Hierarchical Porous Nitrogen-Doped Carbon Nanosheets Derived from Silk for Ultrahigh-Capacity Battery Anodes and Supercapacitors

TLDR

The material is promising for next‑generation hybrid energy storage and renewable delivery devices. Hierarchical porous nitrogen‑doped carbon nanosheets were fabricated from silk by simultaneous activation and graphitization, then assembled into lithium‑ion battery anodes and two‑electrode supercapacitors exploiting their synergistic porosity, surface area, and nitrogen doping. The HPNC‑NS deliver an unprecedented lithium‑ion capacity of 1865 mAh g⁻¹ and a supercapacitor capacitance of 242 F g⁻¹ with 102 Wh kg⁻¹ energy density, retaining 91 % capacity after 10 000 cycles.

Abstract

Hierarchical porous nitrogen-doped carbon (HPNC) nanosheets (NS) have been prepared via simultaneous activation and graphitization of biomass-derived natural silk. The as-obtained HPNC-NS show favorable features for electrochemical energy storage such as high specific surface area (SBET: 2494 m(2)/g), high volume of hierarchical pores (2.28 cm(3)/g), nanosheet structures, rich N-doping (4.7%), and defects. With respect to the multiple synergistic effects of these features, a lithium-ion battery anode and a two-electrode-based supercapacitor have been prepared. A reversible lithium storage capacity of 1865 mA h/g has been reported, which is the highest for N-doped carbon anode materials to the best of our knowledge. The HPNC-NS supercapacitor's electrode in ionic liquid electrolytes exhibit a capacitance of 242 F/g and energy density of 102 W h/kg (48 W h/L), with high cycling life stability (9% loss after 10,000 cycles). Thus, a high-performance Li-ion battery and supercapacitors were successfully assembled for the same electrode material, which was obtained through a one-step and facile large-scale synthesis route. It is promising for next-generation hybrid energy storage and renewable delivery devices.