Design and fabrication of coal tar pitch-derived carbon coated bismuth-antimony sulfides for sodium storage performance

SUN Ying; FANG Yunke; MA Jiaxin; LIU Chang; WU Shuyao; YU Jiayi; QIU Jieshan; ZHANG Wei; MA Tianyi

doi:10.13226/j.issn.1006-6772.EE25042001

Abstract：Sodium-ion batteries(SIBs)are regarded as one of the most promising alternatives to lithium-ion batteries for next-generation energy storage.The development of anode materials with high specific capacity and superior cycling stability is critical to advancing the practical application of SIBs.Metal sulfides(e.g.,Bi2S3,Sb2S3)have emerged as competitive anode candidates for SIBs owing to their remarkable theoretical capacity and high energy density.To address the poor conductivity and significant volume expansion of metal sulfides during cycling,this work proposed a coal tar pitch-derived carbon-coating strategy.A Bi2S3/Sb2S3 composite was first synthesized via hydrothermal method,followed by coal tar pitch coating,high-temperature pyrolysis,and sulfurization,ultimately yielding a pitch-derived carbon-encapsulated Bi2S3/Sb2S3 nanocomposite(Bi2S3/Sb2S3@SNC).SEM,TEM,and XPS characterizations confirm that Bi2S3/Sb2S3@SNC possesses a three-dimensional continuous porous network structure,which provides shortened ion diffusion pathways and abundant sodium storage sites,thereby enhancing rate capability and capacity.Systematic electrochemical analyses characterized by LSV,EIS,and GITT reveal the influence of sulfide ratios on sodium storage kinetics.The optimized Bi2S3/Sb2S3@SNC-1(Bi∶Sb=1∶3)exhibits the lowest charge-transfer resistance and a high pseudocapacitive contribution of 96％,facilitating the formation of a stable solid-electrolyte interphase(SEI)and accelerated ion/electron transport.When evaluated as a SIB anode,Bi2S3/Sb2S3@SNC-1 delivers exceptional cycling stability of 494.4 mAh/g after 200 cycles at 0.2 A/g and rate performance of 419.6 mAh/g at 0.05 A/g and 282.0 mAh/g at 5 A/g,with 67.2％capacity retention.This work provides a novel strategy for designing high-performance metal sulfide anodes for SIBs.