Daniel Baril

Electrochemistry of liquids vs. solids: Polymer electrolytes

The electrochemistry of polymers is reviewed, in comparison with solid or liquid electrolytes. It is shown that the coordination chemistry leading to the formation of conductive complexes is very general with specific interactions (e.g. transition metal-nitrogen). While the transference numbers are still the subject of controversies, a coordination chemistry akin to that of water for PEO or ammonia with PEI exists. Also, the possibility of redox conduction, through microphase separation leads to mixed conductivity (ions + electrons).

COMPARATIVE ELECTROCHEMICAL STUDY OF NEW POLY(OXYETHYLENE)-LI SALT COMPLEXES

The high ionic conductivity of alkali-metal salts complexed with poly(oxyethylene)(POE) has stimulated wide research on solid polymer electrolytes. Differential scanning calorimetry (DSC), cyclic voltammetry and conductivity measurements have been used to explore the fundamental electrochemical characteristics of two new promising Li salts: Li[(CF3SO2)2N](LiTFSI) and Li[(CF3SO2)3C](LiTriTFSM). A study of the ionic conductivity of membranes containing various concentrations of lithium salts as a function of temperature reveals that, when compared with all the other salts used so far, these new compounds markedly improve the conductivities, essentially as a consequence of lower crystallinity. The voltammograms between –0.2 and 3.9 V vs. Li+/Li° show that the three anhydrous complexes POE–LiTFSI, POE–LiTriTFSM and POE–50%LiTFSI–50%LiTriTFSM have a wide electrochemical stability window.

Inducing order in polymer

Abstract Polymer electrolytes have received much attention since the concept of all solid-state batteries had been introduced. Electrolyte structure depends on the nature of the salt and its concentration, which both have considerable impact on the state of the electrolyte. Their effects on properties like conductivity, glass transition temperature ( T g ), provide useful information on diffusive phenomena in such materials. Up to now, the strategy has been oriented to reach the maximum amorphicity of the polymer and the lowest T g . In contrast, we report here studies of salt–polymer complexes in which the solute is designed to induce some local order in the electrolytes (alignment, point or mirror symmetry). The influence of solute concentration and of the counter-cation is reported. Physico-chemical characterisation has been obtained by using conductivity, differential scanning calorimetry, and optical activity.

Proton-vacancy-conducting polymers based on anion-grafted ormosils synthesized via sol-gel process

A novel basic proton conducting polymer (so-called proton-vacancy conducting polymer) has been synthesized. It is based on the copolymerization via the sol-gel process of sulfonamide- containing groups, partially deprotonated, and an internal plasticizer (POE segments). All the organic groups are attached to trialkoxysilanes which, through the hydrolysis-condensation process, lead to a silica-based backbone. The flexible films obtained are homogeneous and transparent. Maximum conductivities are observed with approximately equals 15% of the sulfonamide groups deprotonated by the organic base and approximately equals 10% of 2000 Mw POE plasticizer. The conductivity values are 2 10-7Ω-1-cm-1 at 30 degree(s)C and 10-5 Ω -1cm-1 at about 84 degree(s)C. The polymers are thermically stable up to 220 degree(s)C and their electrochemical stability range is close to 2 V.

Le modèle chamanique soutient-il l’hypothèse adaptative de l’origine de la religion ?

Two diverging evolutionary accounts of religion are centered on explaining the phenomenon as an adaptive advantage versus an emergent phenomenon. In the first account, religion is seen as promoting health, with the link formalized in ancestral shamanism, for example. However, empirical research has not been conclusive in demonstrating a direct adaptive function of religion in this particular respect. The second account views religion as a derived product of non-religious adaptive abilities. This account is more compatible with the composite functions of the entity which is termed “religion.”

Le Père Noël, Piaget, Dieu et Darwin

Le but de cet article est de comprendre pourquoi, alors que les enfants attribuent les mêmes pouvoirs au Père Noël et à Dieu, la perte de croyance au premier n’entraîne pas la perte de croyance au second. Pour ce faire, nous effectuerons quatre analyses. La première concerne la relation entre la croyance au Père Noël et le développement cognitif. Dans la seconde partie, nous montrons que les enfants attribuent effectivement les mêmes pouvoirs au Père Noël et à Dieu. La troisième partie met en évidence que les dogmes religieux sont peu compatibles avec le développement cognitif des enfants. Enfin, trois arguments de nature évolutionniste devraient permettre d’éclairer le phénomène de la persistance des croyances religieuses. The aim of this article is to understand why, in spite of children attributing the same powers to Santa Claus and God, a loss of belief in the former does not lead to a loss of belief in the latter. To this end, we will perform four analyses. The first examines the relationship between a belief in Santa Claus and cognitive development. In the second part, we will show that children indeed attribute the same powers to Santa Claus and God. The third part demonstrates that religious dogmas are not very compatible with children’s cognitive development. Finally, three evolutionary arguments will shed light on the phenomenon of the persistence of religious beliefs.