Development of active materials for organic batteries based on electropolymerized polymers equipped with stable organic radicals

• Applicants: Dr. Christian Friebe; Dr. Stephan Kupfer
• Subject Area: Polymer Materials
• Term: since 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 441265816

Today's battery technology is mostly based on metals, such as lithium, lead, cobalt, or nickel. However, their limited natural occurrence as well as their toxicity and the resulting disposal problems limit their usability. Alternatively, polymeric compounds can be used. In this context, polymers based on stable organic radicals were studied intensively revealing promising charge-storage properties, in particular a superior redox reaction kinetic. However, such materials suffer from poor electrical conductivity, which limits the applicable charging/discharging rates, cancelling the advantageous electron-transfer characteristic. A promising approach to overcome this problem is the incorporation of conductive, i.e., conjugated, polymers. These materials offer several beneficial features that can be exploited for an organic battery: (i) As semiconductors, they offer electronical conductivity; (ii) they can be applied via electropolymerization, offering an efficient way to prepare insoluble polymeric structures directly on an electrode surface; and (iii) they themselves offer charge-storage capability. While the storage capability of conjugated polymers is often restricted due to a sloping charge / discharge voltage, the electronical conductivity as well as the electrochemical processability present highly advantageous features in combination with a stable redox moiety such as organic radicals. Based on recent results, the focus of the project lies on the improvement of the long-term stability and electronic conductivity of the built devices. This goal shall be realized by the variation of the involved molecular building blocks within a combined synthetic-computational approach. Consequently, an all-organic battery containing stable organic radicals and conjugated polymers prepared by means of electrochemical polymerization constitutes the final target.

• DFG Programme: Priority Programmes
• Subproject of: SPP 2248: Polymer-based batteries
• International Connection: United Kingdom
• Cooperation Partner: Professorin Dr. AnnMarie O' Donoghue