Research
Dynamic Multifrequency Analysis
Electrochemical Impedance Spectroscopy (EIS) is a common technique used in the field for the estimation fo kinetical parameters for the processes at an interface. The impedance is defined for linear and stationary systems. When the condition of stationarity cannot be practically met, or otherwise when the system is artificially drifting, the instantaneous impedance can still be evaluated considering the linearisation of the dynamic system around different operating points. For the practical realisation of such concept, the group has developed a methodology called Dynamic Multi-Frequency Analysis based on pass-band filtering of multi-frequency voltage and current data.
Electron-Ion transfer at the Interface
At the heart of all electrochemical processes lies the electrode-electrolyte interface, where complex physical and chemical phenomena unfold across wide spatial and temporal scales. Electron transfer from the electrode is typically modelled by the Butler-Volmer equation or Marcus theory, both influenced by the thermodynamic properties of the involved species - such as concentration, redox potential, and overpotential. Meanwhile, ion transport occurs via migration in electric fields and diffusion, and may involve adsorption at surfaces or insertion into solid lattices. These processes couple in the electric double layer, a region of broken electro-neutrality where additional effects - such as the Frumkin correction - further complicate the dynamics. At ESECS, these interfacial phenomena are investigated using advanced electrochemical techniques like dynamic multifrequency analysis, innovatively combined with the quartz crystal microbalance.
Modelling of electrochemical systems
This research investigates multi-physical modelling of energy storage systems. Objectives include developing robust, high-fidelty models for batteries operating under extreme conditions, capturing phenomena at the electrode-electrolyte interface, optimising material properties, and predicting degradation mechanisms. Key applications involve various battery types and supercapacitors. Morover, dynamic electrochemical impedance spectroscopy (DEIS) is modelled to improve the understanding and performance of these systems, and is used to characterise specific electrochemical provesses (e.g. redox reactions and hydrogen evolution).
Aging of Lithium-Ion Batteries
For the diffusion of batteries through different technological sector, it is crucial to understand the mechanism and causes of the degradation of the cells. Physical-based models are accurate but computationally expensive to solve and their reduction to simpler symmetries might lose the ability to represent aging. The alternative approach of data-driven modelling treats the cell as a "black box" in which the input-output relation is modelled with statistical methods. Our group is focused on using broad-band non-stationary impedance data (100kHz-10mHz) as source to parametrise such statistical models as well as mutli-scale models ("grax-box" model) developed in-house.
Rechargeable aqueous metal-ion batteries
We advance sustainable energy storage by developing rechargeable aqueous metal-ion batteries, focusing on zinc-ion systems. These batteries are safe, low-cost and eco-friendly, making them ideal for large-scale applications like grid storage. Zinc is abundant and stable in water-based electrolystes, enabling non-flammable batteries that operate under ambient conditions. Our research investigates zinc-ion storage mechanisms and designs new electrode materials and electrolytes to boost efficiency, lifespan, and energy density. Combining materials science, electrochemistry, and systems engineering, we aim to build high-performance batteries for a resilient, low-carbon future.
Lithium extraction and recycling
Electrochemical ion-pumping (EIP) is a process for extracting lithium ions from natural brines, like geothermal waters. It could tackle the increasing global demand for lithium and the ecological problems associated with the current extraction methods. In the EIP process, the high-volumetric feed solution and a low-volumetric recovery solution alternately flow through the reactor, while alternately a negative and positive electric current is applied. The lithium-selective working electrode captures the Li+ ions from the feed solution and releases them into the recovery solution. For fulfilling the charge balance, a lithium exclusive counter electrode intercalates and de-intercalates cations. The resulting increase of the Li+ concentration, enables precipitation.