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- Title
Confining TiO<sub>2</sub> Nanotubes in PECVD-Enabled Graphene Capsules Toward Ultrafast K-Ion Storage: In Situ TEM/XRD Study and DFT Analysis.
- Authors
Cai, Jingsheng; Cai, Ran; Sun, Zhongti; Wang, Xiangguo; Wei, Nan; Xu, Feng; Shao, Yuanlong; Gao, Peng; Dou, Shixue; Sun, Jingyu
- Abstract
Highlights: G-TiO2 was fabricated via direct CVD route by growing few-layered graphene capsules over TiO2 nanotubes. K-ion hybrid capacitors based on the G-TiO2 anode and AC cathode synergized high energy and high power density. Titanium dioxide (TiO2) has gained burgeoning attention for potassium-ion storage because of its large theoretical capacity, wide availability, and environmental benignity. Nevertheless, the inherently poor conductivity gives rise to its sluggish reaction kinetics and inferior rate capability. Here, we report the direct graphene growth over TiO2 nanotubes by virtue of chemical vapor deposition. Such conformal graphene coatings effectively enhance the conductive environment and well accommodate the volume change of TiO2 upon potassiation/depotassiation. When paired with an activated carbon cathode, the graphene-armored TiO2 nanotubes allow the potassium-ion hybrid capacitor full cells to harvest an energy/power density of 81.2 Wh kg−1/3746.6 W kg−1. We further employ in situ transmission electron microscopy and operando X-ray diffraction to probe the potassium-ion storage behavior. This work offers a viable and versatile solution to the anode design and in situ probing of potassium storage technologies that is readily promising for practical applications.
- Subjects
NANOTUBES; TITANIUM dioxide; CHEMICAL vapor deposition; ENERGY harvesting; GRAPHENE; ACTIVATED carbon
- Publication
Nano-Micro Letters, 2020, Vol 12, Issue 1, pN.PAG
- ISSN
2311-6706
- Publication type
Article
- DOI
10.1007/s40820-020-00460-y