Effect of Silver (П) oxide Particle Size on Discharge Characterization of Cathode for Alkaline Battery

Silver (П) oxide (AgO) is used as a cathode material in a variety of alkaline batteries [1]. This cathode material is widely used in space and military industries due to their high energy density, capacities and average voltage [2]. The properties of the cathode discharge are one of the most important functional properties of the battery and depend on various factors such as porosity, surface area and capacity of active material, the conductivity of the adhesive and active material system, and other factors [3,4]. In various studies, the electrochemical properties and conductivity of cathodes based on AgO have been investigated, but the effect of particle size distribution on the properties of the cathode discharge has not been considered. In this research, AgO particles were synthesized by oxidation of silver nitrate with potassium persulfate in an alkaline medium. The five samples of AgO active material were synthesized in various concentration and synthesis condition. Then, characterization and discharge properties of the AgO material were investigated. SEM micrographs show that all synthesized particles are in the form of a plate, and the difference between particles is due to differences in particle size and particle size distribution (Table 1). The synthesized AgO samples 3 and 4 have the smallest average length size and narrowest particle distribution (0.05-0.3μm). The widest range of particle size is for the sample 5, which is a mixture of fine particles of 0.1 μm and large particles of 4.5 μm. Figure 1 shows the discharge curves of the synthesized AgO cathodes at a current density of 0.2 A/cm2. The results show that the highest output voltage (1.78 V) and the lowest voltage drop is observed for sample 5. Also, this sample cathode provides a flatter discharge profile than other samples. The reason for these outstanding properties can be seen in improving the cathode conductivity and the silver product formed in the second step of discharging. Table 1 shows the results of particle size and the capacity values of the synthesized samples. The 13th Annual Electrochemistry Seminar of Iran Materials and Energy Research Center (MERC), 22- 23 Nov, 2017 124 results show that the sample 5 has the highest capacity (0.3 Ah.g−1, and 0.46 Wh.g−1, respectively) in between samples. This value is about 1.5 times the capacity of sample 1 (0.18 Ah.g−1 and 0.27 Wh.g−1). The sample 5 has a mixture of fine and large particles, which increase the connection between particles, decrease interconnections and creates a path for conduction in the cathode with the lowest contact resistance, while in samples 3 and 4, there are a large number of particles in the nanometer range that whose interconnections lead to increased contact resistance and reduced number of conduction paths in the cathode and therefore have finite conduction properties.