TY - JOUR
T1 - Ultrahigh dielectric constant and low loss of highly-aligned graphene aerogel/poly(vinyl alcohol) composites with insulating barriers
AU - Wang, Zhenyu
AU - Han, Ne Myo
AU - Wu, Ying
AU - Liu, Xu
AU - Shen, Xi
AU - Zheng, Qingbin
AU - Kim, Jang Kyo
N1 - Funding Information:
The project was supported by the Research Grants Council (GRF Projects: 16203415, 16229216, 16205517, and 16209917) of Hong Kong SAR. Postgraduate Scholarships from the Centre for 1D/2D Quantum Materials, HKUST are also appreciated. Z.W. and X. S. were the recipient of the Hong Kong Ph.D. Fellowship. Technical assistance from the Materials Characterization and Preparation Facilities (MCPF), Advanced Engineering Materials Facilities (AEMF), the Department of Chemical and Biomolecular Engineering and Department of Electronic and Computer Engineering (Prof. Philip K.T. Mok) of HKUST is appreciated.
Publisher Copyright:
© 2017 Elsevier Ltd
PY - 2017/10
Y1 - 2017/10
N2 - A novel two-step route to prepare graphene aerogel (GA)/poly(vinyl alcohol) (PVA) composites with exceptional dielectric performance is reported. The composites obtained from the initial unidirectional freeze casting possess a highly-aligned, conducting graphene skeleton with an ultralow density, a high porosity and remarkable thermal stability, showing ultrahigh dielectric constants combined with moderate losses. The losses are significantly reduced by means of PVA barriers introduced between the neighboring conductive main skeletons of the aligned GA/PVA networks in the 2nd freeze casting process. The insulating barriers effectively block the current leakage by removing the transversely interconnected, conductive ligaments. The compaction of barrier-shielded, porous GA/PVA composites yield fully consolidated, solid composites which deliver both exceptional dielectric constants and very stable, low losses. The approach developed here paves the way for rational design and assembly of GA/PVA composites as a lightweight, tunable and high-performance dielectric material, satisfying various requirements for emerging applications.
AB - A novel two-step route to prepare graphene aerogel (GA)/poly(vinyl alcohol) (PVA) composites with exceptional dielectric performance is reported. The composites obtained from the initial unidirectional freeze casting possess a highly-aligned, conducting graphene skeleton with an ultralow density, a high porosity and remarkable thermal stability, showing ultrahigh dielectric constants combined with moderate losses. The losses are significantly reduced by means of PVA barriers introduced between the neighboring conductive main skeletons of the aligned GA/PVA networks in the 2nd freeze casting process. The insulating barriers effectively block the current leakage by removing the transversely interconnected, conductive ligaments. The compaction of barrier-shielded, porous GA/PVA composites yield fully consolidated, solid composites which deliver both exceptional dielectric constants and very stable, low losses. The approach developed here paves the way for rational design and assembly of GA/PVA composites as a lightweight, tunable and high-performance dielectric material, satisfying various requirements for emerging applications.
UR - http://www.scopus.com/inward/record.url?scp=85026377520&partnerID=8YFLogxK
U2 - 10.1016/j.carbon.2017.07.079
DO - 10.1016/j.carbon.2017.07.079
M3 - Journal article
AN - SCOPUS:85026377520
SN - 0008-6223
VL - 123
SP - 385
EP - 394
JO - Carbon
JF - Carbon
ER -