Title of Invention

AN IMPROVED SINGLE STEP PROCESS FOR THE PREPARATION OF BATTERY GRADE ALPHA NICKEL HYDROXIDE

Abstract

The present invention provides an improved process for the preparation of battery grade nickel hydroxide by electrochemical method using ethanol as solvent. The raw material used I the present invention is nickel solution from nickel nitrate and commercially available 99.9% ethanol. In some cases cobalt was added as additives to increase the utilization of nickel hydroxide electrode. The XRD graph obtained with sharper and narrow peak with peaks at 11°, 22°, 33.5°, 60°. This suggests that the samples obtained are highly crystalline (orderliness) in nature with a motif. The nickel hydroxide with α-formed was identified in all the cases. A maximum tapped density of 1.87g/cc was observed and specific discharge capacity per one gram of nickel hydroxide was observed to vary in the range of 200-215 mAh, when discharge rate was 80mA.

Full Text

Field of the invention The present invention relates to an improved single step process for the preparation of battery grade a-nickel hydroxide from nickel nitrate. More particularly, the present invention relates to an improved single step process for the preparation of battery grade a-nickel hydroxide from nickel nitrate by electrochemical method using ethanol as solvent. Background of the invention The invention largely falls in the field of material preparation for energy storage. In all nickel based rechargeable (secondary) batteries such as Ni-cadmium, Ni-metal hydride, Ni-iron etc. nickel hydroxide is used as positive electrode material. These batteries are high energy density batteries with respect to unit weight and volume, low manufacturing cost, low maintenance cost during use, long service life, free of toxic material, high reliability. Due to this characteristic, the present consumer electronic market spurted to use these batteries. Some multinational companies are going to introduce zero emission electric vehicles based on these batteries. The development of alternative energy sources is becoming a practical and urgent challenge for scientists and engineers all over the world; since the global supply of gasoline will be exhausted in a few decades due to the rapid rate of petroleum consumption. Batteries have become one of the most promising alternative energy sources because of their extensive application in everyday life. The worldwide market for rechargeable batteries for consumer electronic applications is growing at higher rate. Currently the Ni-cadmium and Ni-metal hydride batteries are used in aircraft, telecommunications, military and defense. Portable devices (photography, portable phones, portable computers, camcorders, power tools, toys) and stand by power systems (emergency lighting), alarms etc. require the above batteries. These are also used in areas like rural electrifications, railways, electric vehicles, industrial traction and oilrigs etc. Faced with the problems caused by the internal combustion engine vehicles, the environmentalists put forth idea of electric vehicles (EVs) sharing a part of the urban transport requirements, particularly in metropolitan cities. The idea of "clean air" and " global warming" has contributed to the hectic activities seen now a day in the development of suitable zero emission EVs, hybrid electric vehicles (HEVs) and EV batteries. The battery systems available now are conventional lead acid and advanced lead acid, Ni-cadmium, Ni-metal hydride etc. The main draw back of lead acid battery is its heavy weight. Nickel based rechargeable batteries are good alternative for this problem. Again nickel hydroxide can be very attractive materials in view of their potential application in "smart windows". Such windows have variable light transmission characteristic and may be use full for applications in building and car industries. The global demand for nickel hydroxide is estimated to be 100,000 tones per annum and is expected to grow at a rate of 20-40% per year with the introduction of electric vehicles. The total market for batteries in India is estimated to be valued at ~Rs 1500 crore. The market is growing at the rate of 10-12%. In the developed countries alkaline batteries contribute about 55-60% of the total battery market. This trend is expected to follow in the developing countries and India is not an exception. The Indian market witnessed the usefulness of alkaline batteries only in 1994, after