Effect of in-situ derived sulfur dispersion on dual carbon lithium-ion capacitors

Abstract

Lithium-ion capacitors (LICs) bridge the performance gap between the energy-dense lithium-ion batteries and power-dense ultracapacitors. This work elucidates the study of a lithium-ion capacitor with two types of carbonaceous compounds as electrode materials from a single keratin biowaste source. The cysteinic disulfide linkages in keratin results in the derivation of the battery-type sulfur-disperse carbon electrode which shows a blend of Li-ion storage mechanisms resulting from the lithium-sulfur redox activity and lithium-insertion into the carbon host. Whereas, the adsorption characteristics of the heteroporous capacitive carbon make it an ideal candidate for the capacitor-type electrode. The lithium-ion capacitor full cell using prelithiation of sulfur-disperse carbon as the battery-type and heteroporous carbon as the capacitor-type electrode demonstrates energies of 178 and 52 Wh kg−1 at power of 366 and 22,500 W kg−1, respectively in 1:2 anode:cathode mass configuration. In contrast, the 1:1 mass configuration delivers energies of 118 and 72 Wh kg−1 at power of 275 and 13,750 W kg−1 respectively and cycles at 1 A g−1 current density with ∼70% capacitance retention till 5000 cycles. This study further emphasizes the effects of the redox reaction of the in situ sulfur nanoparticles in the performance and the mechanistic control of the LIC.