Reduced graphene oxide decorated with SnO2 nanoparticles as negative electrode for lithium ion capacitors

The effort to increase the energy density of conventional electric double-layer capacitors (EDLCs) goes through the development of lithium-ion capacitors (LICs). Herein, we report a self-standing, binder-free composite as the battery-type negative electrode obtained by a low-cost and easily scalable method. Tin(IV) oxide nanoparticles (< 10 nm) embedded in a reduced graphene oxide matrix (SnO2-rGO) were prepared by an in-situ synthetic approach that involves the freeze/freeze-drying of a graphene oxide suspension in the presence of a tin precursor and its subsequent thermal reduction under argon atmosphere. Physicochemical and electrochemical characterization confirmed the optimum nanostructuration of the composite showing ultrafast response at high current densities. Its coupling with a highly porous olive pits waste-derived activated carbon (AC) as the capacitor-type positive electrode, enables the fabrication of a LIC with an excellent energy density output. The newly designed LIC is able to deliver 60Wh kg(-1) at 2.9 kW kg(-1) (t(discharge) approximate to 1 min) and still 27Wh kg(-1) at 10.6 kW kg(-1) (t(discharge) approximate to 10 s). (C) 2018 The Authors. Published by Elsevier Ltd.