One-dimensional Li_(3)VO_(4)/carbon fiber composites for enhanced electrochemical performance as an anode material for lithium-ion batteries

Lithium vanadium oxide(Li_(3)VO_(4))has gained attention as an alternative anode material because of its higher theoretical capacity(592 mAh g^(−1)),moderate ionic conductivity(∼10^(−4)S cm^(−1)),and lower working voltage range(∼0.5–1.0 V vs.Li/Li^(+))in comparison to other metal oxides.However,there are disadvantages to using Li_(3)VO_(4)as an anode material,such as low initial Coulombic efficiency and poor rate performance that is attributed to its low electronic conductivity(<10^(−1)0 S cm^(−1)).In the present study,the synthesis of one-dimensional Li_(3)VO_(4)electrode was performed via a facile method by using oxidized vapor grown carbon fiber as a template and the formation of the outer shells of conductive carbon via chemical vapor deposition technique.In a half-cell configuration,the prepared Li_(3)VO_(4)composites exhib-ited an enhanced electrochemical performance with a reversible capacity of 516.2 mAh g^(−1)after 100 cycles at a rate of 0.5 C within the voltage range of 0.01–3.0 V.At a high rate of 5 C,a large reversible capacity of 322.6 mAh g^(−1)was also observed after 500 cycles.The full cell(LVO/VGCF16-C||LiCoO_(2))using LiCoO_(2)as the cathode showed competitive electrochemical performance,which demonstrates its high potential in commercial applications.

One dimensional pea-shaped NiSe_(2) nanoparticles encapsulated in N-doped graphitic carbon fibers to boost redox reversibility in sodium-ion batteries

In recent years,sodium-ion batteries(SIBs)have emerged as a promising technology for energy storage systems(ESSs)because of the abundance and affordability of sodium.Recently,metal selenides have been studied as promising high-performance conversion-type anode materials in SIBs.Among them,nickel se-lenide(NiSe_(2))has received considerable attention due to its high theoretical capacity of 495 mAh g^(-1)and conductivity.However,it still suffers from poor cycling stability because of the low electrochemical reactivity,large volume expansion,and structural instability during cycles.To address these challenges,NiSe_(2)nanoparticles encapsulated in N-doped graphitic carbon fibers(NiSe_(2)@NGCF)were synthesized by using ZIF-8 as a template.NiSe_(2)@NGCF showed a high discharge capacity of 558.3 mAh g^(-1)with a fading rate of 0.14%per cycle after 200 cycles at 0.5 A g^(-1)in 0.01-3.0 V.At a very high current density of 5 A g^(-1),the capacity still displayed excellent long-term cycle life with a discharge capacity of 406.1 mAh g^(-1)with a fading rate of 0.016%per cycle after 3000 cycles.The mechanism of the excellent electrochem-ical performance of NiSe_(2)@NGCF was thoroughly investigated by ex-situ XRD,TEM,and SEM analyses.Furthermore,NiSe_(2)@NGCF//Na_(3)V_(2)(PO_(4))_(3)full-cell also delivered an excellent reversible capacity of 378.7 mAh g^(−1)at 0.1 A g^(−1)after 50 cycles,demonstrating its potential for practical application in SIBs.