In-situ growth of homogeneous δ-MnO2 within lignin based porous carbon to reassemble uniform mesoporous crosslinked 3D-network structure for supercapacitors

Abstract

In order to enhance the electrochemical performances of lignin based porous carbon (LPC), a feasible strategy is to incorporate homogeneous δ-MnO2 nanosheets within the LPC substrate via in-situ redox deposition. This work clarified the effects of different LPC supports and KMnO4 solution concentration on in-situ growth of MnO2 and the electrochemical performances of MnO2/LPC composite. The surface topography of δ-MnO2 significantly depends upon the pores feature of LPC. In-situ growth of δ-MnO2 embedded within LPC nanostructure also has a similar type of N2 adsorption-desorption isotherms of nanopores with the original LPC, belong to the type-IV isotherm with a hysteresis loop of H4 type. Moreover, as the KMnO4 solution concentration increases from 1 to 6 mM, the crystal form of δ-MnO2 within LPC maintains, while the electrochemical performances of MnO2/LPC can be improved. Such a uniform 3D-interlinked mesoporous nanostructure of Mn-4/LPC-CO composite electrode exhibits the highest specific capacitance of 198 F g−1 at 1 A g−1, much higher 190% than that of LPC (104 F g−1). Furthermore, the assembled symmetrical supercapacitor by using as-prepared Mn-4/LPC-CO composite exhibits a high energy density of 3.82 Wh kg−1 at the power density of 125 W kg−1 in voltage range of 0–1 V. This study offers a facile and low-cost approach for fabrication of biomass-based functional nanomaterials that can be used in energy storage devices.