Materials for electrochemical energy conversion: synthesis, ex-situ and operando characterization

Autosampler of a NMR

The research activity chiefly deals with the fabrication of innovative materials for electrochemical ener gy conversion (e.g. polymer fuel cells), and with their structure, thermal and functional characterization.

A relevant part of the research is also devoted to the development on NMR/MRI methods for operando investigation of interfaces and devices for electrochemical conversion and storage.

Membranes and membrane-to-electrode assemblies (meas) for polymer fuel cells

Polymer fuel cells operating al low temperature (< 100°C) are the systems-of-choice for energy conversion for automotive (buses, trucks, shuttles) and for grid applications. At present, the state of the art is represented by proton-conducting devices operating with NafionTM membranes. These fuel cells suffer of several problems, e.g. need of precious metal catalysts (e.g. platinum and platinum-group metals (PGM)), catalyst poisoning by CO at low temperature, membrane high cost. Alternative routes are offered by proton-conducting devices operating in the range 100-200°C, which based on membranes made by polybenzimidazole and related composite materials. This allows to reduce the membrane cost. Another intriguing possibility is to move towards anion (OH) conducting membranes, which allow substituting the PGM catalysts with other based on cheap elements (e.g. Fe). The research line aims at developing and characterizing both proton- and OH-conducting materials.

Solid polymer and composite electrolytes for energy storage

At present, the market of nmr/mri operando characterization is dominated by lithium-ion rechargeable batteries. These batteries, however, have not enough energy density to support the demanding requirements of automotive, and are not really safe because of the high volatility and flammability of the organic liquid electrolyte. The quest for higher energy density can be solved by substituting the graphite anode with a lithium metal one, originating the so-called lithium metal batteries (LMB). These batteries require a solid electrolyte able to block the formation of lithium dendrites which can cause short circuits and battery faults. The availability of solid electrolytes will also help to solve the present safety problems. This research line aims at developing solid electrolytes based on functional polymers, e.g. poly(ethylene oxide) (PEO), or on polymer-ceramic nanoarchitectures.

NMR/MRI operando characterization

The functional characterization of materials involved in electrochemical interfaces, or even in full devices, cannot prescind from their study under conditions as near as possible to real operation (operando conditions). This indeed requires the use of non-destructive characterization techniques, e.g. X-rays, electron microscopies, of spectroscopies like RAMAN or NMR. This research line aims at developing and applying advanced methodologies of NMR spectroscopy and micro-imaging (MRI) to the operando investigation of materials for batteries, supercapacitors and fuel cells.

 

Research Group

Facilities
  • Solid-state 400 MHz NMR spectrometer with microimaging accessory
  • Test station for fuel cells
  • High-pressure/high-temperature autoclave for polymer synthesis
  • Test systems for batteries, frequency response analyzers, potentiostats/galvanostats (in cooperation with Riccardo Ruffo)
Functional microimages under operando conditions of a polybenzimidazole membrane during working in fuel cell