Flexible solid state lithium batteries based on graphene inks

Abstract

Different formulations of solution-processable graphene have been characterised as electrode materials for use in electrochemical energy storage devices. Graphene was fabricated by chemical reduction of exfoliated graphene oxide (GO), and modified with either p-type (e.g. polyaniline) or n-type anionic groups (poly(styrenesulfonate) (PSS-) and poly[2,5-bis(3-sulfonatopropoxy)-1,4-ethynylphenylene-alt-1,4-ethynylphenylene] sodium salt (PPE-SO3-) anion). Solutions of these graphene compounds were deposited on charge collecting electrodes and used as battery cathodes. Electrodes using the anionically-modified graphene inks containing anatase titanate (TiO2) nanoparticles show improved performance over pristine graphene ink as well as the p-type conducting polymer modified ones. In addition, the open circuit voltage of batteries based on TiO2 has been boosted over 3 V with good cyclability when mixed with the graphene ink. Combined with a polymer electrolyte, this work suggests a feasible route towards fully printable rechargeable lithium batteries based on graphene inks. This approach is both versatile and scalable and is adaptable to a wide variety of applications.