Selenium element doping to improve initial irreversibility of C/SiOx anode in lithium-ion batteries

Abstract

To address the challenge of enhancing the initial Coulombic efficiency (ICE) of C/SiO_x anode in lithium-ion batteries (LIBs) and facilitating their widespread application, we developed porous C/SiO_x by carbonizing and activating rice husks with H₃PO₄ as activator. Subsequently, Se was introduced into the porous C/SiO_x and deposited both the surface and inner pore walls in order to produce Se@C/SiO_x through a solid-phase sublimation method. During the initial discharge process, Se contained within the porous C/SiO_x reacts with Li to form Li₂Se, which inhibits the formation of Li₂O and consequently reduces the thickness of the solid electrolyte interphase (SEI) film. This process facilitates easier diffusion of Li⁺ through SEI films, enhances ICE, as well as electrical and ionic conductivities, and improves rate performance. After introduction of Se, the ICE of porous C/SiO_x electrode rose from 57.02 % to 82.37 %. Additionally, the reversible capacity experienced an increase from 435 mAh/g to 844.4 mAh/g at a current density of 0.1 A/g. Even when subjected to a higher current density of 2.0 A/g, it was able to maintain a significant specific capacity of 574 mAh/g after undergoing 700 cycles.