In Situ S‐Doped Graphene Film using NaHSO3 as Sulfur Source for High‐Performance Flexible Supercapacitors

Abstract

Herein, sulfur‐doped graphite film (SGF) is developed by a facile method. Graphene oxide (GO) film and low‐cost NaHSO3 are used for carbon and sulfur sources, respectively. A single‐step sulfur doping reaction is used to obtain SGF at 180 °C. The scanning electron microscopy (SEM) analysis of SGF reveals highly loose, highly crumpled characteristics. The SEM–energy‐dispersive spectroscopy shows that S is evenly distributed on the surface of SGF and doping amount of S is 4.6 wt%. SGF can attain high gravimetric and areal specific capacitance of 232.8 F g−1 and 672.5 mF cm−2 at 0.5 A g−1 and 1 mA cm−2 current density, respectively. The SGF shows excellent cycle stability (94.1% capacity retention after 10 000 cycles at 2.0 mA cm−2). Then, the assembled flexible SGF//SGF all‐solid‐state symmetric supercapacitor device can deliver a high energy density of 12.17 Wh kg−1 at a power density of 499.85 kW kg−1. The in situ doping method provides a simplistic and low‐cost synthesis process, which is suitable for large‐scale production of SGF. Furthermore, the well‐developed approach is applied to prepare arbitrary S‐doped matrix of carbon. Simultaneously, the fabricated SGF as the electrode material of flexible supercapacitor devices has great advantages in wearable electronics.