Fabrication of High-Aspect-Ratio Electrode Arrays for Three-Dimensional Microbatteries

• Published in: Journal of microelectromechanical systems 2007-08, Vol.16 (4), p.844-852
• Main Authors: Chamran, F., Yuting Yeh, Hong-Seok Min, Dunn, B., Chang-Jin Kim
• Format: Article
• Language: English
• Subjects: Applied sciences; Area measurement; Arrays; Batteries; Battery charge measurement; Density measurement; Electrodes; Electronics; Energy measurement; energy storage; Etching; Exact sciences and technology; Fabrication; Geometry; Instruments, apparatus, components and techniques common to several branches of physics and astronomy; Mechanical engineering. Machine design; Mechanical instruments, equipment and techniques; micro electrodes; microbattery; Microelectrodes; microelectromechanical devices; Microelectronic fabrication (materials and surfaces technology); Micromechanical devices and systems; Micrometers; Microorganisms; Molds; Nanostructure; Physics; Precision engineering, watch making; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Silicon; Three dimensional; three-dimensional (3-D) battery; Zinc
• ISSN: 1057-7157; 1941-0158
• DOI: 10.1109/JMEMS.2007.901638

Silicon-micromachining techniques have been combined with conventional material-synthesis methods to develop microelectrodes for 3-D microbatteries. The resulting electrodes feature an organized array of high-aspect-ratio microscale posts fabricated on the current collector to increase their surface area and volume for a given footprint area of the device. The diameter of the posts ranges from a few micrometers to a few hundred micrometers, with aspect ratios as high as 50. The fabrication approach is based on micromolding of the electrode materials and subsequent etching of the mold to release the electrode structures. Deep reactive-ion-etching or photo-assisted anodic etching has been used to form an array of deep holes in the silicon mold. Electroplating or colloidal-processing method has been used to fill the mold with battery-electrode materials. Measurements on electrochemical half-cells indicated that the 3-D electrode arrays, which are composed of vanadium oxide nanorolls or carbon, exhibited much greater energy densities (per-footprint area) than that of the traditional 2-D electrode geometries. The use of electroplating enabled us to fabricate 3-D interdigitated arrays of nickel and zinc; and battery operation was demonstrated. [2006-0293].