Electrochemical Kinetic Modulators in Lithium–Sulfur Batteries:From Defect-Rich Catalysts to Single Atomic Catalysts

Lithium–sulfur batteries exhibit unparalleled merits in theoretical energy density(2600 W h kg^(-1))among next-generation storage systems.However,the sluggish electrochemical kinetics of sulfur reduction reactions,sulfide oxidation reactions in the sulfur cathode,and the lithium dendrite growth resulted from uncontrollable lithium behaviors in lithium anode have inhibited high-rate conversions and uniform deposition to achieve high performances.Thanks to the“adsorption-catalysis”synergetic effects,the reaction kinetics of sulfur reduction reactions/sulfide oxidation reactions composed of the delithiation of Li_(2)S and the interconversions of sulfur species are propelled by lowering the delithiation/diffusion energy barriers,inhibiting polysulfide shuttling.Meanwhile,the anodic plating kinetic behaviors modulated by the catalysts tend to uniformize without dendrite growth.In this review,the various active catalysts in modulating lithium behaviors are summarized,especially for the defect-rich catalysts and single atomic catalysts.The working mechanisms of these highly active catalysts revealed from theoretical simulation to in situ/operando characterizations are also highlighted.Furthermore,the opportunities of future higher performance enhancement to realize practical applications of lithium–sulfur batteries are prospected,shedding light on the future practical development.

Intrinsic electrochemical activity modulation of MOF-derived C/N-NiCoMn-LDH/Ag electrode for low temperature hybrid supercapacitors

Layered double hydroxides(LDHs)are promising electrode candidates for supercapacitors.However,lim-itations like inferior cycling stability and unsatisfactory charge storage capability at low temperatures have exerted negative effects on their applications.Herein,a novel synthetic process has been elaborately designed and provided to have the composition and structure of the C/N-NiCoMn-LDH/Ag(C/N-CNMA)delicately regulated.Both the experimental and theoretical researches unveil that the incorporated manganese species and elemental silver could dramatically modulate the bandgap,crystallinity and surface electron structure of the LDH,leading to the remarkable improvement in its conductivity,exposed active sites and intrinsic electrochemical activity,and thus the OH^(*)and O^(*)adsorption free energy could be remarkably optimized,even at low temperatures.In addition,the low crystallinity C/N-CNMA is of great electrochemical compatibility with both the KOH aqueous electrolyte and the isobutyl alcohol(IPA)modulated organohydrogel electrolyte.By means of adjusting the solvation and hydrogen bonding in the electrolytes,the assembled hybrid supercapacitors deliver excellent energy density,power density and cycling stability in the temperature range of-30 to 25℃.Specifically,the gel electrolyte with IPA as the anti-freezing functional additive displays high flexibility and ionic conductivity at low temperatures.

Corrosion inhibition of carbon steel in hydrochloric acid by cationic arylthiophenes as new eco-friendly inhibitors: Experimental and quantum chemical study

This study describes the adsorption behavior of three arylthiophene derivatives namely:2-(4-amidino-3-fluorophenyl)-5-[4-methoxy phenyl] thiophene dihydrochloride salt(MA-1217),2-(4-amidinophenyl)-5-[4-chlorophenyll thiophene dihydrochloride salt(MA-1316) and 2-(4-amidino-3-fluorophenyl)-5-[4-ch lorophenyllthiophene dihydrochloride salt(MA-1312) at C-steel in 1.0 mol·L^(-1) HCl interface using experimental and theoretical studies.Electrochemical and mass loss measurements showed that the inhibition efficiency(IE) of the arylthiophene derivatives increases with increasing concentrations and exhibited maximum efficiency 89% at 21×10^(-6) mol·L^(-1)(MA-1217) by mass loss method.The investigated arylthiophene derivatives obey the Langmuir adsorption isotherm.From polarization studies the arylthiophene derivatives act as mixed-type inhibitors.Surface analysis were carried out and discussed.The mode of orientation and adsorption of inhibitor molecules on C-steel surface was studied using molecular dynamics(MD) simulations.Quantum chemical parameters as well as the radial distribution function indices and binding energies confirm the experimental results.

All-solid-state carbon-nanotube-fiber-based finger-muscle and robotic gripper

Carbon nanotube fibers(CNTFs)have many desirable properties such as lightweight,high strength,high conductivity,and long lifetimes.Coiled CNTF is an ideal material for preparing electrochemically driven artificial muscles.While previous studies focused mainly on the actuation performance of artificial muscles made of CNTF,this study focuses on an actuator that mimics human finger movements(flexion).More specifically,the preparation of CNTF muscles were optimized by twisting with weight.Then,actuators are designed and assembled by combining all-solid-state CNTF muscles with polypropylene(PP)sheets.Moreover,a dualelectrode system,which is infiltrated by a gel electrolyte,is built into the muscle actuator.In addition,a robotic gripper is fabricated,which uses these actuators.This study can help improve the design of CNTF-based muscle-actuators and future applications in robotics.