Ultrathin δ-MnO2 nanosheets branched onto N-doped carbon nanotubes as binder-free cathode electrodes for aqueous zinc-ion batteries with a high areal capacity

Abstract

Manganese-based materials have been considered as promising electrode materials for aqueous zinc-ion batteries (ZIBs). However, the development of manganese-based materials is seriously restricted by their low electrical conductivity and sluggish reaction kinetics. In the present work, ultrathin birnessite-type δ-MnO 2 nanosheets branched onto N-doped carbon nanotubes grown on carbon cloth substrate (CC/NCNTs/δ-MnO 2 ) have been rational synthesized as a binder-free cathode electrode for aqueous ZIBs. The CC/NCNTs/δ-MnO 2 cathode possesses the desired merits including high electrical conductivity, large specific surface area, abundant active sites, fast ion diffusion, good structural stability and free of any polymer binders. When evaluated as a binder-free cathode electrode for aqueous ZIBs, the CC/NCNTs/δ-MnO 2 exhibits high areal capacity and energy density of 1.95 mAh cm −2 and 2.56 mWh cm −2 at a current density of 0.4 mA cm −2 , respectively, as well as decent rate capability and cycling stability. This work could provide an effective method to construct high-performance binder-free cathode electrodes for aqueous ZIBs. Ultrathin birnessite-type δ-MnO 2 nanosheets branched onto N-doped carbon nanotubes grown on carbon cloth substrate (CC/NCNTs/δ-MnO 2 ) have been rational synthesized, which exhibit excellent performance as binder-free cathode electrodes for aqueous zinc-ion batteries. • Ultrathin δ-MnO 2 nanosheets branched onto N-doped carbon nanotubes grown on carbon cloth are synthesized. • The CC/NCNTs/δ-MnO 2 is directly used as a binder-free cathode for aqueous zinc-ion batteries. • The CC/NCNTs/δ-MnO 2 possesses desired morphological, structural and compositional merits. • The CC/NCNTs/δ-MnO 2 exhibits a high areal capacity of 1.95 mAh cm –2 .