Polyaniline: Electrochemistry and application to rechargeable batteries

The present study shows that: (1) reversible electrochemical oxidation of the leuucoemeraldine base form of polyaniline in the pH range ≈1 to ≈4 occurs initially with no deprotonation to give the emeraldine salt; continued oxidation occurs with spontaneous deprotonation to give the pernigraniline base and (2) a rechargeable battery employing the analytically pure emeraldine base form of polyaniline as the cathode can be constructed. This battery shows very promising features such as a capacity of ≈148 Ah/kg, an energy density of ≈340 Wh/kg, coulombic recovery > 98%, good recyclability and satisfactory stand life.