Controllable fabrication of FeCoS_(4) nanoparticles/S-doped bowl-shaped hollow carbon as efficient lithium storage anode

To address the low conductivity and easy agglomeration of transition metal sulfide nanoparticles,FeCoS_(4) nanoparticles embedded in S-doped hollow carbon(FeCoS_(4)@S-HC)composites were successfully fabricated through a combination of hydrothermal processes and sulfidation treatment.The unique bowlshaped FeCoS_(4)/S-HC composites exhibit excellent structural stability with a high specific surface area of 303.7 m^(2)·g^(-1) and a pore volume of 0.93 cm^(3)·g^(-1).When applied as anode material for lithium-ion batteries,the FeCoS_(4)@S-HC anode exhibits efficient lithium storage with high reversible specific capacity(970.2 mA·h·g^(-1) at 100 mA·g^(-1))and enhanced cycling stability(574 mA·h·g^(-1) at 0.2 A·g^(-1) after 350 cycles,a capacity retention of 84%).The excellent lithium storage is attributed to the fact that the bimetallic FeCoS_(4) nanoparticles with abundant active sites can accelerate the electrochemical reaction kinetics,and the bowl-shaped S-HC structure can provide a stable mechanical structure to suppress volume expansion.

Zephyranthes-like Co2NiSe4 arrays grown on 3D porous carbon frame-work as electrodes for advanced supercapacitors and sodium-ion batteries

Developing suitable electrode materials for electrochemical energy storage devices by biomorph assisted design has become a fascinating topic due to the fantastic properties derived from bio-architectures.Herein,zephyranthes-like Co_(2)NiSe_(4)arrays grown on butterfly wings derived three-dimensional(3D)carbon framework(Z-Co_(2)NiSe_(4)/BWC)is fabricated via hydrothermal assembly and further conversion method.Benefiting from its unique structure and multi-components,the obtained Z-Co_(2)NiSe_(4)/BWC electrode for supercapacitor delivers an excellent specific capacitance of 2,280 F·g^(-1)at 1 A·g^(-1).Impressively,the constructed asymmetric supercapacitor using Co_(2)NiSe_(4)/BWC as positive electrode and activated butterfly wings carbon as negative electrode acquires a high energy density of 42.9 Wh·kg^(-1)at a power density of 800 W·kg^(-1)with robust stability of 94.6%capacitance retention at 10 A·g^(-1)after 5,000 cycles.Moreover,the Z-Co_(2)NiSe_(4)/BWC as anode for sodium-ion batteries exhibits a high specific capacity of 568 mAh·g^(-1)at 0.1 A·g^(-1)and high cycling stability(maintaining 80.1%of the second cycle after 100 cycles).The outstanding electrochemical performances are ascribed to that the synergistic effect of bimetallic selenides and N-doped carbon improves electrochemical activities and conductivity.One-dimensional(1D)nanoneedles grown on 3D porous framework increase the exposure of redox-active sites,endow adequate transmission channels of electrons/ions,and guarantee stability of the electrode during charge/discharge processes.This study will shed light on the avenue towards extending such nanohybrids to excellent energy storage applications.