Low cost nanostructured silicon for high performance li-ion battery anodes from rice husks

Abstract

Lithium ion technology is the most promising and is attracting a lot of attention due to its high energy density over other rechargeable teclmologies; however, there is need to improve the electrode materials so as to achieve the highest possible energy capacity. The general goal for battery development is to increase energy and power densities, while minimizing volumetric and mass constraints. Nano-Si has attracted considerable attention as a promising anode material in next generation Li-ion batteries for electric vehicles and portable electronics. This interest is primarily due to its large theoretical specific charge storage capacity of 4,200 mAh s'. which is more than ten times the theoretical capacity of conventional graphite anodes. While many guidelines for designing high-performance silicon anodes have been established, the existing methods for producing nano-Si anodes are still limited, complex, energy intensive and costly. Alternative fabrication methods that avoid the use of expensive processing are needed to produce Si anodes with comparable cost and scalability to graphite anodes. The recovery of useful materials from earth-abundant substances is of strategic importance for industrial processes. Pure Si nanoparticles (SiNPs) can be derived directly from rice husks, abundant agricultural byproduct. In this study new types of silicon nanoparticles will be extracted from rice husks by combustion, acid leaching and magnesiothermic reduction for rechargeable batteries. Silica content and the amount of metallic impurities in the samples will be estimated by X-Ray Fluorescence spectroscopic technique. Crystallinity will be probed by powder X-Ray Diffraction. The morphology and structure of Si nanopartic1es will be characterized using Transmission Electron Microscopy and Scanning Electron Microscopy respectively. Potentiostat and a Galvanostat will be used for battery testing. The study is specifically geared towards providing documented information on amounts of elemental silicon from rice husks varieties available in Kenya and its suitability for high performance Li-ion battery anodes.