Electrolysis: processes – compositions used therein – and methods – Electrolytic synthesis – Preparing inorganic compound
Reexamination Certificate
1998-12-21
2001-04-10
Gorgos, Kathryn (Department: 1741)
Electrolysis: processes, compositions used therein, and methods
Electrolytic synthesis
Preparing inorganic compound
C205S333000, C205S539000, C205S542000
Reexamination Certificate
active
06214198
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to electrolytic manganese dioxide for use as the cathode in batteries and methods of producing the electrolytic manganese dioxide. More particularly, the present invention provides electrolytic manganese dioxide which when utilized in batteries imparts higher discharge capacity at high discharge rates thereto.
2. Description of the Prior Art
Electrolytic manganese dioxide, referred to in the industry as EMD, is widely used as the cathode material in batteries. EMD was first utilized in zinc-carbon cells (Leclanche cells), and later in alkaline cells.
EMD is used in alkaline batteries to achieve high voltages, low polarization and high discharge capacities. The discharge capacity of alkaline batteries is dependent upon the quality of the EMD utilized. The mixture forming the cathode in alkaline batteries is about 82% EMD and is generally formed into an annular cathode by impact extrusion in the container or by the compression molding of pellets which are recompacted against the container. In both of these processes, the properties of the EMD must be very consistent to allow the battery manufacturer to consistently produce high quality batteries. Alkaline batteries have a higher capacity per unit volume than other zinc-manganese dioxide batteries, and are particularly capable of high discharge capacity, i.e., long life, at high discharge rates.
To achieve the EMD purity required in its production utilizing the well known electrolysis method, a highly purified manganese sulfate solution must be provided to the electrolytic cell. In addition, the electrolytic cell must be operated within a narrow range of process conditions.
By the end of the 1980's, EMD was developed having what was thought to be a satisfactory discharge capacity at the then maximum discharge rates demanded by portable devices, i.e., about 0.5 watt. However, during the past several years, the development of lap-top computers, video cameras, cellular phones and the like have brought about a demand for high discharge capacity at higher discharge rates, i.e., from 1 to 2 watts. While some improvements in battery performance at high discharge rates have been made, EMD has not changed significantly in discharge capacity or in the process conditions utilized in its production for many years. Thus, there is a continuing need for better, higher quality EMD whereby alkaline and other batteries utilizing the EMD have higher discharge capacities at the higher discharge rates presently required.
SUMMARY OF THE INVENTION
The present invention provides improved high quality EMD for use as cathode material in batteries of high discharge capacity at high discharge rates and methods of producing such EMD by electro-deposition in an electrolytic cell. The electrolytic cell includes cathodic and anodic electrodes disposed therein through which an electric current is passed. In accordance with the methods of the present invention, a heated aqueous electrolyte solution comprising sulfuric acid and manganese sulfate is maintained in the electrolytic cell. The solution is of high purity and includes manganese sulfate therein in an amount whereby manganese is present in the range of from about 5 to about 50 grams of manganese per liter of solution. An electric current is applied to the cathodic and anodic electrodes and the electrolyte solution whereby the anodic electrode current density is in the range of from about 2.5 to about 6 amperes per square foot, and the high discharge capacity EMD produced is deposited on the anode.
The temperature of the electrolyte solution in the electrolytic cell is carefully maintained in the range of from about 95° C. to about 98° C. Also, the sulfuric acid concentration in the electrolyte solution is maintained in an amount in the range of from about 20 to about 50 grams of sulfuric acid per liter of solution.
The cathode utilized in the electrolytic cell is preferably comprised of copper, graphite or steel, as determined by cost. The anode is preferably comprised of titanium to provide minimum weight and volume, maximum strength, minimum weight loss, and adequate corrosion resistance.
It is, therefore, a general object of the present invention to provide improved electrolytic manganese dioxide having higher discharge capacity at high discharge rates and methods of producing the same.
Other and further objects, features and advantages of the present invention will be readily apparent to those skilled in the art upon a reading of the description of preferred embodiments which follows.
