Polymer coating of vanadium oxide nanowires to improve cathodic capacity in lithium batteries

Abstract

Vanadium oxide is a promising next generation cathode material in lithium-based batteries because of its high theoretical energy density. To address the shortcomings of V₂O₅, which include poor electrical conductivity and stability upon cycling, a core–shell structure consisting of high aspect ratio V₂O₅ nanowires coated with electroactive polyaniline (PANI) was synthesized. The two step solution-based process involved a facile hydrothermal synthesis of one dimensional V₂O₅ and subsequent in situ polymerization on the active material surface. Conformal coatings of PANI were achieved at a range of compositions (21–51% by weight) by altering the polymerization conditions. The composite nanowire structure was shown to benefit cycle stability, demonstrating a 90% improvement in discharge capacity over the uncoated wires after 40 cycles at increasing rates of charge. Improvements in rate capability were also correlated with increasing percentages of PANI in the composite, where the 51% PANI composite demonstrated a 57% increase in capacity over an uncoated sample at the high rate of 440 mA g⁻¹ (1 C). Here, we present evidence from galvanostatic cycling experiments that an electroactive polymer coating can enhance the underlying capacity of a cathode material.