Enabling an Inorganic-Rich Interface via Cationic Surfactant for High-Performance Lithium Metal Batteries

An anion-rich electric double layer(EDL)region is favorable for fabricating an inorganic-rich solid-electrolyte interphase(SEI)towards stable lithium metal anode in ester electrolyte.Herein,cetyltrimethylammonium bromide(CTAB),a cationic surfactant,is adopted to draw more anions into EDL by ionic interactions that shield the repelling force on anions during lithium plating.In situ electrochemical surface-enhanced Raman spectroscopy results combined with molecular dynamics simulations validate the enrichment of NO_(3)^(−)/FSI−anions in the EDL region due to the positively charged CTA^(+).In-depth analysis of SEI structure by X-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectrometry results confirmed the formation of the inorganic-rich SEI,which helps improve the kinetics of Li^(+)transfer,lower the charge transfer activation energy,and homogenize Li deposition.As a result,the Li||Li symmetric cell in the designed electrolyte displays a prolongated cycling time from 500 to 1300 h compared to that in the blank electrolyte at 0.5 mA cm^(-2) with a capacity of 1 mAh cm^(-2).Moreover,Li||LiFePO_(4) and Li||LiCoO_(2) with a high cathode mass loading of>10 mg cm^(-2) can be stably cycled over 180 cycles.

From Micropores to Ultra-micropores inside Hard Carbon: Toward Enhanced Capacity in Room-/ Low-Temperature Sodium-Ion Storage

Pore structure of hard carbon has a fundamental influence on the electrochemical properties in sodium-ion batteries(SIBs).Ultra-micropores(<0.5 nm)of hard carbon can function as ionic sieves to reduce the diffusion of slovated Na+but allow the entrance of naked Na^(+) into the pores,which can reduce the interficial contact between the electrolyte and the inner pores without sacrificing the fast diffusion kinetics.Herein,a molten diffusion-carbonization method is proposed to transform the micropores(>1 nm)inside carbon into ultra-micropores(<0.5 nm).Consequently,the designed carbon anode displays an enhanced capacity of 346 mAh g^(−1) at 30 mA g^(−1) with a high ICE value of~80.6%and most of the capacity(~90%)is below 1 V.Moreover,the high-loading electrode(~19 mg cm^(−2))exhibits a good temperature endurance with a high areal capacity of 6.14 mAh cm^(−2) at 25℃ and 5.32 mAh cm^(−2) at −20℃.Based on the in situ X-ray diffraction and ex situ solid-state nuclear magnetic resonance results,the designed ultra-micropores provide the extra Na+storage sites,which mainly contributes to the enhanced capacity.This proposed strategy shows a good potential for the development of high-performance SIBs.

Carbon-based flexible self-supporting cathode for lithium-sulfur batteries:Progress and perspective

The flexible self-supporting electrode can maintain good mechanical and electrical properties while retaining high specific capacity,which meets the requirements of flexible batteries.Lithium-sulfur batteries(LSBs),as a new generation of energy storage system,hold much higher theoretical energy density than traditional batteries,and they have attracted extensive attention from both the academic and industrial communities.Selection of a proper substrate material is important for the flexible self-supporting electrode.Carbon materials,with the advantages of light weight,high conductivity,strong structural plasticity,and low cost,provide the electrode with a large loading space for the active material and a conductive network.This makes the carbon materials meet the mechanical and electrochemical requirements of flexible electrodes.In this paper,the commonly used fabrication methods and recent research progresses of the flexible self-supporting cathode with a carbon material as the substrate are introduced.Various sulfur loading methods are summarized,which provides useful information for the structural design of the cathode.As the first review article of the carbon-based flexible self-supporting LSB cathodes,it provides valuable guidance for the researchers working in the field of LSB.

Endothelial surface glycocalyx and vascular mechano-sensing and transduction

Introduction The endothelial cells(ECs)lining every blood vessel wall constantly expose to the mechanical forces generated by the blood flow.The EC responses to these hemodynamic forces play a critical role in the homeostasis of the circulatory system.In addition to forming a transport barrier between the blood and vessel wall,vascular ECs play important roles in regulating circulation functions.Besides biochemical stimuli,blood flow induced(hemodynamic)mechanical stimuli,such as shear stress,pressure and circumferential stretch,modulate EC morphology and functions by activating mechanosensors,signaling pathways,and gene and protein expressions.The EC responses to the hemodynamic forces(mechano-sensing and transduction)

Engineering Cu_(1.96)S/Co_(9)S_(8) with sulfur vacancy and heterostructure as an efficient bifunctional electrocatalyst for water splitting

