Preparation and electrochemical lithium storage performance of porous silicon microsphere composite with metal modification and carbon coating

金属改性与碳包覆的多孔硅微球复合材料的制备及其电化学储锂性能

This work adopts a multi⁃step etching⁃heat treatment strategy to prepare porous silicon microsphere com⁃posite with Sb⁃Sn surface modification and carbon coating(pSi/Sb⁃Sn@C),using industrial grade SiAl alloy micro⁃spheres as a precursor.pSi/Sb⁃Sn@C had a 3D structure with bimetallic(Sb⁃Sn)modified porous silicon micro⁃spheres(pSi/Sb⁃Sn)as the core and carbon coating as the shell.Carbon shells can improve the electronic conductivi⁃ty and mechanical stability of porous silicon microspheres,which is beneficial for obtaining a stable solid electrolyte interface(SEI)film.The 3D porous core promotes the diffusion of lithium ions,increases the intercalation/delithia⁃tion active sites,and buffers the volume expansion during the intercalation process.The introduction of active met⁃als(Sb⁃Sn)can improve the conductivity of the composite and contribute to a certain amount of lithium storage ca⁃pacity.Due to its unique composition and microstructure,pSi/Sb⁃Sn@C showed a reversible capacity of 1247.4 mAh·g^(-1) after 300 charge/discharge cycles at a current density of 1.0 A·g^(-1),demonstrating excellent rate lithium storage performance and enhanced electrochemical cycling stability.

以工业级SiAl合金微球为前驱物,采用多步刻蚀-热处理策略,制备了金属(Sb⁃Sn)改性与碳包覆的多孔硅微球复合材料(pSi/Sb⁃Sn@C)。pSi/Sb⁃Sn@C具有以Sb⁃Sn改性的多孔硅微球(pSi/Sb⁃Sn)为核、碳包覆层为壳的三维结构。碳外壳可以提高多孔硅微球的电子导电性和机械稳定性,有利于获得稳定的固体电解质界面(SEI)膜;而三维多孔核可以促进锂离子的扩散,增加嵌/脱锂活性位,缓冲嵌锂过程中的体积膨胀。此外,活性金属(Sb⁃Sn)的引入能够提高复合材料的导电性,并可以贡献一定的储锂容量。由于其特殊的组成和独特的微观结构,pSi/Sb⁃Sn@C复合材料在1.0 A·g^(-1)电流密度下充放电300次后的可逆容量为1247.4 mAh·g^(-1),显示了良好的高速率储锂性能和优异的电化学嵌/脱锂循环稳定性。