the liberalization process started. With increasing demand, alkaline and rechargeable batteries are expected to contribute significant market in this country. There is no method for preparation of nickel hydroxide in India suitable to battery industry. Keeping in view of development of consumer electronic market and fourth coming emission free electric vehicle, it become the most challenging task to develop an Indigenous technology to prepare battery grade nickel hydroxide, the positive electrode material for nickel based rechargeable alkaline batteries. Again the process should be viable to Indian economy and availability of raw material. Generally divalent nickel hydroxide has always been made by precipitation from an aqueous solution containing a nickel salt eg. nickel sulphate by addition of or admixture with an aqueous solution of an alkaline hydroxide, NaOH. When in these manner nickel hydroxide is almost always contaminated with measurable amounts of cation of the alkaline hydroxide and the anion of the nickel salt. Even though the byproduct of precipitation eg. Sodium sulphate is very soluble in water, washing of the gelatinous nickel hydroxide precipitate is very difficult. Furthermore, the gelatinous precipate almost always gives a low tapped density nickel hydroxide product directly upon drying. The major producers of nickel hydroxide are Tanaka Chemicals (Japan), Sumitamo Metal Mining Corporation (Japan), INCO (Canada), Sheritt (Canada), H. C. Stark (Germany), UMEX USA etc. And the major consumers of nickel hydroxide are Matsushita Japan, Sanyo Japan, Toshiba Japan, Hitachi Japan, Nippon Storage Battery Japan, HBLNIFE Hyderabad India. The entire requirement of this material in India is met through imports, as no suitable Indigenous technology is still available. It is important to prepare nickel hydroxide with required specifications for battery application. The foreign companies which are producing nickel hydroxide commercially by chemical method keep the trade secret within themselves. So it is necessary to develop a technology in India for preparation of battery grade nickel hydroxide. Nickel hydroxide has a specific discharge capacity of 289mAh/g. For suitability of a Ni-Cd, Ni-MH battery the discharge capacity is needs to be170mAh/g of nickel hydroxide when discharging @ 80mA (0.3C). Its discharge capacity depends upon its preparation condition and structure. Morphologically two types of nickel hydroxide are present, α-nickel hydroxide and p-nickel hydroxide. Theoretically α-nickel hydroxide has a higher discharge capacity and more crystalline compare to p-nickel hydroxide. The X-ray peaks reflects how well structured the crystal is: the sharper and narrower the peak, the more the degree of crystalinity (orderliness), while the wider the peak, the less the degree of crystalinity (disorderliness). Typically, the sharpness of these peaks is expressed in terms of the half-height width of the 2.THETA angle. At least one reference indicates that peak half-height width of 0.8 degree. Or more of the (101) plane results in better charge/discharge efficiency. The drawbacks related to the use of nickel hydroxide electrodes in alkaline batteries is the tendency of the electrode to swell or expand during charging, particularly during over charge portion of the cycle. The swelling is known to reduce the number of charge/discharge cycles that the battery can withstand, i.e., cycle life, by causing mechanical failures of the battery. Swelling on the macroscopic level is usually explained at the microstructure level by the formation of the lower density, more voluminous gamma-phase NiOOH crystallites. The presence of cobalt and other transition metal ions thought to change the interlayer bonding forces of the nickel crystal lattice, thusly suppressing the formation of the gamma-NiOOH. Again during charging there are two competing reaction occurs simultaneously. One is oxidation of nickel hydroxide electrode and another is oxygen evolution reaction. The oxygen evolution reaction is not desirable and contributes to lower utilization rates upon charging. One reason both occur is that their electrochemical reaction potential values are very close. Any thing that can be done to widen the gap between them, lowering the nickel reaction potential in reaction (1) or raising the oxygen evolution potential in reaction (2) will contribute to higher utilization rates. Cobalt as a dopant is thought to affect the Ni+2 to