Molecular insights into redox-enhanced capacitive energy storage

• Applicant: Professor Dr. Christian Holm
• Subject Area: Statistical Physics, Nonlinear Dynamics, Complex Systems, Soft and Fluid Matter, Biological Physics ; Theoretical Chemistry: Electronic Structure, Dynamics, Simulation
• Term: since 2026
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 576543047

The growing global energy demand and the urgent need for environmentally sustainable solutions are driving the search for innovative energy storage technologies. Electrical double-layer capacitors (EDLCs), commonly referred to as supercapacitors, are sustainable energy storage devices with diverse applications, including the harvesting of intermittent renewable energy sources such as wind power and the recovery of energy from regenerative braking systems. While EDLCs offer high power density and exceptional cycle life, their energy density remains modest compared to batteries. To address this limitation, significant efforts have been focused on increasing their storage capacity. One promising strategy involves coupling capacitive charge storage with fast redox processes—such as pseudocapacitance and redox-active electrolytes—offering the potential for substantially enhanced performance. However, there is a lack of understanding of the coupling between redox and capacitive processes, primarily driven by the absence of appropriate computational tools capable of accurately and efficiently modelling non-equilibrium redox phenomena at the molecular level. This project aims to fill this critical gap by developing a multiscale-compatible, coarse-grained molecular simulation framework for modelling redox phenomena. Two complementary methods will be implemented: (i) a potential-based approach that incorporates activation barriers and binding energies, and (ii) a stochastic method in which reaction events are governed by predefined probabilities between redox species or between a redox species and the electrode surface. These methods will be applied to investigate two types of systems: (1) redox reactions of electrolyte ions at functionalized electrode surfaces—such as proton redox at oxygen sites—and (2) redox-enhanced electrolytes that include freely diffusing redox-active species in addition to conventional electrolyte ions. Our central goal is to understand the interplay between redox activity and capacitive charge storage, particularly in relation to pseudocapacitive behaviour, and to identify strategies for increasing energy density. Examining the performance of redox-enhanced electrolytes, we will particularly focus on mitigating self-discharge, one of the key limitations of these systems. In both cases, simulations will be conducted for flat and slit-shaped microporous electrodes to explore how microporosity influences the physicochemical properties of redox-active EDLCs. Our simulations will yield new insights into the fundamental physics of redox-enhanced capacitive energy storage and help identify strategies to increase the energy density of supercapacitors. Beyond their direct relevance to modelling supercapacitors, batteries, and hybrid technologies, the simulation methodologies developed in this project will apply to a broader class of systems where chemical reactions play a central role, such as biologically relevant environments.

• DFG Programme: Research Grants
• International Connection: Poland
• Cooperation Partner: Dr. Svyatoslav Kondrat