The use of methylcellulose for the synthesis of Li<inf>2</inf>FeSiO<inf>4</inf>/C composites

Abstract

The key parameters related to cathode materials for commercial use are a high specific capacity, good cycling stability, capacity retention at high current rates, as well as the simplicity of the synthesis process. This study presents a facile synthesis of a composite cathode material, Li2FeSiO4 with carbon, under extreme conditions: rapid heating, short dwell at 750 °C and subsequent quenching. The water-soluble polymer methylcellulose was used both as an excellent dispersing agent and a carbon source that pyrolytically degrades to carbon, thereby enabling the homogeneous deployment of the precursor compounds and the control of the Li2FeSiO4 particle growth from the earliest stage of processing. X-ray powder diffraction reveals the formation of Li2FeSiO4 nanocrystallites with a monoclinic structure in the P21/n space group (#14). The composite’s electrochemical performance as a cathode material in Li-ion batteries was examined. The influence of the amount of methylcellulose on the microstructural, morphological, conductive, and electrochemical properties of the obtained powders has been discussed. It has been shown that the overall electrochemical performance is improved with an increase of carbon content, through both the decrease of the mean particle diameter and the increase of electrical conductivity.