Nano-sized MnO2 particles produced by spray pyrolysis for a Zn/MnO2 primary cell: comparative discharge performance studies with their bulk counterparts

Abstract

In this work, nano-sized spherical MnO₂ particles with large surface area were synthesized employing spray pyrolysis for application in a Zn/MnO₂ primary cell. Furthermore, we experimentally investigated the performance of nano-sized MnO₂ particles when mixed with conductive additives, such as graphite and Vulcan carbon. The effect of particle size on the discharge performance of cells using two electrolytes (ZnCl₂ and Zn(O₂CCH₃)₂) was examined. To determine the crystalline phase, we comprehensively characterized microstructure, purity, particle size, thermal stability and surface area of both bulk and nano-sized particles. The measurements of electrochemical discharge characteristics, such as constant current discharge, cell capacity and internal resistance, were performed. From these discharge measurements, the nano-sized particle-based cathode (nano-sized MnO₂/Vulcan carbon) discharge capacity was found to be 303 mA h g⁻¹, which is 128% higher than the maximum value of the bulk MnO₂ counterpart-based cathodes (bulk MnO₂/Vulcan carbon). In addition, the internal resistance of the nano-sized MnO₂/Vulcan carbon cathode-based cell appeared to be very low compared to that of all other bulk cathodes. Our results show that the configuration of nanoparticle-based cathode cells allows them to exhibit superior discharge capacity retention and increased shelf life compared to the conventional Zn/MnO₂ cathode cells.