Interlinked Porous Carbon Nanoflakes Derived from Hydrolyzate Residue during Cellulosic Bioethanol Production for Ultrahigh-Rate Supercapacitors in Nonaqueous Electrolytes

The rapid development of cellulosic bioethanol has produced a mass of hydrolysate residue as byproducts during the pretreatment process of lignocellulose. The high value-added utilization of hydrolysate residue plays a key role in the economic viability of large-scale/green industrial production of lignocellulose into bioethanol. Here the hydrolyzate residue was exploited as a carbon precursor for the fabrication of an interlinked graphitized porous carbon nanoflake (GPCNF) by an in situ carbonization–activation process. The final GPCNF presents an optimum integration of a large surface area of 2026 m2 g–1, bimodal pore systems (86% of mesopore volume), and an excellent electric conductivity of 5.4 S cm–1. These characteristics favorably endow that the GPCNF is ideally suited for nonaqueous electrolyte-based supercapacitor applications. In organic electrolyte of 1 M TEA BF4/AN, the GPCNF-based supercapacitor exhibits a high rate capability of 74% initial capacitance at a high current density of 100 A g–1. Notably, in an ionic liquid electrolyte of EMI TFSI the GPCNF-based supercapacitor displays an integrated high energy–power property at an energy density of 37.7 Wh kg–1 corresponding to a high power density of 77.5 kW kg–1, which puts the GPCNF on the Ragone plot among the best energy–power characteristics in the reported two-dimensional biomass-derived carbon electrodes for nonaqueous electrolyte-based supercapcitors.