A Dual Electronic/Li Ion Conducting Polymer Blend for the Lithium Ion Battery Electrode Matrix

Presenter: 

Michael B. McDonald

Authors: 

Michael B. McDonald and Paula T. Hammond

Author Affiliation: 

Massachusetts Institute of Technology

Abstract: 

The storage materials used in conventional lithium ion batteries are contained in mixtures of materials to enhance charge transport and support the materials structurally, including carbon black and polymers. These 'cast slurries' lack a continuously conductive structure for both electrons and lithium ions to pass freely, and so a new material is proposed herein that forms continuous pathways for both ions and electrons using a mixture of intrinsically conductive polymer materials: poly-3,4-ethylenedioxythiophene-poly(4-styrenesulfonate) (PEDOT:PSS) and poly(ethylene oxide) (PEO). Solutions containing varying ratios and molecular weights were drop-cast and found to have enhanced electrical conductivity with increasing PEO (the electrically insulating polymer). Using X-ray diffraction, differential scanning calorimetry, and atomic force microscopy, insights into the microstructure of the blend are found, noting an alignment of the PEDOT phase via the addition of PEO. By combining the blends with storage material in lithium ion cells under galvanostatic charging/discharging, it is found that the blends are potentially suitable for electrode support materials in batteries as an alternative to conventional materials.