Super Na+ Half/Full Batteries and Ultrafast Na+ Diffusion Kinetics of Cobalt-Nickel Selenide from Assembling Co0.5Ni0.5Se2@NC Nanosheets into Cross-Stacked Architecture

Main observation and conclusion Exploration of advanced anode materials for sodium-ion batteries (SIBs) is still a big challenge due to the large radius of sodium. In this work, the hierarchical architectures assembled from N-doped carbon-coated Co0.5Ni0.5Se2 (Co0.5Ni0.5Se2@NC) nanoparticles encapsulated into cross-stacked nanosheets have been successfully prepared from the cobalt-nickel binary-metal organic frameworks (CoNi-MOF) by two steps of the solid-state selenization and carbon coating processes. Importantly, the resultant hierarchical Co0.5Ni0.5Se2@NC architecture can achieve a satisfactory electrochemical performance, maintaining a high-rate capacity of 330 mA center dot h center dot g(-1) at 3 A center dot g(-1) and a stable cyclability of 100 cycles without obvious capacity decay at 0.2 A center dot g(-1). The design of distinct superstructure can not only be applied to other electrode materials but also boost the forward development of energy storage systems.