Free‐Standing 3D Nanoporous Duct‐Like and Hierarchical Nanoporous Graphene Films for Micron‐Level Flexible Solid‐State Asymmetric Supercapacitors. Issue 18 (4th July 2016) - Qin, Kaiqiang
Abstract : High energy density and power density within a limited volume of flexible solid‐state supercapacitors are highly desirable for practical applications. Here, free‐standing high‐quality 3D nanoporous duct‐like graphene (3D‐DG) films are fabricated with high flexibility and robustness as the backbones to deposit flower‐like MnO2 nanosheets (3D‐DG@MnO2 ). The 3D‐DG is the ideal support for the deposition of large amount of active materials because of its large surface area, appropriate pore structure, and negligible volume compared with other kinds of carbon backbones. Moreover, the 3D‐DG preserve the distinctive 2D coherent electronic properties of graphene, in which charge carriers move rapidly with a small resistance through the high‐quality and continuous chemical vapor deposition‐grown graphene building blocks, which results in a high rate performance. Marvelously, ultrathin (≈50 μm) flexible solid‐state asymmetric supercapacitors (ASCs) using 3D‐DG@MnO2 as the positive electrode and 3D hierarchical nanoporous graphene films as the negative electrode display ultrahigh volumetric energy density (28.2 mW h cm −3 ) and power density (55.7 W cm −3 ) at 2.0 V. Furthermore, as‐prepared ASCs show high cycle stability clearly demonstrating their broad applications as power supplies in wearable electronic devices. Abstract : A lightweight and flexible solid‐state asymmetric supercapacitor with a total thickness of ≈50 μm is assembled using 3D nanoporous duct‐like graphene@MnO2 and 3D hierarchical nanoporous graphene films as the positive and negative electrodes, respectively, delivering a superb volumetric performance.