(693e) Freestanding V2O5-PEDOT Thin Film Electrode for Rechargeable Aqueous K-Ion Energy Storage

Rechargeable aqueous
electrochemical energy storage (EES) devices are a promising technology for a
wide range of energy storage applications due to their low cost and superior
safety compared to Li-ion batteries. However, their low energy density has
inhibited implementation. Materials with layered structures possess favorable
characteristics for improving the energy density of aqueous EES devices. In
particular, for aqueous EES using cations with larger ionic radii (e.g. Na-ions
and K-ions), which are more abundant and therefore, more sustainable as well as
less expensive than Li-ions. Herein we report the exfoliation of bulk vanadium
pentoxide using the conductive polymer poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) via
a wet chemical method. The resulting exfoliated V₂O₅-PEDOT:PSS metal oxide-polymer composite can be fabricated
into freestanding thin film electrode with simple processing techniques. Structural
characterization of the exfoliated V₂O₅-PEDOT:PSS composite was investigated with various techniques
including synchrotron X-ray diffraction and neutron total scattering analyzed in
real space with the Atomic Pair Distribution Function. A structural rearrangement
from bulk vanadium pentoxide to a structure with large interlayer spacing and a
coherence length on the nanoscale is observed upon exfoliation. Cyclic
voltammetry measurements conducted in a 1M KCl
electrolyte and 1V potential window show multiple redox features, which remain visible
at all scan rates tested between 10 and 1000 mV/s. The exfoliated V₂O₅-PEDOT:PSS nanocomposite not only has the ability for high
capacity K-ion storage (605 F/g at 10 mV/s, or 168 mAh/g
100s discharge time) but also the ability to operate at fast charge-discharge
rates (203 F/g at 1 V/s, or 56 mAh/g at a 1s discharge
time). This work demonstrates a scalable top down approach for the development
of a freestanding, high capacity and high power nanocomposite electrode for
aqueous K-ion energy storage.