Nanostructure Dependence of T‐Nb2O5 Intercalation Pseudocapacitance Probed Using Tunable Isomorphic Architectures. (2nd November 2020)

• Record Type: Journal Article
• Authors: van den Bergh, Wessel; Lokupitiya, Hasala Nadeesini; Vest, Natalie Alicia; Reid, Barry; Guldin, Stefan; Stefik, Morgan
• Is Part Of: Advanced functional materials. Volume 31:Number 1(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2020-11-02
• Subjects: cyclic voltammetry -- kinetic control -- Li + intercalation -- pseudocapacitance -- soft templating; Materials -- Periodicals; Chemical vapor deposition -- Periodicals; 620.11
• DOI: 10.1002/adfm.202007826
• Languages: English
• ISSNs: 1616-301X

Abstract

Abstract: Intercalation pseudocapacitance has emerged as a promising energy storage mechanism that combines the energy density of intercalation materials with the power density of capacitors. Niobium pentoxide was the first material described as exhibiting intercalation pseudocapacitance. The electrochemical kinetics for charging/discharging this material are surface‐limited for a wide range of conditions despite intercalation via diffusion. Investigations of niobium pentoxide nanostructures are diverse and numerous; however, none have yet compared performance while adjusting a single architectural parameter at a time. Such a comparative approach reduces the reliance on models and the associated assumptions when seeking nanostructure–property relationships. Here, a tailored isomorphic series of niobium pentoxide nanostructures with constant pore size and precision tailored wall thickness is examined. The sweep rate at which niobium pentoxide transitions from being surface‐limited to being diffusion‐limited is shown to depend sensitively upon the nanoscale dimensions of the niobium pentoxide architecture. Subsequent experiments probing the independent effects of electrolyte concentration and film thickness unambiguously identify solid‐state lithium diffusion as the dominant diffusion constraint even in samples with just 48.5–67.0 nm thick walls. The resulting architectural dependencies from this type of investigation are critical to enable energy‐dense nanostructures that are tailored to deliver a specific power density. Abstract : Persistent micelle templates are used to prepare a series of nanoscale T‐Nb2 O5 architectures that vary a single spatial variable at a time in order to establish unambiguous nanostructure–property relationships. The departure from intercalation pseudocapacitance behavior (surface‐limited kinetics) depend sensitively upon the intercalation length scale. Such nanostructure‐performance dependencies are critical to enable architectures that are "nano‐optimized" to specific needs.