Metal-air batteries are becoming of particular interest, from both fundamental and industrial viewpoints, for their high specific energy density compared to other energy storage devices, in particular the Li-ion systems. Among metal-air batteries, the zinc-air option represents a safe, environmentally friendly and potentially cheap and simple way to store and deliver electrical energy for both portable and stationary devices as well as for electric vehicles. Zinc-air batteries can be classified into primary (including also the mechanically rechargeable), electrically rechargeable (secondary), and fuel cells. Research on primary zinc-air batteries is well consolidated since many years. On the contrary, research on the electrically rechargeable ones still requires further efforts to overcome materials science and electrochemical issues related to charge and discharge processes. In addition, zinc-air fuel cells are also of great potential interest for smart grid energy storage and production. This review aims to report on the latest progresses and state-of-the-art of primary, secondary and mechanically rechargeable zinc-air batteries, and zinc-air fuel cells. In particular, this review focuses on the critical aspects of materials science, engineering, electrochemistry and mathematical modeling related to all zinc-air systems.

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In this paper, we investigate from a theoretical point of view the 2D reaction-diffusion system for electrodeposition coupling morphology and surface chemistry, presented and experimentally validated in Bozzini et al. (2013 J. Solid State Electr. 17, 467-479). We analyse the mechanisms responsible for spatio-temporal organization. As a first step, spatially uniform dynamics is discussed and the occurrence of a supercritical Hopf bifurcation for the local kinetics is proved. In the spatial case, initiation of morphological patterns induced by diffusion is shown to occur in a suitable region of the parameter space. The intriguing interplay between Hopf and Turing instability is also considered, by investigating the spatio-temporal behaviour of the system in the neighbourhood of the codimensiontwo Turing-Hopf bifurcation point. An ADI (Alternating Direction Implicit) scheme based on high-order finite differences in space is applied to obtain numerical approximations of Turing patterns at the steady state and for the simulation of the oscillating Turing-Hopf dynamics.

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We focus on the morphochemical reaction-diffusion model introduced in Bozzini et al. (2013) and carry out a nonlinear bifurcation analysis with the aim to characterize the shape and the amplitude of the patterns arising as the result of Turing instability of the physically relevant equilibrium. We perform a weakly nonlinear multiple scales analysis, and derive the normal form equations governing the amplitude of the patterns. These amplitude equations allow us to construct relevant solutions of the model equations and reveal the presence of multiple branches of stable solutions arising as the result of subcritical bifurcations. Hysteretic type phenomena are highlighted also through numerical simulations. We show the occurrence of spatial pattern propagation and derive the Ginzburg-Landau equation describing the envelope of the traveling wavefront

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In this paper we report on the reactivity of adsorbed cyanide deriving from ligand release during metal electrodeposition from cyanocomplex solutions of Au(I), Au(III), Ag(I) and Cu(I) in H 2 O and D 2 O. When CN¯ is adsorbed at cathodic potentials in excess of the HER threshold, metal-dependent reactivity can be detected by SERS. Finite surface coverages with adsorbed CN¯ at such cathodic potentials can be obtained only if CN¯ is delivered directly to the cathode surface as by decomplexing of the cyanocomplexes of the metals undergoing cathodic reduction. In Au(I) and Au(III) baths, Au-CN¯ reacts with Au-H• and is hydrogenated to adsorbed CH 2 =NH and CH 3 -NH 2 .In Ag(I) baths, Ag-CN¯ reacts with Ag-H • giving rise to polycyanogens. No reactivity of Cu-CN¯ was found, under otherwise identical conditions. Our conclusions are supported also by dedicated DFT molecular computations.