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.

Study on Conductivity of Ceramics LaFe_(1 - x) Ni_xO_(3-δ)

The LaFe 1-x Ni x O 3-δ serial ceramics were prepared by standard solid phase reaction method. Two arm electric bridge principal and four electrode method were adopted to measure the resistivity. The results indicate that LaFe 1-x Ni x O 3-δ ceramics are of metallic state conductivity when x varies from 0 6 to 0 8. There are oxygen vacancies and conductive electrons in the ceramics, which results in highly mixed conductivity of electrons and oxygen ions. The amount of oxygen vacancies depends on the sintering techniques, so the proper increase of sintering temperature can decrease the room temperature resistivity. A phase transition is found at around 120 K in the low temperature experiment.

Hydrogen production at intermediate temperatures with proton conducting ceramic cells:Electrocatalytic activity,durability and energy efficiency

Proton conducting ceramic cells(PCCs)are an attractive emerging technology operating in the intermediate temperature range of 500 to 700℃.In this work,we evaluate the production of hydrogen at intermediate temperatures by proton conducting ceramic cell electrolysis(PCCEL).We demonstrate a highperformance steam electrolysis owing to a composite positrode based on BaGd_(0.8)La_(0.2)Co_(2)O_(6-δ)(BGLC1082)and BaZr0.5Ce0.4Y0.1O3-δ(BZCY541).The high reliability of PCCEL is demonstrated for 1680 h at a current density as high as-0.8 A cm^(-2)close to the thermoneutral cell voltage at 600℃.The electrolysis cell showed a specific energy consumption ranging from 54 to 66 kW h kg^(-1)that is comparable to state-of-the-art low temperature electrolysis technologies,while showing hydrogen production rates systematically higher than commercial solid oxide ceramic cells(SOCs).Compared to SOCs,the results verified the higher performances of PCCs at the relevant operating temperatures,due to the lower activation energy for proton transfer comparing with oxygen ion conduction.However,because of the p-type electronic conduction in protonic ceramics,the energy conversion rate of PCCs is relatively lower in steam electrolysis.The faradaic efficiency of the PCC in electrolysis mode can be increased at lower operating temperatures and in endothermic conditions,making PCCEL a technology of choice to valorize high temperature waste heat from industrial processes into hydrogen.To increase the faradaic efficiency by optimizing the materials,the cell design,or the operating strategy is a key challenge to address for future developments of PCCEL in order to achieve even more superior techno-economic merits.

Characteristic Analysis of the Solid Oxide Fuel Cell with Proton Conducting Ceramic Electrolyte

An electrolyte model for the solid oxide fuel cell (SOFC) with proton conducting perovskite electrolyte is developed in this study, in which four types of charge carriers including proton, oxygen vacancy (oxide ion), free electron and electron hole are taken into consideration. The electrochemical process within the SOFC with hydrogen as the fuel is theoretically analyzed. With the present model, the effects of some parameters, such as the thickness of electrolyte, operating temperature and gas composition, on the ionic transport (or gas permeation) through the electrolyte and the electrical performance, i.e., the electromotive force (EMF) and internal resistance of the cell, are investigated in detail. The theoretical results are tested partly by comparing with the experimental data obtained from SrCe0.95M0.05O3-α, (M=Yb, Y) cells.

Nanocomposite Membranes based on Perfl uorosulfonic Acid/Ceramic for Proton Exchange Membrane Fuel Cells

Perfl uorosulfonic acid/ceramic nanocomposite membranes were investigated as electrolytes for polymer electrolyte membrane fuel cell applications under low relative humidity. Different nanosized ceramics（SiO2, ZrO2, TiO2） with diameters in the range of 2-6 nm were synthesized in situ in Nafion solution through a sol-gel process and the formed nanosized ceramics were well-dispersed in the solution.The nanocomposite membranes were formed through a casting process. The nanocomposite membrane showes enhanced water retention ability and improved proton conductivity compared to those of pure Nafi on membrane. The mechanical strength of the formed nanocomposite membranes is slightly less than that of pure Nafi on membrane. The experimental results demonstrate that the polymer ceramic nanocompsite membranes are potential electrolyte for fuel cells operating at elevated temperature.

