Research

Our research focuses on the development of novel advanced functional materials for supercapacitors, lithium, and post-lithium-ion batteries, with a special focus on tackling challenges of novel battery concepts such as Na, K, Zn, Al batteries and sulfur-based systems. Our work is not only limited to the “electrode” materials but also includes the study of other active and inactive components such as binder, separator, conductive carbon, current collector and electrolytes and their mutual interactions in electrochemical cells.

Na-ion batteries

Among the “post-lithium” systems, the Na-ion battery is the most advanced one and has been recently developed at an industrial scale by several companies and startups around the globe. Despite the substantial similarity of Na with Li, the shift from one technology to the other is not straightforward as the reactivity of the two alkali metals is different: Moving from Li to Na (and K) requires a complete reassessment of materials and components (what is working with lithium may not work with sodium and vice-versa).

Na-ion batteries

From a fundamental point of view, we work on developing novel high-capacity and sustainable cathode materials, such as layered oxides or other types of materials (e.g., phosphates) and the formulation of novel electrolytes. We are also studying pre-sodiation with sacrificial additives to tackle the irreversible capacity loss and the sodium deficiencies of Na-based cathode materials.

Aluminum-based batteries

Among possible “beyond lithium” candidates, Aluminum is the most abundant one, and, due to its tri-valence, can theoretically provide three times more charge per redox center as compared to Lithium. However, multivalent systems are much more complicated than monovalent ones due to their higher charge density and to the poorer solubility of their salts. A critical drawback of Aluminum batteries is the requirement of the AlCl₃ salt in the electrolyte to enable efficient plating and stripping. However, AlCl₃ is very corrosive and restricts the use of available current collectors to Molibdenum, Tungstenum, or metal nitrides such as TiN or Cr₂N. In addition to this, the electrolyte is highly reactive toward the binder; it dissolves many cathode materials and even destroys the aluminum foil itself upon repeated cycling.

In our group, we aim to push the boundaries of research on Aluminum batteries by addressing several of these issues and tackling them from different fronts: on one side, we work on the formulations of non-corrosive electrolytes, which would have the advantage of overcoming the corrosion problem, but the drawback of having poor performance as compared to standard electrolytes. On the other side, we are working on the optimization and stabilization of the different components of the electrode and of the cell in a way that they can be “compatible” with the corrosive AlCl₃/Ionic Liquid electrolyte.

Metal-sulfur batteries

Sulfur is highly abundant and cost-effective and can theoretically deliver very high capacity compared to conventional Li-ion battery cathodes. Starting with a combination of sulfur-based cathodes with Li-metal anodes, in our group, we aim to develop even more sustainable batteries based on sodium-sulfur and aluminum sulfur.

Na (and Al) sulfur batteries are sustainable, cost-effective, and high-energy-density energy storage systems. Still, several crucial roadblocks impede the exploitation of this technology: the reaction at the S cathode usually involves solid-liquid transitions, which induces polysulfide shuttling from the cathode to the anode, the formation of dendrites on metallic Na (or Al), their passivation and cell failure. Enabling a solid-solid transition would mitigate the shuttling but hinder the reaction kinetics. Such roadblocks need to be tackled from different directions: The polysulfide solubility should be mitigated by engineering polymer-based cathodes (work we are doing in collaboration with Prof. Hatice Mutlu in Mulhouse) and fine-tuning the electrolyte. In parallel, we investigate strategies to prevent shuttling, such as using functional separators/protective layers and electrocatalysts.

From electric double-layer capacitors to pseudocapacitors and hybrid configurations

To meet growing demands for electric automotive and regenerative energy storage applications, researchers worldwide have sought to increase the power density of batteries and the energy density of electrochemical capacitors. Hybridizing battery capacitor electrodes can overcome the energy density limitation of conventional electrochemical capacitors because they employ both the system of a battery-like (redox) and a capacitor-like (double-layer) electrode, producing a larger working voltage and capacitance. Our goal is to hybridize materials at a molecular level by incorporating the battery-like material with a carbonaceous capacitor-type material and to adopt different strategies for incorporating faradaic materials:

Cap1

Cap2