Research network on electrochemical energy storage,
Research center on batteries and supercapacitors

Micro-energy storage: supercapacitors and microchips

Micro-energy storage: supercapacitors and microchips
© C. Lethien/IEMN


A French research group from RS2E led by Patrice Simon (CIRIMAT, CNRS /Université Toulouse III - Paul Sabatier / INP Toulouse), the winner of the 2015 CNRS Silver Medal, proposes a way to store energy directly onto silicon microchips. As an added bonus, their manufacturing process is highly compatible with those of the industry. The results were published in the journal Science on February 12, 2016. The performances are the best known to date.

 

Maxi-competition for micro-supercapacitor
The appeal to include energy storage micro-devices directly onto microchips is high. As a result the competition has been fierce during the last five years between researchers. Many production methods were studied, some through wet processing routes. However these methods are not completely compatible with the processes used in semiconductor factories which seriously hinders their wide use. Other ways have other constraints (the highly publicized laser etching method of Kaner’s Group has good power performance but its energy performance are lacking). A team of French researchers associated with a Russian-American scientist proposes the best solution to date : a miniature energy storage device called a micro-supercapacitor.

The laboratories involved in this adventure bring together the Centre interuniversitaire de recherche et d'ingénierie des matériaux (CIRIMAT, CNRS/Université Toulouse III - Paul Sabatier/INP Toulouse) and the Laboratoire de physique et chimie de nano-objets (LPCNO, CNRS/INSA Toulouse/Université Toulouse III - Paul Sabatier 3), the Institut d'électronique, de microélectronique et de nanotechnologie (IEMN, CNRS/Université de Lille/Université de Valenciennes and Hainaut-Cambrésis/ISEN Lille/Ecole Centrale de Lille) and the laboratoire réactivité et chimie des solides (LRCS, CNRS/Université de Picardie Jules Verne) in Amiens. The study took within the French network on electrochemical energy storage (RS2E) of CNRS.


The published performances are the best known to date
The concept is both compatible with current production processes and provides very good adhesion to the silicon substrate (chip) thanks to an original structure. The latter is composed of a "support" layer of titanium carbide (TiC) inbetween the carbide (supercapacitor) and the silicon chip.The group also observed a very good structural uniformity of its supercapacitors. In the end, they get the best surface energy/surface power ratio of the moment.

Even better, if the synthesis reaction is taken to completion, the entire TiC "support"  layer is transformed into a supercapacitor, which can be then separated from the silicon substrate. This self-supporting film is mechanically stable and micrometic. Thereby it is potentially usable for flexible or wearable applications. Beyond the energy storage application, these materials offer prospects for the development of elastic coatings having a low friction’s coefficient or for the production of membranes for gas filtration.

 

References
On-chip and free-standing elastic carbon films for micro-supercapacitors
P. Huang, C. Lethien, S. Pinaud, K. Brousse, R. Laloo, V. Turq, M. Respaud, A. Demortière, B. Daffos, P.L. Taberna, B. Chaudret, Y. Gogotsi, P. Simon
Science, 12/02/2016, DOI : 10.1126/science.aad3345
http://dx.doi.org/10.1126/science.aad3345