Improved Initial Coulombic Efficiency of Optimized SiOx Via Simple Magnesiothermic Reduction As High-Performance Anode Material for Lithium-Ion Battery

Abstract

With the increasing demands of portable electronics and electric vehicles, rechargeable lithium-ion batteries are strongly considered from the utility standpoint due to their high energy density. Lithium-ion batteries have become a leading technology [1]. Silicon-based materials have gained tremendous attention due to their great importance in various techniques such as electronic devices, solar energy conversion and high capacity anode for LIBs [2]. Low cost, high energy density, SiO considered one of the most promising anode material for lithium-ion batteries. However low initial Coulombic efficiency is a serious limitation for the practical application of SiO. The intrinsic low Coulombic efficiency (ICE) caused by the side reactions between Li-ions and Si as well as the formation of Solid Electrolyte interphase (SEI) [3].Many methods have been approached to solve this challenge, pre-lithiation, metal reduction, graphene coating, Nano-sizing, nanotubes, and fabrication of silicon and carbon composite. Among these methods, the metallothermic reduction has gained significant attention. The reducing metal should be inexpensive, convenient to handle and easily removable by-product, therefore Mg has been widely used metal to reduce Si oxides [4].Herein, we report an affordable low temperature and low-cost synthesis method to synthesize SiOx by partial reduction of SiO via Magnesiothermic reduction. To find out the optimum amount of Mg to reduce SiO, various amount of Mg has been investigated. The ICE was gradually increased with the amount of Mg increased. The electrochemical performance was tested by cyclic voltammetry (CV) and discharge-charge measurement. The results show the sample prepared at 85% (mole) of Mg exhibited the larger storage capacity of 1656.47 mAh g-1 and outstanding high initial Coulombic efficiency of 83.09%, and better cyclic property as compare to Bare SiO.[1] M. Armand and J.-M. Tarascon, “Building better batteries,” Nature, vol. 451, p. 652, Feb. 2008.[2] N. Lin et al., “A low temperature molten salt process for aluminothermic reduction of silicon oxides to crystalline Si for Li-ion batteries,” Energy Environ. Sci., vol. 8, no. 11, pp. 3187–3191, 2015.[3] Y. Zhang et al., “An affordable manufacturing method to boost the initial Coulombic efficiency of disproportionated SiO lithium-ion battery anodes,” J. Power Sources, vol. 426, pp. 116–123, 2019.[4] Y. Lai, J. R. Thompson, and M. Dasog, “Metallothermic Reduction of Silica Nanoparticles to Porous Silicon for Drug Delivery Using New and Existing Reductants,” Chem. Eur. J., vol. 24, no. 31, pp. 7913–7920, 2018.