Dielectric capacitors, made from metal electrodes separated by a solid dielectric film, have been widely considered as a stable energy storage system with high power. However, the storage capability lags because only limited surface charges are usable. Therefore, enhancing the energy density of dielectric capacitors has become a valuable goal. The effective route for enhancement of the energy density is to increase the specific surface area of the electrodes. However, with the increase of the specific surface area, the operating voltage could degrade, decreasing the associated energy density. 

Meng Guowen’s research group from the Institute of Solid State Physics (ISSP), Chinese Academy of Science (CAS), with cooperation from Li Song from the University of Science and Technology of China and Wei Bingqing from the University of Delaware, has successfully applied a nanoscale electrode design to enhance energy storage of dielectric capacitors.

Researchers designed a newly structured dielectric capacitor with three-dimensional (3D) nanoscale interdigital electrodes (Figure 1A). As a dielectric layer, a unique nanoporous anodic aluminum oxide (AAO) membrane was fabricated, with two sets of interdigitated and isolated straight nanopores opening towards opposite planar surfaces (Figure 1B). By depositing carbon nanotubes (CNTs) in both sets of pores inside the AAO membrane, a new dielectric capacitor can be produced (Figure 1C).

The high specific surface area and dielectric constant of AAO can provide a high capacitance, while uniform pore walls and hemispheric barrier layers of AAO raise the breakdown voltage. The capacitor can hold two watts per kilogram, a greater energy density than that of any other dielectric capacitor.

Prof. Meng and his coworkers expected the capacitor to find use in many fields, such as accessory power supply and hybrid power systems. This study was published in Science Advances, the first open access, online-only journal of AAAS.

The research was supported by National Key Basic Research Program of China, National Natural Science Foundation of China, Chinese Academy of Sciences/State Administration of Foreign Experts Affairs International Partnership Program for Creative Research Teams, and Anhui Provincial Natural Science Foundation.

Key words: Dielectric capacitor, energy density, anodic aluminum oxide (AAO), Interdigital electrodes 

For more information, please contact: 

http://advances.sciencemag.org/content/1/9/e1500605  

Dielectric Capacitors with Three-Dimensional Nanoscale Interdigital Electrodes for Energy Storage  

Han Fangming, Meng Guowen, Zhou Fei, Song Li, Li Xinhua, Hu Xiaoye, Zhu Xiaoguang, Wu Bing, Wei Bingqing 

Network Media Link:  

http://www.eurekalert.org/pub_releases/2015-10/uod-cb102315.php  

http://phys.org/news/2015-10-nanotechnology-approach-storage-ability-dielectric.html  

http://www.sciencedaily.com/releases/2015/10/151024092537.htm