In Situ-Constructed Li_(x)MoS_(2)with Highly Exposed Interface Boosting High-Loading and Long-Life Cathode for All-Solid-State Li-S Batteries

As the persistent concerns regarding sluggish reaction kinetics and insufficient conductivities of sulfur cathodes in all-solid-state Li-S batteries(ASSLSBs),numerous carbon additives and solid-state electrolytes(SSEs)have been incorporated into the cathode to facilitate ion/electron pathways around sulfur.However,this has resulted in a reduced capacity and decomposition of SSEs.Therefore,it is worth exploring neotype sulfur hosts with electronic/ionic conductivity in the cathode.Herein,we present a hybrid cathode composed of few-layered S/MoS_(2)/C nanosheets(<5 layers)that exhibits high-loading and long-life performance without the need of additional carbon additives in advanced ASSLSBs.The multifunctional MoS_(2)/C host exposes the abundant surface for intimate contacting sites,in situ-formed LixMoS_(2)during discharging as mixed ion/electron conductive network improves the S/Li2S conversion,and contributes extra capacity for the part of active materials.With a high active material content(S+MoS_(2)/C)of 60 wt%in the S/MoS_(2)/C/Li_(6)PS_(5)Cl cathode composite(the carbon content is only~3.97 wt%),the S/MoS_(2)/C electrode delivers excellent electrochemical performance,with a high reversible discharge capacity of 980.3 mAh g^(-1)(588.2 mAh g^(-1)based on the whole cathode weight)after 100 cycles at 100 mA g^(-1).The stable cycling performance is observed over 3500 cycles with a Coulombic efficiency of 98.5%at 600 mA g^(-1),while a high areal capacity of 10.4 mAh cm^(-2)is achieved with active material loading of 12.8 mg cm^(-2).

Mixed Conduction in BaCe0.8Pr0.2O3-α Ceramic

BaCe0.8Pr0.2O3-α ceramic was synthesized by high temperature solid-state reaction. The structural characteristics and the phase purity of the crystal were determined using powder X-ray diffraction analysis. By using the methods of AC impedance spectroscopy, gas concentration cell and electrochemical pumping of hydrogen, the conductivity and ionic transport number of BaCe0.8Pr0.2O3-α were measured, and the electrical conduction behavior of the material was investigated in different gases in the temperature range of 500-900℃. The results indicate that the material was of a single perovskite-type orthorhombic phase. From 500℃ to 900 ℃, electronic-hole conduction was dominant in dry and wet oxygen, air or nitrogen, and the total conductivity of the material increased slightly with increasing oxygen partial pressure in the oxygen partial pressure range studied. Ionic conduction was dominant in wet hydrogen, and the total conductivity was about one or two orders of magnitude higher than that in hydrogen-free atmosphere （oxygen, air or nitrogen）

Protonic and Electronic Conductivities and Hydrogen Permeation of SrCe0.95-xZrxTm0.05O3-δ（0≤x≤0.40） Membrane

Zr-substituted,Tm-doped SrCeO3（SrCe0.95-xZrxTm0.05O3-δ,0≤x≤0.40）were synthesized via citrate complexing method,and the membranes of SrCe0.95-xZrxTm0.05O3-δwere prepared by pressing followed by sintering. X-ray diffraction（XRD）was used to characterize the phase structure of sintered membrane.The microstructure of the sintered membranes was studied by scanning electron microscopy（SEM）.Protonic and electronic conductivities were measured under different circumstance.Hydrogen permeation through the SrCe0.75Zr0.20Tm0.05O3-δmembranes was carried out using gas permeation setup.Hydrogen permeation fluxes（ 2H J）of the SrCe0.75Zr0.20Tm0.05O3-δ membrane reach up to 0.042 ml·min^ -1 ·cm^-2 at H 2 partial pressure of 0.4×10 ^5 Pa at 900°C.The hydrogen permea- tion fluxes（ 2H J）obtained in this paper are slightly lower than that of SrCe0.95Tm0.05O3-δon the same orders,and Zr doping can increase chemical stability of the SrCe0.75Zr0.20Tm0.05O3-δmembranes.

Spin pumping at the Co_2 FeAl_(0.5)Si_(0.5)/Pt interface

Spin pumping at the Co2FeAl0.5Si0.5/Pt and Pt/Co2FeAl0.5Si0.5 interfaces has been studied by ferromagnetic resonance technology(FMR). The spin mixing conductance of the Co2FeAl0.5Si0.5/Pt and Pt/Co2FeAl0.5Si0.5 interfaces was determined to be 3.7×1019m 2and 2.1×1019m 2 by comparing the Gilbert damping in a Co2FeAl0.5Si0.5single film, Co2FeAl0.5Si0.5/Pt bilayer film and a Pt/Co2FeAl0.5Si0.5/Pt trilayer film. Spin pumping is more efficient in the Co2FeAl0.5Si0.5/Pt bilayer film than in permalloy/Pt bilayer film.

