Several new and emergent chemistries for electrochemical energy storage are based on the understanding and the engineering of the electrode/electrolyte interface. The approach followed in this line to bring these concepts closer to practical reality involves the preparation of nanostructured materials to use in batteries, and the study of the electrode processes by electrochemical and physical techniques.
The great success of the lithium-ion battery is based on the intercalation reaction, which involves the bulk of the active electrode material and is compatible with a static interface, allowing a large cycle life. Novel concepts and chemistries pursue improving the established Li-ion technology, in one or more properties of such as energy density, cost, sustainability. Use of metallic anodes, air or sulfur cathodes, or flow batteries imply the deposition and dissolution of the active material, and therefore an evolving interface and/or redox catalytic processes at the interface. Controlling composition and nanostructure of the interface is the main focus in this line.
Current research activities are grouped into the following topics:
Templated and porous electrode materials
Binder-free inverse opal carbons with pores of different sizes to study the effects of architecture on the electrochemistry of Li-air cathodes
The challenges of novel electrochemical energy storage systems are often related to more difficult reactions, i.e. slower or less reversible electrochemical processes. The development of appropriate material architectures that multiply the number of reactions sites by expanding the interface area and providing appropriate ionic channels and electron wiring without compromising density or cost is critical for efficient devices. However, the use of well-defined controlled structures is also a strategy for the understanding of fundamental phenomena and the experimental localization of possible system bottlenecks, which serves as guide for the further design of improved materials.
Based on these concepts, we have been developing materials mainly for metal-air batteries. Aprotic Li/O2 batteries are based on the precipitation of insulating Li2O2 in the porous conducting matrix of the cathode during discharge. Li2O2 formation and removal need to be properly managed to ensure effective operation. To understand what parameters of the porous network optimize discharge capacity, rate capability and reversibility, two approaches have been followed: 1) using model systems with well-defined pore structure and 2) modeling pore filling of practical carbons based on their experimental pore size distribution (PSD). To determine the degree of utilization of the cathode porosity we fabricate ideal structures where we exactly know pore sizes and their arrangements, such as inverse opals.
Another path for the production of attracting materials for energy storage is based on the control of nanostructuration through low cost and sustainable raw materials and routes. Our studies center on processes of drying and carbonization in specific environments to obtain appropriate porous structures from widely available renewable precursors such as bacterial nanocellulose.
- Olivares-Marín, M. Aklalouch, Dino Tonti “Combined influence of meso- and macroporosity of soft-hard templated carbon electrodes on the performance of Li-O2 cells with different configurations” Nanomaterials 9, (2019) 810
- Pérez del Pino, A. Martínez Villarroya, A. Chuquitarqui, C. Logofatu, D. Tonti and E. György “Reactive laser synthesis of nitrogen-doped hybrid graphene-based electrodes for energy storage” Journal of Materials Chemistry A 6 (2018) 16074
- Aklalouch, M. Olivares-Marín, R.C. Lee, P. Palomino, E. Enciso and D. Tonti, “Mass-transport Control on the Discharge Mechanism in Li–O2 Batteries Using Carbon Cathodes with Varied Porosity” ChemSusChem 8 (2015) 3465-3471
- Olivares-Marín, P. Palomino, E. Enciso and D. Tonti, “Simple Method to Relate Experimental Pore Size Distribution and Discharge Capacity in Cathodes for Li/O2 Batteries” Journal of Physical Chemistry C 118 (2014) 20772-20783
- Olivares-Marín, P. Palomino, J.M. Amarilla, E. Enciso and D. Tonti, “Effects of architecture on the electrochemistry of binder-free inverse opal carbons as Li-air cathodes in an ionic liquid-based electrolyte” Journal of Materials Chemistry A, 1 (2013), 14270
Metal-air and flow batteries
Enhancement of the discharge capacity of a Li-O2 battery by adding a novel radical molecule in the electrolyte.
The nanostructured, mostly carbonaceous materials described above are developed mainly for application in metal-air and redox flow batteries. These systems target high energy density and large scale storage respectively, and can encompass a wide array of specific chemistries. However they have in common that generally the required redox processes take place by electron transfer at the electrode surface and may involve a product deposition. The related problems of electrocatalysis and of the deposition distributions may be influenced by supply of active species, solvation and soluble catalysts. Therefore the influence of all components in the full system is investigated, which includes electrolyte formulations, redox mediators and other additives, as well as design and study of novel cell concepts. The main focus is currently on the reversibility of Li- and Zn-air batteries, as well as the kinetics in V redox flow batteries.
