Sulfonated polyaniline films as cation insertion electrodes for battery applications. Part 1.—Structural and electrochemical characterization

Abstract

Sulfonated polyaniline (SPAN) was synthesized by sulfonation of polyaniline (PANI) base with fuming sulfuric acid. Thin films were cast from polymer solutions in basic media. The polymer films were characterized by X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR) spectroscopy, ultraviolet-visible-near-infrared spectroscopy, scanning electron microscopy (SEM) and cyclic voltammetry. XPS in combination with FTIR showed that the preparation procedure led to ca. 47% sulfonation of an otherwise unchanged polyaniline backbone. The NIR spectra of SPAN films showed a polaron band at higher energies than with polyaniline. This is in agreement with the lower conductivity of SPAN as compared with polyaniline. SEM micrographs of the SPAN films showed a compact globular morphology. Electrodes modified with thin SPAN films exhibited two redox steps, both in aqueous and in non-aqueous electrolytes. The specific charge stored in SPAN films was found to be ca. 37 A h kg-' in aqueous solution (only the first redox step) and ca. 68 A h kg-' in non-aqueous media (both redox steps). A practical SPAN-Li battery could have 50% more specific energy than a PANI-Li battery. The optical spectra of SPAN films exhibited bands at 310, 450 and 750 nm, the intensities of which changed during the redox process. The absorption coefficients of SPAN (emeraldine base state) solutions had values of a = 41 0 at 31 3 nm and a = 239 at 563 nm. The suitability of SPAN for use as a cation-insertion material for battery and electrochromic applications is discussed.

Covalent attachment of functional side-groups to polyaniline nanofibres

“…At low pH values, a polaron band appears at 450 nm with a tail above 600 nm (Barbero et al, 1994). When PAni fibres are exposed to a higher pH environment these bands disappear, and a π-π* transition band at 341 nm dominates due to dedoping.…”

Synthesis and characterisation of controllably functionalised polyaniline nanofibres

“…In a low pH environment, a characteristic PAni band appears at 412nm and represents the doped state. The tail above 600nm can be attributed to a polaron transition [41] . These bands are also observed for the functionalised 45 material (22mg and 44mg MA).…”

Spectroscopic, morphological and electrochromic characterization of layer-by-layer hybrid films of polyaniline and hexaniobate nanoscrolls

“…In this way, polyaniline deserves to be highlighted since it shows significant application in electronic devices such as electrochromic devices, 26-28 sensors 29-32 and batteries. [33][34][35] PANI is quite easily processable, low cost and shows environmental stability. 10 The emeraldine base form of polyaniline (PANI-EB) is equally constituted by reduced and oxidized segments (Scheme 2).…”