Influence of dopant concentration on the transparent and thermal properties of Nd_2O_3-doped alumina translucent ceramics

The transparent and thermal developments of high-purity Al_2O_3 doped with different levels of Nd_2O_3 were investigated. Dopant levels ranged from 500–1500 ppm（Nd/Al atomic ratio）. The samples were characterized with X-ray diffraction（XRD）, scanning electron microscopy（SEM）, Raman spectroscopy, transmittance spectroscopy and specific heat measurement. Results revealed that with proper Nd doped, Nd^（3＋） ions solid dissolved in Al_2O_3 lattice, resulting in small and uniform grain and high bonding vibration, which was beneficial to transparent and thermal properties. With 1000 ppm Nd doped, Al_2O_3 translucent ceramics showed a total transmittance of 89% and thermal conductivity of 41.7 W/m/K, indicating a potential application as substrate for effective heat dissipation and multi emitting surface in LEDs module.

(Cr_(0.2)Mn_(0.2)Fe_(0.2)Co_(0.2)Mo_(0.2))B:A novel high-entropy monoboride with good electromagnetic interference shielding performance in K-band

A novel equimolar high-entropy(HE)transition metal monoboride,(Cr_(0.2)Mn_(0.2)Fe_(0.2)Co_(0.2)Mo_(0.2))B,was designed and prepared in powder and bulk form by high temperature elemental reaction method and spark plasma sintering(SPS)method,respectively.XRD analysis shows that HE(Cr_(0.2)Mn_(0.2)Fe_(0.2)Co_(0.2)Mo_(0.2))B possesses orthorhombic structure with Pnma space group.Through Rietveld refinement,the lattice parameters of HE(Cr_(0.2)Mn_(0.2)Fe_(0.2)Co_(0.2)Mo_(0.2))B are a=5.6675,b=2.9714,c=4.2209 and the theoretical density is 6.95 g/cm~3.The Vickers hardness and electrical conductivity of HE(Cr_(0.2)Mn_(0.2)Fe_(0.2)Co_(0.2)Mo_(0.2))B bulk with relative density of 90%is 12.3±0.5 GPa and 0.49±0.04×10~6 S/m,respectively.Due to high electrical conductivity,HE(Cr_(0.2)Mn_(0.2)Fe_(0.2)Co_(0.2)Mo_(0.2))B bulk with 3.0 mm thickness displays superior EMI shielding performance in 18.0–26.5 GHz(K-band),and the average values of SET,SER,and SEAare 23.3 dB,13.9 dB,and 9.4 dB,respectively.The EMI shielding mechanism of HE(Cr_(0.2)Mn_(0.2)Fe_(0.2)Co_(0.2)Mo_(0.2))B mainly results from reflection.

Highly Stable Silicon–Carbon–Nitrogen Composite Anodes from Silsesquiazane for Rechargeable Lithium-Ion Battery

Herein, we developed novel silicon-carbon-nitrogen （SiCN） composites synthesized by pyrolyzing silsesquiazane polymer as an anode material for rechargeable lithium-ion batteries. Among variable pyrolysis temperatures of 700 ℃, 1000 ℃ and 1300 ℃, the SiCN composites prepared at 1000 ℃ showed the highest capacity with outstanding battery cycle life by cyclic voltammetry and electrochemical impedance spectroscopy. Such good battery and electrochemical performances should be attributed to a proper ratio of carbon and nitrogen or oxygen in the SiCN composites. Furthermore, our SiCN electrode possessed better lithium ion conductivity than pure silicon nanoparticles. This work demonstrates that polymer-derived composites are among the promising strategies to achieve highly stable silicon anodes for rechargeable batteries.