It has been nearly 80 years since David C. Grahame’s review article (Chemical Reviews 41, 441–501, 1947) on the electrical double layer (EDL). This seminal work (with more than 5000 citations) continues to garner substantial interest and serves as an important pedagogical piece for students learning the fundamentals of electrochemistry. At a recent ESC Meeting I had the privilege to listen to yet another talk on the EDL; and so when asked for a topic for a special issue of Interface, I suggested that it be centered around the EDL. Hence, this special issue coedited with Yue Qi highlights important progress in understanding this fundamental subject along with provocation for pursuing remaining questions.
Although the electrical double layer (EDL) is central to electrochemistry, its behavior is far from universal. The transition from metallic to semiconductor electrodes introduces complexities that challenge conventional models and demand new theoretical approaches. This perspective article traces the historical trajectory of these two distinct interfaces, contrasting the electronic and ionic distributions that define their behavior. By examining recent breakthroughs in modeling these disparate systems, we provide a critical outlook on how a deeper understanding of the metal-vssemiconductor dichotomy can propel the design of more efficient electrochemical energy systems.
The electrical double layer (EDL) is central to electrochemistry and has long been defined by charged species, with charge-neutral solvents treated as passive dielectric media in macroscopic models. Decades of advancements in molecular simulations and characterizations have revealed that solvent molecules are structurally and functionally active components of the EDL. Water, in particular, exhibits layering, potential-dependent orientation, and strong coupling with ions. Together, they determine ion distributions, interfacial potential drop, and capacitance. In organic electrolytes, mixed chargeneutral species further introduce complex and tunable interfacial environments that govern electrochemical reactivity and selectivity. Here, we highlight the evolving understanding of charge-neutral species in the EDL and discuss emerging opportunities to design the interfacial structures for energy storage and electrosynthesis.
From the age of the mercury electrode to the era of sustainable development, the landscape of electrochemistry has transformed. Eighty years after David C. Grahame’s monumental review of the electrical double layer, electrochemical devices are no longer adequately modeled by simple planar interfaces, but by nanoporous electrodes and complex electrolytes. This feature article explores the frontier of this evolution, redefining our fundamental understanding of interfacial thermodynamics, reaction kinetics, and ion transport through experimental advances and multiscale modeling. As we look beyond Grahame’s idealized models, the synthesis of theory and experiment offers a new paradigm for engineering the next generation of electrochemical systems for energy storage and chemical transformation.
The correct thermodynamic potential to use for an ensemble depends on the constraints, the quantities that are kept constant. In electrochemical systems the electrode potential is usually kept constant, so the surface tension is the correct potential. However, whether a particular process occurs at constant potential depends on its speed. A single electrochemical reaction step occurs at a timescale of picoseconds, while double-layer relaxation, which would keep the potential at the reaction site constant, takes much longer. Therefore recent attempts to simulate electrochemical reactions at constant potentials do not correspond to the physical reality.
It is my great honor to be the 124th President of The Electrochemical Society. For over 30 years, ECS has been my home society—shaping my career and connecting me with valued colleagues and friends. During my term, I look forward to advancing key priorities, including marking major milestones, helping strengthen the Society’s financial position to ensure its long-term sustainability, expanding global engagement, supporting the next generation of scientists, strengthening connections across academia, industry, and policy, and to moving our mission and serving ECS and its members and staff constructively, collaboratively, and respectfully.
Batteries that simultaneously deliver high energy density and robust safety are essential for advancing electric transportation and sustainable energy systems. All-solid state batteries provide a promising pathway by replacing flammable liquid electrolytes with non-combustible Local Cation Configurations Governing Lithium Diffusion Li3 YCl6 adopts a layered halide structure in which lithium and inorganic solids, while also enabling cell architectures that can enhance energy density at the pack level.
I will venture to say that all of us have fond memories of the playgrounds of our youth. We looked forward to playing with our friends and to meeting new ones. It was a place that promised unbridled joy. We seek to recreate that feeling in our professional lives, but it’s hard. Just as with the playground, you don’t have to be friends with everyone there, you just need to find your crew who agree on the playground rules. Many of us didn’t realize it at the time, but, like our childhood experiences, our early work experiences have a huge impact on how we work and supervise others as we progress in our careers. We either try to replicate what we experienced or try to do the opposite. What we often forget is that not everyone’s experience mirrors our own—and so we get confused when they don’t act like us, which is obviously the best way to act.
The resilience and longevity of metallic infrastructures are increasingly challenged by the growing impacts of climate change, which manifest through complex and evolving environmental stressors. Traditional approaches to corrosion management, which have historically relied on empirical models, periodic inspections, and the extrapolation of historical climate data, are proving insufficient in the context of climate change, including rapidly changing weather conditions. This paper articulates a scientific vision for the future of predictive maintenance and materials selection for metallic structures exposed to dynamic climate regimes. Central to this vision is the development of an integrated digital twin framework that couples high-resolution regional-to-local climate modeling with advanced corrosion prediction methodologies, encompassing both physics-based and data-driven approaches. The digital twin is dynamically updated through an active feedback loop incorporating real-time data from environmental and corrosion sensors, as well as periodic inspection records. In addition, the digital twin framework will be used to understand the consequences of future climate conditions. Designed to operate at spatial resolutions down to a few kilometers, the system enables site-specific risk assessments and supports informed decision-making for both maintenance scheduling and the selection of materials for new infrastructure. The framework further integrates scenario analysis, uncertainty quantification, and risk-based decision-making, thereby supporting the transition from reactive to predictive and adaptive asset management strategies.
A collection of technology highlights pulled from recent papers published in ECS journals.
Everyone involved in electrochemistry knows the Ernest B. Yeager Center for Electrochemical Sciences (YCES) at Case Western University. It has been a jewel of an academic center for almost 50 years (formally), but in reality, for much longer than that with Professor Frank Hovorka starting at Western Reserve University in 1925, barely two decades after ECS was founded.
Electrochemical processes, including electric double-layer charging and discharging, electrosorption of reaction intermediates and electrolytes, and charge-transfer reactions, occur at the electrode-electrolyte interface (EEI). Maximizing the rates of these electrochemical processes requires increasing the electrode’s surface area while maintaining efficient mass transport. Porous electrodes meet these competing requirements by introducing interconnected pore networks into the electrodes.
Electrochemical impedance spectroscopy (EIS) is an integral part of electrochemical studies, with application to diverse topics such as fuel cells, batteries, corrosion, sensors, and biomedical devices. Here, we provide three contributions from leaders in the use of impedance spectroscopy.
Summer is winding down as I write this, and I am looking forward to the fall and the upcoming ECS Meeting in Chicago. First, however, let’s look back at May’s outstanding 247th Meeting in Montréal, Canada, and review key activities that have since followed.
This feature is intended to let ECS award-winning students and post-docs write primary author perspectives on their field, their work, and where they believe things are going. This month we highlight the work of Eric M. Fell, recipient of the 2024 ECS Battery Division Student Research Award.
Engaging directly with lawmakers is essential if climate change, public health, emerging technology, and national security decisions are to be based on evidence rather than ideology or misinformation. Active engagement empowers informed, sound decisionmaking, secures sustainable research support, and strengthens the US's capacity to meet complex challenges with knowledge and innovation.
