Redox-Active Functionalized Graphene Nanoribbons As Electrode Material for Li-Ion Batteries

Current Li-ion systems still require substantial optimization in terms of realizing a more favorable price-to-performance ratio, especially in the renewable energy storage sector. To achieve this, several new materials and approaches are currently being tested and developed and, in particular, great promises and expectations lie in the graphene-based materials. Graphene is a stable 2D honeycomb-structured carbon material with extraordinary mechanical, optical, thermal and electrical properties.¹ On the other hand redox-active organic materials offer high theoretical capacities; however, most organic materials show drastic capacity fading during cycling, mainly caused by the dissolution of the active materials in organic electrolytes. In this work, we combined extraordinary properties of graphene with high capacity of organic compounds to get electrochemically stable composite material.  Graphene nanoribbons (GNRs) were grafted with electroactive molecules, where functionalized GNRs serve as a current collector, binder, and active material at the same time. GNRs were prepared by unzipping commercially available multi-walled carbon nanotubes with a Na/K alloy and in-situ functionalized with different hydroquinone derivatives. All synthesized materials were electrochemically characterized in Li-ion battery cells. The physical characteristics of the synthesized materials were determined by using evolved-gas analysis, Raman spectroscopy, and scanning electron microscopy. These analyses show the successful functionalization of GNRs and improved electrochemical performance compared to non-functionalized GNRs.²

(1) Rao, C.; Sood, A. Graphene: Synthesis, Properties, and Phenomena; Rao, C. N. R.; Sood, A. K., Eds.; 1st ed.; Wiley-VCH Verlag GmbH & Co. KGaA: Weinheim, 2013; p. 400.

(2) Pirnat, K.; Bitenc, J.; Jerman, I.; Dominko, R.; Genorio, B. Redox-Active Functionalized Graphene Nanoribbons as Electrode Material for Li-Ion Batteries. ChemElectroChem 2014, n/a–n/a.