Ni+3 reversibility and lower the nickel reaction potential in reaction. Thus oxidation of nickel electrode can be done with a lower potential where oxygen evolution reaction will not happen. So efforts are made to prepare α-nickel hydroxide with higher discharge capacity. Various processes are available for preparation of nickel hydroxide. But none of the literature gives the information about the commercial preparation of nickel hydroxide. The prime feature of the present invention is to provide a dry nickel hydroxide product, which has a high tapped density high discharge capacity after drying. Another feature of the present invention is to provide a nickel hydroxide, which is more crystalline and relatively pure. The first and second features of the invention are accomplished by the third object of the invention, which is to provide a low cost single step novel process for manufacture of a-nickel hydroxide. When a nitrate solution is subjected to electrolysis, nitrate ion insitu reduced to ammonia. Simultaneously formation of hydroxyl ion causes a change in the local pH. Due to this increase in alkalinity occur and metal ion if present, starts precipitation of metal hydroxide. Electrochemically prepared substances are comparatively pure and needs less washing. Probability of formation of a-nickel hydroxide is more in case of electrochemical method of preparation. Reference may be made to Aladjov, U. S. Patent, (1998) 5,788,943, wherein nickel hydroxide for use in an electrode of a rechargeable battery is prepared by controlled precipitation from a neutralized reaction mixture of a nickel salt and an alkali metal hydroxide. For precipitation of nickel hydroxide a suitable pH and temperature was maintained in which insoluble nickel hydroxide will precipitate. The improvement made was introduction of ultrasonic energy during the formation of the nickel hydroxide to alter the micro and macrostructure and the resulting properties of the nickel hydroxide. Here also removal of cation and anion from the gelatinous precipate is a major problem and conventional caustic precipitation techniques create the environmental problem of disposing of large quantities of this by-product. The cost of properly disposing of this by-product adds significant costs to the price of nickel hydroxide. Reference may be made to Ettel. et al., U. S. Pattent (1994) 5,281,494, wherein nickel hydroxide was prepared by chemical processes at a temperature of 150-300°C, using a fine nickel metal, produced by decomposition of nickel carbonyl [Ni(CO)4] having a surface area of at least about 0.1m2/g. The reaction was carried out with an excess of water in a autoclave at a steam partial pressure of 10-30 atmosphere and a continuous supply of oxygen at a partial pressure of 5-25 atmosphere. Ammonia or ammonia plus ammonium salts or carboniferous catalyst were used as reaction catalyst. In many cases they used cobalt, cadmium, barium, lithium etc. as dopant to increase the efficiency of the nickel hydroxide. Here particulate nickel is reacted with oxygen in the presence of liquid water at an elevated temperature. For this reaction to occur, catalyst another chemical is essential. Extra energy is needed for maintaining the temperature. The raw material the nickel powder production is itself a tedious process. Reference may be made to Babjak, et al. U. S. Patent (1995) 5,447,707, wherein Nickel hydroxide was prepared by chemical method from nickel metal powder. Here nickel powder was directly introduced to an aqueous solution containing nitrate ion either from nitric acid or nickel nitrate or from ammonium nitrate. The pressure was maintained about one atmospheric and the temperature range of about room temperature to 95°C was kept to generate nickel hydroxide. Ammonia was introduced to maintain pH of the solution in a range from about 8.5 to 10. During chemical reaction ions selected from the group consisting of cobalt, cadmium, zinc, iron, lithium, and barium are introduced to the solution to increase the charge efficiency of the nickel electrode. In this process the nitrate ion in the solution act as a reactant and is consumed as it oxidizes the nickel metal to Ni+2 state for the subsequent combination with the OH" ion conjugate base to form nickel hydroxide and ammonia. The raw material nickel powder was formed as a result of thermal decomposition of nickel carbonyl. The nickel hydroxide so produced was separated from reacting solution and