Silica derived from rice husk waste as anode material for lithium-ion battery: a comprehensive study

Abstract

This research investigates the synthesis and characterization of silica extracted from rice husks sourced from Adani in Enugu State, Nigeria, and its application in lithium-ion batteries. In this work, two methodologies for extracting SiO2 from rice husk were explored: rice husk pre-treatment process (acid leaching) and rice husk post-treatment process (alkaline digestion). The rice husks underwent acid leaching with 10 % HCl, followed by calcination at temperatures ranging from 500°C to 800°C. The sample post-treatment involved alkaline digestion using a 1 N sodium hydroxide solution. Results from structural analysis showed a progressive increase in purity and amorphous properties of silica up to a calcination temperature of 700°C. At 800°C, crystalline forms of silica, such as cristobalite and tridymite, were observed. The post-treated samples, especially those calcined at 700°C (PT700), exhibited comparative higher purity. Electrochemical studies were carried out using Cyclic Voltammetry (CV), Galvanostatic Charge/Discharge (GCD) and Electrochemical Impedance Spectroscopy (EIS), and the results show that the post treated rice husk that was calcined at 700 °C (PT700) had the highest specific capacity of 913 mAh g⁻¹ at a current density of 100 mA g−1 and retained ∼89 % of this capacity after 1000 charge-discharge cycles. The energy density of the PT700 sample was 302 Wh kg⁻¹, demonstrating its potential as a viable alternative to graphite in lithium-ion battery applications. The study concludes that silica extracted from rice husks is a sustainable and efficient material for use in energy storage devices, offering significant advantages in terms of reactivity, surface area, and electrochemical performance.