The Electrochemical Performance Of Silver Oxide Electrodes About Zinc Silver Oxide Reserve Batteries

Zinc-silver oxide batteries have the advantages of high specific energy and power, with safety and stable discharging voltage, especially with the large discharging rate. Therefor the zinc-silver oxide batteries are developed rapidly in the past century. However, the high price of zinc-silver oxide batteries confines its usage in aerospace and military field, where the cost is careless. With the development of military, the zinc-silver oxide reserve batteries is required to have better electrochemical performance, among which the storage life should be longer than 10 years. The silver electrode is the mainly fator for its importance in the batteries.In recent years, the study of the pressed silver electrodes, which may improve the storage life, is the research focus in the zinc-silver oxide reserve batteries. Compared with the sintered silver electrodes, the pressed silver electrodes, though is controlled for its current collector, show the outstanding advantages. But few researches have been carried out in our country.In view of this, the AgO electrodes have been prepared by potassium persulfate oxidation and silver-coated nickel foam method. The foamed silver electrode has been prepared as the following: degreasing, coarsening, sensitization, activation, chemical plating, electroplating, burning and reducing and sintering the foamed silver electrode. The AgO is used as active on the foamed nickel susbstrate in imidazole-sulfosalicylic acid silver electroplating bath. Upon the AgO, the foamed silver, foamed nickel and silver-coated nickel foam is used as current collector respectively, then the discharging performance of pressed silver electrodes has been studied.Firstly, the discharging performance of pressed silver electrodes with the foamed silver as current collector has been discussed. The discharging performance of the silver electrode is the best when AgO is used as active substance under the 45MPa pressure. The average discharging voltage and capacity are the highest. There is no high voltage platform for the silver electrode discharged at 2mA·cm^-2. When the current density was 100mA·cm^-2, the discharging capacity is 381.6mAh·g^-1. The discharging performance of the pressed silver electrode is better than that of the sintered silver electrode. When the Ag₂O is used as active substance, the utilization of Ag₂O is very high. Even when discharged at 100mA·cm^-2, the utilization of Ag₂O could achieve 93.6%, but there was voltage valley at the moment of discharge.Additionally, the discharging performance of pressed silver electrodes, with the foamed nickel as current collector has been researched. The discharging performance of the silver electrode is the best when AgO is used as active substance under the pressure of 45MPa. The average discharging voltage and capacity are the highest. When discharging at 100mA·cm^-2 for the silver electrode, the discharging capacity is 374.9mAh·g^-1 respectively. However, a high-voltage platform and a voltage valley appears during discharging process, therefore making it unsuitable for the foamed nickel was not suitable as current collector of silver electrodes.Finally, the discharging performance of pressed silver electrodes with the silver-coated nickel foam as current collector has been researched. The silver-coated nickel foam electrode shows the best performance. The silver particle is well adhered to the foam nickel after electroplating for 20min and sintered for 25min at 450℃, with the protection of the gas mixture of argon-hydrogen. There was no high voltage platform for the silver electrode discharged at 2mA·cm^-2. The discharging capacity is 381.4mAh·g^-1 when the current density is 100mA·cm^-2, without any voltage valley during discharging process. This indicates that the silver-coated nickel foam can replace the foamed silver as the promising current collector.