BATTERY CATHODE TO SEA WATER AND PRODUCTION METHOD THEREOF

The present invention relates to the batteries to sea water and, more particularly, a cathode for a battery to sea water and a method for manufacturing the cathode.

Currently, the cathodes in the batteries to sea water are usually produced using such compounds insoluble cuprous chloride (CuCl or), the cuprous iodide (dead end), and the silver chloride (AgCl plating) as active substance, graphite or the like as conductive material, and methods comprising the heat fusing, attaching with a bonding agent, the casting, and molding a conductive metallic bar on, and the anodes are mainly made of magnesium alloy.

The batteries using the conventional cathode such as described above have however some drawbacks. Compounds used as the cathode active material is water insoluble, the batteries have a slow activation upon encounter with water. The performance of batteries in fresh water are not as good as those in seawater. Further, the process of forming mold is relatively inefficient. Storage of these batteries is also difficult under normal conditions and requires drying, seal and full insulation against 1' moisture.

An object of the present invention is to provide a cathode for a battery to sea water to release the battery problems related to slow activation upon encounter with water and a lower outlet in fresh water such noted in the batteries to existing sea water.

Another object of the present invention is to provide a method for fabricating such a cathode, for good productivity and stability batch manufacturing of batteries to sea water, and preservation of such batteries to sea water under normal conditions without contact with the water, will eliminate the need for drying and sealing.

The present invention implements the following solutions for achieving the objects above.

A cathode for a battery to the seawater is manufactured by using a mixture of copper sulfate monohydrate and anhydrous copper sulfate as an active material, to a mass percentage of 70 - 92%; using conductive carbon powder and carbon fiber conductive as conductive material, the conductive carbon powder having a weight percentage of 1 - 10% and the carbon fiber conductor having a weight percentage of 1 - 10%; by using powder of polyethylene and the polyethylene wax as the bonding agent, the powder PE a mass percentage of 3 - 15% and the wax PE a mass percentage of 3 - 12%; and using a titanium sheet metal or a nickel foil as a current collecting electrode.

Further, the mixture of copper sulfate monohydrate (CuSCq-to-fhO) and anhydrous cupric sulfate (CuSCq) can be performed by heating the copper sulfate pentahydrate (CuSCq-to-SfhO) for at least 3 hours between 250 and 150 °c⁰ C..

Further, the conductive carbon powder may have a size larger than that corresponding to a screen mesh size of 300.

Further, the conductive carbon fiber may have a ratio between the length and the diameter of greater than 20.

Further, the polyethylene powder (powder PEs) may have a size greater than that corresponding to a screen mesh of 30.

Further, the polyethylene wax (PE-wax) may have a size greater than that corresponding to a screen mesh of 30.

Further, the titanium sheet metal or nickel foil can have a thickness of less than 0.5 mm, and a width ratio with respect to the cathode of 0, 0.9 5:1 to 1:1.

A method for manufacturing a cathode for a battery to seawater comprises the following steps:

(1) heating the copper sulfate pentahydrate for at least 3 hours between 150 °c and 250 °c to produce a mixture of copper sulfate monohydrate and anhydrous cupric sulfate; and

(2) mixing the copper sulfate monohydrate and anhydrous cupric sulfate to a mass percentage of 70 - 92% with conductive carbon powder to a weight percentage of 1 - 10%, of the carbon fiber conductive at a weight percentage of 1 - 10%, polyethylene powder PE through a mass percentage of 3 - 15%, and the polyethylene wax to a percentage by weight of 3 - 12% until homogeneous, and transforming the homogeneous material into balls by heating, pressurizing and cuts; placing the electrode sheets of titanium metal or nickel at the center of a cavity of a mold;

injecting the balls of the cathode in the mold by providing within the electrode sheet titanium or nickel by an injection screw, and demolding and cooling to obtain the cathode.

In the aforesaid planes of the present invention, copper sulfate is an electrolyte strong and highly water soluble. When dissolved in fresh water or purified, it can not only improve performance electrolytic battery, but well responsive chemically with magnesium metal in the anode to generate electricity efficiently. It is to this end that the present invention uses copper sulfate as the cathode active material. However, the normally exists as copper sulfate pentahydrate copper sulfate in the form of blue crystals like sand, less transformable and less prone to admixture with either the conductive material, the conductor and the binding agent. To solve this problem, the present invention provides the step of heating the copper sulfate pentahydrate for at least 3 hours between 150 °c and 250 °c to produce a powder mixture of copper sulfate monohydrate and anhydrous cupric sulfate. Copper sulfate monohydrate and anhydrous cupric sulfate can be stored under normal conditions without special cover. Even in the presence of substantial moisture, they can only generate copper sulfate pentahydrate. According to the present invention, copper sulfate, copper sulfate monohydrate and copper sulfate pentahydrate are all active substances for the cathode.

