Sequential entrapping of Li and S in a conductivity cage of N-doped reduced graphene oxide supercapacitor derived from silk cocoon: a hybrid Li–S-silk supercapacitor

Abstract

Li and S compounds are currently exploited for their applications in battery industry. Here, we discovered that Li–S compounds exhibit supercapacitor like properties in a context-dependent manner viz., when Li and S atoms are entrapped in a conductivity cage of N-doped reduced graphene oxide (ND–RGO) supercapacitor derived from silk cocoon, it resulted in the formation of a superior hybrid Li–S-silk (ND–RGO–Li–S) supercapacitor. Interestingly, ND–RGO–Li–S proves to be a better supercapacitor than ND–RGO alone. Electrochemical properties of ND–RGO versus ND–RGO–Li–S indicated that the later has higher capacitance (~ 10.72%), lower resistance (~ 2.98%), and higher time constant or relaxation time (~ 7.52%). Thus, in one of the first attempts, caging Li and S in ND–RGO supercapacitor matrix offers a new role for Li–S, as an improved supercapacitor, unlike its current application as a battery.