Intercalation pseudocapacitance is a promising ion storage mechanism that matches the energy density of traditional intercalation materials and the power density of capacitors. Niobium pentoxide, the first compound to be described as an “intercalation pseudocapacitor,” exhibits surface-limited electrochemical kinetics over a broad range of conditions despite intercalation via diffusion. Studies on nanostructured niobium pentoxide have been expansive however none have yet adjusted a single architectural parameter at a time while measuring the resulting performance. This comparison reduces model reliance and avoids the associated assumptions when determining nanostructure-property correlations. Here, a tailored isomorphic series of niobium pentoxide nanostructures with constant pore size and tuned wall thicknesses are examined. The dimensions of the niobium pentoxide architecture were found to predictably determine the sweep rate at which it transitions from surface-limited to diffusion-limited behavior. Additional experiments isolating the effects of electrolyte and film thickness unambiguously demonstrate solid-state diffusion of lithium as the dominant constraint in samples with 48.5-67.0 nm walls. These architectural dependencies revealed by this methodology is critical to enable energy-dense nanostructures that are custom designed to deliver specific power densities.

Tunable isomorphic architectures reveal the nanostructure dependence of Nb<sub>2</sub>O<sub>5</sub> intercalation pseudocapacitance

ACS Spring Meeting 2021

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Tunable isomorphic architectures reveal the nanostructure dependence of Nb2O5 intercalation pseudocapacitance

Tunable isomorphic architectures reveal the nanostructure dependence of Nb₂O₅ intercalation pseudocapacitance