The charge/discharge mechanism of polyaniline films doped with LiBF4 as a polymer electrode in a Li secondary battery

The electrical conductivity of polyaniline films doped with 1 M LiBF4 is si milar to0.082 S/cm. The discharge capacity is increased with cycling and th en saturates at more than 15 cycles. We obtained a saturated discharge capa city of about similar to 40 mAh/g, which is only about 38% of the theoretic al capacity. The solution conductivity is continuously decreased as the Li salt concentration is reduced. The Li salt concentration in the electrolyte and the concentration of Li salt as a doping agent affects the charge/disc harge reaction. By the analysis of de conductivity, XPS, and ESR data, the charging mechanism is explained by a charge separation mechanism which depe nds on the concentration of ionic salt in the electrolyte. (C) 2000 Elsevie r Science B.V. All rights reserved.