Carbon-layer-coated porous Ni-doped CoSe 2 (Ni-CoSe 2 /C) nanospheresh ave been fabricatedb yafacile hydrothermal methodf ollowed by an ew selenization strategy. The porouss tructure of Ni-CoSe 2 /C is formed by the aggregation of many small particles (20-40 nm), whicha re not tightly packed together,b ut are interspersed with gaps. Moreover,t he surfaces of these small particles are covered with at hin carbon layer.N i-CoSe 2 /C delivers superior rate performance (314.0 mA hg À1 at 20 Ag À1), ultra-longc ycle life (316.1 mA hg À1 at 10 Ag À1 after 8000cycles), and excellent full-cell performance (208.3 mA hg À1 at 0.5 Ag À1 after 70 cycles)w hen used as an anode material for half/full sodium-ion batteries. The Na storage mechanism and kinetics have been confirmed by ex situ X-ray diffraction analysis, assessment of capacitance performance, and ag alvanostatic intermittent titrationt echnique (GITT). GITT shows that Na + diffusion in the electrode material is ad ynamic changep rocess, which is associated with ap haset ransitiond uring chargea nd discharge. The excellent electrochemical performance suggestst hat the porous Ni-CoSe 2 /C nanospheres have great potential to serve as an electrode materialf or sodium-ion batteries.

Octahedral NiSe2 was fabricated by a facile hydrothermal method. It showed excellent Na ion storage performance when used as an anode material for sodium-ion batteries.

Two-dimensional fence-like Co-doped NiSe2/C (Co-NiSe2/C) nanosheets are synthesized though using facile solvothermal method and selenization process. Co-NiSe2/C nanosheets are composed of interlaced nanorods, which are made up of nanoparticles with...