dried. Nickel metal powder preparation is a tedious process, which is a raw material for the purpose. And the whole process is a condition specified process. Reference may be made to Coates, et al. U. S. Patent (2001) 6,193,871, wherein in a two steps processes nickel hydroxide was prepared by electrochemical method. In first step an oxide and hydroxide of a zinc salt was deposited to a porous electrode substrate thereafter nickel active material was deposited to the electrode. A current density of 0.005 to 0.02 A/cm2 was applied for the polarizing process. The bath was buffered with about a 1.0 molar solution of sodium nitrate to maintain pH of 1.8 to 2.2. Extra energy was used for maintaining temperature of about 80-95 °C. Cobalt hydroxide was co-precipitated with nickel hydroxide as additive for better result. After formation of nickel hydroxide, it was dried at 60°C. Objectives of the invention The main objective of the present investigation is to provide an improved single step process for the preparation of battery grade a-nickel hydroxide from nickel nitrate by electrochemical method using ethanol as solvent. Another object of the present investigation is to provide battery grade dry nickel hydroxide electrochemically, with high tapped density and high discharge capacity. Yet another object is to provide a process for the preparation of highly crystalline a- nickel hydroxide. Still another object is to provide a process for the preparation of low cost α-nickel hydroxide suitable to Indian economy and availability of raw materials in India. Summary of the invention Accordingly the present invention provides an improved single step process for the preparation of battery grey alpha-nickel hydroxide and the said process comprising the steps of: a) preparing a solution of nickel nitrate in an organic solvent, preferably alcohol or a mixture of alcohol and water, b) electrolysing the above said nickel nitrate solution in a diaphragm cell preferably made of polypropylene containing a cathode made of stainless steel and an anode made of iridium coated titanium, at a current density of 30-200A/m2, optionally in the presence of cobalt additive, for a period of 20-25 hrs, to obtain the resultant green precipitates of nickel hydroxide at cathodic chamber, followed by filtration and washing the resultant residue with water and drying by known method to obtain the desired product. In an embodiment of the present invention the organic solvent used is ethanol. In yet another embodiment the ratio of alcohol to water in a mixture of alcohol and water is 1:1. In yet another embodiment the current density used in electrolysis reaction in step (b) is preferably in the range of 30-100 A/m2 in the absence of cobalt additive. In yet another embodiment the current density used in step(b) is in the range of 200-220 A/m2 in the presence of cobalt additive. In yet another embodiment the cobalt additive used is cobalt nitrate. In yet another embodiment the quantity of cobalt additive used is in the range of 2-3gpl. In yet another embodiment the temperature used for drying the green precipitates of nickel hydroxide after washing in step(b) used is in the range of 60-70°C for a period of 40-48 hrs. In yet another embodiment the alpha-nickel hydroxide obtained has a discharge capacity in the range of 195-220 mAh/g. Detail description of the invention In the present study nickel hydroxide was prepared from nickel nitrate electrochemically in a single step. The solvent used either commercially available 99.9% pure ethanol or a mixture of ethanol and water 50%v. In some cases cobalt 2gpl from cobalt nitrate was used as additive. The electrolysis was carried out in a diaphram cell by DC power from a regulated DC power supply unit. A suitable applied current was chosen for the electrolysis process. After the electrolysis was complete the catholyte slurry was filtrated through Whatman No. 1 filter paper, washed thoroughly by distilled water and dried at 60-70°C for 48 hours. The diaphram cell is made up of perspex (acrylic material) sheet from nickel nitrate solution as electrolyte. The diaphram material was polypropylene. The electrodes used were stainless steel cathode and iridium coated titanium anode of suitable dimension. The electrolysis was carried out applying DC current from a regulated power supply unit with a predetermined current. Nickel nitrate solution was prepared using either commercially available 99.9% pure ethanol or a mixture