Flexible Solid-State Supercapacitors with High Areal Performance Enabled by Chlorine-Doped Graphene Films with Commercial-Level Mass Loading

Abstract

Flexible supercapacitors (FSCs) are promising energy suppliers for the emerging wearable devices. Because of the limited human body surface area, it is vital to prepare a flexible electrode with high areal performance. To address this challenge, we propose a facile hydrochloric acid (HCl) solvothermal strategy to fabricate high areal performance chlorine-doped reduced graphene oxide films (Cl-RGOFs). Owing to the electron-withdrawing effect induced by the doped Cl atoms and reducibility of HCl, the electrical conductivity of Cl-RGOF enhanced 2.5 times compared with the pristine-reduced graphene oxide film, which effectively decreased internal resistance, ensuring impressive capacitive performance. As a result, Cl-RGOF exhibits near-linear growth of specific areal capacitance with the increasing of mass loading to the commercial level. For flexible solid-state supercapacitors (FSSCs), Cl-RGOFs with 11 mg cm–2 mass loading present high areal capacitance of 2312 mF cm–2 and 78.7% capacitance retention from 1 to 20 mA cm–2. The FSSC shows a high areal energy density of 160.6 μW h cm–2 at the power density of 0.5 mW cm–2. Besides, the FSSC also shows stable capacitance at different bending angles or after 500-times bending, demonstrating high flexibility and practicality. This strategy provides a new path for the preparation of high areal performance FSC for wearable devices.

Heteroatom‐Doped and Oxygen‐Functionalized Nanocarbons for High‐Performance Supercapacitors

“…HCl assisted solvothermal method is an effective method to prepare the Cl-rGO samples. [202] Hierarchically porous CDC with Cl and N functionalities deliver the highest gravimetric capacitance of 277.7 F g −1 at 0.5 A g −1 in 6 m KOH (3E) which is higher than that of any reported CDC. [199] Hence the enhanced capacitance can be ascribed to the N-functionalities and corresponding changes.…”

Monocrystalline FeMnO3 on Carbon Cloth for Extremely High-Areal-Capacitance Supercapacitors

“…The FeMnO 3 @CC SSC device has areal specific capacitances of 3.60, 2.57, 1.93, 1.74, and 1.6 F cm –2 (corresponding to the volumetric capacitances of 18.0, 12.84, 9.65, 8.69, and 8.0 F cm –3 ) at 10, 20, 30, 40, and 50 mA cm –2 , respectively. Figure b compares the areal and volumetric power densities and energy density of the FeMnO 3 @CC SSC device with the values reported for other high-performance supercapacitors. ,− The maximum areal energy density of the FeMnO 3 @CC SSC is 1.28 mWh cm –2 at a power density of 8.12 mW cm –2 , and it maintains 0.57 mWh cm –2 at a maximum power density of 42.69 mW cm –2 . The maximum volumetric energy density of the FeMnO 3 @CC SSC is 16.0 mWh cm –3 at a power density of 101.5 mW cm –3 , and it maintains 7.1 mWh cm –3 at a maximum power density of 533.6 mW cm –3 .…”

Interface Engineering on Cellulose‐Based Flexible Electrode Enables High Mass Loading Wearable Supercapacitor with Ultrahigh Capacitance and Energy Density

“…Significantly, the electrode exhibits ultrahigh areal capacitance of 9501 mF cm −2 , which belongs to the highest areal capacitance of carbonaceous electrodes reported to date (Figure 3h). [21,[33][34][35][36][37][38][39][40][41][42][43] Even at an ultrahigh current density of 30 mA cm −2 , a high areal capacitance of 3975 mF cm −2 can still be retained (Figure S17c, Supporting Information). The corresponding gravimetric capacitance based on the total mass of the CNT and nanoparticles is calculated to be 315.6 F g −1 even at high areal mass loading (30.1 mg cm −2 ).…”