Fred
US 5,677,075 Fujita October 14, 1997
"In actual, when water is used as an electrolyte solution to electrolytically oxidize carbon, the pH value of the electrolyte solution shifts to 2 to 3 on the side of acidity. Taking the above fact into consideration, it seems that the original form of acid is carboxylic acid. In case of electrolytic oxidation of carbon, when an electrode made of the carbon material is applied with direct current voltage in water and the currents are gradually intensified, carbon powder is deposited like mist around the positive electrode when the current value exceeds a certain value (the voltage value is variable depending on a distance between the electrodes). The deposited powder suspends in the form of colloid in the water. When electrodes are soaked in the carbon suspension and applied with direct current voltage, the deposited carbon powder is adsorbed on a positive electrode. This electrolytically deposited carbon powder is referred to as electrolytic oxidized carbon powder in t!
he present invention. The above treatment is referred to as treatment of electrolytic oxidation."
"In the embodiment of the present invention, the current value at which the start of dispersion of carbon powder by the electrolysis is visually realized, is called a threshold current value for convenience. (Strictly speaking, it is supposed that the deposition occurs at a smaller current value in such a manner that it cannot be perceived.) The threshold current value varies depending on an area of the carbon positive electrode, a distance between the positive and negative electrodes, the existence of electrolyte or the amount of the electrolyte. In the case where city water is used as the electrolyte solution, when a distance between the positive and negative electrodes is 3 mm or less and an area of the positive electrode is 200 cm.sup.2, the threshold current value is 3 to 5 ampere. "
"Water is preferable as the electrolyte solution for electrolytic oxidizati! on. Water may be used alone, but if necessary, an acidic compo! nent of an electrolyte solution in a battery or another electrolyte such as NACl, LiCl or the like may be added into the water. In case of using pure water as the electrolyte solution, the acidic component of the electrolyte solution or another electrolyte as described above, may be added in to give it conductivity. Water such as city water in which a very small amount of mineral component exists, ensures an appropriate degree of conductivity without adding any substances, so that a desirable carbon powder dispersion liquid can be obtained. The carbon suspension in which electrolytic oxidized powder is dispersed in electrolyte solution is colloidal solution, and is synthesized by electrochemical oxidation. The carbon colloid in the solution acts as a dopant for cathodes in lead-acid batteries. (According to the terminology of electrochemistry, cathodes and anodes are defined as positive and negative electrodes for battery systems, respectively.) The activation of carbon colloid for ! cathodes results in (1) revival of degraded batteries, (2) large charge-currents without any extraordinary increase in temperature, (3) increase in discharge currents and (4) increase in the life time of batteries. In order to describe the details of this invention, the preparation of the carbon colloidal solution is presented below. "
"In the embodiment of the present invention, the current value at which the start of dispersion of carbon powder by the electrolysis is visually realized, is called a threshold current value for convenience. (Strictly speaking, it is supposed that the deposition occurs at a smaller current value in such a manner that it cannot be perceived.) The threshold current value varies depending on an area of the carbon positive electrode, a distance between the positive and negative electrodes, the existence of electrolyte or the amount of the electrolyte. In the case where city water is used as the electrolyte solution, when a distance between the positive and negative electrodes is 3 mm or less and an area of the positive electrode is 200 cm.sup.2, the threshold current value is 3 to 5 ampere. "
"Water is preferable as the electrolyte solution for electrolytic oxidizati! on. Water may be used alone, but if necessary, an acidic compo! nent of an electrolyte solution in a battery or another electrolyte such as NACl, LiCl or the like may be added into the water. In case of using pure water as the electrolyte solution, the acidic component of the electrolyte solution or another electrolyte as described above, may be added in to give it conductivity. Water such as city water in which a very small amount of mineral component exists, ensures an appropriate degree of conductivity without adding any substances, so that a desirable carbon powder dispersion liquid can be obtained. The carbon suspension in which electrolytic oxidized powder is dispersed in electrolyte solution is colloidal solution, and is synthesized by electrochemical oxidation. The carbon colloid in the solution acts as a dopant for cathodes in lead-acid batteries. (According to the terminology of electrochemistry, cathodes and anodes are defined as positive and negative electrodes for battery systems, respectively.) The activation of carbon colloid for ! cathodes results in (1) revival of degraded batteries, (2) large charge-currents without any extraordinary increase in temperature, (3) increase in discharge currents and (4) increase in the life time of batteries. In order to describe the details of this invention, the preparation of the carbon colloidal solution is presented below. "
