Organic matter based battery materials have attracted large interest due to their inherent ability to provide an environmentally benign alternative to inorganic batteries because such materials can be produced from renewable resources via eco-efficient processes. One class or organic compounds that have been used as electrode materials or as component in composite materials in secondary batteries is conducting polymers. To be able to use conducting polymers in electrical energy storage applications the relatively rapid self-discharge (SD) needs to be overcome. We have therefore undertaken an investigation of the SD behavior of polypyrrole (PPy) in a PPy/cellulose composite material. In the present work we study the dependence of potential, temperature, and pH on the SD rate in oxidized PPy in water solution. Based on the results we present a model for SD in PPY where an initial and polymer intrinsic faradaic reaction leads to an unstable intermediate that reacts further to form various polymer degradation products (figure 1). From activation parameters we further estimate the redox potential of the intermediate state and conclude that SD is in fact the same process that leads to overoxidation, a general feature of p-doped conducting polymers. At elevated pH the faradaic SD reaction is out-competed by a potential independent reaction with a rate that depends linearly on hydroxide ion concentration.

Mechanisms of self-discharge in p-doped conducting polymers

249th National Meeting (2015)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.