of ethanol and water (50-50%v). A suitable applied current was chosen for the electrolysis process. A lower current density of 50 A/m2 was chosen to prepare nickel hydroxide without cobalt additive and a higher current density 200 A/m2 for preparation of nickel hydroxide with 2gpl cobalt additive from cobalt nitrate. The green colour nickel hydroxide obtained in a single step; by electrolyzing the above nickel solution in ethanol with and without cobalt additive at cathodic chamber was filtrated by Whatman No-1 filter paper. The sample was washed thoroughly by distilled water. The washed sample was dried in an electric oven at 60-70°C for 48 hours. Then the sample was characterized by XRD and the discharge capacity was measured by a sophisticated charge-discharge unit, provided by Bitrode Corporation Ltd, USA. The present invention provides an improved single step process for production of battery grade α-nickel hydroxide from nickel nitrate by electrochemical method using ethanol as solvent, which comprises the following steps: (a) preparation of a standard solution of nickel from nickel nitrate either commercially available 99.9% pure ethanol or a mixture of ethanol and water (50-50%v), (b) preparation of a diaphram cell using polypropylene as diaphram material, (c) polishing the stainless steel cathode and iridium coated titanium electrodes by emery paper, washed by distilled water followed by air drying, placing in the cell and connecting to the circuit for electrolysis, (d) electro crystallisation of nickel hydroxide by electrolyzing the nickel nitrate solution using a regulated DC power source with a suitable applied current (lower current density of 50A/m2 to prepare nickel hydroxide without cobalt additive and higher current density 200A/m2 with cobalt additive), (e) filtration of nickel hydroxide from catholyte solution by Whatman No-1 filter paper followed by washing by distilled water and drying by an electric oven was carried out at 60-70°C, (f) determination of structure by XRD and discharging capacity was carried out by a standard charge discharge unit. The nickel hydroxide was prepared by electrochemical method using a diaphragm cell. The diaphragm cell was prepared from perspex (acrylic material) sheet having length 24cm, width 20.5cm and height 20cm. The anode was a iridium coated titanium substrate insoluble material of 0.3 cm thickness having dimensions; length 20cm with dipping up to 17cm, width 18cm. the cathode was a stainless 316 sheet, having the dimensions length 20cm, and width 18cm. the electrodes were placed into the cell and connected to the circuit for nickel hydroxide precipitation. Each chamber has the content capacity was 4.5 liter. The electrolysis was carried out by applying a specified DC current from a regulated power supply unit (lower current density of 50A/m2 to prepare nickel hydroxide without cobalt additive and higher current density 200A/m2 with cobalt additive). The electrolyte was prepared from nickel nitrate using ethanol as solvent at low current without cobalt additive and at high current with cobalt additive. The X-Ray diffraction patterns of the samples were obtained using a Philips Powder Diffractometer in the range of 10-70° (26) at a scanning rate of 2°/minute with Ni filtered Cu target. Charge discharge measurements were carried out at laboratory using a Bitrode Deep Cycle Tester, as per the test procedures followed by the battery industries. For charge discharge test, 2 gm of nickel hydroxide was mixed thoroughly with 1gm of graphite powder. Three drops of aqueous suspension of 5% poly vinyl alcohol was used as binder. The mixture was placed in a stainless still mesh and palletized under pressure of 350kg/cm2 for 6 minutes using 20mm dye. Nickel hydroxide thus prepared was used as a positive electrode. Two nickel plates of dimensions length 8.0cm; width 5.0cm were used as counter electrodes. The nickel hydroxide pellet was charged at a current rate of 80mA for 9 hours and the electrolyte used was 30 % KOH solution. After resting of 10 minutes the discharge was carried out at a current of 80mA using Zinc sheet of 99.9% purity having dimensions as; length 5cm and width 1cm as counter electrode until the electrode potential of nickel hydroxide reached 1.5 volts. During charging the cell potential was raised to 1.9 volts and the open circuit potential 1.8 volts. The process developed for the preparation of nickel hydroxide electrochemically. The novelty of