February 2018

Do we always get ZnO as discharge product in electrically rechargeable zinc–air batteries? Nowadays, air breathing batteries appear as a good alternative to overcome our increasing demand of energy. One of the best candidates regarding its cost of production, recyclability and safety is the electrically rechargeable Zn/air battery. Therefore, the development of the rechargeable Zn/air battery has attracted much attention and received an intense research effort to extend its cycling stability. One key issue in alkaline electrically rechargeable Zn/air battery is the electrochemical reaction at the Zn electrode. ZnO as discharge product cannot be fully converted to Zn. In general, the formation of ZnO is influenced by many parameters such as local concentration, pH and diffusion of Zn ions species in alkaline solution. However, the nucleation and growth of ZnO in electrically rechargeable Zn/air battery can be also influenced by an interaction between discharge and charge process. We observed that a battery component, such as a Sn current collector, could also affect the nature of the discharge product during cycling. The scanning electron micrograph (figure below) shows orthorhombic ZnSnO3 or Zn2SnO4 crystallites surrounded by many hexagonal tubes of ZnO obtained after 25 cycles on top of the Zn electrode. These new investigations are part of the ongoing German-Japanese BMBF joint project ‘Zisabi’ to gain a deeper insight into electrically rechargeable Zn/air batteries. (Picture submitted by Saustin Dongmo and Daniel Schroeder.)