The carbon powder and the carbon fiber conductive are both used as conductive material. The mixture of the two in a specific proportion not only strengthens the conductivity of the cathode block, but also improves the strength and physical properties of the cathode block. The conductive carbon powder can be thoroughly mixed with the active substance and the binding agent to provide the proper conductivity of the cathode block. The carbon fiber is added for the conduction of electricity and to form the network structure, thereby improving the strength of the cathode block and increasing deviations. The cathode blocks for the batteries to sea water being transformed and formed by high temperature and high pressure, they are invariably in the quenched state. When the battery meets water for reaction, the cathode block in state of constructing can slow the release of drugs and even lead to internal obstruction which interrupts the reaction. By adding carbon fiber, the reagent continues differences low even by high temperature and high pressure, thus ensuring a complete reaction of the active material of the cathode.

By adding the polyethylene resin in the polyethylene wax as the bonding agent, the fluidity of materials during processing of the cathode block can be improved, and the formation pressure reduced.

The titanium sheet metal and nickel foil electrodes are used as both corrosion and oxidation, the titanium sheet is particularly preferred. By making the electrode sheet, the contact area with the cathode block is increased, thereby enhancing the effect of sinking current compared to a column electrode.

Specific embodiments will be described below to illustrate the present invention in detail.

A cathode for a battery to the seawater is manufactured by using a mixture of copper sulfate monohydrate (cus0₄ - HR₂ 0) and anhydrous cupric sulfate (cus0₄ ) as an active material, a mass percentage of 70 - 92%. The mixture of copper sulfate monohydrate (cus0₄ - HR₂ 0) and anhydrous cupric sulfate (cus0₄ ) is performed by heating the copper sulfate pentahydrate (cus0₄ - 5:00₂ 0) for at least 3 hours between 150 °c and 250 °c.

The conductive carbon powder and the conductive carbon fiber are used as conductive materials, each at a weight percentage of 1 - 10%. The conductive carbon powder has a size larger than that corresponding to a screen mesh size of 300. The conductive carbon fiber has a ratio of length to diameter greater than 20.

The polyethylene powder and the polyethylene wax are used as binding agent, have a mass percentage of 3 - 15% and 3 - 12%, respectively. The polyethylene powder (powder PEs) and the polyethylene wax (wax PEs) both have a size greater than that corresponding to a screen mesh of 30.

A titanium sheet metal or a sheet of nickel is used as a current collecting electrode. The titanium sheet metal or nickel has a thickness of less than 0.5 mm, and a width ratio with respect to the cathode of 0, 0.9 5:1 to 1:1. The mass in the cathode of the titanium sheet metal or nickel as the current collecting electrode is small enough to be neglected.

A method for manufacturing a cathode for a battery to seawater comprises the following steps:

(1) heating the copper sulfate pentahydrate (cus0₄ - 5:00₂ 0) for at least 3 hours between 150 °c and 250 °c to produce a mixture of copper sulfate monohydrate (cus0₄ - HR₂ 0) and anhydrous cupric sulfate (cus0₄ );

(2) mixing the copper sulfate monohydrate (cus0₄ - HR₂ 0) and anhydrous cupric sulfate (cus0₄ ) to a weight percentage of 70 - 92% with conductive carbon powder to a weight percentage of 1 - 10%, of the carbon fiber conductive at a weight percentage of 1 - 10%, polyethylene powder PE through a mass percentage of 3 - 15%, and the polyethylene wax to a percentage by weight of 3 - 12% until homogeneous, and transforming the homogeneous material into balls by heating, pressurizing and cuts; placing the electrode sheets of titanium metal or nickel at the center of a cavity of a mold;

injecting the balls of the cathode in the mold by providing within the electrode sheet titanium or nickel by an injection screw, and demolding and cooling to obtain the cathode.

The present invention uses the water-soluble compound of copper sulfate. Compared to the batteries to conventional sea water, the battery using the cathode described behaves much better in fresh water and purified water. It has been found during testing that the battery to sea water of the present invention has a difference of 30% discharge less than when placed in sea water, fresh water and purified water.

The present invention utilizes the plastic injection so as to improve the efficiency and uniformity of the production compared to conventional treatment using hot melting, casting and molding.

Using both carbon powder and carbon fiber as a conductive material, the present invention provides an improved conductivity and physical strength reinforced of the battery. On the other hand, the lattice structure of the carbon fiber helps prevent the cathode block state for quenched.

Unlike conventional batteries requiring drying and sealing for storage, the battery to seawater described requires only avoiding contact with water prior to 1' use.

The present invention has been described with respect to preferred embodiments and it is understood that the embodiments are not intended to limit the scope of the present invention.