Efficient Transport Networks in a Dual Electron/Lithium-Conducting Polymeric Composite for Electrochemical Applications

• Published in: ACS applied materials & interfaces 2018-05, Vol.10 (18), p.15681-15690
• Main Authors: McDonald, Michael B, Hammond, Paula T
• Format: Article
• Language: English
• ISSN: 1944-8244; 1944-8252
• DOI: 10.1021/acsami.8b01519

In this work, an all-functional polymer material composed of the electrically conductive poly­(3,4-ethylenedioxythiophene):poly­(4-styrenesulfonic acid) (PEDOT:PSS) and lithium-conducting poly­(ethylene oxide) (PEO) was developed to form a dual conductor for three-dimensional electrodes in electrochemical applications. The composite exhibits enhanced ionic conductivity (∼10–4 S cm–1) and, counterintuitively, electronic conductivity (∼45 S cm–1) with increasing PEO proportion, optimal at a monomer ratio of 20:1 PEO:PEDOT. Microscopy reveals a unique morphology, where PSS interacts favorably with PEO, destabilizing PEDOT to associate into highly branched, interconnected networks that allow for more efficient electronic transport despite relatively low concentrations. Thermal and X-ray techniques affirm that the PSS–PEO domain suppresses crystallinity, explaining the high ionic conductivity. Electrochemical experiments in lithium cell environments indicate stability as a function of cycling and improved overpotential due to dual transport characteristics despite known issues with both individual components.