key: cord-0047310-vcsq0630 authors: Orazem, Mark E. title: Editorial Overview: Electrochemical Engineering If chemists make chemicals and chemical engineers make money, what do electrochemical engineers do? date: 2020-07-09 journal: Curr Opin Electrochem DOI: 10.1016/j.coelec.2020.06.008 sha: 32157bd0c27386e779f4c41a37f75844da232126 doc_id: 47310 cord_uid: vcsq0630 nan In 1962, Carl Wagner 1 described the connection between electrochemical engineering and chemical engineering, observing that "the problem of mass transfer in electrolytic cells is closely related to problems of mass and heat transfer encountered in general chemical engineering." He observed further that "the problem of current distribution in electrolytic cells has no direct analogy in general chemical engineering." Wagner stated that "problems of mass transfer and of current distribution are basic to the science of electrochemical engineering, which supplements the older art of electrochemical engineering (emphasis mine)." Hartmut Wendt and Gerhard Kreysa 2 suggest that Carl Wagner, along with Charles W. Tobias, Fumio Hine, and Norbert Ibl, may be considered to be a founder of electrochemical engineering science. Both electrochemical engineering and chemical engineering can be described as the confluence of three basic fields of learning: mathematics, physics, and chemistry. In the preface to their book, John Newman and Karen Thomas-Alyea 3 found that the "science of electrochemistry is both fascinating and challenging because of the interaction among thermodynamic, kinetic, and transport effects." Wendt and Kreysa 2 argue that electrochemical engineering science is a discipline that deals with electrochemical systems and processes according to scientific principles, finding its place between chemical engineering and electrochemistry. As chemical engineering researchers have migrated from optimizing chemical plants to studying applied science, electrochemical engineering researchers have moved from supporting electrochemical production of commodity chemicals to applying electrochemical engineering science to devices and concepts of modern interest. The papers represented in this section provide an overview of the nature of work done by elec-trochemical engineering researchers. These range from applications of new transfer-function methods to electrochemical systems, to catalyst design and degradation, to multi-functional films and membranes, to the challenge imposed by Industry 4.0, the current trend of automation and data exchange in manufacturing technologies. Shirsath et al. 4 describe a new type of transfer function for polymer-electrolyte (PEM) fuel cells called electrochemical pressure impedance spectroscopy in which the back pressure in a PEM fuel cell is modulated and the effect on cell voltage is measured. This type of transfer function is applicable at low frequencies, and the authors suggest application for frequencies below 1 Hz. Experimental results are shown for a frequency range extending from 1 mHz to 1 Hz. Nara et al. 5 emphasize electrochemical impedance spectroscopy for on-board application in lithium batteries. Their review covers impedance spectroscopy models used for the interpretation of lithium-ion batteries from advanced equivalent circuit models to a detailed mathematical description developed by John Newman. They describe their own contributions to on-board diagnostics of battery packs, achieved by use of an input signal generated by a power controller in a battery management system instead of the conventionally-used frequency-response analyzer. They suggest that the coupling of on-board impedance spectroscopy with machine learning of impedance data may enhance battery safety. Gharbi et al. 6 provide a perspective on local electrochemical impedance spectroscopy. They observe that the ability to probe surface reactivity on a local scale has contributed new insight concerning electrochemical reactivity in relation with the microstructure of the surface. Local electrochemical impedance spectroscopy has the advantage of using a transient approach to locally characterize a stationary electrochemical system without the need to add any redox mediator in solution, which is a great advantage for the study of different systems. Perry et al. 7 provide a review of catalyst materials and cell designs for carbon dioxide reduction as used for electrosynthesis, energy storage applications, and environmental remediation. The catalysts considered include pure metals, alloys, and micro-/nano-structured materials. They argue that the next advancements in the field will come from meeting the requirements to scale-up the laboratory-scale reactor operations to industrially relevant standards. Faradaic efficiencies towards a specific product tend to fall as the current density increases, due to the increased hydrogen-evolution at larger current densities. They identify a need for catalyst materials, innovative supports, and reactor designs that inhibit water reduction. Prokop et al. 8 review the degradation of Pt-based catalyst in PEM fuel cells. They describe degradation mechanisms inferred from experimental measurements and show how mathematical modeling may be used to predict the extent of degradation. Prokop et al.conclude that degradation of the catalyst during PEM fuel cell operation remains one of the issues preventing widespread commercialisation of this technology. The intensity of the degradation processes is strongly dependent on operating conditions and, consequently, experimental investigation must be tailored to each type of PEM fuel cell. Mathematical models have made a significant contribution to the prediction of fuel cell lifetime, but these models still focus on a restricted range of conditions, limiting their validity. Luiso and Fedkiw 9 provide an overview of new developments in the materials used as lithium-ion battery separators, essential in cell design due to its influence on energy and power densities, safety and cycle life. In this review, they highlighted new trends and requirements of state-of-art Li ion battery separators. Multi-functional separators offer a new range of possibilities when chemically active functional groups are incorporated in the separator, providing additional features in terms of safety and performance. By nanoengineering the material network in a multi-functional separator, the authors argue that they would be able to create preferred pathways for ion transport in 3D structures that maximize both the Li ion motion and safety while reducing degradation. Walsh et al. 10 review electrodeposition of coatings produced by incorporating particles into an electrodeposit. Electrochemical approaches to the deposition of composite coatings offer the benefits of good control over deposition rate and film thickness, coating composition, and deposit properties. Both faradaic electrodeposition and electrophoresis may be involved. The authors indicate that the electrodeposition of metallic, ceramic, or polymeric particles embedded in a metal matrix has become a mature technology which continues to evolve and diversify. They argue that future research should emphasize characterization of particle dispersions, search for combinations of particle types and sizes to achieve specific design aims, enhanced cell designs, better understanding of electrodeposition mechanisms, and improved computational models with attention to industrial processing and scale-up. Roy and Andreou 11 provide a perspective on how electrochemical engineering may enter the Industry 4.0 Era in which big data and automation will require precise knowledge that allows control, monitoring, and prediction for a process. They use electroforming as an example and identify the unresolved issues that currently limit the application of big data. The differences between cathodic reactions in sulphamates and sulphates, ambiguities related to the role of boric acid, and paucity of data on anode reactions are highlighted. The scope of electrochemical engineering Electrochemical Engineering: Science and Technology in Chemical and Other Industries Electrochemical pressure impedance spectroscopy for investigation of mass transfer inpolymer electrolyte membrane fuel cells Technology of electrochemical impedance spectroscopy for an energysustainable society Local electrochemical impedance spectroscopy: A window into heterogeneous interfaces Developments on carbon dioxide reduction: Their promise, achievements and challenges Review of the experimental study and prediction of Pt-based catalyst degradation during PEM fuel cell operation Li-ion battery separators: Recent developments and state-of-art The electrodeposition of composite coatings: Diversity, applications and challenges Electroforming in the industry 4.0 era, Current Opinion in Electrochemistry The authors highlighted in this special issue provide examples of the diverse field of electrochemical engineering. Their work encompasses fuel cells, batteries, development of new measurement technologies, carbon dioxide reduction, electrodeposition of composite films, and electroforming. In the tradition of Carl Wagner, the authors represented in this special issue are expanding the horizons of electrochemical engineering science, cementing the definition of electrochemical engineering as the confluence of mathematics, physics, and electrochemistry.