Electrochemical performance of reduced graphene oxide/carbon nanotube hybrid papers as binder-free anodes for potassium-ion batteries

We investigated the electrochemical performance of reduced graphene oxide (rGO)/carbon nanotube (CNT) hybrid papers as binder-free anodes for potassium-ion batteries. RGO/CNT hybrid papers were fabricated by vacuum filtration and thermal reduction. The potassium-ion storage ability of rGO paper was significantly enhanced by CNT incorporation and the electrochemical performance of the hybrid papers was related to the weight ratio of CNTs. The optimal rGO/CNT-30% paper can deliver an initial reversible discharge capacity of 351 and 223 mA h g(-1) at a current density of 10 and 50 mA g(-1), respectively. A capacity of 148 mA h g(-1)was achieved after 200 cycles at a current density of 50 mA g(-1). The enhanced performance of rGO/CNT hybrid papers is attributed to the formation of a 3D conductive carbon network, in which the graphene layers are bridged by CNTs. Such a structure could effectively facilitate the transport of electrons and potassium ions and provide more storage sites for potassium ions.