Application of quaternized activated carbon derived from Macadamia nutshells for the removal of hexavalent chromium from aqueous solutions

Abstract

Over the years, new synthesis routes of the cathode electrochemical active material for lithium-ion batteries have improved remarkably to optimize their capacity and cycle life performance.This review study focused on the use of some techniques to synthesize the common cathode materials (LiCoO 2 , LiMn 2 O 4 ,LiFePO 4 ).The most common and simplest synthesis method was the mixing of powders in their solid-state form and heating them at relatively high temperatures over long periods.Other methods included the formation of sol-gel products that could be either heat-treated more or could be used directly by means of a spray pyrolysis method producing the desired active material.The spray pyrolysis method showed that suitable cathode oxide materials formed in shorter periods, resulting in small homogenous particles with narrow particle size distribution.The spray pyrolysis method allowed for making doped or coated cathode materials easily of the various base forms LiCoO 2 , LiMn 2 O 4 and LiFePO 4 , with doping elements such as Zr, Mn, Ni, Co, B or Mg.Coating of the particles could also be done with materials such as glassy lithium boride oxide, TiO 2 or carbon.These additives to the cathode material improved the active material's physical morphology and electrochemical properties.