate. To this reaction mixture is added a nickel (II) salt solution having other metal ions, an aqueous ammonia solution and an alkali metal hydroxide solution. This reaction solution contains alkali metal ions 50-60 g / l, nickel (II) ions 0.1-100 mg / l, cations 0.1-100 mg / l and anions 0.1-200 g / l. The nickel (II) salt solution is nickel 80-125 g / l, at least one divalent or trivalent cation such as magnesium, calcium, zinc, cobalt, aluminum, manganese, iron, chromium, rare earth and monovalent or divalent. Valent anions such as chloride, nitrate, sulfate 0.1-20 g / l. This alkali metal hydroxide solution contains 10-30% by weight of at least one of the components of NaOH, KOH, LiOH and optionally additional NH ₃ . This aqueous ammonia solution contains 1 to 25% by mass of ammonia.

  Next, the present invention will be described in detail with reference to the drawings and examples. FIG. 1 is an apparatus flow sheet of a nickel hydroxide-cathode material manufacturing process.

  FIG. 2 is a schematic representation in a loop reactor used for the production of nickel hydroxide material according to the present invention.

  FIG. 3 is a graph showing the UV spectrum of the reaction solution.

  FIG. 4 is a graph showing the particle size distribution after 24 hours.

  FIG. 5 is a graph showing the particle size distribution after 46 hours.

  FIG. 4 is a graph showing the particle size distribution after 78 hours.

  As shown in FIG. 1, there is a nickel solution to be supplied into the storage container 1, an alkali metal hydroxide solution is present in the storage container 2, and an ammonia solution is present in the storage container 3. . The solution from the storage vessel is fed to the heated and insulated loop reactor 6 through the conduits 13, 14 and 15 using the pumps 4 and 5. Via the overflow 16 of the reactor 6, the reaction solution with less solids is supplied to the heated and insulated purification device 7. The underflow of the purification device 7 can be returned to the reactor 6 using the pump 11 via the conduit 18. The excess reaction solution with less solids can be collected in the storage container 8 via the overflow 17 of the purification device 7. Thermal circulation for the purification device 7 and the loop reactor 6 is provided via a heating bath 10 using a pump. The precipitated product from the reactor 6 passes through the reactor underflow 19 and passes through a sieve 12 having an opening of 0.063 mm to remove the excessive particles present, and reaches a solid-liquid separation as a product suspension 19. This process is adjusted by means of the adjusting device 9.

  FIG. 2 shows the structure of a loop reactor with an integrated purification zone that is particularly suitable for the production of nickel mixed hydroxide materials according to the invention. The cylindrical container 21 has, for example, a flat or conical container bottom 22 with one or more wall baffles 23 fixed to the inside of the container 21; for example, the four wall baffles 23 each have an angle of 90 °. It can be shifted and arranged. An overflow groove 24 may be attached to the loop reactor, and an excessive reaction solution containing a small amount of solid is collected and supplied to the purification device 7 through the solution carry-out unit 30. The solid particles carried out together with the reaction solution from the reactor are collected in the next purification device 7 and returned to the reactor. A ring-shaped separation plate 25 and a ring-shaped guide tube 26 are mounted in the container 21 substantially concentrically with the cylinder axis of the loop reactor. Inside the guide tube 26 there is a stirrer 28 operated via a shaft 27, by which the suspension of reaction solution and precipitated product in the loop reactor is moved. This stirrer can be, for example, a tilting blade stirrer 28 with a vertical axial stirring shaft 27, which stir or increase from 15 ° to 85 °, preferably from 30 ° to 60 °. Has a slope. However, a screw conveyor may be incorporated in the guide tube 26. The concentrated crystals or other precipitated products are removed from the loop reactor through the crystal outlet 29 in the bottom region and subsequently filtered.

FIG. 3 shows a typical UV spectrum of the reaction solution used in the process according to the invention for producing a nickel mixed hydroxide-material with a bimodal particle size distribution. Therefore, nickel (II) ions complexed and bound with ammonia were detected on the order of 1 mg / l to 100 mg / l. The remaining nickel content of the complexed and bound reaction solution can be observed by UV spectroscopic analysis and optionally corrected by interfering with pH value adjustment or NH ₃ addition.