the present process is that a high value added product can prepared from nickel nitrate (synthetic or by product of plants) electrochemically in an indigenous technology using ethanol as solvent at a low current without cobalt additive and at a high current with 2gpl cobalt additive. So far there is not a suitable commercial process for preparation of nickel hydroxide by indigenous technology is available. The following examples are given by the way of illustration of the working of the invention in actual practice and therefore should not be constructed to limit the scope of the present invention. Example-1 A 60 gpl nickel solution was prepared from nickel nitrate using commercially available 99.9% ethanol as solvent. In each chamber of diaphram cell as discussed earlier, around 4.5 liter nickel solution was filled. Stainless still and iridium coated titanium electrode were put in to the cell. The two electrodes were connected to DC circuit keeping stainless still as cathode and titanium as anode. The electrolysis was carried out at a lower current of 1.53A (current density 50 A/m2) for 24 hour. The green precipitate obtained at cathodic chamber was filtrated through Whatman No. 1 filter paper. The residue was washed thoroughly by distilled water. After washing, the sample was kept in an electric oven for 48 hour maintaining a temperature of 60-70°C. The dried sample was ground by a mortar pastel to fine powder. The powder obtained was analyzed by XRD analysis. The sample obtained in the above process was identified both α&p-nickel hydroxide. The tapped density was found to be 1.87g/cc. Suitable pellet was prepared from prepared nickel hydroxide powder as discussed earlier. The nickel hydroxide pellet was charged at a current rate of 80mA for 9 hours and the electrolyte used was 30 % KOH solution. After resting of 10 minutes the discharge was carried out at a current of 80mA using Zinc sheet of 99.9% purity as counter electrode until the electrode potential of nickel hydroxide reached 1.5 volts with respect to Zn sheet. The discharge capacity was found to be 205 mAh/g. The corresponding cell voltage during discharging has been given in Tablet Table-1.(Table Removed) Example-2 A slurry was charge identical to that of example-1, except that 2gpl cobalt from cobalt nitrate as additive was added to catholyte. And the electrolysis was carried out at a higher current of 6.12A (current density 200A/m2). The sample obtained in the above process have been identified both a-nickel hydroxide. The tapped density was found to be 1.81g/cc. Suitable pellet was prepared from prepared nickel hydroxide powder as discussed earlier. The nickel hydroxide pellet was charged at a current rate of 80mA for 9 hours and the electrolyte used was 30 % KOH solution. After resting of 10 minutes the discharge was carried out at a current of 80mA using Zinc sheet of 99.9% purity as counter electrode until the electrode potential of nickel hydroxide reached 1.5 volts with respect to Zn sheet. The discharge capacity was found to be 200 mAh/g. The corresponding cell voltage during discharging has been given in Table 2. Table-2. (Table Removed) Example-3 Approximately the same slurry was charged to the electrolytic chamber as in example-1, but the solution prepared from nickel nitrate using 50%v of commercially available 99.9% ethanol with distilled water. The sample obtained in the above process was identified as a-nickel hydroxide. The tapped density was found to be 1.84g/cc. Suitable pellet was prepared from prepared nickel hydroxide powder as discussed earlier. The nickel hydroxide pellet was charged at a current rate of 80mA for 9 hours and the electrolyte used was 30 % KOH solution. After resting of 10 minutes the discharge was carried out at a current of 80mA using Zinc sheet of 99.9% purity as counter electrode until the electrode potential of nickel hydroxide reached 1.5 volts with respect to Zn sheet. The discharge capacity was found to be 215 mAh/g. The corresponding cell voltage during discharging has been given in Table 3. Table-3. (TableRemoved) Example-4 Approximately the same slurry was charged to the electrolytic chamber as in example-2, but the solution prepared from nickel nitrate using 50%v of commercially available 99.9% ethanol with distilled water. The sample obtained in the above process was identified as a-nickel hydroxide. The tapped density was found to be 1.80g/cc. Suitable pellet was prepared from prepared nickel