Defect and interface engineering have been recognized as efficient strategies for developing high-performance electrocatalysts.However,it is still challenging to couple defect and interface engineering in transition metal sulfides and understand their dynamic evolution process during electrocatalysis.Herein,we developed one-step pyrolysis of bimetallic sulfide to construct S vacancy-rich Cu_(1.96)S/Co_(9)S_(8) heterostructure by controlling the critical decomposition temperature.The as-synthesized Cu_(1.96)S/Co_(9)S_(8) exhibits excellent bifunctional electrocatalytic performance,with a low overpotential of 99 and 200 mV at 10 mA cm−2 towards hydrogen evolution reaction(HER)and oxygen evolution reaction(OER)in 1.0 mol/L KOH electrolyte,respectively.A symmetric two-electrode cell with Cu_(1.96)S/Co_(9)S_(8) delivered a current density of 10 mA cm^(−2) at a low voltage of 1.43 V and showed long-term stability for 200 h.A series of in/ex-situ techniques revealed that the electrochemical reconfiguration only appeared in the OER process,resulting in the CoOOH/CuO and SO42−species promoting OER performance.Meanwhile,the S vacancy and heterostructure interface in Cu_(1.96)S/Co_(9)S_(8) were proved to optimize the electronic structure and the adsorption of intermediates for HER by density function theory(DFT)simulations.This work provides a promising strategy to construct metal sulfides with rich defects and heterogeneous interfaces and understand their dynamic evolution process for electrochemical storage and conversion devices.

An in-situ spectroscopy investigation of alkali metal interaction mechanism with the imide functional group

Organic anode materials have attracted considerable interest owing to their high tunability by adopting various active functional groups.However,the interaction mechanisms between the alkali metals and the active functional groups in host materials have been rarely studied systematically.Here,a widely used organic semiconductor of perylene-3,4,9,10-tetracarboxylic diimide(PTCDI)was selected as a model system to investigate how alkali metals interact with imide functional groups and induce changes in chemical and electronic structures of PTCDI.The interaction at the alkali/PTCDI interface was probed by in-situ X-ray photoelectron spectroscopy(XPS),ultraviolet photoelectron spectroscopy(UPS),synchrotron-based near edge X-ray absorption fine structure(NEXAFS),and corroborated by density functional theory(DFT)calculations.Our results indicate that the alkali metal replaces the hydrogen atoms in the imide group and interact with the imide nitrogen of PTCDI.Electron transfer induced gap states and downward band-bending like effects are identified on the alkali-deposited PTCDI surface.It was found that Na shows a stronger electron transfer effect than Li.Such a model study of alkali insertion/intercalation in PTCDI gives insights for the exploration of the potential host materials for alkali storage applications.

One-step synthesis of hierarchically porous hybrid TiO2 hollow spheres with high photocatalytic activity

Hierarchically porous hybrid TiO2 hollow spheres were solvothermally synthesized successfully by using tetrabutyl titanate as titanium precursor and hydrated metal sulfates as soft templates. The as-prepared TiO2 spheres with hierarchically pore structures and high specific surface area and pore volume consisted of highly crystallized anatase TiO2 nanocrystals hybridized with a small amount of metal oxide from the hydrated sulfate. The proposed hydrated-sulfate assisted solvothermal （HAS） synthesis strategy was demonstrated to be widely applicable to various systems. Evaluation of the hybrid TiO2 hollow spheres for the photo-decomposition of methyl orange （MO） under visible-light irradiation revealed that they exhibited excellent photocatalytic activity and durability.

Probing fluorination promoted sodiophilic sites with model systems of F_(16)CuPc and CuPc

Sodium metal batteries(SMBs)are receiving broad attention due to the high specific capacity of sodium metal anodes and the material abundance on earth.However,the growth of dendrites results in poor battery performance and severe safety problems,inhibiting the commercial application of SMBs.To stabilize sodium metal anodes,various methods have been developed to optimize the solid electrolyte interphase(SEI)layer and adjust the electroplating/stripping behavior of sodium.Among the methods,developing anode host materials and adding electrolyte additives to build a protective layer are promising and convenient.However,the understanding of the interaction process between sodium metal and those organic materials is still limited,but is essential for the rational design of advanced anode hosts and electrolyte additives.In this study,we use copper(II)hexadecafluorophthalocyanine(F_(16)CuPc),and copper(II)phthalocyanine(CuPc),as model systems to unravel the sodium interaction with polar functional groups by in-situ photoelectron spectroscopy and density functional theory(DFT)calculations.It is found that sodium atoms prefer to interact with the inner pyrrolic nitrogen sites of CuPc,while they prefer to interact with the outer aza bridge nitrogen atoms,owing to Na-F interaction at the Na/F_(16)CuPc interface.Besides,for the both organic molecules,the central Cu(II)ions are reduced to Cu(I)ions by charge transfer from deposited sodium.The fluorine-containing groups are proven to promote the interaction process of sodium in organic materials,which sheds light on the design of functional interfaces in host materials and anode protective layers for sodium metal anodes.