Impacts of morphology and N-doped carbon encapsulation on electrochemical properties of NiSe for lithium storage

Metal selenides are attractive anode materials for Li-ion batteries. However, poor structural stability and poor cycle performance limit the application of metal selenides. In this work, a solvent-directed self-assembly method is applied to prepare N-doped carbon-encapsulated nickel selenide (i.e., NiSe@N-doped carbon). Through simply adjusting the ratio of mixed solvent (H2O and ethanol) and coordination agent, NiSe-based anode with diverse morphologies including nanosheet-assembled multi-leaves NiSe, hierarchical porous flower NiSe@N-doped carbon, hexagonal plate NiSe@N-doped carbon, and multishell hollow sphere NiSe can be obtained after selenization. These anode materials possess distinct electrochemical performance owing to their different electrochemical kinetics, structural stability, and solid electrolyte interphase (SEI) growth. By introducing N-doped carbon encapsulation and constructing the well-defined hierarchical porous flower-like structure, the electrochemical performance is greatly enhanced, and moreover, the contents of SEI components (like NiF2, LixPOyFz, LiF, Li2CO3, etc.) can also be effectively reduced.