CONDUCTING BLENDS OF POLY (2-VINYL PYRIDINE) AND POLYETHYLENE OXIDE WITH HIGH MOLECULAR WEIGHT

Ionic, electronic and mixed (ionic-electronic) conductivities of blends of poly(2-vinyl pyridine) (P2VP) and poly(ethylene oxide) (PEO) with high molecular weight after doped with LiClO4, TCNQ or LiClO4 and TCNQ were investigated. Effects of LiClO4 and TCNQ concentrations on the conductivity of PEO/P2VP/LiClO4 or TCNQ blend were studied. The ionic conductivity of PEO/P2VP/LiClO4 blend increases with increasing PEO content. At a Li/ethylene bride molar ratio of 0.10 and a TCNQ/2-vinyl pyridine molar ratio of 0.5, the mixed conductivity of PEO/P2VP/LiClO4/TCNQ is higher than the total of ionic conductivity of PEO/P2VP/LiClO4 and electronic conductivity of PEO/P2VP/TCNQ when the weight ratio of PEO and P2VP is 6/4 or 5/5. Scanning electron microscopy (SEM) on the broken cross-section of the PEO/P2VP/LiClO4 blend and differential scanning calorimetry (DSC) results show that LiClO4 could act as a compatibilizer in the blend.

High-capacity,high-rate,and dendrite-free lithium metal anodes based on a 3D mixed electronic-ionic conductive and lithiophilic scaffold

Lithium metal anode possesses a high theoretical capacity and the lowest redox potential,while the severe growth of Li dendrite prevents its practical application.Herein,we prepared a structure of Li_(3)P nanosheets and Ni nanoparticles decorated on Ni foam(NF)as a three-dimensional(3 D)scaffold for dendrite-free Li metal anodes(Li-Li_(3)P/Ni@Ni foam anodes,shortened as L-LPNNF)using a facile melting method.The LiP nanosheets exhibit excellent Li-ion conductivity as well as superior lithiophilicity,and the 3 D nickel scaffold provides sufficient electron conductivity and ensures structure stability.Therefore,symmetric cells assembled by L-LPNNF possess lowered voltage hysteresis and improved long cycle stability(a voltage hysteresis of 104.2 mV after 500 cycles at a high current density of 20 mA cm^(-2) with a high capacity of 10 mA h cm^(-2)),compared with the cells assembled with Li foil or Li-NF anodes.Furthermore,the full cells with paired L-LPNNF anodes and commercial LiFePOcathodes suggest a specific capacity of 124.6 mA h gand capacity retention of 90.8%after 180 cycles with the Coulombic efficiency(CE)of~100%at a current rate of 1 C.This work provides a potentially scalable option for preparing a mixed electronic-ionic conductive and lithiophilic scaffold for dendrite-free Li anodes at high current densities.

Enhancing proton exchange membrane water electrolysis by building electron/proton pathways

Proton exchange membrane water electrolysis(PEMWE)plays a critical role in practical hydrogen production.Except for the electrode activities,the widespread deployment of PEMWE is severely obstructed by the poor electron-proton permeability across the catalyst layer(CL)and the inefficient transport structure.In this work,the PEDOT:F(Poly(3,4-ethylenedioxythiophene):perfluorosulfonic acid)ionomers with mixed proton-electron conductor(MPEC)were fabricated,which allows for a homogeneous anodic CL structure and the construction of a highly efficient triple-phase interface.The PEDOT:F exhibits strong perfluorosulfonic acid(PFSA)side chain extensibility,enabling the formation of large hydrophilic ion clusters that form proton-electron transport channels within the CL networks,thus contributing to the surface reactant water adsorption.The PEMWE device employing membrane electrode assembly(MEA)prepared by PEDOT:F-2 demonstrates a competitive voltage of 1.713 V under a water-splitting current of 2 A cm^(-2)(1.746 V at 2A cm^(-2) for MEA prepared by Nafion D520),along with exceptional long-term stability.Meanwhile,the MEA prepared by PEDOT:F-2 also exhibits lower ohmic resistance,which is reduced by 23.4%and 17.6%at 0.1 A cm^(-2) and 1.5 A cm^(-2),respectively,as compared to the MEA prepared by D520.The augmentation can be ascribed to the superior proton and electron conductivity inherent in PEDOT:F,coupled with its remarkable structural stability.This characteristic enables expeditious mass transfer during electrolytic reactions,thereby enhancing the performance of PEMWE devices.