hydroxide powder as discussed earlier. The nickel hydroxide pellet was charged at a current rate of 80mA for 9 hours and the electrolyte used was 30 % KOH solution. After resting of 10 minutes the discharge was carried out at a current of 80mA using Zinc sheet of 99.9% purity as counter electrode until the electrode potential of nickel hydroxide reached 1.5 volts with respect to Zn sheet. The discharge capacity was found to be 210 mAh/g. The corresponding cell voltage during discharging has been given in Table 4. Table-4. (Table Removed) Example-5 A 60 gpl nickel solution was prepared from nickel nitrate using 50%v of commercially available 99.9% ethanol with distilled water. In each chamber of diaphram cell as discussed earlier, around 4.5 liter nickel solution was filled. Stainless still and iridium coated titanium electrode were put in to the cell. The two electrodes were connected to DC circuit keeping stainless still as cathode and titanium as anode. The electrolysis was carried out at a lower current of 0.918A (current density 30 A/m2) for 24 hour. The green precipitate obtained at cathodic chamber was filtrated through Whatman No. 1 filter paper. The residue was washed thoroughly by distilled water. After washing, the sample was kept in an electric oven for 48 hour maintaining a temperature of 60-70°C. The dried sample was ground by a mortar pastel to fine powder. The powder obtained was analyzed by XRD analysis. The sample obtained in the above process was identified both a&p-nickel hydroxide. The tapped density was found to be 1.88g/cc. Suitable pellet was prepared from precipitated nickel hydroxide powder as discussed earlier. The nickel hydroxide pellet was charged at a current rate of 80mA for 9 hours and the electrolyte used was 30 % KOH solution. After resting of 10 minutes the discharge was carried out at a current of 80mA using Zinc sheet of 99.9% purity as counter electrode until the electrode potential of nickel hydroxide reached 1.5 volts with respect to Zn sheet. The discharge capacity was found to be 220 mAh/g. The corresponding cell voltage during discharging has been given in Table 1. Table-1. (Table Removed) Example-6 A 60 gpl nickel solution was prepared from nickel nitrate using 50%v of commercially available 99.9% ethanol with distilled water. In each chamber of diaphram cell as discussed earlier, around 4.5 liter nickel solution was filled. Stainless still and iridium coated titanium electrode were put in to the cell. The two electrodes were connected to DC circuit keeping stainless still as cathode and titanium as anode. The electrolysis was carried out at a current of 3.06A (current density 100 A/m2) for 24 hour. The green precipitate obtained at cathodic chamber was filtrated through Whatman No. 1 filter paper. The residue was washed thoroughly by distilled water. After washing, the sample was kept in an electric oven for 48 hour maintaining a temperature of 60-70°C. The dried sample was ground by a mortar pastel to fine powder. The powder obtained was analyzed by XRD analysis. The sample obtained in the above process was identified both a&p-nickel hydroxide. The tapped density was found to be 1.80g/cc. Suitable pellet was prepared from precipitated nickel hydroxide powder as discussed earlier. The nickel hydroxide pellet was charged at a current rate of 80mA for 9 hours and the electrolyte used was 30 % KOH solution. After resting of 10 minutes the discharge was carried out at a current of 80mA using Zinc sheet of 99.9% purity as counter electrode until the electrode potential of nickel hydroxide reached 1.5 volts with respect to Zn sheet. The discharge capacity was found to be 195 mAh/g. The corresponding cell voltage during discharging has been given in Table 1. Table-1. (Table Removed) Example-7 A 60 gpl nickel solution was prepared from nickel nitrate using distilled water. In each chamber of diaphram cell as discussed earlier, around 4.5 liter nickel solution was filled. Stainless still and iridium coated titanium electrode were put in to the cell. The two electrodes were connected to DC circuit keeping stainless still as cathode and titanium as anode. The electrolysis was carried out at a current of 6.12A (current density 200 A/m2) for 24 hour. The green precipitate obtained at cathodic chamber was filtrated through Whatman No. 1 filter paper. The residue was washed thoroughly by distilled water. After washing, the sample was kept in an electric oven for 48 hour maintaining