  4-6 show the particle size distribution adjusted for various test times in Example 1. FIG. This particle size distribution was measured using laser particle analysis. What is characteristic of this measurement method is that this result is based on volume and relates to the theory of evaluation of an ideal sphere. The investigated samples were prepared by suspending in demineralized water from washed and dried nickel mixed hydroxide-cathode material. The measured particle size distribution based on the volume and the particle size distribution based on the mass could be regarded as the same based on the result of the scanning electron microscope test and the result of the energy dispersive X-ray microanalysis.

Example This example was carried out in the apparatus according to FIG. 1 in a loop reactor according to FIG. In the case of the loop reactor used, as already described, the incorporation of the purification zone allows the average residence time of the solids in the reactor to be selected sufficiently independently of the residence time of the solution. . From different vessels, a) Ni salt aqueous solution with other additives, b) alkaline liquid and c) aqueous ammonia were fed to different areas in the loop reactor, below or above the liquid surface. This starting material feed was made at a controlled temperature and a controlled pH value. The product suspension was moved in a loop reactor using a 6-plate inclined blade stirrer with a vertically extending axial stirrer shaft and a stirrer blade mounted at 15 ° to 85 °. The product was discharged from the mixing zone of the reactor, and the resulting suspension was subsequently filtered. The solid material carried by the reactor overflow with the solution float reaches the purifier and is returned to the reactor from there. The solution overflowing in the purification device was collected in the stack container together with the filtrate.

  The particle size distribution was measured using a master size (laser particle analysis) from Malvern.

  Due to the increase in the residence time of the solid compared to the solution, the solids content rises above 350 g / l. The high particle density of the suspension and the high energy introduction by agitation result in a product with a high tap density, which is suitable as an active material for storage batteries. The mechanical loading of solids in the mixing zone of the reactor is caused by a second population of products having an average particle size between 0.5 μm and 1 μm. This main population showed a median value of 6-12 μm. This method makes it possible to obtain bimodally distributed nickel mixed hydroxides without additional mixing steps.

Example 1
Example 1 describes a continuous manufacturing process.

  Nickel sulfate / zinc solution in 115 g / l nickel and 8.7 g / l zinc is vigorously mixed using a feed pump in a loop reactor with an integrated purification zone and a 400 l charge capacity. Introduced into the area.

As a complexing agent, a 25% ammonia aqueous solution was supplied at a ratio of 0.7 mol of NH _{3 to} 1 mol of nickel immediately in the vicinity of the introduction portion of the sulfate solution. 20% aqueous caustic soda liquor was fed directly into the mixing zone loop flow in the reactor at a ratio of 1.1 mol NaOH to 1 mol nickel. The nickel mixed hydroxide according to the invention was formed at a temperature of the reaction solution of 20 ° C. to 90 ° C. and at a pH value of 12.6. The solid density in the reactor was 350 g / l over a period of 19 h. Thereafter, the crystal was taken out, and the crystal was taken out from the reactor in an amount of 9.5 kg per hour. This specific throughput was about 20 kg / (h · m ³ ). The following properties of the washed and dried nickel mixed hydroxide-material were measured after various reaction times.

  The particle size distribution after the reaction time of 24 hours and the ratio with respect to the total volume are shown in FIG. 4, after 46 hours in FIG. 5, and after 78 hours in FIG.

Example 2:
Example 2 describes a process in which bimodally distributed nickel hydroxide is generated by the sudden addition of nickel sulfate and sodium hydroxide solution.

The nickel sulfate / zinc solution in 115 g / l of nickel and 8.7 g / l of zinc was used for this precipitation in a loop reactor with a built-in purification zone and a charge capacity of 22 liters using a feed pump. It was introduced into the vigorous mixing zone of the reactor. As a complexing agent, a 25% ammonia solution was supplied at a ratio of 0.7 mol of NH _{3 to} 1 mol of nickel immediately in the vicinity of the introduction portion of the sulfate solution. 20% aqueous caustic soda solution was fed directly into the loop flow of the mixing zone in the reactor at a ratio of 1.07 mol NaOH to 1 mol nickel. The temperature in the reaction medium was 60 ° C., and the specific throughput was 20 kg / h m ³ . Nickel mixed hydroxides with an average particle size of the main population of 13-15 μm were obtained. The mass proportion of the subpopulation was 0-4%. After a test time of 52 hours, with a rhythm of 2 hours, 4% nickel sulfate / zinc solution fed every hour at the same time and 16% NaOH solution fed every hour at the same time intermittently into the reactor at the same time. To the reaction medium. Nickel with a median of 12.0 μm main population and median of 0.8 μm subpopulation and a distribution based on mass of 95% vs. 5% main population vs. subpopulation at a test time of 76 hours A mixed hydroxide was obtained.