- Badetti, V. Lloveras, E. Amadio, R. Di Lorenzo, M. Olivares-Marin, A.Y. Tesio, S. Zhang, F. Pan, K. Rissanen, J. Veciana, D. Tonti, J. Vidal-Gancedo, C. Zonta, and G. Licini “Organic PolyRadicals as Redox Mediators: Effect of Intramolecular Radical Interactions in their Efficiency” ACS Applied Materials & Interfaces DOI: 10.1021/acsami.0c09386
- Homewood, J.T. Frith, J.P. Vivek, N. Casan-Pastor, D. Tonti, J.R. Owen and N. Garcia-Araez “Using polyoxometalates to enhance the capacity of lithium-oxygen batteries” Chemical Communications 54 (2018) 9599
- Cecchetto, A. Y. Tesio, M. Olivares-Marín, M. Guardiola Espinasa, F. Croce and D. Tonti “Tailoring oxygen redox reactions in ionic liquid based Li/O2 batteries by mean of the Li+ dopant concentration” Sustainable Energy & Fuels, 2 (2018) 118-124
- Landa-Medrano, M. Olivares-Marín, B. Bergner, R. Pinedo, A. Sorrentino, E. Pereiro, I. Ruiz de Larramendi, J. Janek, T. Rojo and D. Tonti “Potassium Salts as Electrolyte Additives in Lithium–Oxygen Batteries” Journal of Physical Chemistry C 121 (2017) 3822–3829
- Y. Tesio, D. Blasi, M. Olivares-Marín, I. Ratera, D. Tonti and J. Veciana “Organic radicals for the enhancement of oxygen reduction reaction in Li–O2 batteries” Chemical Communications, 51 (2015) 17623-17626
- Landa-Medrano, M. Olivares-Marín, R. Pinedo, I. Ruiz de Larramendi, T. Rojo and D. Tonti, “Operando UV-visible spectroscopy evidence of the reactions of iodide as redox mediator in Li-O2 batteries” Electrochemistry Communications 59 (2015) 24-27
X-ray characterization of battery materials
When a product precipitates during the electrochemical process, the precise knowledge of composition and morphology of the nano-sized deposits provides valuable information on their formation process that need to be understood in detail to obtain true reversible operation. Within this activity, we introduced the use of energy-dependent full field transmission soft x-ray microscopy (TXM) using synchrotron radiation to study the reactions in the oxygen electrode of Li-air batteries. The TXM high energy and space resolution provide semiquantitative chemical information at the scale of few tens of nm. The unique access to the oxygen chemical state allowed detecting the critical superoxide component and its interplay with the other compounds present in the precipitate. The use of this technique has been extended to the mapping of the intercalation state in other battery active materials and complemented with hard x-ray absorption, allowing to observe core-shell effects or insurgence of local heterogeneities among particles, providing relevant insights on the charge redistribution and the irreversible processes to guide the development of more reliable battery systems..
- Simonelli, A. Sorrentino, C. Marini, N. Ramanan, D. Heinis, W. Olszewski, A. Mullaliu, A. Birrozzi, N. Laszczynski, M. Giorgetti, S. Passerini, D. Tonti “Role of Manganese in Lithium- and Manganese-Rich Layered Oxides Cathodes” Journal of Physical Chemistry Letters 10 (2019) 3359-3368
- Olivares-Marín, A. Sorrentino, E. Pereiro, and D. Tonti “Discharge products of ionic liquid-based Li-O2 batteries observed by energy dependent soft x-ray transmission microscopy” Journal of Power Sources 359 (2017) 234–241
- Landa-Medrano, A. Sorrentino, L. Stievano, I. Ruiz de Larramendi, E. Pereiro, L. Lezama, T. Rojo and D. Tonti “Architecture of Na-O2 Battery Deposits Revealed by Transmission X-ray Microscopy” Nano Energy 37 (2017) 224–231
- Tonti, M. Olivares-Marín, A. Sorrentino, and E. Pereiro, “Studies of Lithium-Oxygen Battery Electrodes by Energy- Dependent Full-Field Transmission Soft X-Ray Microscopy”, in “X-ray Characterization of Nanostructured Energy Materials by Synchrotron Radiation”, edited by M. Khodaei and L. Petaccia (InTech, 2017).
- Olivares-Marín, A. Sorrentino, R.C. Lee, E. Pereiro, N.L. Wu and D. Tonti, “Spatial Distributions of Discharged Products of Lithium–Oxygen Batteries Revealed by Synchrotron X-ray Transmission Microscopy” Nano Letters 15 (2015) 6932-6938