Ion Exchange of Layer Structured Crystal K_xTi_2-xFe_xO₄ (x = 0.80) and its Application as Cathode Material in a Rechargeable Lithium Battery

The layer structured titanate KxTi2-xFexO4 (x = 0.80) with the lepidocrocite (-FeOOH) type structure has been prepared in a solid state reaction using K2CO3, anatase type TiO2 and -Fe2O3 at 1373 K. Ion exchange reactions of K+ in the interlayer space were studied in aqueouse solutions. The host layers of the titanate were maintained on the ion exchange reactions and the resulting products were found to contain interlayer water. The interlayer water in the hydrogen ion exchange product was removed by heating at 383 K in a vacuum. The resulting titanate H0.79K0.01Ti1.20Fe0.80O4 was evaluated for its use as the cathode in a rechargeable lithium battery. The cathode exhibited discharge and charge capacities of 107 and 69 mAh/g for the first cycle in the voltage range of 1.5 - 4.2 V.