Conducting Polymers as Functional Binders for Lithium Ion Battery

Conducting polymers can be used as a functional binder material in lithium ion battery positive electrode. This work demonstrates the improvement in energy density and rate capability of LiFePO4 composite positive electrodes by replacing conventional binders with conducting polymers such as polyaniline (PANI), poly-o-methoxy aniline (POMA), poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS). Conducting polymers act in a dual role as binder and conducting additive in the positive composite electrode. The capacity and charging rate capability of the electrodes are improved by using PANI and POMA. However, due to their inherent lower conductivity in the emeraldine state, complete replacement of carbon additive is not possible. On the other hand in this work it is shown that PEDOT:PSS is stable and highly conducting in the working potential window of LiFePO4 electrodes (2.8-4 V). Hence composite electrodes free of any carbon additive are prepared with PEDOT:PSS and LiFePO4.