Minimizing Carbon Content with Three-in-One Functionalized Nano Conductive Ceramics:Toward More Practical and Safer S Cathodes of Li-S Cells

Using porous carbon hosts in cathodes of Li-S cells can disperse S actives and offset their poor electrical conductivity.However,such reservoirs would in turn absorb excess electrolyte solvents to S-unfilled regions,causing the electrolyte overconsumption,specific energy decline,and even safety hazards for battery devices.To build better cathodes,we propose to substitute carbons by In-doped SnO_(2)(ITO)nano ceramics that own three-in-one functionalities:1)using conductive ITO enables minimizing the total carbon content to an extremely low mass ratio(~3%)in cathodes,elevating the electrode tap density and averting the electrolyte overuse;2)polar ITO nanoclusters can serve as robust anchors toward Li polysulfide(LiPS)by electrostatic adsorption or chemical bond interactions;3)they offer catalysis centers for liquid–solid phase conversions of S-based actives.Also,such ceramics are intrinsically nonflammable,preventing S cathodes away from thermal runaway or explosion.These merits entail our configured cathodes with high tap density(1.54 g cm^(−3)),less electrolyte usage,good security for flame retardance,and decent Li-storage behaviors.With lean and LiNO_(3)-free electrolyte,packed full cells exhibit excellent redox kinetics,suppressed LiPS shuttling,and excellent cyclability.This may trigger great research enthusiasm in rational design of low-carbon and safer S cathodes.

Mechanical Study of Nano⁃ceramic Thermal Barrier Coatings by the Equation of Phonon Radiative Transfer

Temperature filed,thermal stress,especially tensile stress and J⁃integral are important for thermal barrier coatings(TBCs)under thermal shock.At the micro⁃and nano⁃scale,the energy transport mechanisms are significantly different from those at the macro⁃scale.The temperature fields,which are obtained by combining the Equation of Phonon Radiative Transport(EPRT)(for the nano⁃scale ceramic TBCs)and the Fourier law(for the substrate),are used as the thermal loading in the thermal stress and J⁃integral of an edge in the TBCs analysis by the finite element method.The temperature field and thermal stresses as well as J⁃integral are compared with those which are calculated by applying the Fourier law to both the TBCs and the substrate.The influence of the physical heat properties of the TBCs on the temperature field and thermal stress and J⁃integral have been analyzed in this paper.It is concluded that the temperature,thermal stress,including the tensile and compressive components,and J⁃integral which are calculated with the EPRT,are lower than that calculated with the Fourier law in the TBCs.Moreover,thermal stress in the TBCs increase with increasing phonon speed and relaxation time,but J⁃integral at the crack tip is in the opposite.