Novel Fe-compound incorporating porous carbon substrate promoting electrochemical performance of SiOx anodes for lithium-ion batteries

Abstract

Silicon oxide (SiO_x) shows great potential to be used in grid energy storage as the high-energy density anodes for lithium-ion batteries (LIBs) due to its low cost and high theoretical capacity. While the issues like low conductivity and volume expansion during cycles significantly decay the battery rate capability and cycle stability. To address the overall challenges, we effectively modified SiO_x hybrid structure by introducing metal incorporating porous carbon, derived from metal-organic frameworks (MOFs), denoted as Fe-C/SiO_x. The core-shell structure, coupled with the unique properties of both Fe-C and SiO_x components, offers a synergistic effect that effectively mitigates volume expansion and low conductivity problems, resulting in significant improvements in electrochemical performance. A discharge capacity of 658 mAh g⁻¹ at 100 mA g⁻¹ and an initial coulombic efficiency of 60 % are achieved. Additionally, it exhibits long-term cyclic stability with capacity of 650 mAh g⁻¹ after 300 cycles at 100 mA g⁻¹, and 337 mAh g⁻¹ after 500 cycles at 500 mA g⁻¹. The lithium ion storage mechanism investigation suggests conductive matrix of porous Fe-C primarily facilitates enhanced lithium-ion diffusion dynamics and offers pseudocapacitance to the electrode, which is crucial for practical battery applications where fast charging and discharging are required.