ZIF-L derived carbon flower with in-situ grown CNTs accelerates the reaction kinetics of Li-Se batteries

Lithium-selenium (Li-Se) batteries have attracted increasing attention because of their excellent volumetric specific capacity. However, the sluggish electrochemical reaction kinetics in carbonate-based electrolyte and limited utilization of active material hinder its development. In this work, we report a ZIF-L derived carbon flower to be Se host, in which the hierarchically porous carbon effectively encapsulate Se species and alleviate the volume expansion, while the nanosheets-assembled conductive network provides shorter paths for mass transfer by confining charge/ion within a flat. Moreover, the interconnected framework exhibits strong capability in preventing mechanical aggregation and fragmentation of the 2D nanosheets. After modification with in-situ grown CNTs, superior capacitive contribution and cycling performance are achieved due to the further enhanced electrochemical reaction kinetics. As a result, Se/CNTs@HPC-5 cathode demonstrates a reversible specific capacity of 606 mAh g-1 after 350 cycles at 0.5 C, with only 0.013% capacity decay per cycle. When the current rises to 5 C, it can still provide a capacity of 355 mAh g-1. This work would shed some light on the future development of carbon material for high-performance Li-Se batteries.