cnrs I international w 22 | Focus magazine THE MYSTERY OF MAT ERIALS Yet the heart of the problem with supercapacitors is, once again, the material they are made of. The process used today to manufacture porous carbon results in pores that vary in size from less than 2 nanometers to more than 50. Challenging the conventional idea that medium-sized pores (2 to 5 nm) are best suited for trapping ions, the CIRIMAT researchers, with the help of an American researcher specializing in ceramics, set out to synthesize a porous carbon with perfectlycontrolled pore sizes below 2 nanometers. To their surprise, the new material delivered twice as much energy as could be expected from theoretical findings. The next step will be to determine the mechanisms involved, especially how the ions are able to penetrate such small pores. This research was conducted jointly with the laboratories of the RS2E’s Capacitive Storage group,6 while the modeling of the carbon pores was entrusted to the PECSA7 and the IFPEN.8 It is this type of multidisciplinary cooperation that makes the network so effective. “In highpotential fields like sodium-ion batteries and redox flow, the RS2E allows us to create a continuum between CNRS researchers, public industrial and commercial institutions, and industrial users, which jointly supervise PhD theses and postdoc research,” Tarascon emphasizes. “Through the RS2E, we are able to support the exploration of new materials that will be of interest to us in the long term,” concludes Anne de Guibert, senior researcher for the French battery manufacturer Saft. J.-F. H. 01. Laboratoire de réactivité et chimie des solides (CNRS / Université de Picardie J ules V erne). 02. Réseau sur le stockage électrochimique de l’énergie. 03. Institut des matériaux de Nantes (CNRS / Université de Nantes). 04. Institut des sciences analytiques et de physicochimie pour l’environnement et les matériaux (CNRS / Université de Pau et des Pays de l’Adour). 05. Centre inter-universitaire de recherche et d’ingénierie des matériaux (CNRS / Université Paul Sabatier-Toulouse-III / INP Toulouse). 06. IMN (Nantes), ICG-AIME (Montpellier), CIRIMA T (Toulouse), ICMCB (Bordeaux), IS2M (Mulhouse), LCMCP (Chimie Paris Tech). 07. Physicochimie des électrolytes, colloïdes et sciences analytiques (CNRS / UPMC / ESPCI ParisTech). 08. IFP Energies Nouvelles (the former French Petroleum Institute). 09 The production of a porous carbon powder film to be used as an electrode in the supercapacitors developed at the CIRIMAT . 10 Researchers are studying the structural organization of porous carbon-based materials. 09 10 © p hotos 9-10 : H . RAG UET/CNRS Photothèque Contact information: Jean-Marie Tarascon > jean-marie.tarascon@u-picardie.fr Danielle Gonbeau > danielle.gonbeau@univ-pau.fr Patrice Simon > simon@chimie.ups-tlse.fr sm all in si ze, big on perf orm ance This is the age of mobile electronics, a technology based on tiny communicating sensors that can store an array of parameters. RFID (radio frequency identification) chips, for example, are used to identify many types of objects. But how can these micro-devices be powered? Ideally, by recovering energy from the environment—in the form of sunlight, mechanical vibrations, or temperature differentials that can generate electricity. But this energy is intermittent, which means it must be stored. To this end, a team at the LAAS1 in Toulouse has developed a “micro-supercapacitor” consisting of gold structures placed on a silicon chip and covered with an active material and an electrolyte (conductive solution). Activated carbon, the most commonly used material in commercially-available supercapacitors, is replaced by carbon nanoparticles. Made up of concentric layers of graphite produced at Drexel University in Philadelphia (US), these particles greatly improve the adsorption of the ions in the electrolyte. Tested at the CIRIMAT,2 also in Toulouse, the device proved to have a charge/discharge rate 50 times faster than a conventional supercapacitor, as well as 10 times its energy density. This performance makes it well-suited for powering sensors that need to supply rapid, steady streams of data. 01. Laboratoire d’analyse et d’architecture des systèmes (CNRS / Université Paul Sabatier-Toulouse-III / Insa Toulouse / INP Toulouse). 02. Centre inter-universitaire de recherche et d’ingénierie des matériaux (CNRS / Université Paul Sabatier-Toulouse-III / INP Toulouse). Contact i nformation: Magali Brunet, mbrunet@laas.fr 08 Encapsulated microsupercapacitors are very promising devices. 08 © H . Dur ou/LAA S-CNRS
CIM30
To see the actual publication please follow the link above