In situ formed carbon bonded and encapsulated selenium composites for Li–Se and Na–Se batteries

As high capacity cathodes for Li-ion and Na-ion batteries, carbon bonded and encapsulated selenium composites (C/Se) with a high loading content of 54% Se were synthesized by the in situ carbonization of a mixture of perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA) and selenium (Se) in a sealed vacuum glass tube. Because Se is physically encapsulated and chemically bonded by carbon, the shuttle reaction of polyselenide is effectively mitigated. The in situ formed C/Se composites exhibit superior cycling stability for both Li-ion and Na-ion batteries in carbonate-based electrolytes. The reversible capacity of the in situ formed C/Se composites is maintained at 430 mA h g 1 after 250 cycles in Li-ion batteries and 280 mA h g 1 after 50 cycles in Na-ion batteries at a current density of 100 mA g .