Fabricating and Probing Forsterite Li-ion Battery Anode Electrodes

Abstract

In an effort to minimize irreversible capacity loss and volume expansion, research on Si nanocomposite materials with a SiO<sub>x</sub>/Mg<sub>2</sub>SiO<sub>4</sub>/SiO<sub>x</sub> structure through a magnesiothermic reduction process (MTR) has attracted much attention from researchers. Mg<sub>2</sub>SiO<sub>4</sub>(forsterite) has been shown to improve the initial coulombic efficiency (ICE) by minimizing the irreversible capacity loss due to pulverization and highvolume expansion of the Si-based anode complexes. In this study, forsterite was synthesized as the main phase by Mg vapor control in the MTR process. We used an electrophoretic deposition system to investigate the intrinsic electrochemical properties of forsterite, which served as a buffer for the improvement of ICE, associated with the lithiation/delithiation process. Importantly, a stable specific capacity of up to 200 mAh/g was achieved during the charging/discharging process, demonstrating its potential use as an anode electrode. We also found that no significant capacity was found by alloying with Si. In other words, there is a lithium storage mechanism unique to forsterite which is not related to the Si alloying reaction in the storage mechanism. The results presented here are the first demonstration of a forsterite lithium-ion battery; forsterite has only been considered as a buffer layer of the Si/SiO composite structure. Furthermore, the finding is of crucial importance as it provides the basis for various approaches to develop reversible and high power li-ion battery anodes by synthesizing the Si composite through MTR.