Reduced graphene oxide decorated with crystallized cobalt borate nanoparticles as an anode in lithium ion capacitors

(a) Schematic illustration of the preparation process of the Co-B/rGO composite, (b) Diagram of LIC full-cell based on Co-B/rGO anode. [Display omitted] •The crystallized Co-B/rGO composite was prepared via a facile in-situ grow method.•Co-B nanoparticles (5–20 nm) anchored on the surface of rGO nanosheets uniformly.•Co-B/rGO can facilitate the electrons transport and improve Li+ diffusion kinetics.•Co-B/rGO displays good electrochemical performance as an anode material in LICs. To improve the lithium storage properties of anode in lithium ion capacitors (LICs), reduced graphene oxide (rGO) decorated with crystallized cobalt borate nanoparticles (Co-B/rGO) was prepared by an in-situ growth method. Microstructural characterizations demonstrate that crystallized Co-B nanoparticles not only act as an effective electron transfer bridge between rGO nanosheets but also provide more active sites for lithium storage. As a result, LIC based on Co-B/rGO anode exhibited stable cycling performance with a capacitance retention of 75% after 2000 cycles at 2000 mA g−1, and high energy and power density. Thus, Co-B/rGO can be a promising anode material for LICs.