Magnesium-Ion Battery Anode from Polymer-Derived SiOC Nanobeads

Abstract

Tin-containing silicon oxycarbide (SiOC/Sn) nanobeads are synthesized with different carbon/tin content and tested as electrodes for magnesium-ion batteries. The synthesized ceramics are characterized by thermogravimetric-mass spectroscopy, Fourier-transform infrared spectroscopy, X-ray diffraction (XRD), Raman spectroscopy, N2 sorption analysis, scanning electron microscope, energy-dispersive X-ray, and elemental analysis. Galvanostatic cycling tests, rate performance tests, electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) tests, and ex situ XRD measurements are conducted. Results of battery performance tests present a high capacity of 198.2 mAh g−1 after the first discharging and a reversible capacity of 144.5 mAh g−1 after 100 cycles at 500 mA g−1. Excellent rate performance efficiency of 85.2% is achieved. Battery performances in this research are influenced by surface area, and tin contentof the SiOC/Sn nanobeads. EIS, CV tests, and ex situ XRD measurements reveal that higher surface area contributes to higher capacity by providing more accessible Mg2+ ion storage sites and higher rate capability by improving the diffusion process. Higher Sn content increases battery capacity through reversible Mg-Mg2Sn-Mg alloying/dealloying process and improves the rate performances by increasing electrical conductivity. Besides, SiOC advances cycling stability by preventing electrode collapse and enhances the capacity due to higher surface capacitive effects.