Electrochemical Li Insertion into Conductive Polymer/  V 2 O 5 Nanocomposites

Abstract

Electrochemical insertion of Li into a series of "nanocomposites" comprised of alternating V,O, sheets and conductive polymer layers [polypyrrole (PPY) and polyaniline (PANI)] was examined and compared to the pristine V,O, material in terms of reversibility, Li site occupancy, and Li diffusion coefficients, and to the materials after oxidation treatment. The electrochemical characteristics are very sensitive to the nature of the polymer, its content, and location. The presence of surface polymer hinders Li insertion in these materials (by comparison to materials without surface polymer) and appears to result in the partial entrapment of Li ions. For modified [PANI],VV2O,, polymer incorporation results in better reversibility and increased Li capacity in the nanocomposite.[PPY]0,40V,O2 displays a greater first discharge capacity than the respective PANI material, but is not as cyclable as in O,-[PANI],,4V,O,. 0,-treatment results in the reformation of a high-potential Li site that is lost during the reductive intercalative polymerization. Li chemical diffusion coefficients are greater for the 0 2 -[PANI]V,20 nanocomposite than the xerogel by one order of magnitude, resulting in better performance at high current densities. Most important, the electrochemical response of these nanocomposites is greater than the sum of the two components (inorganic and organic), underlining the synergy of these hybrid materials.

Improvement of transport properties of Li x (Ni 0.8 Co 0.2 )O 2 oxide in the formation of Li x (Ni 0.8 Co 0.2 )O 2 /PANI composite

“…The improvement of the transport properties of the composite in comparison with those of the oxide is owing to the roll that plays the conducting polymer in the composite, i.e the conducting polymer trends to skirt the oxide particles interposing between them and forming an effective connecting chargetransfer-bridge on the surface. This is in completely concordance with the reports from literature where is described the roll that plays the conductive polymer in the enhancing of the lithium diffusivity of the composite [12]. This effect is particularly evidenced by the better reversibility of Li-insertion, during charge-discharge cycles in a battery prototype, for the composite than for that of the pristine oxide showed in Fig.…”

Recent advances in conjugated polymer energy storage

“…Overall, investigations of V 2 O 5 / PANI composites have demonstrated promise because the two components work together synergistically to improve coulombic efficiency and charge transport. 23,171,172,[175][176][177] Our work has shown that the capacity is optimized at a particular thickness, where thicker films are subject to ion diffusion limitations. 23 To address this issue, we are replacing conventionally synthesized PANI with PANI-NF to introduce a porous electrode morphology.…”

Graphene-modified nanostructured vanadium pentoxide hybrids with extraordinary electrochemical performance for Li-ion batteries

“…However, even for V 2 O 5 xerogel, the same challenges of low electrical conduction (both intraparticle, within a V 2 O 5 particle, and interparticle, between V 2 O 5 particles), slow lithium diffusion and structure stability/reversibility still remain. Efforts have been made to improve the conductivity by coating the V 2 O 5 xerogel with conductive materials (that is, single-wall carbon nanotubes) 17 , doping metals 18 and organic polymers [19][20][21][22][23] . These measures can improve the V 2 O 5 xerogel only to a certain degree, and none of them significantly improve the structural stability and reversibility.…”