Fabrication of High-Aspect-Ratio Electrode Arrays for Three-Dimensional Microbatteries
ABSTRACT 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].
Article: Nanostructured nickel electrodes using the Tobacco mosaic virus for microbattery applications[show abstract] [hide abstract]
ABSTRACT: The development of nanostructured nickel–zinc microbatteries utilizing the Tobacco mosaic virus (TMV) is presented in this paper. The TMV is a high aspect ratio cylindrical plant virus which has been used to increase the active electrode area in MEMS-fabricated batteries. Genetically modifying the virus to display multiple metal binding sites allows for electroless nickel deposition and self-assembly of these nanostructures onto gold surfaces. This work focuses on integrating the TMV deposition and coating process into standard MEMS fabrication techniques as well as characterizing nickel–zinc microbatteries based on this technology. Using a microfluidic packaging scheme, devices with and without TMV structures have been characterized. The TMV modified devices demonstrated charge–discharge operation up to 30 cycles reaching a capacity of 4.45 µAh cm −2 and exhibited a six-fold increase in capacity during the initial cycle compared to planar electrode geometries. The effect of the electrode gap has been investigated, and a two-fold increase in capacity is observed for an approximately equivalent decrease in electrode spacing.J. Micromech. Microeng. 01/2008; 18.
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ABSTRACT: A novel super ink jet printing (SIJP) system was used to fabricate 3D zinc–silver microbatteries directly on a substrate. The SIJP provides a simple and flexible method to deposit interesting 2D and 3D structures of varying morphologies without the waste and large energy inputs typical of standard microfabrication technologies. The system was used to print pairs of silver electrodes with arrays of pillars on glass substrates, and in the presence of an electrolyte, the battery self-assembled during the first charge. Using an aqueous electrolyte solution of KOH with dissolved ZnO, the SIJP printed structures showed similar electrochemical behavior to batteries composed of silver foil electrodes. For a sparse array of pillars (~2.5% footprint area of each electrode pad occupied by pillars), a capacity increase of 60% was achieved in comparison with a cell with planar electrodes.Journal of Micromechanics and Microengineering 08/2009; 19(9):094013. · 2.11 Impact Factor