Facile synthesis of free-standing, flexible hard carbon anode for high-performance sodium ion batteries using graphene as a multi-functional binder

The use of reduced graphene oxide (rGO) as an environmentally friendly, multi-functional conductive binder is proposed as a novel strategy for manufacturing free-standing, flexible, high-performance hard carbon anodes for sodium ion batteries (NIBs). Compared with the conventional electrodes fabricated with insulating, fluorine-containing polymer binder (PVDF), the unique two-dimensional structure enable rGO can act as a strong binder and flexible backbone, resulting in free-standing, flexible hard carbon film, which can be directly used as anode for sodium ion batteries without any current collector. What's more, rGO also acts as active material, providing Na-storage capacity, as well as conductive addition to construct 3D conductive network, improving the rate performance of hard carbon. The obtained rGO-bonded hard carbon film with excellent flexibility can deliver a high reversible electrode capacity up to 372.4 mA h g(-1). After 200 charging/discharging cycles, the capacity loss is only 9%. The good electrochemical performance and excellent flexibility, combined with its facile fabrication approach make it to be a promising electrode candidate for developing next-generation flexible and environmentally friendly energy storage devices. (c) 2018 Elsevier Ltd. All rights reserved.