Organic Battery Materials based on Conducting Polymer Backbones with High Capacity Pending Groups
2014 (English)Conference paper, Abstract (Refereed)
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. The development of organic battery materials rely on several key factors that need to be resolved, the most important being dissolution problems, limited electronic conductivity, degradation of active material and slow redox kinetics. Conducting polymers are insoluble in most electrolytes, they are electronically conducting and show fast redox conversion but are, to some extent, unstable and have insufficient charge capacities for battery applications.
To understand the instability of conducting polymers we have measured self discharge rates in polypyrrole at different temperatures. From these experiments it is clear that the self-discharge originates from an activated redox reaction with an activation barrier of around 0.4 eV. Although the exact nature of the redox reaction has not been identified we have been able to link the self discharge to, what is commonly referred to as, over-oxidation. Over-oxidation is common to polyacetylene, polyparaphenylene, polypyrrole and polythiophene and this mechanism of self discharge is thus a general feature of conducting polymers. This self-discharge mechanism is suppressed by low polymer doping levels, low potentials and low temperatures.
By attaching high capacity redox active groups onto the conducting polymer backbone the charge capacity can be increased while retaining electronic conductivity and insolubility. We have attached quinone groups to each repeat unit of polypyrrole for this purpose. Interestingly, in-situ spectroscopic measurements show that during quinone redox conversion the polymer doping level is in-fact reduced. Since the doping level of the polymer affects the rate of self-discharge the attachment of quinone units to the polypyrrole chain not only increases the charge capacity but also provides a conceptual strategy to control self discharge.
Place, publisher, year, edition, pages
2014. Vol. 247
Physical Chemistry Engineering and Technology
Research subject Engineering Science with specialization in Nanotechnology and Functional Materials
IdentifiersURN: urn:nbn:se:uu:diva-232675ISI: 000348457600168OAI: oai:DiVA.org:uu-232675DiVA: diva2:748982
247th ACS National Meeting & Exposition, Chemistry & Materials for Energy, March 16-20, 2014, Dallas, Texas
Meeting Abstract: 434-ENFL2014-09-222014-09-222015-03-23Bibliographically approved