Effects of Additives on Performance of Zinc Air Battery

Abstract

Appropriate energy storage plays a very important role in a wide range of applications, including frequency regulation of renewable energy sources, peak-shaving of electrical grid, emergency power, and portable power. Metal-air batteries have long been a subject of research since they can be used in many applications, such as small batteries for watches, acoustical devices, and as large batteries for electric vehicles. There is a wide variety of applications for zinc metal as high capacity anodic material in the secondary alkaline batteries due to its high specific energy, good reversibility, environmental friendliness, low equilibrium potential, low cost, and no-toxicity. During battery charging, formation of zinc dendritic deposits in alkaline electrolytes severely decreases the cycle life of zinc rechargeable batteries. Uneven current density distribution, local concentration gradient variation, preferential crystalline growth of zinc causes the formation of dendrites. In order to suppress the dendritic growth, many inorganic additives such as CdO, PbO, Pb3O4, In2O3, and Bi2O3 have been tested. To decrease the hydrogen production potential, organic materials also have been studied, such as, poly vinyl alcohol (PVA), triethanolamine (TEA), ethylene-diamine-tetra-acetic acid (EDTA), poly-oxye-thylene sorbitan mono-laurate (Tween 20) and tartaric acid. In this study, the electrochemical behavior of zinc deposition in electrolyte with various additives is investigated by cyclic voltammetry (CV), linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS). The corrosion behavior of zinc in alkaline solution with different additives is also studied. The morphologies and crystalline structures of various Zn deposits are examined by scanning electron microscopy (SEM) and X-ray diffraction (XRD), respectively. We found that zinc dendrite was eliminated by addition of EDTA and Tween 20. Same components can also improve the stability of zinc in alkaline solution. This work was supported by Bureau of Energy, Ministry of Economic Affairs. Key word: zinc dendrite, corrosion, solution additives