Polyaniline Electrode Activation in Li Cells

Abstract

Polyaniline (PANi) can be used as an electroactive organic cathode material in Li-cells with multiple redox states. The theoretical specific capacity of the emeraldine base (PEB) is 150 mAh g−1. In this study, we show how the specific capacity of PEB90−xCBxPVDF10 cathodes is dependent upon the mass percentage of PEB and carbon black (CB) in the potential range of 2.0–4.0 V. The capacity of PEB90−xCBxPVDF10 cathodes is initially very low, steadily increasing during initial cycling. A constant capacity is eventually reached with continued cycling. Microscopic imaging and elemental analysis of cycled electrodes reveals how the electrode composition and morphology of PEB90−xCBxPVDF10 cathodes plays an integral role in the magnitude of the specific capacity during the initial and steady state cycles. We propose a diffusion-limited model as an attempt to elucidate the differences in the total specific capacity among PEB90−xCBxPVDF10 cathodes. From our findings, we propose that increasing CB content provides more ion-diffusion channels throughout the PEB90−xCBxPVDF10 cathodes. This model is consistent with our findings in that more CB content reduces the amount of cycles required to reach steady state cycling and increases the magnitude of the specific capacity at steady state.