Elctro-depositon Of The Foam Silver And Research Of Its Application Used As Anode Current Collector Of The Zinc Silver Battery

Zinc-silver batteries have been commonly used in national defense products becauseof its high specific capacity, remarkable power density, and stable output voltage, as wellas reliable security, especially commonly used as reserve batteries in military, such asstart power of the rockets, missiles, submarines and satellites.With the modernization of the militaries and aircrafts, we need more advancedzinc-silver batteries with higher specific capacity and power density. And the zinc anodeis of vital importance to the integral performance of the batteries. Foam silver, due to its3D highly porous structure, is very promising to enhance the zinc electrode performancewhen used as the current collector.In this paper, we firstly studied the fabrication process of foam silver, includingpretreatment, conductive treatment, electro-deposition, burning and reduction on thesubstrate of polyurethane foam, and obtained highly porous foam silver with structureintegrity. Secondly, we invested the function of the foam silver when used as the zincelectrode current collector, as well as the function of CMC used as the electrode addition.We firstly compared two different kinds of conductive treatment methods: coatingwith electrically conductive slurry, and megnetron sputtering nickel. Results revealed thatmegnetron sputtering nickel is a better way to get conductive foam with high porosityand conductivity, which is beneficial to produce high-quality foam silver. On the basis ofthat, we optimized the electro-deposition conditions of the foam silver, and obtainedoptimum conditions:AgNO3(24g/L), current density (1.75A/dm2), temperature (25℃)，pH(9). Under such conditions, we got foam silver with uniform plating coating andmicropores.Then we use silver foam to substitute traditional silver net as current collector, andtested their discharge performance of corresponding zinc electrodes. By caparison, foamsilver with smaller pore diameter exhibited much better current collect efficiency. Whenthe pore diameter is450μm, the specific discharge capacity of corresponding zincelectrode can reach495mAh/g under3C discharge current, which is41%higher than thesilver net used as traditional current collector, amount to60%of the theoretical specificcapacity of zinc. Additionally, we made different zinc electrodes by using dendriticelectrolytic zinc powder and hybrid zinc powder as active materials, results showed thatdendritic electrolytic zinc powder is not suitable for foam metal-based zinc electrodes,and the fewer active materials loading, the better discharge performance of zinc electrodecan reach. We found CMC, when used as electrode addition, can restrain the positivepassivation at some certain extent, but no obvious inhibition to the corrosion properties,and no obvious enhancement to the discharge specific capacity. Finally we studied the effect of extra pressure on the electrodes performance, the results showed that extrapressure enlarged the electrode impedance, which resulted worse discharge performance.