REFERENCES:
patent: 3855088 (1974-12-01), Kosaka
patent: 3900385 (1975-08-01), Era et al.
patent: 3951765 (1976-04-01), Everett
patent: 4069116 (1978-01-01), Dzhaparidze et al.
patent: 4477320 (1984-10-01), Riggs, Jr.
patent: 4483828 (1984-11-01), Laughlin et al.
patent: 4485073 (1984-11-01), Robertson et al.
patent: 4489043 (1984-12-01), Bowerman et al.
patent: 4606804 (1986-08-01), Schulke et al.
patent: 4744878 (1988-05-01), Riggs, Jr.
patent: 5489493 (1996-02-01), Urry
patent: 5746902 (1998-05-01), Takehara et al.
Text literature from Chapter 3 entitled Electrochemistry of Manganese Dioxide and Production and Properties of Electrolytic Manganese Dioxide (EMD) by A. Kozawa published inBatteries, vol. 1 (1974). Month of publication not available.
Publication entitled How the Solid State Properties of Electrodeposited Manganese Dioxide Correlate With the Conditions of its Deposition by E. Preisler published inThe 2nd Battery Material Symposium(The 3rd MnO2Symposium), vol. 2, Graz, pp. 247-266 (1985). Month of publication not available.
Publication entitled Electrochemical Procedure in Electrical Generation, Electrical Storage and Electrical Distribution by E. Preisler et al. published inDECHEMA Monogr., 109, pp. 123-137 (1987). Month of publication not available.
Publication entitled Material Problems Encountered in Anodic MnO2Deposition by E. Preisler published inJournal of Applied Electrochemistry, vol. 19, pp. 559-565 (1989). Month of publication not available.
Publication entitled Pilot Plant Studies for the Production of Electrolytic Manganese Dioxide and Managanese Metal by P. Sen Gupta published inProceedings of the International Symposium on Electrometallurgical Plant Practice, pp. 141-161 (1990). Month of publication not available.
Publication entitled Alkaline Discharge Testing of EMD Samples in Plastic Cells by S.F. Burkhardt, published inProgress in Batteries&Battery Materials, vol. 11, IBA Sydney, Australia Meeting, pp. 136-149 (1992). Month of publication not available.
Publication entitled Effect of Some EMD Structural Features on Alkaline Discharge Capacity by T.N. Andersen published inProgress in Batteries&Battery Materials, vol. 11, IBA Sydney, Australia Meeting, pp. 105-129 (1992). Month of publication not available.
Publication entitled The Influence of Potassium Ion on the Electrodeposition and Electrochemistry of Electrolytic Manganese Dioxide by W-H. Kao et al. published inJournal of the Electrochemical Society, vol. 139, No. 5, May, 1992, pp. 1223-1226.
Publication entitled Electrolytic Manganese Dioxide Quality Management, A Case Study by R.F. Wohletz et al. published inProceedings of the Symposium on Quality Management in Industrial Electrochemistryby The Electrochemical Society, Inc., Proceedings vol. 93-19, pp. 49-59 (1993). Month of publication not available.
Publication entitled Effect of Deposition Conditions on the Structural, Chemical, Physical and Electrochemical Properties of EMD by R. Williams et al. published inProgress in Battery&Battery Materials, vol. 13, pp. 102-112 (1994). Month of publication not available.
Publication entitled High Drain Discharge Performance of EMD by R.P. Williams et al. published inProgress in Batteries&Battery Materials, vol. 15, pp. 48-56 (1996). Month of publication not available.
Ph.D. thesis entitled The Effect of Operating Parameters on the Properties of Electrolytic Manganese Dioxide by M. Mauthoor, University of the Witwatersrand, Johannesburg, South Africa (1
Andersen Terrell Neils
Burkhardt Samuel Faust
Howard, Jr. Wilmont Frederick
Kazerooni Vahid
Moumenzadeh Mohammad Reza
Dougherty, Jr. C. Clark
Gorgos Kathryn
Kerr-McGee Chemical LLC
Leader William T.
LandOfFree
Method of producing high discharge capacity electrolytic... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method of producing high discharge capacity electrolytic..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method of producing high discharge capacity electrolytic... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2550415