Neutral candidates in approval and disapproval vote

In this article, the question is to select the “best” candidates within a set of candidates when voters cast approval-disapproval ternary ballots. That is, three options are offered to voters: casting a vote “in favor”, a “neutral” vote or a vote “against” each candidate. We first review desirable properties that a rule aggregating approval-disapproval ternary ballots should satisfy. We check whether the rules that have been proposed in the literature satisfy them. Then, we provide comparable axiomatizations of three rules: one is the lexicographical extension of the Approval rule for binary ballots; the second is the lexicographical extension of the Disapproval rule for binary ballots; and the third rule eliminates candidates with more opponents and fewer supporters than other candidates.The support of the Spanish Ministerio de Economía y Competitividad under project ECO2015-67519-P, and of the Departamento de Educación, Política Lingüística y Cultura from the Basque Government (Research Group IT568-13) is gratefully acknowledged

Neutral candidates in approval and disapproval vote

In this article, the question is to select the “best” candidates within a set of candidates when voters cast approval-disapproval ternary ballots. That is, three options are offered to voters: casting a vote “in favor”, a “neutral” vote or a vote “against” each candidate. We first review desirable properties that a rule aggregating approval-disapproval ternary ballots should satisfy. We check whether the rules that have been proposed in the literature satisfy them. Then, we provide comparable axiomatizations of three rules: one is the lexicographical extension of the Approval rule for binary ballots; the second is the lexicographical extension of the Disapproval rule for binary ballots; and the third rule eliminates candidates with more opponents and fewer supporters than other candidates.The support of the Spanish Ministerio de Economía y Competitividad under project ECO2015-67519-P, and of the Departamento de Educación, Política Lingüística y Cultura from the Basque Government (Research Group IT568-13) is gratefully acknowledged

Neutral candidates in approval and disapproval vote

In this article, the question is to select the “best” candidates within a set of candidates when voters cast approval-disapproval ternary ballots. That is, three options are offered to voters: casting a vote “in favor”, a “neutral” vote or a vote “against” each candidate. We first review desirable properties that a rule aggregating approval-disapproval ternary ballots should satisfy. We check whether the rules that have been proposed in the literature satisfy them. Then, we provide comparable axiomatizations of three rules: one is the lexicographical extension of the Approval rule for binary ballots; the second is the lexicographical extension of the Disapproval rule for binary ballots; and the third rule eliminates candidates with more opponents and fewer supporters than other candidates.The support of the Spanish Ministerio de Economía y Competitividad under project ECO2015-67519-P, and of the Departamento de Educación, Política Lingüística y Cultura from the Basque Government (Research Group IT568-13) is gratefully acknowledged

Dilemma with approval and disapproval votes

International audienc

Dilemma with approval and disapproval rules

Présenté par Stéphane Gonzalez (invité)National audienc

Apparent mismatch between extended X-ray absorption fine structure and difffraction structures of cristalline metastable WO3

International audienc

MnO Conversion Reaction: TEM and EELS Investigation of the Instability under Electron Irradiation

International audienceActive materials in batteries suffer from deleterious chemical and structural evolutions during cycling. To follow these modifications, transmission electron microscopy and associated techniques (EELS, EDX) are of great use. However, these materials can undergo drastic changes under the electron beam. In this study the various microstructural and chemical evolutions induced by electron irradiation were thoroughly investigated at different charging states on a MnO material reacting through the conversion process leading to nanoparticles. During the electron irradiation, compounds pulverization, nanograins growth as well as the formation of manganese carbide were observed. Consequently, knowing the modifications the sample can undergo under electron irradiation and managing to the best the TEM parameters (spot size, aperture size…) to limit its effect can be of help to avoid misinterpretation and to fully understand the mechanisms, which occur during cycling

Electrode contributions to the impedance of a high-energy density Li-ion cell designed for EV applications

International audienceElectrochemical Impedance Spectroscopy (EIS) measurements are performed on a high energy density Li-ion cell, which consists of a graphite-based composite negative electrode, a LiMn2O4-layered oxide blended composite positive electrode, and a carbonate solvents-based electrolyte. Signal analysis is applied to get information regarding cell internal components. The impedance behavior at different states of charge (SOC) is reproduced in an optimized laboratory scaled 3-electrode cell, which enables to: separate each electrode impedance contribution and understand the impedance variations when changing SOC. In the negative electrode, the impedance decreases when increasing SOC because the charge transfer process on the surface of graphite particles becomes less resistive with the lithium content. In the positive electrode, the impedance decreases rapidly at the beginning of charge because at low SOC the EIS response is governed by the layered oxide particles, whose electronic properties strongly depend on the lithium content. Finally, the negative electrode contribution to the total cell impedance varies between 60 and 74%; whereas the positive electrode contribution, being the complement, varies between 40 and 26%

Ethylene bis-carbonates as telltales of SEI and electrolyte health,role of carbonate type and new additives

International audienceThe ethylene bis-carbonate compounds formation is responsible for the earliest change in electrolytecomposition which can be one of the reasons for battery performance decay. In this study, liquid GC/MStechnique is used to detect their formation in electrolytes based on solvent mixtures of EC and differentlinear carbonates (DMC, DEC and EMC), after the first cycle in full cells composed of synthetic graphitepowder/commercial positive films. These compounds stem from linear carbonate electrochemical reduc-tion leading to alkoxide compounds and can be quantified using a selective bicyclic boron ester Lewisacid as an electrolyte additive. Moreover, a quantitative study on ethylene bis-carbonate compounds forwhich the generation profile is different depending on the linear carbonate type, shows that either inbatteries or in a simple chemical mixture of electrolyte and lithium alkoxide, their formation stops whenit reaches a threshold concentration due to the thermodynamic equilibrium. The overall informationis useful for investigating the passivation ability and the dissolution of the Solid Electrolyte Interphase(SEI) that is formed on the negative electrode material. Finally, the passivation property of the SEI freshlyformed with four additives - Vinylene Carbonate (VC), Vinyl Ethylene Carbonate (VEC), Fluoro EthyleneCarbonate (FEC) and 1,3-Propane Sultone (1,3-PS)- is studied