Ethanol reduced molybdenum trioxide for Li-ion capacitors

Orthorhombic molybdenum trioxide (α-MoO₃) is a layered oxide with promising performance as electrode material for Li-ion capacitors. In this study, we show that expansion of the interlayer spacing (by ~0.32 Å) of the structure along the b-axis, introduced by partial reduction of α-MoO₃ and formation of MoO_3-x (x=0.06~0.43), results in enhanced diffusion of Li ions. Freestanding hybrid electrodes made of MoO_3-x nanobelts and carbon nanotubes show excellent electrical conductivity. The combination of increased interlayer spacing and enhanced electron transport leads to high gravimetric and volumetric capacitances of about 420 F/g or F/cm³ and excellent cycle life of binder-free MoO_3-x electrodes.