Comparison of lithium//polyaniline secondary batteries with different dopants of HCl and lithium ionic salts

Polyanilines doped either with a protonic acid (HCl) or an electrolytic sol ution containing a lithium ionic salt (LiPF6 or LiBF4) are prepared and the ir electrochemical characteristics for use as polymer electrodes of lithium secondary batteries are investigated. An emeraldine base (EB) film doped w ith HCl has the highest d.c. conductivity(similar to 10 S/cm). An EB-LiPF6 film has higher conductivity (similar to 0.52 S/cm) than an EB-LiBF4 (simil ar to 0.082 S/cm) film. X-ray photoelectron spectroscopic analysis of the f ilms shows that some of the quinoid rings in EB are transformed into benzen iod rings through a doping process to generate polarons. The charge-dischar ge characteristics of lithium secondary batteries using the polyaniline fil ms as positive electrodes are determined. The cell using the EB-LiPF6 film and an electrolytic solution containing LiPF6 exhibits the highest specific discharge capacity(similar to 50 mA h/g), whereas the cell using EB-HCl an d LiPF6 solution has superior performance in the rapid saturation of discha rge capacity and in stability. (C) 2000 Elsevier Science S.A. All rights re served.