High-rate lithium intercalation into composite electrodes of crystalline β-FeOOH and carbon powder

Composite electrode material of crystalline beta-FeOOH with a (2 x 2) tunnel-type structure and carbon was prepared by hydrolyzing of 0.1 mol dm(-3) FeCl3 aqueous solution in which carbon powder was dispersed. The composite electrode material of fine beta-FeOOH particles and Ketjen black (KB: specific surface area 1270 m(2) g(-1)), of high specific surface area exhibited the high capacity of more than 250 mAh g(-1) per beta-FeOOH weight and good cycle performance at rapid charge-discharge current density of 5.0 mA cm(-2) (4.5 A g(-1) per beta-FeOOH weight) in nonaqueous electrolytes including lithium ions. Composite electrode with KB powder exhibited high capacities compared to that with acetylene black (AB) powder. Composite electrode materials of crystalline beta-FeOOH and carbon are one of the promising candidates as electrode materials for energy storage devices such as hybrid capacitors that high-power operations are required.