ORIGINAL PAPER Enhanced zinc corrosion mitigation via a tuned thermal pretreatment in an alkaline solution containing an organic inhibitor D. Gelman 1,2 & H. Drezner 2 & A. Kraytsberg 2 & D. Starosvetsky 2 & Y. Ein-Eli 1,2 Received: 29 September 2017 /Revised: 6 February 2018 /Accepted: 9 February 2018 # Springer-Verlag GmbH Germany, part of Springer Nature 2018 Abstract A short-term exposure of zinc (Zn) electrodes in polyethylene glycol (PEG) containing alkaline electrolytes at a temperature range of 45–65 °C significantly reduces the corrosion rate of the Zn in the strong alkaline solutions. The enhanced characteristics of the protective film formed during this pretreatment process is attributed to a substantial reduction in the cross-sectional Bdiameter^ of the hydrated inhibitor molecules, due to a decrease in the hydration number at warmer temperatures. One can expect that Bslimmer^ organic molecules with a lower cross-sectional dimension, having a lower hydration number, will constitute a denser surface layer, providing enhanced isolation of the neighborhood active sites at the Zn anode. Implementing this approach in alkaline batteries utilizing Zn anodes may result in battery performance enhancement. Keywords Zinc batteries . Corrosion . Inhibiter . PEG . Thermal pretreatment Introduction Zinc (Zn) is one of the most common benign battery electrode materials because of its negative potential, relatively high hy- drogen overvoltage and high specific energy [1–9]. In partic- ular, it is being used as an anode in variety of alkaline batte- ries. However, extensive Zn corrosion in concentrated alkaline solutions and a massive hydrogen evolution remain main chal- lenges to be overcome in these batteries. Thus, mitigating Zn corrosion is an important task in the development of efficient Zn alkaline batteries [3, 4, 6, 10–19]. Overcoming this issue can be via a wise selection of efficient inhibitors that suppress Zn anode degradation, while fulfilling two main requirements: (a) suppression of the cathodic process and (b) allowing the anodic polarization and dissolution of Zn. Importantly, from a Pourbaix diagram (for example, as the one shown in Hoang et al. work [20]), nothing can be deduced on hydrogen evolu- tion, since the pH-potential diagrams are essentially representing a thermodynamic state, while kinetics and the obtained polarization curves (current-potential) determine whether the process would eventually occur. Thus, one cannot discuss hydrogen evolution within a singular aspect, because both the kinetics and overpotential can be easily changed. It was shown that the most efficient inhibitor among the examined materials thus far is polyethylene glycol (PEG with an alkoxide (CO-) anionic head) with a molecular weight of 600 (having ~ 10 repeated oxy-ethylene units, (-O- CH 2 CH 2 ) n = 10 ) and PEG di-acid, being a form of a modified PEG 600, having a carboxylate (COO-) anionic head [21–25]. The efficiency of PEG 600 and PEG di-acid as cor- rosion inhibitors (in the optimal range of 800–2000 ppm [21–25]) is associated with the length of the linear polyoxy- ethylene chain and the active anionic head, serving as a bond- ing site to the zinc-ion [21]. The nano-scale structure of the film formed at the Zn/electrolyte interface plays a crucial role in the suppression of Zn corrosion [26–31]. Thus, an optimal Zn cathodic inhibitor in an alkaline solution should form a dense film that would cover the Zn anode surface and would completely suppress or, at least, minimize the number of ac- tive surface centers available for hydrogen cathodic evolution (Scheme 1). These active surface centers available for hydro- gen cathodic evolution may be simply contaminants present at the Zn surface, but in the case of well-designed Zn alloy Electronic supplementary material The online version of this article (https://doi.org/10.1007/s10008-018-3922-2) contains supplementary material, which is available to authorized users. * Y. Ein-Eli eineli@technion.ac.il 1 The Nancy and Stephen Grand Technion Energy Program, Technion- Israel Institute of Technology, 3200003 Haifa, Israel 2 Department of Materials Science and Engineering, Technion- Israel Institute of Technology, 3200003 Haifa, Israel Journal of Solid State Electrochemistry https://doi.org/10.1007/s10008-018-3922-2