Metal-nitrogen-doped hybrid ionic/electronic conduction triple-phase interfaces for high-performance all-solid-state lithium-sulfur batteries

The point-to-point contact mechanism in all-solid-state Li-S batteries(ASSLSBs)is not as efficient as a liquid electrolyte which has superior mobility in the electrode,resulting in a slower reaction kinetics and inadequate ionic/electronic conduction network between the S(or Li_(2)S),conductive carbon,and solid-state electrolytes(SSEs)for achieving a swift(dis)charge reaction.Herein,a series of hybrid ionic/electronic conduction triple-phase interfaces with transition metal and nitrogen co-doping were designed.The graphitic ordered mesoporous carbon frameworks(TM-N-OMCs;TM=Fe,Co,Ni,and Cu)serve as hosts for Li_(2)S and Li_(6)PS_(5)Cl(LPSC)and provide abundant reaction sites on the triple interface.Results from both experimental and computational research display that the combination of Cu-N co-dopants can promote the Li-ion diffusion for rapid transformation of Li_(2)S with adequate ionic(6.73×10^(−4)S·cm^(−1))/electronic conductivities(1.77×10^(−2)S·cm^(−1))at 25℃.The as-acquired Li_(2)S/Cu-N-OMC/LPSC electrode exhibits a high reversible capacity(1147.7 mAh·g^(−1))at 0.1 C,excellent capacity retention(99.5%)after 500 cycles at 0.5 C,and high areal capacity(7.08 mAh·cm^(−2)).

Synthesis and characterization of calcium and manganese-doped rare earth oxide La_(1-x)Ca_xFe_(0.9)Mn_(0.1)O_(3-δ) for cathode material in IT-SOFC

In order to develop novel cathode materials with high performance for intermediate temperature SOFC（IT-SOFC）,Ca and Mn doped rare earth oxides La1-xCaxFe0.9Mn0.1O3-δ（x=0.1,0.3 and 0.5,denoted as LCFM9191,LCFM7391 and LCFM5591） were synthesized by solid state reaction（SSR） method.The formation process,phase structure and microstructure of the synthesized samples were characterized using thermogravimetry/differential scanning calorimetry（TG/DSC）,X-ray diffraction（XRD） and scanning electron microscopy（SEM）.The thermal expansion coefficients（TEC） of the samples were analyzed at 100-900 oC by thermal dilatometry.The electrical conductivities of the samples were measured with direct current（DC） four-terminal method from 300 to 850 oC.The results indicated that the samples（x=0.1 and 0.3） exhibited a single phase with orthorhombic and cubic perovskite structure,respectively after being sintered at 1200 oC for 3 h.The electrical conductivity of the samples increased with temperature up to a maximum value,and then decreased.The small polaron hopping was regarded as the conducting mechanism for synthesized samples at T≤600 oC.The negative temperature dependence occurring at higher temperature was due to the creation of oxygen vacancies for charge balance.LCFM7391 had higher mixed conductivity（100 S/cm） at intermediate temperature and could meet the demand of cathode material for IT-SOFC.In addition,the average TECs of LCFM9191 and LCFM7391 were 11.9×10-6 and 13.1×10-6 K-1,respectively,which had good thermal match to the common electrolytes.

Limiting current oxygen sensor based on Y,In co-doped SrTiO_(3)as a dense diffusion barrier layer

A novel dense diffusion barrier material(Y_(x)Sr_(1−x)Ti_(0.9)In_(0.1)O_(3−δ)(x=0.03,0.05,0.07))was prepared by using a sol-gel method.The crystal structure,microstructures,electrical conductivity and ionic conductivity of barrier material were characterized.The results show that the samples exhibit the formation of cubic perovskite structure phase.The increase of Y-doping amount on A-site improved electrical conductivity and sinterability of materials.A limiting current oxygen sensor based on Y_(0.07)Sr_(0.97)Ti_(0.9)In_(0.1)O_(3–δ)as a dense diffusion barrier shows excellent sensing performance.The linear relationship between limiting current logIL and 1000/T can described logIL=4.603,8−3.847,5·1,000/T.At 750°C,0.25%≤x(O_(2))≤5.0%,the linear relationship between limiting current(IL)and oxygen amount(x(O_(2)))can described as I_(L)=7.047,6+3.875,1·x(O_(2)).