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Anthropogenic climate change entices civilisation to adopt renewable energy that requires electric storage due to its intermittent nature. Batteries are traditionally responsible for storing electricity because of their large density of energy but they are expensive because they degrade significantly faster than supercapacitors. However, supercapacitors store a lower density of energy. Like renewable energy, these devices must minimise their ecological footprint and enforce the concept of circular economy but the current production of both batteries and supercapacitors has much room for improvement. Increasing the area of supercapacitors' electrodes is key to producing more energy. These are made of nanofibres of carbon because they are conductive and hold a large surface. They are made from polymers traditionally produced from fossil fuels. However, recent research successfully replaced these expensive ingredients with a polymer wasted by the industry of pulp and paper. Instead of burning the waste to supply the industry with energy, and releasing greenhouse gases to the atmosphere, it is possible to simply convert the polymer to carbonic nanofibres at scales thanks to electrospinning and thermal treatment. However, their performance remains inferior to those reported in literature. Chemically doping the carbonic nanofibres is a popular option with extensive presence in literature but increasing the surface is a simple mean to also increase the capacity of storing energy. Electrodes made from nanofibres are so porous that much of their volume is void. Compressing the nanofibres to roughly half their volume prior to thermally treating the carbonic nanofibres translated in an increase of 2.21 fold in density after the thermal treatment. The surface of the samples per unit volume increased by 2.34 times yet the volumetric capacitance decreased by 78% even though the resistivity decreased by 56%. First material characterisation on the samples identifies the presence of carbonic nanofibres through measurements of conductivity, Raman spectroscopy, X-ray diffraction and Scanning Electron Microscopy. Then, electrochemical characterisation evaluates the performance of the samples in a device, including Cyclic Voltammetry for 10,000 charging and discharging cycles, Galvanostatic Charge and Discharge, and Electrical Impedance Spectroscopy to evaluate their performance in a supercapacitor.

The electrospinnability of lignin with the help of Polytheylene oxide, to produce electrospun carbon nanofibers, used for electrodes of various energy storage devices, is seducing the scientific community for its abundance, renewability, cost and the simplest, industrially scalable process. As for each and every technical lignin available in nature, the native lignin used here is the least energy consuming. A detailed, reproducible method is recorded, and a personalized heat treatment following electrospinning is produced to present the best conductivity of the electrospun carbon nanofiber. Further analysis and applications of the electrodes produced from these nanofibers are investigated. A promising upgrade seeks to filling the many pores in the fibers produced to increase the capacity of the electrodes crafted from these carbon nanofibers.

International audience; The ribbon on sacrificial template (RST) process is a ribbon direct-wafering technology with specific ability for high throughput and thin multicrystalline wafer production, in the range of 60-140 μm. Mechanical and electrical properties of the RST material were investigated. Ball on ring and four-point bending tests showed good fracture stress values up to 260 MPa. The conversion efficiency potential for passivated emitter and rear cells (PERC) made out from the RST material, around 16%, is shown to be limited by defects reducing minority carrier lifetime. The interaction between impurities, such as C and transitions metals, with structural defects such as dislocations, results in highly recombinative areas in RST wafers. A model is proposed which shows that the carbon substrate is an important source of carbon contamination in the silicon melt during the growth of the ribbon. This high C contamination can be accompanied by transition metal contamination and can have an influence on the growth stability and on the generation of structural defects, especially if C accumulates in a boundary layer just above the growth interface. The study of the segregation of Sb indicates that the process conditions are close to the case of the diffusive regime near the solid/liquid interface, with a boundary layer thickness of about 70 μm.

Unknown outside the Asian jungles almost fourty years ago, the tiger mosquito Aedes albopictus, vector of several human pathogens, is now established across the 5 continents, including in urban areas. In France, a national plan for surveillance of dengue and chikungunya is active, and some autochthonous cases of transmission have been reported recently, underlying the present risk of transmission in areas where the mosquito is present. Probably first introduced in the Rhône-Alpes area via road transport, Ae. albopictus is since 2013 considered present and active in 5 on 8 departments. For the surveillance purposes, it is now a question of identifying areas suitable for this mosquito and how these areas could be colonized. Thus, the aim of this study is to build maps of susceptibility of Ae. albopictus presence in the Rhône-Alpes area by a modelling approach combining knowledge on both the climatic and environmental determinants for establishment., Inconnu en dehors des jungles asiatiques il y a encore quarante ans, le moustique tigre Aedes albopictus, vecteur de nombreux agents pathogènes humains, s’est désormais établi sur les cinq continents, y compris en ville. En France, il fait l’objet d’un plan national de surveillance de la dengue et du chikungunya et plusieurs cas de transmission autochtones ont été reportés récemment, soulignant ainsi la réalité du risque de transmission dans les zones où ce moustique est implanté. Probablement introduit en région Rhône-Alpes via le transport routier, Ae. albopictus est considéré comme présent et actif dans cinq des huit départements depuis 2013. Il est aujourd’hui question d’identifier les zones favorables à son implantation et comment la colonisation vers ces zones pourrait se faire. Ainsi, l’objectif de notre travail est de construire des cartes de susceptibilité de présence d’Ae. albopictus en Rhône-Alpes par modélisation combinant à la fois les connaissances sur les déterminants climatiques mais aussi environnementaux de son installation.

International audience