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Hydrothermally Oxidized Single‐Walled Carbon Nanotube Networks for High Volumetric Electrochemical Energy Storage
Author(s) -
Liu Tianyuan,
Davijani Amir A. Bakhtiary,
Sun Jingying,
Chen Shuo,
Kumar Satish,
Lee Seung Woo
Publication year - 2016
Publication title -
small
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.785
H-Index - 236
eISSN - 1613-6829
pISSN - 1613-6810
DOI - 10.1002/smll.201600974
Subject(s) - materials science , carbon nanotube , gravimetric analysis , electrochemistry , electrode , hydrothermal circulation , chemical engineering , carbon fibers , redox , nanotechnology , surface modification , nanotube , nitric acid , energy storage , x ray photoelectron spectroscopy , composite material , chemistry , organic chemistry , power (physics) , physics , quantum mechanics , composite number , engineering , metallurgy
Improving volumetric energy density is one of the major challenges in nanostructured carbon electrodes for electrochemical energy storage device applications. Herein, a simple hydrothermal oxidation process of single‐walled carbon nanotube (SWNT) networks in dilute nitric acid is reported, enabling simultaneous physical densification and chemical functionalization of the as‐assembled randomly‐packed SWNT films. After the hydrothermal oxidation process, the density of the SWNT films increases from 0.63 to 1.02 g cm −3 and a considerable amount of redox‐active oxygen functional groups are introduced on the surface of the SWNTs. The functionalized SWNT films are used as positive electrodes against Li metal negative electrodes for potential Li‐ion capacitors or Li‐ion battery applications. The functionalized SWNT electrodes deliver high volumetric as well as gravimetric capacities, 154 Ah L −1 and 152 mAh g −1 , respectively, owing to the surface redox reactions between the introduced oxygen functional groups and Li ions. In addition, these electrodes exhibit a remarkable rate‐capability by retaining its high capacity of 94 Ah L −1 (92 mAh g −1 ) at a high discharge rate of 10 A g −1 . These results demonstrate the simple hydrothermal oxidation process as an attractive strategy for improving the volumetric performance of nanostructured carbon electrodes.