Recently, a research team led by Prof. LI Xiaoguang from University of Science and Technology of China (USTC) of the Chinese Academy of Sciences (CAS), in collaboration with Prof. SHEN Yang from Tsinghua University, made important progress in the field of flexible capacitors with high energy storage density. Researchers used negatively charged nanosheets to enhance the energy-storage capability of polymer-based nanocomposites. The results demonstrated a new horizon of high-energy-density ﬂexible capacitors and was published in Advanced Materials.
Dielectric materials with an intrinsic fast charge–discharge capability exhibit the highest power density among all currently available electric energy storage materials. Thus, they are crucial for advanced electronic devices and power grids.
Flexible polymers with relatively higher breakdown strength become a preferred choice for dielectric energy storage. Polymer-based dielectric materials play a key role in advanced electronic devices and electric power systems. Although extensive research has been devoted to improve their energy-storage performances, it is a great challenge to increase the breakdown strength of polymer nanocomposites in terms of achieving high energy density and good reliability under high voltages.
In this work, signiﬁcantly enhanced energy storage capabilities are demonstrated in different ﬂexible polymer-based nanocomposites by the addition of negatively charged Ca2Nb3O10 (CNO) nanosheets. The CNO nanosheets eventually lead to the simultaneously enhanced relative dielectric constant and breakdown strength of poly (vinylidene ﬂuoride) (PVDF)-based nanocomposites.
The signiﬁcantly enhanced breakdown strength of 792 MV m−1 and the record-high recoverable energy density of 36.2 J cm−3 are demonstrated in PVDF-based nanocomposite capacitors with negatively charged CNO nanosheets. Similar substantial enhancements in break-down strength and energy density have also been obtained in PS-based polymer composite capacitors ﬁlled with these nanosheets.
The strategy generalizability is veriﬁed by the similar substantial enhancements of breakdown strength and energy density in polystyrene-based nanocomposites. Phase-ﬁeld simulations demonstrate that the further enhanced breakdown strength is ascribed to the local electric ﬁeld, produced by the negatively charged Ca2Nb3O10 nanosheets sandwiched with the positively charged polyethyleneimine, which suppresses the secondary impact-ionized electrons and blocks the breakdown path in nanocomposites.
All these results will arouse an extensive attention to the excellent energy storage performance of nanocomposites with negatively charged nanoﬁllers, and their work provides a very competitive strategy to further improve energy storage performance of ﬂexible polymer-based capacitor devices.
Phase-ﬁeld simulations for the breakdown phase evolution (Image by LI Xiaoguang et al.)
(Written by LI Xiaoxi, edited by LU Hongyu, USTC News Center)
On May 11, the Nature Publishing Group released Nature Publishing Index 2010 China, remarking “a dramatic rise in the quality of research being published by China”. University of Science and Technology of China is ranked 3rd of TOP 10 Institutions in Index 2010 China.
This article came from News Center of USTC.