Kagomé lattices as cathode: Effect of particle size and fluoride substitution on electrochemical lithium insertion in sodium- and ammonium Jarosites

摘要: Abstract Highly crystalline sodium and ammonium Jarosites, NaFe3(SO4)2(OH)6 NH4Fe3(SO4)2(OH)6, have been synthesized employing hydrothermal synthesis routes. The structures consist of anionic layers vertex-sharing FeO6 octahedra SO4 tetrahedral units with interlayer space occupied by Na ions, respectively. corner-sharing octahedral form six three rings similar to hexagonal tungsten bronze sheets also known as kagome lattice. These Jarosites are thermally stable up 400 °C undergo facile electrochemical lithium insertion through the reduction Fe3+ Fe2+. Galvanostatic charge–discharge indicates that 2.25 2 ions per formula unit can be inserted at an average voltage 2.49 2.26 V respectively, under slow discharge rate C/50. cycle-life experimental achievable capacity show strong dependence on particle sizes conditions. A small amount fluoride substitution improves both voltage.