  The following characteristics of the washed and dried product were measured at various test points:

Example 3:
Example 3 describes a manufacturing process, where after the production of the bimodal nickel mixed hydroxide, the process was stopped, the reactor was emptied and a new process was subsequently started.

This precipitation reaction in a loop reactor equipped with a purification zone incorporated with 115 g / l nickel and 8.7 g / l zinc with a feed pump and with a charge capacity of 22 liters Introduced into the powerful mixing area of the vessel. As a complexing agent, a 25% ammonia solution was supplied at a ratio of 0.7 mol of NH _{3 to} 1 mol of nickel immediately in the vicinity of the introduction portion of the sulfate solution. 20% aqueous caustic soda solution was fed directly into the loop flow of the mixing zone in the reactor at a ratio of 1.3 mol NaOH to 1 mol nickel. The temperature in the reaction medium was 40 ° C. and the specific throughput was 20 kg / h m ³ . Discharge of the product suspension from the reactor, since the test time of 16 hours, 60 per liter reaction volume 1 m ³ per hour, the solids content in the volume of the mixed zone, 55 tests Over the time space, it rose to 450 g per liter of suspension volume. The following periodic particle size distribution occurred at the test conditions held constant. At the start of the test (7 test times), a product having a unimodal particle size distribution and an average particle size of 5.8 μm was obtained. At 55 test times of maximum solids content, it has a distribution based on the median of the main set of 7.8 mm, the median of the subset of 0.7, and the mass of the main set versus subset of 96: 4 A product with a bimodal distribution was obtained. A product with a unimodal distribution with a median of 4.5 μm was obtained after 78 test times, with a median of the main population of 5.4 μm and a median of the subpopulation of 0.7 μm, and 90 : A product of a bimodal distribution with a distribution based on the mass of 10 main populations vs. subpopulations was obtained after 93 test hours.

  The following characteristics of the washed and dried product were measured at various test points:

Equipment flow sheet for nickel hydroxide-cathode material manufacturing process. 1 is a schematic representation in a loop reactor used for the production of nickel hydroxide material according to the invention. The figure which shows the UV spectrum of a reaction solution with a graph. The figure which shows the particle size distribution after 24 hours with a graph. The figure which shows the particle size distribution after 46 hours with a graph. The figure which shows the particle size distribution after 78 hours by a graph.

Claims (23)

