Electrochemical energy storage

Micro-supercapacitors

Principal investigators: Alessandra Sanson, Nicola Sangiorgi

Involved personnel: Alex Sangiorgi

Currently, the large amount of energy produced from renewable sources requires highly efficient and stable storage systems to be used when needed. This requirement is valid for both stationary and portable applications. CNR-ISTEC carries out research activity focused on the study and production of micro-supercapacitors for portable applications with gel electrolyte on different types of substrates (rigid or flexible).

In particular, the research activity involved the application of transparent conductive substrates based on glass and FTO or PET respectively or on graphite or metal ones. The devices developed are designed for portable electronics where the transparency, flexibility and absence of liquid components are fundamental requirements.
The electrodes materials developed are based on metal oxides such as TiO₂, ZnO and NiO that possess high pseudo-capacitive capacitance. At the same time, organic materials like graphene oxide or conducting polymers (and hybrids with metallic nanoparticles) films are used as double-layer capacitive electrodes. The optical properties, morphologies and electrochemical properties (charges storage) are optimized during the synthetic process in order to obtain highly efficient supercapacitor electrodes. Finally, for specifically portable application and to increase the device stability, the liquid electrolyte is replaced with a gel one. To do that, different gelling agents based on silica nanoparticles, nanoclay or polymers are used. Each single element developed and the final micro-supercapacitors are tested considering their optical, morphological, microstructural and electrochemical (specific capacitance) properties. Moreover, particular attention is devoted to determine the stability of these devices. Finally, the electrochemical properties of the different interfaces created (i.e. solid-liquid or solid-solid) are determined by Electrochemical Impedance Spectroscopy technique.

Equipment and processes

A low temperature process based on electrochemical deposition methods are optimized and used for the preparation of electrode materials based on ZnO, graphene oxide and conducting polymers, in order to avoid possible thermal damages of the flexible polymeric substrate based on PET. On the other hand, when metallic or glass-based substrates and TiO₂ are considered, a screen-printing process is considered followed by a thermal treatment of consolidation. Novel additive manufacturing techniques based on inkjet or microextrusion are considered to develop complex patterns with a flexible technique.
All the electrochemical characterizations (specific capacitance, electrochemical properties, electrochemical impedance and stability) on single electrodes or final devices are performed by Autolab PGSTAT 302N + FRA32 M. The optical properties are determined using the integrating sphere of PVE300 system (both in transmission or reflection mode).

Main partners

• Università di Bologna
• Instituto de Cerámica y Vidrio (CSIC-ICV) 

Publications

• B. Ballarin, E. Boanini, L. Montalto, P. Mengucci, D. Nanni, C. Parise, I. Ragazzini, D. Rinaldi, N. Sangiorgi, A. Sanson, M.C. Cassani, “PANI/Au/Fe₃O₄ nanocomposite materials for high performance energy storage”, Electrochimica Acta 2019, 322, 134707-134715.
• J. Yus, Z. Gonzalez, A.J. Sanchez-Herencia, A. Sangiorgi, N. Sangiorgi, D. Gardini, A. Sanson, C. Galassi, A. Caballero, J. Morales, B. Ferrari, “Semiconductor water-based inks: miniaturized NiO pseudocapacitor electrodes by inkjet printing”, Journal of the European Ceramic Society 2019, 39, 2908-2914.
• Y. Vlamidis, E. Scavetta, M. Giorgetti, N. Sangiorgi, D. Tonelli, “Electrochemically synthesized cobalt redox active layered double hydroxides for supercapacitors development”, Applied Clay Science, 2017, 143, 151-158.