A novel spitball-like Co3(NO3)2(OH)4@Zr-MOF@RGO anode material for sodium-ion storage

Metal-organic frameworks (MOFs) with 3D structure and tunable composition can provide more electrochemical active sites for redox reactions. They are expected to achieve stable cycles for reversible sodium ion storage. In this work, a novel spitball-like anode material for sodium-ion batteries (SIBs) has been prepared by a facile solvothermal method followed by the spray drying, in which the reduced graphene oxide (RGO) is coated on the composite of cobalt hydroxidenitrate (Co-3(NO3)(2)(OH)(4)) combined with the zircomiun based MOFs (Zr-MOF). The combination of Co-3(NO3)(2)(OH)(4) with Zr-MOF can not only improve the structural stability but also enlarge the specific surface area of anode materials. Meanwhile, the coating of spitball RGO can further improve the electric conductivity and the cycling stability of Co-3(NO3)(2)(OH)(4)@Zr-MOF composite effectively. As a result, such a composite anode can exhibit a high reversible capacity of 555 mAh g(-1) at 0.1 A g(-1) as well as a capacity retention ratio of 94.3% with discharge capacity of 525 mAh g(-1) after 100 cycles. Notably, the Co-3(NO3)(2)(OH)(4)@Zr-MOF@RGO anode can also deliver a high-rate capacity of 340 mAh g(-1) at 1 A g(-1). These results suggest that the Co-3(NO3)(2)(OH)(4)@Zr-MOF@RGO material is a promising anode to build the high-rate and long-life SIBs. (C) 2020 Elsevier B.V. All rights reserved.