Preparation And Performance Research Of Black Phosphorus Based Anode Materials For Sodium Ion Battery

In recent years,rechargeable lithium-ion batteries(LIBs)have the advantages of high energy density,long cycle life and less pollution,and occupy a dominant position in the energy storage systems of portable electronic devices(laptops,mobile phones)and electric vehicles.However,it can be expected that the large-scale application of LIBs in the foreseeable future will be inhibited owing to the shortage and high prices of lithium resources.Therefore,sodium-ion batteries(SIBs)have been considered as a promising alternative to LIBs due to the natural abundance and low price of sodium resources.Although SIBs have similar working principles to LIBs,since the ion radius of sodium ion(1.02 (?))is larger than that of lithium ion(0.76 (?)),the SIBs have more sluggish electrochemical reaction kinetics process and lower energy density.In order to obtain commercial sodium ion batteries,it is necessary to develop high-performance sodium ion battery anode materials.Black phosphorus(BP)has been recognized as a prospective candidate anode material for Sodium-ion batteries(SIBs)due to its ultrahigh theoretical capacity of 2596 mAh/g and high electric conductivity(≈300 S/m).However,its large volume expansion and contraction during sodiation/desodiation lead to poor cycle stability.Black phosphorus powders are modified by ball milling with nitrogen-doped carbon nanotubes,and nitrogen-doped carbon nanotubes are coated on the surface to form a conductive network.The electrochemical performance of the modified black phosphorus material has been significantly improved.The second discharge capacity of BP/CNTs electrodes was about 1728 mAh/g,and it reached 1697 mAh/g after 100 cycles at a current density of 0.2 C,delivering a capacity retention of 98.2% compared to the first cycleIn this work,BP/Graphite nanoparticles/Nitrogen-doped multi-walled carbon nanotubes(BP/G/CNTs)composite with dual-carbon conductive network is successfully fabricated as a promising anode material for SIBs through a simple twostep mechanically milling process.The unique structure can mitigate the effect of volume changes and provide more electron conduction pathways during cycles.Furthermore,the formation of P-O-C bonds helps maintain the intimate connection between P and C,improving the cycling and rate performance.As a result,the BP/G/CNTs composite delivers a high initial Coulombic efficiency(89.6%)and high specific capacity for SIBs(1791 mAh/g after 100 cycles at 0.2 C,1665 mAh/g after100 cycles at 0.5 C).