US3481786A - Method of making battery electrodes using molten meta-dinitrobenzene - Google Patents

Description

United States Patent 3,481,786 METHOD OF MAKING BATTERY ELECTRODES USING MOLTEN META-DINITROBENZENE Joseph C. Duddy, Trevose, Pa., assignor to ESB Incorporated, a corporation of Delaware No Drawing. Filed Aug. 29, 1967, Ser. No. 663,961 Int. Cl. H01m 15/06, 35/18 US. Cl. 136-67 2 Claims ABSTRACT OF THE DISCLOSURE A battery electrode is made by applying molten metadinitrobenzene (MDB) to a grid. Where thick MDB deposits are desired, a conductor may be added to the molten MDB.

CROSS-REFERENCES TO RELATED APPLICATIONS BACKGROUND OF THE INVENTION The organic compound meta-dinitrobenzene (MDB) is attractive as a depolarizer for a battery electrode due to its high theoretical capacity and comparative low cost.

Prior methods of constructing MDB electrodes have involved pressing a mixture of MDB and a conductor onto a grid. A pressure of from 10,000 to 20,000 psi, applied for a predetermined time period, was required to compress the mixture onto the grid adequately, and when large electrodes were desired this meant that sizeable equipment must be used. Some precaution was necessary to prevent the MDB-conductor mix from breaking away from the grid; paper or some other material was Wrapped around the mixture before pressure was applied to ensure that pressing method is incapable of being used to apply very thin MDB deposits on a grid.

SUMMARY OF THE INVENTION This invention involves applying molten MDB to a grid. Where thick MDB deposits are desired, a conductor may be added to the molten MDB. Large pressures and equipment necessary to produce them are not required No outside wrapper is needed to contain the MDB. This method permits thin deposits of MDB to be applied to grids. The advantages of this method over prior methods are simplicity and lower costs.

DESCRIPTION OF THE PREFERRED EMBODIMENT Meta-dinitrobenzene (MDB) has a sharp melting point (89.6 C.) and is extremely fluid in the molten state.

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Taking advantage of these properties, this invention consists of melting the MDB, applying the molten MDB to a grid, and solidifying or freezing the MDB on the grid.

Any suitable grid may be used on which to deposit the MDB. Grids of expanded nickel or copper are satisfactory.

While the MDB may be heated to any desired temperature above its melting point, it is preferable to hold the temperature of the molten MDB as low as possible to reduce the subsequent freezing time.

The thickness and conductivity desired in the MDB deposit will determine the remainder of the process. Since the MDB has some conductivity of its own, in some instances it might be satisfactory to apply pure MDB to the grid, particularly where a thin deposit is to be applied. To improve conductivity of thicker deposits, however, it is desirable to add a more conductive substance such as finely divided graphite or conductive carbon to the molten MDB; the exact amount of conductor to be added is selected by balancing the desires of increased conductivity and achieving maximum energy density in the MDB- conductor deposit.

The molten MDB or mixture of molten MDB and a conductor may be applied to the grid by any convenient method such as by extruding, molding, casting, or calendering. If a thin MDB deposit is desired, the grid may be dipped in the molten MDB. It is the ease with which the MDB may be applied to the grid that distinguishes this method from those previously used.

To illustrate the utility of an electrode made according to this invention, an electrode having a thickness of 0.025 inch was built by casting and pressing a mixture of molten MDB and graphite into a 3/0 expanded nickel grid; the molten MDB and graphite were present in the ratio of to 30 by Weight. When discharged in seawater against a magnesium anode at a current drain of 20 ma./sq. in., the initial voltage was 0.92 volt per cell and at the end of 4 hours the voltage was 0.83 volt per cell. An electrode made with a copper grid in a similar manner and tested using the same procedure gave a somewhat higher discharge rate.

I claim:

1. The method of making battery electrodes consisting of melting meta-dinitrobenzene, applying the molten meta-dinitrobenzene to a grid, and solidifying the metadinitrobenzene on the grid.

2. The method of claim 1 in which a conductor is added to the meta-dinitrobenzene and the mixture of molten meta-dinitrobenzene and conductor is applied to the grid.

References Cited UNITED STATES PATENTS 2,855,452 10/ 1958 'Morehouse et a1. 3,025,336 3/1962 Bartosh et a1. 3,060,255 10/1962 Lozier.

WINSTON A. DOUGLAS, Primary Examiner A. SKAPARS, Assistant Examiner US. Cl. X.R.