Lithium-selenium (Li-Se) batteries suffer from the problems of polyselenides dissolution and volume expansion of active materials during the charge/discharge process. Moreover, the heavy atomic mass of selenium atoms limits the capacitive property of a Li-Se battery. Porous materials as the host for selenium particles reported by previous research studies are often disordered in pore structure and nonuniform in pore size. Herein, we report that a three-dimensional (3D) nitrogen-doped carbon photonic crystal (NCPC) with an ordered, interconnected structure was synthesized via a simple method to be the host of active materials. In addition, we prepared a Se-rich Se1-xSx by introducing a small amount of sulfur into a selenium ring to reduce the molecular mass but still keep the high electronic conductivity. As cathodes for a Li-Se battery, amorphous Se-rich Se1-xSx@NCPC composites exhibited high electrochemical performance with a specific capacity of 692 mA h g-1 at 0.1 Ag1-, an excellent rate capability of 526 mA h g-1 at 3 Ag1-, and an outstanding cycling property with an ultralow decay rate of 0.0132% per cycle at 0.6 Ag1- over 1000 cycles. Moreover, the pouch cell of Se1-xSx@NCPC composites also showed a good property with an energy of 253 Wh kg-1 at 0.1 Ag1- and an outstanding rate energy of 192 Wh kg-1 at 1.5 Ag1-, manifesting great potential in practical application.
Keywords: Se-rich composites; interconnected; lithium−selenium battery; ordered; photonic crystal; three-dimensional.