  In nickel mixed hydroxide-cathode materials with a bimodal particle size distribution for use in alkaline storage batteries, the median particle size distribution based on mass of the main population, derived from laser particle analysis, is between 5 μm and 25 μm. The median particle size distribution based on the mass of the subpopulation measured by the same method is 0.3 to 3 μm, and the mass proportion of the main population is 70 to 96% by mass, Nickel mixed hydroxide-cathode material having a good particle size distribution.   The nickel mixed hydroxide-cathode material according to claim 1, wherein the median of the main population of particles is 6 to 12 µm and the median of the subpopulation is 0.3 to 1.5 µm. 3. Nickel mixed hydroxide according to claim 1 or 2, characterized in that the width between the percentiles D _90% and D _10% of the particle size distribution based on the mass of the main and subpopulations does not overlap -Cathode material.   A nickel (II) cation and a divalent or trivalent cation, particularly magnesium, calcium, zinc, cobalt, aluminum, manganese, iron, chromium, containing at least one component consisting of rare earth groups The nickel mixed hydroxide-cathode material according to any one of claims 1 to 3.   Nickel according to any one of claims 1 to 4, characterized in that the mixed hydroxide contains a monovalent or divalent anion, in particular an anion consisting of chloride, nitrate, sulphate. Mixed hydroxide-cathode material.   6. Nickel-mixed hydroxide-cathode according to claim 1, characterized in that the nickel proportion is 40-60% by weight, preferably 55-59% by weight, based on the dry material. material. Nickel mixed hydroxide according to any one of claims 1 to 6, characterized in that the specific surface area is 10 to 100 m ² / g (BET), preferably 15 to 40 m ² / g (BET). -Cathode material. The method for producing a nickel mixed hydroxide-cathode material according to any one of claims 1 to 7, wherein a nickel mixed hydroxide, an alkali metal ion, At least one component consisting of nickel (II) ions, ammonia, OH ⁻ ions and divalent or trivalent cations, in particular magnesium, calcium, zinc, cobalt, aluminum, manganese, iron, chromium, rare earths, and Charging a reaction mixture consisting of an aqueous solution comprising at least one component of the group of monovalent or divalent anions, in particular chloride, nitrate, sulphate, for the formation of mixed hydroxides, further metal ions, In particular, nickel (II) salt solution, ammonia aqueous solution and alkali metal water having the above cation A method for producing a nickel mixed hydroxide-cathode material comprising adding an oxide solution and discharging the resulting particulate nickel mixed hydroxide-cathode material together with the reaction mixture as a solid and filtering .   9. A process according to claim 8, characterized in that the nickel (II) salt solution and the alkali metal hydroxide solution are added almost simultaneously at a substantially constant pH value.   In addition to the continuous and nearly simultaneous addition of nickel salt solution and alkali metal hydroxide solution, in addition, at regular time intervals between 0.5 and 5 hours, without adversely changing the pH value 10. Process according to claim 8 or 9, characterized in that 0.5 to 15% volume fraction of the nickel solution to be supplied and the alkali metal hydroxide solution to be supplied is intermittently added to the reaction mixture.   The added nickel (II) salt solution contains 80 to 125 g / l of nickel and one or several cations in the group of magnesium, potassium, zinc, cobalt, aluminum, manganese, iron, chromium and rare earth, respectively. The method according to any one of claims 8 to 10, characterized in that it contains ~ 20 g / l.   The method according to any one of claims 8 to 11, wherein the aqueous ammonia solution contains 1 to 25% by mass of ammonia.   The alkali metal hydroxide solution consists of an aqueous NaOH solution, an aqueous KOH solution and / or an aqueous LiOH solution, preferably only an aqueous NaOH solution, and the total alkali metal hydroxide ratio is 10 to 30 mass relative to the total mass of the solution. 13. A process according to claim 8, characterized in that it is%, preferably about 20% by weight. The concentration of the reaction mixture in the reaction solution during the performance of the process is 50 g / l to 60 g / l with respect to the total concentration of sodium, potassium and lithium and 0.1 mg / l to 100 mg / l of nickel (II) ions, magnesium, The total concentration of calcium, zinc, cobalt, aluminum, manganese, iron, chromium and rare earth is adjusted to 0.1 mg / l to 100 mg / l, with OH ⁻ , chloride, nitrate and / or sulfate as counter ions. 14. The method according to any one of claims 8 to 13, characterized in that:   15. The process as claimed in claim 8, wherein the solid fraction in the reaction mixture is adjusted to 220 g / l to 400 g / l, preferably 300 g / l to 380 g / l.   The process according to any one of claims 8 to 15, characterized in that the solid particles transported together with the reaction solution from the reactor are collected in a subsequent purification device and returned to the reactor.   17. The temperature of the reaction mixture is 20 ° C. to 80 ° C., preferably 30 ° C. to 60 ° C., more preferably maintained constant over time at intervals of ± 1 ° C. The method of any one of these.   The pH value of the reaction solution is 9.8 to 13.7, preferably 11.6 to 12.9, depending on the temperature, and should be kept constant in time within an error of ± 0.05. 18. A method according to any one of claims 8 to 17, characterized in that   The alkali metal hydroxide solution is fed in the reactor in a molar ratio of 0.9 to 1.3, preferably 1.05 to 1.10, relative to the sum of the cations of the nickel (II) salt solution. 19. A method according to any one of claims 8 to 18, characterized in that   20. Process according to any one of claims 8 to 19, characterized in that the alkali metal hydroxide solution is introduced directly below or just above the liquid surface in the reactor.   21. Process according to claim 8, characterized in that the nickel (II) salt solution is introduced directly below the liquid surface in the reactor, preferably in the hydrodynamic loop region. .   Aqueous ammonia solution is introduced immediately below or just above the liquid surface in the reactor, preferably in the immediate vicinity of the introduction of the nickel (II) salt solution. The method according to claim 1. The reaction is carried out using a tilting blade stirrer, preferably using a 6-plate tilting blade stirrer with a stirring shaft in the vertical axis, said stirring blade being between 15 ° and 85 °, preferably 30 °. an inclined to constant slope or increased within 60 ^{DEG, 150W / m 3 ~320W / m} 3, preferably at a stirring intensity of ^{290W / m 3 ~300W / m 3} , and the range of the guide tube 23. Process according to any one of claims 8 to 22, characterized in that shear forces are produced in the reaction mixture as well as different flow rates.

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