a temperature of 60-70°C. The dried sample was ground by a mortar pastel to fine powder. The powder obtained was analyzed by XRD analysis. The sample obtained in the above process was identified both ß-nickel hydroxide. The tapped density was found to be 1.35g/cc. Suitable pellet was prepared from precipitated nickel hydroxide powder as discussed earlier. The nickel hydroxide pellet was charged at a current rate of 80mA for 9 hours and the electrolyte used was 30 % KOH solution. After resting of 10 minutes the discharge was carried out at a current of 80mA using Zinc sheet of 99.9% purity as counter electrode until the electrode potential of nickel hydroxide reached 1.5 volts with respect to Zn sheet. The discharge capacity was found to be 160 mAh/g. The corresponding cell voltage during discharging has been given in Table 1. Table-1. (Table Removed) Table-1, Results of Seven examples given in the Patent Proposal (Previously four and now three). The main features of the present invention are: 1. The sample prepared using ethanol as solvent gives high tapped density (1.87 g/cc example-1) with better discharge capacity. 2. Cobalt additive improves the discharge capacity for the sample prepared at higher current. 3. The sample precipate at low current density without cobalt additive shows better discharge capacity (215mah/g prepared at current density 50A/m2, example-3). 4. At high current density better quality of nickel hydroxide can be prepared in the presence of cobalt additive (examples-2 & 4). 5. Battery grade α-nickel hydroxide with high discharge capacity can be prepared by electrochemical method using ethanol as solvent at a higher current density and without cobalt at a lower current density. The main advantages of the present invention are: 1. Electrochemical method is a pollution free process for production of nickel hydroxide. 2. Ethanol is a bio friendly solvent and easily available. 3. The sample obtained by this method is highly pure, and needs less washing. 4. The material prepared instantaneously in a single step at room temperature. So no extra energy is needed to maintain the temperature. 5. Possibilities are there for formation of a-nickel hydroxide with high discharge capacity by electrochemical method using ethanol as solvent. 6. No catalyst is needed for the reaction to occur. 7. The process has potential for commercialization. We claim 1) An improved single step process for the preparation of battery grey alpha-nickel hydroxide and the said process comprising the steps of: a) preparing a solution of nickel nitrate in an organic solvent, preferably alcohol or a mixture of alcohol and water, b) electrolysing the above said nickel nitrate solution in a diaphragm cell preferably made of polypropylene containing a cathode made of stainless steel and an anode made of iridium coated titanium, at a current density of 30-200A/m2, optionally in the presence of cobalt additive, for a period of 20-25 hrs, to obtain the resultant green precipitates of nickel hydroxide at cathodic chamber, followed by filtration and washing the resultant residue with water and drying by known method to obtain the desired product. 2. An improved process as claimed in claim 1, wherein the organic solvent used is ethanol. 3. An improved as claimed in claim 1, wherein the ratio of alcohol to water in a mixture of alcohol and water is 1:1. 4. An improved as claimed in claim 1, wherein the current density used in electrolysis reaction in step (b) is preferably in the range of 30-100 A/m2 in the absence of cobalt additive. 5. An improved as claimed in claim 1 wherein the current density used in step(b) is in the range of 200-220 A/m2 in the presence of cobalt additive. 6. An improved as claimed in claims 1, 4 & 5 wherein the cobalt additive used is cobalt nitrate. 7. An improved as claimed in claims 1,& 4-6 wherein the quantity of cobalt additive used is in the range of 2-3gpl. 8. An improved as claimed in claim 1 wherein the temperature used for drying the green precipitates of nickel hydroxide after washing in step(b) used is in the range of 60-70°C for a period of 40-48 hrs. 9. An improved as claimed in claim 1, wherein the alpha-nickel hydroxide obtained has a discharge capacity in the range of 195-220 mAh/g. 10. An improved single step process for the preparation of battery grey alpha-nickel hydroxide substantially as herein described with reference to the examples.

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